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FEKO User's Manual - SSH Fingerprints of login.ee.ethz.ch

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1. Note Points are connected in the order that they are listed he last specified pointis connected back to point A Concave corners are allowed Check this item to enable the table in which edge lengths for each edge can be entered Check this item to enable the table in which internal points can be specified Enter the points previously defined with the DP card into the rows of this table Any points internal to the structure where mesh points are re quired can be entered here This is particularly useful for the connection points between surfaces and wires The mesh length on each edge can be set separately in this table Any blank entries in this table will be meshed with the parameters set in the IP card There may not be more entries in this table than in the first one EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 75 The polygon is defined by entering the points previously defined with the DP card on the corners of the polygon A maximum of 13 corner points are allowed The points are connected in the order that they are entered in the PM card Concave corners are allowed The user can also specify a smaller or larger mesh size along certain edges Examples of PM card usage Shown below in figure 9 33 is plate with a concave corner created with the PM card note the finer mesh along the edges from B to C and C to D A pl
2. Figure 9 21 First example for the KR card from demo_KR1 pre EM Software amp Systems S A Pty Ltd December 2005 9 62 DESCRIPTION OF THE GEOMETRY CARDS 9 2 24 KU card This card creates a mesh of surface triangles in the shape of a spherical section Parameters S1 S2 93 Normal direction Begin angle Va Begin angle pa Begin angle Ue Begin angle pe KU Specify a spherical section Normal direction e Inward Outward Begin angle a degrees rn Begin angle Y a degrees po o End angle e degrees po 1 End angle Y e degrees po is Maximum triangle edge length po The centre of the sphere A point that indicates the Y 0 direction in a spherical coordi nate system The distance between 1 and 82 is the radius of the sphere A point that indicates the Y 90 y 0 direction in a spherical coordinate system The distance S1 53 must be equal to the distance 1 S2 The triangles can be created such that the normal vectors point Outward away from the centre of the sphere or Inward towards it The start angle Y in degrees of the spherical segment The start angle pa in degrees of the spherical segment The end angle Ve in degrees of the spherical segment The end angle ye in degrees of the spherical segment Mazimum triangle edge length The maximum length of the triangles along the curved edges in m is scaled by the SF card
3. This is an assembly Indicators si This item has been transformed This part contains dielectric regions Metal face on a dielectric This item is suspect it could not be mapped Local mesh properties on regions faces edges al Ai Non metal face on a dielectric gt g Q Local wire radius EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 13 Transforms w Translation Rotation WZ Scale dk Mirror Right clicking in the tree will open an appropriate pop up menu Double clicking on an item in the tree will display the Properties for that item except for the Variables and Named points headings in which case a new item is added The tree area can be hidden by dragging the slider all the way to the left and shown again by dragging the slider to the right again or by selecting View Tree from the CADFEKO menu 4 5 Variables and named points CADFEKO supports parametric models Thus most input values can be specified using variables or mathematical expressions such as 1 sqrt x where x is a user defined vari able The expressions are then stored with the model and when a variable is changed all items depending on it are updated It is therefore very easy to adapt a model using variables and a little planning for example to modify the geometry for use at a different frequency Since it is possi
4. 4 7 8 Reversing face normals Face normals can be reversed by selecting the faces and selecting Reverse face normals from the pop up menu in the details tree or Geometry Reverse face normals from the main menu The normals of all selected faces are reversed even though only one part s faces are shown in the details tree at any given time Currently it is not possible to reverse the normal on a body with a single closed face for example a sphere If such a normal must be reversed the simplest option is to project a circular line onto the body such that it creates two faces The normals of these faces can then be reversed and the edge deleted by simplifying see below the part afterwards 4 7 9 Removing detail and the simplify operation Redundant faces may be deleted by selecting them and pressing the lt Del gt key or selecting Delete from the pop up menu Faces can only be redundant if they have the same medium i e metal free space or the same dielectric medium see section 4 8 on both sides When a face separating an internal free space region from the outside free space is deleted the internal region is merged with the outside Since the outside medium is free space surfaces can only be removed from closed regions if the internal medium is set to Free space Redundant and free edges may be deleted similarly These items are permanently re moved but it is possible to copy the original object see section 4 7 11 Als
5. December 2005 FEKO User s Manual 5 6 THE EDITOR EDITFEKO 5 3 1 Appearance tab Here the user can e Switch off the top toolbar e Set the printer font e Set the size of the screen fonts e Set the preferred card format In the column based card format the fields are located at fixed positions and cannot be longer than 5 string and integer fields or 10 real fields characters In the colon separated format the different fields in each card are separated with characters This format allows arbitrary long entries If EDITFEKO is using column based format it will automatically switch to colon separated format if any of the input fields are longer than the allowed length 5 3 2 Options tab Here one may e Elect to show superuser options if this is allowed by the license The superuser mode in FEKO is only used during program development and is not available to the general user If one tries to edit an existing card containing superuser parame ters EDITFEKO will also prompt the user and switch to superuser mode if this is allowed If the license does not allow superuser mode superuser options will be removed e Turn on auto save and or backups and specify the auto save interval e Specify the PDF reader required for the manuals 5 4 PREFEKO mode 5 4 1 Generating input cards Cards can be entered and edited directly in the editor window In most cases the user would call one of the card editor dialogs by clicking on
6. OOOO Parameters First drop down list Here we select what to calculate e No field calculation Field is not calculated Electric field values Calculate the electric field Magnetic field values Calculate the magnetic field H Both electric field and magnetic field values Calculate both electric and magnetic fields Electric field and SAR values in cuboids The electric field and SAR values in the dielectric volume elements For this option no other parameters are not required Magnetic vector potential Calculate the magnetic vector potential A Gradient of the scalar electric potential Calculate the gra dient of the scalar electric potential V y Electric vector potential Calculate the electric vector po tential F Gradient of the scalar magnetic potential Calculate the gra dient of the scalar magnetic potential V y Calculate only the scattered part of the field When this item is checked only the scattered part of the field potential is written to the output file Oth erwise the total field potential the sum of the scattered and December 2005 FEKO User s Manual 10 72 DESCRIPTION OF THE CONTROL CARDS source contributions are written to the output file Note that de pending on the used formulation in FEKO the region where the incident field as computed from the impressed sources is present might be different for instance when using the surface equiva len
7. It should be noted that when using the remote launching facility see section 8 2 3 the actual TIMEFEKO process is executed on the local machine only the FEKO kernel runs which are the time and memory consuming part are done on the remote machine 12 5 TIMEFEKO output TIMEFEKO generates different pre files at the different frequencies The out files for all these runs are available if TIMEFEKO was called without the r option These results are summarised if they are requested in the pre file in ost triangle currents oss segment currents cur the currents on voltage sources far far fields nfe near electric fields and nfh near magnetic fields In each case the results for each frequency is listed one after the other with frequencies separated by a line containing a single character The time domain results are given in the aus file for all outputs requested in the pre file Currents are requested by the OS card Note that requesting the current on a large number of structures will result in very large aus files EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO 12 9 12 6 A TIMEFEKO example In figure 12 7 an ideal conducting metallic cube with side lengths of 1m is shown The current in the middle of the front side the scattered field from the direction of incidence the incident wave travels in the negative x direction as well as the excitation pulse ar
8. Note that when using the FEM in the same model metallic structures are allowed metal lic surfaces also inside the FEM region or on the FEM boundary wires only outside But using dielectric bodies inside the MoM region at the same time is not supported Example of QT card usage The dielectric cuboid shown in figure 9 36 is generated using a QT card Figure 9 36 Example for the QT card from demo_QT1 pre December 2005 FEKO User s Manual 9 82 DESCRIPTION OF THE GEOMETRY CARDS 9 2 34 QU card This card is used to create a dielectric or magnetic cuboid meshed into smaller cuboidal volume elements for solutions using the volume equivalence principle in the MoM The meshing parameters as set at the IP card are used and the medium as set at the ME card is assigned to all created cuboidal elements Parameters SE S2 93 S4 Choose the medium Dielectric Magnetic C Both dielectric and magnetic QU Specify a dielectricimagnetic cuboid 2 sf a 1 sa St A 34 Choose the medium J Old format with medium parameters First corner of the cuboid Opposite corner of the cuboid if aligned with the principle planes otherwise one of the corners adjacent to the first corner Optional third corner of the cuboid adjacent to the first Optional fourth corner of the cuboid adjacent to the first Select here whether the cuboid is dielectric or magnetic or both this is alw
9. e connected to ground UTD Excite the edges of metallic tri angles with the label specified in the Label of triangles con nected to ground which are connected to UTD surfaces or to a PEC ground plane as specified with a BO or GF card The positive feed direction is towards the UTD region or ground plane e of microstrip between two points This is a special microstrip line feed The excitation is placed on all edges on a line between points previously specified with DP cards The points are specified in the Start point of edge and End point of edge dialogs A GF card with a conducting ground must be present The positive source direction is from the trian gles towards the edge EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 27 Label I2 Label 13 E 1 Figure 10 4 Example of the use of the AE card Magnitude of source Magnitude value of the voltage Uo in V Phase of source Phase of the voltage Uo in degrees S parameter impedance The reference impedance to use for this excitation if it is included in an S parameter calculation requested by the SP card If this field is empty or 0 the impedance specified at the SP card is used This value is only used if an SP card is applied to this source The positive source direction as used above is in the direction of the current flow through the edge The internal EMF electromagnetic force of the imp
10. 1 2 3 component of the electric field strength in the ith block with i 1 Ng and the jth line in this block with j 1 Ng then we define normalised field strength values as where Enorm is the Neompth component of the Nnormth field strength value that has been selected for the normalisation this is a complex quantity with amplitude and phase When normalisation has been switched off then in the above equation we normalise with Ey orn 1 i e basically e is then equal to Ex but without dimension For the magnetic near field with normalisation switched off we use Hnorm 14 December 2005 FEKO User s Manual 11 26 THE OPTIMISER OPTFEKO The aim function f for the optimisation is then defined as Ns 1 f Y Arlene eth fa lezas eSNG fa lesas esil j 1 The values en are the desired field values and they must be specified in the table on the panel T here are in total Ng Ns lines with all the field values and each line has 6 columns with magnitude and phase in degree of the 3 normalised field strength components 1 4 2 5 and ez the inner loop is the one over j i e the values appear in the same order as they would be in the output file le1ij phase e1i lez phase e2i lez phase ez In the line Naorm of this table the component Necomp which we are normalising to must be 1 in amplitude and 0 in phase So far only the case for the electric field has been disc
11. 9 2 28 PB card This card can be used to generate a section of a parabolic reflector as shown in the figure on the card PB Specify a parabaloid section S4 Se si sa f s sa Subtended angle Y degrees Po Maximum triangle edge length iY Parameters S1 The centre of the paraboloid 52 A point perpendicular to the base plane and at any distance above the centre point 53 A point on the outer edge of the paraboloid but on the base plane S4 A point in the plane 2 S1 S3 directly above S3 on the edge of the paraboloid Subtended angle p The angle subtended by the arc of the parabolic reflector in de grees Maximum triangle edge length Maximal edge length of the triangles along the outer edge of the arc in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used The radius R of the paraboloid is derived from the distance between the points S1 and S3 as can be seen in the figure in the card The height is determined by the distance between points 3 and 4 The focal point f is determined by R2 faz EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 71 Example of PB card usage The parabolic reflector as shown in figure 9 29 can be generated by using the PB card Figure 9 29 Example for the PB card from demo_PB1 pre December 2005 FEKO User s Manual 9 72 DESCRIPTION OF THE GEOMETR
12. FR Set the frequency and terminate AC loop AO Specify plane wave excitation F o Calculate the near field 0S us Output the currents End EN December 2005 FEKO User s Manual 10 26 DESCRIPTION OF THE CONTROL CARDS 10 2 12 AE card This card specifies an excitation at an edge between triangular surface elements similar to the A7 card but the AE card has the advantage that the location of the feed point and the positive feed direction are substantially easier to specify In addition it is possible to specify a feed edge which contains a number of triangle edges as shown in figure 10 4 AE Edge voltage source between labels New source Add to sources Excite edge between regions with two labels C connected to ground UTD of microstrip between two points Label on one side of edge Label on second side of edge mu Magnitude of source V Po _ Phase of source degrees S parameter impedance Ohm Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Excite edge This specifies how the edge is determined e between regions with two labels The excitation is placed on the edge between the regions with labels specified in Label on one side of edge and Label on second side of edge The positive source direction is towards the second side
13. Radar cross section RCS With this aim function the RCS o can be minimised or maximised either the average value or the minimum maximum value over a range of angles and over a range of frequencies blocks December 2005 FEKO User s Manual 11 18 THE OPTIMISER OPTFEKO Aim function ap Aim 1 Select aim function Radar cross section y Weighting factor fi ROS Maximise min Minimise ave Maximise ave Minimise max Treatment for multiple blocks Averaging over the blocks C Take maximum minimax principle Number of blocks Number of values per block IV Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions RCS The type of RCS optimisation that should be performed must be selected in this box See the description of the different aim functions below Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read For each block i 1 Np the first row is read and the gain directivity g in dB is extracted Number of values per block This must be set to the number of rows that are to be read from each block i e the number of discrete points 4 pj when varying the angle
14. Rotation around the z axis Angle of rotation az around the z axis in degrees Translation along the x axis Translation A in the direction in m scaled by SF card Translation along the x axis Translation A in the y direction in m scaled by SF card Translation along the x axis Translation A in the z direction in m scaled by SF card Scale factor The scaling factor y with which the structures must be scaled If left empty it defaults to 1 For wire segments the wire radius is scaled as well as the coordinates of the start and end points When an SY card symmetry is used before the TG card the TG card resets the sym metry if the new structures invalidates the symmetry Cases where the symmetry is not reset is when for example the plane z 0 is a symmetry plane and the TG card spec ifies rotation about the z axis for a symmetrical selection of elements In this case the symmetry is retained If more than one copy is made successive points are generated from the previous point using the same relation With a TG card the simultaneous rotation around multiple axes as well as translation in multiple directions is possible A point x y z for example the corner point of a triangle is transformed to a new point Lp x Az yr yM y 17 Ay Zr z A with the rotation matrix COS Qy COS Qz COS Qy Sin Az sin Qy M cosaz sinaz sin Qg sin Qy COS Az COS Mz COS Az SIN Qg SIN Qy SIN Az S N Qg COS Qy sin
15. T Bap j iro for right hand circular polarisation If the excitation is an incident wave the results include the radar cross section In the case of voltage sources the gain or directivity are included see the parameters of the FF card For the radar cross section the incident plane wave with complex amplitude Es carries a power density of 1 E got Eo 2 Zro Zro denotes the wave impedance of the surrounding medium which gets scattered on the object and a wave is reflected with the scattered power density 1 i Etar o Ear wal dal Zro The radar cross section RCS is then defined as R Efar 91 R Ewel Es o lim Am R 28 lim 47 R 0o Si R 00 EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 13 For antenna and general radiation problems as mentioned above FEKO is computing either the gain or the directivity depending on the FF card setting this applies to the values tabulated in the out file only in POSTFEKO any quantity can be selected Let us assume that P is the source power and P are some losses in the structure e g dielectric losses then a power P P P will be radiated The directivity as compared to an isotropic point source is then defined as Ss 2r R Eraro R Etar pl D 4r R a P Z Fo Pr For the gain a similar definition is used just now the source power P and not the radiated power
16. angular range THETA angular range PHI radiated power 2 50 182 50 deg 2 50 362 50 deg 5 60499E 03 Watt 0 00 180 00 deg 0 00 360 00 deg 5 52821E 03 Watt EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 81 If the problem is symmetrical it is not necessary to carry out the integration over the complete sphere If there are three planes of symmetry as for a simple dipole in free space the integration only needs to be done over an eighth of the sphere The power then has to be multiplied by 8 If a ground plane has been specified the calculation of the far fields below the ground plane is not possible Observation points with z lt 0 will thus be ignored While doing a far field computation spherical mode coefficients can be computed The calculation of these coefficients is based on the far field values and they are written to the FEKO output file Doing the integration requires a two dimensional far field computation i e both Number of Y points and Number of y points larger than 1 over the whole sphere i e 0 lt Y lt 180 and 0 lt lt 360 and the angular increments should be chosen according to the desired accuracy and number of modes i e a finer stepping is required for higher modes It is suggested to do some initial convergence study e g with increments 5 and then 1 to see the sensitivity of the results Spherical modes have three indices s
17. s Manual DESCRIPTION OF THE GEOMETRY CARDS 9 1 9 Description of the geometry cards 9 1 Overview of the geometry cards The following table lists all input cards that are used to create the geometry i e the cards that appear before the EG card in the pre file Most of these cards are processed by PREFEKO For example PREFEKO processes the BP card and writes the triangle elements to the fek file as input to FEKO Card Description 4k characters used to indicate a comment BL creates a line BP creates a parallelogram BQ creates a quadrangle BT creates a triangle CB changes already assigned labels CL creates a circular line using segments CN changes the direction of the normal vector DK creates a dielectric or magnetic eighth of a sphere DP defines a node point DZ creates a cylindrical dielectric shell EG defines the end of the geometry EL creates a segment of an ellipsoid FM set parameters related to the MLFMM FO defines a Fock region FP set parameters related to the FEM HE creates a coil from wire segments IN reads an external include file containing mesh information IP sets the parameter that defines the degree of meshing KA defines the border of the PO area KK creates a elliptical conical segment KL sets the wedges in the PO area KR creates a planar elliptical element KU creates a spherical element LA specifies the label for segments triangles polygons etc ME defines the medium NU creates
18. sion for the storage of some of the memory critical arrays for the MLFMM or FEM only Single precision storage is the default behaviour for these methods December 2005 FEKO User s Manual 9 24 DESCRIPTION OF THE GEOMETRY CARDS The following should be noted regarding the export of the FEKO geometry to NASTRAN or STL e The STL export just dumps the data of all triangular patches of the FEKO model to an ASCII formatted STL file Any other geometry wires tetrahedra etc is not exported since the STL format does not make provision for this Also FEKO does not know any more any relation of the triangular patches to solids and even in FEKO one can model just a plate for instance Thus there is no special grouping of elements in the STL file which does not represent a valid STL file in the strict sense However the exported information might still be useful in many cases e For the NASTRAN export the wide column format is used to ensure that all signifi cant digits are exported Unlike the STL export in NASTRAN all the various mesh elements used in FEKO are present However some information is lost for instance for wire elements the thickness wire radius cannot be exported simply because the NASTRAN file format does not make provision for this Also the NASTRAN prop erty is used to represent the FEKO label But since NASTRAN properties are just integer values and the FEKO label can be an arbitrary string a mapping is done so tha
19. 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 y m JX 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 00000000000e 000 1 111 11E 01 z m 1 11111E 01 JY 18216923283e 008 02561817670e 010 28360949904e 008 4 46200189557e 009 91955007365e 009 27286771090e 010 59541937732e 009 z m 5 55556E 02 2 22222E 01 JY 87039561714e 009 10165720719e 008 92248537619e 009 95306492829e 008 6 20307013697e 009 the back scattered electric far field Ez 97321161834e 008 39083930925e 009 JZ 93459474753e 007 95358888266e 006 34406393148e 006 711500429087e 007 71581870796e 007 21262288818e 006 49801053069e 006 JZ 55875015522e 007 96750870513e 006 37781030380e 006 84072619127e 007 89929184543e 007 24837047986e 006 53916294269e 006 December 2005 FEKO User s Manual 12 14 THE PROGRAM TIMEFEKO Normalised Ez 0 2 4 6 8 10 12 14 16 18 20 Time in light metre Figure 12 8 Time response of the excitation Fiz The parameters of the Gaussian pulse are a 3 0 108 s71 to 20 ns 0 3 Etheta in V 2 4 6 8 10 12 14 16 18 20 Time in light metre Figure 12 9 Response of the back scattered far field E of the cube EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM ADAPTFEKO 13 1 13 The program ADAPTF
20. 2 20 EM Software amp Systems S A Pty Ltd December 2005 Gr PI cos Y eme Ez Br 2 ml cos os gime e c i DESCRIPTION OF THE CONTROL CARDS 10 45 and altrd o Na By ZE 55 gt ar cos 0 eime ep e an Br 20 Br AEP cos 0 eme 2 with the associated Legendre function im 2n 1 n ml im PL cos y 5 n F mpi cos Y and the spherical Bessel functions It should be noted that the Legendre polynomial P cos V as used in FEKO follows the definitions of Abramowitz Stegun also used like this in Numerical Recipes or also Harrington The formulas used in other references e g Stratton or Hansen have an extra factor 1 included This is not considered in FEKO and thus the mode coefficients QSmn might differ from those computed according to Hansen there is also of course the other time dependency see earlier discussion Theoretically the index n runs in the range 1 2 00 For any practical application one will have to consider a finite number of modes only i e limit the range n 1 N Some rules of thumb exist for the selection of N For instance when representing the pattern of an antenna by spherical modes one can use the upper limit gt N Bro 217 where P is the wavenumber the wavelength and ro denotes the radius of the smallest sphere enclosing the antenna In critical cases one might also rather use N amp Bro 10 or
21. 3 s Using this formula it is found that the edge length s should be shorter than approximately According to the geometry and the need for accuracy more or less triangles may be needed If the memory constraints allow it a segment length of seo is preferred When modelling a surface by means of a wire grid the radius should be chosen so that the wire area in one direction is approximately the same as the area of the surface to be modelled as a wire grid From the approximation 27r 1 l one finds the wire radius to be r Qn where l defines the segment length The length on dielectric cuboids has to be small in comparison with the wavelength A in the dielectric as well as the skin depth 2 4 wuo Due to the staircase approximation used a mesh size of or finer is recom mended min A 0 10 When meshing the FEM region into tetrahedral volume elements then as a guideline an element size edge length of the tetrahedra of 2 should be used inside the FEM volume but for those elements right on the FEM MoM interface a finer element December 2005 FEKO User s Manual 2 4 GENERAL COMMENTS size of is recommended The reason why inside a coarser mesh can be used is that higher order basis functions are employed there It should be noted that A represents the wavelength inside of the dielectric medium As a trick to reduce the overall memory requirement of FEKO it might be ad
22. 8 134 and 5 110 2 857 0 0 respectively If any of the coordinate group codes are absent such as in a 2D model the related coordinate is set to zero The block is terminated by the group code 0 The wire is segmented according to the maximum segment length specified by the IP card and the segments also have the radius specified by this card December 2005 FEKO User s Manual 9 44 DESCRIPTION OF THE GEOMETRY CARDS Meshed surfaces are imported from blocks denoted with the keyword POLYLINE This block contains the layer name following the group code 8 as before if there is no group code 8 before the first VERTEX the label specified with the last LA card will be used and a number of VERTEX structures There can be an arbitrary number of VERTEX structures but there should be at least four The POLYLINE structure is terminated by the keyword SEQEND 0 POLYLINE 8 LAYER_02 VERTEX VERTEX VERTEX 0 SEQEND There are two types of vertices The first type defines points in space 0 VERTEX 8 LAYER_02 10 7 919192 20 3 393939 30 0 0 next keyword EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 45 where the x y and z components of the point follow the group codes 10 20 and 30 The layer information is ignored The second type of vertex is a linker 0 VERTEX 8 LAYER_02 70 128 71 4 72 2 73 1 74 3 0 next keyword
23. December 2005 FEKO User s Manual 9 84 DESCRIPTION OF THE GEOMETRY CARDS 9 2 35 RM card The RM card provides a sophisticated remeshing and adaptive mesh refinement facil ity Most types of meshes surface mesh with triangular patches wire segment mesh cuboidal volume elements created by any option supported in FEKO e g direct cre ation in PREFEKO with cards but also import from NASTRAN FEMAP PATRAN etc can be used as a basis and one can then apply either a local or a global mesh refinement Unfortunately in FEKO Suite 5 0 there is still a restriction that tetrahedral volume elements as used for the FEM cannot be refined with the RM card A local mesh refinement refers to a point or a line as reference or also to a complex cable harness geometry which is defined directly by importing the corresponding rsd file from CableMod Note that similar to other FEKO cards the RM card applies only to what follows in the pre file after the line where the RM card has been read So for instance if one wants to import a mesh from a NASTRAN file via the IN card and do a mesh refinement during the import then one first has to use the RM card then followed by the IN card Multiple RM cards can be used for instance if there are multiple areas in a model where the mesh shall be refined locally Or also if we use a mesh refinement with respect to one point the mesh size increases linearly with distance and by adding another RM card wit
24. Insert row Delete row FF Enforce min max boundaries E IV Include default comments Parameters The optimisation parameters are defined in tabular form in this field Each optimisation parameter has a name a symbolic vari able used but not numerically defined in the pre file For each parameter a begin value as well as a minimum and max imum value have to be given The name must include the character Insert row This button is used to add a row to the table Delete row This button is used to remove a row from the table Enforce min max boundaries Check this box to enforce sharp boundaries on the parame ter See the discussion below Errors Any errors in the opt file that were noticed when the file was parsed are shown in this dialog December 2005 FEKO User s Manual 11 4 THE OPTIMISER OPTFEKO Include default comments This box should be checked if the default descriptive comments should be added to the file This checkbox appears at the bottom of all OPTFEKO panels Normally the minimum and maximum values of the optimisation parameters as specified in the opt file are only used for the normalisation of the parameter space In order to en sure that the parameters stay within certain limits a penalty function see section 11 2 3 can be added This will result in a smooth aim function for the optimisation In some circumstances however sharp boundaries must be enforced to avoid i
25. Maximum identical distance Two points less than this distance apart are considered iden tical For an exact description see below If this parameter is not specified it is set internally to 107 m In most cases this value is sensible If scaling is done with the SF card this value is also scaled It is recommended to set this value also referred to as EPSENT only if FEKO demands it with a warning or error message Relative permittivity The relative dielectric constant r of the homogeneous medium in which all structures are contained When this field is empty Er is set to 1 Relative permeability The relative permeability ur of the homogeneous surrounding medium When this field is empty pr is set to 1 Conductivity The conductivity o of the homogeneous surrounding medium in When this field is empty is set to 0 Magnetic loss factor Magnetic loss tangent tan of the homogeneous surrounding medium the complex permeability is then given by H potr 1 j tan d Dielectric loss factor Electrical loss tangent tan of the homogeneous surrounding me dium This is an alternative way to specify the conductivity to which it is related by tand WEPED Mass density The medium density p in kg m of the homogeneous surrounding medium p is only required for the SAR computations and post processing of SAR results in POSTFEKO Solution accuracy This parameter can be set to force FEKO to use single preci
26. Modified YA The main functionality is the specialised card editor dialogs see section 5 4 for PREFEKO input cards It also supports OPTFEKO input files see section 5 5 but currently uses a plain text editor for TIMEFEKO input files December 2005 FEKO User s Manual 5 2 THE EDITOR EDITFEKO The program may be started from a command prompt by entering editfeko example pre where the optional parameter here example pre specifies the file to open If the para meter does not contain an extension the extension pre is added Also if such a file does not exist it will be created EDITFEKO can also be opened from inside CADFEKO and POSTFEKO If a file is opened in EDITFEKO a lock file is created of the form filename ext lock in the same directory as the file If you open the file in another instance of EDITFEKO at the same time it will give a warning A lock file already exists for this file Are you sure you want to continue with this operation with options to cancel or continue Generally one should then click Cancel and switch to the other instance of EDITFEKO One should only continue here if the lock file resulted after EDITFEKO was not closed properly such as a power failure or system crash 5 1 Toolbars The toolbars in EDITFEKO are usually docked at the top of the EDITFEKO window but they can be dragged free or docked on any of the four sides They can also be switched off by selecting File Preferenc
27. N amp Bro 3 Y Bro When using the compressed numbering scheme with one index j any upper limit N for n will with the largest values m N and s 2 translate into an upper limit J 2 N N D N 1 2 2N N 2 December 2005 FEKO User s Manual 10 46 DESCRIPTION OF THE CONTROL CARDS for j i e j 1 J then So for instance for an antenna with enclosing radius ro 4 then Bro 1 57 when using the last of the three rules of thumb above one would need roughly N 5 or J 70 modes respectively For ro A these limits become already N x 12 and J 336 and for rg 5A one has to use N 41 and J 3526 modes The origin r 0 of the modes can be set arbitrarily in space by means of the Source position field However no provision has been made to allow a rotation i e in spherical coordinates the distance r of some point is measured with respect to the mode origin but the angles Y and y are always defined with respect to the global coordinate system The reason why a rotation is not supported here for the AS card as opposed to the A5 or A6 elementary dipoles is that the modes inherently contain this radiation in an arbitrary direction For instance the TM mode n 1 m 0 represents a z oriented electric dipole i e vertical while the TM modes n 1 m 1 represent horizontally aligned dipoles An arbitrary pattern orientation can be obtained by a suitable superposition of different modes The modes have been normalis
28. The aim function depends on the choice of the RCS box above For the other options the per block aim function is given by e Maximise the minimum RCS fi max 1 NsO 0 w e Maximise the average RCS Le ae fi Ns i X ow p5 j 1 EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 19 e Minimise the average RCS ee 00 p3 j 1 e Minimise the maximum RCS fi maxj 1 Nso 0 Py This aim function is chosen by using the keyword RCS Impedance reflection factor With this aim function the input reflection factor of an antenna can be minimised The optimisation can be broad band by examining a number of frequencies at the same time One can also optimise the reflection factor of multiple different ports simultaneously Aim function Aim 1 Select aim function Impedance reflection y E Weighting factor fi a for multiple blocks Averaging over the blocks C Take maximum minimax principle Zreal Zimaginary Number of blocks FF Min reflection coefficient Meo IV Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions Z real The real part of the target impedance Z imaginary The
29. This file is only generated on request by a DA card section 10 2 24 out Output file from FEKO in which the results of all the calculations and messages can be found pcr Exported LU preconditioner for the FEM pfg POSTFEKO graph file p s POSTFEKO session file pre Input file for PREFEKO ray For the UTD an optional ray file can be requested This file is not required when visualising rays in POSTFEKO rhs File containing the right hand side vector in the system of linear equa tions rsd File for coupling of FEKO with CableMod or PCBMod It is usually created by CableMod or PCBMod but can also be created by FEKO if requested with the OS card field calculation along lines sha File storing shadowing information for the PO snp Touchstone format S parameter file as created by the DA card The n refers to the number of ports see section 10 2 24 sph Spherical wave expansion SWE as used by the reflector antenna code GRASP from TICRA can be exported in FEKO using the DA card see section 10 2 24 str File in which the coefficients of the basis functions are stored for reuse generated on request from a PS card section 10 2 39 tim Input file for the program TIMEFEKO vis When multiple reflections are used with the PO formulation FEKO determines which basis functions have line of sight visibility Since this calculation may require significant run time this information can be saved t
30. d2 1 d3 1 O Label d1 2 d2 2 d3 2 O Label di nd d2 nd d3 nd O Label s1 1 s2 1 O O Label s1 2 s2 2 0 O Label s1 ns s2 ns 0 O Label EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 37 nnp 1 pi 1 p2 1 p3 1 Label nnp 2 pi 2 p2 2 p3 2 Label nnp np pi np p2 np p3 np Label The meaning of the above is nk Number of nodes nd Number of triangles ns Number of segments np Number of polygonal plates nt Number of tetrahedral volume elements defaults to 0 if not specified x t x coordinates of node in m is scaled by the SF card y i y coordinates of node i in m is scaled by the SF card z t z coordinates of node 7 in m is scaled by the SF card dl j Number index of the first vertex of triangle j d2 j Number index of the second vertex of triangle j d3 j Number index of the third vertex of triangle j sl k Number index of the starting point of segment k s2 k Number index of the end point of segment k nnp m Number of corner points in polygon m pl m Number index of the first corner of polygon m p2 m Number index of the second corner of polygon m p3 m Number index of the third corner of polygon m Number index of the additional corners of polygon m String name Optional string name of the point It must be a string of up to 5 characters similar to the point name of the DP card If a point is named it can b
31. defines a load on the edge between surface triangles LP defines a parallel circuit resistance inductance and capacitance load LS defines a series circuit resistance inductance and capacitance load LZ defines a complex load OF offset i e displacement of the origin when calculating the near fields OS saves the surface currents in a file PS sets general control parameters PW defines the radiating power of a transmitting antenna SA Used to calculate SAR in dielectric media SK takes a finite conductivity into account through the skin effect of ohmic losses also for thin dielectric layers December 2005 FEKO User s Manual 10 2 DESCRIPTION OF THE CONTROL CARDS SP calculates the S parameters for the active sources TL specifies a non radiating transmission line As mentioned above the control cards form the second part of the input file see also section 2 1 Control cards are processed line by line and only affect other cards and calculations specified below them in the input file Information specified in a control card is not available before that line is processed Any number of control cards can be used but they should adhere to a basic sequence Thus for example the frequency FR card and the type of excitation Ax card must be defined before the near fields can be calculated with an FE card In addition a sensible order for the control cards can result in a considerable reduction in the computat
32. erate elements elements where two or more nodes coincide EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 43 k Remove duplicate mesh elements EJ E3 Keep elements in this order la Union Face1_1 2 Union Face1_2 3 Uriont Facet_3 la Union1 Face1_4 s Union1 Face1_5 e Union1 Face1_6 To order the entries press lt Ctrl gt and drag the entries in the vertical header H OK B Cancel Figure 4 22 The remove duplicate dialog which determines which of the duplicate elements to retain 4 13 7 Finding distorted and oversized elements Since the accuracy of the FEKO results depends on the quality of the mesh CADFEKO allows some mesh validation Selecting Find Distorted mesh elements or Find Over sized mesh elements from the main menu checks the current selection mesh parts labels or elements for distorted or oversized elements respectively The result is a selection of the inappropriate elements The selection Undo and Redo operations can be used to see which elements were selected before and after the test Distorted mesh elements are specified in terms of the minimum internal angle All angles in CADFEKO except the arguments of trigonometric functions used in expressions are in degrees and this is no exception In an ideal mesh all internal angles are 60 degrees and if any of the three angles are much smaller than this the element is a sliv
33. it into the active session The PFG file can only be updated by explicitly exporting the graph again If an existing GraphFEKO graph WFG file is imported into POSTFEKO using File gt Import Graph GraphFEKO is called in the background to convert the graph to a PFG graph This is only possible on MS Windows It is also possible to open the WFG graph in GraphFEKO and export it to a PFG graph using File gt Export POSTFEKO graph in the GraphFEKO main menu Exporting the graph while working in GraphFEKO could yield a different number of subdivisions than using the import menu in POSTFEKO but this is the only difference in the two approaches When exporting a dB graph a power quantity is assumed The dB graph in POSTFEKO will be correct but if one then change this to a linear scale in POSTFEKO or look at the raw values in the data panel all field quantity values will be a factor of 2 to small This is due to the fact that GraphFEKO does not store this information since it does not allow linear dB convertions it does not use this info again once the graph is created 6 5 9 Loading and saving raw data POSTFEKO saves all the displays and their settings to the session file This means that no graphs or images need to be explicitly saved to be reproduced All that POSTFEKO requires is the FEK BOF and PFS files to reproduce all result visualisation In some cases for information sharing purposes it may be desirable to save the data i
34. of higher order modes Maz index n in modal expansion See description above for the max mode index m here similar meaning for the maximum mode index n EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 53 In order to model a waveguide feed by an impressed mode the cross section of the waveguide at the port location must be meshed into metallic triangles with a unique label The normal vector of these triangular patches defines the direction in which the mode is launched on the opposite side the impressed field of the excitation is zero The direction of the normal vector of the mesh elements must be consistent to the orientation of the port as such which is given by the unit vector z see the small graphics in the AW card panel above In general specific meshing rules exist in FEKO relating the triangular patch size to the wavelength see section 2 2 2 for details When meshing the cross section of a waveguide to define a waveguide port the mesh size must be small enough to capture the field distribution of the highest mode m n which is included in the expansion FEKO checks this automatically and gives a warning for coarse meshes or an error is the mesh size is too large One must then either refine the mesh just at the port or reduce the maximum mode indices used in the expansion The following restrictions apply when using a waveguide port feed e Presently waveguide ports are a
35. the layers this is the total radius of the core plus layers up to that point The highest numbered layer is outside Relative permittivity of the core layer if this field is empty Er 1 is used EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 89 o Conductivity o in of the core layer tan Electric loss tangent tan of the core layer This is an alterna tive way to specify the conductivity the two loss terms are related by tan 2 but have different frequency behaviour WEreQ If both tan and o in are empty or zero tan is set to zero Qm y Lr Relative permeability ur of the core layer if this field is empty Hr 1 is used tan dy Magnetic loss tangent tand of the core layer the complex permeability is then given by u Hour 1 j tan tan dp is set to zero if this field is empty p The mass density in kg m This parameter is only required for SAR computations see section 10 2 41 The scaling factor that is entered by the SF card is applied to the radius The parameters of the medium outside the sphere usually free space can be set with the EG card The Green s function for a homogeneous or layered dielectric sphere can be used with metallic structures treated with the MoM either inside or outside the sphere but not for example a wire from inside to outside It can be used with dielectric bodies tre
36. triangles with three different labels join at the edge EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 29 10 2 13 AI card With this two line card an impressed current source is specified The current varies linearly between the values at the start and end points see figure 10 8 Parameters New source Add to sources Amplitude Phase x y z coordinate Al Specify an impressed current segment New source C Add to sources Start Amplitude A Phase deg x coordinate y coordinate z coordinate Radius of impressed current New excitation replaces all previous excitations Additional excitation is added to previous excitations Amplitude 1 in A of the current at the Start point 71 and End point Fa Phase of the current at the start and end points in degrees Coordinates of the start and end points in m Note that all the coordinate values are optionally scaled by the SF card Radius of impressed current This parameter is optional If specified and different from zero this value gives a finite wire radius for the impressed cur rent element FEKO then assumes that the current is uniformly distributed on the wire surface and uses the exact wire integral If this parameter is not specified the current filament approxi mation is used This value is optionally scaled by the
37. 14 Example for the EL card from demo_EL pre EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 27 9 2 14 FM card This card is used to instruct the FEKO solver to calculate the solution using the Multilevel Fast Multipole Method MLFMM instead of the MoM on all structures in the simulation FM Fast multipole method Bo Box size in wavelengths Parameters Box size at fines level The MLFMM is based on a hierarchical tree based grouping algo rithm and depending on the frequency and the model dimensions FEKO automatically determines the number of levels in this tree and the size of the boxes at the finest level It is also recom mended that this default box size of 0 23 A is kept When there is no convergence in the MLFMM then advanced users might try to slightly increase or decrease this box size by setting it manually the input is in terms of the wavelength December 2005 FEKO User s Manual 9 28 DESCRIPTION OF THE GEOMETRY CARDS 9 2 15 FO card With this card an area is defined in which the surface current density is an approximation according to the Fock theory FO Define a Fock current area Perfectly conducting cylinder C Perfectly conducting sphere Triangle labels Axis start point Axis end point il Formulation of the Fock currents p Daniel Bouche formulation C Louis N Medgyesi Mitsch
38. 4 Save session as saves the current session with a new name or to a different directory It only changes the session name the names of the loaded model and result files remain unchanged Print prints the active display or graph Export to image exports the active window to an image file Load model loads a geometry model FEK file into the current session o N Q A Load results loads a result BOF file into the current session The Run toolbar provides quick access to the most used components OA 1 a 4 1 Run CADFEKO launches CADFEKO 2 Run EDITFEKO launches EDITFEKO 3 Run PREFEKO launches the model integrator PREFEKO 4 Run FEKO launches the solver FEKO If only one model is loaded or a 3D visualisation window which displays a single model has focus the component is started with the corresponding model Otherwise POST FEKO will prompt for a model For some components optional parameters can be specified using the Run Solution options menu item See also Chapters 7 and 8 The Advanced fields on these dialogs allow manual entry of the options as would be done after the filename in a command line December 2005 FEKO User s Manual 6 4 WORKING IN POSTFEKO 6 3 Displaying the geometry and model validation A new 3D view window is created by pressing the Add a new 3D view button on the main toolbar Each 3D window can only show one model geometry and results as shown in the Filename fi
39. 4 30 RM card 9 84 rotate 6 4 geometry 4 24 9 91 model view 4 5 parts 4 26 plots 6 13 point 9 96 workplane 4 8 ruled surface 4 27 run 4 46 from GUI 5 4 S parameters 10 117 SA card 10 109 SAR 6 9 specific absorption rate 10 109 save as UNIX 5 3 model 4 4 4 5 scale 4 24 geometry 9 88 9 91 Parasolid 4 21 units 4 47 search for elements 6 7 secfeko 3 1 segmentation parameters 9 52 rules for 2 5 segments 9 4 arc 9 14 coating 10 63 creation see geometry cards definition 2 2 helix 9 31 radius 4 36 4 38 selection and cutplanes 4 35 edges 4 36 in 3D view 4 35 items 4 34 mesh elements 4 36 multiple 4 35 toolbar 4 35 series adding 6 12 calculations 6 12 server licence 3 2 sessions POSTFEKO 6 1 SF card 9 88 shells 4 31 short cut keys 4 49 show axes 6 6 calculation points 6 6 excitations 6 7 Green s functions 6 6 loads 6 7 single item 4 6 4 10 4 11 toolbar 4 3 transmission lines 6 7 sides triangles 4 44 simplify 4 29 SK card 10 111 skin effect 10 111 slivers removing 4 42 snap 4 8 solid bodies 4 31 solid geometry 4 18 solids and shells 4 31 4 47 solution 5 4 options 4 46 solving 4 46 sources 10 6 Hertzian electric dipole 10 18 impressed line current 10 23 10 29 10 49 incident plane wave 10 9 magnetic dipole 10 19 magnetic ring current 10 14 1 8 microstrip line 10 26 patch feed pin 10 16 radiation patterns 10 38 s
40. 4 4 selection 4 36 view operations 4 9 union 4 26 units 4 47 updates 5 5 UT card 9 98 UTD 6 9 9 98 cylinder 9 100 polygon 9 80 UZ card 9 100 V axis 4 6 4 16 1 9 validation zoom model view 4 5 geometry 4 33 ZY card 9 105 value series 6 12 6 14 variables 4 13 4 15 environment 2 22 in point names 7 10 in PRE file 4 47 memory allocation 2 16 predefined 2 16 symbolic 7 2 version 4 49 vertices editing 4 44 merging 4 41 specified location 4 38 view orientation 6 6 out file 6 17 view selected edges 4 36 views 4 4 manipulation 4 5 visibility PO region 9 101 view items 4 9 voltage source on a node 10 13 on a segment 10 12 on edge 10 21 10 26 VS card 9 101 waveguide port 10 51 wedge as PO border 9 58 WIG files 6 15 WG card 9 104 what s this 4 5 wire curved 9 14 objects 4 21 segments 4 36 wire grid 9 104 wire segments see segments workplane 4 6 fit to geometry 4 7 transformation 4 8 zoom 6 4 2D graph 6 14 I 10
41. 5 Window menu This menu presents the standard Windows functionality to arrange or select the editor windows on the main editor area 5 2 6 Help menu In addition to providing access to the version of EDITFEKO About this menu contains shortcuts to the User s manual and Getting started manual These manuals are in PDF format and a PDF viewer must be configured on the Preferences dialog see section 5 3 The Check for updates item opens the Check for updates dialog This polls the EMSS web site and informs the user if any updates has been added since the last check Since EDITFEKO does not know if the user also have licences for other platforms it gives an update message regardless of which platform the update is intended for The update checker downloads one file containing the list of updates It does not automatically download anything else and does not send any information to the web site If Activate automatic update checking is checked EDITFEKO polls the web site each time it is started more than seven days after last checking the web site Note that this is off by default It is also possible to configure a proxy server if this is required to obtain access to the internet Click the Check button to poll the web site The Info tab applies to the update checker not the available update 5 3 Preferences in EDITFEKO Selecting File Preferences open the Configure EDITFEKO dialog The options is then grouped under separate tabs
42. 55556E 02 5 55556E 02 Time in lm JX JY JZ 0 0000000e 000 0 00000000000e 000 3 80396548298e 009 2 65565071677e 007 3 0916097e 001 0 00000000000e 000 3 29242237538e 009 1 93726675808e 006 6 1832194e 001 0 00000000000e 000 2 60940425868e 009 1 37480675066e 006 9 2748292e 001 0 00000000000e 000 4 56971413492e 009 9 30586425956e 007 1 2366439e 000 0 00000000000e 000 2 25486652232e 009 7 87315697551e 007 1 5458049e 000 0 00000000000e 000 4 83790802156e 009 1 35885783156e 006 1 8549658e 000 0 00000000000e 000 2 80525051677e 010 1 63413481451e 006 2366439e 000 5458049e 000 8549658e 000 1641268e 000 4732878e 000 7824487e 000 i 2 3 4 4 3 41120603102e 010 44230818918e 009 49040118194e 008 11922076322e 007 01439061167e 006 23064343845e 005 VALUES OF THE SCATTERED ELECTRIC FIELD STRENGTH IN THE FAR FIELD in V Factor e j BETA R R not considered EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO number Time in lm 0000000e 000 0916097e 001 1832194e 001 2748292e 001 2366439e 000 5458049e 000 8549658e 000 H H o a a O ooo 0 0 00 number Time in lm 0000000e 000 0916097e 001 1832194e 001 2748292e 001 2366439e 000 5458049e 000 8549658e 000 PrRPrRPODWO ooo 0 0 0 0 Figure 12 8 shows the response of the excitation E t in the time domain and figure 12 9 x m 2 5 00000E 01 x m 3 5 00000E 01 y m JX 00000000000e 000 00000000000e 000
43. A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 41 Note 37 points are used for Y and 73 for y to ensure that the radiation pattern is closed see also the comment above This can then be imported as a source into another model with the command AR O 1 1 37 73 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 file ffe an external ASCII file With this option the data is read from the specified external data file Each line contains 6 space delimited data fields in the following order The angle J in degrees The angle y in degrees Amplitude of the field strength E4 in V Phase of the field EJ in degrees Amplitude of the field strength E F in V Phase of the field EP F in degrees The inner loop should be with respect to the angle Y such that the order of the lines is as follows vy P Ya P Ya p vrn p v p2 Ya p2 Vi Pl after this line in the pre file This case is similar to reading an external ASCII file except that the data is read directly from the pre input file The six data fields mentioned for the case of an ASCII file must appear in the 6 columns of 10 characters starting at character 31 and ending at character 90 in the lines following the AR card When this option is selected the card dialog shows additional input fields where the user can specify these values for each point The data lines may be separated by comment lines EDITFEKO however does not support this and FOR
44. CARDS 10 35 spherical apertures PREFEKO will determine which coordinate is incremented first and write out the dipoles accordingly The dipole amplitude is the product of the surface current and the incremental area between samples In addition the amplitude of the dipoles on the sides when the Also sample along edges item is checked are reduced by a factor of 2 and those on the corners by a factor of 4 such that the effective aperture of integration has the same size as the specified aperture A fully closed surface can be created by specifying 6 planar apertures or a spherical one The surface equivalence principle can be applied to this surface by reading both electric and magnetic fields for each plane For planar apertures the user should specify 6 AP cards each using both electric and magnetic fields If separate cards are used for the electric and magnetic fields the radiated power is not calculated correctly The normal vector must point to the exterior region normally this is outward For planar apertures created form efe and hfe files the sample order determines the directions of and g which in turn determines the normal vector n s x s If this is pointing into the cube an additional 180 phase shift is obtained by setting Phase of aperture degrees to 180 This changes the sign of the field radiated by the aperture which when interacting with the remaining sources will result in the correct total fields in
45. CM 10 62 cylinders 4 18 9 105 CO 10 63 dielectric 9 20 DA 10 66 UTD region 9 100 DI 10 69 EN 10 70 DA card 10 66 FE 10 71 database browser 6 17 FF 10 79 delete FR 10 83 elements 4 41 GF 10 86 faces and edges 4 29 L4 10 92 series 6 12 LD 10 94 details tree 4 11 LE 10 95 DI card 10 69 LP 10 97 dielectric 2 14 9 65 10 69 LS 10 98 colour 4 31 LZ 10 99 cuboid cylinder 9 20 OF 10 100 cuboids 9 17 9 81 9 82 OS 10 101 for mesh elements 4 45 12 medium 4 31 4 47 sphere 10 86 thin sheet 10 111 diffraction theory 9 98 dimension scaling 9 88 dipole array aperture 10 31 direction normal vectors 4 6 4 20 4 27 4 29 triangles 4 44 disc 9 59 discrete elements 10 97 10 99 display items 4 10 settings 4 1 distorted elements 4 43 distributed load 10 94 DK card 9 17 DP card 7 10 9 19 draggin mouse 6 4 6 14 dragging mouse 4 5 duplicate elements removing 4 42 DXF file 9 42 dynamic memory management 2 16 DZ card 9 20 edges 4 11 definition 2 2 delete 4 29 length 4 36 4 40 properties 4 38 show selection 4 36 edit geometry 4 23 EDITFEKO 5 1 card editor 5 6 edit menu 5 3 file menu 5 3 keystrokes 5 10 OPTFEKO mode 5 9 options 5 5 preferences 5 5 superuser mode 5 6 variables 5 9 editor 4 48 efficiency 10 105 EFTE 10 56 EG card 9 22 EL card 9 25 electric fields calculating 10 71 elements 9 10 count 4 40 creation see geometry cards d
46. DESCRIPTION OF THE GEOMETRY CARDS 9 43 The user can import points i e vertices of polylines and start end points of lines from the DXF file The points defined in the DXF file will then be available in PREFEKO as points of the form Qxxx where xxx is a consecutive point index In addition the coordinate values of the point are available as variables in PREFEKO For example the variables q1234x q1234y and q1234z give the coordinates of point 1234 Note that points are not included by default The imported node points will have the label i e converted layer of the corresponding LINE or POLYLINE structure the layer of the VERTEX block for polylines is not used A label range selection at the IN card may be applied such that only the points with a correct layer will be imported Segments are imported from blocks defined by the keyword LINE 0 LINE 8 LAYER_01 10 0 0538 20 0 0 30 8 134 11 5 110 21 2 857 31 0 0 next keyword The group code 8 at some point below LINE indicates that the next line contains the layer name In this case the layer will be converted to label 1 The line will be imported and segmented if this label lies in the required range If not PREFEKO will search for the next occurrence of LINE Next the x y and z components of the start point follow the group codes 10 20 and 30 and those of the end point follow the codes 11 21 and 31 Here the start and end points are a y z 0 0538 0 0
47. Down gt Move to beginning of line lt Home gt Move to beginning of line lt End gt Move to beginning of file lt Ctrl gt lt Home gt Move to end of file lt Ctrl gt lt End gt EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 11 A block may be selected using the mouse or pressing lt Shift gt and using the normal movement keys If a block is selected it will be overwritten when a key is pressed The following list of hot keys are often used Hot keys Copy to clipboard lt Ctrl gt lt C gt or lt Ctrl gt lt Ins gt Cut delete to clipboard lt Ctrl gt lt X gt or lt Shift gt lt Del gt Paste insert from clipboard lt Ctrl gt lt V gt or lt Shift gt lt Ins gt Save lt Ctrl gt lt S gt Save all files lt Ctrl gt lt A gt Edit line lt F1 gt Comment line s lt Alt gt lt C gt Uncomment line s lt Alt gt lt U gt Find lt Ctrl gt lt F gt Find next lt F3 gt Find and replace lt Ctrl gt lt R gt Run PREFEKO lt Alt gt lt 2 gt Run POSTFEKO lt Alt gt lt 3 gt Run FEKO lt Alt gt lt 4 gt Run OPTFEKO lt Alt gt lt 6 gt Run TIMEFEKO lt Alt gt lt 7 gt Right clicking with the mouse on a card panel button searches for the next occurrence of that card December 2005 FEKO User s Manual WORKING IN POSTFEKO 6 1 6 Working in POSTFEKO 6 1 Introduction POSTFEKO is used to confirm the correctness of the model before running a potentially time co
48. FEKO writes all the results to an output file out In this section the parts of the output file are described 14 1 Geometric data First the geometric data is given if it has not been suppressed at the EG card For the metallic triangles the following extract is written DATA OF THE METALLIC TRIANGLES no Label xl in m y1 inm z inm edges medium x2 in m y2 in m z2 inm x3 inm y3 inm z3 inm area in m m 1 0 1 2733 0000 0000 1 2 0 1 9100 0000 0000 1 7646 7309 0000 2 3268E 01 2 0 1 1027 6367 0000 1 3 4 0 1 2733 0000 0000 1 7646 7309 0000 2 1874E 01 In the first column the number of the triangle is written In the second column the label is given followed by the medium in which the triangle is situated A 0 means that it is in free space The next three columns are the x y and z coordinates of the three corner points of the triangles In the first row of each triangle follows another list of the numbers of the edges of the adjacent triangles A positive sign indicates that the positive current direction is away from the triangle A negative sign indicates that the positive current direction is towards the triangle Below the edge numbers the area of the triangle is given in m2 Following this is an extract of the data for the edges between the triangle Whenever two triangles have two common vertices such an edge is generated DATA OF THE METALLIC EDGES with MoM triangle no points of tr no type length m m
49. For example microstrip structures could require defining dimensions within a few micrometers but this accuracy is clearly not needed when doing propagation studies around mountains CADFEKO therefore allows the specification of the model size select Geometry Extents from the main menu The extent is the same in all directions Thus only one value needs to be specified This is the Maximum coordinate which gives the largest offset in either direction along any of the three axes For example if the Maximum coordinate is 500 the entire geometry must fit inside a 1000x1000x1000 unit box centred at the origin Here unit refers to the numbers as used in CADFEKO see section 4 16 1 The model tolerance is then determined as the Maximum coordinate divided by 5 x 108 Distances shorter than this are assumed to be zero The default setting is 5E 02 and it is recommend that this be used unless the model is larger for example when modelling an automobile in mm or much smaller requiring a more accurate model and or mesh For settings other than 5E 02 exported Parasolid models will not be in the same units used in CADFEKO See section 4 6 7 The size box applies to all geometry For example an intersection between two spheres cannot be created if either sphere exceeds the size box even if the result is inside it Note that if the geometry exceeds the specified size CADFEKO will display an error The extents can then be ch
50. IN CADFEKO Find Unconnected geometry edges finds and selects all the edges of the selected parts that are free not attached to any face or attached to only one face If this operation selects an edge that seems to be connected to multiple faces it means that there is more than one edge at this location and that the faces do not make electrical contact This usually indicates a problem in the model 4 10 Assemblies Assemblies are used to organise the geometry They become part of the geometry structure and are shown as the first level under Geometry in the tree To create a new assembly select the required items right click in the tree or 3D view and select Assembly Create Only parts displayed objects can be added to an assembly Mesh and geometry parts cannot be added to the same assembly Items are moved between assemblies by selecting Assembly Move to in the pop up menu Similarly Assembly Move out moves the selected items back to the root level An item cannot be in two assemblies at the same time Deleting an assembly removes the assembly and its contents from the model Similarly selecting an item in an assembly and pressing lt Del gt will remove it from the model It is very different from Assembly Move out Selecting Disassemble on an assembly moves the items inside it back to the root level and deletes the assembly in effect removing the assembly without deleting the contents Operations
51. NEXT loops may be used Even when using FOR loops one may use the card dialog in EDITFEKO to generate a typical line December 2005 FEKO User s Manual 10 42 DESCRIPTION OF THE CONTROL CARDS We conclude this description with an example of a sector radiator We want to realise an ideal sector radiator which radiates 10 Watt horizontal polarisation in the angular region defined by 70 lt w lt 70 and 75 lt Y lt 105 Since the angle range of the imported pattern must be positive one may define separate sources for the regions 0 lt y lt 70 and 290 lt y lt 360 A more elegant solution is to define a single pattern in the range 0 lt p lt 140 and rotate it by 70 around the z axis The complete radiation pattern is defined in the following input file note that only horizontal polarisation i e E F is required Application example for the AR card Sector radiator xx No other structures considered EG 1 0 0 0 0 Set the frequency FR 1 0O 100 0e6 Specified radiated power PW 1 10 0 Define the sector radiator AR O 3 2 2 1 0 0 0 0 0 0 0 O do Theta Phi E_theta 75 0 0 0 1 105 0 0 0 1 75 140 0 0 1 105 140 0 0 1 Check Compute the full 3D radiation pattern with 5 deg stepping FF 1 37 73 O 0 0 0 0 5 0 5 0 End EN E_Phi ooo 0 0 0 70 FEKO determines a directivity of 10 1 dBi The radiation pattern is easily validated by calculating the far field as shown with
52. Note that FEKO will always use the first valid licence i e there should generally only be one valid licence on each machine Expired licences are shown in red The main table displays for each licence the hostname if available where the licence is valid the expiry date the highest allowed version one can usually use older versions with newer licence files but not the other way around the pricing category the memory limit if there is one and the number of parallel processes allowed if applicable Each licence also contains the following information click on the icon to the left of the licence to expand contract it e Machine code Expanding this item shows the machine code of the machine where this licence is valid Only shown for node locked licences e Components This item lists all the components for example EDITFEKO FEKO RUNFEKO etc which are activated in this licence e Modules The modules and extensions that are active for example if you purchased the CableMod PCBMod interface there will be an entry CableMod PCBMod on 3 2 Managing floating licences Figure 3 2 shows the licence manager with a typical floating licence If the secfeko dat file contains a floating licence server the server and port number are displayed at the top of the licence manager The Update button allows the user to update the state of the licences Note that floating licences are checked in and out as they are being used thus
53. P is acting as reference Sa 27 i R Etar 9 R Etar el G 4r R P Z Fo P Between gain and directivity there is the relation G P _ P P 14 1 DP P n 14 1 where 7 represents the antenna efficiency The last three columns of the far field ouput give the polarisation information of the scattered wave In general the polarisation is elliptical as shown in figure 14 1 The coordinates are y and and the view is in the direction of the propagation of the wave In order to evaluate these quantities let us define the magnitude and phase of the far field components as Etar 9 Ae Etar B ej i Using the abbreviation T wt por one finds the temporal field strenght vector in space as A B E t cos T a Eg cos T 8 E r r This equation describes then the polarisation ellipse of figure 14 1 One can find the minimum and maximum values of the field strength magnitude at these times A sin 2a B sin 28 A cos 2a B cos 28 1 n 3 arctan and T T2 T 3 7 Let E 7 and Ey E z2 and assuming that we have E gt E gt then according to figure 14 1 we have Emar Ej und Emin E2 The axial ratio is then defined as Emin E Emax 7 Er v December 2005 FEKO User s Manual 14 14 DESCRIPTION OF THE OUTPUT FILE OF FEKO i right min Figure 14 1 Elliptic polarisation in the far field A
54. PREFEKO cfs Session file of CADFEKO C x Native CADFEKO geometry file contains geometry and mesh etc cgm Contains the size of the residue that results from the iterative algorithm which solves the matrix equation and the number of iterations This file is only generated on request by a DA card section 10 2 24 dbg When using the UTD it is possible to request an optional output file containing a large amount of additional data and may therefore be very large see the UT card dxf AutoCAD geometry file which can be imported with the IN card PREFEKO can import arbitrary surfaces from meshed dxf files It can also import and mesh lines and polyline surfaces see section 9 2 18 edg Geometric data is taken from the fek input file where for example common edges between triangles are found This reprocessed informa tion of the geometry is saved in the edg file EG card section 9 2 12 efe File containing the electric field strengths Contains both the position and the complex components of the electric field strength vectors This file is only generated on request by a DA card section 10 2 24 fek Output file from PREFEKO serves as the input file for FEKO ffe File containing the far field data This file is only generated on request by a DA card section 10 2 24 g e Interpolation table of the electric field strengths for the Green s function of a layered sphere gfh Interpolation table of t
55. Qg S N Az COS Qg S N Qy COS Qz sin Qz COS Az COS Qg SIN Qy SIN az COS Mz COS Qy Multiplication by the rotation matrix M effectively rotates a point first by an angle a around the z axis then by an angle a around the y axis and finally by an angle az around x axis It is important to note that the second rotation around the y axis represents the EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 93 currently valid y axis and not the original one i e the one from the first rotation around the z axis Similar for the third rotation around the x axis The transformation angles as used by FEKO in this order are generally referred to as Kardan angles as opposed to the also commonly used Euler angles If the rotation shall be performed in the other order i e first around the x axis then around the y axis and finally around the z axis then one can simply use multiple consecutive TG cards But since the same rotation algorithm is also used at other FEKO cards for instance AC or AR where one cannot use multiple cards a short PREFEKO code segment shall be given here which illustrates how the angles can be converted Desired rotation angles such that we rotate first around x then y and then around z al 30 Angle in deg around x axis b1 60 Angle in deg around y axis c1 90 Angle in deg around z axis Precompute some sin and cos terms ttcal cos rad t
56. S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 109 10 2 41 SA card This card is used to control calculations of the specific absorption rate SAR in a dielectric medium SA Calculate the average specific absorption rate SAR Select calculation Calculate volume average SAR Calculate spatial peak SAR ofa 1 g cube Calculate spatial peak SAR of a 10 g cube Specify the search region Entire region By medium C By label FEM only At specified position C By layer Green s function Peak SAR in all media C Peak SAR in a single medium C Peak SAR in a medium range Include medium up to medium Parameters Select Calculation One of three SAR values which could be of interest should be selected in this group Specify the search region This group can be used to control either by medium number or by label number or by layer number for the special Green s functions which dielectric bodies are used for the specified cal culation It is also possible to specify a user defined position here for the spatial average SAR computations Average Peak SAR in all media labels layers Select this option if the selected SAR calcu lation should be done on a by label or by medium or by layer basis The whole body average SAR is also calculated Selecting the volume by label is only valid for the FEMt analysis Average Peak SAR in a single mediu
57. S1 2 S2 Figure 10 9 Location of the equivalent dipoles on a planar aperture where the Also sample along edges item is checked S3 N3 1 N2 1 N3 N2 o o o o e Oo Oo o e o o o o o e e o o o o o e e o o 3 N2 1 o o o e o e o e o Uz 2 N2 1_2 N2 1 3 N2 o o o o o o e e o N2 1 _N2 2 2 N2 o o o o o e o o o 3 4 5 6 N2 1 N2 o o o e o Oo e S1 u s2 Figure 10 10 Location of the equivalent dipoles on a planar aperture where the Also sample along edges item is unchecked December 2005 FEKO User s Manual DESCRIPTION OF THE CONTROL CARDS 10 34 Z i S2 p e ee e i cd s gt X 0 0 Figure 10 11 Location of the equivalent dipoles on a cylindrical aperture a Also sample along edges checked b Also sample along edges unchecked for Y from 40 to 80 with 10 increments and y from 20 to 80 also with 10 increments In this case the aperture increases in size in both directions when the Also sample along edges item is checked z s2 lt a S x y E s oer T gt s3 o ON E x a 0 a Figure 10 12 Location of the equivalent dipoles on a spherical aperture a Also sample along edges checked b Also sample along edges unchecked For planar apertures the data must vary first along the s direction For cylindrical and EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL
58. Select symmetry for the plane 2 0 None Electrical C Geometrical C Magnetic Label increment for the new structures Note For electric symmetry the tangential electric field is zero while for magnetic symmetry the tangential magnetic field is Zero Parameters Select symmetry for the plane x 0 The type of symmetry if any in the yz plane Select symmetry for the plane y 0 The type of symmetry if any in the xz plane Select symmetry for the plane z 0 The type of symmetry if any in the xy plane Label increment for the new structures After they are mirrored the labels of the new ele ments are incremented with the value specified in this field Label 0 is however not incremented The corresponding new elements will also have label 0 If this field is empty or set to 0 the la bels are not incremented i e the new elements will have the same label as the one they were created from All the conducting and or dielectric triangles segments cuboids tetrahedral volume elements wedges edges Fock regions and polygonal surfaces that have been declared before the SY card are mirrored Furthermore the second and third corners of the triangles are swapped such that the direction of the normal vector is retained Likewise the corners of image polygons are rearranged to retain the normal direction The first corner point of the original polygon becomes the last corner of the mirror image Sources are not mirror
59. Set proper ties for medium number this is an alternative way to specify the conductivity the two loss terms are related by tan e and have different frequency behaviour Mass density The mass density in kg m This is only required for the SAR computations see section 10 2 41 Note that for backwards compatibility with older FEKO versions where only one medium was allowed and the parameter Set properties for medium number did not exist this parameter defaults to 1 if not specified i e input field is empty If the value is set to 0 as opposed to leaving it blank it will overwrite the default free space parameters that might have been set at the EG card or at a previous GF card for the free space Green s function December 2005 FEKO User s Manual 10 70 DESCRIPTION OF THE CONTROL CARDS 10 2 26 EN card This card indicates the end of the input file It is essential and has no parameters EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 71 10 2 27 FE card This card controls the calculation of the near fields FE Calculate the near fields Electric field values y J Calculate only the scattered part of the field Coordinate system Cartesian Cylindrical y axis Cylindrical C Conical C Spherical C Specified points Cylindrical x axis Starting values x y z No of points Increment x x y y aj o
60. THE CONTROL CARDS e Scaling the matriz A A Scaling the matrix A A so that the elements on the main diagonal are all normalised to one e Block Jacobi preconditioning using inverses The inverses of the preconditioner are calculated and applied during every iteration step For performance reasons Block Jacobi pre conditioning using LU decomposition is recommended e Neumann polynomial preconditioning Self explanatory e Block Jacobi preconditioning using LU decomposition Block Jacobi preconditioning where for each block a LU decompo sition is computed in advance and during the iterations a fast backward substitution is applied e Incomplete LU decomposition Use an incomplete LU de composition of the matrix as a preconditioner e Block Jacobi preconditioning of MLFMM one level up Spe cial preconditioner for the MLFMM where additional infor mation is included into the preconditioner e LU decomposition of FEM matriz An LU decomposition of the FEM matrix is used as preconditioner e ILUT decomposition of FEM matrix An incomplete LU decomposition with thresholding of the FEM matrix is used as preconditioner e Multilevel ILUT Diagonal decomposition of the FEM ma trix Self explanatory e Multilevel ILUT ILUT decomposition of the FEM matriz Self explanatory e Multilevel LU Diagonal decomposition of the FEM matriz Self explanatory e Sparse Approximate Inverse SPAI preconditioner Precon
61. The setting for Factor for CFIE is global not per label the value read from the last CF card will be used December 2005 FEKO User s Manual 10 58 DESCRIPTION OF THE CONTROL CARDS 10 2 21 CG card Here the method used to solve the matrix equation may be chosen Normally the CG card should not be used FEKO has been written to chose the optimal solution technique and also the corresponding pre conditioners and options etc for different types of problems automatically These algorithms should work in all cases but for specific MLFMM or FEM configurations which rely on iterative solvers might not be optimal Thus for these solutions advanced users might after consultation with FEKO technical support apply the CG card in such special cases But one should realise that convergence of the iterative techniques cannot be assured and also when using an inappropriate preconditioner the memory requirement might be much higher than required Also users should take care to reconsider any CG card settings in models that are derived from models containing the CG card CG Set preconditioner and solver options Gauss elimination LAPACK routines Maximum number of iterations A Stopping criterion for residuum i Stop at maximum residuum e Fietchersmen o Block size LU Block Jacobi sis Threshold value for LUT Fill in level per row Lf Stabilisation factor FEM a Save read preconditioner No data files no
62. These are added after the argument mpi options For example on a ScaMPI cluster assuming FEKO_WHICH_MPI 6 the call runfeko example_08 np 6 mpi options immediate_handling threaded smtrace 5 6 all on one line is interpreted internally and FEKO is executed with the command opt scali bin mpimon export env immediate_handling threaded smtrace 5 6 opt feko bin feko csv example_08 hosti 4 host2 2 Note that host1 and host2 are examples only the actual information is taken from the machines file 8 2 3 Running on a remote host The FEKO kernel can also be started on a remote host with automatic file transfer For instance the user can run the FEKO user interface on a Windows PC but start a sequential or parallel FEKO job directly from this user interface on some other remote workstation or cluster This remote launching is also cross platform e g one can launch a remote job from a Windows PC on a UNIX workstation December 2005 FEKO User s Manual 8 6 THE FEKO SOLUTION KERNEL Please see the detailed installation and setup instructions in the Getting started manual For instance SSH must be available with public key authentication After the setup using remote launching is simple On Windows and Linux this remote launching facility can be used directly from within the GUI components CADFEKO EDITFEKO or POSTFEKO There as described above for the parallel launching open the Solution options dialog fro
63. Write far fields The far field is stored in a ffe file Write currents The currents are stored in a os file Log residue The residue from the iterative algorithm used to solve the matrix equation is stored in a cgm file Write S parameters The S parameters see the SP card are written to a file in Touch stone SnP format The n here gives the number of ports Write spherical wave expansion A spherical wave expansion of the far field as com puted by FEKO is exported to an SWE file extension sph which can be imported into GRASP from TICRA code for re flector antenna modelling Note that the far field computation with spherical wave expansion must be requested subsequently see the FF card in section 10 2 28 More than one DA card is allowed in one input file Thus using the following sequence of control cards with the appropriate options only certain blocks will be saved to the data files DA xx Write near fields on FE DA Write near fields off FE EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 67 With this sequence the electric fields calculated with the first FE card can be written to the efe file but not those of the second FE card The structure of the data files is described below efe file When calculating the electric near field in Cartesian coordinates there are columns with the position in x y and z as well as the field co
64. Zz as shown in figure 10 27 For most practical applications the transmission line will be lossless resulting in a real characteristic wave impedance For this lossless case the reflection factor dv Lav ZL d Za v T ZL December 2005 FEKO User s Manual 10 108 DESCRIPTION OF THE CONTROL CARDS is taken into account when calculating the incident power at the feed point The total incident power is given by and the reflected power by lov 1 o To ensure that the total incident power is Po the power is scaled with the factor Pro ov Pow Faw o _ 2 y z N Pow 2 ene and the currents with the factor y s As before the total reflected power Pou s Poy s Y Pay ee lov reduces the gain of the antenna If we have a lossy transmission line then forward and backward travelling waves can still be identified on such a transmission line but a proper definition of power associated with such a wave is not possible since due to the losses the power will constantly change along the length of the transmission line It is also questionable whether using the PW card with a lossy transmission line makes any sense But it has still been implemented and then the forward travelling power Pp is interpreted as the maximum available power at the end terminals of the transmission line For a lossless transmission line this formulation is compatible with the above equations EM Software amp Systems
65. a e a ee a Oe eS 4 49 4 19 hormont yS s c ae e a bb ied AA h dh h ioi di oah 4 49 5 The editor EDITFEKO 5 1 ol Toolbars oa co ei rer poa aa aaa i a ES ED 5 2 Sl File control toolbar sid coce wee ee es 5 2 5 1 2 The edit and window toolbars 5 3 5 2 Menuitemsin EDITFEKO 0 4 5 3 dal PUSIERA ao 0 EA a dl a OR A e tetra 5 3 paa EO EA A de O 5 3 EM Software amp Systems S A Pty Ltd December 2005 CONTENTS e 5 2 3 Geometry cards and Control cards menus 5 4 5 2 4 A AAA 5 4 5 2 5 Widow TEI oosa a ce aaa ss RE a e A E 5 5 5 2 6 o Ss ae Bae ok hh So ee eh Gi a Ss A A EE A 5 5 5 3 Preferences im EDITFEKO 2 6 05 666444 dada ee ee 5 5 5 3 1 Appearance Tab a a a a 5 6 Dz Options tab c se a t tus ce be eee aeee bee baad 5 6 Dl PREPEKO mode so vag odd ee ee ee Se ee RR Se eek 5 6 5 4 1 Generating put Cards os ac cadro eaa a bawi 5 6 5 4 2 Vara be GWE o o s oads a i e a SORE ORO ee t 5 9 bo TETFERC mode o oe ca nni a eae Da ag Ad a N 5 9 5 5 1 Patameter tab sa d ee o 13 5 9 5 0 2 Penalty function Tab ss eee eR a ee 5 10 B D Optimisation tab ee 5 10 Boe Aim iunction tb occiso LL Oe os 5 10 5 6 Important keystrokes gt aa 44 48405505 2 a PE eS 5 10 6 Working in POSTFEKO 6 1 Gl IMAN cocidas AAA Ad Se E 6 1 6 1 1 starine POSTFERKO oo racea ee RS DG RR MKS 6 1 62 POSTFERO ov tvieW sasad ke etn oe ER RO ee eS 6 2 6 3 Displaying the g
66. above the top or below the bottom ground plane If a top ground plane is added the para meters of layer 0 the upper half space are ignored If there is no ground plane at the bottom the last layer is infinitely thick Number of layers Number of layers in the substrate layer 0 the upper half space is not included in the number Thickness Thickness of the layer is scaled by the SF card Er Relative permittivity r of the layer O Conductivity o in of the layer EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 91 tan Electric loss tangent tand in the layer lir Relative permeability ur of the layer tan u Magnetic loss tangent tan 6 in the layer the complex permeabil ity is given by p Hour 1 j tand p The mass density in kg m This parameter is only required for SAR computations see section 10 2 41 Z value at the top of layer 1 The value of the z coordinate at the transition between layer 0 and layer 1 As indicated in the figure of the card layer 0 is the upper half space layer 1 is just beneath this etc Losses in any layer may be specified through assignment of either the conductivity o or by the electric loss tangent tan Only one of these input values may be used the other must remain empty They are related by tan oe It should be noted that inside a frequency loop with varying w the first option is constant while se
67. and click and drag with the left mouse button at the required location Alternatively hold lt j gt Shift while clicking and dragging While the mouse is dragged a red dotted line indicates the are that will be enlarged once the mouse button is released After zooming in on the graph a new Reset zoom pan button is shown below the Zoom box button Click this to return to the default view Note that when autoscaling for an axis is enabled the settings are adjusted while zooming for example the number of digits in the labels may be increased When autoscaling is off this is not done automatically but left to the user Clicking and dragging while hoding down lt Ctrl gt pans moves the graph This is partic ularly useful in connection with zooming so that the visible window of an enlarged view of a plot can be moved around 6 5 7 Value series description A value series is a data series that stores its own values rather than referring to a result file The series is simply stored as a series of numbers and does not necessarily relate to any specific type of data In contrast when data is read from a BOF file POSTFEKO can determine the data type A user may wish to convert a series to a value series when the integrity of data in a BOF file is not ensured for instance a user may want to store the graph of the input impedance of an antenna versus frequency for a few iterations of the antenna design The same model is used for e
68. and this should only be done based on physical considerations Visibility information The visibility information related to multiple reflections can be saved to reduce the computation time for future runs There are four options that can be selected with respect to saving the multiple reflection visibility information e No vis files normal execution Visibility information is not used or stored the default behaviour e Save visibility to a vis file The PO visibility information is stored in a vis file for later reuse e Read visibility from a vis file The PO visibility informa tion is read from the vis file i e the calculation of the visibility information is skipped For large models this can result in considerable time saving e Read vis file if it exists else create it If a vis file exists the PO visibility information is read from this file Other wise the information is calculated and saved in a vis file for later use The physical optics PO approximation can only be used for certain structures Struc tures where the antenna is situated in front of a reflector are well suited Then PO can be used for the triangles that form the reflector This results in a large reduction in computational time and memory for electrically large objects Note that the ray tracing options and the number of reflections can be specified on a per label basis by using multiple PO cards All other parameters can only be spec
69. arguments in radians cos tan cot arcsin trigonometric inverse functions results in radians arccos arctan arccot atan2 atan2 y x yields arctan y z in the range 7 7 deg converts radians to degrees rad converts degrees to radians sinh hyperbolic functions cosh tanh log logarithm to base 10 In natural logarithm exp exponential function sqrt square root abs absolute value step step x is 1 when x gt 0 otherwise it is 0 ceil rounded upwards floor rounded downwards min min a b or max a b gives the minimum maximum of max the two arguments If there is an error in the expression an error message will be displayed at the bottom of the dialog The variable can only be added when the expression is valid The Evaluate button evaluates and tests the validity of the expression without closing the dialog The result is maintained until the next time the expression is evaluated it is not updated automatically when the expression is changed Variables can be changed by double clicking on the variable itself or by right clicking and selecting Properties CADFEKO will display a circular dependencies error if a variable is changed in such a way that it depends on itself All items depending on the variable will be updated automatically If this results in invalid geometry for example a sphere radius that becomes zero or an intersection or split that becomes empty an e
70. be applied to both open and closed bodies The CFIE can be used only in connection with closed objects and the advantage is that the conditioning of the system of linear equations is better In particular in connection with MLFMM the convergence can be improved if the CFIE is used for closed parts of an object EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 57 For the CFIE in addition to the fundamental restriction that the surface must be closed these further conditions apply The normal vector must point outwards i e from the closed field free region into the domain of interest where there are sources and fields shall be computed Using symmetry in order to reduce the memory or run time is not supported in FEKO it will be switched off automatically The CFIE formulation for the MoM cannot be used together with the MoM PO MoM UTD or MoM FEM hybrid methods The CFIE formulation can be used only with the free space Green s function i e using the spherical or planar multilayer Green s functions is not supported When using the CFIE one cannot have dielectric bodies in the same model and also the CFIE surfaces must be perfectly conducting no coating or Skin effect etc Using a ground plane BO card is not supported Note that multiple CF cards can be used in order to specify for instance that the CFIE shall be used at multiple distinct labels which do not form a range
71. be unambiguous i e if possible only one triangle must have this label If there is more than one triangle with this label then only one will be fed Alternatively when se lecting the item Set source position the feed edge is determined by specifying its Cartesian coordinates in the Coordinates of edge centre These coordinates are in m and optionally scaled by the SF card The edge must lie between two triangles or between a triangle and a ground plane or UTD plate Magnitude of source Absolute value of the voltage Uo in V Phase of source Phase of the voltage Uo in degrees If two triangles are connected to the edge the basis function between these triangles is excited The vector direction of the voltage source lies in the same direction as the basis function associated with this edge This is the direction of the current flow through the edge The internal EMF electromagnetic force of the impressed voltage source is in the opposite direction December 2005 FEKO User s Manual 10 22 DESCRIPTION OF THE CONTROL CARDS In certain special cases there may be only one triangle connected to the edge If the edge lies in the plane of a polygonal UTD plate or a PEC ground plane specified with a GF or BO card the excitation is placed on the appropriate basis function connecting the triangle to the plate plane The positive feed direction is then towards the edge EM Software amp Systems S A Pty Ltd December 2005 D
72. biological structure then one might consider switching to first order only to reduce the number of unknowns EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 2 17 HE card With this card a helical coil consisting of wire segments can be created Parameters i S2 S3 Connect helix Coil orientation Number of turns HE Specify a helical wire coil 5 s1 s2j saf ag helix to axis with additional segments Yes C No Be orientation Right handed C Left handed Number of turns Maximum segment length IV Set tapered wire radius Radius at start point of wire Radius at end point of wire Scale second half axis with The start point of the coil s axis The end point of the coil s axis The start point of the windings Create connections from the two ends of the coil to the axis at points S1 and S2 See also left side of figure 9 15 If the connec tions are not generated point S3 is a connection point See also the right side of figure 9 15 Indicate whether a right or left handed coil should be created In this field the number of turns for the helix is entered It need not be an integer number Maximum segment length Maximum length of the segments that are used for the windings Set tapered radius in m is scaled by the SF card If this parameter is left empty the value specified with the IP car
73. by activating the Show hide normals button on the 3D view toolbar Normals are then shown as lines with a red tip Reversing normals of triangles on dielectric boundaries can adversely affect the consistency of the model CADFEKO tries to keep the model consistent For example if the normals of all triangles in a given label are reversed CADFEKO swaps the dielectric media on the two sides However if only some triangles are modified CADFEKO cannot ensure consistency and it is up to the user to ensure that the model is consistent 4 13 12 Setting mesh properties Ideally properties should be set on the geometry as this is copied to the mesh each time the geometry is meshed However it is possible to set properties on the mesh Select Edit Properties to open the appropriate Mesh properties dialog set Note that medium properties can only be set if the selection contains mesh labels rather than elements For tetrahedra only the medium can be specified For triangles the medium is specified on each side If either medium is a dielectric and the other is not solid metal then the triangles defining the border can be specified as metallic or not For segment labels both the segment radius and the surrounding medium can be specified but when the selection contains individual segments only the radius can be specified Specifying the media on the mesh elements should only be required for imported meshes If multiple elements labels with dif
74. card which medium is on which side of the triangle as determined by the normal vector For example if the ME card is used to specify that the normal vectors of the triangles point from medium 5 to medium 2 then the application of the CN card will effectively change which medium lies on which physical side of the triangle EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 17 9 2 9 DK card This card is used to create an eighth of a sphere meshed into cuboidal elements for solutions using the volume equivalence principle in the MoM The meshing parameters as set at the IP card are used and the medium as set at the ME card is assigned to all created cuboidal elements DK 1 8 sphere of dielectricimagnetic cuboids i gW s2 s So l sf Maximum cuboid edge length sd Choose the medium Dielectric C Magnetic C Both dielectric and magnetic FF Old format with medium parameters Parameters iol The centre of the sphere S2 53 S4 Specify the three directions S1 52 S1 53 and S1 S4 that form the border of the eighth of the sphere They must be perpendic ular to each other and all three must have the same length the sphere s radius Maximum cuboid edge length The maximum side length of cuboids along the curved edge in m can be specified This value is scaled by the SF card If left empty the value specified with the IP card is used Cho
75. command runfeko example_08 where example_08 pre must be an existing input file RUNFEKO executes PREFEKO if the fek file is missing or older than the pre file and then executes the appropriate FEKO solver sequential or parallel etc RUNFEKO accepts the following optional pa rameters see also section 8 2 2 for additional options to launch and control the parallel version of the solver or section 8 2 3 for remote launching of FEKO execute prefeko Always execute PREFEKO even if fek file exists is newer than the pre file use mpich Force parallel UNIX versions to use the MPICH version of FEKO even though the default could be ScaMPI or Score or another MPI implementation version Print the version information and then exit priority x The value x specifies the CPU usage priority of the FEKO run 0 idle 1 below normal 2 normal 3 above normal and 4 high If not specified the default is 2 This option might not be available for specific systems or specific FEKO versions then it is just ignored prefeko options All options following this if one is used up to the next xxx options are passed to PREFEKO December 2005 FEKO User s Manual 8 2 THE FEKO SOLUTION KERNEL feko options All options following this if one is used up to the next xxx options are passed to FEKO adaptfeko options All options following this if one is used up to the next xxx options are passed
76. corner points which define the waveguide sides s from 1 to S2 and s from S1 to S3 The direction in which the mode is launched is given by z ti X ta Circular A circular waveguide cross section is used The point S1 denotes the centre of the circular port and the point S2 specifies the radius and start point for the angular dependency A further point S3 must be perpendicular above the centre of the circular plate such that the direction from S1 to S3 indicates the direction in which the waveguide modes are launched December 2005 FEKO User s Manual 10 52 DESCRIPTION OF THE CONTROL CARDS Coaxial Here a feed of a coaxial waveguide with circular cross sections of both the inner and outer conductor can be specified The point definitions are the same as for the circular waveguide except that an additional point S4 must be defined between S1 and S2 which specifies the radius of the inner conductor TE mode If this option is checked a mode TEm n also referred to as Hm n is used as excitation TM mode If this option is checked a mode TMm n also referred to as Em jn is used as excitation TEM mode Tf this option is checked only available for the coaxial waveguide since such modes don t exist in rectangular circular waveguides a TEM mode is used as excitation Mode index m The index m of the TEm n or TMm n mode which is impressed at the port Note that for a rectangular waveguide the index m is related to
77. defining excitation cards Currently only Al A2 A3 A4 AE and AW sources are supported Al A2 and A3 sources must be selected by label not with position and unique labels must be used i e no other segments or triangles may have a label which is used for a port If the amplitude of any port is set to zero it will be used as a receive port or sink but not as a source For example if only S21 and S11 are required for a two port network one may set the amplitude of the source defining port 2 to exactly zero Then S12 and S22 are not calculated in some cases this may save considerable computation time The load impedance for each of the port sources can be specified at the source itself If no such impedance was specified the System impedance Ohm value specified with the SP card will be used if this value is not specified it defaults to 50 Q This load impedance will be added automatically to each port The only exception here are waveguide ports AW card where S parameters are related directly to the corresponding waveguide impedance It must be noted that except for waveguide ports the SP card adds load impedances to all the ports For Al A2 and A3 sources it uses LZ type loads if no transmission line is connected to these segments otherwise the shunt admittance of the transmission line is set directly for A4 sources it uses L4 type loads and for AE sources it uses LE type loads If any similar loads were applied to the sour
78. definitions of S and Z polarisation can be found in section 6 7 14 7 S parameters If S parameters have been requested with an SP card FEKO prints different tables to the output file The first lists the impedance at each port all sources that are active when the SP card is processed are considered as ports LOAD IMPEDANCES AT PORTS port impedance in Ohm 1 5 00000E 01 2 1 00000E 02 3 5 00000E 01 Then the S parameters are listed for each source as shown below Note that sources whose amplitude are set to exactly zero are only used as sink ports i e they are not excited and no such block is created All the ports are loaded and FEKO therefore also writes this information to the output file The second data line below gives S21 or the coupling to port 2 when port 1 is excited In the second block here under the first line gives S13 or the coupling into port 1 when port 3 is excited December 2005 FEKO User s Manual 14 16 DESCRIPTION OF THE OUTPUT FILE OF FEKO SCATTERING PARAMETERS ports magnitude phase sink source real part imag part linear in dB in deg S 1 1 6 14622E 02 3 53596E 01 3 58898E 01 8 90 80 14 S 2 1 3 61992E 03 5 42992E 03 6 52594E 03 43 71 56 31 S 3 1 1 46490E 03 1 73598E 02 1 74215E 02 35 18 94 82 SCATTERING PARAMETERS ports magnitude phase sink source real part imag part linear in dB in deg S 1 3 1 31791E 03 1 74114E 02 1 74612E 02 35 16 94 33 S 2 3 9 17744E 01 1 08299E 01 9 24112E 01
79. documentation for information on OpenGL support Note that some cards only support OpenGL at a certain colour depth While CADFEKO may work without trouble on a large number of graphics cards the following cards have been tested and are recommended MS Windows ATI Radeon 800X Pro Radeon 9000 Radeon 9800 Pro Radeon 9600 XT Radeon 8500 Radeon X600 XT PCIe Fire GL Z1 VPU FGL9500 Fire GL V3100 PCle NVidia Quadro 4 900XGL Quadro 4 980XGL PNY Quadro 4 580XGL PNY Quadro FX 1100 PNY Quadro FX 3000 PNY Quadro FX 1300 PNY PCIe GeForce PCX 5750 Jaton PCIe GeForce 6600GT Jaton PCIe GeForce 6800 Ultra Gigabyte PCIe GeForce FX 5200 GeForce FX 5700 Gigabyte GeForce FX 5950 Ultra PNY 3Dlabs Oxygen GVX1 Linux ATI Radeon 800X Pro Radeon 9800 Pro Radeon 9600 XT In addition CADFEKO can be configured to allow accurate rendering on most graphics cards Select Options Rendering from the main CADFEKO menu to open the Ren dering options dialog see section 4 3 Some cards may give better but slower results using software rendering Face displacement allows a trade off between edges appearing broken and supposedly hidden lines being visible EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 3 4 2 CADFEKO overview The CADFEKO display shown in figure 4 1 contains in the def
80. down the corresponding items are shown Hiding the workplane also hides the grid but not the other way around The View mesh edges button on the main tool bar see section 4 11 also controls element visibility but it is relevant to the selected items and applies to all 3D views simultaneously Showing hiding individual items see section 4 3 6 overrides the settings on the 3D view toolbar The down arrows next to the Geometry and Mesh view buttons select the type of view In the Default view all parts are drawn with solid faces and the same colour If Colour by medium is selected each medium is displayed with a separate colour as indicated in the list under Media in the tree see section 4 8 Surface mesh elements are coloured on each side according to the medium on that side of the face For example when viewing the mesh of a dielectric object the entire object will have the free space colour when viewed from outside The different colours of the internal media will only become visible if cutplanes are introduced Since the user can set arbitrary colours on each side of a triangle this colouring scheme is required to verify that the media was specified correctly The same applies to geometry faces between different dielectic media External geometry faces are however displayed using the colour of the internal medium Hence a dielectric object will be displayed with the dielectric colour also when viewed from outside If Wire frame
81. effective surface impedance When used with PO it is not required that u e or e 4 e In this case the order of the layers is also significant The layer on the side that the triangle normal vector points to is specified in the first line with the remaining layers following in sequence 10 2 42 3 Triangles as a thin anisotropic dielectric sheet This option is very similar to Triangles as thin isotropic dielectric sheet but the layers are anisotropic The principle direction in each layer is defined by the angle a Angle of principle direction field relative to the projection of the vector Reference direction field onto the plane of triangle Here a is measured in the mathematically positive sense with respect to the normal vector of the triangle POSTFEKO can be used to display the fibre direction and visually check that the input file is correct In this case the card line is followed by an additional line for each layer The medium properties in the principle direction is different from those in the orthogonal direction which lies in the plane of the triangle and orthogonal to the principle direction Parameters Relative permeability The relative permeability ur which is the same for all layers Magnetic loss factor Magnetic loss tangent tan the complex permeability is then H opr 1 j tan a which is the same for all layers Reference direction The x y and z components of the vector used to define the
82. file One can now process and view such pre files For example in a pre file which will be optimised with respect to the variable a one may use 11if not defined a then a 200 0e 3 l endif The order of precedence is lower levels are evaluated first is OR AND and lt gt gt lt gt and lt and and and when used as sign function calls single number expressions in brackets December 2005 FEKO User s Manual 7 6 THE PREPROCESSOR PREFEKO Some variables are predefined in PREFEKO but may be overwritten by re assignments These are Name Value Description pi 3 14159265358979 The constant 7 epsO 8 85418781761 107 2 Dielectric constant o of free space mu0 An 10 7 Permeability y of free space c0 Tes The speed of light in free space z 0 The intrinsic impedance of free space true 1 Used for logical true false 0 Used for logical false There are three other special variables x y and z which are very useful for the connection of complex wire structures The three variables specify the Cartesian coordi nates of the end point of the wire segment most recently defined This enables the correct and easy connection of a straight wire to a curved length of wire as the next extract from an input file demonstrates CE shards DP A x ly z tz z 0 5 DP B x ly tz BL A B The following example demonstrates the use of variables A diel
83. import points from the PATRAN file similar to importing points from FEMAP or NASTRAN files The points defined in the PATRAN file will then available in PREFEKO as points as if they were defined by DP cards of the form Txxx where xxx is the index of the grid point This may be used for example to attach additional structures to the geometry In addition the coordinate values of the point are available as variables in PREFEKO For example the variables t1234x t1234y and t1234z are set to the coordinates of the point with index 1234 Note that points are not included by default Since points do not have an associated property ID points are imported irrespective of their label December 2005 FEKO User s Manual 9 50 DESCRIPTION OF THE GEOMETRY CARDS 9 2 18 11 Import ANSYS CDB file PREFEKO also supports importing geometry from ANSYS cdb files By default when exporting such files from ANSYS the BLOCKED option is used PREFEKO only un derstands this BLOCKED syntax the UNBLOCKED version is not supported Also regarding the element type only the ANSYS element types 200 filaments triangles tetrahedral elements and brick elements as well as element type 16 pipe16 wire with a finite radius are supported IN Include an external file Import ANSYS CDB file y Y Include segments IV Include triangles FF Include node points F Include cuboidal volume elements F Include only node points for imported triangle
84. in the tree allowing access to the part without points but uses the name of the parent object since there is only one parent Multiple parts can be projected onto another part by selecting them activating the Project operation and then selecting a target part to project onto This sequence is similar to the subtract operation Also similar to the subtract operation all the projected parts appear as parents of the resulting part i e they are no longer present as individual parts of the model All the edges of the selected parts are projected onto the faces of the target part Any part curves surfaces and solids can be projected onto any part containing faces Spheres do not have edges hence projecting a sphere has no effect other than removing it from the model Where the projected edges form closed paths new faces are created The projection direction is determined from the normals of the faces of the target Pro jecting edges onto convex curved target faces will thus tend to reduce their size and or perspective Convex surfaces may also shadow other surfaces in that all points on the projected edge may project onto the curved face even though it seems as if it should also project unto another face Finally edges are only projected onto the normal side of faces Edges where the projection crosses itself or turns back on itself are not allowed EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 29
85. is used to control the settings of the graph and how the series are displayed 1 Series data opens a panel where the user controls the data for each series Typical options that would be available on this panel include field compo nents for near fields or which part real imaginary magnitude or phase of the data to plot The Unwrap phase option should only be used for phase calculations If it is checked POSTFEKO tries to avoid 360 jumps by adding integer multiples of 360 mala in ia 2 Series settings opens a panel that is used to specify graph settings with respect to each series such as plot colour markers etc This panel is also used to specify offsets and scaling factors 3 Graph settings panel controls the global graph settings such as Polar Cartesian graph title and footer information For Polar graphs checking Vertical displays the graph with 0 at the top rather than to the left If Mirror is checked the angle runs clockwise rather than counter clockwise 4 Left axis panel controls all the settings for the left axis These settings include linear log dB selections normalisation and captioning If Add unit is unchecked POSTFEKO does not try to a add a unit it is then the user s responsibility to do so in the axis caption 5 Bottom axis panel controls all the settings for the bottom axis These settings are very similar to the left axis 6 Zoom box activates the mouse to specify a
86. licence while just setting up your model then nobody else can use this and you could possibly have used one of the GUI licences Finally note that all licence requests from the same user and the same machine will December 2005 FEKO User s Manual 3 4 THE LICENCE MANAGER use the same licence Thus if you set a preferred licence while you have other FEKO components running the licence manager does not require a licence the new licence will only be used once you have closed all components and opened a new one 3 2 2 Managing the server While a licence is checked out nobody else can use that licence It may happen that a user has say CADFEKO open on his machine while he is on leave or that the licence is urgently needed for another run and the user is not available to stop his run The licence manager therefore allows checking in a licence such that it becomes available again Right click on the licence and select Check in licence from the resulting pop up menu or click on the licence and select Server Check in licence from the main menu For security reasons this check in operation is allowed only for users with administrative priviledges Windows or the root user UNIX or the user who has initially checked out this particular licence If a licence is checked in all components using that licence will fail the next time they check the licence server In the case of the solver components RUNFEKO PREFEKO FEKO ADAPTFEK
87. maximum of 5 characters of the point X Y Z coordinate Cartesian coordinates of the point in m is scaled by the SF card Nurb control point weight The weight of the control point when this point is used with the NU card NURBS surfaces If the field is empty it defaults to 1 In addition to its coordinates each point is also assigned the current label see LA card so that a group of points can be selected by label for example when moving points with the TP card Point names may use the characters a z A Z 0 9 and the special character _ and no distinction is made between upper and lower case characters Thus Pia and p1A refers to the same point In addition when defining or using node names simple variable names of the form A i are allowed The algorithm is that if a hash sign is found in a node point name this hash sign and everything that follows is interpreted as a variable string evaluated and rounded to the nearest integer Thus if we have k 15 and use or define a point P k then this is equivalent to using P15 as point name The length of the node name string before and after expansion is still limited to 5 characters For instance it would now be possible to define the points P1 to P20 inside a loop for k 1 to 20 DP P k Inext Unlike most other geometry cards the DP card as well as the TP card may also be used in the control section after the EG card of the pre file This allows defining
88. must be chosen as the AC card then results in a frequency loop and currents with different EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 25 frequencies cannot be superimposed If it is not chosen PREFEKO will give an error The frequency is defined in the rsd file thus the preceding FR cards are ignored when processing an AC card All commands following the AC card in the FEKO input file for example FF FE OS GF BO are processed within a frequency loop through all the frequencies in the rsd file The loop is terminated by any of the following three cards these cards are not included in the loop they terminate e AC importing a new rsd file or using the flag Iz 0 e FR manually setting a new frequency e EN end of the FEKO input file For example if a CableMod file must be read and the near field calculated for each frequency the input file may look as follows AG sors Read the rsd file PE oso Calculate the near field EN End However if one wants to analyse for example a metal plate which is excited first by an impressed line current and then also by a plane wave in each case the near fields and the currents on the plate must be written to the output file the input file would be Excitation by a line current AC Read the rsd file PE fae Calculate the near field OS Qutput the currents Excitation by a plane wave
89. oa e a ee A ee 12 8 12 6 A TIMEFEKO example ociosa 25 SEA DH 12 9 13 The program ADAPTFEKO 13 1 ISL DESCUBRO cocida ai ee we 13 1 132 Running ADAPTFERO 2 2 42 2506666 eb bee ee os 13 1 133 The pre input fle 0 6444 bee bbb dade ee aa es 13 1 134 ADAPTFEKO example ua ee ae Pee ae Gee a 13 2 14 Description of the output file of FEKO 14 1 14 1 Geometric data cw i 14 1 taa ERI o e oe s ecg ok a A a w E 14 7 143 Currents and charges ia a4 2 6 aaa Re a da Oe eG 14 8 14 4 Finite conductivity 4 4 0608656044444 ae e E 14 9 14 5 Near fields ob ewe eed a EES 14 10 BA Eat io as be RB Be PE es rer eed AAA ORES 14 11 147 OPa ca 4 a a a i AO RE AC eS 14 15 14 8 Computation time and peak memory 14 16 15 Copyright notices and acknowledgements 15 1 15 1 Copyright to Vorom l 444 2 2 06685084 Aaa ELK DS 15 1 15 2 Copyright to SuperLU 2 2 4 sas ee eee ee eee 8 15 1 153 Tapert OF BOWE lt eiiie kee EEN ELA EEG Ee eG 15 2 154 OU project usage o cr a a SS ee Ses 15 3 16 6 HOOPS and Parasol oc ak ago ce Spor ee ae BOR Ee Se 15 3 158 Meshi ou RA Me ee a Re ee 15 3 Index I 1 December 2005 FEKO User s Manual INTRODUCTION 1 1 1 Introduction The name FEKO is an abbreviation derived from the German phrase FE ldberechnung bei K rpern mit beliebiger Oberfl che Field computations involving bodies of arbitrary shape As the name suggests FEKO can be used for various types of electromagnetic field
90. occurrence starting from the current cursor position of the associated card is found Note the Goto line option which is very useful to find lines reported by PREFEKO PREFEKO always reports the line number where errors occur The Comment and Uncomment item allow the user to comment out blocks of text or remove the comments This is often useful when debugging large files The comments are inserted as followed by a space and only removed if this sequence is present For example in the lines x k Select the label LA 1 k Next comment the comment characters will not be removed from the third line using this function It was also not generated by the Comment function These commands are also available using the hot keys lt Alt gt lt C gt for Comment and lt Alt gt lt U gt for Uncomment or by right clicking in the editor and selecting from the resulting pop up menu 5 2 3 Geometry cards and Control cards menus These two menus provide a way of opening the card editor dialog panels of the various cards when working in PREFEKO mode Note that the cards are grouped by function ality The functionality is also available by clicking on the appropriate buttons in the button panel 5 2 4 Run menu This menu is used to launch the various FEKO components If another GUI component is started from the Run menu it automatically opens the same model Note however that CADFEKO does not automatically create a new model if
91. of triangular elements in m it is scaled by the SF card Maximum wire segment length Maximum segment length for wire segments in m it is scaled by the SF card Mazimum cuboid edge length Maximum edge length of cuboidal volume elements for di electrics volume equivalence principle of the MoM in m it is scaled by the SF card Maximum tetrahdral edge length Maximum edge length of tetrahedral volume elements FEM in m it is scaled by the SF card The IP card only affects the commands following it i e it has to be declared prior to the cards that define segments triangles or cuboids It is possible to use more than one IP card in a file This is necessary when a finer mesh is required in certain parts or when different radii occur in the geometry For any command e g the BL card the previous IP card is applicable Regarding the meshing certain rules apply relating the element size to the wavelength etc see section 2 2 2 for details EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 53 9 2 20 KA card With this card two points are joined which form the border of the PO area On this edge fringe wave currents are taken into account KA Define a PO region connection edge Start point of edge End point of edge Label of triangles on the PO border p Parameters Start point of edge Start point of the edge End point of edge End point The di
92. position y position tt Zposition angle o Y angle lie New excitation replaces all previous excitations Additional excitation is added to previous excitations Use the model of an electric ring current for the magnetic dipole the moment m uI A where I is the loop current and A the enclosed surface Use the model of a magnetic line current the moment m int where Im is magnetic line current and the length of the dipole The magnitude of the dipole For the electric ring current it is I Ain Am For the magnetic line current it is Im l in Vm Phase of the complex amplitude in degrees Coordinates of the position of the dipole in m These values are optionally scaled by the SF card The angle between the dipole and the z axis in degrees The angle between the projection of the dipole onto the plane z 0 and the x axis in degrees The power radiated by the dipole in a free space environment is given by Bo Zro IAL 127 P December 2005 FEKO User s Manual 10 19 10 20 DESCRIPTION OF THE CONTROL CARDS FEKO however considers the properties of the medium in which the dipole is located as well as the coupling of the dipole with surrounding structures or other sources for example other magnetic dipoles in an aperture approximation see the AP card when calculating the power radiated by the Hertzian dipole Even though the two formulations electric ring curre
93. present point It also deter mines whether and if so after how many iterations equal to the number of line searches plus one or the number of gradient calculations plus two the direction is periodically switched to EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 9 the steepest descent In the case of non harmonic functions this leads to better convergence while the quadratic convergence of harmonic functions is preserved provided that the restarts do not occur more often than every N iterations N being the number of variables to be optimised The following values are possible e 0 No new starts e 1 Restart after every N iterations e 2 Restart after every N 1 iterations e 3 Restart after every N 2 iterations Restarts after N 1 have proven to be reliable Restarts are registered in the log and or debug files in which the total number of line searches and gradient calculations is given sequentially The variant of Polak Ribiere does not allow any explicit restarts and this parameter must be initialised to 0 Delta for all variables DELTA establishes the dx for the calculation of the gradient single or double sided and allows a separate dx for every vari able according to the assumed sensitivity of the aim function for this variable The check box on the left can be checked if OPT FEKO should use the same value of Delta for all variables If a different val
94. previous excitations Propagation direction This determines if the spherical waves propagate Inward the model is illuminated with modes propagating towards r 0 i e spherical Hankel function of the first kind D gt or Outward the modes radiate towards r oo i e spherical Hankel function of the second kind 24 AD Traditional index smn If this option is checked the user can specify TE mode s 1 or TM mode s 2 and the indices m and n in the group below Here n is the mode index in radial direction and must be in the range 1 2 00 and m is the mode index in the azimuth direction y We do not distinguish between even and odd modes with cos my and sin my angular dependencies but rather use the angular dependency e Thus the index m can also be negative but it must be in the range n n December 2005 FEKO User s Manual 10 44 DESCRIPTION OF THE CONTROL CARDS Compressed index j With this option a compressed one dimensional mode numbering scheme is used The Mode index j is then specified in the field below Here j 2 n n 1 m 1 s where s 1 for TE modes and s 2 for TM modes This unified mode numbering scheme allows the computation of an extended scattering matrix with network and radiation ports This index j then represents a unique port number in the scattering matrix Magnitude of the mode in VW Absolute value of the complex amplitude of this specific spherical mode due to the appl
95. previously saved with the model then a basic template is loaded EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 49 Project name Creator Date created Date last edited Edited by Description Figure 4 24 The notes editor 4 18 Getting help Select Help gt CADFEKO manual to open the online documentation in the Help assis tant More information on how to use the Help assistant can be found from the Help assistant manual entry on the Contents tab of the assistant itself The Help assistant is automatically closed when CADFEKO is closed In addition pressing lt F1 gt in any dialog will open online help associated with that dialog The Help menu also gives access to the FEKO user manual and the Getting started manual These are PDF documents and the appropriate PDF viewer must be configured Select Options Preferences from the main menu and enter or browse for the path and name of a PDF viewer such as Acrobat reader Select Help About to show the version of CADFEKO 4 19 Short cut keys The following keyboard short cut keys are available in CADFEKO lt Shift gt lt F1 gt What s this extended tool tip help for the component that has focus lt F1 gt Context sensitive help for the dialog window that has focus lt F2 gt Rename selected item lt F9 gt Edit the workplane lt Del gt Delete selected items lt Shift gt lt Ins gt Paste clipboard text
96. ratio of 0 means that the wave is a linearly polarised wave but if the ratio has a value of 1 then it is a circularly polarised wave The direction of rotation is right hand circular RHC for 0 lt a lt 7 and left hand circular LHC for m lt a 8 lt 2r FEKO also computes and prints the polarisation angle y It is the angle between the major axis of the polarisation ellipse and the unit vector and can be computed using B cos 71 8 arctan _ 7 A cos Ti a If the FF card is used with NTHETA gt 2 and NPHI gt 2 the Poynting vector is integrated over the specified sector see the detailed discussion given with the FF card in section 10 2 28 The result is the radiated power and is given below the field values When analysing an antenna the source power calculated from the input impedance should equal the integral of the radiated power over the surface of a sphere This may be used as a partial validation of the result Note that power losses in dielectrics and finite conductivity should be taken into account separately The use may also elect to integrate the far field power without writing the field values to the output file using the FF card with FFREQ 3 FEKO then produces the output VALUES OF THE SCATTERED ELECTRIC FIELD STRENGTH IN THE FAR FIELD in V Factor e j BETA R R not considered Integration of the normal component of the Poynting vector in the angular EM Software amp Systems S A
97. relies on vertices of adjacent mesh elements being within a small tolerance of each other CADFEKO allows merging all vertices within a user specified tolerance To do this select one or more mesh parts and select Mesh Merge coinci dent vertices from the main menu to open the Merge coincident vertices dialog Here a Tolerance can be specified Any two points separated by less than this distance are then merged to the coordinates of one of the original vertices as opposed to taking the average position December 2005 FEKO User s Manual 4 42 WORKING IN CADFEKO If Snap to geometry points or Snap to named points is on mesh vertices lying within the specified tolerance of these points will be snapped to them For example if a named point lies between two mesh vertices that are less than the specified tolerance from each other they will be merged at this point Merging points can lead to degenerate collapsed triangles CADFEKO tries to avoid this by giving a warning if the tolerance is large relative to the mesh sizes It also automatically removes all degenerate elements after merging the vertices 4 13 5 Merging elements removing vertices The automatic mesh removal is meant primarily to merge vertices that should be the same but differ due to numeric tolerances If the points are further apart it may be required to control which point is moved and which point remains fixed It is also often required to remove specific eleme
98. required mesh sizes EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 37 X Create mesh 121xj m Mesh what All Selection Global mesh sizes Edge length 0 2 Segment length o 2 Wire segment radius 0 01 TF Enable volume meshing m Small features Defaut Optimise Ignore Small feature size jon Advanced IV Enable mesh smoothing Mesh size growth factor Slow e Fast Figure 4 19 The Create mesh dialog The mesh size is not allowed to be smaller than the maximum coordinate divided by 1 x 108 This is the limit of the numerical precision of the geometry For very small models requiring such small mesh sizes the geometry extents see section 4 6 1 should be decreased The mesh size is also not allowed to be larger than four times the extents The Small features group allows special treatment of small geometry details The Small feature size field specifies the limit of what is considered a small feature as a percentage of the part it belongs to The Default behaviour is to mesh these structures normally This will result in an accurate representation of the geometry potentially using very small elements Optimise is useful where the geometry has long narrow slivers or faces that are close together If this option is selected CADFEKO will try to align vertices on opposite sides of the small feature as shown in figure 4 20 Finally it is possi
99. s Manual 9 102 DESCRIPTION OF THE GEOMETRY CARDS Consider the structure shown in figure 9 43 consisting of four flat plates and a cylindrical section The two plates lying at 45 degrees to the coordinate system labelled 1 and 3 are half as wide as the plates with labels 0 and 2 Thus some triangles with label 2 are visible to some triangles with label 0 but not all Y Figure 9 43 Structure used to demonstrate the use of VS cards from demo VS1 pre We have to specify which triangles are visible hidden from all triangles with label 0 first then those visible from label 1 and so on The VS cards for this example would be as follows e Triangles labelled 0 are not visible from triangles with label 0 e Triangles labelled 0 are visible from triangles with label 1 e Triangles labelled 0 are not visible from triangles with labels 3 to 4 e Triangles labelled 1 are not visible from triangles with label 1 e Triangles labelled 1 are visible from triangles with label 2 e Triangles labelled 1 are not visible from triangles with labels 3 to 4 e Triangles labelled 2 are not visible from triangles with label 2 e Triangles labelled 2 are visible from triangles with label 3 e Triangles labelled 3 are not visible from triangles with label 3 e Triangles labelled 3 are visible from triangles with label 4 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 103 Since all the triangles
100. same graph On the 3D graph the Filename field applies to the entire display For the 2D graph it applies only to a single series Second POSTFEKO offers to update the data or make a copy of the values when the result BOF file changes See section 6 5 7 The control panel for a 2D graph has a graph settings toolbar on the left and a series control toolbar used to create delete and copy series of the specific data type on the graph at the top Each series has its own page area where the user selects which data to display Note that the associated BOF file is specified for each series The 2D graphs automatically display results in the appropriate units for example a plot between 2 x 101 and 2 x 1011 Hz is displayed between 200 and 400 GHz 6 5 1 2D result selection All 2D result pages contain the same selection group shown in figure 6 3 as the 3D result pages 2D results can however be plotted as a function of frequency solution number or EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 11 block number Hence multiple elements can be selected from all three lists but it is only possible to select multiple entries in one block at a time If any list has multiple entries selected it determines the independent plot variable If no list has multiple selected entries the independent variable defaults to a position variable If multiple entries are selected in any of the result lists the large
101. section 9 2 12 The excitations are described in detail in the following sections December 2005 FEKO User s Manual 10 8 DESCRIPTION OF THE CONTROL CARDS Al card Voltage source on a segment _ gt I T gt E 1 A2 card Voltage source on a node between segments gt E A3 card TEM frill on a segment py Magnetic current loop i ay Figure 10 1 Possible ways to realise a voltage source on a wire segment A4 card Vertical pin approximation dielectric substrate A7 card Voltage gap on an edge vyv v E i AE card Voltage gap along edges YYVVVVY Figure 10 2 Possible ways to realise a voltage source in connection with triangles EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 9 10 2 3 AO card This card realises excitation by a linearly polarised incident plane wave AO Specify plane wave incidence New source C Add to sources Polarisation C Left hand rotating elliptical Linear Right hand rotating elliptical Number of angles Number of angles Magnitude V m Phase degrees Initial value degrees Initial Y value degrees Polarisation angle degrees Incrementin degrees Incrementin degrees Ellipticity between 0 and 1 Parameters New source New excitation replaces all previous excitations
102. should be at least 1 5 times greater than with the normal calculation If there is a large difference in the results then an error has occurred e Doing a power balance The power fed into an antenna through the power source must be equal to the radiated power The radiated power can be calculated by integrating the power flux density This is done by using the FF command see example_07 or example_08 in the Examples Guide EM Software amp Systems S A Pty Ltd December 2005 THE LICENCE MANAGER 3 1 3 The licence manager The FEKO licence manager shows all the licences in the specified secfeko dat file for nodelocked licences or connects to the floating licence server and retrieves licence in formation from there This allows viewing the active components modules limits and expiry dates of all licences in a clear human readable form In addition for floating licences it allows viewing the available licences selecting which licence to use and managing the licences that are in use See also the section on floating licences in the Getting started manual in particular if you still need to set up the floating licence server The licence manager is started by typing secfeko_gui from a console window Under MS Windows it may also be started by selecting Licence manager from the FEKO menu under the Windows Start menu 3 1 Displaying licence information Figure 3 1 shows the licence manager with a typical node locked licen
103. similar to the field calculation in cylindrical coordinates around the z axis where the radius r changes with the height z and z lies within the range zo zo nz Az Observation Point ro Re z 20 cosp r ro amp z 20 sin Y z Unit vectors of the coordinate system cos Y sin p 0 r sin Y p cos Y t 0 0 1 Z A Z 234 x y Figure 10 22 Field calculation in the Conical coordinate system EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 79 10 2 28 FF card This card controls the calculation of the far fields in spherical coordinates FF Calculate the far fields Select field position No calculation Fields calculated as specified below Fields calculated only in incident direction Only integrate field over area given below J7 Calculate only the scattered part of the field Directivity Gain Number of points Number of points Initial CS Initial o 9 increment 2 increment y IV Compute spherical mode coefficients Maximum mode index N Parameters No calculation If this item is checked no calculation is done Fields calculated as specified below The far field is calculated with the specified settings Fields calculated only in the incident direction The far field is calculated only in the inci dent direction used for example to calculate monostatic RCS Only in
104. solids 4 18 surfaces 4 19 translate 4 24 validation 4 33 wires 4 21 geometry cards 2 1 9 1 9 3 BL 9 4 BP 9 6 BQ 9 8 BT 9 10 CB 9 12 CL 9 14 CN 9 16 DK 9 17 DP 9 19 DZ 9 20 EG 9 22 EL 9 25 FM 9 27 FO 9 28 FP 9 30 HE 9 31 IN 9 33 IP 9 52 KA 9 53 KK 9 54 KL 9 58 KR 9 59 KU 9 62 LA 9 64 ME 9 65 NU 9 68 PB 9 70 PH 9 72 PM 9 74 PO 9 76 PY 9 80 QT 9 81 QU 9 82 RM 9 84 SF 9 88 SY 9 90 TG 9 91 TO 9 94 TP 9 96 UT 9 98 UZ 9 100 VS 9 101 WG 9 104 ZY 9 105 geometry points imprinting 4 28 14 GF card 10 86 graph settings 6 13 graphics cards 4 1 Green s functions 10 86 showing 6 6 grid 4 6 ground plane 10 54 HE card 9 31 helices 4 21 helix 9 31 Hertzian electric dipole 10 18 hide single item 4 6 4 10 4 11 toolbar 4 3 hot keys CADFEKO 4 49 EDITFEKO 5 10 IF statement 7 9 images 6 16 impedance 10 99 loading 10 95 microstrip fed 10 95 impedance boundary condition 10 111 import geometry 4 22 4 31 9 33 graph data 6 15 meshes 4 39 9 33 impressed line current 10 23 10 29 10 49 imprinting points 4 28 IN card 9 33 incident plane wave 10 9 include files 9 33 independent variable 6 10 inductance loading 10 94 10 97 10 98 input file 2 1 intersect 4 26 IP card 9 52 KA card 9 53 Kardan angles 9 92 KK card 9 54 KL card 9 58 KR card 9 59 KU card 9 62 L4 card 10 92 LA card 9 64
105. symmetry The algorithm for this is that after having evaluated expressions or having replaced variables a label is split into the associated number and the remaining base string The associated number is split off from the back of the label and if there are no digits this is set to zero Examples December 2005 FEKO User s Manual 2 10 GENERAL COMMENTS Label name Base string Associated number 1 1 Roof Roof 0 Part_17 Part_ 17 When incrementing labels the base string is kept and the associated number is incre mented There is just one exception the label zero will always remain zero So for instance when incrementing labels by 2 we get this Label name Incremented label 1 3 Roof Roof Part_17 Part_19 When using ranges of labels then for the range specification to be valid the base strings must match and the associated number must be in the correct range between the asso ciated numbers of start and end label So for instance the label Part_12 is in the range of the labels Part_10 Part_20 but the label Part_5 is outside this range Using a range like Front Back is not valid different base strings 2 4 Utilisation of symmetry It is possible to reduce the calculation time and memory usage if symmetry is utilised This can be done by using the SY card section 9 2 37 Three coordinate planes x 0 yz plane y 0 xz plane and z 0 xy plan
106. that it is unusual to assign a value to nmat npuf The maximum number of control cards that may occur in a loop for example in a frequency sweep 2 7 Summary of the files The table below gives an overview of the different files and their respective functions STDOUT is the standard output usually the screen A is used to symbolically indicate the filename pre Filename Description STDOUT Usually the screen This is where comments such as progress warnings and errors are sent _14 Page temporary storage file for the matrix in the sequential version of FEKO with out of core solution _15 Page temporary storage file for the matrix in the sequential version of FEKO with out of core solution _16 Page temporary storage file for the matrix in the sequential version of FEKO with out of core solution _20 Page temporary storage file for the coupling coefficients of the MoM PO hybrid method during an out of core solution _21 Page temporary storage file for the coupling coefficients of the MoM PO hybrid method during an out of core solution afo Continuous frequency results created by ADAPTFEKO December 2005 FEKO User s Manual 2 20 GENERAL COMMENTS aus Output file of TIMEFEKO bof Binary version of the output file which is used for post processing cdb ANSYS mesh file which can be imported with the IN card cfm CADFEKO model file exported CADFEKO mesh to be imported by
107. the face borders a solid metal region or two free space regions the Metal surface property is ignored no special icon is shown If the property can be set the icon indicates if it is set to metal or dielectric If multiple surfaces are selected the Metal surface item is disabled if any of these surfaces cannot be set If all surfaces can be set but do not have the same state the Metal surface item is in a ternary i e not defined state This indicates that the existing states will be persisted and allows for example setting a local mesh size on a number of surfaces without changing their metal property Clicking on the checkbox cycles through checked unchecked and ternary The Mesh size field allows defining a local mesh size see section 4 12 1 4 9 Geometry validation CADFEKO provides tools to perform basic consistency checks on the geometry Since properly connected meshes are only guaranteed for single parts it is important to ensure that parts do not clash Parts clash if there is any contact between them or if one part is completely inside another Select all the items to test or press lt Ctrl gt lt A gt while selecting geometry parts and select Find Clashing geometry from the main menu The clashing parts remain selected and are listed in the message window The selection undo redo operations can of course be used to see what was selected before the operation December 2005 FEKO User s Manual 4 34 WORKING
108. the points required by the AP card in this part of the file December 2005 FEKO User s Manual 9 20 DESCRIPTION OF THE GEOMETRY CARDS 9 2 11 DZ card This card is used to create a cylindrical shell meshed into cuboidal elements for solutions using the volume equivalence principle in the MoM The meshing parameters as set at the IP card are used and the medium as set at the ME card is assigned to all created cuboidal elements DZ Specify a dielectric cylinder sf XS sa si lt saj om The angle Y degrees Po Maximum cuboid edge length on arc ss Choose the medium Dielectric C Magnetic C Both dielectric and magnetic FF Old format with medium parameters Parameters S1 S2 The start and end points respectively of the cylinder axis S3 S4 Points on the inside and outside respectively of the shell The angle vy The angle of the cylindrical segment in degrees Maximum cuboid edge length on arc Maximum edge length of the cuboids along the arc in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Choose the medium Select here whether the cylindrical shell is dielectric or magnetic or both this is always with respect to the environment e g if the relative permittivity r of the cuboid material differs from the environment then this is a dielectric cylinder Old format with medium parameters For a detailed desc
109. the A5 card The number of dipoles per line segment is specified with the parameter Number of dipoles per transmission line Note that this model is only valid if the line segments do not make electrical contact with any conducting 8To use this the CableMod PCBMod module must be activated if required please contact your distributor December 2005 FEKO User s Manual 10 24 DESCRIPTION OF THE CONTROL CARDS surface All the segments in the rsd file must be of the type intern and not loaded Model line with impressed line currents The line geometry frequency and currents are read from the rsd file and the line is modelled with a continuous current distribution using one AI card per line segment The AI cards are created automatically by PREFEKO when importing the rsd file If a line segment has a loaded endpoint it is auto matically modelled by an AV card to allow the electrical contact The radius of the impressed current element can be set in the pa rameter Radius of impressed current This parameter is optional and is passed on to the AI and AV cards See the description in these cards If the parameter is zero or empty a current filament approximation is used Source translation directions When importing transmission line currents from CableMod or PCB currents from PCBMod then the coordinate system of these programmes as represented in the rsd file is used and the source is imported at this position in FE
110. the appropriate button on the button panel or selecting from the Geometry cards and Control cards menus EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 7 The buttons are grouped according to functionality namely Definition of node points labels segmentation parameters and variables button Cards to generate surfaces which will be meshed into triangles elements Cards generating wire segments Cards for generating dielectric magnetic volumes to be subdivided into cuboids or specification of dielectric regions Cards used in connection with the PO formulation Cards to define the MLFMM and the FEM methods and parameters Cards used in connection with the UTD formulation Modifications to the geometry such as translation scaling and mirroring The EG card signifying the end of the geometry Generally the buttons above it should be used before the EG card and those bolow it should be after the EG card Exceptions are the DP and IN cards and the FOR NEXT and IF ELSE blocks Cards dealing with finite medium properties and finite grounds Cards dealing with loading of wire segments Non radiating networks Cards to specify the excitation type frequency and power of the excitation Cards used to control which data is written to the output files Cards to specify where to calculate the fields The EN card which signifies the end of the input file A typical card editor dialog is shown be
111. the current mesh to a CFM file which can then be imported in a PRE file The mesh is exported as is i e there are no checks to see if it is valid at this point If there are no mesh elements variables or named points in the model the CFM file will effectively be empty and importing it in a PRE file will have no effect This menu item only exports the mesh and neither the name nor the file itself is used again by CADFEKO When running components from the Run menu CADFEKO will automatically export a CFM file using the model name 43 The 3D view The 3D views are used to display and interact with the model CADFEKO distinguishes between a click operation mouse down and up at approximately the same location and click and drag the mouse is moved a minimum distance while the button remains down Clicking is used for selection see section 4 11 opening a context sensitive menu with operations for the current selection right mouse button and point entry left mouse button see section 4 6 3 The model is rotated by clicking and dragging the mouse It can also be zoomed by pressing lt Shift gt while clicking and dragging the mouse upward movement zooms in while downward movement zooms out horizontal movement is ignored Rolling the mouse wheel also zooms Pressing lt Shift gt while rolling the mouse wheel slows down zooming CADFEKO tries to zoom in out on the object below the mouse pointer hence rolling the mouse wheel while the cur
112. the element type and medium indices The ANSYS field for the material number cannot be used since for triangles FEKO requires two such material indices medium on each side EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 51 The user can also import points from the ANSYS CDB file similar to importing points from FEMAP or NASTRAN files The points defined in the ANSYS CDB file will then be available in PREFEKO as points as if they were defined by DP cards of the form Cxxx where xxx is the index of the grid point This may be used for example to attach additional structures to the geometry In addition the coordinate values of the points are available as variables in PREFEKO For example the variables c1234x c1234y and c1234z are set to the coordinates of the point with index 1234 Note that points are not included by default December 2005 FEKO User s Manual 9 52 DESCRIPTION OF THE GEOMETRY CARDS 9 2 19 IP card With this card a number of parameters that define the meshing parameters or also the wire radius are set IP Specify the segmentation parameters Radius of wire segment tid Maximum triangle edge lenath lt Maximum wire segment length Maximum cuboid edge length poo Maximum tetrahedral edge length Parameters Radius of wire segment Segment radius in m it is scaled by the SF card if used Maximum triangle edge length Maximum edge length
113. the first one only PREFEKO also allows the definition of variables see the next section from the command line for example calling PREFEKO with prefeko filename variableil valueil variable2 value2 sets the variables variable1 and variable2 such that it may be used in the pre file It is a good idea to use the print_to_out command to write these variables to the output file in order to keep a record of their values Note that in UNIX shells the character is a special character and needs to be escaped for example prefeko filename variablel value1l variable2 value2 December 2005 FEKO User s Manual 7 2 THE PREPROCESSOR PREFEKO 7 3 Symbolic variables Instead of using numerical values in all the different cards it is possible to use predefined variables The name of a variable always consists of a sign followed by a string consist ing of the characters a z A Z 0 9 and the special character _ The following are valid variable names height a STARTINGFREQUENCY a_1 or P5_7f while the following are not valid a 1 or value2 1 There is no distinction between upper and lower case characters For example a and A are interpreted as the same variable Expressions and functions may be used when defining variables so that direct calculations can be carried out The variables have to be defined before they can be used in the respective cards It is possible to use expressions like 2 radius in the in
114. the input admittance of a forked monopole For comparison we have plotted the input admittance scaled it to mSiemens and scaled the bottom axis to h A with h 1m Since we consider a dipole while their example uses a monopole we need to multiply the admittance with a further factor of 2 The result is shown in figure 13 4 and compares very well to the published result December 2005 FEKO User s Manual THE PROGRAM ADAPTFEKO 13 4 Re Z_in Im Z_in 4 r 4 EE EA EE A 4 P 4 2 500 2 000 275 300 250 225 Frequency MHz Figure 13 2 Input impedance of the forked dipole o wyo souepaduu 207 203 Frequency MHz Figure 13 3 Input impedance of the forked dipole around the resonance point The squares The marker at and circles represent values calculated at the discrete frequencies 206 2 MHz denotes the only adaptive sample point in this band December 2005 EM Software amp Systems S A Pty Ltd 13 5 THE PROGRAM ADAPTFEKO NN AN suaweaisul soueynupy 0 5 0 6 0 7 0 8 0 9 0 4 0 3 h lambda Figure 13 4 Input admittance of a forked monopole derived by multiplying the admittance of a forked dipole by a factor of 2 FEKO User s Manual December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 1 14 Description of the output file of FEKO The program
115. the more complex example of a dielectric cone medium 1 mounted on top of a metallic cylinder shown in figure 9 25 There are three types of triangles involved e Metallic triangles in free space Medium 0 on the bottom and side of the cylinder e Metallic triangles also forming the border surface of the dielectric body on the lid of the cylinder which is also the basis of the dielectric cone e Dielectric triangles forming the surface of the dielectric body the boundary between medium 1 the inner dielectric region and medium 0 the free space outer region on the top surface of the cone EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 67 Dielectric cone Medium 0 Metallic pa cylinder Figure 9 25 Example of a dielectric cone on top of a metallic cylinder to demonstrate the use of the ME card December 2005 FEKO User s Manual 9 68 DESCRIPTION OF THE GEOMETRY CARDS 9 2 27 NU card Surface triangles representing a NURBS surface are created using this card NU Specify a NURBS surface ja 3 Order p of Bezier curve in u direction la 3 Order q of Bezier curve in v direction Enterthe control points Rows correspond to the v direction Columns correspond to the u direction 1 2 3 4 5 afe fw fn Parameters Order p of Bezier curve in u direction The order of the B zier curve in the direct
116. the penalty function section the optimisation section and the aim function section each with a separate tab in the dialog panel If lt F1 gt is pressed in any of these sections the appropriate tab is opened If EDITFEKO cannot determine the section it opens the parameter tab The functioning of these options is discussed in Chapter 11 5 5 1 Parameter tab To add an optimisation parameter click the insert button to add a row into the parame ter table Similarly to delete a row click the delete button The number of parameters specified here determines the size of the Penalty function and Gain Optimisation tab tables To enforce the minimum and maximum boundaries check the Enforce min max boundaries checkbox The parameter tab also shows any errors in the structure of the OPT file in the Error box Double clicking on an error will highlight the error in the editor If the Include default comments is checked EDITFEKO will add the default comments before each section The user may also type additional comments in the text editor These comments will maintain their position also after editing the file in the dialog panel Note that the remaining tabs remain disabled until at least one variable is specified in the Parameter tab December 2005 FEKO User s Manual 5 10 THE EDITOR EDITFEKO 5 5 2 Penalty function tab To insert a penalty function check the checkbox The table shows all the parameters defined in
117. the power calculation in FEKO will fail S1 S2 and S3 These define the orientation of the aperture and should be clear from the figure on the dialog For a planar aperture it defines the position of the origin and the direction of the 2 and s directions respectively The field data is assumed to vary first along the z direction For cylindrical and spherical apertures they define the origin and the direction of the local z and x axes respectively All angles are relative to these axes see figures 10 11 and 10 12 E file name The input filename efe or text file from which the field data must be read H file name The input filename hfe or text file from which the field data must be read Start from point number The number of the first field point to be used for the aperture If set to 1 field values are read from the start of the file for larger values the first point number 1 values efe and hfe files or lines text files are ignored This may be used for example if the data file contains the field values for more than one aperture The Start from point number field is not used if the field data is obtained from the pre input file Number of points along These two fields specify the number of field points along each of the two axes of the aperture Amplitude scale factor A constant by which the amplitudes of all the dipoles in the aper ture are scaled Phase of aperture constant phase added to a
118. the relatively fast backward substitution has to be done December 2005 FEKO User s Manual 10 12 DESCRIPTION OF THE CONTROL CARDS 10 2 4 Al card With this card a voltage source is placed on a segment A1 Add a voltage source to a segment New source Add to sources Select segment Set source position Apply source to last segment with label Magnitude of source V fit Phase of source degrees A Segment centre S parameter impedance Ohm Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Select segment When this item is selected the Apply source to last segment with label field becomes active Here one specifies the label of the segment to which the source must be applied If more than one segment has this label the source is applied to the last segment with this label Alternatively one may select the item Set source position then the feed segment is determined by specifying the Cartesian coordinates in the Segment centre group These values are in m and are scaled by the SF card if Modify all dimension related values is checked Magnitude of source Magnitude of the voltage Uo in V Phase of source Phase of the voltage Uo in degrees S parameter impedance The port impedance if this excitation is used in connection with S parameter calculation If this field is emp
119. this information is not static as is the case with node locked licences With the exception of the machine code of each licence all the information displayed for node locked licences is also applicable for floating licences Here however a green line indicates a preferred licence see section 3 2 1 below and a light blue line indicates a licence that is in use For each licence that is in use the table displays the user and hostname where this licence is used and the Parallel column indicates how many parallel processes are available If a user has a 16 node licence he may start two 8 process parallel jobs but not an 8 process job and a 10 process job In addition expanding the licence shows information on when the licence was checked out and what components are in use If one checks in a licence see section 3 2 2 below which has just EDITFEKO checked out the user may be able to still save his work but if there is an instance of FEKO checked out it will be terminated EM Software amp Systems S A Pty Ltd December 2005 THE LICENCE MANAGER 3 3 A FEKO licence manager Ol x Info Server Help IV Default licence file J Local mode Servet icsry emss co 2a Update Preferred licence Clear JMFEKO icense secfeko dat Browse Port ieo fisi Floating licence no Used by Expiry date Suite Pricing category Memory limit Parallel a El Floating 2005 09 30 5 0 Platinum Unlimited H Initial checkout ast checkout hec
120. to generate elliptical cylinder with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases For an orthogonal cylinder i e the lines S1 S2 and S1 S3 are perpendicular the seg mented area shaded in the figure of the cylinder is obtained by rotating the point S3 around the axis S1 S2 through y For y 360 a full cylinder is obtained An oblique cylinder i e the circular or elliptical rim is not perpendicular to the axis can also be created Then S1 S2 still represents the axis but the top and bottom planes of the rims are defined by planes perpendicular to the plane defined by the three points S1 2 3 and parallel to the line S1 S3 December 2005 FEKO User s Manual 9 106 DESCRIPTION OF THE GEOMETRY CARDS Examples of ZY card usage The cylindrical section figure 9 45 elliptical cylinder figure 9 46 and non orthogonal cylinder figure 9 47 below were all created with ZY cards Figure 9 45 Example for the ZY card from demo_ZY1 pre Figure 9 46 Example of an elliptical cylinder from demo_ZY2 pre Figure 9 47 Example of a non orthogonal elliptical cylinder from demo_ZY3 pre EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 1 10 Description of the control cards 10 1 Overview of control cards and execution sequence The following table summarises
121. vertex selected the point is obtained from a point on the existing geometry or mesh Selecting Geometry face centre or Geometry edge centre snaps to the centre of gravity of the face edge under the cursor For curved edges the geometric centre does not necessarily lie on the edge When defining new geometry by snapping to existing geometry the current coordinates of the existing geometry are used There is no permanent relation and the new point is not updated when the existing geometry is changed The objects can be modified together if they are defined using named points see section 4 5 1 This is done by selecting Snap to Named point EM Software 4 Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 9 4 3 4 The 3D view toolbar Show hide Show hide OBAMA AA a LER A D Geometry Mesh Normals Global WWorkplane Transform Vertical Zoom to Undo Redo Selector axes grid workplane zaxis window view view Geometry Mesh Named Workplane Edit Specify Zoom ta Restore points vertices points workplane cutplanes extents default view The first nine toggle buttons on the toolbar at the top of the 3D view control the visi bility of objects Geometry solids surfaces and lines geometry points mesh elements mesh vertices mesh element normals named points the global axes the workplane and the grid can be shown or hidden with the respective toggle buttons If the button is toggled on
122. with range of labels layers Surface patches are converted to triangular elements nelude elements with tag Up to tag Scale factor For this option only the file name label selection and Include segments are supported The label selection uses the NEC tags which are converted to FEKO labels This applies to the tag when the element is defined If the tag is modified after the inclusion for example with the GM card the elements with the modified tag are also included The type selection parameter x is also supported but it may only have the value 1 for wire segments The NEC import filter considers only the geometry cards CM CE GA GW GM GR GS GX and GE A warning is given if other cards are encountered If the model contains multiple geometries only the first one is read 4G J Burke and A J Poggio Numerical Electromagnetics Code NEC Method of Moments Lawrence Livermore Laboratory January 1981 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 47 9 2 18 7 Import Concept geometry file With this option one may import CONCEPT geometry files IN Include an external file Import Concept geometry file y Include wire segments Include surface elements triangles and polygons File name FO El Scale factor Import wire segments and surface elements from Concept files separately Since CONCEPT uses two diffe
123. within the MoM FEM hybrid method these two techniques are fully coupled and also the surface of the FEM re gion is treated by the MoM For certain applications when there is a larger separation between the MoM and the FEM regions e g human body with a GSM base station antenna this decou pling checkbox can be checked Then similar to switching off the coupling for the MoM PO or MoM UTD hybrid methods first the MoM region is solved for by neglecting the FEM domain and this MoM solution is then used as impressed excitation for the FEM Also the MoM is in this de coupled case no longer used on the FEM surface but rather an absorbing boundary condition is applied there The advantage of this decoupling is a saving of memory and computation time Element order When second order is selected then FEKO uses hierarchal tetra hedral elements with LT QN linear tangential quadratic nor mal vector basis functions for the electric field inside the FEM region On the boundary surface of the FEM region CT LN con stant tangential linear normal vector basis functions are used for the equivalent electric and magnetic surface currents When first order is selected then CT LN basis functions are used every where on the boundary and inside When switching to first or der normally a finer mesh is required to get the same solution accuracy than second order Thus second order is the default However when having a fine mesh like modelling details of a
124. xk i e N 1 T f_max 34 FREQUENCY Upper frequency Number of Samples 250 0e 06 34 Normalise the time to that of the speed of light NORM Output the excitation EXCITATION The following is an extract from the output file cube aus TEMPORAL VARIATION OF EXCITATION NORMALISED TO U_O x y Zz 0 0 0 0 0 0 Time in lm Value 0 0000000e 000 2 31952283024e 016 3 0916097e 001 8 63275340216e 015 6 1832194e 001 2 65316865993e 013 9 2748292e 001 6 73356755347e 012 December 2005 FEKO User s Manual 12 12 THE PROGRAM TIMEFEKO V P BV HHH THETA PHI 90 00 0 00 Time in lm ETHETA EPHI 0 0000000e 000 2 98948137392e 005 0 00000000000e 000 3 0916097e 001 6 77873335003e 005 0 00000000000e 000 6 1832194e 001 4 51882462221e 005 0 00000000000e 000 9 2748292e 001 6 42849147499e 005 0 00000000000e 000 1 2366439e 000 6 07906709346e 005 0 00000000000e 000 1 5458049e 000 4 10609464655e 005 0 00000000000e 000 1 8549658e 000 1 46284430530e 004 0 00000000000e 000 2 1641268e 000 3 56160952549e 004 0 00000000000e 000 2 4732878e 000 1 37768474311e 003 0 00000000000e 000 2 7824487e 000 5 67653919004e 003 0 00000000000e 000 3 0916097e 000 1 78441744890e 002 0 00000000000e 000 3 4007707e 000 4 45400653850e 002 0 00000000000e 000 3 7099317e 000 8 92614320231e 002 0 00000000000e 000 4 0190926e 000 1 40179442097e 001 0 00000000000e 000 VALUES OF THE CURRENT DENSITY VECTOR ON TRIANGLES in A m no averaging number x m y m z m 1 5 00000E 01 5
125. z component of point P Points can be constructed with the pt command for example pt 1 1 1 Only the subtract and add operations are allowed between two points the corresponding components are added subtracted and a point may be multiplied with or divided by a scalar In addition the abs function listed above may be applied to points It gives the distance from the origin to the point i e the vector length if the point is interpreted as a vector Currently no other operations may be applied to points 4 5 2 Calculator Select View Calculator to open the Calculator which allows evaluating and testing variable and named point expressions without modifying any model entries The format of the result can be controlled Scientific uses exponential notation for example 0 01 becomes 1 0e 2 Engineering format is similar to Scientific except that the exponent part is always a multiple of 3 Thus 0 01 becomes 10 0e 3 Decimal uses a fixed notation without exponent This is not recommended for small numbers for example with 5 decimals 1 0e 6 becomes 0 00000 which means all information is lost The Decimals field gives the number of digits after the decimal point December 2005 FEKO User s Manual 4 16 WORKING IN CADFEKO 4 6 Creating geometry 4 6 1 Geometry extents Operations on geometry such as checking if two points are the same require a numeric tolerance This tolerance is dependent on the model size
126. zoom window The panel contents do not change when this button is pressed Zooming in does not reset the precision of the labels on the axis tick marks It may be necessary to increase the precision of the labels To do this use the axis settings panel 7 The Reset zoom button is only visible when zoomed in and restores the graph to the full dimensions of the axis specifications when pressed Note that the graph titles the axis captions and the series legends each use a check box Automatic update If this is checked POSTFEKO will attempt to use the correct text in the associated field This is determined from the selections on the control panel If the text field is changed this happens only when the field looses focus or the user presses lt Enter gt while typing in the field the update box is unchecked automatically While the box is unchecked the text is not updated If the selection is changed while this is the case the text field will be invalid until one checks the update box again or edits the text manually December 2005 FEKO User s Manual 6 14 WORKING IN POSTFEKO 6 5 6 Zooming rotating panning the model The user is often interested in inspecting details like close to resonances of the 2D graph Thus POSTFEKO allows zooming in on a specific part of the graph Note that zooming is not supported for polar plots or Smith charts To zoom in to an area click the Zoom box button on the left of the control panel
127. 0 9 4750E 01 6 0750E 01 2 7700E 02 Here each segment is assigned a consecutive number In the second column the label of the segment appears and below it the number of the medium in which it finds itself A zero 0 means free space vacuum Then the coordinates of the begin and end points of the segment follow In the previous row the numbers of the nodes that are adjacent appear A positive sign for the node number indicates that the positive current direction is defined away from the segment When there is a negative number then the positive direction is towards the segment In the next row the length of the segment appears followed by the radius December 2005 FEKO User s Manual 14 4 DESCRIPTION OF THE OUTPUT FILE OF FEKO For the data of the nodes between the segments a data table is given DATA OF THE NODES BETWEEN THE SEGMENTS no of segment points of segm No ISEGP ISEGM KNOP KNOM 1 1 2 2 1 2 2 3 2 1 3 3 4 2 1 info of symmetry yz XZ xy status 0 0 5 unknown 0 0 6 unknown 0 0 7 unknown The consecutive numbers of nodes are given in the first column Then the number ISEGP and ISEGM of the two connected segments follow A positive current direction is defined from the segment ISEGP to the segment ISEGM The column KNOP indicates whether the begin point KNOP 1 of the segment ISEGP connects to the node or if it is the end point KNOP 2 The following four columns contain the data about the symmetry and are the same a
128. 0 69 6 73 S 3 3 3 49405E 01 4 49374E 02 3 52282E 01 9 06 7 33 14 8 Computation time and peak memory The final section in the output file gives an overview of the computation in seconds time in a tabular format Reading Checking the geometry Initialisation of the Greens function Calcul Calcul Calcul Solution of the linear set of eqns Determination of surface currents Calcul Calcul Calcul Calcul SUMMARY OF REQUIRED TIMES IN CPU and constructing the geometry O of coupling for PO Fock of matrix A of vector Y right side of losses of electric near field of magnetic near field of far field ooo 00 00 0 00 090 other total times O SECONDS time runtime 031 0 031 000 0 000 000 0 000 000 0 000 031 0 031 000 0 000 016 0 016 000 0 000 000 0 000 000 0 000 000 0 000 031 0 031 000 0 000 109 0 109 This table is followed by an output of the peak memory main memory excluding possible out of core files usage which FEKO encountered during any solution phase Peak memory usage during the whole solution 41 275 MByte EM Software amp Systems S A Pty Ltd December 2005 COPYRIGHT NOTICES AND ACKNOWLEDGEMENTS 15 1 15 Copyright notices and acknowledgements The copyright for FEKO lies with Copyright 1998 2005 EM Software amp Systems S A Pty Ltd However FEKO uses also third party libraries and components both commercial and freely available one
129. 1 December 2005 FEKO User s Manual 10 88 DESCRIPTION OF THE CONTROL CARDS 10 2 30 2 Layered dielectric sphere GF Specify Green s functions Homogeneous medium Layered dielectric sphere C Planar multilayer substrate FF Allow metal structures inside sphere IV Use interpolation Single dielectric sphere y Radius Convergence criterion When this Green s function is selected the EM interaction of a layered dielectric sphere located at the coordinate system centre is taken into account With this option it is for example possible to analyse a cellphone in front of a spherical shell model of the human head very efficiently Parameters Configuration list The drop down list allows selecting between Single dielectric sphere and a core with a number of layers Note that whether metal structures are allowed influences the number of layers that are allowed Allow metal structures inside sphere When this item is checked metallic structures can be Use interpolation Convergence criterion Radius Er present in the inner parts of the sphere When this item is checked interpolation gfe and gfh files is used to accelerate the computations Convergence criteria for the summation of the rows of Green s functions If this field is O or undefined a sensible standard cri terion is used Radius of the sphere layer in m is scaled by the SF card For
130. 2 LOCAL coordinates s s ossa ii e a OR a e t 4 16 4 6 3 POM ity A A 4 17 EM Software amp Systems S A Pty Ltd December 2005 CONTENTS 111 4 6 4 Creating solid primitives 4 18 4 6 5 Creating surface primitives 4 19 4 6 6 Creating curve primitives o s e e ewoo a ur es 4 21 4 6 7 Importing exporting geometry 4 21 4 7 Operations on geometry o i eaa ees 4 23 4 7 1 Transformations lt ee pdi ee tia 4 24 4 7 2 Multiple transformed copies gt oa oo ecce gro venu uaa 4 24 4 7 3 Boolean operations o coco 4640 44444 25465 4 4 26 ATA SPE paS e d e eee hh aii iia a SBR AE es 4 26 47 5 Spinning and sweeping parts o 4 26 4 7 6 o A Ow ws we oes rs eh A i ead 4 27 4 7 7 Projection and imprinting points 4 28 4 7 8 Reversing face normals 4 29 4 7 9 Removing detail and the simplify operation 4 29 ALIO Wopy opiate awa awe CEE RY BEERS Se eS 4 30 AML Copy oignal cy ee ERS a a 4 31 47 12 Exploding parts gt ao ccs 6654 4 05452 eee dees 4 31 4 8 Specifying dielectric media 4 31 4 8 1 Metal ABE 2 bk Ae RA aR Rak a 4 33 4 9 Geometry validation sa a a aooe ee ee eee 4 33 410 Assemblies 62 0 00054 he See eed eee eee ceed 4 34 AJ Selecting WenS aca ea ee a bee eee eR 4 34 4 12 Creating meshes ee eee 4 36 4 12 1 Specifying mesh parameters 02 4 3
131. 333E 01 0 0000E 00 0 0000E 00 0 0000E 00 3 3333E 01 2 0 0000E 00 0 0000E 00 3 3333E 01 O 3 3333E 01 0 0000E 00 3 3333E 01 Cube 0 0000E 00 3 3333E 01 3 3333E 01 0 0000E 00 0 0000E 00 6 6667E 01 3 60 0000E 00 0 0000E 00 6 6667E 01 O 3 3333E 01 0 0000E 00 6 6667E 01 Each cuboid is given a consecutive number The x y and z corner points coordinates are given in the first three columns The first row is the reference point The second row is the corner point to which from the reference point the first basis function is defined Further the third and fourth rows define the next two basis functions with respect to the reference point In each dielectric cuboid there are three basis functions in each coordinate direction one The data of these basis functions is given in the following format DATA OF THE BASIS FUNCTIONS FOR DIELECTRIC CUBOIDS Symmetry information No cuboidno direc yz XZ xy status 1 1 1 28 55 109 unknown 2 2 1 29 56 110 unknown 3 3 1 30 57 111 unknown 4 4 1 31 58 112 unknown 5 5 1 32 59 113 unknown In the first column the consecutive number of the basis function is given The next column indicates the number of the cuboid The column direction indicates the direction of the basis function in the respective cuboid 1 indicates that e g the basis function is defined from the reference point to the second corner point The last four columns contain information concerning the symmetry properties of the cuboid where the s
132. 4 8 point names see nodes points geometry 4 9 imprinting 4 28 in PRE file 4 47 named 4 15 Polar plots 6 13 polarisation 6 16 polygons 4 19 9 80 definition 2 3 meshed 9 74 normals 4 44 UTD formulation 9 98 polyline 4 21 port 3 2 POSTFEKO 6 1 command line 6 1 control toolbar 6 2 graphs 6 1 help 6 18 load import data 6 15 loading sessions 6 1 overview 6 2 sessions 6 1 power input 10 105 PRE files 4 5 4 46 named points 4 47 variables 4 47 PREFEKO 7 1 preferences CADFEKO 4 46 EDITFEKO 5 5 preferred licence 3 3 PRINT command 7 11 priority setting 8 1 program execution control 10 103 project notes 4 48 projection 4 28 properties medium 4 31 mesh 4 38 4 45 modify 4 23 PS card 10 103 PW card 10 105 PY card 9 80 QT card 9 81 QU card 9 82 quadrangle 9 8 radiation patterns 10 79 patterns as sources 10 38 radius segments 4 36 4 38 raw data 6 15 series 6 12 6 14 real ground 10 54 10 86 redo model 4 4 selection 4 36 view operations 4 9 referencing elements 4 47 reflectors 4 19 regions 4 11 properties 4 31 4 38 remeshing 9 84 remote execution 5 4 remove duplicates 4 42 slivers 4 42 I 7 renaming geometry 4 23 mesh elements 4 41 rendering 4 1 options 4 6 requested field points 6 6 resistance loading 10 94 10 95 10 97 10 98 restore deleted faces edges 4 31 results checking validity 2 26 reuse objects
133. 6e 00 2266e 00 oooo ooqcooqcocoocooooqoqooqoqoqoo 0c 3 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 0000e 00 PRPRPRPRPRP RPP PREP RP pa pa pa pa pa plo pr pa pa opa ops 7 1202e 00 7 2145e 00 7 0740e 00 7 1914e 00 7 1658e 00 7 1970e 00 7 2171e 00 7 2225e 00 7 2218e 00 7 2150e 00 7 1728e 00 7 1769e 00 7 2205e 00 7 2053e 00 7 2270e 00 7 2282e 00 7 2214e 00 7 2218e 00 7 2255e 00 7 2207e 00 7 2281e 00 7 2268e 00 7 2266e 00 7 2266e 00 December 2005 FEKO User s Manual 11 30 THE OPTIMISER OPTFEKO 29 5 2910e 00 7 8014e 01 7 2274e 00 0 0000e 00 1 7 2274e 00 30 5 5822e 00 7 8376e 01 7 2262e 00 0 0000e 00 1 7 2262e 00 31 6 9210e 00 7 8159e 01 7 2283e 00 0 0000e 00 1 7 2283e 00 32 6 5232e 00 7 8292e 01 7 2279e 00 0 0000e 00 1 7 2279e 00 33 6 7754e 00 7 7978e 01 7 2279e 00 0 0000e 00 1 7 2279e 00 34 7 3187e 00 7 8027e 01 7 2277e 00 0 0000e 00 1 7 2277e 00 35 7 4643e 00 7 8208e 01 7 2281e 00 0 0000e 00 1 7 2281e 00 36 7 0666e 00 7 8341e 01 7 2279e 00 0 0000e 00 1 7 2279e 00 37 7 1927e 00 7 8184e 01 7 2282e 00 0 0000e 00 1 7 2282e 00 38 6 9938e 00 7 8250e 01 7 2282e 00 0 0000e 00 1 7 2282e 00 Optimisation finished standard dev small enough 5 7735e 05 Result destination
134. 8 412 3 Tanaris meshes so s d du es RR a E 4 39 4 13 Mesh validation and editing 4 40 ALL Mesh Mormaii a ENE a a a aa i e e 4 40 4 13 2 Relabelling mesh elements 4 41 4 133 Transforming mesh parts lt 4 41 December 2005 FEKO User s Manual iv CONTENTS 4 13 4 Merging coincident vertices 4 41 4 13 5 Merging elements removing vertices 4 42 4 13 6 Remove duplicate and collapsed elements 4 42 4 13 7 Finding distorted and oversized elements 4 43 4 13 8 View free mesh edges and segment nodes 4 43 4 13 9 Editing mesh vertices 4 44 4 13 10 Creating mesh triangles 4 8 888 2h eu ewe 4 44 4 13 11 Reversing normals 1 cee eee 4 44 4 13 12 Setting mesh properties 02 5 4 45 SUA a oe ew E E E ew oe We OE we 4 46 ALS Timing components 20 4 4 446 ee oe eee a ne eee ee eS 4 46 415 0 Solution Options sa esse bbb eee eee ee de 4 46 4 16 Working with CADFEKO models in EDITFEKO 4 46 ANG etme WS s aba es ee EER OE RS SEES 4 47 4 16 2 Referencing elements o 4 47 4 16 3 Using variables and named points in EDITFEKO 4 47 4 16 4 Setting dielectric parameters 4 47 4 16 5 Unsine symmetry 2 2 4 sa ver ra ee ee 4 48 LIT Notes editor s o e uosa ea m aada aa ee ea a kk ee a 4 48 AIN etme holp o o ke a
135. 9 9999 7 1166 POLARISATION axial r angle direction 0 0000 0 0000 0 0000 180 00 LINEAR 180 00 LINEAR 180 00 LINEAR 0 00 dB larger than directivity The directivity gain is based on an active power of 4 88015E 03 W and on a power loss of 0 00000E 00 W For incident plane waves the values that are displayed here are the values of the scattered field i e the incident field is not taken into account However for any other sources e g elementary Hertzian dipoles or impressed radiation pattern or transmission line the fields radiated by the excitation are considered December 2005 FEKO User s Manual 14 12 DESCRIPTION OF THE OUTPUT FILE OF FEKO In the far field a complex field strength Etar is defined using the relation eTiboR far a with a large distance R r which tends to infinity and which in the FEKO calculations is identical to infinity Please note that the dimension of Efay is voltage due to this extra distance factor R In the out file the J vertical and y horizontal components of Ej are tabulated by magnitude and phase i e Etar and Efar With POSTFEKO also results for other polarisations can be extracted The corresponding formulas used are then gt 1 gt gt Ears TR Eiis Baro V2 for S polarisation 4 l s P Etar z Y Biro aro for Z polarisation a i fx a Etar LHC Bore jEtar o bo for left hand cirular polarisation and 5 la pe Etr RHC
136. AYER_ convert to label nelude structures with layer e Up to layer PEE Scale factor OoOO In addition to the file name label selection and scale factor discussed in the general section of the IN card above the DXF import option supports the following element selection Include segments Same as above Include meshed polylines triangles and quadrangles Check this item to include meshed polylines triangles and quadrangles from the DXF file into the model Include node points Check this item to include node points from the DXF file into the model Include closed polylines meshed into triangles Check this item to include closed polylines from the DXF file into the model These structures will be meshed by PREFEKO Layers named n or LAYER_n where n is an integer number in the dxf model are converted to label n in FEKO For all structures for which no label is defined in this format the label specified with the last LA card preceding the IN card is used If no such LA card is in effect the default is label 0 This label is used in the label selection As for the other meshed CAD formats dielectric triangles or metallic triangles which form the surface of a dielectric are created by preceding the IN card with the appropriate ME card PREFEKO only processes the geometry information in the section of the file between the keywords ENTITIES and ENDSEC EM Software amp Systems S A Pty Ltd December 2005
137. Add to sources Additional excitation is added to previous excitations Polarisation This group sets the behaviour of the polarisation vector If either of the rotating options is selected the Ellipticity must be specified below Number of Y angles If more than one direction of incidence is to be examined then this parameter indicates the number of incident angles in the Y direction If this field is left empty or set to 0 a value of 1 will be used Number of p angles If more than one direction of incidence is to be examined then this parameter indicates the number of incident angles in the p direction If this field is left empty or set to 0 a value of 1 will be used Magnitude Magnitude of the field strength Eo of the incident field in Y Phase Phase of the field strength Eo of the incident field in degrees Initial Y value Angle of incidence Y of the plane wave in degrees see the figure in the card above December 2005 FEKO User s Manual 10 10 DESCRIPTION OF THE CONTROL CARDS Initial p value Angle of incidence y of the plane wave in degrees see the figure in the card above Polarisation angle 1 See the figure in the card above It is the angle in a right handed sense when viewing in the incident direction from 4 to Eo Increment in Y If more than one direction of incidence is to be examined Y is incremented by this value for each new angle of incidence Increment in p If more than one dire
138. Booleans transforms splitting etc are applied to the individual items If multi parent operations are applied to items in one assembly the result is also in that assembly Where such operations are applied to items from more than one assembly the result is placed at the root level Assembly names are part of the full label name for example Assembly1 Union4 Face12 This is the reference required in EDITFEKO to refer to elements on this specific face Note that all names in CADFEKO are case insensitive i e Facel and facel are the same 4 11 Selecting items Items are selected by clicking either in the tree or in any 3D view Selected items are highlighted in the tree and all 3D views When parent objects are selected in the tree CADFEKO draws wire frame outlines of these objects in the 3D view These items are not themselves part of the model but it is very useful to be able to distinguish the different parents If the current dialog operates on items that are no longer selected these items are shown on a green background in the tree EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 35 Pressing lt Ctrl gt while selecting items in the tree or a 3D view will add them to the current selection or remove them if they are selected Pressing lt Shift gt while clicking on items in the tree will select everything of the same type from the first item of the current selection Since the order of items
139. CRIPTION OF THE GEOMETRY CARDS 9 49 9 2 18 10 Import PATRAN neutral file PREFEKO also supports importing PATRAN files IN Include an external file Import PATRAN neutral file y Y Include segments Y Include quadrangles Y Include triangles FF Include node points F Include only node points for imported triangles and or wires File name PC Fl Include all items C Include only items with single label layer C Include items with range of labels layers PATRAN properties convert to FEKO labels nclude structures with property Up to property Scale factor PATRAN does not support polygonal plates but all other parameters in the general section of the IN card above apply The label selection uses the PATRAN material ID s which are converted to FEKO labels Only the following PATRAN neutral packet types are imported 01 Node data all coordinates are interpreted in the global rectangular frame local coordinate frames are not supported 02 Element data The shapes 2 bar 3 tri 4 quad and 5 tet are allowed Quadrangles are automatically subdivided into triangles along the shortest diagonal 99 End of file flag Other packet types are ignored As when importing neu files the wire radius must be set with the IP card preceding the IN card and an ME card must be used when specifying dielectric surfaces in the same way as when the IN card is not present The user can also
140. DESCRIPTION OF THE CONTROL CARDS 10 2 15 AR card With this card the radiation pattern of an antenna is used as an impressed source The pattern is read from a data file or defined in the pre file below the AR card This card has a variety of uses for example importing measured radiation patterns synthesising arrays from the individual patterns of the elements realising radiation only within certain sectors etc In the MoM UTD hybrid it is possible to simulate for exam ple the antenna on its own and to save the far field in a ffe file This field is then imported and used as source in the UTD part which may greatly speed up the ray tracing computation as there is now only one source point AR Point source with specified pattern New source Add to sources Read pattern data from a ffe file an external data file after this line in the pre file Source amplitude scale factor Pp Phase of source degrees J Source position coordinate Rotation about the axes Start from point number pp No of points No of P points Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Read pattern data from In this group the user must select one of three options e a ffe file Read the radiation pattern from an ffe format file which may be crea
141. DESCRIPTION OF THE OUTPUT FILE OF FEKO After the calculation of the currents the losses that result from finite conductivity are displayed POWER LOSS in Watts in the segments Label skineffect ohm loss distr load 2 0 0000E 00 0 0000E 00 0 0000E 00 totall 0 0000E 00 0 0000E 00 0 0000E 00 Total loss in the segments Total loss in the triangl Loss total i Efficiency of the ant coating 0 0000E 00 0 0000E 00 0 0000E 00 5 6359E 07 5 6359E 07 in the triangles skineffect ohm loss 5 4620E 07 1 7386E 08 5 4620E 07 1 7386E 08 W W W 99 9877 Y In the first column the label is displayed the lowest row displays the sum 14 5 Near fields If the near field is calculated the following data is displayed VALUES OF THE ELECTRIC FIELD STRENGTH in V m total field incident and scattered LOCATION medium X m Y m Z m O 0 00000E 00 0 00000E 00 1 00000E 00 O 1 00000E 01 0 00000E 00 1 00000E 00 O 2 00000E 01 0 00000E 00 1 00000E 00 O 3 00000E 01 0 00000E 00 1 00000E 00 EX magn 6 70088E 01 6 46235E 01 6 23014E 01 5 99908E 01 EY phase magn phase 99 86 7 65636E 01 166 42 74 23 1 14589E 00 166 13 47 98 1 55289E 00 165 83 21 51 1 95743E 00 163 95 EZ magn phase 6 89061E 01 126 74 7 17685E 01 98 76 7 35678E 01 70 70 7 41473E 01 42 30 Displayed are the position as well as the individual components of the electric and the magnetic field strength This is if not reques
142. EKO 11 7 Deviation termination Reflection Contraction Expansion If the standard deviation of the aim function at the nodes of the simplex is less than this value the optimisation will terminate This value determines the scale factor that will be applied to every reflection operation This value determines the scale factor that will be applied to each contraction operation This value determines the scale factor that will be applied to each expansion operation The keyword SIMPLEX_METHOD or SIMPLEXVERFAHREN is added to the opt file to use this optimisation function Conjugate gradient method This optimisation method calculates the gradient of the aim function at each evaluation point Based on the gradient at this point as well as the gradient at previous points a new search direction is chosen A line search finds the minimum of the aim function in this direction The next point for the optimisation function is at this point The new search direction can be calculated using one of two methods in FEKO The first is the Fletcher Reeves algorithm and the second is the variation by Polak Ribiere In general the Polak Ribiere variation is preferred since it allows restarting One two sided gradient F Optimisation Optimisation type Cojugate gradient y Oneltwo sided gradient Po Termination FTOL oes Termination GTOL oea Search step length LAMBDA 1 0E 3 00000 Interval GOLD herso ooo Extrap
143. EKO 13 1 Description In examples with narrow resonances a fine frequency resolution is required to locate these resonances If the frequency band is large a very large number of analysis may be required if simple linear or multiplicative frequency stepping is used ADAPTFEKO is used to overcome these problems It uses an adaptive frequency sampling and interpolation automatically using smaller steps near resonances and larger steps where the results are relatively smooth For each frequency it creates a pre file and calls PREFEKO and FEKO The file names are derived from the original name plus _ada_ plus a numerical value for exam ple the new files associated with forked_dipole pre are forked_dipole_ada_1 pre forked_dipole_ada_2 pre 13 2 Running ADAPTFEKO ADAPTFEKO is started automatically by RUNFEKO if the FR card contains the flag for adaptive frequency sampling see sections 8 2 and 10 2 29 The syntax is runfeko filename runfeko filename adaptfeko options options where the optional argument options in the second line may be keep files All solution files pre fek out etc are preserved restart x Restart an adaptive frequency analysis using results for the frequency points 1 x 1 obtained in a previous run Then the previous run must have used keepfiles 13 3 The pre input file The pre file is created as for linear or multiplicative stepping The only requirement is that only one FR card
144. EKO 7 3 SIN COS TAN COT ARCSIN ARCCOS ARCTAN ATAN2 ARCCOT SINH COSH TANH SQRT LOG EN EXP BESJ n x BESY n x BESI n x BESK n x ABS DEG RAD STEP CEIL FLOOR MAX MIN FMOD multiplication division powers for example 273 8 sine argument in radians cosine argument in radians tangent argument in radians cotangent argument in radians arcsine in radians arccosine in radians arctangent in radians this function has two arguments atan2 Hty tx it yields arctan y x in the range 7 7 arccotangent hyperbolic sine hyperbolic cosine hyperbolic tangent square root logarithm to the base 10 natural logarithm exponential function Bessel function J a of integer order n gt 0 and real argument x Neumann function Y 1 of integer order n gt 0 and real argument x Modified Bessel function of the first kind Jn x of integer order n gt 0 and real argument x Modified Bessel function of the second kind K of integer order n gt 0 and real argument x absolute value convert radians into degrees convert degrees into radians step function i e STEP x 0 for lt 0 STEP z 1 for gt 0 smallest integer value that is equal to or greater than the argument largest integer value that is equal to or smaller than the argument returns the largest of the two arguments called as max a b returns the smallest of the two arguments called as min a b this function also ha
145. EKO User s Manual 10 102 DESCRIPTION OF THE CONTROL CARDS off the averaging that may be very time consuming particularly for structures containing a large number of triangles is switched off Multiple OS cards can be used to extract currents on multiple non consecutive labels The options where a rsd file is written permit the creation of a rsd file for use with the transmission line simulation program CableMod or the PCB tool PCBMod The currents along all or selected segments are exported to the rsd file the filename without extension is the same as that of the fek file The rsd file is an ASCII file and contains first a description of the geometry of the line followed by blocks with the current information for each frequency It can be read by CableMod or PCBMod and can also be imported back into FEKO to realise an impressed line source see the AC card If the current of dielectric triangles surface current formulation must be output by the OS card both the equivalent electric and magnetic surface currents of the external problem are written to the output file The currents of the internal problem are different to those of the external problem only in that their sign is reversed If requested by the DA card a os card will be created in addition to the currents written to the output file 10T gt use the CableMod PCBMod interface this module must be activated if required please contact your distrib
146. EKO may fail for such cases Examples of PH card usage The PH card can be used to create the rectangular plate shown in figure 9 30 Note the extremely narrow triangles at the corners as mentioned above Figures 9 31 and 9 32 show respectively a quadrangular and a rectangular plate with the same elliptical hole The triangular plate is obtained by leaving the field S3 empty EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 73 Figure 9 30 Example using the PH card from demo_PH1 pre C Figure 9 31 Example of a quadrangular plate with an elliptical hole demo PH2 pre Figure 9 32 Example of a triangular plate with an elliptical hole demo_PH3 pre December 2005 FEKO User s Manual 9 74 DESCRIPTION OF THE GEOMETRY CARDS 9 2 30 PM card A surface mesh of triangles in the shape of a polygon is created by using this card This card also allows the specification of interior mesh points This card should generally be used in favour of other cards that create flat surface meshes with straight edges Parameters Specify non uniform Specify internal points Corner points Internal points Edge length PM Polygon to mesh into triangles a a IV Specify non uniform meshing IV Specify internal points E D Corner points Internal points Edge length a A B B C C DA D E E F F G G H A H 1 l J 8 J KA K L amp L MA v M A
147. ESCRIPTION OF THE CONTROL CARDS 10 23 10 2 11 AC card This card inputs data from a rsd file containing the geometry of a transmission line or PCB structure and the current distribution along this line or on the PCB for one or more frequencies Such a rsd file is created for example by the transmission line simulation program CableMod or by the PCB code PCBMod or by a current export with the OS card in FEKO The excitation is due to the electromagnetic fields radiated by these line currents the CM card allows the treatment of electromagnetic fields coupling into lines AC CableMod excitation New source C Add to sources No action use as loop termination C Model transmission line with Hertzian dipoles Radius ofimpressed current Source translation directions Rotation about the axes zz File name El IV Use adaptive frequency sampling Maximum number of discrete frequency points Minimum frequency stepping Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations No action No execution do not read the rsd file this option is used to specify the end of the frequency loop see below Model transmission line with Hertzian dipoles The line geometry frequency and currents are read from the rsd file and the line is modelled with an array of Hertzian dipoles see
148. FEKO User s Manual Suite 5 1 December 2005 Copyright 1998 2005 EM Software amp Systems S A Pty Ltd 32 Techno Avenue Technopark Stellenbosch 7600 South Africa M Tel 27 21 880 1880 Fax 27 21 880 1936 D E Mail feko emss co za GENS WWW http www feko info CONTENTS i Contents 1 Introduction 1 1 11 FEKO Oyeiview 24 e554 tee a Senne oS ee eS 1 1 1 2 Contacting your distributor or EMSS 1 3 2 General comments 2 1 21 Obreehibe Gi the mpi Mle rr 244 oe Seren gs HESS Ee HS 2 1 2 2 Modelling and meshing guidelines 2 2 2 2 1 Definitions and terms ss ce eeose s saama nae 2 2 2 4 2 Meshing guidelines regarding element sizes 2 3 Bedd Meshing guidelines regarding connectivity 2 5 2 3 Usage and concept of labels caca o 2 8 am Utilisation ol symmetiy a sai dad ea a Ra a i E 2 10 2 4 1 Geometric ENTE e a a N 2 10 2 4 2 Electric symmetry 4 4408 ee eee aD eR AR ES 2 11 2 4 3 ao 1 II 2 11 2 4 4 Example of the application of symmetry 2 12 2 4 5 Special enforcement of symmetry Even odd method 2 13 25 Dielectric solida ye fae Ee eh Be i ee eB AA 2 14 2 6 Dynamic memory management 2 16 2 6 1 Telling FEKO how much memory can be used 2 16 2 6 2 Other variables that are under user control 2 17 2 6 3 Variables that are automatically set correctly 2 17 Zo Bummery
149. IF ELSE ENDIF constructs 20004 TO Symbelio toda AMES ss saa oe ew a a a e e i it PRINT and EXIT command coccion mood 8 The FEKO solution kernel Beek Tye II 582 Rumning the FEKO kernel i eaaa ee ee bw bee NA 8 2 1 8 2 2 Aide Running the sequential version Running the parallel version o Running on a remote host s sas cca aama saanet eu 6 11 6 11 6 12 6 13 6 14 6 14 6 15 6 15 6 16 6 16 6 17 6 17 6 17 6 18 7 1 7 1 7 1 7 2 7 7 7 9 7 10 8 1 8 1 8 1 8 1 8 2 8 5 EM Software amp Systems S A Pty Ltd December 2005 CONTENTS vil 9 Description of the geometry cards 9 1 9 1 Overview of the geometry cards o 9 1 9 2 Alphabetical description of the geometry cards 9 3 9 2 1 PE Card o a a ee a Ree Sa a we a eh de a 9 3 Baa eed ew se a ee ed A Se Gee eS 9 4 9 2 3 Brogan EIA 9 6 9 2 4 Boae eea PAGE a ee ye eo Bae ee SG ee 9 8 O25 beets onc btiy bee be eee e bh eas amp 4 9 10 9 2 6 A AS Did alec ng we a Gs hy Spe Sosa 9 12 Wie RR A ke ee ee e e E 9 14 9 2 8 o oe ae be dk Be Ss eres ayo hos 9 16 S20 OR eee AMI ew ae Ee NN 9 17 Ol DOS 6 one oh AOS Se ear ey REDS Ae A wo 9 19 O Wye he s aiaa ae Go ek ie Ge Ue te Uy oe Se 9 20 Oke EGUAN 6 oe eG DS SS we ee R amp S eee 9 22 le ELGA cosa ara A PS BS Lhe he 9 25 Gala PM Card ia a ee Dae eee bee SARS 9 27 S215 FO cht oe cerana oa Ye hE ADEE Le
150. ITFEKO was designed to simplify the process of generating PRE files It is a basic text editor with customised functionality The interface consists of an editor area where more than one file may be opened each in its own edit window The toolbars at the top provides quick access to some standard functions The status bar on the bottom of the window contains license information indicates when Overwrite is on the line and column numbers and also gives an indi cation of the file modification status In the standard PREFEKO mode the button panel provides quick access to the card editor dialogs 4 EDITFEKO File Edit GeornetryCards Control Cards Run Windows Help Ca a GRS IAS ABRAS SMSs Points Labels or La cB IP Rm Segmentation Surface triangles BP BQ BT EL KK KR A example pre PREFEKO input file generated by CADFEKO Wire segments BL c HE wo pie Inport Ea ofn Dielectrics ME bk DZ l QU l QT End of geometry 0 Fo ka KL Po vs EG 1 FM x Set frequency 1 El py ur uz FR Set source x Solution control Modify geometry sy sF 16 TP on IN End of geometry EG Loops and tests print exit if else andii for next Dielectrics Bo sk oF DI co Impedance load LD LE LP Ls Lz La Miscellaneous TE co CF su Excitations AD Al A2 A3 A4 AS gt x End of file EN CableMod INS Line 1 Column 1
151. If this parameter is left empty the value specified with the IP card is used A complete sphere may be created with Va Ya 0 Ve 180 and ye 360 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS An example of KU card usage The spherical segment shown in figure 9 24 is generated using the KU card SGU De Figure 9 24 Example for the KU card from demo_KU1 pre December 2005 FEKO User s Manua 9 64 DESCRIPTION OF THE GEOMETRY CARDS 9 2 25 LA card With this card labels are assigned to segments triangles polygons cuboids UTD cylin ders and points LA Assign labels Label for following geometry Parameters Label for following The label assigned to all segments triangles etc defined in cards following this one In order to select the position of the feed Ax cards the location of impedance loading LD LS LP and LZ cards or structures on which to apply the skin effect SK cards each segment triangle etc is assigned a label Other applications include the selective transformation or copying of parts of geometry TG card and outputting of currents on selected elements OS card Labels are also used to define triangles on which to apply physical optics PO card All elements etc that are created after the LA card e g by a BP card are assigned the value specified in the dialog as label A different label is only
152. KO Here an offset can be specified which translates the source in x y or z direction Standard FEKO units are used for these offsets i e metres but scaled accordingly if a factor is set at the SF card Note that the units as specified in the rsd file are not applicable here for the translation parameters only to the import of the data Rotation about axes Like the translation described above an imported source can here be rotated and thus positioned arbitrarily The rotation angles are in degree and the same definition as also used at the AR or TG cards applies see section 9 2 38 for details File name The name of the rsd file Use adaptive frequency sampling Only read the minimum and maximum frequency from the rsd file and obtain a continuous solution in this frequency band using adaptive frequency sampling If this option is used only one AC card is permitted in the pre file and no FR cards Maximum number of discrete frequency points When using adaptive frequency sampling the maximum number of sample points can be specified here See also the discussion on adaptive frequency sampling at the FR card Minimum frequency stepping When using adaptive frequency sampling it could be neces sary to specify the minimum allowable frequency between sam ples See also the discussion on adaptive frequency sampling at the FR card If the imported rsd file contains currents for several frequencies the option New source
153. KO_TMPDIR FEKO_USER_HOME This directory is used to write user specific initialisation files This variable replaced FEKO_WRITE It is provided to allow different users to save unique configurations or for when the user does not have write access to the FEKO di rectory For Windows systems this is normally the same as FEKO and on UNIX systems it is usually set to HOME feko during the installation EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 25 FEKO_WHICH MPI FEKO uses different MPI implementations for the different platforms and thus the different platforms require different command syntax to start FEKO RUNFEKO provides an interface that remains the same on all platforms However it must know which MPI implementation is used This is done by setting the environment variable FEKO_WHICH_MPI it is automatically set by the installation script to one of the following options Not initialised MPICH for example Linux or SUN HP MPI NEC MPI SGI MPI CRAY SGI MPI on CRAY T3E ScaMPI on Linux 1432 AMD64 EM64T Compaq MPI on Tru64 UNIX SCore on Linux Myrinet clusters GM on Linux Myrinet clusters Parastation MPI on Linux 1A32 FEKO_WRITE_RHS If this environment variable is set value arbitrary FEKO writes the right side of the set of linear equations to a rhs file This is only useful for test purposes such as when one wants to analyse this vector with another program OemaonNnnanrw
154. Label visibility visible horn Face39 horn Face40 horn Face41 horn Face42 horn Face44 horn Face45 horn Face46 horn Face48 horn Face49 Figure 6 2 The model view control panel horn Wire109 Medium visibility EM visibility Hidden The 3D display options applies to one model at a time This model is selected from the list of loaded FEK files with the Current file field at the top of the panel If the model file is changed all selected settings are applied to the new model if possible The check boxes at the top of the page facilitates displaying specific objects and types of items In addition moving an item from the Visible list to the Hidden list at the the bottom of the page hides all items with that label medium EM properties Changing the Geometry colour group facilitates using colour to identify labels media the element type metallic dielectric triangles segments tetrahedra etc and the applied December 2005 FEKO User s Manual 6 6 WORKING IN POSTFEKO EM properties losses PO etc with the option to position the explaining legend at any of the four corners of the model Use Options gt Label colours to set the order in which colours are applied to the labels The different pages on the Model view control panel are listed below If the Visible check boxes are unchecked the associated objects are hidden or deactivated 1 The Main display options page
155. M TIMEFEKO 12 5 4 Ramp pulse RAMPE RAMP see figure 12 5 0 for t lt ti to t to t uo 1 for ti to lt t lt to to Ti u t ug for t2 to lt t lt t3 T to 12 5 t t3 t uo 1 22 for ti to lt t lt t to T2 0 for t gt t4 T T T T T T T 7 t t3 12 6 1 3 2 3 3 3 4 3 ui t uo t1 i to t3 t4 t Tis meee i H T gt Figure 12 5 Ramp pulse Example Pulse form RAMP k tO Impuls Duration T taul tau2 20 0E 09 15 0E 09 5 0E 09 10 0E 09 5 Double exponential impulse second type 0 z t to up e 71 u t Example Impulse form DBLEXP Time tO Parameter taul 20 0E 9 70 0E 9 e T2 DBLEXP DBLEXP see figure 12 6 for t lt to for t gt to E t to 12 7 Parameter tau2 5 0E 9 December 2005 FEKO User s Manual 12 6 THE PROGRAM TIMEFEKO 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 1 2 0 2 4 6 8 10 t x 10 Figure 12 6 Double exponential impulse second type 12 3 2 Definition of the frequency block The upper frequency limit fmax and the number of frequency points N are defined in the frequency block FREQUENZ FREQUENCY Example FREQUENCY Upper frequency limit Number of frequency points 250 0E 06 34 The maximum frequency fmax should be large enough such that the whole spectrum of the exciting pulse is covered For example for the Gaussian pulse GAUSS of section 12 3 1 we find f3aB ln v2 x 0 1874 with a as defined in equa
156. Manual 2 12 GENERAL COMMENTS J M el Plane of magnetic symmetry la gt Hu Figure 2 10 Magnetic symmetry plane When using magnetic symmetry there is a reduction in the computational time when determining the matrix elements The order of the matrix equation is reduced which leads to a further reduction in the computational time and reduces the amount of memory needed to determine the matrix elements 2 4 4 Example of the application of symmetry In figure 2 11 a dielectric sphere is shown with a linear polarised incident electromagnetic field The full description of the problem is given in example_04 in the Examples Guide Only the use of symmetry is described here Z l Figure 2 11 Dielectric sphere with incident field The plane z 0 xy plane is a plane of geometric symmetry because the excitation does not have any symmetry in this plane The plane x 0 yz plane is a plane of electric symmetry because the electric field is perpendicular to this plane and the magnetic EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 13 field has a tangential component only Similarly the electric field only has a tangential component in the y 0 plane and the magnetic field is perpendicular This is thus a plane of magnetic symmetry To indicate the reduction in time and resources through the use of symmetry a table is given below Type of Symmetry Nu
157. O OPTFEKO and TIMEFEKO the error is fatal and the entire solution will be lost In the case of EDITFEKO the user will get an option to switch to the FEKO LITE mode and can still save his work Thus it is usually preferred to check in a licence where only EDITFEKO is checked out In addition the Server item on the main menu allows Shutdown and Reset For security reasons both these operations are restricted to users with administrative priviledges Windows or the root user UNIX or the user account under which the licence server is running Generally it should only be necessary to Reset the licence server when modifying the licence file for example when obtaining a new licence file from EMSS or when changing the port Note that resetting the licence server will check in all licences such that all active user jobs will be terminated similar to when checking in individual licences Users should not need the Shutdown option This is only required to stop the service such that the files can be deleted but this will usually be done by the installation program Note also that once the licence server has been shut down it must be restarted on the server itself the licence manager cannot connect to the service if it is not running Please check the Getting started manual for further instructions on the floating licence server installation and startup 3 3 Determine the machine code Finally the machine codes of the current machine can be display
158. Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 15 grid DTHETA 5 00 deg and DPHI 5 00 deg 2701 sample points angular range THETA angular range PHI radiated power 2 50 182 50 deg 2 50 362 50 deg 1 05642E 03 Watt 0 00 180 00 deg 0 00 360 00 deg 1 04095E 03 Watt Polarisation dependent radiated power horizontal polarisation 3 63158E 04 Watt 34 89 7 vertical polarisation 6 77792E 04 Watt 65 11 S polarisation 5 19105E 04 Watt 49 87 7 Z polarisation 5 21845E 04 Watt 50 13 7 left hand circular pol 7 13564E 04 Watt 68 55 right hand circular pol 3 27386E 04 Watt 31 45 where the first line of total power is calculated assuming that each specified point lies at the centre of an incremental integration area The effective area is therefore slightly larger than the area defined by the start and end angles The second line gives the power integrated over an area defined by the start and end angles For example one may request an integration from y 0 to y 350 and Y 5 to Y 175 both in 10 increments in which case the first total will give the total power through the sphere One may also request the integration from y 0 to y 360 and Y 0 to Y 180 in which case the second total will give the correct total power through the sphere The polarisation dependent power on the second block is calculated according to the effective area of the second line The
159. RIC EDGES with MoM triangle no points of the triangle no type length m media KORP KORM POIP POIM POIA POIE 1 3 2 8284E 01 0 1 1 2 1 1 3 2 2 3 2 0000E 01 0 1 1 3 2 3 1 3 3 3 2 0000E 01 0 1 1 26 3 3 1 2 electr info of symmetry magnet info of symmetry yz XZ xy status yz XZ xy status 0 0 42 unknown 0 0 42 unknown 0 0 43 unknown 0 0 43 unknown 0 0 44 unknown 0 0 44 unknown In addition to the data that is given for the metallic triangles the following columns are provided POIA POIE KNP and KNM The column POIA contains the number of the corner point of the triangle in KORP where the basis function for magnetic surface current begins and the column POIM contains the number of the end point of the triangle where the basis function ends The sizes KNP and KNM are the lengths when the vertices are connected to the middle of the opposite edge in the triangles KORP and KORM The symmetry informa tion is shown for the basis functions of both the equivalent electric or magnetic current densities The data for the segments follows the data for the triangles DATA OF THE SEGMENTS No label xl in m yi inm z in m nodes medium x2 in m y2 in m z2 in m length in m radius in m 1 O 0 00000E 00 0 0000E 00 2 7700E 00 1 O 0 00000E 00 0 0000E 00 2 1625E 00 6 0750E 01 2 7700E 02 2 O 0 0000E 00 0 0000E 00 2 1625E 00 1 2 O 0 0000E 00 0 0000E 00 1 5550E 00 6 0750E 01 2 7700E 02 3 O 0 0000E 00 0 0000E 00 1 5550E 00 2 3 O 0 0000E 00 0 0000E 0
160. SF card Figure 10 8 Impressed line current with a linear current distribution December 2005 FEKO User s Manual 10 30 DESCRIPTION OF THE CONTROL CARDS The following restrictions apply when using the impressed current elements e It is not possible to attach the impressed current to a wire segment in the FEKO model If the impressed current is making electrical contact with a triangular surface current element the AV card should be used e When modelling dielectric bodies with the surface equivalence method the current element must be in the free space medium i e outside the dielectric bodies The material parameters of this medium can however be set with the EG and or GF cards e When used with the spherical Green s function the current element must be outside the dielectric spheres e The current segments may be joined with each other and with the AV card to form long paths and or closed loops The point charges which arise when the current does not go to zero at an end point or when there is a current discontinuity at a connection point are not taken into consideration This is required to model for example the case where radiating lines are terminated in a non radiating structure If these charges must be considered explicitly the line current should be modelled by a row of Hertzian dipoles see the A5 card Note however that the constant line charge along the current segment is correctly taken into a
161. THE POSSIBILITY OF SUCH DAMAGE 15 3 Copyright of libcurl EDITFEKO makes use of libcurl to connect to the EMSS web site to check for updates The copyright declaration for libcurl is as follows COPYRIGHT AND PERMISSION NOTICE Copyright c 1996 2005 Daniel Stenberg lt daniel haxx se gt All rights reserved Permission to use copy modify and distribute this software for any purpose with or without fee is hereby granted provided that the above copyright notice and this permission notice appear in all copies THE SOFTWARE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM DAMAGES OR OTHER LIABILITY WHETHER IN AN ACTION OF CONTRACT TORT OR OTHERWISE ARISING FROM OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE Except as contained in this notice the name of a copyright holder shall not be used in advertising or otherwise to promote the sale use or other dealings in this Software without prior written authorization of the copyright holder EM Software amp Systems S A Pty Ltd December 2005 COPYRIGHT NOTICES AND ACKNOWLEDGEMENTS 15 3 15 4 Qwt project usage For CADFEKO the figures in the mesh information dialogs are based in part on the work
162. Up to layer a Scale factor o To import polygons from FEMAP you must create boundary surfaces using lines rather than edges This card supports all the parameters described in the general section of the IN card above The label selection uses the FEMAP layer numbers which are converted to FEKO labels Wires must be meshed into elements which are imported as segments surfaces into tri angles or quadrangles which are imported as FEKO triangles and boundary surfaces are imported as polygons The boundary surface must be bordered with line curves rather than edge curves The user can also elect to import points from the neu file All points defined as such in FEMAP are then available in PREFEKO as points as if they were defined by DP cards of the form Pxxx where xxx is the point ID in FEMAP This may be used for example when attaching additional structures to a geometry partly created in FEMAP In addition the coordinate values of the point are available as variables in PREFEKO For example the variables p1234x p1234y and p1234z give the coordinates of the FEMAP point with ID 1234 Note that points are not included by default It should be remembered that it is not possible to specify a wire radius in FEMAP Thus the wire radius must be specified by an IP card preceding the IN card Similarly when specifying the surface of a dielectric the IN card must be preceded with the correct ME card completely analogous to the case
163. Y CARDS 9 2 29 PH card This card creates a triangular or quadrangular plate with a circular or elliptical hole as shown in the card PH Create a plate with a hole Max edge length on curve Scale second half axis with The hole can be used for example to attach a cylinder ZY card to the plate and it can be filled with the KR card Parameters S1 The corner where the hole is located also the hole s centre S2 The second corner of the plate 53 The third corner of the plate If this field is left empty a trian gular plate is created S4 The fourth corner of the plate S5 A point on the line S1 S2 that forms the starting point of the circle or ellipse bordering the hole The special case where S5 is identical to S2 is supported but due to the resulting geometry yields triangles with very small angles Maz edge length on curve The maximum edge length of the triangles along the edge of the hole in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Scale second half axis If this parameter is empty or is set to 1 a circular hole is created If set to 2 an elliptical hole is created Here 2 gives the ratio of the two half axes where a is the distance S1 S3 It is recom mended to generate the plate with a CAD system if the elliptical hole has an extremely small or extremely large axial ratio as the distortion formulation used in PREF
164. a pcr file and then for a sub sequent run just read again from this file Since the FEM pre conditioners depend only on the FEM matrix even for combined MoM FEM hybrid methods this method is useful for instance when only the MoM part of a problem setup has changed Iterative solutions are used for instance for the MLFMM or the FEM There might then be situations where during the iterations the residuum is decreasing but not reaching the specified stopping criterion Instead of waiting very long until the maximum number of iterations has been reached the user can press Ctrl C or Ctrl Break under Windows or send the SIGINT SIGTERM signals under UNIX so that FEKO will stop with the iterations and resume with the further processing e g far field computations using the solution associated with the best residuum obtained so far To really interrupt a FEKO job Ctrl C or Ctrl Break must be pressed a second time or the corresponding signal must be sent once more December 2005 FEKO User s Manual 10 62 DESCRIPTION OF THE CONTROL CARDS 10 2 22 CM card This card is used to couple FEKO with the transmission line simulation program CableMod or the PCB tool PCBMod to calculate the coupling of electromagnetic fields into trans mission lines The AC card is used for the case of radiation by these lines CM Near fields for CableMod File name Compute near fields at points along transmission lines specified in a CableMod
165. a zo a yfoo m zfoo ca vo of zoo om Set to global Set to woikplane Figure 4 4 Local coordinate panel of the Create cuboid dialog geometry creation dialog is opened This is only done when opening the dialog the coordinates are not modified if the workplane is modified after opening the dialog If no 3D view exists the local coordinates are matched to the global coordinates 4 6 3 Point entry Some fields on the geometry creation dialogs amongst others allow entering values by clicking with the mouse on the 3D view If such fields have focus their background colour changes to yellow By clicking on the 3D view the coordinates of the selected point determined using the active snap mode see section 4 3 3 of the particular view are entered into the field and the focus shifted to the next field It is also possible to click on a named point or variable in the tree This point is then added in all the active fields or in the case of a variable the current field This allows creating geometry with a series of clicks on the 3D view and one click on Create in the dialog For one dimensional input fields such as the radius of the sphere the value is calculated from the specified point and the result entered into the field Where the input field requires a vector the vector is considered to lie from the origin to the selected point It is important to realise that the sequence of operations ca
166. a NURBS surface from specified control points PB creates a paraboloid PH creates a flat plate with an elliptic hole PM creates a polygonal shape that is meshed into triangles 3In general all the geometry cards must appear before the EG card Exceptions are the IN card when including pre files with control commands and the DP and TP cards when defining points for the AP card December 2005 FEKO User s Manual DESCRIPTION OF THE GEOMETRY CARDS PO PY QT QU SF SY TG TO TP UT UZ WG ZY applies the Physical Optics approximation creates a polygonal surface for use with UTD creates a dielectric or magnetic cuboid meshed into tetrahedral elements creates a dielectric or magnetic cuboid meshed into cuboidal elements remeshing and adaptive mesh refinement enters a scaling factor with which all dimensions are multiplied utilises symmetry in the construction of the geometry transformation i e translation and rotation of the geometric structures creates a toroid transforms a point parameters for the uniform theory of diffraction UTD creates a cylinder for use in the UTD region creates a parallelogram consisting of a wire grid creates a cylindrical element EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 3 9 2 Alphabetical description of the geometry cards 9 2 1 card The card is not a command but defines a comment line Everything that is
167. a PRE file with that name already exists Hence if one runs CADFEKO from EDITFEKO on a model for which only a PRE file exists CADFEKO will open with a new nameless model If this model is saved to the same name it will overwrite the existing PRE file Hence one should generally create models in CADFEKO and then run EDITFEKO Note that when running PREFEKO or FEKO the current file is saved without confirmation EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 5 Select Run Solution options to set the command line options for the various kernel components The meaning of the options can be found in the chapters dealing with the separate components The advanced fields on these dialogs allows typing parameters as one would on the command line It is possible to launch the solution on a remote machine If the Remote FEKO execution item is checked EDITFEKO launches the solution on the host specified in the Remote execution group of the FEKO tab of the Solution options dialog Remote launching must be set up as described in the Installation section of the Getting started manual See section 8 2 3 If Parallel FEKO execution is checked the solution is launched on a parallel cluster as defined in the Parallel execution group of the FEKO tab of the Solution options dialog Unless the parallel job is also a remote one the local machine must be the first host name in the configuration See section 8 2 2 5 2
168. a number of edges for example a polyline The two lofted curves must have the same number of edges the loft can be considered to connect each pair of edges Tf this is not the case points can be imprinted see section 4 7 7 on one of them to rectify this Curves with more than two edges joining at one point are not allowed The preview shows how the curves will be connected The Loft dialog allows reversing the start and end points of one edge in the case where the two edges are not created in the same or desired direction December 2005 FEKO User s Manual 4 28 WORKING IN CADFEKO Figure 4 14 Example of a surface with an edge that just touches the axis of rotation 4 7 7 Projection and imprinting points In some cases it is desirable to create specific points edges or faces on a given geometry for example to allow attaching other structures to the model to specify a finer mesh size along a curve or to create metallic patches on dielectric objects The Imprint points operation allows placing specified points on the selected part Points can only be imprinted on one part at a time The Imprint points dialog allows a list of points to be specified using standard point entry see section 4 6 3 in either global or local coordinates The specified points are projected onto the closest point on the selected part either on a face or an edge Points may not be imprinted on existing points The imprint operation creates a new entry
169. a spherical aperture I Also sample along edges apeo n gt EZ A 5 s2 rT s E file name TE E Start from point number Number of points along amp 2 sis Number of points along s 4 Amplitude scale factor Po Phase of aperture degrees Po Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations field data In this group one selects between Load field data from efe hfe file i e from efe or hfe files previously calculated with FEKO Load field data from ASCII text file the format of these files are documented below or The field data follows in the pre input file described below aperture Here one may select a planar cylindrical or spherical aperture For a planar aperture one may elect to use only electric or mag netic fields this radiates in both directions see comment below Also sample along edges This item is used to determine if dipoles should lie on the edges of the aperture or not see figures 10 9 to 10 12 When checked the outer dipoles lie on the edges when unchecked the dipoles lie half an increment away from the edges Dipoles should not lie on December 2005 FEKO User s Manual 10 32 DESCRIPTION OF THE CONTROL CARDS the edges of two apertures that have a common side otherwise two dipoles may have the same location and polarisation If this is the case
170. abel selection all elements are imported December 2005 FEKO User s Manual 9 34 DESCRIPTION OF THE GEOMETRY CARDS Scale factor An optional constant scaling factor can be applied to the imported geometry This is necessary for example if separate CAD files with different units must be imported or if the pre is for example created using mm while the CAD file is constructed using inches as unit It should be noted that the scaling factor specified here is applied in addition to any scaling factor that may be set with the SF or TG cards 9 2 18 1 PREFEKO file This option is used to include cards and commands such as variable definitions etc from a separate file One may for example create a single file with an antenna which is then imported into different environment models IN Include an external file Include PREFEKO file y File name EJ For this option the file name is the only parameter This file is included as if it was part of the master pre file These include files usually have the extension inc but can have any extension The cards and instructions in the included files are processed as if they were part of the main file Therefore points and labels defined in the included file remain valid in the remainder of the main file Note that it is also possible to use such an IN card in the control section of the pre file for instance to import some feed model When reading a PREFEKO file it is
171. able to both the TG and AR cards Finally the pattern is shifted to the specified location If the AR card is used simultaneously with a ground plane BO card FEKO includes the influence of the ground plane on the radiation pattern The imported pattern must therefore be the free space radiation pattern of the antenna in the absence of the ground plane If this is not the case the influence of the ground plane is considered twice The use of the PW card to specify the radiated power is allowed The field amplitudes ESF and E will be scaled accordingly Multiple radiation patterns can be used simultaneously and also with other sources such as an incident plane wave In such a case the coupling is not considered when the radiated power is determined The AR card cannot be used with special Green s functions for a layered sphere or for a layered substrate The format of the data depends on the value of the parameter Read pattern data from e an ffe file ffe file With this option the radiation pattern is read from a ffe file created with FEKO using the DA and FF cards All the data of the radiation pattern angles and field values are determined from the file The user should ensure that for example the frequency is correct If an antenna is analysed with FEKO the far field can be exported to the ffe file using the commands for 5 angle increments DA 0 0 1 0 0 FF 1 37 73 0 0 0 5 5 EM Software 4 Systems S
172. ach iteration of the design In such a case the input impedance is plotted and converted into a value series before the PRE file is modified and the problem is re simulated In the 3D view all results are updated immediately if the result changes For the 2D however the user is prompted to Reload or Serialise If a series is serialised it is converted to a value series which no longer depends on the result file This also implies that the series cannot be modified in a way that requires the original result It is possible for example to switch from dB to linear as this requires only the current values but it is not possible to switch between electric and magnetic fields The control panel that referenced the result file is then replaced with a table of data values If the update option is selected POSTFEKO will load the new information from the BOF file and update the graph EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 15 6 5 8 PFG graphs and importing GraphFEKO WFG graphs Any 2D graph can be saved to a PFG graph Note that this is a snapshot of the graph at the save time the PFG graph stores the result data rather than a reference to the applicable BOF file If the graph is modified afterwards the save command will save the modified graph as part of the session the PFG graph will remain unchanged unless it is explicitly saved again Finally it should be noted that loading a PFG graph loads
173. ach time but there is an option to store this to a file and load again to save time when the geometry stays constant say for multiple runs using different frequencies The options are e No sha files normal execution Shadowing information is not stored or read the default behaviour e Save shadowing to a sha file The PO shadowing informa tion is written to a sha file for later reuse e Read shadowing from a sha file The PO shadowing infor mation is read from the sha file i e the ray tracing part is skipped For large models this can result in considerable time saving December 2005 FEKO User s Manual 9 78 DESCRIPTION OF THE GEOMETRY CARDS e Read sha file if it exists else create it If a sha file exists the PO shadowing information is read from this file Otherwise the information is calculated and saved in a sha file for later use Use multiple reflections When this item is checked multiple reflections are considered for the ray tracing The number of reflections that must be consid ered is set in the Number of reflections dialog This parameter determines the number of reflections to be taken into account for triangles with labels in the specified range For example the Number of reflections must be at least 2 to calculate the scat tering from a dihedral and at least 3 for a trihedral Increasing the number of reflections that must be considered significantly increases computation time
174. ade followed by a dialog prompting for the name of the file to export to CADFEKO currently exports Parasolid version 16 1 but with the correct schema file this can also be imported into older versions of Parasolid Only the final geometry is exported Exporting and importing the same model looses the entire creation tree Parasolid models are inherently limited to a 1000x1000x1000 unit box centred at the ori gin CADFEKO introduces a scaling factor to counteract this see section 4 6 1 The Scale factor field on the Export Parasolid model dialog displays the factor by which the model in CADFEKO units must be multiplied to convert it to the units in the Para solid model A scale factor of 0 1 implies that the dimensions of the saved Parasolid model are one tenth of the native dimensions as used in CADFEKO Typically programs that import Parasolid models allow specifying a factor with which the Parasolid model must be multiplied during the import This must then be the inverse of the scale fac tor reported by CADFEKO For convenience the import factor is stored in a separate file the filename is derived by adding info to the full Parasolid filename for example export_geometry x_t info in the same directory as the Parasolid file If the model needs to grow larger than 500 units the extents must be increased If however the model is smaller than 50 units the extents can be decreased This is not recommended unless the model is very small
175. age window is collapsed the View menu contains Tree or Messages which can be used to show them again The toolbars can be docked at any of the four sides or dragged free into their own windows click and drag the double lines on the top or left When a December 2005 FEKO User s Manual 4 4 WORKING IN CADFEKO toolbar is dragged to a location where it may be docked it is drawn with a thin outline instead of the normal border The toolbars can be shown hidden from the View menu or by right clicking on the main menu and selecting the appropriate item CADFEKO strives to be as unrestrictive as possible For example the workplane and the view orientation may be changed or a new variable defined while creating geometry without having to close the geometry creation dialog first If a new dialog is opened while another dialog is open all the input fields on the first dialog are disabled until the new dialog is closed If a number of dialogs have been opened they will become available in reverse order as each dialog is closed The dialogs themselves are not disabled thus they can still be moved on the screen Some operations such as modifying a variable may change the model These operations are not allowed while working with other tools that operate on the model In addition a second dialog cannot be opened for the same item For example if a geometry creation dialog is opened while the Edit workplane dialog of a 3D view is open the wo
176. aim function in two different ways We differentiate between the local aim function and the global aim function The local aim function f is defined per solution block The global aim function Z is calculated from a combination of the local aim functions In some cases the global aim function is defined directly since it does not make sense for these functions to be calculated on a per block basis In general the global aim function can either aim to reduce the average of the local aim functions or to minimise the maximum of the local aim functions If an average local aim function should be minimised the global aim function Z is defined by ae L gt gt i Na 27 If the maximum local aim function should be minimised minimax principle the global aim function is defined by Z maxi 1 Np fi In this section the errors fi for each of the target quantities is defined When doing optimisation quite often there is not only one optimisation target For instance one might want to optimise the antenna gain but at the same time get the impedance right Or one might want to optimise an antenna pattern and use different shape functions for the horizontal and vertical cut planes Each global aim function specifies one type of observable to be optimised Any number of these aim functions can be combined linearly to optimise more than one observable at a time In this case each of these aim functions get an additional weighting factor associat
177. ain mesh formats see IN card in section 9 2 18 then also labels can be imported for instance the NASTRAN property gets converted into a FEKO label In principle FEKO labels can be e A positive integer number including zero then also valid expressions like 3 i 2 can be used which are evaluated e A string of characters valid are a z A Z 0 9 and the underscore _ op tionally followed by a variable which starts with the sign Such variables at the end are evaluated and replaced by the corresponding numerical value rounded to integer Note that string labels are case insensitive in FEKO i e labels Roof and ROOF are treated identically inside FEKO EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 9 Labels Feed BHorn BSubRef E MainRel Figure 2 8 Example demonstrating the usage of labels display of labels in colour with legend in POSTFEKO So for instance these labels are valid 23 5 k j 2 LeftWing Front_Door Part i while these labels are not valid Left Wing invalid character 23 negative integer Part_ i_ k two variables With the CB card FEKO allows to change labels e g after having imported some geom etry A powerful wildcard globbing is supported there see section 9 2 6 for details At certain FEKO cards one can specify ranges of labels or also sometimes labels are incremented e g when using
178. al feed but requires both the inner and outer radii Parameters New source Add to sources Select segment Magnitude of source Phase of source Inner conductor radius Outer conductor radius S parameter impedance A3 Add a magnetic frill excitation New source Add to sources Select segment Set source position Apply source to last segment with label J Magnitude of source V fi Phase of source degrees fi Inner conductor radius Poo Outer conductor radius Set source coordinates S parameter impedance Ohm J New excitation replaces all previous excitations Additional excitation is added to previous excitations When this item is selected the Apply source to last segment with label field becomes active Here one specifies the label of the seg ment on which the TEM frill is placed If more than one segment has this label the source is applied to the last segment with this label Alternatively one may select the item Set source position then the feed segment is determined by specifying the Cartesian coordinates in the Segment centre group The position values are in m and are scaled by the SF card if Modify all dimension related values is checked Magnitude of the voltage Uo in V Phase of the voltage Uo in degrees Radius of the inner conductor of the coaxial feed Radius of the outer conductor of the coaxial feed The port impedance if this excit
179. all other surfaces will have label 0 x 0 yz plane only geometric symmetry y 0 xz plane ideal magnetic conducting plane z 0 xy plane ideal electric conducting plane 1 1 0 0 1 2 0 1 0 3 2 End of the geometry 1 0 1 0 0 Set the frequency 1 0 freq Excitation by means of an incident plane wave 0 1 1 1 0 90 0 0 Surface current density output for surface with label 1 4 1 1 Calculate the far field only in the direction of incidence 2 End EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO 12 11 For this example we have chosen a Gaussian pulse excitation with a 3 x 10 As discussed in section 12 3 2 f3gg is approximately 56 MHz such that we require a maximum frequency of at least 224 MHz We select a maximum frequency of 250 MHz The time shift selected for this example is 6 light metre and the structure dimensions is of the order of 1 metre Thus we believe that the time response should die out within 40 light metre or 133 ns Then equation 12 8 then yields N 34 The tim input file cube tim then contains Timefeko Example tim file Define the Pulse form GAUSS Parameters of the Gaussian pulse Time shift Exponent 2 0e 8 3 0e 8 Define the frequency block Gaussian pulse with a 3 0e 8 1 s i e _3dB 0 187 a 56 2 MHz kk Choose f_max gt 4 f_3dB 224 9 MHz use f_max 250 MHz Total time we want to analyse T 40 lightmetres 133 4 ns
180. all the PREFEKO and FEKO control cards These cards should not be used in the geometry section of the pre input file i e they should only be used below the EG card The control cards are used to specify for example the frequency and the type of excitation They also determine the required calculations such as the locations for near field calculations and the directions for far field calculations etc Card Description characters used to indicate a comment line Ax type of excitation e g an incident plane wave or a voltage source BO through the use of the reflection factor coefficient a ground plane can be inserted CF set the type of integral equation for perfectly conducting metallic surfaces CG the algorithm used to solve the matrix equation is selected CM Field calculation for CableMod coupling into transmission lines or PCBMod couling into a PCB CO inserts a dielectric and or magnetic surface on the elements DA creates additional files for the results DI enters the properties of the dielectric medium EN indicates the end of the input file FE calculates the near fields FF calculates the far fields FR sets the frequencies at which the calculations are to be carried out GF sets the Green s functions L4 adds a load between a metallic triangle and the ground plane for the planar multilayer Greens function LD defines a distributed load consisting of resistance inductance and capacitance LE
181. along the s direction first For cylindrical apertures it must have five parameters The angle y in degrees followed by the absolute value and phase of the component and the absolute value and phase of the Z component For spherical apertures it must have six parameters The angles Y and y followed by the absolute value and phase of the Y and components December 2005 FEKO User s Manual 10 36 DESCRIPTION OF THE CONTROL CARDS When the data is read from the pre input file the data must be in the normal column based input format and FOR loops etc may be used The four field components are the same as for the text data and must be entered in columns 10 characters wide from columns 51 to 90 The angle y must be in columns 40 to 49 and Y in columns 30 to 39 when they are required If both electric and magnetic fields are required all the electric fields are given first followed by the same number of magnetic fields Example of AP card usage As an example consider an open ended X band waveguide radiating through a hole in a large ground plane as shown in figure 10 13 Away from the aperture the plane z 0 is perfectly conducting i e the tangential electric field is zero while the magnetic field is not thus we will use electric symmetry Figure 10 13 Example of an open waveguide as an implementation of the AP card For this example the field is considered to be purely y directed i e it has only a y or s comp
182. also possible to specify which types of elements to cut away 6 4 Displaying 3D results It is possible to view results together with the geometry in the 3D view If the BOF file is not loaded POSTFEKO automatically loads it if any of the 3D result display buttons are clicked Multiple results are created by clicking the Add button the green sign at the top of the panel Each result can also be deactivated by unchecking Visible or removed from the view by clicking the Remove button the green sign above the pages A legend can be displayed for any quantity with up to four legends on the display at any given time If multiple results of the same type are displayed separate legends can be used for each result However it becomes difficult to differentiate between them It is therefore recommended to use one legend per result type and ensure that the scale limits of all the results are set to the same values The display is updated immediately if anything is changed on the control panel Thus the current state of the control panel is an accurate indication of what is displayed In December 2005 FEKO User s Manual 6 8 WORKING IN POSTFEKO addition all results are automatically updated each time FEKO is executed If a results file is changed in such a way that it contains a different structure other frequencies ad ditional solutions more field calculation requests etc POSTFEKO will try to maintain the selected entries bu
183. ample updating of the model and then running PREFEKO from EDITFEKO if the latter is already open CADFEKO also creates a default PRE file which imports the CFM file the first time the model is saved Since this file is edited by EDITFEKO to specify the control parameters it is never overwritten by CADFEKO 4 15 1 Solution options The Solution options item under the Run menu allows specifying parameters for the various FEKO components See See Chapters 7 and 8 The Advanced fields on these dialogs allows manually typing the options as would be done after the filename in a command line 4 16 Working with CADFEKO models in EDITFEKO Currently all control parameters frequency excitation etc must be specified in EDIT FEKO which can be launched from the Run menu in CADFEKO EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 47 4 16 1 Setting units CADFEKO has no direct support for specifying units FEKO however expects all input to be in metres The SF card in the geometry section of the PRE file can be used to specify the units For example if the model was constructed in millimetres an SF card with a 0 001 scale factor should be added to the PRE file 4 16 2 Referencing elements In EDITFEKO properties can be set on specific elements using their labels see sec tion 4 10 Segments have the label of the edge typically called Wire triangles that of the face typically Face
184. analyses involving objects of arbitrary shapes Changes in this manual with respect to the previous one of July 2005 Suite 5 0 are indicated as follows Sections that have changed from those in the previous version of the manual Sections that were newly added to this version of the manual 1 1 FEKO Overview The core of the program FEKO is based on the Method of Moments MoM Electromag netic fields are obtained by first calculating the electric surface currents on conducting surfaces and equivalent electric and magnetic surface currents on the surface of a dielectric solid The currents are calculated using a linear combination of basis functions where the coefficients are obtained by solving a system of linear equations Once the current distribution is known further parameters can be obtained e g the near field the far field radar cross sections directivity or the input impedance of antennas Electrically large problems are usually solved with either the Physical Optics PO ap proximation and its extensions or the Uniform Theory of Diffraction UTD In FEKO these formulations are hybridised with the MoM at the level of the interaction matrix This is a major step in addressing the problem of solving electromagnetic problems where the object under consideration is too large in terms of wavelengths to solve with the MoM but too small to apply only the asymptotic UTD approximation with high accu racy With the hybrid MoM PO or hyb
185. and runs into precision problems since using the default extents results in an unscaled Parasolid model removing the need to keep track of the scale factor Parasolid models can also be imported into CADFEKO Select File Import Geom etry Parasolid from the main menu This asks for a filename and then opens an Import Parasolid model dialog where the scale factor can be modified This Scale by factor is the factor by which the Parasolid model is multiplied as it is imported If the Parasolid model was created by CADFEKO and the INFO file is available the dialog will display the value in the file This value can then be changed For example if an antenna model was constructed in mm and then imported into an automobile model constructed in m a scale factor of 0 001 would be appropriate independent of any scale factor required by the definition of the model extents Note that importing a large model with a scale factor other than unity can be a very slow process Isolated vertices acorns in a Parasolid model are not the same as named points see section 4 5 1 in CADFEKO Hence they are not imported but CADFEKO writes their coordinates to the message window The required named points can then be created manually If Import bodies with faults are checked all parts in the file are imported even if they contain errors It may then be possible to for example explode such parts and delete only a few problematic surfaces Howeve
186. and tetrahedra that of the dielectric region typi cally Region Of course these names can be modified on the geometry or the mesh elements See section 4 13 2 for more details Since every region face edge has a unique label a typical model may contain a large number of labels Setting properties such as losses then requires a large number of cards To simplify this PREFEKO supports renaming multiple labels using the wild cards and where expands to any string and to any character For example renaming Wheel Face to Wheel will rename the faces Wheel1 Face1 and Whee12 Face17 and all others matching this pattern but not Whee110 Facel or Wheel1 Wire1 to Wheel They can then be referenced with a single name After renaming these elements the original names no longer exist i e referencing items using those names will not find any elements 4 16 3 Using variables and named points in EDITFEKO When exporting the CFM file CADFEKO includes all variables and named points with their current values These values are then imported by PREFEKO and can be used in the PRE file at any point after the IN card 4 16 4 Setting dielectric parameters In CADFEKO dielectrics are defined on the regions of complex bodies see section 4 8 Imported models often only have faces For this reason CADFEKO automatically con structs regions as part of a union of faces that form a closed body For all dielectrics the medium name is specifi
187. ane Magnitude of source v J Phase of source degrees J Coordinates of node Radius of the connection pin S parameter impedance Ohm Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Select triangle When this item is selected the Source label field becomes active Here one specifies the label of the triangle to excite The feed point is at the centroid of the triangle see figure 10 3 If there are more than one triangle with this label the excitation is placed on the one with the highest element number Alternatively the user may select the item Set source position and specify the Cartesian coordinates of the feed point in the Coordinates of node group These values are in m and optionally scaled by the SF card FEKO will excite the triangle whose centroid is closest to the specified coordinate Transform impedance to ground plane If unchecked the impedance is computed directly at the excitation point If checked an inductive approximation of the feed pin is used and the impedance is transformed to the ground plane Magnitude of source Magnitude of the voltage Uo in V Phase of source Phase of the voltage Uo in degrees Radius of the connection pin The radius of the coaxial probe feed pin in m This value is optionally scaled by the SF card EM Software amp Systems S A Pty Ltd D
188. ane are imported FEKO supports ranges of labels if the strings end in numbers So only one card is need to include for example all the labels from Assembly Part Face3 to Assembly Part Face12 Ranges do not include items with completely different names names that do not have a number or names where the number lies outside the range Note that the number as a whole is used not individual digits The example will include Assembly Part Face4 and Assembly Part Face11 but not Assembly Part Face and Assembly Part Face44 Fewer IN cards are required if elements are relabelled in CADFEKO Elements belonging to different parts cannot belong to the same label so forming a union of the model before meshing it can simplify matters See the Getting started manual for more details 4 17 Notes editor CADFEKO supports a rich text editor shown in figure 4 24 allowing adding com ments to a model This is opened from the main toolbar or by selecting View Notes The toolbar at the top contains buttons to Clear and Print the notes Undo Redo changes as well as the standard Cut Copy and Paste commands Multiple undo redo commands are supported There is no facility to Cancel any changes to the text as this may be achieved with the Undo command In addition the editor allows setting the font name font size font type bold italic underlined and text colour Finally it allows setting the justification If no notes have been
189. ang formulation I Decouple with moment method Parameters Perfectly conducting cylinder Select this option if the Fock area is resembles a cylinder Perfectly conducting sphere Select this option if the Fock area is resembles a sphere Triangle labels The label of the metallic triangles that form the surface of the Fock area e g the surface of the cylinder Axis start Axis end point These dialogs are only visible for Fock cylinders and should correspond to the start and end points of the cylinder axis Sphere centre point This dialog is only visible for Fock spheres and should correspond to the centre of the sphere Formulation of the Fock currents The type of process for the Fock currents either the Method by Daniel Bouche or the Method by Louis N Medgyesi Mitschang Decouple with moment method Check this item to force FEKO to neglect the coupling be tween the MoM and Fock regions so that there is no feedback by which the Fock currents may influence the current distribution in the MoM region This option which is particularly applica ble when the MoM and Fock regions are not in close proximity should result in a considerable reduction in computational effort and storage space The radius of the cylinder or sphere does not have to be defined It is determined by the distance to the metallic triangles with the label specified in Triangle labels The cylinder Fock currents can also be applied to cones KK
190. anged without having to close the dialog that caused the error 4 6 2 Local coordinates All primitive geometry objects in CADFEKO are defined in global or local coordinates The default coordinate system can be specified by selecting Options Preferences from the main CADFEKO menu but it can be changed on each geometry dialog If the Use global coordinates box on the creation dialog is unchecked the Local tab as shown in figure 4 4 becomes active Specification of the local coordinates is very similar to specifying workplanes see section 4 3 1 The Origin field specifies the origin of the local coordinates Changing this value will translate the coordinates and thus the position where the new object will be created The U vector and V vector fields define the directions of the U and V axes and control the orientation of the object The third axis N is normal to the U and V axes The Set to workplane button sets the local coordinates to that of the workplane in the current view Thus the workplane tools can be used to define and manipulate the workplane and then the local coordinates fitted to this If the preference is set to local coordinates the Use global coordinates box is unchecked and the local coordinates initialised to the workplane of the active view each time a EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 17 A Create cuboid 128 x Geometry Local Sal vo v
191. ase of I dl Phase of the complex amplitude l in degrees x y z position Coordinates of the position of the dipole in m These values are optionally scaled by the SF card Y angle Orientation of the dipole in space Y in degrees is the angle between the dipole and the z axis p angle Orientation of the dipole in space in degrees is the angle between the projection of the dipole onto the plane z 0 and the x axis The dipole moment of the electric dipole is given by Il p Jw The power radiated by the dipole in a free space environment is given by _ B Zro IU _ wuri P 127 127Z Fo FEKO however considers the properties of the medium in which the dipole is located as well as the coupling of the dipole with surrounding structures or other sources for example other Hertzian dipoles in an array antenna when calculating the power radiated by the Hertzian dipole EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 2 9 A6 card This card specifies excitation by an elementary magnetic dipole Parameters New source Add to sources Electric ring current Magnetic line current Magnitude of Phase x Y z position Y angle p angle A6 Magnetic Hertzian dipole New source Add to sources Electric ring current m nIA C Magnetic line current Mm Imt jo Magnitude of A Am 2 J Phase degrees Dipole position x
192. assigned by a new LA card All structures created before the first LA card or if no LA card is present is assigned the default label which is 0 number zero Label names can be an arbitrary string using the characters A Z the digits 0 9 or also the underscore _ See section 2 3 for details also with respect to label increments or label ranges 6The definition Ax stands for any of the control cards AO Al A2 EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 65 9 2 26 ME card When solving the fields in dielectric objects by means of the MoM MLFMM surface or volume current methods or by means of the FEM this card must be used to distinguish the different media or to create segments and metallic triangles within the dielectric Furthermore this card is used to switch between the generation of metallic triangles and triangles that represent the surface of the dielectric Another special case is when metallic triangles represent the surface of a dielectric object e g a dielectric that has been coated with metal ME Define a dielectric region Type of triangles Metallic triangles in a homogenous medium Triangles representing the surface of a dielectric region C Metallic triangles representing the surface of a dielectric region Index of medium A Index of medium B All segments below this card will lie in medium A The triangles following this card represent the bo
193. ate with three internal points generated using a PM card is shown in figure 9 34 Note that there are node points at Q1 Q2 and Q3 A F D E Figure 9 33 Example for the PM card from demo_PM1 pre Figure 9 34 Example for the PM card with internal mesh points from demo_PM2 pre December 2005 FEKO User s Manual 9 76 DESCRIPTION OF THE GEOMETRY CARDS 9 2 31 PO card With this card the application of the physical optics approximation is possible PO Apply the PO approximation Use PO on all surfaces with label optionally up to label e Do full ray tracing Assume all surfaces to be illuminated E Full ray tracing illumination only from outside F Use symmetry in ray tracing TF Decouple with moment method Use multi level boxing to speed up ray tracing C Do not use the boxing algorithm Program determines maximum triangles box C Specify maximum triangles box below Maximum triangles box Save read PO shadowing information No sha files normal execution C Save shadowing to sha file Read shadowing from sha file Read sha file if it exists else create it F Use multiple reflections Multiple reflections Number of reflections Wo vis files normal execution C Save visibility to vis file C Read visibility from vis file Read vis file if it exists else create it Parame
194. ated with the volume equivalence principle e g the hand of a user around a mobile phone but the dielectric bodies must be outside the sphere An example of the use of the GF card for a sphere is given in example_15 Examples Guide Figure 10 23 Example of a sphere consisting of 4 media core and 3 layers indicating the layer numbering December 2005 FEKO User s Manual 10 90 DESCRIPTION OF THE CONTROL CARDS 10 2 30 3 Planar multilayer substrate GF Specify Green s functions Homogeneous medium C Layered dielectric sphere Planar multilayer substrate Conducting ground planes M Top Y Bottom Number of layers 1 2 Thickness Infinite Z value atthe top of layer 1 When this Green s function is selected the EM interaction of a layered dielectric substrate located in the xy plane is taken into account The Green s function can also take the effect of a top and or bottom ground plane into account This formulation has been popularised by its application to planar microstrip circuits and antennas but it is applicable to a larger class of EM problems e g buried antennas Parameters Conducting ground planes By checking Top and or Bottom the user can choose whether to have ground planes at the top and or bottom of the multilayer substrate If a ground plane is present metallic structures and field computations are not allowed
195. athematically positive sense around the axis direction The dialog shown in figure 4 8 also provides buttons to set the rotation axis to the principal axes of the global and local coordinate systems The rotation is applied to the object not its local coordinates The Translate dialog shown in figure 4 9 requires a start and end point from which it calculates the translation distance and direction The Mirror operation requires a plane This is specified via the dialog shown in figure 4 10 and is similar to the specification of the workplane The dialog also provides buttons to select from a number of common planes The Scale transformation requires an origin in global coordinates and a scale factor as shown in figure 4 11 Scaling is done around the origin specified on the scaling dialog not around the centre or origin of the object or the model 4 7 2 Multiple transformed copies Parts can be copied and transformed multiple times via a single command Select Copy special from the pop up menu or Edit Copy special from the main menu The transform dialog then contains the Number of copies field shown in figure 4 12 This will make the specified number of copies of each selected part With rotation the nt new part will be rotated with a single transformation through n times the specified rotation angle For translation the nt new part will be translated by n times the specified translation distance For the mirror operation only
196. ation is used in an S parameter calculation If this field is empty or 0 the value specified at the SP card is used This value is ignored if no SP card is used EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 15 The vector of the excitation points from the start point to the end point of the segment i e in the direction in which the segment was created with the BL card The excitation is not as in the A2 card an impressed electric field strength but is a magnetic ring current As a rule of thumb the radius of the inner conductor must be the same as the radius of the segment and that the outer radius should be 2 to 3 times the size of the inner If an impedance Z is desired then the following relation can be used Z 600 In Outer conductor radius Inner conductor radius to determine the outer radius For Z 50 Q the outer conductor radius should be equal to 2 3 times the inner conductor radius December 2005 FEKO User s Manual 10 16 DESCRIPTION OF THE CONTROL CARDS 10 2 7 A4 card This card creates a coaxial attachment feed approximation for use in connection with the Green s function for planar substrates with a metallic ground plane GF card sec tion 10 2 30 A4 Coaxial attachment feedback approximation New source C Add to sources Selecttriangle C Set source position Source label see manual J FF Transform impedance to ground pl
197. ation oc curs if the value for lambda deviates sufficiently little from the value which gives the arithmetic mean for the interval containing the minimum Here lambda is the factor with which to proceed in the given direction in order to minimise the aim function The product of ITOL and the present value of lambda yields the factor TOL1 which among other characteristics can lead to the termination of the interval reduction Due to the implemented procedure the present value for lambda can in such a case be already a few orders of magnitude smaller than the specified value of LAMBDA In case this value was chosen very small for example 1 0E 3 the value used for ITOL should be increased accordingly for example 1 0 so that the number of interval re ductions executed per line search stays within limits and that the optimisation is not terminated prematurely Fletcher 1 Polack 2 This selects the desired procedure to determine the new direction for the line search from the current gradient A 1 indicates that the new direction will be determined as by the Fletcher Reeves algorithm whereas a 2 refers to the variation by Polak Ribiere In general the Polak Ribiere formulation is preferred as it results in less steps to minimise the aim function and to a certain extent allows a restart Restart parameter 0 1 2 3 This parameter sets the cyclical restart of the complete Fletcher Reeves method from the
198. ations Use only some labels for field calculation Use label selection when calculating near and far fields Only the currents on structures with a label in the range specified in the fields Start at label and End at label are used during field computation If a basis function extends over for example two triangles it is included if either triangle of the tri angles lies in the specified range Origin of offset coordinate In this group the Cartesian coordinates of the transformed ori gin are specified Each of z y and z is scaled by the SF card if the SF card is used A possible application of the OF card is for example to calculate the near field on the surface of a sphere whose centre does not lie on the origin The OF card transforms the origin of the coordinate system to the centre of the sphere such that the near field calculation can be executed in spherical coordinates EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 101 10 2 38 OS card With this card the currents on the surfaces and the segments can be extracted OS Output currents Extract currents to output file No currents All currents C Only the currents on triangles Only the segment currents C Currents on structures with single label Currents on structures with label range C All segment currents to rsd CableMod file Segment currents label range to rsd file Extract currents sta
199. ault configuration a main menu and toolbar split into the Standard and Selection toolbars at the top a toolbar split into the Create geometry and Modify geometry toolbars and tree view on the left a message window and status bar at the bottom and a window area containing the 3D views and or the notes editor A CADFEKO Untitled 3D view 1 amp File Edit View Geometry Mesh Find Options Run Windows Help RAID sa RA fy UR Named points Dielectric Teflon ne Es teate geometry cuboid Cubor H Edges Add dielectric medium Teflon E Regions i P E Setting geometry properties MResion2 Dielectric Set region Region2 of Cuboid1 to Dielectric Teflon Figure 4 1 The main CADFEKO display The message window displays messages about user interaction such as geometry creation and undo redo commands It also shows more details about error messages The status bar shows the snap mode and the coordinates of the current cursor position in global coordinates using the selected snap mode This works with standard point entry see section 4 6 3 or by pressing lt Ctrl gt lt Shift gt while moving the mouse in the 3D view The tree view and message window can be resized by dragging the splitter bars The panels can be collapsed by dragging the splitter all the way to the edge and shown again by dragging the splitter away from the edge When the tree or one of its halves or the mess
200. ave been specified before at a DP card Start point of line When using local mesh refinement with respect to a line then here the name of the start point of the line is entered the point must have been specified before at a DP card End point of line When using local mesh refinement with respect to a line then here the name of the end point of the line is entered the point must have been specified before at a DP card CableMod rsd file When using local mesh refinement with respect to a cable harness then here the filename of the CableMod rsd file is specified December 2005 FEKO User s Manual 9 86 DESCRIPTION OF THE GEOMETRY CARDS Global finer mesh size When a global mesh refinement is used then this is the new mesh size which shall be applied Mesh coarsening is not supported only mesh refinement So when the new mesh size is larger than the existing mesh size simply no mesh refinement will be done Distance D1 Reference distance d for the mesh refinement discussed below Mesh size at D1 Mesh size s at the reference distance di discussed below Distance D2 Reference distance da for the mesh refinement discussed below Mesh size at D2 Mesh size sa at the reference distance d2 discussed below The mesh sizes specified for the global or local mesh refinement apply to all types of geometry i e triangles wires cuboidal volume elements etc in the same manner This is not a principal restriction I
201. aves Creeping waves on curved surfaces e Cone tip diffraction Tip diffraction at the tip of a cone Uncoupled with moment method This item specifies whether the coupling from the UTD region to the MoM region should be considered This option should only be used when the UTD and MoM regions are not close together When no UT card is used the following default values apply Maz no of ray interactions 3 Write debug information to dbg unchecked Export UTD ray data for later viewing unchecked Select ray contributions includes GO direct and reflected rays shadowing Edge and wedge diffracted rays Corner diffraction terms Increasing the type and number of ray interactions increases accuracy but computation time as well The user should therefore make a compromise between the number of ray interactions and the ray contributions Choices made in this card should be made on physical considerations to get optimal use from the UTD formulation The following restrictions apply for the hybrid MoM UTD e no dielectric bodies or dielectric ground e only perfectly conducting flat polygonal plates or a single cylinder allowed in the UTD region e no UTD and PO at the same time December 2005 FEKO User s Manual 9 100 DESCRIPTION OF THE GEOMETRY CARDS 9 2 42 UZ card With this card a cylinder is created for the UTD region UZ Specify a UTD cylinder lt p si o Y s2J i sf s A yo The ang
202. ays with respect to the environment e g if the relative permittivity r of the cuboid material differs from the environ ment then this is a dielectric cuboid Old format with medium parameters Up to and including FEKO Suite 4 3 for cuboids the material parameters were specified directly at the QU card This is the old card format From FEKO Suite 5 0 onwards the concept of ME DI cards is used to define the material by name and to set the material parameters When checking this option the panel layout will change to the old format so that the material para meters can be entered depending then on the selection whether dielectric or magnetic cuboid FEKO then uses a compatibility mode and creates artificial media with names QU_MED_xx xx is an index It is not recommended to use the old card format for new models When working on old models and pressing F1 in EDITFEKO on an existing QU card the old format panel will be opened automatically EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 83 Dielectric bodies treated with the volume equivalence principle using cuboids cannot be used simultaneously with dielectric bodies treated with the surface equivalence principle or the FEM or with special Green s functions Example of QU card usage The dielectric cuboid shown in figure 9 37 is generated using a QU card Figure 9 37 Example for the QU card from demo_QU1 pre
203. bandwidth options are selected FEKO will also print a table giving the performance of the various nodes It is recommended that this is used during setup to ensure an optimum configuration It is possible to launch the job without including the local machine The fek input file must then be located on the first PC in the list and the out and bof output files are created on this PC both in the exactly same directory as the project directory on the local machine It is the user s responsibility to transfer the files between the local machine and the first machine in the list if these are not the same or one can also use remote parallel launching where FEKO does this copying explicitely see section 8 2 3 for details December 2005 FEKO User s Manual 8 4 THE FEKO SOLUTION KERNEL These checks are repeated each time FEKO calculates the solution so it may require a significant amount of time if the test file contains multiple frequencies One would not keep these options selected after the initial setup except for debugging purposes The user can also set the target priority of the FEKO run in this window Setting the priority below normal will allow the user to continue with other interactive work However all machines in the cluster operate at the speed of the slowest node so starting other CPU intensive jobs on one of the nodes in a cluster is generally not recommended After having configured the parallel FEKO version an
204. be required and should be set here FEKO_MPISTATISTICS This environment variable provides additional information about the performance of the parallel version of FEKO There are three options 1 Give a detailed report of the CPU and run times for the individual processes It is for example possible to determine how much time each process required during the computation of the array elements 2 Give as additional output the MFLOPS rate of each process without network communication time This is useful to determine the relative performance of nodes in a heterogeneous cluster 4 Give information about the network performance latency and bandwidth This is very useful when configuring parallel clusters The options can be added in a binary fashion for exam ple setting FEKO_MPISTATISTICS 5 will print both the run times and network performance FEKO_PARALLEL_DEBUG For parallel runs of FEKO under UNIX this environment variable can be set to 1 in order to see all the details and commands used in the parallel launching and machines file parsing etc This is helpful for troubleshooting errors December 2005 FEKO User s Manual 2 24 GENERAL COMMENTS FEKO_RSH When installing the parallel FEKO version on a UNIX cluster then communication between the nodes is required both at installation time checks on the remote nodes re mote copying of files remote execution of utilities etc but also when using FEKO remote launc
205. ber of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read The keyword RESONANCE or RESONANZ is used in the opt file to indicate that this keyword should be used The aim function is specified as fi Im Z with Z being the input impedance of the i block December 2005 FEKO User s Manual 11 22 THE OPTIMISER OPTFEKO Maximisation or minimisation of near fields This aim function enables one to maximise the electric or magnetic field strength in the near field This is particularly useful for a transmitting antenna that radiates constant power In addition any linear combination with arbitrary proportionality factors of the electrical and magnetic fields can be maximised or minimised by using negative values of the proportionality factors Aim function oP Aim 1 Select aim function Near fields y Weighting factor fi e EleciMag Linear Treatment for multiple blocks Averaging over the blocks Take maximum minimax principle Elec Mag field Components E Raon S Number of blocks Lines per block Linear combination Components EJH X Rho R z Electric Number of blocks Lines per block Constant Magnetic Number of blocks Lines per block Constant IV Include default comments Weighting factor This factor specifies the relative weight
206. ble to Ignore small features Small details are then ignored at a possible cost of accurate geometry representation This option also sometimes allows meshing faulty surfaces that cannot be meshed with the default settings Note that ignoring small features does not work for closed edges Such edges can however be broken in two by imprinting points see section 4 7 7 If Enable mesh smoothing is checked an additional smoothing algorithm is applied This will result in a better quality mesh but will obviously increase meshing time December 2005 FEKO User s Manual 4 38 WORKING IN CADFEKO Figure 4 20 Default top and optimised bottom mesh near the tip of a long narrow element Here the width of the strip falls within the small feature size For the optimised mesh the vertices on the long edges are aligned The sizes specified on the Create mesh dialog are used on all items which do not have a finer local mesh size see section 4 12 1 below Note that specifying a local mesh size on a region will also set that size on its bordering faces This only applies when the region mesh size is used i e when the region is meshed into tetrahedra An additional finer mesh size can of course be specified on these faces The minimum of all applicable mesh sizes is used thus local sizes that are larger than the global size are ignored Likewise setting a mesh size on a face also sets that size on its bounding edges If a finer mesh s
207. ble to edit geometry objects variables can be introduced after constructing the model While the geometry is fully parametric the mesh is not because storing expressions for mesh vertices would have severe implications on memory requirements In general operations working at the part level are fully parametric but operations that apply to individual elements are not When working with mesh elements most input fields still accept expressions For example just add 1 to a coordinate of a vertex to move it by one unit These expressions are then converted to values when the operation is executed Variables may be added by double clicking on the Variables entry in the tree or selecting Geometry Add variable from the main menu The first character of a variable name must be alphabetic a though z and A through Z or the underscore the remain ing characters may also be numeric 0 through 9 Variable names are case insensitive i e a and A are treated as the same character The Expression defines the value of the variable and may be a simple number such as 1 23 or a mathematical expression which may use round brackets the operators exponential notation other variables as well as the functions listed below December 2005 FEKO User s Manual 4 14 WORKING IN CADFEKO fmod fmod a b returns the remainder of the division a b sin trigonometric functions
208. btained For an optimisation where the SWR or VSWR should remain smaller than a certain value s this feature of specifying PIB can be used A penalty is added to the aim function if the SWR is larger than s but nothing is added for values smaller than s In order to compute the value T4B that must be specified in the opt file from the maximum standing wave ratio s use the relationship rB 20 log 20 log e g for a SWR limit of s 2 5 we obtain 3 7 36 dB Apart from the value of the aim function Z the real part and the imaginary part of the input impedance Z are written to the log file the latter only for the first block EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 21 Resonance This aim function is used to tune an antenna circuit resonator to resonance according to the criterion that the imaginary part of the input impedance should be zero Aim function Aim 4 Select aim function Resonance y Weighting factor fi ea for multiple blocks Averaging over the blocks Take maximum minimax principle Number of blocks IV Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions Num
209. can be written to the FEKO output file a Nastran format file an STL file or any combination thereof The name of the Nastran or STL file will be the same as the FEKO model but with a nas or stl extension Writing the geometry data to the output file Send to standard output may lead to huge output files If the field Nothing is selected no messages are sent to the stan dard output device usually the screen If the item Warnings errors progress messages is selected warnings errors and mes sages that indicate the program s progress are sent to the standard output device Switch normal geometry checking off If this item is checked then verification of the geom etry is switched off see the discussion below this table EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 23 edg options The edg file is used to store the connectivity information of the triangles The file can be stored in binary or ASCIT format Binary format is used to keep the file size small The edg file is read if it is present and created such that it may be read at a later run if not This is used to reduce the geometry set up computation time especially for big models on large parallel computers The ASCII formatted version of the edg file can be copied between platforms e g when preparing models on a PC and running FEKO on a workstation but the file can become quite large
210. card approximated by a staircase construction of cylinders and sections of a torus that resembles a cylinder EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 29 TO card Although the FO card is strictly only applicable to spherical and cylindrical surfaces it is often a good approximation on conical and toroidal surfaces It must be noted that the search for creeping rays on the Fock surface does not take into account multiple Fock regions i e one creeping ray can only exist in one Fock region Therefore when for instance modelling a sphere and using symmetry it is highly advisable to create part of the sphere then use the SY card to mirror it and only then use one FO card which applies to the whole sphere When using SY cards or also TG cards they do operate on already existing Fock regions defined above these cards and mirror them also or move them but with SY the problem just is that after the symmetry there exist then multiple Fock regions and the creeping rays along geodesic lines stop at the boundary of each Fock region December 2005 FEKO User s Manual 9 30 DESCRIPTION OF THE GEOMETRY CARDS 9 2 16 FP card With this card options related to the FEM Finite Element Method can be set FP FEM parameters J Decouple with moment method on order Second order C First order reduced accuracy Parameters Decouple with moment method Normally
211. card an impressed current source is specified similar to that of the AI card but with the AV card the end point makes electrical contact with a conducting surface as shown in figure 10 16 The current varies linearly between the value at the start point and that at the end point At the connection point special singular functions are used for the surface current density on the triangles to allow continuous current flow Parameters New source Add to sources AV Impressed current connected to triangle New source C Add to sources Specify end point coordinates below C Connectto closest triangle s vertex Start Amplitude A Phase deg x coordinate y coordinate z coordinate Radius of impressed current New excitation replaces all previous excitations Additional excitation is added to previous excitations Specify end point coordinates below The coordinates of the end point 72 are known and specified with the zx y z coordinate fields This point must coin cide with a corner point of one or more triangles Connect to closest triangle s vertex The coordinates of the end point 72 are not known In this case the a y z coordinate fields of the End point are not used FEKO searches through all the metallic triangles for the corner point that is closest to the start point 7 of the current element This is then the end po
212. card with multiple frequen cies is used This however does not always offer the flexibility which one may require for example to change the material parameters inside the loop Another example would be the use of a loop to create a complex geometry For completely general loops PREFEKO allows the construct for var start to end step delta Inext December 2005 FEKO User s Manual 7 8 THE PREPROCESSOR PREFEKO where a simple example would be Loop for the relative permittivity for eps_r 1 to 5 step 0 5 Set material parameters GF 0 eps_r 1 Compute fields etc FE End of loop Inext The syntax requirements of FOR NEXT loops are e The characters must be located in the first two columns of the line This is followed by a number of optional spaces and the keyword for it is not case sensitive so also FOR or For are accepted e The keyword for is followed by the name of the loop variable starting with The variable name is terminated by a space or the sign e Next follows an expression for the initial value of the loop a constant variable or formula see the example below e This is followed by the keyword to and the terminating value of the loop variable again a constant variable or formula e The default increment of the loop variable is 1 but it can be changed by using the keyword step followed from an expression Negative increments are allowed e The loop is term
213. ccount e If several of these current elements are used the total radiated power required to calculate for example the far field gain directivity can only be calculated ac curately if the mutual coupling between segments is taken into account Due to neglecting the point charges at the ends of the segments the coupling cannot be determined accurately If exact values of the radiated power are required it should be determined by integrating the far field see the FF card It should be noted that for example the computed near and far fields the actual field strength values the induced currents coupling factors and losses are computed correctly EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 31 10 2 14 AP card With this card a planar cylindrical or spherical aperture of measured or calculated field values is converted into an equivalent array of electric and magnetic dipoles The card is processed by PREFEKO and replaced by A5 and A6 cards in the fek file AP Define an aperture field as source New source Add to sources Load field data from efe hfe file Load field data from ASCII text file C The field data follows in the pre input file Electric field on planar Cartesian aperture Magnetic field on planar Cartesian aperture C Both fields on a planar Cartesian aperture Both fields on a cylindrical aperture Both fields on
214. ce If the splitter between the floating and node locked licences is dragged upwards the area used for floating licences can be reduced or even removed completely Drag it downward to show the floating licence area again A FEKO licence manager olx Info Server Help IV Default licence file TF Local mode ap Update Preferred licence Clear license secfeko_server dat Browse Por 3 ey Floating licence no Used by Expiry date Suite Pricing category Memory limit Parallel bm Floating Node locked licence no Hostname Expiry date Suite Pricing category Memory limit Parallel El Node locked Dongle 2005 10 30 5 0 Silver Unlimited Sequential licence E H Machine code Components CableMod PCBMod on Out of core on Only geometry check off Green s functions on ipt pyt 2005 09 30 5 0 Silver Unlimited 16 Figure 3 1 The licence manager with a typical node locked licence December 2005 FEKO User s Manual 3 2 THE LICENCE MANAGER The licence manager will by default open the file FEKO_HOME license secfeko bat which is also used by all FEKO components The user may however also uncheck Default licence file and browse for an alternative file for example to check the information in a new secfeko dat file before replacing an existing licence file If Local mode is checked floating licences are displayed without connecting to the server The licence for the current host is shown in green
215. ce formulation in the MoM to model dielectric bodies then each source acts as incident field only in the medium where this source is located Coordinate system In this dialog the coordinate system for the calculation of the requested fields is specified If Specified points is selected here additional dialogs for the Num ber of field points and the Coordinates are shown One must then enter the coordinates of each point For all other cases additional dialogs for Starting values Incre ment and No of points are shown each with three values for the three components of the respective coordinate system Use old output format If this item is checked the old format of the near field is used in the out output file This should only be used for compatibility with third party post processors POSTFEKO cannot extract SAR values from near fields in this format Note that all coordinates are in metres and all angles in degrees Scaling with the SF card is only applicable when the option Modify all dimension related values is selected default behaviour and highly recommended in the SF card in this case coordinates must be in metre after scaling Potentials cannot be computed with the FE card if UTD or PO is used Also only the free space Green s function is supported not the Green s functions for layered spheres or multilayered planar media If the total potentials are requested the potentials for the sources are added Thes
216. ce of the toroidal segment It must be in the plane S2 S1 83 The angle vy The angle of rotation around the axis S1 52 The angle a The angle of rotation around the axis of the toroid see the figure displayed in the card Max edge length p direction The maximum edge length along the curved edge in the y direction in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Max edge length a direction The maximum edge length along the curved edge in the a direction in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Normal vector directed The triangles can be created such that the normal vectors point Outward outward away the ring axis of the toroid or Inward Scale second half axis If this parameter is empty or is set to 1 a toroid with a circular cross section is created If set to 2 an elliptical toroid is cre ated by distorting the entire geometry along the second half axis EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 95 orthogonal to the axis S1 S3 with the factor 2 where a is the distance S1 83 It is recommended to generate toroids where the elliptical cross section has extremely small or extremely large ax ial ratios with a CAD system such as FEMAP as the distortion formulation used in PREFEKO may fail in these cases A complete toroid is obtained b
217. ce position before the SP card these loads will be overwritten Also when execution continues after processing the SP card these loads will still be present The original amplitudes of the excitations will however be restored December 2005 FEKO User s Manual 10 118 DESCRIPTION OF THE CONTROL CARDS 10 2 44 TL card This card is used to connect a non radiating transmission line between two segments TL Non radiating transmission line C Remove all existing transmission lines New transmission line C Add to existing transmission lines I Cross input and output ports Input port Select label C Specify position Output port C Select label Specify position J Calculate length from position Transmission line length m FY Losses dB m a Real part of Zo Ohrn rs Imaginary part of Zo Ohm rs Real part of shunt Y at port 1 tt Imaginary part of shunt Y at port 1 iY Real part of shunt Y at port 2 Po Imaginary part of shunt Y at port 2 poo Input port Output port Segment label x Parameters Remove all existing transmission lines If checked all previously defined transmission lines are deleted All the other input parameters are ignored New transmission line Defines a new transmission line all previously defined transmis sion lines are replaced Add to existing transmission lines An additional transmission line is defined Cross input and out
218. cember 2005 FEKO User s Manual 9 66 DESCRIPTION OF THE GEOMETRY CARDS All the wire segments that follow this card are assigned the properties of the medium in which they are found Triangles are treated differently it depends upon whether they are metallic triangles or triangles on the boundary of a dielectric object Here the properties of the media are assigned to the respective sides All triangles and segments before a ME card represent metallic structures in free space This is also the case when an input file does not have a ME card When using the FEM and meshing structures into tetrahedral elements or when using the volume equivalence principle in connection with the MoM MLFMM and meshing into cuboidal volume elements then the selection for type of triangle is not relevant The specified medium will be used medium A if there are multiple media input fields The medium name can be an arbitrary string using the characters A Z the digits 0 9 or also the underscore _ See section 2 3 for details also with respect to ranges etc the discussion there for labels applies in a similar manner also to media Note that the outer medium must always be medium 0 the number zero The use of the ME card to create a simple dielectric sphere is shown in example_04 see the Examples Guide note that the normal vectors of the sphere point outwards from medium 1 the dielectric to medium 0 free space In addition example_23 shows
219. ch could be larger than the average amplitude value SAR specific absorption ratio is calculated from where is the conductivity and p the medium density EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 9 4 The View near field iso surfaces page draws an iso surface of the near field This effectively connects all positions where the field value match the value specified in the Iso value slider Note that the scale limits controls the extent and hence the sensitivity of the Iso value slider 5 The Show spatial peak SAR page displayes SAR specific absorption rate as cal culated using the SA card see section 10 2 41 It also displays the cube at the position of maximum SAR when applicable 6 The Show UTD rays page controls the visibility of UTD rays The rays are not stored by default as the output file can quickly become very big It must be explicitly activated at the UT card see section 9 2 41 The Select tab is used to select specific rays Each ray group includes all rays that start and end at the same point Ray type limits the display to certain types of rays Finally the Field type facilitates selecting rays obtained during specific calculations it is for example possible to hide all rays calculated when determining the coupling between the UTD and MoM regions The Far field crop slide bar can be used to restrict far field points to within the geometry display POSTFEKO incl
220. cial Green s function of a planar substrate maxnqua The maximum number of dielectric cuboids maxnseg The maximum number of segments maxntetra The maximum number of tetrahedral volume elements for a FEM solution maxnzeile The maximum number of basis functions in the moment method area maxpoka The maximum number of bordering edges to the PO area EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 19 maxpokl The maximum number of wedges in the PO area maxpolyf The maximum number of polygonal surfaces that can be used to represent a body in the UTD region maxpolyp The maximum number of corner points allowed for a polygonal plate maxpovs The maximum number of label to label visibility specifications set by VS cards a card with a range sets a number of entries equal to the size of the range maxsklayer The maximum number of layers at an SK card maxtlcards The maximum number of TL cards maxutdzyl The maximum number of cylinders in the UTD region nmat The memory size that may be allocated for the matrix of the system of linear equations For nmat 0 the necessary amount will be al located dynamically The allocation is not specified in Bytes but in terms of the number of type DOUBLE COMPLEX numbers These require 16 Bytes each For example 400 MByte is specified by set ting nmat 400 1024 1024 16 The same effect can be achieved by setting the variable maxalloc such
221. cond one is not Metallic structures can have an arbitrary orientation horizontal vertical and also diag onal They can lie at an arbitrary position in one or more layers and can lie directly on the border of two layers e g on the surface of a substrate The only restriction is that no metallic segment or triangle may cross a boundary between layers i e it must lie completely within one layer or at the boundary between layers If for example a metallic wire penetrates a multilayer substrate the segmentation must be such that there is a node on each interface between layers See example_31 in the Examples Guide The following is not possible with this Green s function e dielectric ground BO Card e hybrid MoM PO method hybrid MoM UTD method hybrid MoM FEM method dielectric bodies with the surface or volume equivalence principle December 2005 FEKO User s Manual 10 92 DESCRIPTION OF THE CONTROL CARDS 10 2 31 L4 card This card can be used to add a load between a metallic triangle and the ground plane for the planar multilayer Green s function without having the requirement to model a vertical current element analogous to the A4 excitation card L4 Load a coaxial attachment point Define a load ata coaxial attachment point Remove all L4 type loads previously defined Select element Setload position Apply load to last element with label J Transform impedance to g
222. ct other spec 1 2 0000e 01 8 0000e 01 7 1538e 00 0 0000e 00 1 7 1538e 00 2 2 8693e 01 8 0776e 01 7 0386e 00 0 0000e 00 1 7 0386e 00 3 2 2329e 01 8 2898e 01 7 0007e 00 0 0000e 00 1 7 0007e 00 4 2 6364e 01 7 7879e 01 7 0176e 00 0 0000e 00 1 7 0176e 00 EM Software 4 Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 29 oono 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 DADAS 000 JI0wWN OO be br pr EEE Distance a A oO oO ao o D N 60 40 20 0 Angle a in Deg 20 Gain in dB max Figure 11 2 Gain as a function of the optimisation parameters 7671e 01 1307e 01 3636e 01 5653e 01 2471e 01 4489e 01 0142e 01 9600e 00 1953e 00 6133e 00 7780e 00 1247e 00 1333e 00 5423e 00 5510e 00 3777e 00 9686e 00 1953e 00 2043e 00 7867e 00 4643e 00 6688e 00 1732e 00 0865e 00 NNNNNNNANNNANNONNNNNNONONN 7102e 01 9224e 01 2121e 01 9612e 01 0672e 01 8163e 01 71775e 01 8835e 01 7386e 01 8447e 01 9896e 01 0284e 01 9029e 01 9560e 01 8305e 01 8111e 01 7581e 01 7386e 01 71917e 01 8641e 01 8208e 01 8473e 01 7846e 01 7749e 01 1202e 00 2145e 00 0740e 00 1914e 00 1658e 00 1970e 00 2171e 00 2225e 00 2218e 00 2150e 00 1728e 00 1769e 00 2205e 00 2053e 00 2270e 00 2282e 00 2214e 00 2218e 00 2255e 00 2207e 00 2281e 00 2268e 00 226
223. ct htm Alternatively for technical questions please send email to feko_support emssusa com for North America feko_support emss de for Europe feko_support emss co za for all other regions or for activation codes and licence queries to feko_license emssusa com for North America feko _license emss de for Europe feko_license emss co za for all other regions December 2005 FEKO User s Manual GENERAL COMMENTS 2 1 2 General comments 2 1 Structure of the input file The main FEKO kernel is using a card based pre file as input similar to the thin wire MoM code NEC Such an input file consists of various cards high level commands which can be categorised into geometry cards and control cards The geometry and the field parameters to be calculated are specified using these cards Ons of these cards allows importing meshed geometry This is used to integrate CADFEKO models into the final FEKO input file Certain geometric cards are interpreted and filtered out by the preprocessor PREFEKO and translated into other cards Normally users are advised to use EDITFEKO then there are panels where the various settings can be made and also the format of how each card is written back to the main file edit window will be correct The card format is described here mainly for users wanting to create a FEKO input file automatically by some other code FEKO supports two different formats for cards the colon separated and the column based fo
224. ct the creation of a new opt file This will bring up a blank window on the right and a panel on the left with a single Edit button Press this button to open the dialog panel for the optimisation parameters Note that this edit mode has a lot in common with editing pre files If an existing opt file is open in the editor pressing F1 in a section of the file will open the editing panels for that section 11 2 1 The optimising toolbar At the top of the optimisation editing panels the optimising toolbar is shown This toolbar is used to switch between the panels that control the four aspects of optimisation EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 3 The functions of the buttons are 1 Show the parameter control panel This panel is used to specify which parameters must be optimised 2 Show the penalty function control panel This panel is used to specify penalty functions for variables that exceed given boundaries 3 Show the optimisation function control panel This panel is used to choose the optimisation method that OPTFEKO must use as well as its parameters 4 Show the aim function control panel This panel is used to specify the goal s of the optimisation function 11 2 2 Definition of optimisation parameters The parameters to optimise are controlled using this panel These parameters correspond to variables in the pre file Parameters
225. ction of incidence is to be examined is incremented by this value for each new angle of incidence Ellipticity This field is only applicable when elliptical rotation is selected under Polarisation above and gives the ellipticity of the rotating polarisation It must be larger than 0 linear polarisation and smaller or equal to 1 circular polarisation The direction of incidence Bo is specified by the incidence angles Y and p The polarisation angle y measured from the negative of the spherical coordinate system unit vector V and the field strength vector Ep is defined as indicated in the figure in the card above The electric field strength of the incident field is then given by E r Eo ju Eo x fo e i where v is the ellipticity For linear polarisation it is 0 for right hand rotating it is equal to the value in the Ellipticity field for left hand rotating it is the negative of the value in the Ellipticity field The incident magnetic field is given by Si ay i E H 7 Zr x Ej with Zp the wave impedance in the surrounding free space medium It should be noted that the incident power density which is required for example for RCS computations is given by 2 Us gt 1 5 Si Fol 1 It is possible to vary the direction of incidence This is particularly useful when e g determining the monostatic radar cross section The two parameters Initial Y value and Initial p value indicate the direction of
226. ctric layers A special Green s function is available see the GF card section 10 2 30 e Planar multilayer substrate with or without a perfect conducting ground plane A special Green s function is available see the GF card section 10 2 30 December 2005 FEKO User s Manual 2 16 GENERAL COMMENTS The entered structures e g metallic wires and surfaces do not necessarily have to be embedded in free space The EG card section 9 2 12 or DI card section 10 2 25 or also the GF card section 10 2 30 can be used to specify the material parameters of the surrounding medium 2 6 Dynamic memory management 2 6 1 Telling FEKO how much memory can be used FEKO has the ability to manage the memory dynamically i e the memory required for the geometry data and matrix elements etc is determined and allocated at run time When FEKO tries to allocate memory in principle the operating system offers a certain address space which might either be physically installed memory i e RAM but also virtual memory system swap space swapped to the hard disk If FEKO starts to swap using virtual memory then the whole solution process can be slowed down quite significantly and this is not recommended FEKO also has an out of core solution which uses the data on disk in a much more efficient way The out of core technique is also used of course if the problem requires more memory than is available in both RAM and virtual memory Fo
227. d e The coefficients are conjugate complex i e GRASP assumes an e time depen dency December 2005 FEKO User s Manual 10 82 DESCRIPTION OF THE CONTROL CARDS e The index m is exchanged with m since in FEKO the dependency is defined differently than in GRASP e versus e These conversions are done automatically by FEKO when exporting the SWE file so that this can readily be imported into GRASP EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 83 10 2 29 FR card This card sets the frequency frequencies in Hz at which the solution will be obtained FR Set the frequency C Single frequency Discrete frequency points Continuous data adaptive sampling Max number of sample points For Cablemod CM card use only Number of discrete frequencies for isd file Mi Frequency stepping e Linear C Multiplicative Frequency scale Linear Multiplicative Specify by Frequency increment Ending frequency Starting frequency Hz Min frequency stepping Hz Ending frequency Hz The solution can be done for a single frequency a loop of discrete frequencies linear or multiplicative stepping or a continuous solution in a given frequency band with adaptive frequency interpolation For a continuous solution only one FR card is allowed Parameters Single frequency Only a
228. d 10 58 check for updates 5 5 circular arcs 4 21 circular cone 9 54 circular dependencies 4 13 circular disc 9 59 circular hole 9 72 CL card 9 14 clash 4 33 clear model 4 5 click mouse 4 5 CM card 10 62 CN card 9 16 CO card 10 63 coarse segmentation 9 52 coating of wires 10 63 coaxial attachment approximation 10 16 coil 9 31 collapse tree items 4 11 colour 4 6 dielectrics 4 31 colour by label 6 5 colour by medium 6 5 command line parameters 4 46 6 1 11 comments 4 48 9 3 10 5 PS 10 103 complexity reducing 4 29 PW 10 105 CONCEPT file 9 47 SK 10 111 cones 4 18 9 54 SP 10 117 connection points TL 10 118 definition 2 2 control panel constructing solids 4 31 POSTFEKO 6 5 contact us 1 3 copy 4 24 4 30 continuous frequency 6 10 6 11 geometry 9 91 control cards 2 1 10 1 multiple 4 24 10 5 copyright 15 1 AO 10 9 coupling 10 117 A1 10 12 transmission line 10 23 10 62 A2 10 13 create A3 10 14 geometry 4 16 A4 10 16 solid regions 4 31 A5 10 18 cuboidal volume elements 9 17 9 20 9 82 A6 10 19 cuboids 4 18 9 17 9 81 9 82 A7 10 21 definition 2 3 AC 10 23 current sources AE 10 26 line segment 10 23 10 29 10 49 AI 10 29 currents AP 10 31 calculation request 10 101 AR 10 38 display 6 8 AS 10 43 curves 4 31 AV 10 49 arc 9 14 AW 10 51 creating surfaces 4 26 BO 10 54 cutplanes 4 10 6 7 CF 10 56 and selection 4 35 CG 10 58 through solids 4 10
229. d IN cards such that dimensions may be entered in different units and scaled to metres The principal structure of the input file is shown below Comments at the start of the input file Cards that define the geometry EG End of the geometry control cards that define the excitation and indicate which field quantities shall be calculated EN End of the input file Chapter 9 gives an overview of the geometric cards with detailed descriptions of the individual cards also how to import external meshes or CADFEKO models using the IN card Similarly Chapter 10 gives an overview and description of the control cards 2 2 Modelling and meshing guidelines 2 2 1 Definitions and terms Conducting surfaces are subdivided into triangles and wires into segments For di electrics there are a number of possibilities see the discussion Dielectric Solids in section 2 5 Using the surface current method the surface of the dielectric solid is also sub divided into triangles whereas with the volume current method the solid is subdivided into cuboids For the FEM the mesh is based on tetrahedral volume elements Given below are a number of definitions that are used frequently in this manual Segment A short section of a wire short in comparison with the wavelength Node The point where two segments are joined is called a node One basis function is assigned to each node Edge The common line between two adjacent triangles If th
230. d after having set any possible special options the parallel FEKO version can be run To do this click in the Run menu on Parallel FEKO execution so that this gets checked Then any subsequent runs of the FEKO solver until this gets un checked again will use the parallel version of FEKO From the command line e g on a UNIX workstation the parallel FEKO version is started with runfeko example_08 np x where the parameter x following np gives the required number of processes In addition to the arguments listed in section 8 2 1 the parallel version accepts the following optional parameters np x Start the parallel FEKO version with x processes machines file machname The file machname is the machines file with the node names and the number of CPUs see below mpi options All options following this if another xxx options parameter is used all arguments before the second xxx options parameter are passed to the MPI launcher e g mpirun or mpiexec The number of processes to start on each available host is specified in a so called machines file with the general syntax Hostname Number of processes using a new line for each host For example if the user has two hosts with names host1 and host2 this is the output of the UNIX command hostname and 4 and 8 processors respectively the machines file will be host1 4 host2 8 With this machines file the example with 6 processes given above will run with 4 processe
231. d is used If this item is checked a tapered wire radius can be set Nor mally the wire radius is set with the IP card Checking this item overrides this radius for the current helix without affecting the default for later segments The radius is in m and is affected by the SF card scaling factor The segments connecting to the axis are not tapered and have radii corresponding to the start point and end point respectively December 2005 FEKO User s Manual 9 31 9 32 DESCRIPTION OF THE GEOMETRY CARDS Radius at start The radius of the wire at the start of the coil Radius at end The radius of the wire at the end point of the coil Scale second half axis If this parameter is empty or is set to 1 a helix with a circular cross section is created If set to 2 a helix with an elliptical cross section is created Here 2 gives the ratio of the two half axes where a is the distance S1 53 It is recommended to generate elliptical helices with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases Quite often modelling the geometry of the coil requires shorter segments than those used for straight wires Thus the maximum segment length specified by the IP card can be overridden along the arc by setting Maximum segment length The windings are generated between the two points S1 and S2 that lie on the axis The radius of the coil is defined b
232. d side of this table will contain the names of all the parameters The two columns contain the over and under estimated penalty factors as described below EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 5 To ensure that the optimisation parameter x stays within the bounds yjn and Zmax a penalty function can be added to the aim function The penalty function P is defined by the equation 10 P min for t lt Lmin Umax Lmin Ps 0 for Lmin lt TS Tmax 10 P max _ for 2 gt Lar Tmax Tmin The two parameters P and P define the value of the penalty function when overestimat ing the allowable range by 10 When the penalty function is added to the aim function it must be ensured that they both are of the same dimension The penalty function is defined with the keyword PENALTYFUNKTION or PENALTY_FUNCTION In the rows that follow the optimisation parameters P and P are specified If no penalty functions are to be assigned at all then the whole section can be left out 11 2 4 Definition of the optimisation process During optimisation new values for the parameters are chosen by a function known as the optimisation function This panel is used to choose the optimisation function and its parameters Each function has different parameters that must be set and therefore each one is discussed separately below Discrete points This method is strictly speaking not an optimisati
233. dex 0 In connection with the UTD only outward propagating modes are allowed they have a well defined source point while inward propagating modes are not supported neither a source point nor an incidence direction can be assigned to such modes When computing the far field with the FF card then outward propagating modes are included normally which is important when synthesising antenna patterns by means of spherical modes However for inward propagating modes the far field limit for R oo EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 47 of the field strength with the factor eib R R split off does not exist similar to the non existent far field for an incident plane wave Thus such inward propagating modes are excluded from any far field computation This is not a problem since normally inward propagating modes are applied when computing the generalised antenna scattering matrix i e the response of a receiving antenna to some incident mode Then one looks at these quantities e Induced voltage or power at the antenna terminals for the network ports i e no far field computation e Field scattered back and decomposition of this field into spherical modes far field ports Here one needs the far field computation but similar to an RCS computation with an incident plane wave only the scattered far field is of interest which can be obtained from the FF card without prob
234. ding of the file structure is necessary December 2005 FEKO User s Manual 11 2 THE OPTIMISER OPTFEKO This file consists of three or four sections e Assignment of optimisation parameters minimum and maximum values e Optional assignment of the penalty function e Optimisation parameters e g step size final value e One or more aim functions with the required parameters In the opt file blank and or comment lines starting with are allowed between the sections but they are not allowed to appear in the sections themselves The parameters are space delimited i e they are separated by spaces and can be placed in any column but they must be entered in the correct order The keywords used in the opt file exist in both German and English for example RASTERSUCHE and GRID_SEARCH OPTFEKO will recognise keywords in either language independent of the language selected by the environment variable FEKOLANG 11 2 Using EDITFEKO to create a opt file The EDITFEKO GUL is used to control the creation of the opt file To learn more about launching and using EDITFEKO consult Chapter 5 The format and creation of the pre file is discussed in this and other chapters All the functionality normally available in PREFEKO files is available when optimising Only the application of EDITFEKO to editing opt files is discussed in this chapter In order to use EDITFEKO to edit this file simply open the file if it exists or sele
235. ditioner which can be used in connection with the MLFMM for parallel MLFMM runs this is the only supported pre conditioner Options for the BCG This applies to the Biconjugate Gradient Method Options are e Fletcher s method e Jacob s method e Fletcher s method pre iteration using Fletcher s method e Fletcher s method pre iteration using Jacobs method e Jabobs method pre iteration using Fletcher s method EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 61 Block size The block size to be used for LU decomposition with LAPACK as well as for the Block Jacobi preconditioning When nothing is specified i e the input field is left empty then appropriate stan dard values are used for LAPACK and the block preconditioners Threshold value for ILUT This is the thresholding value used for the FEM in connection with the ILUT preconditioners Fill in level per row This is used by the MLFMM or FEM during the iterative matrix solution in connection with incomplete LU preconditioners Stabilisation factor FEM This applies only to the incomplete LU preconditioners of the FEM and can be used to get better convergence for the FEM in critical cases the value range is between 0 and 1 Save read preconditioner For the incomplete LU preconditioners used with the FEM one has here the option to save run time by computing the precon ditioner only once and write to
236. e The newly created triangles can be moved into an existing label Select all the elements of the existing label as well as all the new elements If the elements are selected by label click the Select mesh element button to convert the selection to individual elements Now right click on the selected elements and select Rename This will merge all the selected elements to one label All the labels that become empty are automatically removed and these names become available for the new label 4 13 11 Reversing normals Some features in FEKO make use of the normal vectors of elements For example di electrics are specified by giving the medium on each side of the bordering triangles For EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 45 this purpose the normal side of a triangle or polygon is defined as the side towards which the normal vector is pointing If the start point of the normal vector is located on the triangle the normal side is the one closest to the arrowhead In CADFEKO the normal sides of mesh elements are coloured blue while the backs are brown Back x Normal side Figure 4 23 The normal and back sides of a triangle When the selection contains triangles or mesh polygons or labels or parts that contain such elements selecting Mesh Reverse normals will invert the normals of all the selected triangles polygons Normal vectors can be shown explicitly per 3D view
237. e print and print_to_out commands accepts multiple arguments separated by commas For example llprint 2 b 2 b 1 if fa lt 2 b then print The value of a is too small a exiting now I exit t endif will print a warning and exit if the variable a is smaller than two times variable b The line print_to_out This run was done with b b will print the value of b to the out file at the position where it appears in the pre file December 2005 FEKO User s Manual THE FEKO SOLUTION KERNEL 8 1 8 The FEKO solution kernel 8 1 Introduction The program FEKO does the actual field calculation Input and output are done using files The program indicates on screen how far the calculation has progressed 8 2 Running the FEKO kernel 8 2 1 Running the sequential version Normally users are advised to run the FEKO kernel directly from the GUI components CADFEKO EDITFEKO or POSTFEKO Once a session or model has been loaded the sequential FEKO solver can be started from the Run menu there select FEKO as a shortcut key A1t 4 can be used Note that running the FEKO kernel will also automat ically execute the pre processor PREFEKO if the fek file does not yet exist or if the corresponding pre or cfm files are newer than the fek file When the FEKO kernel is not executed from within the GUI it can be started in a command window on a Windows PC or a shell in UNIX by executing the
238. e The mesh sizes are in m and are scaled by the SF card Mesh size along side b Edge S2 83 Mesh size along side c Edge S3 S1 Mesh size along side a Edge S1 82 The direction of the normal vector 7 of the subdivided triangles is determined by the right hand rule through all the corners This direction is only important when used with the Physical Optics PO card or with dielectrics ME card or for the CFTE CF card EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 11 Examples of BT card usage The meshes shown in figures 9 8 and 9 9 were created with BT cards using uniform meshing and non uniform meshing respectively Figure 9 8 Example of a BT card from demo_BT1 pre Figure 9 9 Example of a BT card with non uniform meshing from demo_BT2 pre December 2005 FEKO User s Manual 9 12 DESCRIPTION OF THE GEOMETRY CARDS 9 2 6 CB card This card is used to change or reassign the labels assigned to points segments triangles cuboids polygons tetrahedral elements etc CB Change already assigned labels Specify old new label here C Read list of old new labels from file Old label New label Parameters Specify old new label here This selection allows to specify an old label and a new label in the corresponding input fields Read list of old new labels from file This selection allows to read a list of old new label pairs fro
239. e all the single edges in parallel The LE card can be combined with the AE card to specify both an impedance and a voltage source over the edge Parameters Load edge between regions with two labels The edge between two labeled regions is loaded with a complex impedance The following parameters apply when this item is checked e Label of triangles on one side of edge The label on the first edge of the triangle e Label on second side of edge The label of the second edge of the triangle Label I Label I Load impedance Z R jX Figure 10 24 Application of the LE card December 2005 FEKO User s Manual 10 96 DESCRIPTION OF THE CONTROL CARDS Load an edge connected to ground UTD Load the triangles with a specified label that are connected to a UTD surface or to a PEC ground plane as spec ified with a BO or GF card The following parameters apply when this item is checked e Labels of triangles connected to ground The labels of the triangle that are connected to the ground Load microstrip edge between two points This is a special microstrip port load The load is placed on all edges on the line between two points previously specified with DP cards entered into the dialog below A GF card with a conducting ground plane must be present The following parameters apply when this item is checked e Start point of edge The start point not label of the edge e End point of edge The end point no
240. e may be defined as planes of symmetry There are three different types of symmetry They are described below 2 4 1 Geometric symmetry With this type of symmetry the geometry of the modelled solid or part of the solid is symmetric about one or more coordinate planes The interaction between any two basis functions must be the same as that between their symmetrical counterparts Everything which affects this must be symmetrical i e loading losses Green s functions etc The source however is not symmetric thus a symmetric current distribution does not exist This asymmetric current distribution leads to asymmetric electric and magnetic fields The body of a truck with an antenna placed at the front left hand side will be used as an example In the input file half of the body is constructed either the left or right side EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 11 The other half is then created with the SY command Finally the antenna is placed in the correct position on one side A rectangular metallic plate illuminated by an electromagnetic wave from a direction outside the principle planes is another example In this case a quarter of the plate is constructed and the rest is created using the SY card section 9 2 37 with geometric mirroring around two coordinate planes Geometric symmetry does not reduce the number of unknown coefficients in the current basis functions Therefore th
241. e processed IN Include an external file Import NASTRAN file y Y Include segments Y Include quadrangles IV Include triangles F Include node points F Include only node points for imported triangles and or wires File name y O El Include all items C Include only items with single label layer C Include items with range of labels layers NASTRAN properties convert to FEKO labels nclude structures with property Up to property Scale factor NASTRAN does not support polygonal plates but all other parameters in the general section of the IN card above apply The label selection uses the NASTRAN properties which are converted to FEKO labels As when importing FEMAP neutral files the wire radius must be set with the IP card preceding the IN card and an ME card must be used when specifying dielectric surfaces in the same way as when the IN card is not present Since grid points do not have an associated property points are imported irrespective of their label but they may be limited to those used for the imported geometry The user can also import points from the NASTRAN file The points defined in the NASTRAN file will then be available in PREFEKO as points as if they were defined by DP cards of the form Nxxx where xxx is the index of the grid point This may be used for example to attach additional structures to the geometry In addition the coordinate values of the point are a
242. e sharp resonances If left empty the default is 1 0E 4 Ending frequency Starting frequency If a discrete loop with more that one frequency is required then either the frequency increment or the ending frequency must be specified but not both If the end frequency is specified the frequency increment is calculated from e for a linear frequency scale additive increments A Af i Neal e for a multiplicative frequency scale multiplicative increments 1 A fac 2 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 85 where Ay is the frequency increment linear stepping fac the increment factor multi plicative stepping f the start frequency f2 the ending frequency and Ny the number of frequencies When writing results at discrete frequencies to a isd file the frequency increment when a linear frequency scale is used is calculated similar to the case for Af as shown above If more than one frequency is to be examined then all the control cards up to the next FR card or EN card will be read into a buffer and are executed for each frequency More information can be found in section 10 1 December 2005 FEKO User s Manual 10 86 DESCRIPTION OF THE CONTROL CARDS 10 2 30 GF card With this card the Green s function may be selected The Green s function relates the fields in space to the sources present The propagation space is usually free s
243. e to be calculated Figure 12 7 Cube with side lengths of 1m The input file cube pre is reproduced below The files are located in the examples utils timefeko subdirectory of the FEKO installation TIMEFEKO example pre file A metallic cube with side lengths 1m Only 1 8 of the cube is generated explicitly the rest of the cube is generated by means of symmetry Normally TIMEFEKO will automatically insert the correct required frequency value Use the following construct so that this value used by TIMEFEKO will not be overwritten but we can still display the geometry in WinFEKO 11if not defined freq then freq 100 0e6 lendif Define some constants ta 1 side length of the cube ttedgelen a 5 max edge length for the triangular patches Set the segmentation parameters IP edgelen December 2005 FEKO User s Manual 12 10 THE PROGRAM TIMEFEKO Define the points DP DP DP DP DP DP DP LA BP LA BP BP Ak SY CB SY ek EG K FR AO x 0s FF kk EN Pi a 2 0 0 P2 a 2 a 2 0 P3 a 2 a 2 tta 2 P4 a 2 0 tta 2 P5 0 0 a 2 P6 0 a 2 tta 2 P7 0 a 2 0 Create one eigth of the cube use label 1 for the front plate and label 0 for the rest 1 Pi P2 P3 P4 0 P3 P4 P5 P6 P2 P3 P6 P7 Mirror around to coordinate planes so that label for front plate remains 1
244. e IX number x m y m z m magn phase 1 2 25000E 00 0 00000E 00 6 67500E 01 0 000E 00 0 00 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 9 2 2 25000E 00 0 00000E 00 5 02500E 01 0 000E 00 0 00 3 2 25000E 00 0 00000E 00 3 37500E 01 0 000E 00 0 00 IY IZ magn phase magn phase 0 000E 00 0 00 2 208E 03 145 51 0 000E 00 0 00 6 118E 03 146 21 0 000E 00 0 00 9 000E 03 147 38 With the associated charge VALUES OF THE LINE CHARGE DENSITY ON SEGMENTS in As m Segment Q number magn phase 1 4 26233E 11 55 514 2 3 28910E 11 58 02 3 2 28537E 11 62 48 For every voltage source the current at the feed point is determined and thus the im pedance The following is the result DATA OF THE VOLTAGE SOURCE NO 1 real part imag part magn phase Current in A 1 0888E 02 4 4405E 03 1 1759E 02 22 19 Admitt in A V 1 0888E 02 4 4405E 03 1 1759E 02 22 19 Impedance in Ohm 7 8747E 01 3 2116E 01 8 5044E 01 22 19 Power in Watt 5 44395E 03 14 4 Finite conductivity Firstly the block with the set of characteristics for the single labels is displayed DATA OF LABELS Label 2 DOSKIN 3 DOLAST 0 Triangle thickness 5 00000E 03 m Sigma 1 000E 05 S m Mue_r 1 000E 00 Penetration depth of the skin effect 1 59210E 04 m All segments and triangles without a listed label are perfectly DOCOVR 0 tan delta_mu 0 000E 00 conducting December 2005 FEKO User s Manual 14 10
245. e are not available for a plane wave AO card or an impressed radiation pattern AR card and FEKO will give an error For a magnetic dipole A6 card the electric ring current model yields A and the magnetic current yields F and V w all the other potentials are zero If one requests efe and or hfe files with the DA card then A and V y are written to the efe file while F and V y are written to the hfe file If a ground plane is used a calculation of the near fields in the ground plane is not possible The observation points in the area z lt 0 are not taken into account It should be noted that the coordinates may have an offset OF card Thus the near field on the surface of a sphere can be calculated with the centre of the sphere not being located at the origin of the coordinate system The different Coordinate systems are described on the following pages EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 73 e Cartesian coordinates 2 Y zZ Pr x y Figure 10 17 Field calculation in the Cartesian coordinate system Observation Point A II e 8 Unit vectors of the coordinate system 1 0 0 gt II S amp S II me gt II December 2005 FEKO User s Manual 10 74 DESCRIPTION OF THE CONTROL CARDS e Cylindrical coordinates around z axis r y z Zz A x y Figure 10 18 Field calculation in the Cylindrical coordinate system Obs
246. e magnetic in nature i e the relative permeability ur of the coating must be the same as that of the surrounding medium December 2005 FEKO User s Manual 10 64 DESCRIPTION OF THE CONTROL CARDS Electrically thin surface coating This option adds multilayer dielectric magnetic coatings to the surface triangles with the specified label The layers may have different permittivity and permeability but the total coating must be electrically i e relative to the wavelength in the coating as well as geometrically thin see the next item Dielectric magnetic surface coating This option adds electrically thick multilayer dielec tric magnetic coatings to the surface triangles with the specified label Here it is only required that the total coating must be geo metrically thin i e it must be thin relative to the triangle size and thus also to the free space wavelength as well as the radius of curvature of the surface This option may only be applied to elements treated with PO Number of layers This field is only applicable for surface coatings Note that the layers are symmetric around the conductor and that the layer assigned the highest number is closest to the conductor Thickness of For surface coatings the thickness hn of each respective layer for wire coatings this is the radius of the coating less the radius o of the wire core This value is in m and is scaled by the SF card Relative permeability Relative
247. e spin sweep or loft operations or as free standing conducting wires In addition to the general curves resulting from intersections between faces of shell bodies CADFEKO supports a number of simple primitives These include single straight lines polylines fitted splines Bezi r curves elliptical arcs and helices spirals The creation of curve primitives is very similar to the creation of solids and surfaces The polyline and fitted spline primitives make use of a list of points Here as for polygon surfaces new fields are created if the last field is entered with the mouse and blank points are removed before constructing the geometry The helix component can also create conical spirals by setting the top and bottom radii to different values or flat spirals by setting the height to zero Note that the wire radius see section 4 12 1 is specified on an edge as listed in the details tree rather than on a primitive Specifying the radius for a curve created from the intersection of faces is done in the same way 4 6 7 Importing exporting geometry CADFEKO is built on the Parasolid solid modelling kernel Hence Parasolid models can be imported and exported without any translation December 2005 FEKO User s Manual 4 22 WORKING IN CADFEKO Select File Export Parasolid to export the geometry to a Parasolid file This opens an Export Parasolid model dialog where the choice between Text or Binary format must be m
248. e surface is a metal then one basis function is assigned to each edge If the surface is a dielectric then two basis functions are assigned for the current density one for the equivalent electric current density and one for the equivalent magnetic current density Connection point A connection point is where a segment is joined to a triangle The end of the segment is connected to the vertex of the triangle A basis function is assigned to each connection point EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 3 Cuboid A volume element used to model dielectric and magnetic solids according to the volume current method in the MoM It has 90 degree corners similar to a cube but does not need to have equal side lengths Tetrahedron 3D tetrahedral shaped volume element used in conjunction with the FEM Polygon A planar surface element with straight edge boundaries 2 2 2 Meshing guidelines regarding element sizes For the meshing process the following rules must be adhered to The segment length l should be smaller than where A is the free space wavelength Note also that the segment current flows only in the axial direction Thus segments should not be too short relative to the wire radius Ideally the segment length should be at least four times the radius The area A of each triangular element should be smaller than a For an equilateral triangle with side length s the area is given by A
249. e used in any card following the IN card Label Specifying the label as the last parameter of any structure is optional If no label is specified the value defined at the last LA card will be used Note that if a label or range of labels is specified with parameters after the filename this LA card label will be used to determine if a structure is included or not The radius of segments must be specified by an IP card before the IN card It is recom mended to check the geometry with POSTFEKO December 2005 FEKO User s Manual 9 38 DESCRIPTION OF THE GEOMETRY CARDS Example The structure in figure 9 16 consisting of 5 node points and 3 triangles with label 7 no segments or polygonal plates may be imported from the following data file 5 3 0 0 3 0 0 0 1 0 4 0 2 0 1 0 2 5 3 0 2 5 0 0 3 0 4 0 1 0 0 0 3 0 12 3 0 7 1 3 5 Q T 3 4 5 0 T ZA P1 3 0 1 a oi y P3 2 5 3 2 5 P4 0 3 4 P5 1 0 3 P2 Figure 9 16 Example for IN card EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 39 9 2 18 4 Import NASTRAN file With this option PREFEKO can import a model from a NASTRAN file It supports both 8 character and 16 character wide column based files and comma separated files Only the keywords GRID CTRIA3 CQUAD4 CBAR and CROD for nodes triangles quadrangles divided into two triangles along the shortest diagonal and segments ar
250. e value as such but also frequency radius of curvature of the structure etc For surfaces the unit of Zg is Q For wire structures the value used by FEKO is in units of 2 and results from the surface impedance expression by dividing it by mo where o represents the wire radius Parameters Real part The real part of the surface impedance Zp in 2 for triangles or in 2 for wires Imaginary part The imaginary part of the surface impedance Zp in Q for trian gles or in 2 for wires m For instance to model a solid dielectric object with relative permittivity e and with con ductivity o at a specific angular frequency w 27 f one could use the surface impedance expression 0 Z PE 0Er J ny EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 117 10 2 43 SP card This card is used to calculate the S parameters for the active sources SP Calculate S parameters for active sources System impedance Ohm J Parameters System impedance The reference impedance in Ohm This is used for all sources for which no impedance value is specified when defining the source If this field is empty it defaults to 50 Q Note that for waveguide sources AW card S parameters are always related to the corre sponding waveguide impedance The N ports must be defined before using the SP card They are identified simply by
251. each of these blocks For this case the aim function f is defined as 1 lt 2 a Fij bas 2 Jl using the magnetic near field H when using the magnetic field The negative sign ensures that a minimisation of the aim function maximises the near field As before only the magnitude of the field strength is evaluated in each case Nf gives the number of electric near field blocks to read and NZ the number of lines to read from each of these blocks Similarly N gives the number of magnetic near field blocks and N the number of lines for each block The parameters FF and F are arbitrary proportionality constants that may also be negative The error function is calculated separately for the Electric and Magnetic fields The aim function is the sum of the aim function for the individual error functions i e Z Z 4 4Z Note that the number of blocks of the electric and magnetic fields does not need to be the same For the electric fields the aim function is given by fi 75 DL Eijl S j 1 And for the magnetic fields it is given by H p ve fi se T A Hi l S j 1 The keyword NEARFIELD or NAHFELD is used to specify this aim function December 2005 FEKO User s Manual 11 24 THE OPTIMISER OPTFEKO Near field values This aim function enables one to optimise either the electric or the magnetic near field or both with respect to certain defined field strength values Since the absolute field strength is just scaling l
252. ead from each block Normalisation Field Strength This number indicates which field strength value to use for the normalisation Component The field component that should be used for normalisation See the comments below Weighting factors These factors determine the relative weighting of the components of the field See the discussion below Aim value table The table is used to specify the aim values for the values The optimisation parameters follow the keyword NEARFIELD_VALUES or NAHFELD_WERTE Np gives the number of blocks containing electric or magnetic near field strength values to be read and Ng gives the number of lines to be read from each of these blocks The value Nnorm must be in the range 1 Ng Ng and indicates which field strength value shall be used for the normalisation Each field strength vector either electric Bor magnetic H has three components FE Ez Ez or H H2 H3 respectively For instance in a Cartesian coordinate system the assignment is Fy Ez E2 Ey and 3 E but in a spherical coordinate system one would have El E E2 Ey Ez Ey The value of Neomp which must be 1 2 or 3 determines which component of the Nnormth field strength value shall be used for the normalisation When normalisation has been switched off the component no longer needs to be specified The weighting parameters fi f2 and f3 are discussed below when describing the aim function Let Epi j be the kth with k
253. earest the specified point The percentage is then stored with the edge i e if the object is later scaled or moved the specified vertex will still lie at that percentage from the edge Vertices can also be specified using named points In this case the point is stored with the edge and if the object is later moved or scaled the specified vertex may no longer be on the edge For free edges i e edges not forming the boundary of a surface a wire radius can be specified on the Edge properties dialog Note that wires are displayed as lines in the 3D view i e the radius is not represented 4 12 2 Importing meshes CADFEKO can import a variety of mesh formats accessed with File Import Mesh gt in the main menu For FEK files only the geometry section wire segments triangles unmeshed polygons and tetrahedra is imported the control section is completely ignored Since CADFEKO December 2005 FEKO User s Manual 4 40 WORKING IN CADFEKO specifies dielectric medium boundaries based on face labels it appends an underscore and a number to create unique labels if the FEK file contains different dielectric bound aries with the same label In addition since the imported labels are listed under a new mesh part the labels in the imported model contain an additional level The medium information and segment radii are retained CADFEKO imports the other mesh formats by running PREFEKO and importing the resulting FEK file Curr
254. ecember 2005 DESCRIPTION OF THE CONTROL CARDS 10 17 S parameter impedance The port impedance if this excitation is used in connection with S parameter calculation If this field is empty or 0 the value specified at the SP card is used This value is only used if the S parameters are requested with an SP card The excitation is shown in figure 10 3 A typical application of the A4 card is given in example_30a pre Examples Guide It is of course possible to discretise the vertical pin into segments and feed one of the segments with a voltage source Al card The ad vantage of the A4 card is that there are no vertical currents which results in substantially simpler Green s functions and a significant reduction in computing time Feed triangle Figure 10 3 Excitation of a patch antenna with a vertical pin December 2005 FEKO User s Manual 10 18 DESCRIPTION OF THE CONTROL CARDS 10 2 8 A5 card This card specifies excitation by an electric Hertzian dipole A5 Electric Hertzian dipole New source C Add to sources Magnitude of af Am Po Phase of d degrees Po Dipole position x position y position Z position ss angle E Y angle sis Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Magnitude of I dl Absolute value of the complex amplitude T l in Am Ph
255. ecognised as an ohmic connection This is shown on the left side in figure 2 2 The line AB is divided into four segments and the point C is not on a node To resolve this problem three wires have to be defined AC CB and CD Then there will be an ohmic connection at point C as shown in figure 2 2 on the right D A B C Figure 2 1 Example of a wire structure l Figure 2 2 Incorrect left and correct right subdivision into segments G F E A B H c D Figure 2 3 Example for a surface December 2005 FEKO User s Manual 2 6 GENERAL COMMENTS A similar rule has to be followed when surfaces are subdivided into triangles If the surface in figure 2 3 has to be meshed there are a number of possibilities The surface can be subdivided into the rectangles ABFG and CDEF This can result in the mesh shown in figure 2 4 on the left hand side In this case there is no ohmic connection at the line BF because the triangles vertices are not connected in the sense that the triangles do not have common edges The correct subdivision is shown in figure 2 4 in the middle Here the rectangles ABFG CDHB and BHEF were used Another subdivision is possible using quadrangles ABEG and BCDE figure 2 4 right side BE is now a common edge and the surface will be meshed correctly Care has to be taken to ensure that when two surfaces touch the common edge is part of both surfaces In
256. ection coefficient ground plane C Perfectly electric conducting ground Perfectly magnetic conducting ground Relative permittivity Conductivity S m Relative permeability tan Sy tan Magnetic loss factor Dielectric loss factor No reflection coefficient ground No ground plane or use one of the other ground plane options such as the GF card for an exact model of real ground or the SY card for a perfect ground plane This option is used to switch off the reflection ground if the effect of different grounds are considered in a single input file Reflection coefficient ground plane Use the reflection coefficient ground plane approxima tion with the material parameters specified in the remaining input fields Perfectly electric conducting ground Use an ideal electric ground in the plane z 0 In this case the remaining parameters are ignored Perfectly magnetic conducting ground Use an ideal magnetic ground in the plane z 0 Relative permittivity Conductivity Relative permeability Magnetic loss factor Dielectric loss factor Also in this case the remaining parameters are ignored The relative dielectric constant r of the ground The conductivity o in on of the ground The relative permeability ur of the ground Magnetic loss tangent tan 6 of the ground the complex perme ability is then given by u pokr 1 j tand Electric loss tangent tan 6 an alternati
257. ectric sphere in the field of an incident wave Define the variables tr 1 Radius of the sphere betrad 1 Electrical size of the sphere epsr 15 The relative dielectric constant maxlen 0 7 The maximum edge length Define segmentation parameters IP maxlen The corner points DP A 0 0 0 DP B 0 0 r DP Cc tr 0 0 Select the medium ME 1 0 EM Software amp Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREFEKO 7 7 Generate an eighth of the sphere KU A B C 0 0 90 90 maxlen Use symmetry in all three coordinate planes x yz plane ideal electrically conducting plane xz plane ideal magnetically conducting plane xy plane only geometrically symmetric SY 1 2 3 il End of the geometry EG 1 0 0 0 0 Assigning the dielectric s properties DI epsr 1 0 Incident plane wave excitation freq betrad c0 2 pix r FR 1 0 freq AO 0 1 1 1 0 0 0 180 0 Near fields along the z axis FE 1 1 1 25 0 0 0 0 0 1 98 0 0 0 0 0 04 FE 4 1 1 50 0 0 0 0 0 0 98 0 0 0 0 0 04 FE al 1 1 25 0 0 0 0 0 1 02 0 0 0 0 0 04 End EN The use of variables makes the investigation of structures with varying geometry e g variable distance of the antenna in front of a reflector an easy process because only one variable needs to be changed It also allows FOR loops and IF conditions 7 4 FOR NEXT loops Some cards in FEKO implicitly use loops such as when an FR
258. ed If for example a Hertzian dipole is placed on one side of the symmetry plane the user must also place the correct image on the opposite side of the symmetry plane Multiple SY cards can be used and it is possible to mirror around more than one plane at once A detailed description of the different types of symmetry geometric electric and magnetic symmetry was given in section 2 4 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 91 9 2 38 TG card With this command the already entered geometric elements triangles segments etc can be translated rotated and or scaled It is also possible to duplicate structures Parameters Number of copies Use label selection TG Geometry translation and rotation Number of copies Include by label V Use label selection Copy structures starting from label ending at label Label increment for the new structures Include by type IV Include everything IV Metallic triangles JV Cuboids WV Polygonal plates Y UTD cylinders Iv Metallic segments WV Dielectric triangles Y Tetrahedral elements Rotation around the x axis Rotation around the y axis Rotation around the z axis Translation along the x axis Translation along the y axis Translation along the z axis Scale factor after translation The number of copies to make for example if set to 3 the selected elements will be rotated transla
259. ed by selecting Info Machine code info from the licence manager main menu All licences that match any of these machine codes will be valid on this machine EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 1 4 Working in CADFEKO 4 1 Introduction CADFEKO has been developed to allow the creation and set up of FEKO models in a graphical or CAD environment This involves defining and meshing the geometry of the problem as well as specifying the electromagnetic parameters and solution requirements Currently CADFEKO is used for the geometry construction and meshing phase and EDITFEKO is used to define the solution requirements See the Getting started manual for more details CADFEKO supports parametric model construction If the model is constructed using variables the entire model can be modified by changing these variables This is used for example to tune the size of an antenna for a required frequency and input impedance In addition CADFEKO maintains the construction history This allows for example the modification of individual objects used in a union operation after the operation CADFEKO can also import and mesh complex CAD models in Parasolid ACIS Catia ProEngineer STEP and Unigraphics formats as allowed in the licence It is important that the imported model is of a decent quality If the imported model has overlapping surfaces and gaps between supposedly connected surfaces so will the r
260. ed in CADFEKO and used in the DI card in EDITFEKO to specify the material properties for this dielectric The dielectric names are not hierarchical like the label names This allows using the same name on completely separate parts December 2005 FEKO User s Manual 4 48 WORKING IN CADFEKO 4 16 5 Using symmetry Currently symmetry is specified with the SY card in EDITFEKO This generates new elements i e only one half of the model should be built in CADFEKO Typically the completed model is created and then split along one or more of the principal planes Structures on the symmetry plane require special care When splitting a solid a new face is created along the split plane If the entire model is meshed this face will be included These elements will then be duplicated by the symmetry operation which will result in an invalid mesh The simplest solution is to convert the solid to a shell before splitting it but this option may not always be possible for example if the solid is a dielectric Alternatively these elements can be deleted after meshing or the IN card adapted not to include them A more complex problem involves models which contain structures on the symmetry plane These have to be imported after specifying the symmetry plane First the IN cards with label selected importing should be used to import all geometry not on the symmetry plane then the SY card is specified and finally the structures on the symmetry pl
261. ed such that each mode has a constant power flow through any spherical surface either inwards or outwards In principle one could use the PW card for this but then power normalisation works only if there is not more than one mode active at the same time when using the PW card just the total radiated power of all the modes is determined and then each mode is scaled with the same factor so that the total radiated power is correct but here we enforce a specified power for each individual mode The power for each mode is independent of the mode indices P 0 5 Magnitude of the mode unit is correctly Watt since the amplitude has a unit J W Since the modes are orthog onal if multiple AS cards are active at the same time the powers of the individual modes can just be added Any other power corrections such as due to metallic elements being in the vicinity are not taken into account in FEKO If an AS excitation is used in connection with multiple different media it should be noted that we assume outward propagating modes when Outward is selected under Propagation direction to originate from the Source position i e the source is located in the medium where Source position is located and its contribution will be zero in all other media For inward propagating modes when Inward is selected under Propagation direction we assume them to originate at infinity in the free space medium 0 and such modes only contribute to this medium with in
262. ed with it This weighting factor specifies the relative contribution of each individual aim function to the total aim function If the weighting factor for an aim function is not specified the default value of 1 is used EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 13 Where relevant the following terms are used in this section e Np is the number of blocks in the output file that must be used for the optimisation e Ng is the number of samples per block in the output file e f is as above the aim function as defined per block Gain With this aim function a maximisation of the gain directivity of an antenna in one or more directions can be done The optimisation can be done over a broad band by examining a number of frequencies Aim function Aim 1 Select aim function Gain y Weighting factor fi Polarisation Both Horizontal LHC Vertical RHC CZ Treatment for multiple blocks Averaging over the blocks Take maximum minimax principle Number of blocks IV Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions Polarisation The values in this box can be used to specify which component of the gain should be optimised Treatment for multiple blocks The options in this box are used to specify the method to combine the local ai
263. edia KORP KORM POIP POIM 1 1 5 3033E 01 0 1 1 2 1 1 2 1 3 7500E 01 0 1 1 33 2 3 3 1 3 7500E 01 0 1 65 3 2 information on symmetry yz XZ xy status 0 49 93 unknown 0 2 94 0 0 50 3 unknown December 2005 FEKO User s Manual 14 2 DESCRIPTION OF THE OUTPUT FILE OF FEKO Each edge is assigned a consecutive number which appears in the first column The length of the edge is given in the second column and the medium in which the edge is found appears in the third column On an edge there are exactly two triangles In the columns KORP and KORM the numbers of these two triangles are given and the positive current direction is from the triangle KORP to the triangle KORM In the column POIP the number of the corner point of the triangle KORP which is opposite to the edge is given The same applies to the column POIM The next four columns contain information concerning the symmetry In the column yz the number of the edge appears corresponding to the plane x 0 yz plane of symmetry A positive sign indicates that the currents are symmetric and a negative sign indicates that the currents are anti symmetric If there is a 0 present in this column then a symmetric edge does not exist The same applies to the next columns xz and xy concerning the planes y 0 and z 0 The last column with the heading STATUS has the following meaning If unknown appears in it the edge has an unknown status The applicable coefficient of the current ba
264. ee oS 9 28 9216 PP ead og eka a aoe ee AR RA RRR 9 30 pairt BCA a p ee ee IN 9 31 gal EN GaP coccion a 9 33 Malo Foa cr DRS Se A Oe eee eS 9 52 Oe PAA iia 9 53 a A ee i a i ee BE Deed Hoes 9 54 ie AGG oe oa oe es ed es os el es oP ee E E E 9 58 We AA ce a bk Rak we BO OR El oer re KA Soh 9 59 o ENO e 6 ae eo OR ee RE oe Gs 9 62 A 2 oo Ahhh ee hE EDS PE ES EE ES 9 64 Oe ME Gate on Lora Gage ee oe Pe es Bae Ge ine ee 9 65 December 2005 FEKO User s Manual viii CONTENTS Sa UNI CAR oo ban Sa ae ew AA ee Ee EES 9 68 C229 PEG 26 6 bbb d ee ee RO AREER 9 70 Die E 6 eee oe ke ae dO oe oe ae ewes RI es 9 72 Wee PI Cate e as be kw O A S 9 74 Oak A so cbt bee Ghee ee Ebb EH EG ae 9 76 O22 PY cad oo ono a a eae ew A ES 9 80 C208 QT CAM 3 oa haa ek eee ee eee BRS EGS 9 81 Daa QUA ooa s asiaa a ge a ple GG A a ce Se a 9 82 Owe RM Gat 26 one GOA A Hee S 9 84 DE TED ce as ss ES Bs ey Ae ok oo a SO Eee Ge eG 9 88 EA CAR woe oS ee Pe se ee eS 9 90 9238 Ta card 00 cea ee ee eee ER EG 9 91 9239 TO CAR so baad SW e e EPA R RG Ee ee oe 9 94 Pea WR Gard oo eee GDS oe eR ERS De bo ee SS 9 96 Pal Ulead socios aoa 2 eS BSS Ede ee 9 98 A AURORE oe ok bok ee BS ee ee BD eA Sides 9 100 DOAS OR aap ap we ee es at oe aa Be eee a i E 9 101 AA IN 9 104 D245 ZY CON oe a RS OR Ga a eR Be a 9 105 10 Description of the control cards 10 1 10 1 Overview of control cards and execution sequence 10 1 10 2 Detailed description of the co
265. eld at the top of the control panel If the filename is very long such that it is not fully displayed in this field hovering the mouse over it displays the full filename Note also that it is possible to use the left and right arrows to scroll the filenames while selecting them in the drop down list POSTFEKO automatically creates a new 3D display window each time a new FEK file is loaded with Load model 6 3 1 Zooming rotating panning the model The model can be rotated by clicking and dragging with the left mouse button on the 3D window Clicking and dragging refers to moving the mouse without releasing the mouse button Pressing lt Ctrl gt while clicking and dragging the mouse pans moves the model and pressing lt Shift gt while clicking and dragging the mouse up and down zooms in and out Note that POSTFEKO tries to zoom towards the point where the mouse is clicked Thus clicking at the bottom and dragging the mouse all the way up zooms in but also causes the model to move upward In addition rotating the mouse wheel zooms in at the position of the mouse pointer Clicking and dragging with the mouse wheel pans the model The Render control toolbar on the 3D view provides quick access to these features This toolbar is usually docked at the right of the view but can also be docked at any other side RADGDGDe t ite ETSI ae EAE le canta 4 5 1 ZAS 1 POSTFEKO supports full 3D rotation of the model as w
266. elds are displayed using an italic font to indicate that preview mode is active The snap mode and the snapped coordinate position in global coordinates are shown on the status bar If lt Ctrl gt lt Shift gt is released without clicking on the view the values are reset to what they were before preview mode was activated When editing primitives that have been transformed a dashed outline is drawn at the original position in addition to the solid outline at the final position Some dimensions may be orthogonal to the workplane For example the height of a cylinder when the local coordinates are aligned with the workplane When such values are active while entering points with snapping to the workplane or grid the height is determined by projecting the point to a line normal to the workplane This is only possible when the view direction is not orthogonal to the workplane The view orientation of the model can be changed by left clicking and dragging the mouse as opposed to just clicking even while creating geometry When clicking the Create button all input fields are evaluated If any field contains an invalid expression or a value that is not valid for that parameter such as zero for the radius of a sphere an error is displayed in the message window and the field indicated 4 6 4 Creating solid primitives The Geometry Solid menu contains sub menus to create new cuboids flares a possibly truncated pyramid spheres cylind
267. eleting 4 41 distorted 4 43 free edges 4 43 searching 6 7 ellipse 4 19 ellipsoid 9 25 elliptical arcs 4 21 elliptical hole 9 72 ELSE statement 7 9 EN card 10 70 end of geometry 9 22 end of input file 10 70 environment variables 2 22 EPSENT 9 23 equivalent aperture 10 31 excitation see sources EXIT command 7 11 expand tree items 4 11 explode 4 31 export 4 5 4 46 geometry 4 21 images 6 16 Parasolid 4 16 4 21 raw data 6 15 expressions 4 13 extents 4 16 extrude parts 4 26 faces see surfaces 4 11 4 19 4 31 delete 4 29 metal 4 33 properties 4 38 reverse normals 4 29 far fields 6 8 calculating 10 79 FE card 10 71 feed see sources FEK file format 7 1 FEK files 4 39 FEKO 8 1 FEKO USERHOME environment variable 2 22 13 FEKO_WRITE environment variable 2 22 FEM 9 30 FEMAP 9 35 FF card 10 79 file format 7 1 files 10 66 CFM 4 5 4 46 CFX model 4 5 input 2 1 output 14 1 Parasolid 4 21 PRE 4 5 4 46 summary of 2 19 find elements 6 7 flares 4 18 FM card 9 27 FO card 9 28 Fock area 9 28 FOR NEXT loops 7 7 FP card 9 30 FR card 10 83 13 1 free edges 4 33 4 43 free space 4 31 frequency 10 83 adaptive sampling 13 1 general comments 2 1 geometry CAD translation 4 22 creation 4 16 entering 9 33 extents 4 16 importing 4 22 in tree 4 11 mirror 4 24 modify 4 23 point entry 4 17 rotate 4 24 scale 4 24 show hide parts 4 10
268. ell as a more intuitive Lock z axis option where the z axis remains vertical on the screen 2 Zoom to extents fits the model to the visible window 3 Isometric zoom does a Zoom to extents and resets the view direction 4 Zoom to window zooms to a specific region of the display Click the mouse and keep the button down while dragging the window to zoom to 5 Previous view provides a multilevel view position undo 6 7 Zoom in and Zoom out 8 11 These options increment or decrement the view angles in spherical coordinates 12 15 These options move the model in the plane of the screen EM Software 4 Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 5 6 3 2 The model view control panel Initially the control panel of a new 3D view shows the Main display options page See figure 6 2 This page controls the display of the geometry 2 a TF Named points Tf Label no lel Segments 5 is Metallic triangles 6 E Dielectric triangles Polygons ol 7 Cuboids 8 t Tetrahedra UTD cylinders 1 E Current file hom y Main display options 3 A J Element direction F Normals FP Element no IV Surfaces IV Lines IV Surfaces iv Lines W Surfaces W Lines W Surfaces W Lines W Surfaces WV Lines W Surfaces WV Lines F volume WM Visible o 10 Geometry colour Element type EM properties C Label C Medium Label colours Legend lt No Legend gt X
269. end of the input file In the first format the two excitations are processed one after the other for each frequency The cards are executed in the order FR Ax Ax FR Ax Ax EN where the second FR indicates execution of the frequency loop for the second specified frequency In the second format the first excitation is treated for both frequencies before treating the second excitation for both frequencies Here the cards are executed as FR Ax FR Ax FR Ax FR Ax EN For the computational requirements one finds that in the first case the matrix elements have to be calculated twice it have to be completely recalculated each time the frequency is changed and in the second case four times The computation time is not only influenced by the control cards but also by what has to be solved for In the following example the structure has to be solved at a number of frequencies and for the ideal conducting and non ideal conduction with losses cases FR FR card for multiple frequencies FE calculation of the near fields SK include skin effect FE calculation of the near fields EN end of the input file The three control cards FE SK and FE are written to the buffer and are worked through in the loop for the different frequencies At the first frequency the FE card initiates the field calculation Because a SK card has not yet been read ideal conductivity is assumed Then the SK card is read and losses are taken into account w
270. ently FEMAP neutral files boundary surfaces bordered with line curves are imported as mesh polygons NASTRAN PATRAN STL meshed AutoCAD DXF files only the LINE and POLYLINE structures which defines segments and trian gles Ansys CBD and Concept files are supported For information on these formats see section 9 2 18 For all formats except FEK files CADFEKO opens an additional Import mesh dialog Here the user can set a scale factor and control which elements to import For example boundary elements in FEMAP neutral files may be either part of the geometry i e it should not be imported or intended as mesh polygons i e it must be imported Quadrangles are divided into triangles during the import process Only Ansys CBD files support segment radius information for all other formats a default radius must be specified on the Import mesh dialog The default radius is also used for Ansys segments where a radius is not defined in the file Different radii can be set on the segments after importing Finally for AutoCAD DXF files the LINE elements are divided in segments according to the value of the Segment length field If the LINE elements must not be subdivided this value must be larger than the longest line Since these formats do not support specifying dielectric media all segments triangles and polygons are in free space and all tetrahedra have the medium Unknown It is of course also possible to import meshes manuall
271. entre point of the circle when creating a conical section A point on the radius of the base If this parameter is defined the cone is cut off at the top if not the cone has a sharp tip This point must be in the plane given by S1 S2 and 83 The angle y from the plane S2 S1 S3 at which the bottom of the cone should start The angle y from the plane S2 51 83 at which the bottom of the cone should end The angle y from the plane S2 S1 53 at which the top of the cone should start The angle y from the plane S2 S1 53 at which the top of the cone should end EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 55 Maximum edge length bottom The maximum edge length of the triangles along the base arc in the plane containing S1 of the cone This value is in m and is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Maximum edge length top This value only applies if S4 is specified and gives the maxi mum edge length of the triangles along the top arc in the plane containing S2 of the cone This value is in m and is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Normal vector directed The triangles can be created such that the normal vector points Outward away from the axis or Inward to the inside of the cone Scale second half axis If this paramet
272. ents and charges Selecting specific entries under label can significantly reduce the number of entries under segment making it simpler to find the correct segment 2 Add a source data graph plots source related information such as input impedance and losses An arbitrary load can be subtracted with the Subtract loading field If Impedance is selected the specified value is subtracted from the impedance as if it is in series with the input impedance If Admittance is selected the value is subtracted from the admittance as if the load is parallel to the input impedance The Reference impedance is used for S11 and VSWR calculations December 2005 FEKO User s Manual 6 12 WORKING IN POSTFEKO Add S parameter graph plots S parameters calculated using the SP card Add a power data graph plots the active power loss power and efficiency of the selected source Add a non radiating network graph plots the impedances voltages and currents at the ports of transmission lines Add a Far Field graph plots the radiated fields Add a Near Field graph plots graphs of near field values 6 5 4 Series manipulation toolbar This toolbar is used to control the series information for each graph aleji 2 3 E Bb 3 4 Delete the current series This button will remove the current series from the graph The currently selected tab determines which series is removed New Series adds another default series to the graph Copy S
273. eometry and model validation 6 4 6 3 1 Zooming rotating panning the model 6 4 6 3 2 The model view control panel o 6 5 64 Displaying 3D results oa us a sees bee Ea aS 6 7 6 4 1 Beal view toolbar a a Ye ee 6 8 6 4 2 3D result SElECHOW soa e eke OR ka ES 6 9 Go Display mg 2D reslis e oss sads a WO WOR ee eae A ee 6 10 6 5 1 2D result acle cho eog e eara Topaia a 6 10 December 2005 FEKO User s Manual vi CONTENTS 6 5 2 6 5 3 6 5 4 6 5 5 6 5 6 6 5 7 6 5 8 6 5 9 Continuous adaptive frequency sampling New 2D graph toolbar coo o cocoocro aros Series manipulation toolbar 000 Graph settings toolbar ssa ccoo asinan ces Zooming rotating panning the model Value series description 00 000000 PFG graphs and importing GraphFEKO WFG graphs Loadi a and saving raw data o coace roe es 6 6 Exporting images 3D 2D o o GY Polarisation e cec 8 aid avr a a ee eS aaa Re be 6 8 Viewing the output file o 6 9 Advanced troubleshooting features o o 6 9 1 6 9 2 Database browser o o scada carr ee ES Help went A 7 The preprocessor PREFEKO Rl Der iwc eae eee eee bee be Ewe N Te Runnings PREFERO oc iaa ee SO eae da ae fa symbole variables oc a sa 2444 545 08504333 44445 4 74 POR SNERT loops a cee acire eaen ve eee Re eee 7 5
274. er These elements can be removed by deleting vertices see section 4 13 5 Oversized elements are found based on the maximum edge length 4 13 8 View free mesh edges and segment nodes Another very important issue is connectivity In addition to the tests on the geometry CADFEKO allows finding unconnected edges and segment vertices This is done by selecting Find Free mesh triangle edges or Find Free segment nodes from the main menu These operations test only the selected elements and will not report free edges vertices if the element is connected to another unselected element For segments all vertices which are not attached to another segment or a triangle corner are selected These vertices can be completely acceptable for example at the end points of wire antennas However if two such points lie very close together they should be merged December 2005 FEKO User s Manual 4 44 WORKING IN CADFEKO Triangle edges are considered to be free if they are not attached to other triangles An edge is only connected to a triangle if both end points coincide with corner points of the triangle Here the two vertices at the ends of the edge are selected These vertices may then be merged moved or whatever is required to make the model consistent Again free edges may be perfectly normal such as on the edge of a finite boundary 4 13 9 Editing mesh vertices A mesh vertex can be modified by selecting it mesh vertices mu
275. er is empty or is set to 1 a cone with a circular cross section is created If set to 2 a cone with an elliptical cross section is created Here 2 gives the ratio of the two half axes where a is the distance S1 53 It is recommended to generate elliptical cones with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases The fineness of the mesh on the shell s surface is determined by the maximum edge length specified by the last IP card prior to the KK card Along the arcs accurate modelling of the geometry may require finer segmentation and the values Maximum edge length bottom and Maximum edge length top specify the maximum edge length along the corresponding arcs Maximum edge length top is only used when a truncated cone is created If either of these values is not specified the length specified with the IP card will be used on the corresponding arc December 2005 FEKO User s Manual 9 56 DESCRIPTION OF THE GEOMETRY CARDS Examples of KK card usage All of the following meshes are created using the KK card These examples show a sharp cone an oblique elliptical cone a conical section with different angles at the top and bottom and a conical section where the start angle is not in the plane S2 S1 S3 DD f ADO ENW Figure 9 18 Example of a cone with an elliptical cross section from demo_KK2 pre EM Software a
276. ere is no reduction in memory usage There is however a reduction in computation time when the matrix elements are determined 2 4 2 Electric symmetry An electric symmetry plane is a plane which can be replaced by an ideal electrically conducting wall without changing the field distribution In figure 2 9 an electric symmetry plane is displayed The electric E field s tangential com ponent disappears and the magnetic Hi field s normal component disappears The electric current density J is anti symmetric and the magnetic current density M is symmetric As with geometric symmetry less computational time is required to calculate the matrix elements The number of unknown coefficients of the current basis functions are reduced leading to linear equation system of a lower order This leads to a further reduction in the computation time and requires less memory due to the reduction in matrix elements gt gt J M A Plane of electric symmetry gt Figure 2 9 Electric symmetry plane 2 4 3 Magnetic symmetry A magnetic symmetry plane is a plane which can be replaced by an ideal magnetically conducting wall without changing the field distribution In figure 2 10 a magnetic symmetry plane is displayed The electric E field s normal component and the magnetic field s tangential disap pears The electric current density J is symmetric and the magnetic current density M is asymmetric December 2005 FEKO User s
277. erent radius values for the start and end points of the wire a tapered wire can be created S Figure 9 1 Sketch illustrating the use of the BL card S EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 5 Examples of BL card usage The BL card can be used to create segmented wires as shown in figures 9 2 and 9 3 In the first example the radius is specified with an IP card and in the second an exaggerated taper is specified at the BL card Figure 9 2 Example of a BL card from demo_BL1 pre SS SSS Figure 9 3 Example of a BL card with a tapered radius from demo_BL2 pre December 2005 FEKO User s Manual 9 6 DESCRIPTION OF THE GEOMETRY CARDS 9 2 3 BP card A mesh of surface triangles in the shape of a flat parallelogram can be created with this card In general this card is replaced by the PM card This card should only be used when the user wants to force the very regular meshing that this card produces BP Specify a parallelogram Sa b sj E sj 4 F sf y S ssf I Specify non uniform meshing Mesh size along sides a and c a Mesh size along sides b and d A Parameters S1 S2 S3 S4 The points S1 to S4 are the four corner points of the parallelo gram These points should have been defined previously with DP cards Specify non uniform Normally a parallelogram is segmented according to the edge length specified with the IP card I
278. eries copies the current series This would be identical to creating a new series and then modifying all the series settings to be the same as the current series Copy to value series creates a new series which is a value series of the current series See section 6 5 7 Convert to value series converts the current series to a value series When a series is copied or converted to a value series the original data is used and any offset or scaling factor must be applied again to the new series Perform calculations on series opens a dialog where calculations can be performed on a series or between multiple series When using this the syntax is the same as the syntax for PREFEKO when dealing with variables For example to add two series together the syntax would be series_1 series_2 The result of this computation is saved as a value series Note the character preceding the name of the series as given in the tab on the control panel Tf the Limit operations to the common region is checked the calculation is only done in the region where all series have values Interpolation between values is done Tf unchecked a value of 0 is assumed where a series is used outside its range Rename series opens a dialog that can be used to change the name of a series EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 13 6 5 5 Graph settings toolbar This toolbar located on the far left when a 2D graph has focus
279. ers or cones The entry process is very much the same for all primitives so this discussion deals primarily with cuboids The Create cuboid dialog shown in figure 4 5 allows creating cuboids It requires the position of one corner and the dimensions along the three coordinate directions Negative values are drawn in the negative axis direction EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 19 A create cuboid ES Geometry Local TF Use global coordinates First comer ufo of y feo pl wo joa of m Dimensions Width 1 Joo Depth V Joo Height N fo 0 Label Cuboid1 Figure 4 5 The geometry panel of the Create cuboid dialog A new object is created each time the Create button is clicked When all the required cuboids have been created click Close or press lt Esc gt to close the dialog The dimensions must be non zero If any dimension is zero CADFEKO will display an error in the message window and indicate the offending field The object will not be created Where allowed such as the width of a cuboid negative values are taken in the opposite direction The Label field allows entering the name of the new object This is visible in the tree and can be changed at any time If the Radius field for a sphere or cylinder is specified with a point the surface of the sphere or the extended cylinder will pass through that point For a cone the radius is deter
280. ervation Point r cosy r rsing Unit vectors of the coordinate system COS P sin p 0 r sing g cos p z 0 0 0 ik EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 75 e Spherical coordinates r p Pr Figure 10 19 Field calculation in the Spherical coordinate system Observation Point r sin cos y r rsinv sing r cos Unit vectors of the coordinate system sin Y cos y cos cos Y sin p r sinvsing 0 cosvsiny p cos Y cos Y sind 0 December 2005 FEKO User s Manual 10 76 DESCRIPTION OF THE CONTROL CARDS e Cylindrical coordinates around the x axis r p x Zz A y x y Figure 10 20 Field calculation in the Cylindrical coordinate system around the x axis Observation Point x T rcosp r sing Unit vectors of the coordinate system 0 0 1 f cos p p sing C 0 sin p COS p 0 EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 77 e Cylindrical coordinates around the y axis r 9 y Zz A Figure 10 21 Field calculation in the Cylindrical coordinate system around the y axis Observation Point r cosy r y r sin Y Unit vectors of the coordinate system cos p sin p 0 f 0 p 0 y 1 sin cosy 0 December 2005 FEKO User s Manual 10 78 DESCRIPTION OF THE CONTROL CARDS e Conical coordinates around the z axis y z This option is
281. es from the main menu and selecting the Appearance tab Note that the splitter between the editor and the dialog panel may be dragged to resize the panel 5 1 1 File control toolbar kd b fo Co bel S 1 2 3 4 5 6 Used for file and print control The functions of the buttons are Create a new pre file and switch to PREFEKO mode Create a new opt file and switch to OPTFEKO mode Create a new tim file Open a file and switch to the appropriate mode Save the current file QO oF Ww N rR Print current file EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 3 5 1 2 The edit and window toolbars Ss 8eo 5020 1 2 3 4 5 6 7 8 9 10 The edit toolbar provides standard edit commands while the window toolbar allows po sitioning the edit windows in the editor area The functions of the buttons are 1 Undo Multiple undo commands are supported 2 Redo When new text is added by typing or adding a card the redo chain is cleared and the new text forms the last entry in the undo chain Cut Copy Paste Search for text Cascade all edit windows Tile windows vertically Oo GOAN QARA WwW Tile windows horizontally 10 Arrange windows as best as possible 5 2 Menu items in EDITFEKO 5 2 1 File menu The File menu allows opening and closing files and is similar to standard Windows appli cati
282. es toolbar button The first cutplane is created automatically when the dialog is opened The Add button creates additional cutplanes The Remove button deletes the current cutplane while unchecking the Active item deactivates the cutplane without losing all its settings The Flip button hides items on the other side of the cutplane The cutplane is specified similar to the workplane see section 4 3 1 using an origin and two vectors These fields all use the standard point entry see section 4 6 3 Thus the cutplane can be interactively modified The plane preview is shown in all 3D windows and accepts point entry from any window but it applies only to the current window The cutplane is updated with each change in the dialog Closing the dialog with Cancel reverts to the state when the Apply or OK button was last clicked Where a cutplane passes through solids the cut surface is displayed in a slightly different colour These surfaces cannot be selected thus clicking on them will select geometry that lies behind the cutplane These surfaces are only shown when the current selection see section 4 11 mode is geometry parts When selecting anything other than geometry parts CADFEKO cuts solids similar to shells showing only the actual faces allowing access to the internal faces and edges The cutplane icon on the right of the status bar is active if the view under the mouse cursor has active cutplanes Like the snap options this applies
283. esult is the common part of all the selected parts For Subtract all the selected parts are subtracted from a final part which must be selected when prompted for When only one part is selected the only Boolean operation allowed is Subtract No Boolean operation is available when there are no selected parts Surfaces and wire bodies are also parts Boolean operations cannot be applied to parents or the regions faces edges of parts 4 7 4 Split parts Selecting Geometry Split from the main menu will open a dialog where the split plane can be specified similar to the way the workplane is defined The split plane defaults to the workplane of the active view This operation creates two new parts named Split_back and Split_front where the Front side of the split is in the direction of the positive N axis of the split plane for each selected part The two halves of each split are derived from independent copies of the original part Thus if the entry under Components is modified for one half the other half remains unchanged and has to be modified separately If synchronised changing is required the original part must be created using variables The split plane may be modified by selecting the new part and selecting Properties from the pop up menu 4 7 5 Spinning and sweeping parts Selecting Geometry Sweep or Geometry gt Spin from the main menu also available on the Modify geometry toolbar sweeps also referred to as extr
284. esulting CADFEKO model Refining such models is a considerable task CADFEKO is available on MS Windows 2000 2003 XP and on Linux systems using glibc 2 3 or later 4 1 1 Starting CADFEKO If CADFEKO is properly installed as part of the FEKO installation it can be started from the FEKO folder in the MS Windows Start menu or by opening a console and typing cadfeko It is possible to specify a filename on the command line for example cadfeko model Only CFX files i e CADFEKO models or their associated CFS workspace files are allowed here The filename may be specified with or without extension If the file does not exist CADFEKO creates a new model provided the current specified directory does not contain a CFS PRE or CFM file with this name If such files exists CADFEKO will start with a blank model On MS Windows any CFX file can be opened by double clicking on it 4 1 2 Display settings and graphics cards CADFEKO can be used with 256 colours but a colour setting of at least 16 bits is recommended In addition practical use of CADFEKO will require a screen resolution of 1024x768 or larger December 2005 FEKO User s Manual 4 2 WORKING IN CADFEKO CADFEKO uses OpenGL for rendering and this depends on the graphics card being used and the drivers installed for it With a properly installed graphics card that supports 3D hardware rendering a considerable speedup in visualisation should be seen See the graphics card s
285. example the files dipole pre and dipole opt have been created OPTFEKO is run with the command optfeko dipole On the command line the following parameters can be added f The pre and out are deleted after each analysis This saves disk space R Same as r but the files of the optimum solution are kept Z The value of the aim function is calculated for one existing file no optimisation is done This is mostly used for debugging resume Resumes an optimisation process that has been stopped provided that the files sta and bat are still available for example the previous optimisation has been stopped by pressing lt Ctrl gt lt C gt or due to a power failure or a FEKO error etc For Windows this option must follow right after the filename i e one must call optfeko file resume r and not optfeko file r resume runfeko options After this option one can specify additional options which will be used in the launcher RUNFEKO for the FEKO kernel For instance in order to use the parallel FEKO solver during the optimisation one can use the command optfeko file runfeko options np 2 or also optfeko file runfeko options np 2 machines file m where m indicates the machines file For a remote execution of the FEKO runs during the optimisation on another host the suitable command would be optfeko file remote host hostname See section 8 2 for a list of all such RUNFEKO options Information on the op
286. eye 1 j tan jZ Normally either or tand is entered as zero but it is possible to specify both for example to approximate a specific frequency response FEKO will give a warning which may be ignored The triangles with the label Affect all structures with label exist in a certain environment Ee He Which is usually specified with the EG card It is also possible to place the triangles December 2005 FEKO User s Manual 10 114 DESCRIPTION OF THE CONTROL CARDS within a dielectric body in this case the environment is specified by the parameters of the DI card An additional condition is that the triangles should be geometrically thin i e d must be small relative to the lateral dimensions The mesh size is determined by the wavelength in the environment i e in the medium e pe Thus the layers must be thin relative to the wavelength in the environment When used with the MoM the use of Triangles as thin isotropic dielectric sheet requires that u fe and e e For a single layer the card consists of only one line The surface impedance as used by FEKO is then La L 2jw e e sin 82 where 86 w ep is the propagation constant An example is given in example_32 Examples Guide For multiple layers the card requires one line per layer with the parameters of the first layer on the same line as the card name The approximate surface impedances of the different layers are added to determine the
287. f the surrounding medium the option Wire coating Volume equivalence principle is recommended Note that for wire coatings no surface triangles with the same label are allowed Likewise for surface coatings no segments with same label are allowed If Dielectric magnetic surface coating the electrically thick coating is used it must remain consistent for the whole FEKO run It cannot be on for one solution and off for the next It is however allowed to change the thickness and the medium parameters of the coating December 2005 FEKO User s Manual 10 66 DESCRIPTION OF THE CONTROL CARDS 10 2 24 DA card With this card some data like near fields or S parameters can be exported to additional ASCII files The card allows to switch this export on and off and affects only cards for the computation of for example near fields or S parameters that follow the DA card By default no export files are created DA Write additional data files F3 Write electric fields to efe file J Write magnetic fields to hfe file J Write far fields to ffe file J Write currents to os file F Write residue of iterative solution to cgm file F Write S parameters to Touchstone snp file F Write spherical wave expansion to TICRA sph file Parameters Write electric fields The electric field strength is stored in a efe file Write magnetic fields The magnetic field strength is stored in a hfe file
288. f different refinement options are desired say for wires and triangles one can use one RM card create or import say just triangles and then use another RM card and after this create or import just wires etc When the actual remeshing is done then for each created or imported mesh element e g a triangular surface patch element PREFEKO internally loops over all the RM cards which are active at this time and determines the local mesh length for each RM card and the smallest of these is then used for the actual mesh refinement of the specific mesh element under consideration If one RM card specifies a global mesh refinement then the local mesh size is readily given by the global finer mesh size If one does local mesh refinement with respect to a point then first the distance of the mesh element to this point is determined Similarly for a line or a cable harness the shortest distance from the mesh element to this line or cable is determined If we assume that this distance is d then the local mesh size s is given by the equation 2 81 dz d s s d di This means that for a distance d d we get the mesh size s s and for the distance d da the mesh size is s s2 For any other distances smaller than d in between d and da or also larger than da a linear interpolation is used by means of the formula above Thus the linear increase of the mesh size also continues for larger distances but one shou
289. f propagation RHC The right hand circularly polarised component The polarisation vector ro tates clockwise when viewed at a fixed position in the direction of propagation EM Software 4 Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 17 e Z 45 deg When viewed in the direction of propagation the Zy unit vector points downwards and to the left The unit vector for Z polarisation is then Ez Ep V2 which lies along an axis rotated 45 degrees from horizontal in a counter clockwise direction coinciding with the direction of the diagonal line of the Z e S 45 deg Here Es Eg Ep V2 which is rotated by 45 degrees from horizontal and lies in the direction approximated by the diagonal of the S S polarisation Z polarisation Horizontal pol Vertical pol eg eg Figure 6 4 Polarisation orientation as viewed at a fixed position in the direction of propagation 6 8 Viewing the output file The text OUT file contains the FEKO results in human readable format It is also the only place where one can see the text of the warning and error messages The OUT file is displayed by clicking the View the OUT file button on the main toolbar It is possible to search for a specific phrase by entering it in the Phrase fields and clicking Search Selecting a word in the Keyword drop down list enters the phrase associated with that keyword If only one model is loaded or a 3D v
290. ferent properties are selected some input fields may be blank If these are left blank CADFEKO will not change those properties when other changes to the dialog are applied December 2005 FEKO User s Manual 4 46 WORKING IN CADFEKO It should be noted that these properties are associated only with the mesh If the model is remeshed they are lost unless the mesh was renamed first in which case there will be a large number of duplicate or clashing elements Hence it is not recommended to set mesh properties on meshes where the geometry is available These tools should be reserved for use on imported meshes 4 14 Preferences Select Options Preferences to set the default coordinate system for geometry primitives see section 4 6 and the number of undo steps to keep in memory Since a large amount of memory is used to make provision for undo operations on the mesh reducing the number of undo entries can significantly reduce memory usage during mesh manipulation 4 15 Running components The CADFEKO model is saved as a CFX file Solving this model with FEKO requires two additional input files namely the CFM file which contains the mesh information and the PRE file which controls the solution process CADFEKO automatically exports the current mesh to the CFM file each time a component is started from the Run menu The CFM file can also be exported directly see section 4 2 2 using File Export gt CFM file This allows for ex
291. figure 2 3 the edge BF is such an edge That is why the right part of the surface is not allowed to be defined as the rectangle CDEF because BF is not an edge of this rectangle The recent introduction of the PM card now also allows defining a single polygon ABCD H E F G resulting in a correct mesh Also when using CADFEKO and meshing a polygonal structure with an arbitrary number of corner points the created mesh will be correct A connection point between a segment and one or more triangles is only recognised when the beginning or the end of the segment lies on the vertex or vertices of the triangles In figure 2 5 the left side is an incorrect and the right side a correct connection here the segment is connected to six triangles Figure 2 4 Incorrect left and correct middle and right subdivision into triangles Figure 2 5 Incorrect left and correct right connection between a segment and triangles EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 7 Figure 2 6 Incorrect left and correct right connection between curved edges When curved structures circles spheres are modelled a finer mesh may be used along the curved edges to get a more accurate representation of the geometry When connecting curved edges in PREFEKO the same maximum edge length has to be used for both edges See the example in figure 2 6 Again als
292. files will be put there for the duration of the FEKO run After the completion of the remote run all files will be copied back to the client and this temporary subdirectory on the remote machine will be removed again A final note shall be given which applies to remote launching of parallel FEKO jobs e If a machines file is specified while launching the job locally this will also be used on the remote host i e it will be copied over So one can from the local client configure to run for instance a parallel job on the hosts node1 and node2 but launch remotely on some other computer control_node This makes sense when one wants for instance to start a parallel FEKO job from a Windows PC on a Linux cluster e When during the remote launching no local machines file is specified from the GUI it will always be there but from the command line this can be omitted then the parallel hosts are found using some default machanism environment variable FEKO_MACHFILE default location for the file machines feko etc see section 8 2 2 EM Software 4 Systems S A Pty Ltd December 2005 THE FEKO SOLUTION KERNEL 8 7 It is important to realise that these default options are used as set on the remote host where the parallel job is launched this is e g the control node of a parallel cluster Thus for instance we will read the machines feko file on the remote host and not on the local host where jobs are launched December 2005 FEKO User
293. for multiple aim functions to be used in one optimisation Unfortunately no optimisation algorithm can guarantee an optimum solution by specify ing only the parameters and the aim FEKO supports a variety of optimisation functions Each one is discussed along with its own parameters in this section 11 1 Preparing input for OPTFEKO OPTFEKO requires two files for successful execution The first is a pre file and the second is an opt file The contents of both of these files is prepared using the preprocessor EDITFEKO see Chapter 5 11 1 1 More on the pre file The first required file is the normal pre input file for PREFEKO where the symbolic variables are used to define at least the part of the model that needs to be optimised During optimisation these variables are varied by OPTFEKO This is done by repeatedly generating new pre files in which the optimisation parameters are assigned to the symbolic variables The user usually needs to have default values for these variables that can be used when running PREFEKO to view the geometry prior to running OPTFEKO This must be done by using the DEFINED function An example is given in section 11 4 11 1 2 More on the opt input file The optimisation method its parameters and the aim of the optimisation are stored in a second file with the same filename as the pre file and an opt extension Since the EDITFEKO GUI is used to prepare this file only a general understan
294. found in this line is ignored by PREFEKO It is possible to add a comment to the end of an existing line or card For example Definition of parameters lambda 1 0 Wavelength radius lambda 2 Cylinder radius height 2 lambda Cylinder height December 2005 FEKO User s Manual 9 4 DESCRIPTION OF THE GEOMETRY CARDS 9 2 2 BL card This card is used to connect two points to form a line which is then subdivided into wire segments Parameters Start point of wire End point of wire Set wire radius Radius at start Radius at end BL Specify a wire element Start point of wire End point of wire J Set tapered wire radius Radius at start point of wire Radius at end point of wire The start point of the wire previously defined with the DP card The end point of the wire previously defined with the DP card If checked the radius set at the previous IP card is overridden for the current wire This setting does not affect segments created after this card Both radius values are in m and are affected by the SF card scaling factor If only the start radius is specified the wire will have a constant radius The radius of the wire at the start point The radius of the wire at the end point The points have to be defined by a DP card prior to using this card The wire radius is set by an IP card preceding the BL card but can be set locally Note that by using diff
295. g surface AW Excitation by an impressed mode on a waveguide port TTo use this the CableMod PCBMod module must be activated if required please contact your distributor EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 7 The different ways to realise a voltage source are summarised in figures 10 1 and 10 2 The impressed electric field strength is indicated by E More than one excitation is also allowed Thus one may for example generate an ellip tically polarised plane wave by super imposing two out of phase linearly polarised plane waves with different amplitudes It is also possible to feed an antenna with two different voltage sources For this purpose the parameters New source and Add to sources are available in each Ax card This parameter indicates whether the current excitation is additional Add to sources or not New source When New source is selected only the current excitation will be used and the excitations prior to the current one will be erased For the excitations Al A2 A3 A4 and A7 it is possible to select the feed element through the label Alternatively the position of the feed is specified in Cartesian coordinates This should simplify the modelling in most cases especially with the A7 card FEKO then searches for a segment or an element at this position This comparison of the position uses the tolerance parameter Maximum identical distance EG card
296. ger than this factor all components of the target vector are uniformly multiplied with a value lt 1 with reference to the actual value of this vector thus reducing the length of the aim vector The default value for STPMX is 100 Termination TOL_X TOL_X is also a termination factor in addition to the convergence is above the target vector for the line search It is related to the maximum component of the quotient of the current direction and maximum component of the previous aim vector This expression alamin vector This expression alamin is the lower bound of the step width factor lambda alam during the examination of the value of the aim function in a direction The line search is terminated when alam lt alamin The standard value for TOL_X is 1 0E 7 Termination ALF_F ALF_F presents another method to terminate the line search This happens when there is a sufficient decrease of the current value of aim function in comparison with the previous one Suf ficient here refers to the fact that the current value must not only be absolutely smaller but must be smaller than the previous value less the factor ALF Starting_Gradient where Starting_Gradient refers to the gradient at the previous point The standard value for ALF 1 0E 4 DFP 1 BFGS 2 formula This parameter is used to choose the desired process to de termine the direction for the new line search from the gradient calculation the parameter 1 i
297. gments or between a segment and a triangle ground plane or polygonal plate Only one segment with this label should be declared If there is more than one segment with this label then only one node will be fed Alternatively one may select the item Set source position then the feed node is determined by specifying its Cartesian coordinates in the Coordinates of node group These values are in m and may be scaled by the SF card Magnitude of source Magnitude of the voltage Uo in V Phase of source Phase of the voltage Uo in degrees S parameter impedance The port impedance if this excitation is used in connection with S parameter calculation If this field is empty or 0 the value specified at the SP card is used This value is only used if the S parameters are requested with an SP card There may not be more than two segments connected to the node The direction of the vector points in the same direction as the basis function that has been assigned to this node When only one segment is connected to the node the direction is away from the segment This is the direction of the current flow through the node The internal EMF electromagnetic force of the impressed voltage is in the opposite direction December 2005 FEKO User s Manual 10 14 DESCRIPTION OF THE CONTROL CARDS 10 2 6 A3 card This card realises excitation by a magnetic ring current TEM frill on a segment This will give an accurate model of a coaxi
298. guration Host name Add machine Remove machine Cancel Figure 8 1 Dialog for the parallel host configuration EM Software amp Systems S A Pty Ltd December 2005 THE FEKO SOLUTION KERNEL 8 3 A special note for parallel Windows PC clusters FEKO must be installed in the same location on each host and it is recommended that the parallel job is started from a PC that forms part of the cluster and that this host is listed first When the user clicks OK on this window the hosts are saved to a file machines feko in the directory specified by the environment variable FEKO_USER_HOME This file is then used in the actual parallel process launching VAasoluton options T PREFEKO FEKO utilities TF Only check the geometry Process priority Normal Environment variables Environment variables are specified one per line with the format VARIABLE VALUE Remote execution Remote host hostname or IP address server Parallel execution I Force MPICH F Full CPU report with run times for individual processes FF Output MFLOPS rate of each process without network communication time FF Network latency and bandwidth Advanced OK Restore defaults Cancel Za Figure 8 2 Dialog for setting FEKO solution options On the main Solution options FEKO panel as shown in figure 8 2 some further settings can be made If the Output MFLOPS rate and Network latency and
299. h a global mesh refinement option a threshold can be set RM Remeshing and mesh refinement Remove all existing remeshing rules Seta new remeshing rule C Add a remeshing rule to existing ones Global mesh refinement Local mesh refinement for a point C Local mesh refinement for a line C Local mesh refinement for a cable harness IV Mesh polygonal plates Reference point Distance D1 tt Mesh size at D1 lt Distance D2 sis Mesh size at D2 Po Parameters Remove all existing Clear all previously defined remeshing rules i e the behaviour is as if no RM card was read This option is useful if after having imported a structure using mesh refinement one wants to import another structure or create objects directly in PREFEKO and for these new structures no mesh refinement shall be used If this option is checked all the other parameters are ignored EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 85 Start a new remeshing rule Set a new remeshing option previously read RM cards will be discarded Add a remeshing rule Add a remeshing rule to the already defined ones i e existing RM card rules will be kept the new rule will be added to these Global mesh refinement Global mesh refinement using the specified finer mesh size Local mesh refinement for a point Here an adaptive mesh refinement is performed to ob tain a finer mesh cl
300. h controls whether two points are considered to lie at the same point in space If it is checked all geometrical dimensions and coordinates are scaled This includes in addition to the parameters listed above the following The coordinates of the source point specified in the excitation cards Al A2 A3 A4 A5 A6 A7 if the selection is not made by label Coordinates of the origin of the radiation pattern specified with the AR card Coordinates of the start and end points of the impressed currents for the AI and AV source cards as well as the wire radius specified with these cards Radii of the coaxial feed in the A3 card Radius of the approximated connecting segment in the A4 and L4 cards Positions where the near field is calculated with the FE card Offset in the near field calculation OF card section 10 2 37 Note that if for example all data is specified in mm with the scaling set to 0 001 all input values are interpreted as mm This also applies to the segmentation parameters IP card and possible translations TG card December 2005 FEKO User s Manual 9 90 DESCRIPTION OF THE GEOMETRY CARDS 9 2 37 SY card Here symmetry can be used to generate the geometry and to reduce computation time SY Specify symmetry of the geometry Select symmetry for the plane x 0 None Electrical Geometrical C Magnetic Select symmetry for the plane y 0 None Electrical Geometrical C Magnetic
301. has been discussed above 2 On the Advanced display options page segment radii can be enlarged to display them clearly elements can be shrunk to better see the connecting points edges and the length of the normal vector can be adjusted In addition it is possible to make the geometry partially transparent This page further facilitates selecting which ground plane Green s function card to display and how to display it The Green s function layers can be shrinked to see the borders clearly and to view elements that lie on such boundaries Finally it is also possible to control the display of anisotropic dielectric layers set with the SK card if applicable 3 The Axis settings page controls the visibility of the small orientation axis as well as the main axis A grid can be positioned along any of the three Cartesian planes and moved orthogonal to itself If the Autoscale option is off the length of the axis can be set manually 4 The View transformation page facilitates specifying the view direction model size and light direction The light position is defined in terms of offset angles relative to the view direction Moving the light position can reduce bright specular reflections from small parts of the model It is also possible to store and playback a series of view directions camera positions 5 The Requested fields page facilitates viewing the positions specified with the FE and FF cards where near and far fields wi
302. he axis of the ellipsoid in this direction Begin angle Va Start angle of the ellipsoid in degrees Begin angle pa Start angle of the ellipsoid in degrees End angle Ve End angle of the ellipsoid in degrees End angle pe End angle of the ellipsoid in degrees Maximum triangle edge length Maximum length of the triangles along the curved edge in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used December 2005 FEKO User s Manual 9 26 DESCRIPTION OF THE GEOMETRY CARDS Note that the angles Y and y are defined in an elliptical rather than in a spherical coordinate system For a Cartesian coordinate system with origin Sl x axis in direction of S3 y axis in the direction of 4 and z axis in the direction of 2 a point on the surface of the ellipsoid is given as a sin cos p r y bsin sing z c cos Y where the lengths a b and c are the lengths of the ellipsoid s three half axes For example the length a is the distance between the points 3 and S1 The normal vector of the generated triangles always points outwards The algorithm used for the segmentation can fail if the ratio of the half axis is too extreme for example if the longest half axis is a factor 100 longer than the shortest It is strongly advised to check the geometry with POSTFEKO Example of EL card usage The mesh shown in figure 9 14 is generated by using the EL card Figure 9
303. he directivity and equivalent aperture and gives an appropriate warning if this is not the case December 2005 FEKO User s Manual 10 40 DESCRIPTION OF THE CONTROL CARDS The permissible range of the angles J is 0 180 and they must be in ascending order Le 941 gt Y However the angles do not have to be equidistantly spaced Thus for example for a highly directive antenna a denser grid can be used close to the main beam direction The same applies to the angles yj where the permissible range is 0 360 For field angles outside the start and end values defined in the data i e for Y lt V4 0 gt Vmax P lt Y1 OF Y gt Pmax the field strengths ESF and E F are set to zero such that a sector radiator can be realised The values at field angles within the defined range are determined by bilinear interpolation To realise a complete radiation pattern rather than a sector radiator the angles should be defined such that J 0 Vmax 180 p 0 and Ymax 360 The radiation pattern specified in the local spherical coordinate system V vy of the antenna is read and initially placed at the origin of the global coordinate system in which the pre file is constructed The pattern is now rotated by an angle a around the z axis by a around the y axis and by a around the z axis The rotation is identical to the rotation executed by the TG card in section 9 2 38 and the rotation matrix M is applic
304. he magnetic field strengths for the Green s func tion of a layered sphere hfe File containing the magnetic field strengths Contains both the position and the complex components of the magnetic field strength vectors This file is only generated on request by a DA card section 10 2 24 inc Include file for PREFEKO isd Data file containing the field distribution calculated by FEKO for cou pling with CableMod or PCBMod log Log file created by OPTFEKO lud File in which the elements of the LU decomposed MoM matrix are stored only generated on request of a PS card section 10 2 39 mat File in which the matrix elements of the linear equation system are stored only generated on request of a PS card see section 10 2 39 nas NASTRAN geometry file which can be imported with the IN card neu Geometrical data file which is exported by the program FEMAP opt Input file for the program OPTFEKO EM Software 4 Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 21 ofc Paging files for the array elements used with sequential and parallel out of core solution To avoid the 2 GByte file size limit or on parallel systems with a distributed file system several files may be used These are distinguished by adding numbers to the filename 0S File containing the surface currents and the currents in the segments Data is in the form of position and the complex components of the current density vectors
305. he maximum of all the components of the gradient at the current point The iteration terminates if all the components of the gradient are smaller than this value Search step length ALAM ALAM designates the dynamic length of the search step in the line search similar to the increment factor LAMBDA in the line search used in Brent s method see the Conjugate Gradient method A Newton step is executed at the start of every line search In the immediate vicinity of a minimum this leads to quadratic convergence when ALAM is set to 1 0 The factor for EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 11 ALAM should only be changed in exceptional cases variational procedures With further search steps within a line search ALAM is determined first by quadratic then by cubic approximation Scale factor STPMX The factor for STPMX is used to scale the aim function should it become necessary to limit the maximum step width during a line search This avoids evaluating the aim function at points where it could overflow or where it has not been defined At the start of the optimisation process an internal factor is calculated from the STPMX variable and the components of the start vector This is then used to scale all further calculations on aim vector in a similar manner If at the beginning of a line search the square root of the sum of the squared components the absolute value of the aim vector is lar
306. heck this item to include quadrangles The quadrangles are subdivided into triangles along the shortest diagonal during im portation Include polygons Check this item to include polygonal plates for UTD Include node points Check this item to include node points Include only node points for imported triangles and or wires If this item is checked only the node points which are used by the imported elements are imported This is useful if one imports for example a few seg ments from a file containing a large number of triangles With this option one may then only import the points associated with the segments even if they have the same label as the ones associated with triangles only Label selection Most options allow label selective importing How the various layers properties names are converted to FEKO labels is dis cussed separately for each import option One may Include all items Include items with only a single label or Include items with range of labels If the first option is selected all elements are im ported irrespective of label If the single label option is selected the Include structures with field becomes active Specify the label as it will be after conversion in this field If the range option is selected the Up to field also becomes active All elements with the label larger or equal to the first and smaller or equal to the second field are included If the import option does not support l
307. hen the second FE card is run Thus the first frequency pass is finished At the next frequency pass the cards FE SK and FE are read again but the losses from the SK card are still active from the first pass The SK card is thus useless and the two FE cards calculate the same things twice The correct input order is December 2005 FEKO User s Manual DESCRIPTION OF THE CONTROL CARDS FR SK FE SK FE EN FR card for multiple frequencies skin effect switched off calculation of the near fields skin effect switched on calculation of the near fields end of the input file Then the four cards SK FE SK and FE are calculated for all the frequencies EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 5 10 2 Detailed description of the control cards 10 2 1 card The comment lines discussed in section 9 2 1 can also be used after the EG card December 2005 FEKO User s Manual 10 6 DESCRIPTION OF THE CONTROL CARDS 10 2 2 Ax Cards This card defines the type of excitation as well as other parameters regarding the excita tion The following possibilities are available Card Type of Excitation AO A linear polarised plane wave incident on the structure At Excitation by means of a voltage gap on a segment i e impressed electric field strength along a segment A2 Excitation by means of a voltage gap at a node i e between two segments A3 Excitation by
308. here must lie in the same plane EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 59 9 2 23 KR card This card creates a mesh of surface triangles in the shape of circular region with or without a hole It is also possible to distort it to an elliptical region Parameters S1 S2 93 S4 The angle vy KR Specify a circular section Ea si 3 Sa s2 S 3 J s4 The angle Y degrees Poo Maximum edge length outer o Maximum edge length inner lt Scale second half axis with The centre point of the circle A point that is situated at any distance perpendicular to and above the plane of the circle A point on the outer arc If there is a value present for this parameter then a circular ring is created S4 must lie between S1 and S3 The angle subtended by the arc in degrees Maximum edge length outer The maximum edge length of the triangles along the outer edge of the arc in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Maximum edge length inner When a disk with a hole is created the maximum edge Scale second half axis length for the triangles along the inner edge of the arc in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used If this parameter is empty or is set to 1 a circular disk is cre ated If set
309. hing of parallel FEKO processes By default both the installation script and the parallel launcher will use the remote shell for this purpose remsh under HP UX and rsh for all other UNIX platforms A typical setup is then to use a rhosts file see detailed comments given during the installation But this is not quite secure and one might prefer to rather use the secure shell ssh in connection with public key authenti cation avoids having to type passwords all the time The actual remote shell executable e g rsh or remsh or ssh will be determined during the installation procedure and the environment variable FEKO_RSH will be set to point to this executable This can always be changed later e g us ing rsh for the installation as root but then ssh for the users using the parallel FEKO version or vice versa by changing the value of the environment variable FEKO_RSH in the FEKO initialisation file initfeko or initfeko csh accordingly One can also set this on a user per user ba sis then directly for instance in profile after having executed initfeko This environment variable will not be used on Windows systems FEKO_TMPDIR This variable specifies the directory where FEKO will write paging files when using the out of core solution In the past it was required that the definition ended in a backslash Windows or a slash UNIX This is no longer required For example in UNIX it may be set with set FEKO_TMPDIR tmp export FE
310. his is global and can be positioned anywhere However since it is a geometry card it must be before the EG card If Modify all dimension related values is unchecked the following is scaled Coordinates of the corner points of the triangular surface elements e Coordinates of the corner points of the segments e Radii of the segments e Coordinates of the corner points of the cuboids e Radii of the all the layers when the Green s function for a homogeneous or layered dielectric sphere is used GF card section 10 2 30 e Thickness of the layers when the Green s function for a planar multilayered sub strate is used GF card section 10 2 30 e Coordinates of the corner points of the polygonal plates e Coordinates radii and dimensions of UTD cylinders EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 89 Coordinates of the corner points of tetrahedral volume elements Thickness of dielectric surface elements SK card section 10 2 42 Radius and thickness of a wire coating CO card section 10 2 23 Coordinates of wedges and edges in the PO region Coordinates of the Fock region Transmission line length and end point coordinates TL card section 10 2 44 The dimensions of the aperture used in the AP card and the amplitudes of the A5 and A6 dipoles which depend on the incremental areas The variable Maximum identical distance specified with the EG card section 9 2 12 whic
311. his option to save or read the matrix elements of the system of linear equations This is typically not recommended since the file will be large and the time to recompute the ma trix elements is typically much shorter than the time for the LU decomposition of the matrix Save read LU decomposed matrix Select this option to save or read the LU decomposition of the system of linear equations This option is useful if you want to solve a problem subsequently with multiple different excitations i e right hand sides Note that if you do this in one FEKO run i e one pre file then FEKO keeps the LU decomposition au tomatically in memory This option is useful if you want to solve for multiple excitations in different FEKO runs Save read currents Select this option to save or read the the solution vector of the system of linear equations The solution vector corresponds to the currents on the structure being simulated December 2005 FEKO User s Manual 10 104 DESCRIPTION OF THE CONTROL CARDS FEKO always uses the most efficient computation when doing multiple solutions in one file However sometimes one might also do a solution look at the results and then change certain parameters Then the option to store the solution in the str file and load it again or the similar option for the LU decomposition are particularly useful The option to save the currents is applicable when the solution stays the same i e same geometry
312. hod e RGMRES Parallel Iterative Method e RGMRESEV Parallel terative Method e RCGR Parallel Iterative Method e CGNR Parallel Iterative Method e CGNE Parallel Iterative Method e QMR Parallel Iterative Method e TFQMR Parallel Iterative Method e Parallel LU decomposition ScaLAPACK routines Paral lel LU decomposition with ScaLAPACK solution in main memory or with out of core ScaLAPACK solution with the matrix stored on hard disk This is the default option for parallel solutions and normally the user need not change it e MR QMRPACK routines e Direct sparse solver Direct solution method for the FEM no preconditioning Mazimum number of iterations The number of iterations limit for the iterative techniques Stopping criterium for residuum Termination criterion for the normalised residue when using iterative methods Terminate with convergence when the normalised residue is smaller than this value Stop at maximum residuum For parallel iterative methods the solution is terminated when the residuum becomes larger than this value Terminate with divergence when the normalised residue is larger than this value Preconditioners In this list the preconditioner is selected from e No preconditioning No preconditioning is used e Scaling the matrix A Scaling the matrix A so that the elements on the main diagonal are all normalised to one December 2005 FEKO User s Manual 10 60 DESCRIPTION OF
313. howing 6 7 spherical modes 10 43 voltage on a node 10 13 voltage on a segment 10 12 voltage on an edge 10 21 10 26 waveguide modes 10 51 SP card 10 117 specified vertex 4 38 spheres 4 18 9 62 dielectric magnetic 9 17 spherical modes 10 43 spinning parts 4 26 spiral 9 31 spirals 4 21 splines 4 21 split parts 4 26 status bar 4 3 STL file 9 48 stripline feeding 10 26 loading 10 92 substrate 10 86 subtract 4 26 superuser mode in EDITFEKO 5 6 surface currents distribution 10 101 surface triangles see elements surfaces 4 19 4 31 creating solids 4 26 metal 4 33 suspect 4 23 sweeping parts 4 26 SY card 9 90 symbolic variables 7 2 symmetry 2 10 4 48 9 90 electric 2 11 geometric 2 10 magnetic 2 11 tetrahedral volume elements 9 81 tetrahedron definition 2 3 TG card 9 91 thin dielectric sheet 10 111 TIMEFEKO 12 1 TL card 10 118 TO card 9 94 tolerance 4 41 toolbars 3D view 4 9 POSTFEKO 6 2 selection 4 3 4 35 showing 4 3 standard 4 4 toroidal segment 9 94 TP card 9 96 transformation 4 24 6 6 9 91 of point 9 96 workplane 4 8 translation 4 24 9 91 9 96 transmission lines 10 118 coupling 10 23 10 62 showing 6 7 tree 4 11 showing 4 3 triangles see elements back side 4 44 creating 4 44 normal side 4 44 normals 4 44 remove duplicates 4 42 U axis 4 6 4 16 unconnected edges 4 33 4 43 undo list depth 4 46 meshing 4 4 model
314. ibute to the impedance The LD card may be combined with the LP LS LZ and the SK cards but only one LD card may be used per label If a second LD card is used it replaces the values entered by the first one This card has no significance for surface elements even when these are assigned the same label EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 95 10 2 33 LE card With the LE card an edge between surface triangles can be loaded with an impedance Z R jX as shown in figure 10 24 LE Load an edge between triangles Load edge between regions with two labels Load an edge connected to ground UTD Load microstrip edge between two points Label of triangles on one side of edge Label on second side of edge Imaginary part of impedance Real part of impedance See the AE card for the excitation of such an edge As shown in figure 10 24 the edge can consist of several single edges each of which should be common to triangles that have one of only two labels One of these labels must be unique i e only one triangle at each single edge should have this label See the AE card section 10 2 12 for a discussion of the allowed configurations Alternatively the edge can be along a connection between triangles and a polygonal UTD plate or a PEC ground plane or it can be a microstrip feed line port The impedance Z applies to the complete edge i
315. ied normalisation of the spherical modes the unit of this amplitude is VW VV A Phase of the mode The phase of the complex amplitude of this spherical mode in degrees Source position The position of the origin r 0 of the mode in m These values are optionally scaled by the SF card The implementation of the spherical modes at the AS card follows closely the references J E Hansen Spherical Near Field Antenna Measurements Peter Peregrinus Ltd London 1988 and B C Brock Using Vector Spherical Harmonics to Compute Antenna Mutual Impedance from Measured or Computed Fields Sandia National Laboratories Report SAND2000 2217 Revised April 2001 One must realise that Hansen assumes a complex time dependence of e while FEKO always uses the positive sign e t In FEKO using the modal coefficients QSmn the electric and magnetic field strength is represented in a spherical coordinate system by S 2 ow n z E Ready EF Y 0 c 3 s 1 n 1 m n 4 4 2 00 n A z H r p 2 2 2 2 QG F m nlr p 0 Here s m and n are the mode indices with s 1 indicating the TE mode and s 2 the TM mode see also the discussion above and c represents the propagation direction c 3 is inward and c 4 is outward The term Zp denotes the wave impedance of the medium under consideration 3 below is the corresponding wavenumber The spherical wave functions F ta are given by Fiond p Minn 8 4 8 Ta 1 0 er jm sin 0
316. iew The POSTFEKO layout is similar to that of CADFEKO and EDITFEKO At the very top is the title bar and menu The dockable main toolbar is by default located just below the menu The control panel located on the left of the display area controls the display of the active window This panel contains different pages that control different aspects of the view The different pages are accessed with a vertical row of buttons on the left side of the control panel and where multiple pages are allowed with the tabs at the top of the pages APOSTFEKO C FEKO users horn pfs File View Options Run Windows Help g ere Info La els lle sO la lt Seeofeal CEO heta 11 33 Phi 37 90 dh Figure 6 1 The main POSTFEKO display Here only the geometry of a single model is displayed and the control panel is showing the model information The Control toolbar is the left part of the main toolbar and controls session information and storage These functions are also available under the File menu EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 3 Jb EGES6bh ee 1 2 z s 5 6 7 3 1 New session closes the current session and unloads all loaded model files and opens a new blank session 2 Open session closes the current session and unloads all loaded model files and loads an existing session 3 Save session saves the current session for future use
317. ified once For the global parameters the values of the last PO card will be used Using Full ray tracing illumination only from outside has two main applications e Acceleration of the PO ray tracing with closed bodies the normal vector must then point outward since the dot product of the normal and propagation vectors can be EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 79 used to quickly determine if a triangle or polygon is to be used in the ray tracing In this case the closed model must be constructed with the normals pointing outward e In for example the MoM PO hybrid method on a closed body the MoM region such as an antenna can be prevented from illuminating the PO region from inside A basis function that has been assigned to an edge between two triangles will only be solved with the PO if the PO approximation has been declared for the labels of both triangles The metallic PO region must be perfectly conducting i e no losses are allowed Dielectric coatings see CO card and thin dielectric sheets see SK card can however be treated with the PO approximation December 2005 FEKO User s Manual 9 80 DESCRIPTION OF THE GEOMETRY CARDS 9 2 32 PY card This card defines by specifying the corner points a polygonal surface to which the UTD formulation is applied PY Specify a polygonal plate Specify corner nodes of the polygon Points are c
318. ilarly VS cards 9 and 10 states that label 3 is not visible to itself and fully visible to label 4 Finally we must consider the case for triangles with label 4 All visibility with layers 0 to 3 has been specified and may not be specified again Unlike the previous flat plates layer 4 is curved and some triangles may indeed illuminate other triangles with the same layer However not all other triangles will be illuminated this is only possible for a doubly concave surface such that we cannot specify any information for label 4 December 2005 FEKO User s Manual 9 104 DESCRIPTION OF THE GEOMETRY CARDS 9 2 44 WG card With this card a wire grid in the shape of a parallelogram can be generated Parameters S1 82 53 S4 No a wires on the outside edges WG Creates a wire grid parallelogram si sa s saj C Yes Length ofthe grid gaps The four corners of the parallelogram in consecutive order Generate wires on the outside edges If the No item is selected only the wires inside the parallelogram are generated whereas if the Yes item is selected all the wires are generated This option is important when two adjacent parallelograms are generated as the segments along the sides must not be generated twice Length of the grid gaps The maximum segment length is given by the IP card This parameter is an integer number and specifies the density of the grid If for example
319. imaginary part of the target impedance Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read December 2005 FEKO User s Manual 11 20 THE OPTIMISER OPTFEKO Min reflection coefficient Select this to use the option to limit values that have a sufficiently good match to avoid that these are optimised further rather than focusing on the optimisation of other impedance values with a worse match The minimum value should be entered below this box The assignment of the aim function in the opt file is selected using the keyword IMPEDANCE or IMPEDANZ The error function is defined as Li Zsoll fi Li Z soll If the Min reflection coefficient option is used an additional value for the minimum reflection coefficient PIB in dB is specified The modified algorithm to compute the aim function is as follows For all impedance values 1 1 Ng define the reflection coefficient Li mE Zso T ll Li F Zsoll raB and then truncate to Tmin 10720 i e the corresponding linear desired reflection coef ficient in the aim function fi max Tj Dinin The reason for doing this is to avoid that one impedance value such as one port or the impedance at one frequency which has already an acceptable match is being optimised further and further instead of focusing on the optimisation of other impedance values where the desired match has not yet been o
320. inated by a line of the form next spaces are allowed between and next but not before the All instructions and input cards between for and next are evaluated repeatedly inside the loop e Several loops can be nested as shown in the example below EM Software 4 Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREFEKO 7 9 A more complicated example illustrating some of the points above is as follows end 3 sin 4 for x1 sqrt 5 2 3 to 2 end step end 10 for x2 1 23 to 2 x1 this is the inner loop x3 Hx1 x2 DP gesa more commands next Inext 7 5 IF ELSE ENDIF constructs This construct is used to allow different control cards under different conditions The syntax requirements of IF ELSE ENDIF constructs are e The characters must be located in the first two columns of the line This is followed by an arbitrary number of spaces the expression to evaluate evaluated and the keyword then it is not case sensitive THEN or Then are also accepted e The block is terminated by a line of the form endif again spaces are allowed between and endif but not before the e An optional line of the form else again the must be in the first two columns and spaces are allowed before the keyword which is not case sensitive e All instructions and input cards between if and endif or else if it is present are processed if the expression is TRUE If it is presen
321. inear with the amplitude of the excitation this extra degree of freedom can be removed by activating an optional normalisation of the near fields with respect to one point whose amplitude after normalisation will then be one and then phase will be zero But one can also optimise for absolute field strength values in V m electric field or A m magnetic field Aim function op Aim 1 Select aim function Near field values Weighting factor fi Near field Electric C Magnetic Both Treatment for multiple blocks Averaging over the blocks Take maximum minimax principle Number of blocks Lines per block Field strength normalisation M Normalisation Index of value Component Component 4 9o 9 e il Ou fe Weighting factors Iv Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions Near field Optimisation of electric fields magnetic fields or both can be selected here EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 25 Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read Lines per block The number of samples to r
322. ing of labels is to read a label mapping table from an external file This file consists of an abitrary number of lines old_label new_label i e the old and new label entries separated by the character Some external meshing programs can for instance export a NASTRAN file along with such a mapping table and then by using the two commands IN 3 3 geometry nas CB geometry txt one can get the model into FEKO with the proper names of the parts i e the file geometry txt would then do a proper mapping of the NASTRAN property to the part name in the original CAD programme December 2005 FEKO User s Manual 9 14 DESCRIPTION OF THE GEOMETRY CARDS 9 2 7 CL card This card is used to create an arc consisting of wire segments CL Arc of wire segments Se gt Zi a s2 3 3 J Subtended angle degrees J Maximum length of segments J IV Set tapered wire radius Radius at start point of wire J Radius at end point of wire J Scale second half axis with Parameters Si The centre point of the circle S2 A point perpendicular to the plane in which the circle lies and above its centre 53 The start point of the arc Subtended angle yp The direction of the subtended angle is in the positive sense around the axis S1 83 A negative value will create the arc in the opposite direction Maximum length of The maximum length of the segments that make up the arc If this field is left empty
323. inning of the file the value in this field should be set equal to 1 This parameter is used when the ffe file contains more than one pattern For example if the file contains the pattern at various frequencies the correct pattern can be selected by setting this field to the appropriate value for each frequency Number of 0 points The number of Y angles in the pattern Number of p points The number of y angles in the pattern The radiation pattern of the antenna must be specified in spherical coordinates V y with the phase centre located at the origin of the local coordinates as used in the pattern data If this is not the case the phase of the far fields will not be correct For example if a ffe file is exported with FEKO to be used with the AR card the origin should be shifted with the OF card to the phase centre of the antenna The vertical and horizontal components of the complex electric field Ef and or ESF must be specified at discrete angles 9 pj with and j larger or equal to 1 and smaller or equal to the number of points specified for the respective angles The field values are entered in Volts and the actual far fields are calculated from with R the distance to the field point and P the complex propagation constant in the free space medium see the EG and GF cards These formulas are used for all distances R i e also in the near field However FEKO tests whether the far field conditions are met by calculating t
324. input file and write a isd file for CableMod processing The only parameter of this card is the file name of a rsd file created by CableMod or PCBMod enclosed in double quotation marks and starting at or after column 91 The rsd file contains geometry of the line With the CM card FEKO calculates the electric and magnetic near field at points along the line and write these to a isd file for further processing by CableMod or PCBMod The isd file also contains additional data required by CableMod or PCBMod for example the frequencies that were used during the solution The complete geometry without the transmission line as well as the frequency and excitation Ax cards must be defined in FEKO 9To use this the CableMod PCBMod module must be activated if required please contact your distributor EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 63 10 2 23 CO card This card specifies a dielectric or magnetic coating of wire segments or triangular surface elements The coating applies to all calculations following the CO card CO Specify dielectricimagnetic coating CO Specify dielectricimagnetic coating Labels of elements to coat Labels of elements to coat pos C No coating as if CO card not present C No coating as if CO card not present C Wire coating Popovic formulation C Wire coating Popovic formulation Wire coating Volume equiva
325. ins the subdirectories such as bin doc license and for the parallel version mpi If this environment variable is set to 1 then FEKO runs for 30 days in the un registered FEKO LITE mode FEKO is then restricted regarding the element sizes etc but does not need a licence see the Getting started manual for more details The parallel version of FEKO is started by running RUN FEKO with options np x When FEKO is installed on a parallel computer or a computer cluster the configuration of the cluster and the number of processes that should be run on each computer is specified during the installation This can be overwritten for any FEKO run by creating a so called machines file and setting the environment vari able FEKO_MACHFILE to point to this file More detail can be found in section 8 2 If this parameter is set FEKO will write information about the machine precision to both the screen and the output file EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 23 FEKO_MAXALLOCM This environment variable is used to limit memory in MByte that FEKO is allowed to use on this computer This environment variable is not needed or recommended for computers running Windows or Linux operating sys tems On others the variable is set at installation time The value of this variable should usually be set equal to the physical memory minus 70 MBytes for the operating system In a few cases a lower limit may
326. ins two labels Face1 for the triangles on the plate and Wire5 for the segments on the monopole The bottom segment can now be selected and its label changed to Feed In EDITFEKO this segment can now be referenced by its full label Union1 Feed in any field expecting labels Relabelling may also be used to reduce the number of labels in any given part When the last element of any label is removed deleted or relabelled the label is removed Care must be taken when remeshing parts where the mesh has been relabelled Since the entire mesh part is replaced by the new mesh the label created by relabelling the elements is lost If the example above is remeshed there will again be only the labels Facel and Wire5 Therefore relabelling elements should be delayed as much as possible Another option is to break the monopole in two in such a way that the bottom wire will always mesh into only one segment but then the geometry must be modified before generating a new mesh with a different size 4 13 3 Transforming mesh parts Mesh parts can be transformed similarly to geometry parts see section 4 7 1 The transform applies to the entire part and can be edited or removed If a vertex of a transformed mesh is edited the transformed coordinates are displayed and user input is assumed to be in the transformed space If the transform is modified the effect is also applied to the edited vertex 4 13 4 Merging coincident vertices Connectivity in FEKO
327. int 72 For both cases FEKO automatically searches for all the triangles making electrical contact with the Amplitude Phase x y z coordinate end point Current amplitude in A at the Start 71 and End T2 points Phase of the current at the start point in degrees Coordinates of the start and end points in m Note that all the coordinate values are optionally scaled by the SF card Radius of impressed current This parameter is optional If specified and different from zero this value gives a finite wire radius for the impressed cur rent element FEKO then assumes that the current is uniformly December 2005 FEKO User s Manual DESCRIPTION OF THE CONTROL CARDS 10 50 distributed on the wire surface and uses the exact wire integral If the parameter is not specified the current filament approximation is used This value is optionally scaled by the SF card The following restrictions apply when using the impressed current elements making elec trical contact with conducting surfaces e All the restrictions given in the discussion of the AI card also apply in this case e The start point of the impressed current segment may be connected with AI cards or further AV cards If there is a current discontinuity at this point the resulting point charge is not considered see the discussion given with the AI card Line charges along the current path and surface charges on the triangles are correctly taken int
328. ion Order q of Bezier curve in v direction The order of the B zier curve in the direction Both p and q must be in the range from 1 to 4 where 1 is linear 2 quadratic and so on The control points are entered in the table more or less representing their physical relation There are p 1 rows and q 1 columns It is possible to create a triangular Nurbs surface In this case all control points on one side must be identical use the same point The weights of the control points are specified at the DP card Note that for higher order B zier curves the surface does not pass through the control points except those on the corners Examples of NU card usage The saddle point shape in figure 9 26 and the linear quadratic shape in figure 9 27 are generated with NU cards using 4 and 6 control points respectively NURBS may also be used to generate flat surfaces with curved edges The section of a circular plate with a square hole in figure 9 28 is generated using a NU cards EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 69 Z BB Figure 9 26 Saddle point example using the NU card from demo_NU1 pre AB BB Figure 9 27 Linear quadratic example using the NU card from demo_NU2 pre Figure 9 28 A flat surface with curved edges created with an NU card in demo_NU3 pre December 2005 FEKO User s Manual 9 70 DESCRIPTION OF THE GEOMETRY CARDS
329. ion lines ending at one wire are connected in parallel December 2005 FEKO User s Manual 10 120 DESCRIPTION OF THE CONTROL CARDS Any load impedance defined over the transmission line port segments with the LZ LS LP LD CO or SK cards are placed in series with the port parallel admittances can be defined directly at the TL card If a voltage source of type Al or A3 is applied at one of the port segments then this voltage source is assumed to be across the port i e feeding the transmission line directly with an impressed voltage Any other sources are in series with the port FEKO automatically determines the type of the transmission line network 1 no impressed voltage source at both ports 2 impressed voltage source at the input port 3 impressed voltage source at the output port 4 impressed voltage source at both ports The wire segments for the two ports should be located in the same medium so that the propagation constant of this medium can be taken for the transmission line If the segments are in different media then the medium of the segment at the input port is used Note that the propagation constant and thus also the propagation loss of the transmission line is the same as that of the medium surrounding input port unless an additional loss factor is specified in the Losses field If this is free space the transmission line will be lossless For transmission lines with a propagation constant that is higher than that of
330. ion specified by this parameter is added to any losses of this medium This factor is not affected by scaling specified with the SF card i e if a scaling factor which reduces the length of the transmission line is added the total loss through the line will be less The length is now less and the loss per distance remained the same Real part of Zo Real part of the characteristic impedance of the transmission line in Ohm Imaginary part of Zo Imaginary part of the characteristic impedance of the transmis sion line in Ohm Note that the characteristic impedance only defines the ratio between the voltage and current of the two waves propagating along the line It does not specify any losses Real part of shunt Y at port 1 Real part of the shunt admittance at the input port in Siemens This admittance is across the port connecting the two wires of the transmission line Imaginary part of shunt Y at port 1 Imaginary part of the shunt admittance at the input port in Siemens Real part of shunt Y at port 2 Real part of the shunt admittance at the output port in Siemens This admittance is across the port connecting the two wires of the transmission line Imaginary part of shunt Y at port 2 Imaginary part of the shunt admittance at the output port in Siemens An arbitrary number of transmission lines can be used also one wire segment could be for instance the end of one transmission line and the start of another All transmiss
331. ion time For example for an SK card the whole matrix has to be recalculated while an Ax card only redefines the right hand side of the matrix A summary of the dependencies is given in the table below Action For the cards recalculates matrix elements BO CF CO DI FR GF L4 LD LE LP LS LZ SK SP TL recalculates the right hand side Ax BO DI FR GF resolves the matrix equation CG There are also other dependencies If the matrix elements are recomputed then the matrix equation has to be solved again The actual calculation is started by the CM FE FF OS SA and SP cards All other cards are read and the data stored When solving for a number of frequencies all the control cards following the FR card up to but excluding the next FR card or EN card are read into a buffer For each frequency all these cards are read and processed The computation time can be reduced significantly by using the cards in the correct order If for example a structure needs to be investigated at two frequencies and with two different excitations then the control cards can be organised in either of the following ways FR FR card for the two frequencies Ax first excitation Ax second excitation EN end of the input file or EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 3 FR FR card for the two frequencies Ax first excitation FR FR card for the two frequencies Ax second excitation EN
332. is not as apparent in the 3D view pressing lt Shift gt while selecting will merely add remove the new item In the tree navigation can also be done with the arrow keys This includes pressing lt Shift gt to select multiple items All selected items must be of the same type i e it is impossible to select a part and some of its faces at the same time However simultaneously selecting faces belonging to different parts is allowed If the lt Ctrl gt key is pressed while right clicking to activate a pop up menu the current selection will be left unaltered If lt Shift gt is pressed the new item will be added to the selection if it is not selected but it will not be removed if it is selected Selection in the 3D view is controlled with the Selection toolbar This contains two sets of toggle buttons and undo and redo buttons for the selection In each toggle set one button is always on active The toolbar looks as follows RARAS wa RA Single Polygon Faces Mesh Mesh View Redo parts elements mesh edges selection Rectangle Geometry Edges Mesh Mesh Undo parts labels vertices selection The three how to select buttons enable specification of how items will be selected If the first Single select is toggled on down items are selected by clicking on them If Rectangle select is toggled on a rectangle is defined by clicking at one corner and then moving the mouse with the mouse button up to the o
333. is only important when used with the Physical Optics PO card or with dielectrics ME card or for the CFTE CF card EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 9 Examples of BQ card usage The BQ card can be used to create the mesh shown in figure 9 6 or also for inhomogeneous meshing as shown in figure 9 7 Figure 9 6 Example of a BQ card from demo_BQ1 pre Figure 9 7 Example of a BQ card with an inhomogeneous segmentation from demo_BQ3 pre December 2005 FEKO User s Manual 9 10 DESCRIPTION OF THE GEOMETRY CARDS 9 2 5 BT card A mesh of surface triangles in the shape of a flat triangle can be created with this card In general this card is replaced by the PM card BT Specify a triangle 3 si b a 2 J ae A s FF Specify non uniform meshing Mesh size along side b Mesh size along side c Mesh size along side a Parameters S1 S2 53 The points S1 to S3 are the three corner points of the triangle These points should have been defined previously with the DP card Specify non uniform Normally a triangle is segmented according to the edge length specified with the IP card In some cases it may be desirable to use a finer segmentation in one direction Check this item if finer segmentation is required along any edg
334. is possible Move all points starting from label together with ending at label specify the label range of points that must be translated rotated or scaled See the general discussion of label ranges in section 2 3 If the second field is left empty only structures with the label set in the first field are considered Label increment for moved points Each transformed point will be assigned a label that is the label of the original point incremented by this value The exception are points with label 0 their label is not incremented it remains 0 Rotation around the x axis Angle of rotation a around the x axis in degrees Rotation around the y axis Angle of rotation a around the y axis in degrees Rotation around the z axis Angle of rotation az around the z axis in degrees Translation along the x axis Translation Az in the x direction All three translation dis tances are affected by the scaling factor set with the SF card Translation along the y axis Translation Ay in the y direction EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 97 Translation along the z axis Translation A in the z direction Scaling in In this group the user may choose whether scaling is in the x direction y direction or z direction or a combination of these Scale factor The scaling factor y with which the point is scaled after rotation and translation if the parameter R7 is not specified i
335. is selected only the edges of the model is shown This allows viewing hidden objects but can be a very confusing display Since only the edges are displayed cylinders will look the same as two disks and spheres are completely invisible The Edit workplane Transform workplane and Specify cutplanes buttons provide quick access to these functions The Vertical Z axis button controls the rotation of the model in such a way that the Z axis remains vertical on the screen i e locking it in place The next two buttons zoom to the full model extent or to a selected window respectively To zoom to a window after clicking this button click and drag the mouse without releasing the button to define the window The Restore default view button resets the view angles to the standard position December 2005 FEKO User s Manual 4 10 WORKING IN CADFEKO The Undo view action and Redo view action buttons also accessed with the short cut keys lt Alt gt lt lt gt and lt Alt gt lt gt apply to all view manipulations in the current view View manipulations are remembered in a separate list from the one used to store model manipulations so that view operations can be undone separately from geometry modi fications The Undo Redo buttons are disabled if there are no additional undo redo operations 4 3 5 Cutplanes Right click on the 3D view and select Cutplanes to open the cutplane dialog for that view or click the Specify cutplan
336. is used and that this card requests a continuous frequency band The variable adaptfreq is defined automatically at the start of the single frequency input files and this variable may be used to allow for example adaptive meshing One should not directly assign this variable inside the pre file as this will overwrite the value specified by ADAPTFEKO at the top of the file If one needs this variable for example to run PREFEKO during model setup when using adaptive meshing one may use the DEFINED function 11if not defined adaptfreq then adaptfreq 250 0E6 lendif December 2005 FEKO User s Manual 13 2 THE PROGRAM ADAPTFEKO 13 4 ADAPTFEKO example As an example we will consider the input impedance of a simple forked dipole shown in figure 13 1 The input file forked_dipole pre is as follows this file is located in the examples utils adaptfeko subdirectory of the FEKO installation Forked dipole antenna Full MoM solution with adaptive frequency sampling Frequency for the discretisation lam cO 3 0e8 Segmentation parameters IP lam 1000 lam 20 Define some points DP Pi 0 01 0 0 5 DP P2 0 0 0 01 DP P3 0 01 0 0 466 DP P4 0 0 0 01 Half of the wire LA 0 BL Pi P2 BL P2 P3 Symmetry SY 1 0 0 1 The feed segment LA 1 BL P2 P4 End of geometry EG 1 0 0 0 0 Excitation A1 0 1 1 0 Adaptive frequency band FR 2 100 0e6 300 0e6 EM Software amp Sy
337. isualisation window which displays a single model has focus the OUT file of the associated model is opened Otherwise POSTFEKO will prompt for a model Note that the OUT file listing is not updated automatically when the OUT file changes The viewer must be closed and reopened to update it 6 9 Advanced troubleshooting features 6 9 1 Database browser The database browser is used to list and control the models in the current session It is not shown by default and can be activated by selecting View Database browser from December 2005 FEKO User s Manual 6 18 WORKING IN POSTFEKO the menu It lists the data that was calculated for each model in the session as well as which data is currently cached in memory Files can be removed and or unloaded by right clicking on them and selecting the appropriate action from the pop up menu 6 9 2 Help menu The Getting started manual and User s manual can be opened from the Help menu These are PDF documents which requires that a valid PDF viewer is specified on the Options Settings dialog EM Software 4 Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREFEKO 7 1 7 The preprocessor PREFEKO 7 1 Description The surface of the structure to be analysed with the program FEKO has to be subdi vided into elementary surfaces in this case triangles Wires have to be subdivided into segments The mesh size is dependent on the wavelength in the medium surrounding the
338. ith or without modification are permitted provided that the following conditions are met 1 Redistributions of source code must retain the above copyright notice December 2005 FEKO User s Manual 15 2 COPYRIGHT NOTICES AND ACKNOWLEDGEMENTS this list of conditions and the following disclaimer 2 Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution 3 Neither the name of Lawrence Berkeley National Laboratory U S Dept of Energy nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF
339. ize is specified on for example an edge of a surface then the triangles of the surface honour this length along the edge even though the rest of the surface may have a much larger mesh size The Mesh size growth factor controls how quickly the mesh size changes Fast allows an abrupt jump from small to large elements while for Slow each triangle will not be more than twice the size of the one it is connected to The mesh is a snapshot of the current geometry Any changes to the geometry for example changing a wire radius made after meshing will not be reflected in the mesh The mesh is listed in the tree under Meshes with the same structure as the original geometry parts The meshes are identified by their labels only When meshing the geometry Cuboid1 CADFEKO will give a warning if a mesh with such a label already exists The existing mesh may be kept or replaced If the mesh or geometry is renamed before trying to remesh the geometry an additional mesh part is created See also section 4 13 2 4 12 1 Specifying mesh parameters When regions faces or edges are selected local mesh parameters can be specified by selecting Properties from the pop up menu In all three cases the properties dialog includes a Mesh size group as illustrated at the top of the Edge properties dialog in figure 4 21 For regions the local mesh size is only used when meshing the region into tetrahedra The final mesh size on any item is the minimum of all sizes a
340. ked out components POSTFEKO 1 CADFEKO 1 97 2005 09 30 5 0 Platinum Unlimited tH 198 2005 09 30 5 0 Platinum Unlimited ri 190 20 19 32 RAM Platini ira I llimitad Figure 3 2 The licence manager with a typical floating licence 3 2 1 Preferred licence When a new licence is requested the floating licence server will check out the first available licence Where users have multiple licences they may not necessarily be identical Some licences may for example be memory limited GUI licences or the CableMod PCBMod module may be activated only in some licences In this case the first available licence may not be the desired one The licence server thus supports a preferred licence Right click on any licence and select Mark as preferred from the pop up menu The preferred licence is listed at the top right of the licence manager When the user next requests a new licence this one will be used The preferred licence can also be selected by clicking on the licence and selecting Server Set preferred licence from the main menu Click the Clear button or select Server Clear preferred licence from the main menu to remove the preferred licence Since the server will just use the first available licence if the preferred licence is already in use there is very little need for an individual user to clear his preferred licence However if your company has one full and a number of limited GUI licences you should not check out the full
341. label selected calculation 10 100 labels 2 8 4 34 9 12 9 64 changing 4 41 using 4 41 4 47 LD card 10 94 LE card 10 95 licence 3 1 floating 3 2 information 3 1 preferred 3 3 server 3 3 line 4 21 line segments see segments linear set of equations 10 58 load data in POSTFEKO 6 15 loaded files POSTFEKO 6 17 loading 10 118 an edge 10 95 attachment point 10 92 distributed 10 94 impedance 10 99 microstrip line 10 95 parallel circuit 10 97 series circuit 10 98 showing 6 7 local coordinates 4 16 4 46 local mesh parameters 4 38 lock point entry 4 18 loft 4 27 losses 10 105 LP card 10 97 LS card 10 98 LZ card 10 99 machine codes 3 4 magnetic cuboids 9 17 magnetic dipole 10 19 magnetic fields calculating 10 71 magnetic ring current 10 14 manual online 4 49 maxalloc m 2 16 15 maximum constants 2 16 2 17 ME card 9 65 medium dielectric 4 31 9 65 9 81 9 82 imported models 4 31 magnetic 9 81 9 82 properties 4 47 memory allocation 2 16 menu pop up 4 5 4 13 view 4 4 merging vertices 4 41 mesh 4 36 adding triangles 4 44 edit vertex 4 44 element selection 4 36 import 4 39 information 4 40 local settings 4 38 properties 4 45 show hide parts 4 10 mesh refinement 9 84 meshing 2 2 non uniform 9 6 9 8 9 10 rules 2 5 message window 4 3 metal on dielectric 4 33 MFIE 10 56 mirror 4 24 MLFMM 9 27 modelling rules 2 2 models 4 5 modify ge
342. lanar Green s function is used in FEKO then also spatial peak average SAR values can be computed not volume average SAR A selection is possible by a single layer number a range of layer numbers or by including the whole dielectric volume in the search EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 111 10 2 42 SK card This card is used to consider the Skin effect or ohmic losses or an arbitrary user defined impedance boundary condition on wire segments and surface elements In addition it can switch from metallic triangles to thin dielectric layers which may consist of multiple layers and which may be anisotropic If no SK card has been defined FEKO assumes ideal conductivity without any losses 10 2 42 1 Skin effect and ohmic losses SK Add a skin effect finite conductivity Affect all structures with label ss C Assume ideal conductivity High frequency approximation skin effect Static approximation skin effect Exact expression for the skin effect Triangles as thin isotropic dielectric sheet Triangles as thin anisotropic dielectric sheet User defined surface impedance Thickness of elements Po Conductivity Sim NT Relative permeability Aj Magnetic loss factor tan 8 Parameters Affect all structures with label Affect all segments and triangles with this label Assume ideal conductivity Ideal conductivity is assumed also the default when the
343. ld keep in mind that the RM card can only do a mesh refinement and no mesh coarsening i e as soon as for larger distances the remeshing option exceeds the already used mesh size of the original model simply nothing will happen Although not required it is often useful to set the mesh size s2 identical to the global already existing mesh size then the parameter da readily controls the region where a local mesh refinement is desired i e for distances d larger than da the original mesh will be kept It shall also be mentioned here that if a CableMod rsd file is imported in order to evaluate distance d between each mesh element and the cable harness in the right base EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 87 unit if an SF card scaling factor is set this can be for instance mm the cable harness coordinates have to be scaled accordingly Thus the SF scaling factor must be known before the RM card can be used PREFEKO will give an error if an SF card is read and a RM card was processed before The user must then just move the SF card in front of the RM card in the pre file Examples of RM card usage A first example is shown in figure 9 38 with the original mesh on the left hand side and on the right hand side the result of a local mesh refinement with respect to a point is given For the example in figure 9 39 a local mesh refinement with respect to two lines is used i e two simul
344. le degrees 360 Semi infinite cylinder Semi infinite cylinder S1 side end cap S2 side end cap S1 side end cap S2 side end cap Parameters Sl The start point of the cylinder axis S2 The end point of the cylinder axis 53 A point on the radius of the cylinder the angle S2 S1 S3 must be 90 The angle vy The angle of the cylinder segment Currently this must be 360 Select a flat end cap or a semi infinite end on the side of S1 Select a flat end cap or a semi infinite end on the side of S2 Example of UZ card usage The cylinder in figure 9 42 was created using a UZ card Note the absence of discretisation Figure 9 42 Example for UZ card from demo_UZ1 pre EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 101 9 2 43 VS card This card specifies known visibility information required when using physical optics with multiple reflections to reduce the time required to calculate it VS Set visibility for the PO Triangles labelled J are le visible from notvisible from IV specify range of triangle labels triangles with label to triangles with label L To accurately compute multiple reflections the code needs to determine which basis func tions are visible to each other Since this applies to all the PO triangles it may be very time consuming for large problems The time required to determine the visibility
345. le direction is obtained see note above Rel permittivity The relative dielectric constant r of this layer in the Principle and Orthogonal directions respectively Conductivity The conductivity o in 5 of this layer in the Principle and Orthogonal directions respectively Loss factor The loss tangent tan tan E of this layer in the Principle and Orthogonal directions respectively December 2005 FEKO User s Manual 10 116 DESCRIPTION OF THE CONTROL CARDS 10 2 42 4 User defined surface impedance SK Add a skin effect finite conductivity Affect all structures with label Assume ideal conductivity High frequency approximation skin effect C Static approximation skin effect C Exact expression for the skin effect C Triangles as thin isotropic dielectric sheet C Triangles as thin anisotropic dielectric sheet User defined surface impedance Impedance in Ohm triangles or Ohmim wires Real part Imaginary part With this option an arbitrary user defined complex surface impedance Zg can be used in FEKO It must be noted that the impedance boundary condition for the MoM also then for MLFMM etc has certain limitations regarding the range of validity FEKO uses whatever the user has specified as surface impedance and it is the responsibility of the user to ensure that the application of an IBC is still warranted for the specific configuration dependent on the impedanc
346. le to place it right after the EG card EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 105 10 2 40 PW card When defining the excitation of an antenna the source is normally specified as a complex voltage The PW card allows the user to specify the radiated power or the source power instead FEKO then just internally scales the whole solution to arrive at this desired power In addition it is possible to consider a mismatch between the antenna input impedance and the internal impedance of a voltage source or the characteristic impedance of a transmission line feed PW Specify the source power Scale power to the value given below C No scaling use specified voltages Total source power no internal impedance Total source power internal impedance C Total source power transmission line feed I Decouple all sources when calculating power Selecting this may compromise accuracy Source power Natt Source impedance real part Source impedance imag part Parameters No scaling use specified voltages PW card is not activated i e the specified value of the voltage source is used Total source power no internal impedance PW card is activated and all the currents are multiplied by a scaling factor such that the total source power the sum of the power delivered by all the individual sources is Po the value specified in the Source power field Mi
347. lements 5177 max tetrah MAXNTETRA 5177 Number of edges in PO region 0 max edges MAXPOKA 0 Number of wedges in PO region 0 max wedges MAXPOKL 0 Number of Fock regions 0 max Fock reg MAXFOGE 0 Number of polygonal surfaces 0 max surfaces MAXPOLYF 0 max corner p MAXPOLYP 0 Number of UTD cylinders 0 Number of metallic edges MoM O unknown O max edges MAXNKA 93 Number of metallic edges PO O unknown 0 electr O magnet Number of dielectric edges MoM 0 unknown 0 electr 0 O magnet Number of dielectric edges P0 0 unknown 0 electr O magnet Number of edges FEM MoM surface 93 unknown 93 electr 93 93 magnet Number of nodes between segments 36 unknown 36 max nodes MAXNKNO 66 Number of connection points O unknown 0 max conn MAXNV 0 Number of dielectric cuboids O unknown O max cuboids MAXNQUA 0 Number of magnetic cuboids O unknown 0 EM Software amp Systems S A Pty Ltd December 2005 12 15 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 7 Number of basis funct for MoM 36 unknown 36 max basisf MAXNZEILE 86 Number of basis funct for PO O unknown O max basisf MAXNKAPO 0 Memory requirement for MoM matrix 144 rows 222 columns 31968 complex numbers For the matrix a memory of 31968 complex numbers is available i e 499 5 kByte Here the data e g the number of basis functions on the nodes between segments can be extracted It is also i
348. lems Note that all the modes inwards and outwards propagating are correctly included when doing a near field computation with the FE card also for very large distances As an application example we consider the TE mode n 5 and m 0 and compute the far field pattern Create the far field radiation pattern of a spherical mode No geometry EG 1 0 0 0 0 Set the frequency FR 1 100e6 Spherical mode indices s 1 1 TE mode 2 TM mode n 5 mode order n with n 1 2 3 tm 0 mode order m with m n n 2K Excitation AS 0 4 s m n 1 0 ko Compute the full far field pattern FF 1 91 37 0 0 0 2 10 End EN The resulting pattern is shown in figure 10 15 From the FEKO output file one can see the correct radiated power of 0 5 Watt as obtained from the far field integration December 2005 FEKO User s Manual 10 48 DESCRIPTION OF THE CONTROL CARDS Integration of the normal component of the Poynting vector in the angular grid DTHETA 2 00 deg and DPHI 10 00 deg 3367 sample points angular range THETA angular range PHI radiated power 1 00 181 00 deg 5 00 365 00 deg 5 13889E 01 Watt 0 00 180 00 deg 0 00 360 00 deg 5 00001E 01 Watt Figure 10 15 3D radiation pattern of a spherical TE mode with n 5 and m 0 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 49 10 2 17 AV card With this two line
349. lence principle C Wire coating Volume equivalence principle C Electrically thin surface coating Electrically thin surface coating C Dielectric magnetic surface coating C Dielectric magnetic surface coating Thickness of coating o Relative permeability o i e Relative permittivity amp Conductivity Sim of 2 Magnetic loss factor tan 6 o Dielectric loss factor tan 6 aa i a Wire radius Layer 1 Thickness of layer Relative permeability gt iz Relative permittivity 7 Conductivity Sim a Magnetic loss factor tand f Dielectric loss factor tan 7 4 H Parameters Label of elements to coat All segments or triangles with this label are coated No coating No coating present as if the relevant label has no CO card This is used to remove wire coatings from earlier solutions Wire coating Popovic formulation In this case the radius of the metallic core is changed internally to model the change in the capacitive loading of the wire and a corresponding inductive loading is added The only restriction of this method is that the loss tangents of the wire coating and of the surrounding medium must be identical for instance both media could be lossless Wire coating volume equivalence principle Here the radius of the metallic wire is re tained The effect of the dielectric layer is accounted for by a volume polarisation current The only restriction of this method is that the layer may not b
350. les to the wavelength squared 4 gt do a gt in Ratio of the cuboid edge length to the wavelength gt 0 25 t gt 0 5 Ratio of the cuboid edge length to the skin depth l gt 5 A gt 3 Ratio of the tetrahedral face area to the wavelength squared inner mesh elements 4 gt 0 047 4 gt 0 433 Ratio of the tetrahedral face area to the wavelength squared boundary surface mesh elements gt 0 033 gt 0 108 EM Software 4 Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 5 2 2 3 Meshing guidelines regarding connectivity The segmentation or meshing is performed automatically by CADFEKO or PREFEKO or also a combination of the two for mixed models or if for instance mesh refinement is used with the RM card There are some rules that must be adhered to for the final mesh Most of these rules are automatically complied with when creating FEKO models in CADFEKO However users must take care of these rules when for instance combining CADFEKO and PREFEKO models e g attaching an antenna modelled with geometry cards on an aircraft meshed in CADFEKO or when creating the geometry solely in PREFEKO Wires can only be connected at the end points of the respective segments They are not allowed to overlap An example is shown in figure 2 1 When using geometry cards then the wires AB and CD are not allowed to be entered in this way AB will be subdivided into segments so that point C is not r
351. lex impedance Label of segments to load J Real part of impedance Ohm J Imaginary part Ohm Parameters Label of segments All segments with this label are assigned the specified impedance Real part of impedance The real part of the complex impedance in 2 Imaginary part The imaginary part value of the complex impedance in Q The complex impedance value is a constant with respect to frequency Frequency depen dent impedances can be realised using the LS or the LP cards The LZ card may be combined with the LD LP LS and the SK cards but only one LZ card may be used per label If a second LZ card is used it replaces the values entered by the first one This card has no significance for surface elements even when these are assigned the same label December 2005 FEKO User s Manual 10 100 DESCRIPTION OF THE CONTROL CARDS 10 2 37 OF card This card specifies an offset for the origin of the coordinate system used for near and far field calculations In addition it is possible to use only a part of the structure when calculating the fields selected using labels OF Options for field calculations I Calculate near field or far field on offset axis FF Use only some labels for field calculation Start at label End at label Origin of offset coordinate Parameters Calculate near field on offset axis Use the offset specified below as the origin of the coor dinate system for field calcul
352. ll be calculated The far field points are shown on a finite radius to facilitate comparison with the model orientation 6 All the options relating to the display of excitations in the 3D view are controlled from the Show Excitations page The Set refers to a collection of sources that are active at any given time and the Source field facilitates selecting individual sources from the set Note that sources are counted with respect to how many are being displayed If a model has four sources for some calculations and four more sources the first thereof a specified as a new source are added for further calculations the sources in the second set will be numbered 5 to 8 when All is selected under set but they will be 1 to 4 when just viewing the second set If a single source is selected its amplitude and magnitude are displayed near the top of the page For some sources it is possible to display the sources coloured according to their amplitude For these cases it is also possible to put a legend at any of the four corners Four legends can be used simultaneously EM Software amp Systems S A Pty Ltd December 2005 WORKING IN POSTFEKO 6 7 Setting the AI AV A5 A6 length controls the length of the impressed currents dipole elements on the display If the AI AV sections are reduced the it is much easier to distinguish the individual sections 7 The Show loading and Transmission lines page controls the viewing of loads a
353. ll dipoles in the aperture The aperture is based on the equivalence principle This states that the sources and scatterers inside a given volume can be removed and modelled by placing the equivalent currents J x H and M x Eon the enclosing surface The vector is a unit vector normal to the surface and points towards the exterior region The fields in this region are the same as the original fields while those in interior region are zero Field values are read from the data files with a possible offset specified with Start from point number or the pre input file and converted to equivalent electric magnetic fields and magnetic electric field dipoles at these points Note that all angles are read from the data but no distance values Thus for planar apertures the positions are calculated entirely from the specified points S1 S2 and S3 For cylindrical apertures S1 and S2 specify the extents of the aperture along the local 2 direction and S1 S3 specifies the direction of the x axis as well as the radius of the cylinder The points are placed at the values listed together with the field data For spherical apertures S1 S2 specifies the direction of the z axis and S1 83 the x axis S2 and S3 must lie on the same radius which is also the radius of the field points In this case both Y and y are read with the data EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 33 Fig
354. locks are required Under normal circumstances these variables should not be set they could have a negative impact on the FEKO performance maxaeedges The maximum number of edges between triangles that may be excited with the AE card maxanr The maximum number of sources maxapo The size of the memory block that is used to save the coefficients in the physical optics approximation For maxapo 0 the necessary amount will be dynamically allocated maxarang The maximum number of Y or y angles used with the AR card ex citation by a point source with a specified radiation pattern maxarpat The maximum number of radiation pattern excitations AR card allowed simultaneously maxbsobnr To accelerate the ray path search with PO the area under consid eration is divided into boxes Information pertaining to which box contains which object must be stored A field of size maxbsobnr is used in this case December 2005 FEKO User s Manual 2 18 GENERAL COMMENTS maxcolayer The maximum number of layers on a CO card which implements thin dielectric sheets maxdrnv The maximum number of triangle elements that can be connected to a segment at an attachment point maxfepkts The maximum number of points considered for the near field compu tation with the FE card when using Specified points maxfoge The maximum number of areas that are described by using the Fock theory maxgfmsia The maximum number of entries in
355. low DP Define an input point Point name A X coordinate 0 0 Y coordinate 0 0 Z coordinate h Nurb control point weight Y ox x Cancel Add December 2005 FEKO User s Manual 5 8 THE EDITOR EDITFEKO When a card editor dialog is selected from either the button panel or the menu there is a button to Add card This adds the card without closing this dialog This is useful when defining a number of similar cards for example when specifying the first group of DP cards at the start of a model Often only one or two parameters differ between cards Clicking OK adds the card and closes the editor dialog Pressing lt Enter gt has the same effect as clicking on the OK button Similarly lt Esc gt closes the card editor dialog without adding the card as if the Cancel button has been clicked In the card editor dialogs moving the mouse pointer over the labels may give more information of the specific input field If the user is uncertain about the meaning or units of a given field it is always advisable to move the mouse pointer to the label to determine if any additional information is available All the input fields in FEKO have a fixed length In the card editor dialogs it is not possible to enter longer strings than allowed for the particular field If the field contains the maximum number of characters no new keys are excepted Then it is necessary to delete characters before any additional ones can be en
356. lt Ctrl gt lt Ins gt Copy selected text lt Shift gt lt Del gt Cut selected text December 2005 FEKO User s Manual 4 50 WORKING IN CADFEKO lt Ctrl gt lt A gt Select all items of the current selection type object face edge mesh element etc lt Ctrl gt lt C gt Copy selected text lt Ctrl gt lt K gt Create new root level parts from copies of all selected items lt Ctrl gt lt M gt Create mesh lt Ctrl gt lt N gt Create new model lt Ctrl gt lt 3 gt Create new 3D view lt Ctrl gt lt O gt Open model lt Ctrl gt lt Q gt Select snap option only if a 3D view has focus lt Ctrl gt lt S gt Save model lt Ctrl gt lt V gt Paste lt Ctrl gt lt X gt Cut selected text only in the notes editor lt Ctrl gt lt Y gt Redo model creation modification lt Ctrl gt lt Z gt Undo model creation modification lt Alt gt lt gt Undo view manipulation lt Alt gt lt gt Redo view manipulation EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 1 5 The editor EDITFEKO A PREFEKO input file is a standard ASCII text file that may be created with any available text editor The model geometry and desired calculations are entered through lines of text referred to as cards The complete geometry can be build in CADFEKO and imported using one of these cards Each card may have a number of parameters which must appear in fixed positions The editor ED
357. m and n with s 1 for TE modes s 2 for TM modes m N N andn 1 N see also more detailed description at the AS card in section 10 2 16 including a one dimensional compressed indexing scheme j 1 J and the normalisation of the modes etc The input parameter Maximum mode index N determines the maximum mode index N i e a total number of J 2N N 2 modes will be computed The modes origin is the same as for the far field computation in general i e this is the global origin unless an OF card has been used to specify an offset It should also just be mentioned that due to the nature of the far field propagating towards r oo all computed mode coefficients refer to spherical cylinder functions Zk with type c 4 see more details at the AS card It shall be mentioned that when spherical modes are computed with the FF card the DA card can also be used must be in front of the FF card in order to request that this spherical mode expansion is exported to an SWE file extension sph which can be imported into the computer code GRASP from TICRA GRASP is a reflector antenna modelling code and by means of this SWE file export one can for instance model a horn antenna as feed in FEKO and then export this feed structure and use in GRASP The spherical mode expansion coefficients Qsmn as used by FEKO are described at the AS card in section 10 2 16 In GRASP a slightly different convention is used e An additional factor Te is use
358. m an external data file See further details below Old label All the structures with this label are relabelled New label The new label for all the structures with the old label Filename The name of the file used when reading the label list from an external data file Renaming labels is especially useful when more labels are created by using symmetry SY card or transformations TG card or an imported geometry from CADFEKO and for example edges or wedges in the PO area are considered or any other properties shall be set by label e g Skin effect Structures created after the CB card are not affected In order to make the renaming of a whole set of different labels simpler the Old label field in the CB card is also supporting wildcards an arbitrary sequence of characters and a single arbitrary character So for instance to rename all these labels Cube Facel Cube Face2 Cube Face3 Cube Face4 Cube Faceb Cube Face6 to a new label CubeSurface one could use six CB cards but with the wildcards this is much simpler to use just one CB card and specify the old label as EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 13 Cube Face or also as Cube depending on what other labels are also in the model Note that such wildcards are only supported in the Old label field of the CB card The New label must be unique Another possibility to do a bulk renam
359. m functions into global aim functions Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read For each block 1 Ng the first row is read and the gain directivity gi in dB is extracted The local aim function is given by fi g The minus sign ensures that a minimisation of the aim function maximises the gain This aim function is selected by using the keyword GAIN or GEWINN in the opt file December 2005 FEKO User s Manual 11 14 THE OPTIMISER OPTFEKO Isotropic radiators This aim function allows the user to design an antenna with the best possible isotropic gain Here one can optimise for more than one frequency by using the frequency blocks from the output file from FEKO in the aim function Aim function c Aim 1 Selectaimfunction isotropicradiators Weighting factor A Components Theta LHC cs C Phi RHC Treatment for multiple blocks Averaging over the blocks Take maximum minimax principle Number of blocks Rows per block IV Include default comments Weighting factor This factor specifies the relative weight of this aim function as compared to additional aim functions Components The components of the far field that should be isotropic Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functio
360. m label layer The selected SAR calculation is obtained for the medium label specified in the Include medium label dia log Average Peak SAR in a medium label layer range The selected SAR calculation is per formed on the label range as specified below in the input fields for Include medium label and up to medium label Centre of SAR cube For the spatial average SAR computations using a specified po sition the X Y and Z coordinates of the cube centre must be specified here December 2005 FEKO User s Manual 10 110 DESCRIPTION OF THE CONTROL CARDS The required SAR calculation is performed and the result saved in the out file If the options Calculate volume average SAR and Entire region are selected the SAR averaged over all media is returned If the options Calculate volume average SAR and By medium are selected the average SAR is calculated per medium and tabled in the out file If a medium label layer range is specified the SAR is averaged over the volume defined by the medium label layer range If a spatial peak SAR calculation is requested then spatial peak SAR is computed av eraged over a mass of either 1 g or 10 g of tissue in the shape of a cube By default the search for the spatial peak SAR in the entire domain is returned otherwise the spatial peak SAR can be requested for regions in a specified medium label layer range or also at a user specified position When a special spherical or multilayer p
361. m within the Run menu This is shown in figure 8 2 Enter the hostname or IP adress of the remote host in the input field Remote host in the example in figure 8 2 this hostname is server In order to then actually also use the remote launching click in the Run menu on Remote FEKO execution so that this gets checked Then any subsequent runs of the FEKO solver either sequential or parallel if Parallel FEKO execution is also checked until this Remote FEKO execution gets un checked again will be launched remotely on the remote host In order to use this remote launching facility from the command line the command runfeko example_08 remote host h can be used where the parameter h following remote host gives the hostname or the IP address of the remote host This command line option of RUNFEKO can be combined with other options for instance using runfeko example_08 remote host h np 4 machines file m would launch a parallel job with 4 processes using the nodes as listed in the machines file m and the parallel job is then launched from the remote host h which is typically some control node of a cluster As mentioned initially the remote launching facility has an automatic file transfer in cluded so it is not necessary to work on some kind of shared network drive On the remote host FEKO will in the user s home directory create a temporary sub directory with the name remote_FEKO_job_xxx xxx is a unique number and all the FEKO
362. may be greatly reduced if the user can inform the code that certain triangles are hidden from each other and others are visible to each other Parameters Triangles labelled The label of the source triangles are visible from All triangles with the label specified in the field Triangles labelled are visible from all triangles with label s indicated in the fields below are not visible from All triangles with the label specified in the field Triangles labelled are not visible from all triangles with label s indicated in the fields below specify range of labels If this item is unchecked only a single label is specified in the field triangles with label If checked the card applies to all triangles with labels in the range from the value specified in the triangles with label field to that in the to triangles with label field Note that visibility is reciprocal i e if all triangles with label n are visible from all triangles with label m all triangles with label m are visible from all triangles with label n as well Basis functions cannot illuminate each other if all the triangles they are attached to lie in the same plane The VS card should only be used if the user can specify the visibility beyond any doubt and if it applies to all triangles of that label If no information is specified for a specific combination of labels triangles full ray tracing will be executed Example of VS card usage December 2005 FEKO User
363. mber of Memory Solution Time Unknowns usage in seconds Symmetry not used 792 9 74 MByte 24 8 All 3 coordinate planes declared as 792 9 74 MByte 22 1 planes of geometric symmetry Plane x 0 declared as electric plane 198 2 56 MByte 8 9 of symmetry plane y 0 as magnetic plane of symmetry and plane z 0 as geometric plane of symmetry This example has relatively few unknowns Most of the computational time is therefore used to determine the matrix elements in comparison to the time taken to solve the matrix equation For applications with more unknowns the reduction of unknowns could make a considerable difference in the time and memory required 2 4 5 Special enforcement of symmetry Even odd method The table in the previous section demonstrates the advantage of using electric and or magnetic symmetry For very large structures which have only geometrical symmetry it may be worthwhile to consider two separate problems with electrical and magnetic symmetry as described below Figure 2 12 a shows the original problem It consists of a dipole antenna with a passive wire below it This is admittedly a very simple problem normally this procedure would only be applied to much more complex structures The structure in figure 2 12 is symmetric about the plane z 0 but the excitation is asymmetric and thus only geometric symmetry can be applied in FEKO This problem may be separated into the two sub problems shown in figure
364. means of a magnetic ring current TEM Frill on a segment Thus a coaxial feed can be modelled A4 Special vertical pin excitation e g for a patch antenna on a planar substrate with a ground plane coaxial probe excitation mode A5 A Hertzian dipole is used as excitation The position and orien tation in the space are arbitrary A6 A Magnetic dipole is used as excitation The position and orien tation in the space are arbitrary A7 Excitation by means of a voltage gap on an edge between two triangles This card has been generally replaced by the AE card AC This card reads the geometry and current distribution possibly for more than one frequency from an rsd file created by the transmission line simulation program CableMod or by the PCB simulation tool PCBMod or by export with the OS card in FEKO The excitation is due to the electromagnetic fields radiated by these line currents AE The AE card is an excitation between triangle edges similar to the AT card however the AE card permits the simultaneous excitation of several edges AI Excitation by an impressed line current AP Excitation with an aperture array of electrical and magnetic Hertzian dipoles AR Excitation by an antenna with a given radiation pattern AS Excitation by means of incident of radiating spherical modes AV Excitation by an impressed line current similar to the Al card but the endpoint of the current is electrically connected to a con ductin
365. meters as an arbitrary function of frequency inside a frequency loop which is not possible with the EG card Note that switching to single precision currently does not have any effect on the MoM PO or UTD These will always use double precision irrespective of the switch This might change in future Presently switching to single precision only has an effect for the MLFMM multilevel fast multipole method and the FEM finite element solution EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 25 9 2 13 EL card A mesh of surface triangles in the shape of an ellipsoidal section can be created with this card EL Specify an ellipsoid section sf s2J sa sa Begin angle da degrees ft Begin angle a degrees i End angle e degrees ss End angle Y e degrees ls Maximum triangle edge length lJ Parameters S1 The centre point of the ellipsoid S2 A point in the direction Y 0 in elliptical coordinates The distance of the two points S1 and S2 determines the half axis of the ellipsoid in this direction S3 A point in the direction Y 90 y 0 in elliptical coordinates The distance of the two points S1 and S3 determines half of the axis of the ellipsoid in this direction S4 A point in the direction of the third coordinate i e the axes S4 S1 S3 S1 and S2 S1 must be perpendicular The distance of the two points S1 and S4 determines half of t
366. mined as the distance between the origin of the local coordinate system and the projection of the point in the local UV plane To specify a sharp tipped cone leave the Top radius field O New solids are metal by default but can be changed to dielectric or shell structures This is done by setting region properties see section 4 8 4 6 5 Creating surface primitives All 2D surfaces are created as solid sheets They therefore also contain a Face entry in the tree In this document surfaces refer to parts or components Faces refer to individual sheets making up the surface or defining the boundary of a solid Currently only flat polygons elliptical disks and paraboloid surfaces are supported December 2005 FEKO User s Manual 4 20 WORKING IN CADFEKO Polygons are created with the dialog shown in figure 4 6 All the specified points must lie in a plane the simplest option is to align the local coordinates with the plane of the polygon and ensure that all N coordinate values are zero A Create polygon 2 x Geometry Local Properties TF Use global coordinates Comer 1 Add Remove Reverse normal Label Polygon1 Figure 4 6 The dialog used to create polygons Clicking Add adds an additional corner after the one that has focus or if no corner has focus at the end of the list The polygon is created by connecting the lines in the specified order and the edges are not allowed to cross The cor
367. models then have no regions and it is not possible to specify dielectric properties However if surface parts are unioned to form closed surfaces CADFEKO automatically constructs the applicable regions for the new parts To set the medium parameters select one or more regions and select Properties from the pop up menu This opens the Region properties dialog as shown in figure 4 17 The Mesh size field allows defining a local mesh size see section 4 12 1 for tetrahedral meshing X Region properties 12 x Mesh size Y Local mesh size Mesh size 0 2 Medium Type Dielectric y Dielectric name Wood y Figure 4 17 The Region properties dialog The Type field is used to define the medium type it may be metallic dielectric or free space Free space indicates the surrounding background medium which may be a homogeneous dielectric but is usually free space Free space regions are hollow while metallic regions are solid The difference is mainly apparent during geometry operations The Dielectric option is only allowed if the Media list contains dielectrics as discussed above Dielectrics can be defined while the Region properties dialog is open the Dielectric option then becomes available immediately For dielectrics the Dielectric name must be selected from the list of available dielectrics This name is used with the DI card in EDITFEKO to set the medium parameters Unlike label names which must be
368. mp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 57 Figure 9 19 Example of a cone with different subtended angles at the top and bottom from demo _KK3 pre Figure 9 20 Example of a conical section where the start angle is not in the plane defined by S1 S1 and S3 demo_KK4 pre December 2005 FEKO User s Manual 9 58 DESCRIPTION OF THE GEOMETRY CARDS 9 2 22 KL card This card defines a wedge for which correction terms are added to the PO currents on the two surfaces connected to it Parameters Ky Ke Po Py KL Specify a PO region border wedge K1 poo K2 y Po Prf Label ofthe O side triangles Label of the N side triangles The start point of the edge of the wedge The end point of the edge of the wedge A point on the o side of the wedge A point on the n side of the wedge Label of the O side triangles The label of the PO triangles that are adjacent to the wedge on the o side This means that the corresponding correction term for the o side is assigned to the PO triangles that have this label Label of the N side triangles The label of the PO triangles that are adjacent to the wedge on the n side This means that the corresponding correction term for the n side is assigned to the PO triangles that have this label Note that the wedge must be between flat surfaces and that all triangles with the label specified
369. mponents Ez Ey and E in complex form In cylindrical coordinates the columns consist of the following r p 2 Er Ey and E In spherical coordinates the columns consist of the following r 0 P Er Eg Ey hfe file Same form as the efe file except that the magnetic field values are given ffe file Here the angles Y and y are given Following them are the field components Ey iBnR and E in complex form with the factor a left out as in the output file The gain separated into the polarisation directions or the radar cross section is given in dB See also detailed discussion of the far field quantities in section 14 6 os file First the triangle numbers and the centroids x y and z are given as well as the complex current densities Jz Jy and J at the centroid Then there are three values which give the absolute value of the current density at the three corner points as averaged over all triangles that are adjacent to the corner points The next three complex values are the components of the complex current density vector J for the first corner point of the triangle The following groups of three are the values for the second and third corner points of the triangles After the current values in the triangles the columns containing the data for the segments follow For each segment a segment number is given the centroid x y and z as well as the current I Iy and I flowing in the segment cgm file In this file the n
370. n have a significant effect For example if the U vector of the workplane is defined by snapping to some model point such as a mesh vertex the vector from the origin to this point is calculated and entered into the field as a numeric value If the origin is modified December 2005 FEKO User s Manual 4 18 WORKING IN CADFEKO afterwards the direction of the U vector remains unchanged If however the direction of the vector is specified by snapping to a named point it is re evaluated whenever the origin is changed The U vector then keeps pointing at the specified point Fields which accept multiple values from point entry have Lock buttons next to them If such a button is toggled on down that field is not updated when selecting a point This is used when there is a need for example to click on points in the workplane without modifying the value in the N direction It is also possible to specify different named points in the three component fields of a point Each component is then determined by projecting the specified point along the required dimension As values are entered into the fields an outline preview of the geometry is shown If lt Ctrl gt lt Shift gt is pressed while moving the mouse over the screen without clicking the fields values are updated continuously This is called Preview mode The active fields show the values that would be entered if the mouse was clicked at that position The values in the active fi
371. n some cases e g when cre ating small microstrip lines it may be desirable to use a finer segmentation in one direction Check this item if a finer segmen tation is required in one direction The mesh sizes are in m and are scaled by the SF card Mesh size along sides a and c Edges S1 82 and 3 S4 Mesh size along sides b and d Edges S2 83 and S4 S1 The points are connected in the order that they appear in the BP card Thus the user has to ensure that the points describe a parallelogram If this is not the case then PREFEKO will abort with the appropriate error message The direction of the normal vector fi of the subdivided triangles is determined by the right hand rule through all the corners This direction is only important when used with the Physical Optics PO card section 9 2 31 or with dielectrics ME card section 9 2 26 or with the CFIE CF card section 10 2 20 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 7 Example of BP card usage Figures figure 9 4 and figure 9 5 shows a plate with uniform meshing and a strip with non uniform meshing respectively both created with the BP card Figure 9 4 Example for the BP card from demo_BP1 pre Figure 9 5 Example of a BP card with non uniform meshing from demo_BP2 pre December 2005 FEKO User s Manual 9 8 DESCRIPTION OF THE GEOMETRY CARDS 9 2 4 BQ card A mesh of surface triangles i
372. n the shape of a flat quadrangle can be created with this card Models constructed using the BQ card can generally be simplified by using the PM card BQ Specify a quadrangle Spb sf 3 So s o P s d 5 F Specify non uniform meshing Mesh size along side a Mesh size along side b Mesh size along side c Mesh size along side d E Parameters S1 S2 S3 S4 The points S1 to S4 are the four corner points of the quadrangle These points should have been defined previously with the DP card Specify non uniform Normally a quadrangle is segmented according to the edge length specified with the IP card In some cases e g when creating small microstrip lines it may be desirable to use a finer segmentation in one direction Check this item if finer segmentation is required along any edge The mesh sizes are in m and are scaled by the SF card Mesh size along side a Edge S1 82 Mesh size along side b Edge S2 83 Mesh size along side c Edge S3 54 Mesh size along side d Edge S4 S1 The points have to be predefined using DP cards prior to the BQ card and are connected in the order that they appear in the BQ card In principal the BQ card can create all types of quadrangles including parallelograms The difference is that the BP card creates a regular subdivision The direction of the normal vector A of the subdivided triangles is determined by the right hand rule through all the corners This direction
373. nary output e g 6 956E 03 1 034539E 07 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 69 10 2 25 DI card Here the material characteristics of the dielectric and or magnetic bodies are entered using a medium number or index as set before at the ME card or as imported The DI card is used for the MoM MLFMM when using the surface current or volume current methods or also for the FEM DI Set dielectric properties Set properties for medium Po Relative permittivity lt BO Relative permeability 25 o Conductivity Sim NT Magnetic loss factor tan dj Dielectric loss factor tan JO Mass density ka m 3 yf Parameters Set properties for medium This gives the name of the medium as used in the ME card The name 0 number zero is reserved for the surrounding free space medium Relative permittivity Relative dielectric constant r of the medium specified in Set prop erties for medium number Relative permeability Relative permeability ur of the medium specified in Set properties for medium number Conductivity Conductivity o in az of the medium specified in Set properties for medium number Magnetic loss factor Magnetic loss tangent tan 6 of the medium specified in Set prop erties for medium number the complex permeability is then given by u pour 1 j tand Dielectric loss factor Electric loss tangent tan of the medium specified in
374. nction to assign a numerical value to the frequency variable freq in the pre this is useful for running PREFEKO and viewing the geometry in POSTFEKO see section 12 6 The FR card must use the frequency variable freq The number of frequencies to be examined must be one NFREQ 1 Example Set the frequency FR 1 freq In the input file pre all the desired output parameters in their respective cards must be set for example FF card FE card OS card Only the data in the output file out can be transformed Note The program TIMEFEKO does not check the pre file Special care should be taken to ensure that the segmentation parameters for the required frequency interval are fine enough for the program FEKO see IP card section 9 2 19 If they are not strictly adhered to the program can terminate with an error message 11The files have the same filename but with pre and tim extensions December 2005 FEKO User s Manual 12 2 THE PROGRAM TIMEFEKO It is also possible to vary the segmentation for certain applications far field near field to save memory and computation time To do this one may use the variable freq which is constantly changed by TIMEFEKO in the definition of the segmentation parameters Example Define some constants maxfreq 250 0e 08 minlambda cO maxfreq Define the edge length note the use of freq ttedgelen 2 0 freq maxfreq minlamdba 4 0 Se
375. nd transmission lines 8 The Find select elements page is used to locate elements with a specific number in the model Ranges of values can be entered For example to find all triangles numbered between 3 and 5 simply enter 3 5 in the text box next to triangles Additional searches can be performed by comma separating values The selection can be cleared by clicking on empty space or using the Clear button on this dialog This page works in conjunction with selection in the 3D view An object can be selected by clicking on it The data associated with the object is then displayed in the view and its element number is added to the appropriate list on the find menu 9 The Model information page shows information about the model This information helps to estimate the size of the solution 10 Cutplanes are used to hide the geometry on one side of the cutplane If a cutplane is Flipped the geometry on the other side of the cutplane is hidden POSTFEKO supports multiple cutplanes Clicking the Add button the green sign at the top of the panel adds an additional cutplane Clicking the Remove button the green sign removes the current one A cutplane can also be deactivated without removing it completely by unchecking the Active check box The Show all and Hide all buttons activate deactivate this Active check box on all cutplanes Arbitrary planes are specified with the Y and y angles of the direction normal to the plane It is
376. ndicated how many have the status unknown i e how many have to be determined by solving the matrix equation 14 2 Excitation The data here is structured depending on the means of excitation For a voltage source on a segment the following data block is generated EXCITATION BY VOLTAGE SOURCE AT SEGMENT Number of voltage source N 1 Frequency in Hz FREQ 7 50000E 07 Wavelength in m LAMBDA 3 99723E 00 Open circuit voltage in V UO 1 00000E 00 Phase in deg ARG UO 0 00 Source at segment w label ULA 1 Absolute number of segment UNR 11 If an incident plane wave is used then the output file has the following format EXCITATION BY PLANE LINEAR POLARISED ELECTROMAGNETIC WAVE Number of excitation N 1 Frequency in Hz Wavelength in m LAMBDA Direction of incidence THETA Dir of polarisation ETA Direction of propag BETAOX BETAOY BETAOZ Field strength in V m EOX Phase in deg EOY EOZ FREQ 1 9467E 07 1 5400E 01 180 00 PHI 00 0 00 1 6736E 10 0 0000E 00 4 0800E 01 1 00000E 00 ARG EOX 0 00 0 00000E 00 ARG EOY 0 00 4 1021E 10 ARG EOZ 0 00 The vector B whose components are given is the vector which points in the direction of propagation The vector Eq represents the direction of the electric field December 2005 FEKO User s Manual 14 8 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 3 Currents and charges The OS card can request the current distrib
377. ndicates that the new direction is determined using the approximation of the inverse Hesse matrix according to the DFP formula while the parameter 2 indicates the use of the BFGS formula to accomplish the same task The two methods to determine the new direction differ only slightly in their effect on the total process for example in rounding and convergence errors It has however been shown that the BFGS variant is sensitive to non optimal line searches December 2005 FEKO User s Manual 11 12 THE OPTIMISER OPTFEKO Delta for all variables DELTA establishes the dx for the calculation of the gradient single or double sided and allows a separate dx for every vari able according to the assumed sensitivity of the aim function for this variable The check box on the left can be checked if OPT FEKO should use the same value of Delta for all variables If a different value should be used the values should be entered in the table below The keyword used for this method is QUASI_NEWTON_VERFAHREN or QUASI_NEWTON_METHOD 11 2 5 Defining the aim function A number of different aim functions are available in OPTFEKO These aim functions represent typical electromagnetic parameters that need to be optimised such as radiation patterns and input impedance The aim function specifies the desired response from the model to be optimised Data from different blocks due to frequency change etc can be combined within an
378. ner with focus is shown with a blue square in the 3D display If the last coordinate is entered with the mouse CADFEKO automatically adds another point and moves the focus to it The Reverse normal button reorders the points in such a way that the normal vector determined in a mathematically positive sense from the direction of the edge is reversed When Create is clicked all empty points are removed automatically For polygons the Properties tab contains an entry Unmeshed plate If this is set to true the polygon is meshed into a single polygonal plate rather than into triangles This is then used with the UTD in FEKO The Label field allows entering the name of the new object This is visible in the tree and can be changed at any time The radii fields for the ellipse and the paraboloid primitives must be positive EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 21 The paraboloid is oriented along the N axis as shown in figure 4 7 The Radius field specifies the radius R in the plane orthogonal to the axis and must be positive The Focal depth is the distance f from the origin to the focal point If this is negative the paraboloid is oriented along the N axis The focal depth is related to the height h by R2 T Figure 4 7 Dimensions of a paraboloid 4 6 6 Creating curve primitives Curve parts in CADFEKO can be used either as building blocks for constructing geometry for example using th
379. ness d A good conductivity is required i e o gt wep For wires a further condition requires that skin lt o where o is the wire radius 1 ive 2710 g For metallic surfaces the condition skin lt g must be met The surface im pedance is given by Zs 4 i e Static approximation skin effect The required parameters are ur tan d and g and for surfaces also the thickness d A good conductivity is required i e o gt wep The surface impedance is given by Z For wires a further condition requires that skin gt o where o is the wire radius The surface impedance is given by Z L For metallic surfaces the condition skin gt g must be met The surface im pedance is given by Z 2 e Exact expression for the skin effect The required parameters are 4r tan and g and for surfaces also the thickness d A good conductivity is required i e o gt wep For wires with radius o the surface impedance is given by ge 1 j Jo 1 j fel 2reobskin Jy 1 j z Oskin where Jo and J are Bessel functions For metallic surfaces the surface impedance is given by 1 j 1 20 skin tan 1 7 5 Ls Examples are given in example_02 and example_33 in the Examples Guide EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 113 10 2 42 2 Triangles as a thin isotropic dielectric sheet SK Add a skin effect fi
380. ng that the properties are correct or have been corrected the faces may be reset using Set not suspect from the pop up menu The parametric capability in CADFEKO see section 4 5 makes it possible to edit the components of complex geometry operations at any time In most cases it may be quite difficult to identify which component to change CADFEKO therefore displays a wire frame representation of all selected parent items December 2005 FEKO User s Manual 4 24 WORKING IN CADFEKO 4 7 1 Transformations Geometry objects can be transformed by selecting them and selecting Edit Transform from the main menu or using the transform buttons on the Modify geometry toolbar The Transforms entry in the details tree contains a list in creation order of all the operations applied to each object These may be edited by double clicking on the specific operation or deleted by pressing the lt Del gt key A transform may be applied to a selection of multiple objects but it will be added separately to each object Therefore changing them afterwards requires selecting and editing the transform of each object separately The transform can of course be defined in terms of variables In this case changing the variable will modify all the items The Rotate operation requires an axis of rotation which is determined by an origin and an axis direction both in global coordinates and a rotation angle in degrees The angle is measured in a m
381. ng the FEKO solution to which power Pa is transferred EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 107 e Total source power no internal impedance Using this option all the source power is delivered to the respective antennas i e Poss Pay as shown in figure 10 27 To ensure that the total power is Po the power must be scaled with the factor Po Po N YN Pow v 1 v Mz Faw 1 The currents on the structure are consequently scaled with the factor y s There is no power loss e Total source power internal impedance When this option is used the internal impedance Z of the voltage source is con sidered as shown in figure 10 27 Since the same current flows through the internal source impedance and the antenna input impedance the power dissipated in the impedance of the v voltage source is given by the relation FS Na ReZayv and the scaling factor s to scale the total power supplied by the sources to Pp is Po Po Po Ne DF Pow Pay 1 H Mz Mz Pav Pi 1 v 1 y Il x Il The combined loss caused by the mismatched antennas N N Posa g 2 Fi s 2 Paw E reduces for example the antenna gain but not the directivity e Total source power transmission line feed When this option is used each antenna with input impedance Za is considered to be excited by a transmission line with a complex characteristic impedance
382. nite conductivity Affect all structures with label J Assume ideal conductivity High frequency approximation skin effect C Static approximation skin effect C Exact expression for the skin effect Triangles as thin isotropic dielectric sheet C Triangles as thin anisotropic dielectric sheet User defined surface impedance Relative permeability A Magnetic loss factor tan 64 Number of layers Layer 1 Thickness of elements Relative permittivity amp J Conductivity Sim o J Dielectric loss factor tan Y Parameters Relative permeability The relative permeability ur which is the same for all layers Magnetic loss factor Magnetic loss tangent tan 6 the complex permeability is then H opr 1 j tan a which is the same for all layers Number of layers The number of layers If this field is empty or 0 it defaults to 1 Thickness of elements The thickness d of the current layer in m if an SF card is present this is always scaled Relative dielectric constant The relative dielectric constant r of the current layer _ Conductivity The conductivity o in gg of the current layer a WEQEr Electric loss factor The loss tangent tan tan of the current layer This option only makes sense for triangular surfaces not for wires The required para meters are d Hr tan and e as well as or tan such that y urpo and the complex dielectric constant e
383. not possible to add a scaling factor to the IN card In this case the TG card must be used if the global SF card scaling option is not sufficient It is possible to use multiple nested levels of include files i e one include file can include another one and so on It is also possible to specify together with the filename an absolute or relative path like in IN O subdir file inc In such a case if multiple levels of include files are used it is first tried to find the include file using the path relative to the location of the file where the IN card is used If the include file is not found there then PREFEKO also tries to find the include file using the path relative to the location of the main pre file which is processed EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 35 9 2 18 2 FEMAP neutral file This option is used to import models generated by the commercial CAD meshing program FEMAP The models must be exported from FEMAP in the neu FEMAP neutral file format IN Include an external file Import FEMAP neutral file y Y Include segments IV Include polygons Y Include quadrangles IV Include triangles F Include node points File name eee El Include all items C Include only items with single label layer Include items with range of labels layers FEMAP layers are converted to FEKO labels nclude structures with layer 25
384. nr O E o FEKOLANG Selects the language of operation This must be either d for German or e for English MKL_SERIAL Tf this is set to YES FEKO and all other codes using the Intel MKL libraries will run as a single threaded applica tion i e it will not utilise multiple CPUs irrespective of the value of OMP_NUM_THREADS see below OMP_NUM_THREADS Sequential FEKO versions for Windows or Linux PCs on Intel or compatible can use multiple CPUs on one board for the LU decomposition of the MoM matrix the parallel FEKO version will have all phases of the solu tion in parallel To use this the environment variable OMP_NUM_THREADS must be set to the number of CPUs to use See also MKL_SERIAL above December 2005 FEKO User s Manual 2 26 GENERAL COMMENTS 2 9 Checking the validity of the results If a calculation has been done with FEKO the results have to be checked There are a number of ways of doing this e acomparison with exact results if these are available e acomparison with results that have been published in the literature e acomparison with another program that is based on another method of calculation e a comparison with measured results e plausibility e g negative real input impedances do not exist If these possibilities are not available then the following should be tried e After a normal calculation with FEKO repeat it with a finer mesh see IP card section 9 2 19 The number of segments
385. ns Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read Rows per block This must be set to the number of rows that are to be read from each block i e the number of discrete points Vj pj when vary ing the angle The keyword OMNIDIRECTIVITY or RUNDSTRAHLUNG indicates that this aim function should be used For each block 1 Ng the roughness in dB is determined according to the relation max Ey Vj p fi 20 log E 1 min Ey Vj pj Here j scans through the values 1 Ny Using this error function the local aim function is related to the maximum roughness EM Software 4 Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 15 Radiation pattern This aim function can be used to optimise the radiation pattern according to an arbitrary shape specified by the user One can either optimise directly for a specific shape or one can specify a band and optimise e g for a main beam directivity greater than 10 dBi and a side lobe level of less than 20 dBi As for the isotropic radiator one can optimise for more than one frequency by using the frequency blocks from the output file from FEKO in the aim function Weighting factor Components Aim function op Aim 1 Select aim function Radiation pattern y Weighting factor fi Components Theta field component linear C Phi field component linear C Left hand ci
386. ns of any line are separated by one or more spaces or tab characters For example with a file containing Frequency in MHz Re load in Ohm Im load in Ohm 100 22 54 12 56 150 25 07 6 54 200 27 42 0 23 the frequency and loading can be imported directly from the file numfreq 3 Number of frequencies for i 1 to numfreq Define the frequency conversion from MHz to Hz freq 1 0e6 fileread datafile dat i 1 1 FR 1 0 freq EM Software amp Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREFEKO 7 5 xx Define the load Zr fileread datafile dat i 1 2 Zi fileread datafile dat i 1 3 LZ 0 Zr Zi Computations Inext End of frequency loop In addition to these functions PREFEKO allows the use of logical operations It supports the function NOT which returns TRUE if the argument is FALSE and FALSE when the argument is TRUE and the delimiters gt lt gt lt lt gt AND and OR When boolean operations are applied to variables a value of 0 is taken as FALSE and everything else is interpreted as TRUE Similarly in the result of a logical operation FALSE is mapped to 0 and TRUE to 1 PREFEKO also supports a logical function DEFINED variable which returns TRUE if a the variable variable has been defined and FALSE if not This is useful in pre files where during OPTFEKO TIMEFEKO or ADAPTFEKO runs certain variables are inserted into the header of the
387. nsuming FEKO solution It is also used to display the results of the FEKO simulation Multiple models with their geometry in FEK files and results in BOF files can be displayed in a single POSTFEKO session The displays are automatically updated each time a new PREFEKO FEKO run is executed All the display windows and their settings are saved to the POSTFEKO session PFS file Note that the results are not stored in the session file If a saved session is reopened POSTFEKO attempts to read all the FEK and BOF files that are required to re create the session If a session file is copied all the associated files must be copied in the same path relative to the session file If any of these files are not available when loading a session POSTFEKO will ask for replacement files A POSTFEKO session can therefore be used as a template to create the same set of displays for a number of different files POSTFEKO does not automatically save session files and a session remains unnamed until it is saved The POSTFEKO rendering requirements and configuration are the same as for CAD FEKO See section 4 1 2 6 1 1 Starting POSTFEKO POSTFEKO can be started by selecting Programs FEKO POSTFEKO from the Windows Start menu or by typing postfeko from a command prompt However in most cases POSTFEKO will be started from EDITFEKO or CADFEKO See the Getting started manual for an overview of the program flow When starting POSTFEKO from a command p
388. nt and magnetic dipole result in the same near and far fields if the dipole moment m is the same the radiated potentials are different The electric ring current model gives rise to a magnetic vector potential A while the magnetic dipole model results in an electric vector potential F as well as a magnetic scalar potential Y EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 21 10 2 10 A7 card This card is used to specify a voltage source on an edge between two triangles or at a connection edge between a single triangle and a PEC ground plane or UTD plate The AE card is substantially simpler to use and should be used for all new models The A7 card is supported only for compatibility with FEKO input files that were created before the AE card became available A7 Add a voltage at an edge New source C Add to sources Select segment Set source position Element label see manual poo Magnitude of source V ss Phase of source degrees A Coordinates of edge centre Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Select segment If this item is selected a triangle with label specified in the El ement label field is searched for The excitation is placed on the edge that lies opposite to the first corner of the triangle Once again the label must
389. ntered by the first one This card has no significance for surface elements even when these are assigned the same label December 2005 FEKO User s Manual 10 98 DESCRIPTION OF THE CONTROL CARDS 10 2 35 LS card This card can be used to assign discrete circuit elements in series to a segment LS Load segment with series circuit Label of segments to load J Resistor value Ohm J Inductor value H J Capacitor value F Figure 10 26 Sketch for the serial combination Parameters Label of segments All segments with this label are assigned the parallel circuit values specified below Resistor value Value of the resistor in 2 Inductor value Value of the inductor in H Capacitor value Value of the capacitor in F The impedance is given by Ls Rs j Ls A JW it If a capacitance of zero is selected it is interpreted as infinite capacitance i e in the case of the series combination it is zero The LS card may be combined with the LD LP LZ and the SK cards but only one LS card may be used per label If a second LS card is used it replaces the values entered by the first one This card has no significance for surface elements even when these are assigned the same label EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 99 10 2 36 LZ card This card can be used to assign a complex impedance to a segment LZ Load segment with comp
390. ntrol cards 10 5 a Weard osare ana a ER a A ES 10 5 1022 Axe Uards 2 440558 eee eee awe Dee ee ee 10 6 IEA ea oS he a oe kk be ee oo SG BRS ee ed 10 9 1024 A III 10 12 1027 A d ces sw RR ts a a ek a eae 10 13 WO ASO AY ee ee ee ee a 10 14 EM Software amp Systems S A Pty Ltd December 2005 CONTENTS ix 102 7 Alscard 2 ee ee eA a ne e ee 10 16 1028 Abcd 2 eae ee eee eee eee ee ee ee ee 10 18 10 2 9 AGeatd 22 552 ea ee eee ea ee ee ee 10 19 10 2 10 AY catd 22a ee eee ee eee Rh ee et 10 21 WOU AC aed saaa eee ee eee ee Gee ee aS 10 23 MNAE oe ee hae ebb dd ab eee eas 10 26 IIS AlO ee a a a a ee a ee eS 10 29 WS A AP GHA ocio ee eee eee ddd dea eae 10 31 10 215 ARCO i he A A A ns 10 38 10210 OE o s yk eta ee ate ee BR rane da A 10 43 DSO AO at ae cas Pe Be Soy eye By A Me hd 10 49 10 210 AW ATE eg a a a eee 10 51 OS TR eae nee ek AA a eR Sh a GS Sw 10 54 EZ Tao aa ao a a ee Ne a eee ke ee ce 10 56 WELRL EUA oi ROSA EH ERE A a e SESS SS 10 58 Whee CM Ceres cia rara a E ia a YS 10 62 TAB CO CAR cd A a ee ee R a 10 63 10 224 DA card eee roas tew eoa ee eee 10 66 10225 DI tard oa o Eee Aa O o asadi a 10 69 10 2 20 EN gata o eor pia aa Oe a a a BD 10 70 MI EEN 10 71 IES BESA o co a a ee bea eee aa N 10 79 WOR 29 PROA sico iso 10 83 ERIN AN 10 86 DRS Miel oo a RR da e e 10 92 ERA A hI DS ei a SAA EROS 10 94 MERMA ea a he OO ea a ee 10 95 EAS IP Gath a RRS AAA ESR REE 10 97 MEASS Ua Gad ooo Lasa ee oe Pe e
391. nts where the distance between points may be large compared to the triangle size elsewhere in the model This is done by deleting vertices which is a two step process similar to the subtract operation First select all the vertices which must be moved and press lt Del gt In the second step a final vertex is selected when prompted All the originally selected vertices are then replaced with the final vertex CADFEKO automatically removes all elements that become collapsed degenerate during this operation 4 13 6 Remove duplicate and collapsed elements Duplicate elements within a mesh part can be deleted automatically Generally duplicate elements should only occur in imported meshes or where CADFEKO meshes were edited manually Select the required mesh parts and select Mesh Remove duplicate elements from the main menu If duplicate elements have the same label CADFEKO deletes all but one If the elements do not have the same label it may be important to delete a specific element This is determined with the Remove duplicate mesh elements dialog shown in figure 4 22 The items are ordered by pressing lt Ctrl gt and clicking and dragging the numbers in the left hand column For each set of duplicates an element whose label is highest on this list is retained and all others are deleted There could of course be more than two identical elements Selecting Mesh Remove collapsed elements from the main menu will delete all degen
392. nvalid geometries for example the distance between points cannot become negative If the checkbox Enforce min max boundaries is checked the keyword ENFORCE_MIN_MAX or ERZWINGE_MIN_MAX is added to the opt file The provided boundaries are then strictly enforced when OPTFEKO creates a pre file for FEKO to ensure its validity This means that FEKO will produce meaningful results for any parameter value OPTFEKO assumes that the obtained result is for the ORIGINAL parameter set before enforcing the boundaries This means that a penalty function should still be added in order to force the optimisation algorithms to move back into the valid parameter range 11 2 3 Definition of the penalty function Penalty functions are used to ensure that the optimal result is obtained for realistic values of the parameters If the optimisation function calculates the response for parameter values that are outside the realistic range then a penalty is added to the aim function which effectively forces the optimisation function to consider this combination of values as non optimal Penalty J Include penalty function P_u specifies the value of the penalty function when the variable is 10 below the required range and P_o specifies the value when the variable is 10 above the required range Include penalty function This check box must be checked if penalty functions should be used for the optimisation Penalty function parameters The left han
393. o account Write debug information to dbg If this item is checked a debug file extension dbg is generated This file contains large amounts of information and should only be used when debugging Export UTD ray data for later viewing When this item is checked the ray information is exported to the bof and to a special ray file so that the ray paths can be displayed in POSTFEKO The ray information can become very large and thus it should only be exported if specific ray paths are to be examined Select ray contributions Determines which ray contributions to take into account e GO direct and reflected rays shadowing Geometric optics GO i e direct and reflected rays and shadow regions are taken into account e Edge and wedge diffracted rays Diffraction on edges and wedges are taken into account The ray may include an ar bitrary number of reflections but only one diffraction The total number of interactions the number of reflections plus one for the diffraction must not be larger than spec ified in the Maz no of ray interactions field EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 99 e Corner diffraction terms Corner diffraction e Double diffractions and diffraction reflection Double dif fraction on edges and wedges and combinations of reflec tions are taken into account Single diffraction rays are not included in this item e Creeping w
394. o if a component or variable is changed in such a way that the object is re evaluated suspect faces see section 4 7 will not be removed and some deleted faces may reappear Note that edges are not redundant if the normals of the surfaces are in opposite directions For this reason the back sides of faces are coloured different that the front normal sides in the Default view and it is possible to reverse face normals see section 4 7 8 The normals of triangles are in the same direction as the surfaces they belong to CADFEKO also allows automatic removal of redundant faces and edges Select Geometry Simplify to open the Simplify geometry dialog This operation allows removing specific types of items The simplified geometry will be electromagnetically the same as the original but may not have the same meshing constraints If for example an imprinted point is removed there will no longer be a guaranteed mesh vertex at this location Faces cannot be deleted unless the regions they separate can be merged The same applies to edges on the boundaries of faces and geometry points at the ends of edges By default the simplify operation does not remove redundant regions faces or edges on which local mesh properties see section 4 12 1 are set To remove them the various Keep with local properties options must be unchecked For example consider the union of two spheres of a similar dielectric medium shown in a in figure 4 16 A local me
395. o a vis file for reuse ufg Figure created and saved with GraphFEKO x_t Parasolid model file The files efe hfe ffe and os are redundant All the information in these files is also available in the out file The format of these redundant files lends itself more readily to further processing December 2005 FEKO User s Manual 2 22 GENERAL COMMENTS 2 8 Environment variables This section lists the environment variables that may be used to control the execution of FEKO See also the discussion of the installation the script initfeko or the batch file initfeko bat in the Getting started manual This script and batch file is usually automatically created by the FEKO installation program and the environment variables are set correctly Therefore the user does not need to set environment variables manually The following environment variables may be set FEKO FEKO_CMDINFO FEKO_HOME FEKO LITE FEKO_MACHFILE FEKO_MACHINFO Must be set to the path where the FEKO executables are located which normally is FEKO_HOME bin If this environment variable is set to the value 1 FEKO writes additional data concerning the number and the value of the received command line parameters to the screen This can be useful to trace errors in the parallel version of FEKO used in connection with some implementations of mpirun mpiopt mpprun etc This variable is set to the FEKO installation path which conta
396. o account At the connection point 72 a continuous current model is used such that a point charge is not possible here E metallic gt J triangles NI f f SS Figure 10 16 Impressed line current with a linear current distribution and electrical contact to conducting triangles December 2005 EM Software amp Systems S A Pty Ltd DESCRIPTION OF THE CONTROL CARDS 10 51 10 2 18 AW card With this card a waveguide port excitation by an impressed mode on a rectangular circular or coaxial waveguide can be modelled AW Waveguide port New source C Add to sources Label of the porttriangles Aperture geometry C Rectangular Circular Coaxial sf s2j re sf sf tw impressed mode excitation TE mode C TM mode C TEM mode Mode index m A Mode index n 4 Magnitude of impressed mode Aim Fis Phase of impressed mode degrees O i y Max index m in modal expansion Max index n in modal expansion Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Label of the port triangles Label of the triangular patches in the mesh which represent the waveguide port Rectangular A rectangular waveguide cross section is used which is defined by three points S1 S2 and S3 as follows S1 is an arbitrary corner point and 2 and S3 are two
397. o here CADFEKO does this proper meshing automatically When meshing dielectric solids into tetrahedral elements for the FEM then the faces of adjacent tetrahedra must match otherwise there would be a gap Also when modelling for instance a patch antenna and using metallic triangles to model the patch and tetrahedral elements to represent the dielectric substrate then also the metallic triangular elements must match the triangular facets of the tetrahedral volume elements See the example in figure 2 7 where this is illustrated In order to ensure proper connectivity of elements the FEKO kernel has several checks built in and will give errors if e g overlapping triangular elements are found Also CAD FEKO allows the user to perform several checks see section 4 9 December 2005 FEKO User s Manual 2 8 GENERAL COMMENTS Figure 2 7 Incorrect left and correct right modelling of metallic surfaces at the boundary of a FEM region 2 3 Usage and concept of labels In FEKO labels are an important concept to set electromagnetic properties or to do selections using only part of the geometry For instance in figure 2 8 the label Feed can be used to define the feed segment voltage source or the label MainRef1 can be used to instruct FEKO to use physical optics for the main reflector Labels are set either directly in CADFEKO or when using geometry cards then in EDIT FEKO using the LA card see section 9 2 26 When importing cert
398. ode ID is then in columns 9 to 24 the x coordinate in columns 43 to 56 y in columns 57 to 72 and z in columns 9 to 24 of the next line EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 41 For example P pp Lue E 73 Pp GRID 1 50 000000000 18 480176926 dl 1 23 222875595 GRID 2 50 000000000 18 480176926 2 2 13 410394669 For the comma separated format the individual entries are separated by commas GRID 1 0 238 533 186 7983 0 000000 0 GRID 2 0 244 777 214 3057 172 9991 0 GRID 3 0 288 0060 115 1831 339 8281 0 GRID 4 0 356 2201 50 15516 0 000000 0 CTRIA3 1 1 1 2 3 0 0 CTRIA3 2 1 1 2 4 0 0 December 2005 FEKO User s Manual 9 42 DESCRIPTION OF THE GEOMETRY CARDS 9 2 18 5 Import AutoCAD DXF file This card allows importing dxf models The dxf file must comply with the release 12 DXF format specifications It should contain meshed or closed polylines surfaces see the discussion below and lines that will be segmented by PREFEKO as discussed below IN Include an external file Import AutoCAD DXF file y IV Include segments Y Include meshed polylines triangles and quadrangles F Include node points vertex IV Include closed polylines meshed into triangles File name jl Include all items Include only items with single label layer C Include items with range of labels layers Layers named x L
399. of optimisation finds the minimum of the aim function by stepping through the optimisation space in a direction determined by the last n 1 samples where n is the number of optimisation parameters Optimisation Optimisation type Simplex y C Standard Nelder Mead Standard simplex method Basis fio ooo Scale ps Convergence foes Convergence hoea mNelder Mead Reflection fio ooo Contraction ps Expansion Po Standard This option is selected to use the standard simplex method where termination of the optimisation is determined from the size of the base of the simplex The base of the simplex reduces in size when the simplex starts to rotate about one node The standard simplex method requires at least two optimisation variables if there is only one use the Nelder Mead variant Nelder Mead This option specifies that the Nelder Mead variation of the sim plex method should be used This method allows for the simplex to reflect contract and expand The scaling factor for each action can be specified separately Basis The initial size of the base of the simplex Scale This factor specifies the factor by which to scale the base if the simplex starts to rotate about a point Base size termination The solution will be considered to be converged when the size of the base of the simplex is smaller than this value EM Software 4 Systems S A Pty Ltd December 2005 THE OPTIMISER OPTF
400. of the Qwt project see http qwt sf net 15 5 HOOPS and Parasolid POSTFEKO and CADFEKO use the HOOPS 3D Application Framework from Tech Soft America for the 3D display and rendering CADFEKO also uses the Parasolid Kernel Modeller from UGS to represent the geometry 15 6 MeshSim CADFEKO uses MeshSim from Simmetrix Inc to mesh the geometry December 2005 FEKO User s Manual Index card 9 3 10 5 2D results 6 10 3D results 6 7 3D view 4 4 AO card 10 9 Al card 10 12 A2 card 10 13 A3 card 10 14 A4 card 10 16 A5 card 10 18 A6 card 10 19 AT card 10 21 AC card 10 23 ADAPTFEKO 13 1 adaptive frequency sampling 6 10 6 11 13 1 add series 6 12 advanced solution options 4 46 AE card 10 26 Al card 10 29 angles Kardan 9 92 anisotropic layers 10 111 ANSYS 9 50 AP card 10 31 aperture 10 31 AR card 10 38 array sizes 2 16 2 17 AS card 10 43 assemblies 4 34 AutoCAD file 9 42 AV card 10 49 AW card 10 51 axes in POSTFEKO 6 6 Bezi r 4 21 BL card 9 4 BO card 10 54 Boolean operations 4 26 border PO correction edge 9 53 PO correction wedge 9 58 BP card 9 6 BQ card 9 8 BT card 9 10 CableMod 10 23 10 62 CADFEKO 4 1 availability 4 1 overview 4 3 calculations on series 6 12 variables 4 15 capacitance loading 10 94 10 97 10 98 card editing 5 6 CB card 9 12 CDB file 9 50 CF card 10 56 CFIE 10 56 CFM files 4 5 4 46 CFX files 4 5 CG car
401. of the angle 0 p increment Increment Ag in degrees of the angle p Compute spherical mode coefficients Check this item if the spherical mode coefficients of the far field should be calculated with the FF card The Maximum mode index N should be specified if this option is chosen More information on this option is supplied below When calculating the monostatic radar cross section for a number of directions of inci dence the parameter Fields calculated only in the incident direction is necessary otherwise Fields calculated as specified below can be used When using the FF card with Number of 9 points Ng and Number of p points Ny both larger than 1 the Poynting vector is integrated over the two spherical segments 39 2 Ad lt 9 lt vo No 4 Ad and yp 1 Ay lt y lt got N AY e Uo lt V lt Do Ny 1 A and yo lt p lt yo Ny 1 Ap In the case of an antenna the power provided by the voltage sources must be equal to the radiated power over the whole sphere The total radiated power can be calculated using for instance the following commands Far field integration in angular increments of delta in degrees delta 5 nt 180 delta 1 np 360 delta 1 FF 3 nt np 0 0 0 delta delta The output in the out file then reads for example Integration of the normal component of the Poynting vector in the angular grid DTHETA 5 00 deg and DPHI 5 00 deg 2701 sample points
402. of this aim function as compared to additional aim functions Elec Mag Select this option if either the electric OR magnetic field should be optimised Linear Select this option if a linear combination of the electric and mag netic fields should be optimised Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 23 Number of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read Note that different values for this parameter can be set for the electric or magnetic fields Lines per block The number of samples in each block that should be read Note that different values for this parameter can be set for the electric or magnetic fields Components The field component to be optimised is selected from this list Note that the options are dependent on the coordinate system that the near fields are calculated in The options of the field component direction are given inside round brackets on each line The first option is for Cartesian coordinates the second for cylin drical and the third for spherical The magnitude of the field strength is evaluated in each case Ng gives the number of blocks containing electric or magnetic near field strength values to read and Ng gives the number of lines to read from
403. ol the Mes oa Ga eR a eS 2 19 28 Environment variables c se dosaen rra et 2 22 2 9 Checking the validity of the results 2 26 December 2005 FEKO User s Manual ii CONTENTS 3 The licence manager 3 1 3 1 Displaying licence information 004 3 1 a2 Managing Hostia licences lt ddd a ee 3 2 dal Preferred licenc ms a Ac 3 3 3 2 2 Managing the server o 0050050 3 4 3 3 Determine the machine code 3 4 4 Working in CADFEKO 4 1 Wl is AAA eo ee on ee ee ee Oe OS 4 1 4 1 1 Starting CADPERO 200000000000 ee aa 4 1 4 1 2 Display settings and graphics cards 4 1 42 DADPERO overview eaaa a S406 de boca dd es 4 3 4 2 1 Thestendard toolbar s sasaaa naana ee eS 4 4 4 2 2 ISR models oc iii areas a a a oes 4 5 Lo ESO a A BB A es 4 5 4 3 1 The workplane oscc co oooroos sc 4 6 4 3 2 Transforming the workplane o o 4 8 4 3 3 Snap mode os eaaa cda ee ee a eee ARE ee 4 8 4 3 4 The SD ven toolbar ss a Ee sena a Ge cee es 4 9 4 3 5 A A GROG SEE eR a GAS RRR ES 4 10 4 3 6 DOISBLIVE VIENE lt o sona aba ee ee ws A a a e E 4 10 Me REE hak ae be A SPE gh AYA By AL Peo 4 11 4 5 Variables and named points 2 02 4 13 4 5 1 Named points aa 2 000686804 444 aa ae eS 4 15 4 5 2 Caloulatyt oi a eee ee wee a RR EE 4 15 40 Cr ate Geometry cocoa a i ee ee ee g 4 16 4 6 1 Geometiy een o ER a ka eS 4 16 4 6
404. olation GLIMIT TS Termination ITOL fio 87 Fletcher 1 Polak 2 RE Ct Restart parameter 0 1 1213 jo JV Delta for all variables a Values senn o EKO can calculate either the one or two sided gradient The use of two sided gradients requires more FEKO runs per optimisation point but generally provides better starting points for subsequent runs December 2005 FEKO User s Manual 11 8 THE OPTIMISER OPTFEKO Termination FTOL This termination parameter sets the value by which two subse quent runs must differ in order for the optimisation to continue If the difference between the aim functions starts to become very small then a optimum has been reached Termination GTOL The maximum value of all the gradients at a point is calculated If this value is less than this parameter the optimisation is ter minated Search step length LAMBDA This parameter is the search step size for the line search It is advisable to keep this parameter small since large values can result in a FEKO run that is very far from the current point Interval GOLD This parameter is important in determining the minimum and should be left at its default value of 1 618034 Extrapolation GLIMIT This parameter is important in determining the minimum and should be left at its default value of 100 Termination ITOL ITOL is the criterion for the termination of the one dimensional line search during reduction of the interval This termin
405. ols the size of the rectangle and the grid drawn on screen The workplane does not have to be symmetrical it may for example extend from 1 to 3 in the U direction It need not include the origin i e it may also extend from 3 to 1 or from 1 to 4 For mouse interactions the workplane extends to infinity i e points can be selected outside the blue rectangle While Auto enlarge is checked the workplane will increase to include all geometry created while it is checked This does not however resize the workplane relative to the existing geometry That can be done by right clicking on the 3D view and selecting Workplane Fit to geometry Clicking the Zoom to extents button December 2005 FEKO User s Manual 4 8 WORKING IN CADFEKO on the 3D view toolbar also fits the workplane to the current geometry The Grid spacing controls the density of the grid lines If the workplane size is increased to the extent that the number of grid lines is more than 10 000 in either direction the grid display button is automatically toggled off The grid can still be displayed by activating this button again However if the number of lines exceeds 100 000 the grid is not displayed 4 3 2 Transforming the workplane The Edit workplane dialog defines the workplane in global coordinates For arbitrary workplanes it can be very difficult to move the workplane normal to itself or to rotate it around one of its own axes using this dialog The Transform
406. ometric symmetry An asymmet ric object may then be placed in front of the plate In this case symmetry should not be used in the ray tracing Decouple with moment method When this item is unchecked the coupling between the MoM region and the PO region is neglected The implication is that the currents in the PO region has no effect on the current distribution in the MoM region This option which should lead to some saving in computational time and storage space is especially useful when the PO region and the MoM is not directly adjacent Use multi level boxing to speed up ray tracing The ray tracing required for the physical op tics is accelerated by recursively subdividing the problem domain aso called multilevel tree It must balance memory requirement against speedup both increase as the number of levels increases The number of levels is determined by specifying the number of triangles at the lowest level The user can specify not to use this algorithm for the program to determine maximum triangles box or to specify this number manually When a number is specified manually it should be greater than 2 and at least a factor 10 less than the number of triangles in the problem In general these options should only be set by advanced users Save read PO shadowing information For the PO formulation the information which tri angles are illuminated and which are shadowed from the sources is required Normally FEKO computes this e
407. ometry 4 23 mouse interaction 4 5 point entry 4 17 multilayer substrates defining 10 86 multiple reflections 9 76 multiple selection 4 35 N axis 4 16 named points 4 15 in PRE file 4 47 names 4 34 4 47 NASTRAN file 9 39 near fields 6 8 calculating 10 71 calculation offset 10 100 NEC file 9 46 networks 10 118 Neutral files 9 35 new model 4 5 nodes defining 9 19 definition 2 2 variable names 7 10 9 19 non uniform mesh 9 6 9 8 normal vectors 4 6 4 27 4 29 9 16 reverse 4 29 4 44 notes 4 48 NU card 9 68 NURBS surfaces 9 68 OF card 10 100 offset for near field calculation 10 100 ohmic losses 10 111 online manual 4 49 open model 4 4 4 5 OPTFEKO 11 1 editing files 5 9 options EDITFEKO 5 5 rendering 4 6 orientation view 6 6 OS card 10 101 OUT file 6 17 out of core 2 16 output file 14 1 overlap 4 33 Overview 1 1 pan 2D graph 6 14 model view 6 4 pan model view 4 5 paraboloid 4 19 9 70 parallel execution 5 4 parallelogram 9 6 parameters of segmentation 9 52 parametric 4 13 1 6 Parasolid 4 21 parts 4 11 show hide 4 10 PATRAN file 9 49 PB card 9 70 PCBMod 10 23 10 62 PDF viewer 4 49 PFG files 6 15 PFS files 6 1 PH card 9 72 physical optics 9 76 planar substrate 10 86 plane wave incidence 10 9 plate with hole 9 72 PM card 9 74 PO border edge 9 53 wedge 9 58 PO card 9 76 PO visibility 9 101 point entry 4 6 4 17 snap
408. on orientation of the workplane right click on the 3D view and select Workplane Edit or press lt F9 gt while the view has focus There is also an Edit workplane button on the 3D view toolbar This opens the dialog in figure 4 3 k 3D view 1 workplane 21 x Origin Size xfo pH U from 1 tfh voo m Vi hom A i fi F4 bo fiak IV Auto enlarge mU vector Grid spacing x fro E IT y foo ol z oo er Y Jot Y vector Set to plane x oo ol Global XY y fio ol Global ZX z foo al Global YZ Figure 4 3 The workplane dialog The workplane is specified in terms of an Origin which defines the position and a U vector and a V vector which define the orientation of the workplane Only the directions of the vectors are relevant i e using the vector 2 0 0 is the same as using 1 0 0 When calculating the V axis the component of V vector parallel to U vector is removed to ensure that the two axes are orthogonal Thus V vector may not be parallel to U vector The Origin U vector and V vector fields may be specified using the mouse see sec tion 4 6 3 i e the workplane may be used to enter values which define the settings of the workplane itself Clicking on the view while any of these groups has focus will modify its values and move the cursor to the next group The Apply button updates the workplane without closing the dialog Thereafter mouse point entry uses the new workplane The Size field contr
409. on With selection by mesh label all elements with the same label are selected unselected together Operations are applied to the selected label For mesh elements the selection and operations apply to the individual elements For example if a mesh label is selected and renamed the name of this label is changed If however a number of mesh elements are selected and renamed a new label is created and all the selected elements will now have this label Selecting items in the tree activates the appropriate what to select button Pressing lt Ctrl gt lt A gt will select all items of the current selection type Before a selection mode is changed the existing selection is first cleared with one exception When mesh labels are selected and the selection mode is switched to mesh elements the selection is converted Hence all elements remain selected as if they were selected as mesh elements If the View mesh edges button is toggled on down the edges of the selected mesh elements are highlighted This allows finding narrow elements where the surface may not be visible on its own While rotating the model i e before releasing the mouse button the mesh surfaces are hidden Hence if the geometry is hidden see section 4 3 4 rotating the model allows viewing the edges of the selected elements even those normally hidden behind other elements The Undo and Redo buttons on the selection toolbar allow reverting back forwa
410. on method The optimisation para meters are linearly varied between their minimum and the maximum values This can be useful to investigate the variable space before beginning the optimisation Due to the required computational time this is not recommended for more than two variables The value of the aim function is calculated at the specified discrete points No penalty function may be specified in this case Optimisation Optimisation type Discrete points y Number of points enh oo To use this option the only parameters that are required are the number of points at which each optimisation parameter must be sampled This value is entered into the table on the panel The panel can also be used to specify that the default descriptive comments should be added to the opt file December 2005 FEKO User s Manual 11 6 THE OPTIMISER OPTFEKO The keyword GRID_SEARCH or RASTERSUCHE is added to the opt file when choosing this function The number of discrete points required for each of the optimisation parameters are specified in the line following the keyword If this function was applied to a problem with two optimisation parameters where 8 samples of the first parameter and 9 samples of the second parameter are requested FEKO will be executed 72 times This example is given to highlight the computational cost of using this function for a large number of optimisation parameters Simplex method The simplex method
411. one copy is allowed A second copy would be back on the original and can be done with the standard Copy option EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 25 X Rotate 121 x Drigin xpo foo z Axis direction xo pj y foo of Rotation angle Angle degrees po o Set to global axis Set to local axis a a Ea ei A ee Figure 4 8 The rotation dialog Translate 121 x From Xx oy lo of z To x foo es Y foo HN zbo Figure 4 9 The translation dialog Mirror Ags Origin x a vpo zo SY TU vector x io on y foo on z foo on Y vector x Joo o yho ol z 0 0 ol Set to plane Global XY Figure 4 10 The mirror dialog A scale 21x Origin r off v flo of wo Scale factor Factor fio Cancel Figure 4 11 The scale dialog i of copies paisa Figure 4 12 The multiple copies section of the transformation windows December 2005 FEKO User s Manual 4 26 WORKING IN CADFEKO 4 7 3 Boolean operations The Geometry main menu and the Geometry modification toolbar provide access to the Boolean operations Union Subtract and Intersect The parts must be selected before requesting a Boolean operation Union combines all selected parts For Intersect the r
412. onent The field is assumed to be constant in the y direction and to have a cosine distribution in the x direction i e the s axis With Number of points along z 5 and Number of points along z 3 in practice more points may be required the data file will be as follows 0 0 0 0 0 0 0 0 0 0 0 0 0 707 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 707 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 707 0 0 0 0 0 0 1 0 0 0 EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 37 0 0 0 0 0 707 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 707 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 707 0 0 0 0 0 0 0 0 0 0 The zero values will not result in any dipoles but they must be in the data file to allow correct indexing The pre file will contain the following section Only electric fields use electric symmetry in the z 0 plane SY 1 0 0 2 Define the corner points of the aperture wx 0 02286 wy 0 01016 DP P1 wx 2 wy 2 0 DP P2 wx 2 wy 2 0 DP P3 wx 2 wy 2 0 The geometry ends after the corner nodes have been defined EG 1 0 0 0 0 Specify the frequency FR 1 0 9 375e9 Specify the AP card as a new source The amplitude factor of 2 0 is due to the use of the equivalence principle AP 0 3 Pi P2 P3 1 5 3 2 0 0 0 Guide dat which will generate nine x directed magnetic dipoles of the correct magnitude in the fek file December 2005 FEKO User s Manual 10 38
413. onnected in the order that they are listed Concave corners are allowed Parameters A The first corner point of the polygon B The second corner point of the polygon etc A maximum of 26 corner points are allowed The points are connected in the order that they are entered in the PY card The corner points have to be defined prior to the PY card by a DP card Example of PY card usage This card can be used to generate the polygon in this case a triangle shown in figure 9 35 Note that this triangle is not meshed as the result would be if the BT or PM cards had been used A Figure 9 35 Example for the PY card from demo_PY1 pre EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 81 9 2 33 QT card This card is used to create a dielectric or magnetic cuboid meshed into smaller tetrahedral volume elements for solutions using the FEM The meshing parameters as set at the IP card are used and the medium as set at the ME card is assigned to all created tetrahedral elements QT Specify a cuboid for FEM Ey LU ss a Parameters S1 First corner of the cuboid S2 Opposite corner of the cuboid if aligned with the principle planes otherwise one of the corners adjacent to the first corner S3 Optional third corner of the cuboid adjacent to the first S4 Optional fourth corner of the cuboid adjacent to the first
414. ons Most of the options and the list of recently used files do not need any explanation The New sub menu item opens a sub menu where the user may choose pre for PREFEKO opt for OPTFEKO or tim for TIMEFEKO files EDITFEKO will enter the appro priate mode depending on the selected option The Save menu will ask for a filename if the file does not have one otherwise it will save without confirmation using the current filename Various hot keys are presented next to the respective menu items The file menu is also used to set user preferences see section 5 3 5 2 2 Edit menu This menu provides general editing commands Note that multiple level undo redo is allowed Each change to the editor is recorded in the undo list When the user clicks December 2005 FEKO User s Manual 5 4 THE EDITOR EDITFEKO Undo the entry is moved to the redo list and the change to the editor is undone When new text is added by typing or adding a card after a sequence of undo commands the redo chain is cleared and the new text is recorded at the end of the undo list at that time It is possible to search the editor for specific text case sensitive or not The search always starts from the current cursor position If it is desired to start the search from the top of the file the cursor must be moved there using lt Ctrl gt lt Home gt Note that there is also a fast card search By right clicking on any button on the button panel the next
415. ose the medium Select here whether the sphere is dielectric or magnetic or both this is always with respect to the environment e g if the relative permittivity r of the cuboid material differs from the environ ment then this is a dielectric sphere Old format with medium parameters For a detailed description of this parameter please see the QU card in section 9 2 34 Dielectric bodies treated with the volume equivalence principle using cuboids cannot be used simultaneously with dielectric bodies treated with the surface equivalence principle or the FEM or with special Green s functions December 2005 FEKO User s Manual 9 18 DESCRIPTION OF THE GEOMETRY CARDS Example of DK card usage The DK card can be used to create a mesh of the eighth of a sphere as shown in figure 9 12 Figure 9 12 Example for the DK card from demo_DK1 pre EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 19 9 2 10 DP card With this card points in space are defined These points are used to define the extent and orientation of other geometric entities and to locate excitations DP Define an input point Point name J X coordinate J Y coordinate J Z coordinate J Nurb control point weight To avoid ambiguity each point is assigned a name a 5 character string In the other cards e g BL card the points are referred to by their names Parameters Point name Name
416. ose to a point The point must have been defined before with a DP card and its name is passed in the input field for the reference point Note that this point can be located arbitrarily in space there is no need for this to be on the meshed structure Local mesh refinement for a line Here an adaptive mesh refinement is performed to obtain a finer mesh close to a line The line is defined by its start and end point These two points must have been created before with DP cards Multiple simultanesously active RM cards can be used to perform a mesh refinement with respect to an arbitrary polygonal shaped line composed by multiple straight line segments Local mesh refinement for a cable harness With this option one can perform a local mesh refinement close to a cable harness The cable harness geometry is specified by a CableMod rsd file The filename of this must be entered into the respective input field visible only when this option has been selected Mesh polygonal plates As a special feature the RM card also allows to mesh unmeshed polygonal plates which are used in FEKO for the UTD during the import This can be very useful if e g a UTD model is im ported from FEMAP using then boundary surfaces and instead of the UTD a MoM or MLFMM or PO solution shall be conducted where a mesh is required Reference point When using local mesh refinement with respect to a point then here the name of this point is entered the point must h
417. pace and FEKO uses the free space Green s function by default For a few specific interaction environments some of the complexities of the environments can be taken into account using special Green s functions The Green s functions that FEKO supports are e Homogeneous medium The dielectric properties for the entire problem space can be set This is useful for modelling in a homogeneous medium that differs from free space e Layered dielectric sphere A layered dielectric sphere located at the origin is taken into account with the Green s function e Planar multilayer substrate A multilayer dielectric substrate in the xry plane is taken into account The substrate can have metallic ground planes above and below it Using Green s functions to model the presence of these dielectric regions means that their influence is taken into account implicitly using less computational resources than mod elling them using either the volume or surface equivalence principles The disadvantage is that they are only available for these specific environments The dialogs for each of the three cases above are discussed separately below EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 87 10 2 30 1 Homogeneous medium GF Specify Green s functions Homogeneous medium Layered dielectric sphere C Planar multilayer substrate When this Green s function is
418. permeability ur of the coating layer Relative permittivity Relative permittivity of the coating layer am Of the outer layer Conductivity Conductivity o in Magnetic loss factor Magnetic loss tangent tan 6 of the coating layer the complex permeability is then given by u Hour 1 j tan d Dielectric loss factor Dielectric loss tangent tan of the coating layer an alternative way to specify the conductivity a the two loss terms are related by tan and have different frequency behaviour Were Wire radius Wire radius o of the metallic wire without layers in m it is scaled by the SF card This overrides the values specified with the IP card This field is only applicable to wire coatings When using the Popovic formulation for wire coatings the following restrictions apply e The loss tangent tan 6 of the layer which is calculated from the conductivity o and the relation tan 2 has to be identical to the loss tangent of the surrounding medium specified with the EG card usually free space e Due to the change in the radius of the metallic core no SK card should be active for the same label otherwise the skin effect and or the ohmic losses refers to the wire with changed radius EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 65 e For pure dielectric layers i e the relative permeability ur of the layer equals that o
419. pplicable to it This includes the global mesh size In an extreme example if an edge borders a surface which is the boundary of a region and all three items have a local mesh size the final mesh size on the edge is the minimum of all three these sizes and the global mesh size For faces and regions the properties dialogs also allow setting material properties see section 4 8 EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 39 X Edge properties 21x m Mesh size IV Local mesh size Mesh size fo 2 m Specified mesh vertices Point 2 ez Add Remove Wire segment radius JV Local wire radius Radius foo Apply Cancel Figure 4 21 The meshing properties for edges Initially the dialog shows the current state of the property for the selected item s If some selected regions have a local mesh size and others not or if the specified size is different the Local mesh size item is in a ternary i e not defined state If this is the case the parameters are not updated when clicking OK or Apply This box can still be checked or unchecked to set the properties on all selected items The Edge properties dialog also allows specifying fixed mesh vertices These are expressed as a percentage of the length along the edge These points can be specified with the mouse see section 4 6 3 in which case CADFEKO calculates the percentage for the point on the edge which is n
420. pposite corner and clicking again The proposed rectangle is drawn while the mouse is moved While the rectangle is drawn it is not possible to rotate pan zoom the model All items fully or partially inside this rectangle are selected Finally if Polygon select is toggled on a polygon is specified by clicking at successive corners The polygon is closed by clicking on the first corner again As an aid the circle at this corner goes blue when the mouse is moved to within a certain tolerance of the corner Note that the presence of cutplanes see section 4 3 5 has a significant impact on Rec tangle and Polygon select In the absence of cutplanes only the visible items either fully or partially inside the rectangle polygon are selected Note however that if the Face displacement on the Rendering options dialog see section 4 3 is too low faces immedi ately behind sharp corners may be visible When cutplanes are present all items are selected visible objects as well those that are completely hidden behind other items The selection techniques may be mixed For example select all the items inside a polygon then click the Single select button and add to the selection by pressing lt Ctrl gt or lt Shift gt and clicking on additional items December 2005 FEKO User s Manual 4 36 WORKING IN CADFEKO The seven what to select buttons set part face edge mesh part mesh label mesh element or mesh vertex selecti
421. principle direction see Angle of principal direction Number of layers The number of layers If this field is empty or 0 it defaults to 1 Thickness of this layer The thickness d of this layer in m if an SF card is present this is always scaled EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 115 SK Add a skin effect finite conductivity Affect all structures with label J Assume ideal conductivity High frequency approximation skin effect Static approximation skin effect Exact expression forthe skin effect Triangles as thin isotropic dielectric sheet Triangles as thin anisotropic dielectric sheet User defined surface impedance Relative permeability ral Magnetic loss factor tan 84 Reference direction E Number of layers 1 2 Layer 1 Thickness ofthis layer Angle of principal direction zm Rel permittivity Principal direc Orthogonal Conductivity Principal direc k Orthogonal oOo y Diel loss factor Principal direc Orthogonal Pp o i al K he principle directions are determined by first projecting the reference direction into the plane ofthe triangle along the normal direction This ector is then rotated around the normal vector in a mathematically positive sense with the specified angle for each layer E fi Principle directi on Angle of principle direction The angle a in degrees from which the princip
422. put fields subject to the maximum allowed length 10 characters for real values 5 characters for integer values For larger expressions additional variables have to be defined A variable is defined in the following way 2pi 2 pi vara 1 sqrt 2 varb vara 2 3e 2 sin pi 6 sin rad 40 vara 2 sum varat varb Note that the sign has to appear in the first column Variables may also be defined from the command line as described in the previous section In addition to plain variables also arrays with integer indices are supported like a 5 or more complex am_0 3 i ceil r 2 The expression between the square brackets must evaluate to an integer number which can also be negative The implementation of using arrays is such that they do not need to be allocated however they need to be initialised So for instance after having used the instructions for i 10 to 20 array_al i 3 i 10 array_bl i 0 Inext one will be able to use tarray_a 10 or array_a 17 or also array_b 12 in other expressions But trying to use for instance ttarray_a 5 or array_b 0 will result in an error message that an undefined variable is used On the right hand side of any expression variables that have already been defined can be used in conjunction with any of the following functions O brackets addition subtraction EM Software amp Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREF
423. put ports The positive port voltage is in the direction of the segment that it is connected to from the start to the end point of the seg ment Thus the input and output ports of the transmission line have unique orientations If this item is checked the transmission line connecting the ports is crossed Input port If Select label is selected in the upper group the input port the segment which represents the start of the transmission line is defined by specifying the label of the segment in the Segment label field in the lower group If more than one segment with the same label exists then the last segment with this label is used EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 119 If Specify position is selected in the upper group the input port is defined by specifying the Cartesian coordinates of the centre of the segment Output port Same as for Input port but applies to the end of the transmission line Calculate length from position If checked FEKO determines the length based on the geo metrical distance between the start and end points Transmission line length The length of the transmission line in metres This value is scaled with the scaling factor of the SF card Losses Losses of the transmission line in dB m Note that since the propagation constant is taken as the propagation constant of the medium in which the start and end segments are located the attenuat
424. r this option should be used with care it allows adding possibly corrupted data into a model which is assumed to be consistent The model should be saved preferably using different names before and after this operation EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 23 CADFEKO can also import other CAD formats using the Spatial InterOp translators Select File Import Geometry gt from the main menu Note that the translators are licensed separately If some menu items are disabled you do not have a licence to use these import modules If you need or want to evaluate these modules please contact your distributor If an import menu is selected CADFEKO asks for a filename and then opens the Import model dialog The Units group on this dialog displays the units of the imported model and allows setting the Destination units which should be set to the unit of the numbers as used in CADFEKO These units controls the scaling of the imported model Since the imported model is converted to Parasolid all the comments for Parasolid im ports also applies here Due to the differences in the internal representations converting CAD formats can have additional unexpected results In particular there is often situa tions adjoining surfaces no longer line up correctly This problem is compounded by the fact that CADFEKO does not yet have any CAD fixing tools Some imported models use a numerical representa
425. r 2005 FEKO User s Manual 10 56 DESCRIPTION OF THE CONTROL CARDS 10 2 20 CF card Set the type of integral equation for perfectly conducting metallic surfaces Parameters CF Type of integral equation Type of integral equation for metallic surfaces EFIE r IGRE C Applyto all labels Apply to single label only C Apply to label range From label J to label a Factor for CHIE Type of integral equation for metallic surfaces Here one can chose the EFIE electric field Apply to all labels integral equation and also the CFIE combined field integral equa tion See the comment below for more details The selected type of integral equation is applying globally to all metallic surfaces irrespective of their label Apply to single label only Here the selection of the type of integral equation applies to a Apply to label range Factor of CFIE single label only which is entererd into the field From label Here the selection of the type of integral equation applies to a range of labels which is entererd into the fields From label and to label In the CFIE formulation electric and magnetic terms are com bined with a factor Leaving this input field empty will select the default value of 0 2 which should normally be used The EFIE is the default in FEKO if no CF card is used or for labels where no setting is made at the CF card It is the most general formulation and can
426. r solutions which do not fit into the available RAM but do fit into the RAM plus virtual memory the user should tell FEKO what the actual physically installed memory is less a certain reserve for the operating system Up to FEKO Suite 4 2 the variables maxalloc or maxallocm were used for this purpose maxallocm This sets the maximum allocatable memory in MBytes For example the definition maxallocm 400 will allow a maximum of 400 MByte of memory to be allocated If this is not enough the matrix will be saved to the hard disk or the program will be halted For parallel versions of FEKO this memory limit applies to each process Note that if maxallocm is used it will have preference and maxalloc will be ignored if it is used in the same pre file maxalloc Similar to maxalloc but just specifies the memory in Bytes and not in MBytes These two variables maxalloc and maxallocm are still supported in FEKO Suite 4 2 and later for backwards compatibility reasons however their usage is strongly discour aged now Rather on Windows and Linux the FEKO memory management works fully automatic and the usage of virtual memory swap space is avoided On other UNIX versions such as HP UX or SUN Solaris during the installation an environment vari able FEKO_MAXALLOCM is defined and gets set in the initfeko script which specifies the physically installed RAM less an operating system reserve for a specific machine The EM Software 4 Sy
427. ral elements and not cuboidal ones But as opposed to the MoM the FEM matrices are sparse thus the memory requirement for a FEM volume mesh is much less as compared to a MoM volume mesh of the same model The FEM has also been hybridised with the MoM see example_42 or example_43 Examples Guide for combined MoM FEM examples For all these three techniques the medium must either be set in CADFEKO or through the use of ME cards see section 9 2 26 By using the ME card it can be specified whether the triangular elements shall represent metallic surfaces or dielectric surfaces For the surface equivalence principle it is also possible to define metallic triangles and segments within the dielectric regions The material properties are assigned through the use of the DI card in the control section of the pre file see section 10 2 25 Apart from these general formulations there are a number of special solution methods for dielectric bodies in FEKO e Thin dielectric sheets The volume equivalence principle is applied and the resulting equivalent currents approximated by a surface current see the SK card section 10 2 42 e Dielectric coatings Metallic wires or triangular surface patches can have some dielectric coating see the CO card section 10 2 23 e Dielectric half space e g ground surface In this case the reflection coefficient method is used see the BO card section 10 2 19 e Spheres consisting of one or more diele
428. rcular field component linear C Right hand circular field component linear C S polarised field component linear C Z polarised field component linear C Total gainidirectivity in dB C Horizontal component gain directivity in dB Vertical component gain directivity in dB C Lefthand circular gain directivity in dB C Right hand circular gain directivity in dB C S polarised gain directivity in dB C Zpolarised gain directivity in dB Treatment for multiple blocks Averaging over the blocks C Take maximum minimax principle F Min Maxvalues Number ofblocks Rows per block Cr O O Number of lines oOo O O N IV Include default comments This factor specifies the relative weight of this aim function as compared to additional aim functions The component of the radiation pattern that should be optimised December 2005 FEKO User s Manual 11 16 THE OPTIMISER OPTFEKO Treatment for multiple blocks The options in this box are used to specify the method to combine the local aim functions into global aim functions Min Maz Values This box should be checked if a range of values should be used as the optimisation target This is useful for specifying a minimum and maximum acceptable value Note that this includes also the case where e g the gain should just be smaller than a certain value i e maximum specified but no minimum just set the minimum gain to e g 999 99 dB N
429. rd to the previous next selection states respectively These states are stored in yet another undo redo list This list is cleared each time the model is changed for example when adding deleting modifying geometry or variables Note that just like the model manipulations selections are independent of 3D views i e they are shared between them 4 12 Creating meshes Select Mesh Create mesh or press lt Ctrl gt lt M gt to open the Create mesh dialog shown in figure 4 19 Indicate if all parts or only the selected parts should be meshed Unlike other dialogs the selection can be changed while the dialog is open This allows for example meshing different parts with different mesh sizes without closing the dialog The Edge length field specifies the default mesh size for the edges of triangles and tetrahe dra Note that some edges may be as much as 30 larger than this See section 4 13 1 All free edges edges not forming the boundary of a surface are assumed to be conducting wires and meshed into segments The Segment length field specifies the maximum length for these segments Normally the radii of these wires are specified on the geometry edges see section 4 12 1 below The Wire segment radius field specifies the radius which is applied to all free edges for which no local radius is specified If Enable volume meshing is checked all dielectric solids are meshed with tetrahedra See section 2 2 2 for a discussion of the
430. rdware rendering is only enabled when available on the user s system The sliders change the face displacement for geometry and meshes Setting the face displacement allows a trade off between edges appearing broken and supposedly hidden lines being visible The relative positions of the sliders also determine what is visible if both the geometry and mesh are displayed Different settings may be required for different view directions These options are stored in the CADFEKO configuration file A Rendering options 24 x Y Auto detect Face displacement Rendering mode The ideal face displacement depends on the graphics card This value should be increased if the edges appear broken and decreased if edges oie butter which are supposed to be hidden become visible G EE a Painters bal O e rra Reset OK Cancel Figure 4 2 Rendering options dialog Hardware z buffer 4 3 1 The workplane Each 3D view has an associated workplane which is used to specify 3D coordinates with the mouse The workplane is drawn as a blue rectangle on the boundary and the U V and N axes The workplane display can be switched off by clicking Show hide workplane boundary on the 3D view toolbar This applies to the current view only and will also hide EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 7 the grid There is also a separate button to hide only the grid To set the positi
431. re is no SK card for a given label All other parameters are ignored High frequency approximation skin effect High frequency approximation Static approrimation skin effect Static ohmic losses approximation Exact expression for the skin effect Use the exact expression of the skin effect for wires and or surfaces that is valid at arbitrary frequencies Thickness of elements The thickness d of the surface elements in m if an SF card is present this is always scaled Conductivity The conductivity in az Relative permeability The relative permeability ur of the material Magnetic loss factor Magnetic loss tangent tan the complex permeability is then given by u pour 1 j tan n December 2005 FEKO User s Manual 10 112 DESCRIPTION OF THE CONTROL CARDS Having both triangles and segments with the label Affect all structures with label should be avoided Separate labels and a distinct SK card for each label should be used In addition all wires with the label Affect all structures with label must have the same radius If this is not the case a unique label must be introduced for each radius It should be noted that the skin depth is given by skin 2_ where the radial wHo frequency w 2r f and the permeability y uy Lo e Assume ideal conductivity No further parameters e High frequency approximation skin effect The required parameters are ur tand and g and for surfaces also the thick
432. rection of an edge is arbitrary i e it does not matter which edge point is chosen as the end or start point of the edge Label of triangles Label of the PO triangles adjacent to the PO border i e the edge correction current from this edge is applied to all triangles with this label Note that the surface must be flat i e all triangles with the label specified here must lie in the same plane December 2005 FEKO User s Manual 9 54 DESCRIPTION OF THE GEOMETRY CARDS 9 2 21 KK card A mesh of surface triangles in the shape of a conical section can be created with this be distorted to have an elliptical cross section Cones or conical sections with included angles that vary from the top to the bottom or that do not start card The cone can also in a specified plane can Parameters S1 S2 93 S4 Start angle at the bottom End angle at the bottom Start angle at the top End angle at the top also be created KK Specify a circular cone section Sa gt 9 Se saj Start angle pat the bottom deg End angle pat the bottom deg Start angle pat the top deg End angle Pat the top deg Po Maximum edge length bottom i y Maximum edge length top Doo o Scale second half axis with Normal vector directed le Outward Inward The start point of the axis of the cone the centre of the base The end point of the axis the tip of the cone or the c
433. rent files for wires and surface elements the type of element selection is obligatory and determines the type of geometry file to be read The only other parameters supported here are the file name and scale factor The CONCEPT file does not contain labels If the concept model contains quadrangles they are divided into triangles Since wires don t have a radius in the model files the radius is specified with a preceding IP card Likewise the elements don t have labels and the label as specified at the last LA card before the IN card is used If there is no LA card the label defaults to zero As for the CAD models dielectric triangles or metallic triangles which form the surface of a dielectric are created by preceding the IN card with the appropriate ME card The CONCEPT files for wires are as follows number_of_wires x_start y_start z_start x_end y_end z_end number_of_wires times where the first integer specifies the number of wires followed by the coordinates of the start and end point of each wire The file is completely free format the values are just separated by white space The surface file is number_of_nodes number_of_patches xyz number_of_nodes times pl p2 p3 p4 number_of_patches times again using free format The values x y and z specify the node coordinates and p1 p2 p3 and p4 specify the corner nodes of the triangles in this case p4 is 0 and quadrangles 5A MoM code developed at the Universi
434. ressed voltage source is in the opposite direction It should be noted that the edge between the surfaces with labels Label on one side of edge and Label on second side of edge does not have to be straight One may for example excite two half cylinders against each other If an impedance must also be applied to the edge the AE card can be combined with the LE card For the case where the item between regions with two labels is selected more than two triangles may be connected to each edge section as shown in figure 10 5 However one of these triangles must have a unique label and all the other triangles connected to this edge must have the same label In figure 10 5 there is one triangle with label 2 at each edge between triangles and all the others have label 1 One may therefore specify an edge between labels 1 and 2 The edge in figure 10 6 cannot be used as a feed edge as there are more than one triangle of each of the two labels involved The edge shown in figure 10 7 cannot be used as a feed edge either as there are triangles with three different labels connected to each edge December 2005 FEKO User s Manual 10 28 DESCRIPTION OF THE CONTROL CARDS e Correct feed edge Figure 10 5 Example of a feed edge where more than two triangles are connected Wrong feed edge Figure 10 6 Disallowed feed edge there is no triangle with a unique label at the edge X Wrong feed edge Figure 10 7 Disallowed feed edge
435. rid MoM UTD techniques critical regions of the structure can be considered using the MoM and the remaining regions usually larger flat or curved metallic surfaces using the PO approximation or UTD In addition to these PO or UTD high frequency techniques since FEKO Suite 4 2 also a fast integral equation solver the Multilevel Fast Multipole Method MLFMM has been included As compared to the MoM this drastically reduces the memory requirement and CPU time and as compared to the PO UTD asymptotic techniques it is a rigorous technique not based on specific high frequency approximations which in the case of UTD are for instance only available for certain canonical objects limiting the range of applicability For the modelling of dielectric magnetic bodies the MoM as implemented in FEKO offers a number of different techniques such as the surface equivalence principle the The UTD implementation is currently limited to an arbitrary number of perfectly conducting flat polygonal surfaces or one perfectly conducting circular cylinder December 2005 FEKO User s Manual 1 2 INTRODUCTION volume equivalence principle special Green s functions for planar multilayer media or also approximations for coatings or thin dielectric sheets Since FEKO Suite 5 0 these methods are complemented by the Finite Element Method FEM which is available in a MoM FEM hybrid formulation and well suited to model highly heterogeneous objects Bu
436. ription of this parameter please see the QU card in section 9 2 34 Dielectric bodies treated with the volume equivalence principle using cuboids cannot be used simultaneously with dielectric bodies treated with the surface equivalence principle or the FEM or with special Green s functions EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 21 Example of DZ card usage Figure 9 13 Example for the DZ card from demo_DZ1 pre December 2005 FEKO User s Manual 9 22 DESCRIPTION OF THE GEOMETRY CARDS 9 2 12 EG card This card indicates the end of the geometrical input It is essential that this card is used Parameters EG End of the geometry input Write geometrical output to FF FEKO output file out FF Nastran file nas M STL file stl Send to standard output C Nothing Warnings errors progress messages FT Switch normal geometry checking off E Do notuse a edg file default C Store information in a binary edg file C Store information in an ASCII edg file Maximum identical distance Relative permittivity Relative permeability lp Conductivity Sim a Magnetic loss factor tan 6 Dielectric loss factor tan Mass density kgim 3 P om accuracy applies to FMM FEM only Double precision Single precision Write geometrical output to The geometry data of the segments and surface elements
437. rkplane for that view cannot be edited without closing the geometry dialog and going back to the open workplane dialog If the items a dialog applies to are no longer selected they are shown in green in the tree Generally items are selected before applying operations to them 4 2 1 The standard toolbar Model Domes oR New Open Save Notes New Undo Redo What s 3D view his This toolbar contains short cut options to the file menu items used to create open and save models The Notes editor item opens the notes view see section 4 17 The New 8D view item also available under the View menu and with the short cut key lt Ctrl gt lt 3 gt creates a new 3D display window All views apply to the same model The Undo and Redo items these are also available under the Edit menu and the short cut keys lt Ctrl gt lt Z gt and lt Ctrl gt lt Y gt apply to actions on the model i e all items that affect the model Typically these include creating and modifying geometry adding modifying deleting variables changing labels meshing etc If a variable is used in a workplane the model undo list is blocked after the creation of the variable To undo beyond that point the variable must first be removed from the workplane View operations such as rotation zooming etc have a separate undo redo list for each view There is also a separate list for undo redo of the selection shared by all views The undo lists are not sa
438. rmal execution C Save preconditioner to per file C Read preconditioner from per file C Read perfile ifitexists else create it Note The usage of the CG card is generally not recommended FEKO automatically chooses the appropriate solver and options These algorithms should work in all cases butfor specific configurations might not be optimal Advanced users may thus apply the CG for such special cases but should realise that convergence ofthe iterative techniques is not assured and using an inappropriate pre conditioner may result in a much higher memory requirement Parameters In the first drop down list the matrix solution method is chosen e Gauss Elimination LINPACK routines Use Gauss elimi nation from the LINPACK routines e Conjugate Gradient Method CGM e Biconjugate gradient method BCG EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 59 e Iterative solution with band matrix decomposition e Gauss elimination LAPACK routines Use Gauss elimina tion from the LAPACK routines e Block Gauss algorithm matrix saved to disk The block Gauss algorithm is used in case the matrix has to be saved on the hard disk i e a sequential out of core solution is per formed e CGM Parallel Iterative Method e BCG Parallel Iterative Method e CGS Parallel Iterative Method e Bi CGSTAB Parallel Iterative Method e RBi CGSTAB Parallel Iterative Met
439. rmat These formats can also be mixed in an input file e Column based format The basic form of the input cards is 1 6 10 15 20 25 30 40 50 60 70 80 90 100 110 I5 Ri Ra R3 Ra R5 Re I3 I4 INT STR INT STR INT STR INT STR INT STR REAL REAL REAL REAL REAL REAL REAL REAL The upper numbers indicate the columns The name field in columns 1 and 2 specifies the type of the card This is followed by five integer parameters J to 15 when read with PREFEKO these input fields may also contain strings such as node names containing five digits each and eight real parameters Ri to Rg containing ten digits each e Colon separated format This is some kind of free format input where the indi vidual integer and real parameters are separated by the colon character The main advantage is that then integer and real input fields are not restricted to 5 or 10 characters respectively For this card format still in columns 1 and 2 the card name must be used then followed immediately in column 3 by a colon The rest is free format so for instance this is a valid syntax DP S1 x y z BP S52 52 83 S4 December 2005 FEKO User s Manual 2 2 GENERAL COMMENTS All input and output parameters of FEKO are in SI units e g lengths are in metres potential in volts etc Note the angles are in degrees FEKO includes various scaling options see the SF TG an
440. rocessed any existing L4 load on that triangle is replaced For example if two L4 cards are used directly below each other the first specifying a 50 Q and the second a 20 Q load the segment will be loaded with 20 Q not 70 Q It must also be noted that if the L4 card is used in conjunction with an A4 card im pressed current source the load impedance of the L4 card is placed parallel to the input impedance of the A4 source it has no effect if it is in series with the current source i e the resulting input admittance is the sum of input admittance without the L4 load and the admittance added by the L4 card December 2005 FEKO User s Manual 10 94 DESCRIPTION OF THE CONTROL CARDS 10 2 32 LD card With this card it is possible to specify a distributed resistive capacitive or inductive loading or even a series combination of these values for a segment LD Distributed load Label of segments to load J Resistance Ohm m J Inductance H m J Capacitance Fim Parameters Label of segments All segments with this label are subjected to distributed loading Resistance The distributed resistance in 2 Inductance The distributed inductance in E Capacitance The distributed capacitance in E The combined impedance of the segment with length is then 1 Ls R iw L L ae za It should be noted that if the Capacitance F m is left empty it is treated as infinite such that it does not contr
441. rom the pop up menu 4 7 12 Exploding parts Selecting the Geometry Explode menu item will explode all selected geometry parts Separate new parts are created for each face and free edge of the original parts The new parts represent a snapshot of the geometry at the time it was exploded they are not parametric 4 8 Specifying dielectric media Before it is possible to use dielectrics in a CADFEKO model the dielectrics must be added to the Media list in the contents tree By default this list contains only Free space and Metal solid Dielectrics can be added by right or double clicking the Media entry or by selecting Geometry Create dielectric medium from the main menu The square icon next to the dielectric name in the Media list shows the colour used to display this dielectric when displaying the geometry in Colour by medium mode see section 4 3 4 This mode can be activated per view by clicking on the arrow next to the Show hide geometry icon on the 3D view toolbar The display colour for each medium can be set by right or double clicking the corresponding medium entry in the Media list December 2005 FEKO User s Manual 4 32 WORKING IN CADFEKO Dielectric properties are specified on regions The regions of each part are listed in the details tree under Regions These are the individual volumes of the part Sometimes imported models will use surface parts to define the boundaries of solid regions These
442. rompt a filename may be specified as a command line parameter If no extension is given POSTFEKO will search for PFS PRE FEK and BOF files in this order with the specified name When loading a PFS session POSTFEKO loads all the files which were active when that session was saved When called with a PRE file as argument POSTFEKO will attempt to load the associated FEK and BOF files If these files are not available at startup POSTFEKO will load them as they become available For FEK and BOF files it just loads the specified file This can for example be used to display results without loading the FEK file if it is extremely large If only a FEK file is loaded only the geometry can be displayed POSTFEKO will however automatically load the required BOF file if the user chooses to display 3D data This is associated with the same model and hence there are no ambiguities To display 2D data or plots the BOF file must be loaded explicitly December 2005 FEKO User s Manual 6 2 WORKING IN POSTFEKO If POSTFEKO is started without an argument it will load the last active session pro vided that session was not unnamed and hence not saved If started from EDITFEKO POSTFEKO will open a new session and load the FEK and BOF files if they are available or when they become available This makes it possible to view the geometry and plot results It is also possible to load additional BOF files and compare results 6 2 POSTFEKO overv
443. rotation an origin and a direction and a rotation angle The angle is taken in the mathematically positive sense around the specified axis and is specified in degrees In CADFEKO radian angles are only used in the arguments and results of the trigonometric functions and their inverses The Set to axis buttons allow quick selection of common axes Note that the local axis buttons are only available if all selected parts have the same local coordinate system Note that the normal directions of the resulting surfaces depend on the direction of the curves There are a number of restrictions on the relation between the part and the spin axis No free edges may be coincident with the axis nor are they allowed to intersect the axis at any point other than at the ends of the curve For full spins of parts with faces the axis may not intersect the face at only one point unless it is at an end point of an edge The axis may be coincident with any edge of the sheet provided that the entire edge lies on the axis In addition no edge may touch the axis tangentially as shown in figure 4 14 not even if the edge is broken at this point Again it is allowed if the entire edge lies on the axis 4 7 6 Loft surfaces The Loft operation forms a smooth surface by connecting two curve parts with straight lines This is sometimes called a ruled surface but it is not a faceted model unless one or both curves are polylines Curve bodies may consist of
444. round plane Real part of impedance Ohm J Imaginary part Ohm J Select load coordinates Radius of the connection pin Parameters Define a load at a coaxial attachment point Define a load with the following parameters Remove all L4 type loads previously defined This L4 card does not define a load but rather all previously defined L4 loads are deleted All the other input parameters of this card are ignored Select element The label of the triangle to load If there is more than one triangle with this label the one with the highest element number is loaded Set source position Alternatively the user may specify the Cartesian coordinates z y and z of the load point in the Select source coordinates group The triangle with the centre point closest to this point is loaded Transform impedance to ground plane The specified impedance refers to the metallic ground plane and a transformation must be done to get the correct load impedance at the triangle Real part of impedance Real part of the load impedance in 2 Imaginary part Imaginary part of the load impedance in Q Radius of the connection pin The radius of the load pin in m The source coordinates if entered and the radius of the connection pin if entered is optionally scaled by the SF card EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 93 The implementation is such that if an L4 card is p
445. rror is written to the message window and the variable is not modified The Modify variable dialog may be left open while editing the item which gave the error Thereafter focus reverts back to the Modify variable dialog Variables can be deleted via the pop up menu The delete operation will fail for all variables that are still used for example in defining other variables or geometry The variables EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 15 cO the free space wavelength eps0 the free space permittivity mu0 the free space permeability zf0 the intrinsic wave impedance of free space pi the constant 7 are defined as part of a new model There is nothing special about these variables they may be deleted and or modified just like any other variable 4 5 1 Named points Named points can be created by double clicking on the Named points entry in the tree by right clicking it and selecting Add named point or by selecting Geometry Add named point from the main menu They are effectively vector variables and are typically used to create geometry that should change when the point is modified see section 4 6 3 The Add named point dialog contains input fields for the three coordinates of the point in the global coordinate system The x y and z components of a point are accessed using a dot followed by the required component for example P x is the
446. rting on label And ending at label IV No averaging of currents at triangle corners Parameters No currents No current output but does start calculation All currents Output all currents on triangles metallic and dielectric Only the currents on triangles Only output the currents on surface triangles Only the segment currents Only output the currents on wires Currents on structures with single label Output all currents on segments and triangles with the label Extract currents on this label Currents on structures with label range Output all currents on segments and triangles in the label range specified by the fields Extract currents starting on label and And ending at label All segment currents to rsd CableMod file Export the currents on all segments to a rsd file in CableMod PCBMod format see the comment be low Segment currents label range to rsd file Export the currents on all segments with la bels in the range specified by the fields Extract currents starting on label and And ending at label to a rsd CableMod PCBMod file No averaging of currents at triangle corners For the output of currents in the vertices of the triangles neighbouring triangles with common vertices are identified The current densities are then averaged over the neigh bours This ensures that the graphical representation is a smooth colour representation without discontinuities With this switch December 2005 F
447. s For some of the libraries the usage condition is that the cor responding copyright notices must be reproduced in the accompanying documentation This shall be done here 15 1 Copyright to Voronoi The preprocessor PREFEKO uses part of the program voronoi to execute a Delaunay triangulation for some of the geometric cards The copyright declaration for voronoi is as follows The author of this software is Steven Fortune Copyright c 1994 by AT amp T Bell Laboratories Permission to use copy modify and distribute this software for any purpose without fee is hereby granted provided that this entire notice is included in all copies of any software which is or includes a copy or modification of this software and in all copies of the supporting documentation for such software THIS SOFTWARE IS BEING PROVIDED AS IS WITHOUT ANY EXPRESS OR IMPLIED WARRANTY IN PARTICULAR NEITHER THE AUTHORS NOR AT amp T MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE 15 2 Copyright to SuperLU The FEKO kernel is using for some parts the SuperLU library The copyright declaration for SuperLU is as follows Copyright c 2003 The Regents of the University of California through Lawrence Berkeley National Laboratory subject to receipt of any required approvals from U S Dept of Energy All rights reserved Redistribution and use in source and binary forms w
448. s on hosti and 2 on host2 If only one process will be started on any host then instead of the entry host3 1 in the machines file also the shorter form host3 can be used EM Software 4 Systems S A Pty Ltd December 2005 THE FEKO SOLUTION KERNEL 8 5 Such a machine file the file mpi share machines feko under the FEKO installation path FEKO_HOME is automatically created during the installation of the parallel version of FEKO By default FEKO uses this file If a different distribution of the processes is required one can edit this file manually This is however strongly discouraged The user should rather create a separate machines file with the syntax described above If this file is for example machname the environment variable FEKO_MACHFILE can be used to force RUNFEKO to use this file instead of the default The required commands for the sh shell are FEKO_MACHFILE machname export FEKO_MACHFILE runfeko example_08 np 6 Alternatively one may pass the name of the machines file as an argument to RUNFEKO on the command line like runfeko example_08 np 6 machines file mymachines Using RUNFEKO is independent of the respective platforms and MPI implementations see also the discussion of the environment variable FEKO_WHICH_MPI in section 2 8 For very special applications or experienced users it may be necessary to pass additional options to MPI In such a case the appropriate MPI manuals should be considered
449. s 2 12 b and c These two problems can be solved using respectively electric and magnetic symmetry about the plane z 0 Each of these problems require only half the number of unknowns required for case a Superposition of the problems b and c which must unfortunately be done manually as FEKO cannot do it automatically at the moment yields the original problem The solution of each of the sub problems requires only half of the storage space required for case a For very large problems the solution time is dominated by the time required December 2005 FEKO User s Manual 2 14 GENERAL COMMENTS a b Figure 2 12 Separating a problem with geometrical symmetry into two problems with electric and magnetic symmetry respectively to solve the system of linear equations In this case the two sub problems each requires only one eight of the time required for case a 2 5 Dielectric solids There are numerous ways to model dielectric objects in FEKO three of these apply to arbitrarily shaped bodies e Method of Moments MoM with the surface equivalence principle There inter faces between different homogeneous regions are subdivided into a surface mesh using triangular elements Basis functions are applied to these elements for the equivalent electric and equivalent magnetic surface currents Boundary conditions result through the use of equivalent sources FEKO uses the normal vector of the triangles to dis
450. s BGG a he a e i 10 98 December 2005 FEKO User s Manual CONTENTS 10 2 36 LZ card 2 ee ee ee a a 10 2 37 OR ceed bai aa aa a eee bee ee 10 239 OS tard ek we a Be ae ae eed 10239 PRO ccoo 10 240 PW cad bh ke OE inean 10 241 5A eard a ee A 10242 SK Gard oe kc Ree we hE ERK ES 10243 SP oad oe oh ed irid daaa a 10 244 TLeard 2 baad aaa ann eee baa an 11 The optimiser OPTFEKO 11 1 Preparing input for OPTFEKO 11 1 1 Moreonthe pre file 11 1 2 More on the opt input file 11 2 Using EDITFEKO to create a opt file 11 2 1 The optimising toolbar 11 2 2 Definition of optimisation parameters 11 2 3 Definition of the penalty function 11 2 4 Definition of the optimisation process 11 2 5 Defining the aim function 11 3 Romine OP TFERO osos 060 so a a 11 4 An example using OPTFEKO 12 The program TIMEFEKO 121 Descriptor os e i p s pos a a e ee ee wa 12 2 The pre input fle o 123 The tim input Meco ee ee y reye es 12 3 1 Defining the pulse form 12 3 2 Definition of the frequency block 12 3 3 Definitions of the normalisation EM Software amp Systems S A Pty Ltd December 2005 CONTENTS xi 12 3 4 Definition of the excitation output 12 7 12 3 5 Definition of atime point 4 444 8 bee eee 12 7 124 Running TIMEFERKRO 2 24444 be a ee a 12 8 AA TIMEFEKO Guth
451. s and or wires File name O E Include all items C Include only items with single label layer C Include items with range of labels layers Component names CMBLOCK convert to FEKO labels nclude structures with property Up to property Scale factor The selection of polygons and quadrangles are not supported but all other non selection options discussed in the general section of the IN card is supported It also supports an additional selection option Include cuboidal volume elements Check this item to include cuboidal elements to be used with the volume equivalence principle in FEKO The component name from the CMBLOCK is converted to the FEKO label Since the FEKO label must be an integer value only component names which are integer strings for example 15 or end with an underscore followed by an integer string for example FEED_7 will be converted to FEKO labels 15 and 7 in the examples above In all other cases for example for a component name PATCH the FEKO label will be set to zero Note unlike most of the other CAD import formats supported by the IN card the ANSYS CDB file makes provision for a wire radius of the segments of type pipe16 real constant from the associated RLBLOCK This is then used during the import and any setting at the IP card is ignored the IP card radius is still used for filaments of element type 200 For dielectric bodies one must use an ME card to specify
452. s does not edit cards generated by PREFEKO such as the DR card The user should rather use the input cards that are read and converted by PREFEKO Generally it should not be necessary to use cards that are not available in EDITFEKO EM Software amp Systems S A Pty Ltd December 2005 THE EDITOR EDITFEKO 5 9 5 4 2 Variable editor The button on the top right corner of the button panel launches the card editor to edit variables This is useful as it presents a list of functions and operations understood by FEKO and calculates the value of the variable as it would be evaluated by PREFEKO at this point The functions variables or operations may be selected from the three drop down lists and a special group for the FILEREAD function The selected item is automatically placed at the current cursor position Note that variables and functions are highlighted after insertion but operations are not If a function is selected while some part of the variable string is selected the selected text will be inserted as the argument of the new function Variables operators and the FILEREAD function replace the currently selected text 5 5 OPTFEKO mode Editing OPT files is similar to editing PRE files All the standard editing operations behave in the same way However pressing lt F1 gt anywhere in the editor brings up the OPTFEKO dialog which edits the entire file The OPT file is divided into 4 sections the parameter section
453. s for the metallic triangles described above If there are any connections between triangles and segments then the following data is given GEOMETRIC DATA OF CONNECTIONS SEGMENTS TRIANGLES Data of triang data of segm info of symmetry no DRENUM DREPOI SEGNUM SEGPOI angle yz XZ xy status 1 11 1 360 0000 0 0 O unknown 15 1 45 0000 33 1 45 0000 55 1 45 0000 Each connection point is assigned a consecutive number which is given in the first column The number of the triangle at the connection point is given in the column DRENUM with the connecting vertex 1 to 3 in the column DREPOT Likewise the connecting segment s number is given in the column SEGNUM and the connecting end in the SEGPOI column If the begin point of the segment is connected SEGPOI 1 else the end point is connected and SEGPOI 2 The column angle gives the angle that is formed by the triangle at the connection point in radians The meaning of the symmetry information in the last four columns is the same as that of the metallic triangles given above EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 5 If dielectric volume elements are used then the following data block is given DATA OF THE DIELECTRIC CUBOIDS No x1 inm yi in m ziinm label x2 in m y2 in m z2 inm medium x3 inm y3 in m z3 inam x4 inm y4 inm z4 inm 1 0 0000E 00 0 0000E 00 0 0000E 00 O 3 3333E 01 0 0000E 00 0 0000E 00 Cube 0 0000E 00 3 3
454. s has no effect on the calculation of source currents or far fields Tf normalisation has been set NORM then the time points must also be given in normalised form Example Specifying the time points time has been normalised POINTS_IN_TIME 5 0 10 0 15 0 20 0 December 2005 FEKO User s Manual 12 8 THE PROGRAM TIMEFEKO 12 4 Running TIMEFEKO Firstly the input files pre and tim have to be created During execution new input files pre are continuously generated by adding the string _tim_ and a sequentially incremented number to the file name If for example the input files cube pre and cube tim have been created TIMEFEKO is executed with the command timefeko cube On the command line the following parameters can be added a Here an FFT is only performed on the already available data f The pre and out files are deleted after each iteration This saves disk space runfeko options After this option one can specify additional options which will be used in the launcher RUNFEKO for the FEKO kernel For instance in order to use the parallel FEKO solver during the time domain analysis one can use the command timefeko file runfeko options np 2 or also timefeko file runfeko options np 2 machines file m For a remote execution of the FEKO runs during the analysis on another host the suitable command would be timefeko file remote host hostname See section 8 2 for a list of all such RUNFEKO options
455. s parents of the Boolean operation the inner sphere can be copied to create a new root level part which fits inside the shell Copied items are created in the EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 31 root level even if the original items form part of an assembly It is also possible to make multiple transformed copies of parts See section 4 7 1 above The new part is completely independent of the existing one and neither will change if the other is modified If it is desired that they change together the original object should be created using variables as these are maintained during the copy It is also possible to select faces or edges of parts and select Copy In this case new parts are made for each selected item This allows for example an edge to be copied from a complex object and used to loft to another edge Note that these copies are snapshots of the model when the copy is made they are not linked to the parent object and are not parametric 4 7 11 Copy original If faces or edges are deleted from a part they are removed from the model These surfaces can be recreated by copying the parent objects of the affected part and redoing the operation which created the part This can be a very cumbersome operation for which CADFEKO provides a simple solution Select the required items and select Edit Copy special Copy original from the main menu or Copy special Copy original f
456. s the lists of variables named points and media and an overview of the geometry and meshes The entire history of the geometry creation can be seen in this tree Where objects are derived from existing ones for example the individual objects used in a Boolean operation or the original object in a split operation the original parent objects are removed from the top level of the model and listed under the new object in the tree The term part is used for highest level items These can be at the root level under Geometry or at the top level in an assembly and are the objects that are visible in the 3D view The tree can be expanded collapsed from the selection downwards by pressing or selecting Collapse Expand all from the pop up menu This applies to the focused item in the contents tree independent of which items are selected Unless detail for example faces are selected the focused item will be part of the selection Collapsing an entry will show all the direct parents only To hide the direct parents but keep the rest of the state use the key Likewise the key expands only the current level When specific items are hidden see section 4 3 6 they are displayed with gray icons in the tree The bottom or details tree shows the detailed information faces edges regions trans forms etc of a single part displayed in the contents tree with a bold italic font The lists of faces edges and regions only apply to
457. s two arguments fmod a b and returns the remainder of the division a b December 2005 FEKO User s Manual 7 4 THE PREPROCESSOR PREFEKO RANDOM This function returns a random value in the range 0 1 If the argument X of RANDOM is 1 then a random number is returned For any other argument X in the range 0 1 this value is used to set the seed and then a random number is created using this seed Using the same seed allows one to create a deterministic and reproducible random number series If RANDOM 1 is called before any seed is set in the pre file then the returned values are random and not reproducible The internal seed is used based on the time when PREFEKO is executed X_COORD This function returns the x coordinate of a point previously defined by a DP card The name of the point in quotation marks is passed as an argument to the function for example DP PNTO1 1 234 0 4567 tz x x_coord PNTO1 will set the parameter x equal to 1 234 Y_COORD Returns the y coordinate of a previously defined point similar to the function X_COORD discussed above ZCOORD Returns the z coordinate of a previously defined point similar to the function X COORD discussed above The FILEREAD function reads a numerical value from an arbitrary ASCII file The general syntax is fileread Filename Line Column and contains the filename the line number to read from and the column to read The data in the respective colum
458. same material parameters and loads same frequency same excitation but when one wants to compute the near or far fields with different options The storage of the LU decomposition is useful when only the right hand side of the system of linear equations changes e g the direction of incidence of a plane wave FEKO checks all this using checksums and reports a warning if for example currents were exported for one frequency and are later imported again for another frequency Note that the str file can be used for MoM MLFMM PO and FEM while the mat and lud files are only applicable when the standard MoM is used and then also only for sequential in core solutions Note that models built with PREFEKO on different computers may not be identical due to very small rounding differences of different CPUs It is therefore advisable to run PREFEKO only on one computer when using this card to ensure consistency in the fek files The fek files can then be copied to another computer if required For example a user may calculate and store the current distribution for a large model on a fast workstation and later load this to calculate different near fields on a small PC To ensure that current solution is valid on the PC the original fek file should be generated on the PC and copied to the workstation If the PS card is used to specify that data should be read from a file the PS card may occur only once in the input file It is advisab
459. selected the EM problem under investigation is modelled inside an infinite space of the homogeneous medium defined in this card This is the standard free space Green s function similar to when the GF card is not used The medium is normally free space but different parameters can be set with the EG card or in the GF card The parameters as set by the EG card is retained only when all the real parameters except the density p of the GF card is empty or zero If any of the medium parameters below is set all the EG card values are overridden Those parameters that are not specified will then default to the values given here Parameters Ene Relative permittivity of the homogeneous medium if this field is empty r 1 is used a Conductivity o in of the homogeneous medium tan Electric loss tangent tan of the homogeneous medium This is an alternative way to specify the conductivity the two loss terms are related by tan ET but have different frequency behaviour If both tan and o in are empty or zero tan is set to zero Hr Relative permeability ur of the homogeneous medium if this field is empty 4r 1 is used tan op Magnetic loss tangent tan d of the homogeneous medium the complex permeability is then given by u pour 1 jtand tan 6 is set to zero if this field is empty p The mass density in kg m This parameter is only required for SAR computations see section 10 2 4
460. sh size is December 2005 FEKO User s Manual 4 30 WORKING IN CADFEKO 4 Simplify geometry 2X m Points IV Remove redundant geometry points m Edges wires IV Remove edges on metal surfaces JV Remove edges on dielectric surfaces IV Remove wires inside metal regions JV Remove wires inside dielectric regions IV Keep edges wires with local properties Faces IV Remove faces between metal regions IV Remove faces between equal dielectric regions IV Remove faces between shell regions JV Keep faces with local properties Regions IV Keep regions with local properties Figure 4 15 The simplify dialog set on Region1 If the union is simplified with Keep regions with local properties checked the result is as shown in b Since the region contains local properties it is not removed Then the face between it and the centre region is also a removed If Keep regions with local properties is unchecked the result is as shown in c Figure 4 16 Illustrations of the simplify operation 4 7 10 Copy objects Geometry objects including parents of objects as shown in the tree can be copied to new root level parts by selecting the items and selecting Edit Copy from the main menu or using the short cut lt Ctrl gt lt K gt For example if a spherical shell is created by subtracting one sphere from another which will remove both original spheres from the model and list them a
461. single frequency will be analysed Discrete frequency points If this item is selected the following parameters are applicable e Number of frequency points For a discrete frequency sweep the number of frequency samples must be larger than 1 e Frequency scale In this group either Linear or Multiplica tive scaling is selected If Linear is selected then consec utive frequencies differ with a fixed value i e the new fre quency is the previous value plus the frequency increment If Multiplicative is selected then consecutive frequencies differ by a constant factor i e the new frequency is the previous value multiplied by the frequency factor e Specify by If Frequency increment factor is selected the user specifies the increment or factor mentioned in the pre vious item This the number of frequencies and the start frequency then determine the ending frequency If Ending frequency is selected the user specifies this and the incre ment factor is calculated December 2005 FEKO User s Manual 10 84 DESCRIPTION OF THE CONTROL CARDS Continuous data Select this item to use an adaptive frequency interpolation tech nique to obtain a continuous representation of the results in the given frequency band see Chapter 13 When using this feature the remaining parameters have the following meaning e Maz number of sample points Maximum number of discrete frequency points in this frequency band at which FEKO may be e
462. sis function cannot be determined from the symmetry but has to be determined form the solution of the matrix equation If 0 is present in the STATUS column then the coefficient of the current basis function is 0 due to electric or magnetic symmetry and does not have to be determined If there is any other number in the STATUS column then this number indicates another edge whose coefficient is equal to positive sign in the column STATUS or the negative of negative sign in the column STATUS of the coefficient of the current basis functions From symmetry the coefficient of the current triangle does not have to be determined The data of the dielectric triangles surface current method differ only slightly DATA OF THE DIELECTRIC TRIANGLES no label x in m y1 inm zi in m edges medium x2 in m y2 in m z2 inm medium x3 in m y3 inm z3 inm nx ny nz area in m m 1 O 1 0000E 01 2 0000E 01 8 5000E 01 1 2 3 1 1 0000E 01 4 0000E 01 8 5000E 01 1 0000E 01 2 0000E 01 8 5000E 01 0 0000E 00 0 0000E 00 1 0000E 00 2 0000E 02 2 O 1 0000E 01 4 0000E 01 8 5000E 01 f 4 5 1 1 0000E 01 2 0000E 01 8 5000E 01 1 0000E 01 4 0000E 01 8 5000E 01 0 0000E 00 0 0000E 00 1 0000E 00 2 0000E 02 In this case an additional line gives the components nx ny nz of the normal vector of each triangle EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 3 For the edges the extract is DATA OF THE DIELECT
463. smatch is not considered Total source power internal impedance All voltage sources are assumed to have an input impedance Z as specified by the parameters Source impedance real part and Source impedance imag part The currents are scaled such that the total power supplied by the voltage sources equals Po as discussed below The mismatch losses in the source impedance reduce the antenna gain Total source power transmission line feed All the antennas are assumed to be fed by transmission lines with a complex characteristic impedance Zz as specified by the parameters Charact impedance real part and Charact impedance imag part If there is a mismatch between Zz and the antenna input impedance Za some of the incident power will be reflected back to the source December 2005 FEKO User s Manual 10 106 DESCRIPTION OF THE CONTROL CARDS Decouple all sources when calculating power When this item is unchecked and multiple im pressed sources elementary dipoles A5 A6 impressed current el ements AI AV etc are present the mutual coupling of all these sources as well as the coupling of the sources with other struc tures such as ground BO card UTD surfaces or MoM elements are taken into account when determining the source power This is also the default if the PW card is not present When this item is checked however this mutual coupling is not considered This is acceptable for sources which are relatively far away or
464. sor is near the edge of the screen will also have a panning effect After a zoom operation the model will rotate around a point that is more or less in the middle of the screen at the same distance as the object zoomed on December 2005 FEKO User s Manual 4 6 WORKING IN CADFEKO Finally the display can be panned by clicking and dragging while pressing the lt Ctrl gt key or clicking and dragging with the middle mouse button The direction of the face normal is often important For example an edge between two surfaces with opposite normals is not redundant and cannot be deleted For this reason the front normal and back sides are coloured differently in the default colour view see section 4 3 4 and it is possible to reverse face normals see section 4 7 8 It is possible to hide see section 4 3 6 specific items If an item is hidden it is removed from all 3D views independent of the setting on the 3D view toolbar see section 4 3 4 In some cases the display may show items that should be hidden These rendering prob lems are very much hardware dependent and CADFEKO allows some configuration in this regard Select Options Rendering to open the dialog shown in figure 4 2 The Rendering mode group shows the algorithm used to remove hidden lines If Auto detect is unchecked it can be configured manually This may improve the display accuracy but it can have a significant impact on the rendering performance and memory usage Ha
465. st be visible and mesh vertex selection on and selecting Edit Properties from the main menu or Properties from the pop up menu This opens the Modify vertex dialog which contains the coor dinates of the vertex in global coordinates The input fields accept point entry see section 4 6 3 and expressions but these are converted to their values once the dialog is closed The point can be moved by a given amount rather than a specific position by adding the required offset to each field For example changing the X coordinate from 1 2 to 1 2 0 5 moves the point 0 5 units in the X direction 4 13 10 Creating mesh triangles Sometimes manual mesh fixing is required This may be because the mesh contains a number of holes or because some bad elements were selected and deleted Unlike deleting vertices see section 4 13 5 deleting elements leaves a hole in the mesh surface To this end mesh triangles can be manually constructed by selecting Mesh Create new triangle from the main menu This operation is only allowed if the selection contains a single mesh label in which case the new element is added to this label or a single mesh part in which case the new element is added to a new label created under this part The Create mesh triangle dialog allows specifying the three corners of the triangle Since these three fields are standard point entry see section 4 6 3 fields all the different snap options see section 4 3 3 are availabl
466. st common denominator of entries is used in the remaining lists For example if a FEKO run used a frequency sweep to calculate only input impedance and calculated the field patterns at one frequency selecting all frequencies will list the patterns in the third block even though they occur for only one frequency Missing entries are just ignored when plotting Again bi static RCS calculations behaves differently 6 5 2 Continuous adaptive frequency sampling As for the 2D case the Use continuous frequency checkbox is enabled if the BOF files contains adaptive continuous results See Chapter 13 In this case checking this box immediately sets the independent variable to frequency However it is possible to select a single frequency where the results are calculated and plot against another variable such as position If Automatically determine sampling depth on the Specify sampling dialog is unchecked a fixed number of samples can be specified Thus it is possible to interpolate the result at a number of discrete frequencies 6 5 3 New 2D graph toolbar The new 2D graph part of the main toolbar is used to create the different types of graphs These are only enabled if at least one BOF file is loaded Each item creates a specific type of graph and it is not possible to plot different quantities far field impedance etc on the same graph of lolol 1 2 3 WV S 6 7 1 Add a currents and charges graph plots segment curr
467. stems S A Pty Ltd December 2005 GENERAL COMMENTS 2 17 advantage then is that the FEKO pre files are machine independent i e if you have two different computers with different memory no variable maxallocm has to be changed in the pre file as such everything is either fully automatic Windows or Linux or defined on a per machine basis other UNIX versions 2 6 2 Other variables that are under user control In some cases memory blocks have to be allocated for data storage before FEKO knows exactly how big these memory blocks have to be In these cases it uses an estimate calculated by PREFEKO If the estimated size is too small FEKO will stop execution and give an error message The appropriate size now has to be declared in the pre file This is done by entering for example the line maxnv 100 as for normal variables see also section 7 3 anywhere in the pre file maxnp The maximum number of columns and rows which a block in the ma trix consists of in the Block Gauss algorithm which solves the matrix equation Dynamically 3 maxnp maxnp 16 Bytes are allocated for 3 blocks in the matrix maxnv The maximum number of connection points between wires and sur face triangles 2 6 3 Variables that are automatically set correctly Note that normally PREFEKO estimates the following variables correctly and they should only be declared in cases where there is an explicit error message stating that larger mem ory b
468. stems S A Pty Ltd December 2005 THE PROGRAM ADAPTFEKO 13 3 Just compute the impedance OS 0 End EN l I l Figure 13 1 Forked dipole used in the ADAPTFEKO example Note that we do not use adaptive meshing as the model is quite small This avoids the trouble associated with small discontinuities resulting from changes in the mesh Running ADAPTFEKO results in the file forked_dipole bof which can be processed in POSTFEKO similar to any other BOF file In addition the Use continuous frequency field on all the result panels is enabled This allows plotting the continuous result as a function of frequency or extracting the result at a specific frequency see section 6 5 2 For this example we create a new source data graph of Solution 1 Source 1 and plot the real and imaginary parts of the input impedance The resulting input impedance is given in figure 13 2 Figure 13 3 shows results over a small frequency band where a solution obtained with linear stepping is added to the same graph Note how close the results match even though ADAPTFEKO used only a single sample in this region This example was taken from the paper Efficient wide band evaluation of mobile commu nications antennas using Z or Y matrix interpolation with the method of moments by K L Virga and Y Rahmat Samii in the IEEE Transactions on Antennas and Propaga tion vol 47 pp 65 76 January 1999 In that paper they considered
469. structure The program PREFEKO can do all the meshing It automatically generates the geometric data in the form required by FEKO from the data given by the user The mesh density is controlled by a couple of parameters PREFEKO also imports mesh geometry for example constructed in CADFEKO integrating it with the final FEKO input file This section describe the principle workings of the program The user first defines the location of points in space with the DP card Structures are then defined in terms of these points For example two points may be joined to form a line BL card or four points for a parallelogram BP card 7 2 Running PREFEKO If for example a file example pre has been created using a text editor PREFEKO is started using the following command prefeko example After successful execution a file example fek is created This is the input file for FEKO The program PREFEKO allows a number of options which are mainly used for debug ging purposes Entering prefeko without arguments will give an overview of the syntax and supported options If for example the argument fek format x is specified PREFEKO creates a fek file using the x file format The option ignore errors makes errors non fatal i e PREFEKO continues with processing after encountering errors This can result in more errors as a consequence of the first one but it could also be useful to see all geometry modelling errors at once and not always
470. t all lines between else and endif are processed if the expression is FALSE Examples illustrating some of the points above are as follows lif ta gt 5 then llendif December 2005 FEKO User s Manual 7 10 THE PREPROCESSOR PREFEKO or 1 Ha b gt 21 and a lt 100 11if 3 at 5 gt x 2 and not 1 then llelse if sin x 10 gt 0 5 then else endif endif 7 6 Symbolic node names When defining or using node names simple variable names of the form A i are allowed The algorithm is that if a hash sign is found in a node point name this hash sign and everything that follows is interpreted as a variable string evaluated and rounded to the nearest integer Thus if we have k 15 and use or define a point P k then this is equivalent to using P15 as point name The length of the node name string before and after expansion is still limited to 5 characters For instance it would now be possible to define the points P1 to P20 inside a loop for k 1 to 20 DP P k Inext and use these either individually or inside another loop EM Software amp Systems S A Pty Ltd December 2005 THE PREPROCESSOR PREFEKO 7 11 7 7 PRINT and EXIT commands PREFEKO also supports the command exit to stop execution and the commands print and print_to_out to print strings enclosed in double quotes and floating point numbers to the screen and out file respectively Th
471. t also for homogeneous dielectric bodies the FEM might require less memory than the MoM Only time domain harmonic sources are supported in the current version and conse quently calculation is done in the frequency domain FEKO uses the e time convention Different sources are available including an incident plane wave various voltage gap for mulations on wire segments as well as triangle edges a magnetic ring current TEM frill with which a coaxial feed can be modelled and impressed currents and patterns Regarding the FEKO user interface this consists of three main components CADFEKO EDITFEKO and POSTFEKO CADFEKO is used to graphically create a geometry and do the required meshing for the FEKO solution kernel Alternatively the geometry can be defined in terms of high level commands in an input file pre which also sets the solution parameters The customised text editor EDITFEKO assists the user in creating and editing the input file The preprocessor mesher PREFEKO processes this file and prepares the input file fek for the program FEKO which is the actual field calculation code PREFEKO also supports the direct import of meshed geometry in FEMAP neutral NASTRAN PATRAN AutoCAD dxf STL or ANSYS cdb formats PREFEKO can also import and mesh polyline surfaces from unmeshed dxf files The ASCII out and binary bof output files of FEKO contain all the solution information The resulting fields and or curren
472. t defaults to y 1 If a point is rotated around more than one axis with a single card it is rotated first by an angle a around z axis then by a around the y axis and finally by az around the x axis A more detailed description of the transformation can be found in the description of the TG card section 9 2 38 In an exception to the rule that all geometry cards must appear before the EG card this card as well as the DP card can be used after the EG to define points for use in the AP card December 2005 FEKO User s Manual 9 98 DESCRIPTION OF THE GEOMETRY CARDS 9 2 41 UT card With this command the parameters for the Uniform geometric theory of diffraction UTD for the polygonal surfaces are defined UT Specify the UTD parameters Max no of ray interactions F Write debug information to dbg TF Export UTD ray data for later viewing Select ray contributions GO direct and reflected rays shadowing Y Edge and wedge diffracted rays Y Corner diffraction terms FF Double diffractions and diffraction reflection FF Creeping waves FF Cone tip diffraction J Uncoupled with moment method Parameters Maz no of ray interactions This parameter gives the maximal number of ray interactions i e reflection and diffraction combined If for example the parameter is set to 3 a ray can have 8 reflections or 2 reflections and a diffraction If set to 0 only direct rays are taken int
473. t from each FEKO label just the associated number is used see discussion in section 2 3 and exported then as the NASTRAN property The Maximum identical distance is used to set the tolerance in the mesh The mesh information is created by the program PREFEKO and stored in a x fek file in which all the triangles and segments are described by their corner points Due to rounding errors it is possible that for example end points of connecting segments do not coincide When searching for nodes an ohmic connection is made when the difference is smaller than the Maximum identical distance FEKO automatically checks for typical user errors that have been observed in the past Examples of errors are connecting a wire segment to the middle of another wire where the connection points do not coincide see figure 2 2 or connecting surfaces that have different segmentation along the common edge see figure 2 4 Such errors are detected if the parameter Switch normal geometry checking off is unchecked The error detection routine should always be used However if the same geometry is to be used a number of times the error detection can be disabled by checking this item If the surrounding medium is not vacuum one can set the material parameters with the EG card as shown above Alternatively the parameters of the surrounding medium can be set with the GF card which offers greater flexibility For example the GF card can be used to set the material para
474. t label of the edge Real part of impedance Real part of the complex load impedance Imaginary part of impedance Imaginary part of the complex load impedance Note that the edge between the triangles does not need to be straight One may for example specify a resistive connection between two half cylinders EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 97 10 2 34 LP card This card can be used to assign discrete circuit elements in parallel to a segment Figure 10 25 shows the parallel circuit that can be assigned to a segment LP Load segment with parallel circuit Label of segments to load J Resistor value Ohm J Inductor value H Capacitor value F Cp Figure 10 25 Sketch of the parallel circuit Parameters Label of segments All segments with this label are assigned the parallel circuit values specified below Resistor value Value of the resistor in 2 Inductor value Value of the inductor in H Capacitor value Value of the capacitor in F The impedance is then given by 1 Zp 7 JG Rp July IWCp If the resistance is set to zero then the resistance is interpreted as infinite i e in the parallel case it will not change the impedance The same applies to the inductance The LP card may be combined with the LD LS LZ and the SK cards but only one LP card may be used per label If a second LP card is used it replaces the values e
475. t the excitation of the structure 0 at t 0 is approximately 0 Since both the time and frequency domain data are continuous this is not strictly required but it simplifies working with the results EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO 12 3 ul 0 uo gt a T t T to tT 4 to gt Figure 12 1 Time function u1 t shifted by to The following pulses are available 1 Gaussian pulse GAUSS GAUSS see figure 12 2 u1 t uo e72 t to 12 1 ul t uo t Figure 12 2 Gaussian pulse Example Pulse form GAUSS kk to Exponent a 2 0E 08 3 0E 08 2 Triangular pulse DREIECK TRIANGLE see figure 12 3 t tol uo 1 for t to lt T ult 4 T lt tol lt 12 2 0 for otherwise Example Pulse form TRIANGLE to Impuls Duration T 2 0E 08 1 0E 08 December 2005 FEKO User s Manual 12 4 THE PROGRAM TIMEFEKO uo T T Figure 12 3 Triangular pulse 3 Double exponential pulse DEXP DEXP see figure 12 4 0 for lt to _ t to ui t lt U 1 e 71 for to lt t lt T to 12 3 t to uze 72 for t gt T to uo uo uy Ei Ua To 12 4 Le Ti e 72 E he T gt Figure 12 4 Double exponential pulse Example Pulse form DEXP ok t0 T taul tau2 0 0 10 0E 09 5 0E 9 10 0E 9 EM Software amp Systems S A Pty Ltd December 2005 THE PROGRA
476. t the segmentation parameters IP edgelen 12 3 The tim input file In the file tim the pulse form position and the point in time are assigned This file consists of a number of sections which are optional at present Set the pulse form with characteristic value and the time shift Set the size of the highest frequency and the sampling points Set the normalisation normalise time to the speed of light Set whether the output is written to the output file Set the time points In the tim file empty or comment lines starting with are allowed The parameters need not be entered in any particular column but they have to be in the correct order The keywords used in the tim file exist in German and English for example ANREGUNG and EXCITATION Both versions of each keyword will be given in the discussion below TIMEFEKO will recognise keywords in either language independent of the language selected by the environment variable FEKOLANG 12 3 1 Defining the pulse form The assignment of the pulse form is necessary Each pulse has a predefined name and has particular characteristic parameters The parameters must be assigned absolute values and not normalised values The amplitude factor uo is 1 It can be changed by using the Ax card in the file pre with the appropriate amplitude value Time shifting to indicates the time in seconds that the pulses are delayed see the shift in figure 12 1 The time shift should be such tha
477. t will default to the first entry if it cannot match the existing selection Thus the state of the selection should be carefully checked after updating to a results file with a changed structure 6 4 1 Result view toolbar The result buttons are used to view results in 3D Note that clicking these buttons shows the appropriate page on the control panel and adds a result component if there is no component of the selected type 1 The View currents and charges page works in conjunction with Geometry colour on the Main display options page 2 The View 3D far fields page controls the display of far fields The different polarisation options are discussed in section 6 7 The size of the pattern can be controlled with the Scale factor slider on the Options tab The Close check box on the Options tab completes the pattern if possible by linking the results with the largest values back to those with the lowest values It is also possible to move the origin of the pattern changing the position it is displayed relative to the geometry 3 The View near field ortho slices page displays near field slices If the Extrusion slider in the Ortho slice position group is moved to the right larger values are drawn further from the plane creating a kind of 3D amplitude plot Under Quantity with Instantaneous off Poynting is the averaged value gt s eee S Re E x H whereas the instantaneous value is gt a t Elt x R t whi
478. tal cb1 cos rad b1 cc1 cos rad c1 sail sin rad a1 sbi sin rad b1 sci sin rad c1 Some auxiliary terms resulting from equating the transformation matrices ttcc2 cb1 cc1 sqrt cb1 cc1 2 cal scl sal sb1 ccl1 2 cb2 cb1 cc1 cc2 ca2 cal cc2 cc1 sa2 cc2 sal ccl cal sb1 sc1 cb1 cc1 sb2 sal x scit cal sbi ccl sc2 cc2 cal scl sal sb1 cc1 cb1 cc1 Finally compute the angles which must be used in FEKO in the TG card for the rotation order first around z then around y and then around x a2 deg atan2 sa2 ca2 b2 deg atan2 sb2 cb2 c2 deg atan2 sc2 cc2 The file card based version of example_18 pre see the Examples Guide gives an example of an application of the TG card December 2005 FEKO User s Manual 9 94 DESCRIPTION OF THE GEOMETRY CARDS 9 2 39 TO card Using this card a surface mesh in the form of a toroidal segment can be generated TO Specify a torus section The angle Y degrees The angle degrees Max edge length direction Max edge length direction Scale second half axis with pos vector directed Outward C Inward Parameters S1 The centre of the toroid S2 A point that is perpendicular and is situated an arbitrary distance above the plane of the toroid 53 The start point of the axis of the toroid S4 A point on the surfa
479. taneously active RM cards Figure 9 38 Example of local mesh refinement with respect to a point from demo_RM3 pre Figure 9 39 Example of local mesh refinement with respect to lines demo_RM5 pre December 2005 FEKO User s Manual 9 88 DESCRIPTION OF THE GEOMETRY CARDS 9 2 36 SF card With this card the scaling of the geometric data is possible This is useful for specifying models in a convenient unit e g cm and specifying a scaling factor once since internally FEKO uses all dimension related values in metres SF Scale all dimensions IV Modify all dimension related values Multiply dimensions with J Note Normally the Modify all dimension related values box should be checked his box may be unchecked for compatibility with previous input files in case certain values such as source and field positions are not scaled In both cases all structural dimensions will be scaled including coatings and dielectric layers Parameters Modify all dimension related values If this item is checked all geometrical dimensions are scaled If unchecked some coordinate values are not scaled for example the positions of near field calculations see the list below This should only be unchecked for backwards compatibility with old input files Multiply dimensions with The scale factor For example if this is set to 0 001 all dimen sions are entered in mm Only one SF card is allowed in the input file T
480. ted scaled 3 times such that there will be a total of 4 structures If set to 0 the existing elements are translated rotated and the number of elements remains the same If this option is not checked then the TG card applies to all the previously defined geometry If this option is checked then a label selective processing is possible Copy structures starting from together with ending at label can be used to apply the TG card only to a selected part of the structure The TG card is applied only to those elements whose label lies within the range set here see also LA and CB cards and also general discussion of label ranges in section 2 3 If the second field is left empty only structures with the label set in the first field are considered Note that certain element types on the specified label s can be excluded from the selection lower in the card December 2005 FEKO User s Manual 9 92 DESCRIPTION OF THE GEOMETRY CARDS Label increment for the new structures Each newly generated structure will be assigned a label that is incremented by this value from that of the original structure An exception is the label 0 which is retained Include This group can be used to specify which element types provided they satisfy the label criterion are rotated translated Rotation around the x axis Angle of rotation a around the x axis in degrees Rotation around the y axis Angle of rotation a around the y axis in degrees
481. ted otherwise at the FE card the total value of the field i e the sum of the incident wave and the scattered field If the electric field inside dielectric cuboids is determined then the value for the SAR specific absorption rate and the cuboid number are also given EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE OUTPUT FILE OF FEKO 14 11 X m 0 050 0 050 0 050 0 050 VALUES OF THE ELECTRIC FIELD STRENGTH in V m inside the dielectric cuboids LOCATION EX Y m Z m magn 0 050 0 050 5 776E 00 0 050 0 150 2 192E 01 0 050 0 250 2 584E 01 0 050 0 350 2 625E 01 14 6 Far fields EY phase magn 59 89 1 259E 01 33 75 4 114E 00 31 18 3 420E 00 22 29 8 499E 00 EZ phase magn phase 177 82 1 415E 02 125 12 122 93 1 640E 02 130 45 19 21 1 679E 02 137 51 24 72 1 551E 02 144 87 SAR cuboid no in W kg 0 000E 00 0 000E 00 0 000E 00 0 000E 00 BwWN Fe If the far field is calculated the following block in this form is displayed VALUES OF THE SCATTERED ELECTRIC FIELD STRENGTH IN THE FAR FIELD in V Factor e j BETA R R not considered LOCATION THETA PHI 90 00 0 00 90 00 2 00 90 00 4 00 Gain is a factor of 1 00000E 00 ETHETA magn phase 1 235E 00 168 98 1 233E 00 168 90 1 227E 00 168 65 EPHI magn phase 0 000E 00 0 00 0 000E 00 0 00 0 000E 00 0 00 directivity in dB vert horiz total 7 1722 999 9999 7 1722 7 1583 999 9999 7 1583 7 1166 99
482. ted with the DA and FF cards e an external data file Read the radiation pattern from an ASCII file the format of this file is described below e after this line in the pre file The radiation pattern is specified in the pre file following the AR card the format is described below With this option one can make use of the FOR loops to generate patterns from known functions EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 39 Source amplitude scale factor The field strength values in each direction is determined from the data This parameter is used to scale the amplitude of the entire pattern by a constant value Phase of source This parameter specifies a constant additional phase for the entire pattern Source position In this group the x y and z coordinates of the source point i e the position where the antenna is placed is entered in m This value is affected by the scale factor of the SF card if used Rotation about the axes In this group the angle with which the imported pattern is rotated around the x y and z axis is entered We will refer to these fields as Qz Qy and az in the rest of this discussion Filename The name of the ffe or ASCII input file Start from point number This parameter is only relevant when the data is read from an external file and gives the line number of the first line to read from the input file If the data must be read from the beg
483. tegrate field over area given below The far field is calculated but it is not written to the output file in order to limit its size This option is meaningful when the individual values of the field strength such as directiv ity and gain are not required but the total radiated power has to be calculated from the integral of the Poynting vector see the discussion below or if one is just interested in the modal coeffi cients If a ffe file has been requested with the DA card the field values used in this integration will be written to the file Calculate only the scattered part of the field When this item is checked the field radiated by the impressed sources such as Hertzian dipoles is not in cluded This option is only meaningful if only the scattered field is required Normally one would not check this item so that the total field is calculated This includes all source contributions except plane wave excitations Directivity Gain Select which quantity is required December 2005 FEKO User s Manual 10 80 DESCRIPTION OF THE CONTROL CARDS Number of Y points The number of observation points in the Y direction An empty field will be set to 1 Number of p points The number of observation points in the y direction An empty field will be set to 1 Initial Y The angle Yo in degrees of the first observation point Initial p The angle yo in degrees of the first observation point Y increment Increment Av in degrees
484. tered Editing an existing line The editor dialogs can also be used to edit existing lines The line at the current cursor position may be edited either by pressing lt F1 gt or by right clicking at any position in the editor and selecting Edit line at cursor from the pop up menu Note that right clicking does not change the cursor position When the selection or highlighted part in the editor spans more than one line the line containing the cursor is edited For multi line cards the cursor can be anywhere in the card EDITFEKO processes each card as if it does not contain errors For some of the fields where the user may select a number of options the editor dialog s display will default to a common value if the input field is invalid Thus it is advisable to close the card editor with OK even when it was used just to check the validity of the line If the user types for example PS and then presses lt F1 gt EDITFEKO may treat it either as a new card with default options or as an existing card with all options blank zero Setting all options to zero does not always make sense and EDITFEKO thus treats this case as a new card and uses the normal defaults If the user wants to have a card with all options zero he should type the card name followed by a space before pressing lt F1 gt When editing existing lines the Add card button is not available as the card is edited and written back to the editor The card editor dialog
485. ters Use PO on all surfaces with label together with optionally up to label are used to specify the label or range of labels of all metallic dielectric triangles and polygons that are treated with the physical optics approximation If the second field is left blank only the label specified in the first field is considered See also LA and CB cards and also general discussion of label ranges in section 2 3 Do full ray tracing Normal complete ray tracing is carried out Assume all surfaces to be illuminated The ray tracing is switched off to save computational time The assumption is made that all triangles on which the PO approximation is made are illuminated by the source and the moment method area The side in relation to the normal vector is automatically determined EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 77 Full ray tracing illumination only from outside Full ray tracing is done but metallic tri angles can only be lit from the side to which the normal vector is pointing See note below Use symmetry in ray tracing If full ray tracing is done then symmetry can be used to re duce the computational time required to determine the shading For electric and magnetic symmetry this speedup is always used If geometrical symmetry is used then this item should be checked to utilise symmetry It is possible to e g define half a plate and create the other half through ge
486. th the CL card The first figure shows the result of a wire arc with a uniform radius and the second figure shows the result with an exaggerated taper specified gt Figure 9 10 Example of a CL card from demo_CL1 pre a A ae Figure 9 11 Example of a CL card with tapered wire radius from demo_CL2 pre December 2005 FEKO User s Manual 9 16 DESCRIPTION OF THE GEOMETRY CARDS 9 2 8 CN card This card is used to reverse the normal direction of previously created triangles or poly gons for example after importing CAD data CN Reverse triangle amd polygon normals Reverse normal of selected E Triangles Polygons Selection by e Label C Number Selection Parameters Reverse normal of In this group the user selects to reverse the normals of either Triangles or Polygons Selection by Here the user specifies whether the triangles polygons are iden tified by their Label or absolute element Number Selection The label element number of the triangles polygons that must have their normals reversed The normal direction is important in some cases such as when defining dielectric surfaces For triangles the normal vector is reversed by interchanging corners 1 and 3 For polygons the first point remains as is but the corner points are listed in the opposite direction The CN card changes the normal of the affected triangles but it does not change the settings of the ME
487. the s direction i e from point S1 to 2 For a circular coaxial waveguide m denotes the angular dependency Mode index n The index n of the TEm n or TMm n mode which is impressed at the port Note that for a rectangular waveguide the index n is related to the z direction i e from point S1 to 3 For a circular coaxial waveguide n denotes the radial dependency Magnitude of the mode in Absolute value of the complex amplitude of the impressed mode For a TE mode the unit is A m whereas for TM or TEM modes this is in V m Note that an amplitude of zero can also be specified In this case a waveguide port is acting purely as a passive port e g as waveguide termination and no wave is launched Phase of the mode The phase of the complex amplitude of the impressed mode in degrees Max index m in modal expansion At a waveguide port a specific mode is used as im pressed excitation However due to discontinuities also higher order modes can result and will be propagating back to the port applies to both active and passive ports Here the input value denotes the maximum mode index m which will be used to ex pand the backwards travelling waves It must be high enough to capture the resulting field distribution But note the higher this value is chosen the larger the impact on the run time and in particular also the mesh across the waveguide port must be chosen fine enough to represent the potential rapid field variation
488. the FF card in the last step The result is shown in figure 10 14 Figure 10 14 3D radiation pattern of the sector radiator EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 43 10 2 16 AS card This card specifies an excitation by means of impressed spherical modes which are either radiating i e propagating in positive r direction to infinity with r being the radius in a spherical coordinate system or incident onto a structure i e then propagating towards the origin r 0 AS Impressed spherical mode New source C Add to sources Propagation direction Inward C Outward Mode index numbering scheme Traditional index smn C Compressed indexj TE mode C TM mode Mode index m Mode index n Magnitude ofthe mode in y 1 pp Phase ofthe mode degrees iY a Source position x position y position Zposition This excitation option can thus be used for both the synthesis of an arbitrary electro magnetic field sum of the modes weighted with complex mode coefficients and also for the determination of the response i e induced voltage or power at a load of a receiving antenna due to the incident modes leading to the so called generalised scattering matrix Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to
489. the desired region All surfaces and scatterers inside the body must be removed and those outside retained For planar apertures for example the opening of a horn antenna one may use the mirror principle if the field at the edges can be neglected This results in a duplication of the magnetic current and cancellation of the electric current Thus it is sufficient to read only the electric fields and scale by the factor Amplitude scale factor 2 In this case any sources or structures in the region towards which the normal is pointing should also be subjected to the mirroring i e the structures should be electrically mirrored by using the SY card Further it should be remembered that the fields will only be correct in the direction that the normal vector points to The symmetric fields in the other half space will not be equal to the fields of the original problem Note that FEKO takes this into account and divides the total radiated power by two when calculating the power radiated by a planar aperture containing only electric or magnetic fields When the data is read from an ASCII format text file each line in the file represents one point and the values are space delimited For planar apertures it must have four parameters The absolute value and phase in degrees of the field component in the s direction followed by the absolute value and phase in the z direction see the example below The data must be such that the position increments
490. the first wave The direction of incidence is varied in the Y direction by the increment Increment in Y and in the direction by Increment in p In each direction these two angles are examined and a total number of incident waves equal to the product of these two angles are examined EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 11 If an AO card with either Number of 0 angles or Number of y angles larger than 1 is read all the following control cards up to but excluding the next Ax FR or EN card will be read into a buffer All these cards are then processed in a loop over all the different angles of incidence If e g the monostatic radar cross section is to be calculated for Y 90 and 0 lt p lt 180 the following command is used AO 0 1 181 1 0 0 0 90 0 0 0 0 0 0 0 0 1 FF 2 EN In this demonstration file the FF card is read into the buffer and processed 181 times Through the use of the parameter Fields calculated only in incident direction in the FF card the far field is calculated in the direction of the incident wave If more than one direction of incidence is to be examined the right hand side of the linear equation system is changed but the matrix remains unchanged Thus it makes sense by using the CG card to use Gauss elimination default if a CG card is not used which performs a LU decomposition of the matrix When the direction of incidence is varied then only
491. the interpolation tables for the Green s function of a planar substrate maxhacards The maximum number of HA cards used internally to set up micro strip ports that may be present in the fek file maxkanr The maximum number of internal edges also the number of basis functions per triangle It may be larger than 3 if more than two plates share an edge maxknonr The maximum number of nodes that may lie against a segment maxl4cards The maximum number of L4 type loads maxlab The maximum number of labels in a model maxlecards The maximum number of LE cards which specify a load on an edge between triangles maxleedges The maximum number of edges between two surface triangles that can be loaded with a single LE card maxlengz Dimension of the interpolation table used for the planar multilayer Green s functions This variable determines the maximum number of sample points in the z direction maxmedia The maximum number of different media used for the treatment of dielectric bodies in the surface equivalence principle The surround ing free space medium 0 is not counted i e with maxmedia 1 one dielectric body can be treated maxndr The maximum number of triangles maxnka The maximum number of edges between two triangles maxnkapo The maximum number of edges in the physical optics approximation maxnkno The maximum number of nodes between segments maxnlayer The maximum number of layers for the spe
492. the parameter table The user can then enter the penalty coefficients when the search moves below or above the specified range 5 5 3 Optimisation tab On this tab the optimisation process can be selected Note that the size of the Discrete points table is also dependent on the number of variables specified on the Parameters tab 5 5 4 Aim function tab This tab allows specifying the aim or goal of the optimisation The options for the various aim functions are explained in the OPTFEKO chapter see Chapter 11 Multiple aim functions may be defined by clicking the Add aim function button with the green plus icon Similarly the current aim function may be removed by clicking the Remove aim function button next to it The last aim function cannot be removed For Radiation pattern checking Min Max value adds a column to the table and allows specifying a target range rather than a single target value for each point For Near field values the number of lines in the values table is the product of the Number of blocks and Lines per block fields 5 6 Important keystrokes The arrow keys as well as lt Pg Up gt and lt Pg Dn gt behave in the normal fashion The following keys may be different to some other applications Cursor Movements Move a word left lt Ctrl gt lt Left Arrow gt Move a word right lt Ctrl gt lt Right Arrow gt Move to top of visible page lt Ctrl gt lt Page Up gt Move to bottom of visible page lt Ctrl gt lt Page
493. the surrounding medium such as coaxial cables filled with dielectric material one needs to reduce the length of the transmission line Losses in the transmission line network due to the shunt admittances or transmission line losses directly are taken into account and will for instance reduce antenna efficiency or gain The TL card is used in example_39 Examples Guide to create a log periodic antenna EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 1 11 The optimiser OPTFEKO Optimising is the process of changing parameters in a model to achieve a specific response These parameters are usually associated with geometric entities material properties or excitations loadings For example the maximum gain of property of a horn antenna can be optimised by varying the size of the horn opening As discussed in section 7 3 the program PREFEKO can handle symbolic variables All parameters that must be optimised must use symbolic variables OPTFEKO changes the value of these variables in a predictable way until the desired behaviour is obtained Apart from defining the optimisation parameters the aim or goal of the optimisation must be specified An aim function is used to determine how close the current solution comes to the desired goal The optimisation routine always finds the minimum so the aim function should be defined such that its minimum is the optimum solution OPTFEKO also makes provision
494. the type of optimisation required e Direct optimisation of a field component for the case where Min Maz values is unchecked The error function is given by Ng aS Pex Ey p 0 p5 is the electric field strength for the j far field line in the i block E ax represents the maximum field strength amplitude of the component which is selected in the i far field block i e E ax maxj Ep 05 p which is required to normalise the field strength to give the normalised radiation pattern EM Software amp Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 17 e Direct optimisation of a field component for the case where Min Max values is checked The error function is given by E lEs o 0 05 NEAGRA hom D D a P0 Pa e with the thresholding function 0 z lt 0 ra 9 gt 0 e Direct optimisation of a gain directivity for the case where Min Max values is unchecked The error function is given by 1 Ns i Jgh v t U is the gain or directivity in dB the component which is selected by M for the j far field line in the i block e Direct optimisation of a gain directivity for the case where Min Max values is checked The error function is given by ieee oa Ns T Gh v t 0 yi a Paes FE Pity Ghyv 95 y j l fi with the same thresholding function I x as defined above The key word RADIATION_PATTERN or RICHTDIAGRAMM indicates that this aim function is used
495. the value specified with the IP card is used This length is in m and is scaled by the SF card Set wire radius If checked the radius set at the previous IP card is overridden for the current arc This setting does not affect segments created after this card Both radius values are in m and are affected by the SF card scaling factor If only the start radius is specified the arc will have a constant wire radius Radius at start The radius of the wire at the start point Radius at end The radius of the wire at the start point Scale second half axis If this parameter is empty or is set to 1 a circular arc is created If set to 2 an elliptical arc is created Here 2 gives the ratio of the two half axes where a is the distance S1 83 It is recommended to generate elliptical arcs with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 15 Quite often modelling the geometry of an arc requires shorter segments than those used for straight wires Thus the maximum segment length specified with the IP card can be overridden along the arc by specifying a value in the field Maximum length of segments The radius of the arc is given by the distance between the points S1 and S3 Examples of CL card usage The meshes shown in figures 9 10 and 9 11 are created wi
496. this is set to 2 the wires only cross at every second segment Example of WG card usage The wire grid seen in figure 9 44 is generated using the WG card Figure 9 44 Examples of the WG card from demo_WG1 pre the one on the right has a value of 2 in Length of the grid gaps EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 105 9 2 45 ZY card With this card a surface mesh in the form of a cylindrical segment can be generated ZY Specify a cylinder section y sf 4 s2 de s3 J 1 A Normal vector directed 6 Outward Inward The angle degrees Maximum edge length on arc Scale second half axis with Parameters S1 The start point of the axis S2 The end point of the axis S3 A point on the corner of the cylindrical segment Normal vector directed The triangles can be created such that the normal vector is points Outward or Inward The angle p The angle in degrees which is subtended by the cylindrical arc Maximum edge length on arc Maximum edge length of the triangles along the curved side in m is scaled by the SF card If this parameter is left empty the value specified with the IP card is used Scale second half axis If this parameter is empty or is set to 1 a circular cylinder is created If set to 2 an elliptical cylinder is created Here 2 gives the ratio of the two half axes where a is the distance S1 S3 It is recommended
497. timisation process is stored in a log file with the extension log in the example above the filename will be dipole log It should be noted that when using the remote launching facility see section 8 2 3 the actual optimisation is done on the local machine only the FEKO kernel runs which are the time and memory consuming part are done on the remote machine December 2005 FEKO User s Manual 11 28 THE OPTIMISER OPTFEKO 11 4 An example using OPTFEKO In figure 11 1 a dipole antenna in front of a reflector is shown The gain is to be optimised The bent angle a of the dipole and the distance a between the dipole and the reflector are given as optimisation parameters The input files for this optimisation example can be found in your FEKO examples directory under utils optfeko dipole Figure 11 1 Bent dipole in front of a reflector As a first step a discrete point search is done by systematically varying the two optimi sation parameters to find the region of the minimum The gain the negative aim function can be displayed graphically In figure 11 2 one can see a clear maximum in the area a 10 and 0 8 The general position of the optimum is now known A new search can now begin with e g the simplex method by using the input found in dipole opt The extract from the log file reproduced below shows that the procedure converges for a 7 and 0 78 No alpha tta Aim fct Penaltyf
498. tinguish the respective dielectric media on the two sides see also the discussion at the ME card in section 9 2 26 It is advisable to check the normal vector orientation or directly the media us age colouring by media in POSTFEKO Example_04 Examples Guide shows a simple dielectric sphere A more complex geometry where a dielectric body is in contact with a conducting body is described in example_23 Further details can be found there e MoM with the volume equivalence principle Here the volume is subdivided into cuboidal elements In principle each element can be assigned a different material property Inside the element the polarisation current is unknown Normally since a EM Software amp Systems S A Pty Ltd December 2005 GENERAL COMMENTS 2 15 volume is meshed many more unknowns as compared to a surface mesh result so that this method requires a larger memory However this technique is very suitable for thin sheets and also very stable for low frequencies Another advantage is that it is based on a so called Fredholm integral equation of the second kind making the formulation very stable and thus when using MLFMM the number of iterations is typically small In example_09 Examples Guide a dielectric cube is analysed with the volume current method e As alternative to the MoM in FEKO also the Finite Element Method FEM is available Like in the previous method also 3D volumes are discretised here into tetrahed
499. tion 12 1 One should select approximately fmax 4 f3aB The number of frequency points N is then selected such that the total time T is long enough for the exciting pulse and all included currents radiated fields etc to have de cayed Once the total time has been determined the number of samples may be deter mined from the relation E 1 Ex Sraz Af 75 N 1 or EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO 12 7 Finally let P be the smallest power of 2 which is larger than or equal to N 1 For example for N 10 P 16 for N 33 P 32 and for N 50 P 64 Then the time stepping will be At sp o El With the relation lt N 1 lt P we get the bounds lt At lt 4 fmaz _ 2 aie 12 3 3 Definitions of the normalisation Using the keyword NORM NORM the time can be normalised to the speed of light in a vacuum co The normalised time then has a unit of lm light metre tnorm t Co Example Normalising time with respect to the speed of light NORM 12 3 4 Definition of the excitation output The keyword ANREGUNG EXCITATION indicates whether the time variation of the excit ing pulse is to appear in the output file Example Output the excitation pulse EXCITATION 12 3 5 Definition of a time point With the keyword ZEITPUNKTE POINTS_IN_TIME the near fields surface currents and line currents can be calculated at certain points in time Using time point
500. tion and scaling these can lead to problems The conversion is logged in the file FEKO_HOME logs CADimport log which is especially useful in cases where the conversion fails 4 7 Operations on geometry Any combination of objects can be selected and modified Most options are available from the main menu or the Modify geometry toolbar Modify operations include transforma tions Boolean operations Union Subtract and Intersect other advanced operations on parts such as projections Split Spin and Explode Rename to modify the label name of an object or one of its regions faces edges all objects in the model must have locally unique names Copy discussed below Delete also available via the short cut key lt Del gt Reverse face normals and Properties which opens an edit dialog similar to the create dialog Complex geometry is created from a sequence of operations starting with simple primi tives This sequence is shown in the tree It is possible to select and modify objects at any level in this tree or change variables upon which the geometry depends The tree is then re evaluated During this process CADFEKO may not be able to maintain the identities of some regions faces edges for example where multiple faces are derived from the same original face during Boolean operations These items are then marked suspect see section 4 4 as a warning that properties set on them may not have been maintained After ensuri
501. to 2 an elliptical disk is created Here 2 gives the ratio of the two half axes where a is the distance S1 S3 It is recommended to generate elliptical disks with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases December 2005 FEKO User s Manual 9 60 DESCRIPTION OF THE GEOMETRY CARDS The circle s plane is perpendicular to the line S1 82 This length is arbitrary The radius of the disc is given by the length between the points S3 and S1 The area that is to be subdivided the shaded region in the figure is generated by sweeping the edge S3 S1 around the axis S1 S2 through y degrees in the mathematically positive sense For y 360 a circle is obtained The fineness of the mesh is determined by the maximum edge length specified by the last IP card prior to the KR card Along the arcs accurate modelling of the geometry may require finer segmentation and the maximum edge length values specify the maximum edge length along the outer and inner if applicable arcs respectively If any of these values are not specified the length specified with the IP card will be used on the corresponding arc The normal vectors of the triangles on the disk all point in the direction from S1 to 2 Examples of KR card usage The following example meshes are all created using the KR card Shown is a circular plate a flat circular ring and a flat elliptical ring
502. to ADAPTFEKO d Debug mode with some extra output can be used to troubleshoot error The optional command line parameters for FEKO specified after feko options are check only If this option is used FEKO processes and checks the geome try but does not start a solution This is useful to test an input file on a local PC before submitting it to a parallel computer e ENV value This has the same effect as starting FEKO with the environ ment variable ENV set to value More than one e argu ment is allowed 8 2 2 Running the parallel version In order to use the parallel version of FEKO from the GUI one first has to configure the hostnames and number of processes which shall be used for each node This will be setup initially during the installation so one has to re configure only if there are changes To do this configuration open the Run menu then Solution options there on the top click on the FEKO tab and under Parallel execution click the Configure button Then a dialog as shown in figure 8 1 will open There the hostnames and number of processes to be started on each host must be entered Usually one would run one process per CPU which determines the number of processes for each host for example 2 processes for a dual board machine One may also use this for a crude load balancing running more processes on hosts with faster CPUs or more memory The Add machine button allows to add more nodes 4 Machines confi
503. to the view under the mouse cursor rather than the active view 4 3 6 Selective viewing In some cases where geometry or mesh parts are obscured by other items it can be difficult to set up cutplanes to view these items It is therefore possible to selectively hide geometry and mesh parts Hidden items are removed from all 3D views but are still part of the model and are still meshed and exported to the CFM file Meshing a hidden object will result in a visible mesh part even if a hidden mesh part with that name existed beforehand Hidden items are displayed with grey icons in the tree EM Software 4 Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 11 Items are hidden by selecting them and selecting Hide from the pop up menu or View Hide from the main menu These items can be shown again by selecting them in the tree and selecting Show from the pop up menu or View Show from the main menu If the selection contains visible and hidden items selecting Show Hide toggles the hidden state of each selected item Finally selecting View Show all in the main menu shows all hidden items independent of the current selection and the pop up menus Show all geometry and Show all meshes do the same for geometry and mesh parts respectively If a model is saved and reloaded all items become visible again 4 4 The tree The tree provides an alternative representation of the current model The top or contents tree contain
504. top level parts these items are not listed for parent objects Icons next to the items in the trees indicate their type properties and the application of transforms mesh properties etc The default names also indicate the type but after renaming for example Assembly1 to Antenna the icons become very useful The square icons next to dielectric names and regions indicate the colour of this medium in the 3D display Primitives Cuboid Flare cut off pyramid December 2005 FEKO User s Manual 4 12 WORKING IN CADFEKO Sphere Cylinder Cone Polygon Ellipse Parabolic surface Line Polyline curve Bezi r curve Elliptical arc Spline curve through points Helix or spiral Imported CAD body Surface body e g created with face copy or explode Curve edge wire body e g created with edge copy or explode Bj gt Ta ZO ZO N GO eV O Mesh part New constructions Boolean union Boolean intersection Ase Boolean subtraction Split Object created by spinning rotating parent Object created by sweeping extruding parent This geometry contains edges created by projecting other items onto it This geometry contains imprinted points 0 amp a Loft ruled surface created between two edges ie i ES Simplified geometry redundant items removed
505. tries as the first column the empty data points must be represented by the text NAN Frequency MHz mag S_11 mag1S_21 1 00000E 02 4 74462E 01 2 83472E 01 2 00000E 02 1 46055E 00 2 66604E 01 3 00000E 02 7 46769E 00 2 06073E 01 4 00000E 02 2 19462E 00 NAN 5 00000E 02 6 12814E 00 NAN For Smith chart data the first column must contain the phase in degrees and the next columns the amplitude 6 6 Exporting images 3D 2D Use File Export Image to export the current view to an image file Currently BMP JPG PNG XPM and EPS files are support The EPS files are vector based but for the 3D views it effectively uses bitmaps of the rendered screen It is important to ensure that the entire display is visible when exporting it to an image If another window covers part of the images it will also cover the exported image It is also possible to copy the figure to the MS Windows clipboard and to export animated AVI files from 3D view animations 6 7 Polarisation Far field polarisation can be calculated in a number of polarisations Since some of these are less familiar they are summarised here see also figure 6 4 e Total The total value independent of the polarisation e Vertical The vertical or Y component e Horizontal The horizontal or p component e LHC The left hand circularly polarised component The polarisation vector rotates counter clockwise when viewed at a fixed position in the direction o
506. tructure and the meaning is the same as with the other basis functions For the FEM the data of the tetrahedral volume elements is printed in a table like this DATA OF THE TETRAHEDRAL VOLUME ELEMENTS FEM December 2005 FEKO User s Manual 14 6 DESCRIPTION OF THE OUTPUT FILE OF FEKO no label xi inm y1 inm z inm nodes medium x2 in m y2 in m z2 inm faces x3 in m y3 in m z3 inm edges x4 in m y4 in m z4 in m volume in m m m 1 Unioni 2 3572E 02 1 0940E 02 1 4989E 02 1 2 3 4 air 1 3328E 02 6 4075E 03 2 6102E 02 1 2 3 4 1 1854E 02 1 4150E 02 1 6861E 02 2 3 4 5 7 2568E 03 2 5013E 02 1 4889E 02 1 3899E 07 2 Unioni 7 2568E 03 2 5013E 02 1 4889E 02 4 5 6 7 air 9 6795E 03 1 8920E 02 1 3166E 02 5 6 7 8 1 2531E 02 1 6999E 02 1 3380E 02 T 8 9 10 11 8 8380E 03 1 6914E 02 1 6150E 02 8 7909E 09 3 Unioni 7 2568E 03 2 5013E 02 1 4889E 02 4 5 6 8 air 9 6795E 03 1 8920E 02 1 3166E 02 5 9 10 11 1 2531E 02 1 6999E 02 1 3380E 02 7 8 13 10 14 1 2033E 02 1 9460E 02 1 0077E 02 8 8478E 09 With the provided header this information should be self explanatory Thereafter information follows regarding the number of basis functions DATA FOR MEMORY USAGE Number of metallic triangles 0 max triangles MAXNDR 62 Number of dielectric triangles 0 Number of FEM surface triangles 62 Number of metallic segments 37 max segments MAXNSEG 37 Number dielectr magnet cuboids 0 max cuboids MAXNQUA 0 Number of tetrahedral e
507. try for each solution at a given frequency For example if a solution is done with each of two sets of sources at a given frequency there will be two entries in this list The final group December 2005 FEKO User s Manual 6 10 WORKING IN POSTFEKO typically contains an entry for each card requesting output of the current data type For example if a model has three FE cards in the input file there will be three entries here 3D results can only be plotted as a function of position Note that for bi static RCS calculation a single angular sweep contains multiple solutions The Use continuous frequency checkbox is enabled if the BOF files contains adaptive continuous results See Chapter 13 Check this box and click the Sampling button to specify the interpolation frequency at which the results must be displayed The interpola tion frequency can be any frequency in the band not just the specific sample frequencies Frequency Solution Block no 1 1 2 116 667 MHz 3 133 333 MHz 4 166 667 MHz 5 200 000 MHz gt F Use continuous frequency Sampling Figure 6 3 The result selector 6 5 Displaying 2D results 3D displays give a good overview and provide insight but 2D graphs are required for quantitative display and data comparison The basic operation of 2D graphs are the same as for 3D displays but it has extra functionality First data from different models can be plotted on the
508. ts can be displayed in 3D or 2D with POSTFEKO POSTFEKO is used not only for post processing purposes but also to visualise the geometry of the FEKO model with excitations near field points etc before the actual FEKO run Note that the FEKO kernel components are available on PC s and a wide variety of work stations The GUI components CADFEKO EDITFEKO and POSTFEKO are available on PC s running MS Windows or Linux only All pre and post processing must thus be performed on a PC while the actual computationally intensive field calculations can be performed on the PC itself or on a workstation or parallel cluster as required FEKO includes a remote launching facility to make such a remote execution easy to use from within the GUI running on the PC First time users are advised to work through the Demo example and the Getting started manual located in the doc directory under the FEKO home directory the directory where FEKO has been installed It gives a basic introduction to FEKO and the different FEKO modules It is also recommended that new users read the General Comments Chapter 2 of this User s manual carefully Various simple FEKO examples that show the application of the different cards are dis cussed in the Examples guide EM Software amp Systems S A Pty Ltd December 2005 INTRODUCTION 1 3 1 2 Contacting your distributor or EMSS You can find the distributor for your region at www feko info conta
509. tself Select File Export Data This option exports the current 2D view to a text file that can be read by external programs such as MATLAB Note that this exports the raw data without scale factors or offsets If it is required to save the scaled data one must do a series calculation and then export the resulting value series POSTFEKO can also read data in this format using File Import Data POST FEKO queries the user if the data should be imported into a new or an existing graph POSTFEKO also queries the dB conversion factor for the data 20 for field quantities and 10 for power quantities and if the data is already in dB The data must be in columns separated by one or more spaces no commas The data in the second and higher columns are plotted against the first column The table below shows an example of a text file with data for two lines ready for import into POSTFEKO The first line consists of the bottom axis caption associated with the first column followed by a legend for each of the remaining data columns Note that the captions must be in the first row and each caption December 2005 FEKO User s Manual 6 16 WORKING IN POSTFEKO must be between quotation marks If no caption row is present POSTFEKO will still import the data first column gives the position on the bottom axis subsequent columns that on the left axis If any column except for the first column does not have the same number of data en
510. ty of Hamburg Harburg Germany December 2005 FEKO User s Manual 9 48 DESCRIPTION OF THE GEOMETRY CARDS 9 2 18 8 Import STL file PREFEKO can also import STL both ASCII and binary files STL files supports only triangular patches and these are all imported Also since the STL file makes no provision for any labels label selection is not supported The scale factor is supported IN Include an external file Import STL file y File name Es Scale factor An example of an ASCII STL file is SOLID CATIA STL PRODUCT FACET NORMAL 4 602166E 01 1 858978E 01 8 681260E 01 OUTER LOOP VERTEX 4 789964E 01 8 440244E 01 2 878882E 01 VERTEX 4 764872E 01 8 439470E 01 2 892018E 01 VERTEX 4 783065E 01 8 414296E 01 2 876983E 01 ENDLOOP ENDFACET FACET NORMAL 4 601843E 01 1 859276E 01 8 681367E 01 OUTER LOOP VERTEX 4 764872E 01 8 439470E 01 2 892018E 01 VERTEX 4 761175E 01 8 425569E 01 2 891001E 01 VERTEX 4 783065E 01 8 414296E 01 2 876983E 01 ENDLOOP ENDFACET ENDSOLID For the description of binary STL files please see http www ennex com fabbers StL asp http rpdrc ic polyu edu hk old_files stl_binary format htm 9 2 18 9 Import CADFEKO model file CADFEKO exports the mesh to a CFM file which is imported by an IN card in the default PRE file created by CADFEKO The options are similar to those of the other formats that PREFEKO can import EM Software 4 Systems S A Pty Ltd December 2005 DES
511. ty or 0 the value specified at the SP card is used This value is only used if the S parameters are requested with an SP card The vector of the voltage lies in the direction from the beginning of the segment to its end in the direction in which the segment was created by the BL card This is the direction of the current flow through the segment The internal EMF electromagnetic force of the impressed voltage source is in the opposite direction EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 13 10 2 5 A2 card With this card a voltage source is placed at a node between two segments or between a segment and a triangle ground plane or polygonal plate It is mostly used to feed wires attached to plates etc A2 Add a voltage source to a node New source Add to sources Select segment Set source position Source label see manual poo Magnitude of source V fit Phase of source degrees Coordinates of node S parameter impedance Ohm J Parameters New source New excitation replaces all previous excitations Add to sources Additional excitation is added to previous excitations Select segment When this item is selected the Source label field becomes active Here one specifies the label of the segment at which start point the source is located The excitation has to be located at a node either between two se
512. udes the selected parts along a specified vector or spins rotates them around a specified axis respectively These operations can only be applied to parts The sweep spin operation is applied separately to each selected parts If multiple parts are swept spun the resulting new parts have no relation to each other i e each one gets its own copy of the parameters and can be modified independently afterwards Only parts containing nothing but edges and or faces not solids or closed regions may be spun swept For surface bodies the body must have a single boundary which does not close on itself and no edge may be attached to more than two faces for example the T plate union in figure 4 13 is not allowed to be spun swept as the connecting edge is bordering three faces Sweeping or spinning an edge results in a surface while applying these operations to a face results in a solid When the Sweep operation is selected the Sweep geometry dialog allows specifying the vector in terms of a start and end point These fields accept standard point entry see EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 27 Figure 4 13 T plate example of an edge bordering three faces which means that it cannot be swept spun section 4 6 3 It is not possible to sweep bodies in a direction that is tangential to any of its edges or in the plane of its faces The Spin geometry dialog allows specifying the axis of
513. udes the functionality to display the relative amplitude of the con tributions due to the different UTD rays All results can be plotted in dB or on a linear scale as selected in the Scale group It is possible to add an offset and a scale factor to the data This is applied after converting to dB Adding a 60dB offset changes for example dBV to dBmV The minimum and maximum values used in the colour legend are specified on the Scale group If Manual limits is checked the slider bars in this group are disabled and exact values can be entered If unchecked the sliders control the extents between the minimum and maximum values in the selected data Selecting Instantaneous on any of these pages shows the results as a function of wt For wt 0 this is the real part and for wt 90 it is the imaginary part of the complex quantity Animation of results is usually found on the Options tab on each of these pages and is usually only available for Instantaneous results Also the results that can be displayed as arrows can generally only be displayed for Instantaneous results 6 4 2 3D result selection All result pages contain the result selection group shown in figure 6 3 Select the appro priate frequency from the first list Note that a new entry is added to this list each time the solution frequency changes Thus if solutions were done at 1 GHz 1 1 GHz and again at 1 GHz there will be three entries in the list The Solution list contains an en
514. ue should be used the values should be entered in the table below The keyword for this optimisation method is KONJUGIERTE_GRADIENTEN_VERFAHREN or CONJUGATE_GRADIENT_METHOD Quasi Newton method This optimisation function uses the Quasi Newton method by Davidon Fletcher Powell DFP or by Broyden Fletcher Goldfarb Shanno BFGS The gradient is determined at a starting point in the variable space The direction for the line search is then determined from the starting point and product of the negative gradient at this point and the unit matrix The length of the search step is established in a one dimensional minimisation process which is distinct from the Conjugated Gradient method both in the nature of the process and its accuracy At this newly established point in the variable space a new gradient is calculated From the new and previous gradients as well as the new and previous points in accordance with the DFP or BFGS formula for the metric an approximation of the inverse Hesse matrix is now applied instead of the unit matrix The product of this current approximation of the inverse Hesse matrix and the new negative gradient gives the direction for the next iteration The method is terminated if the new gradient is sufficiently small or when the current point is within a pre defined distance from the previous point December 2005 FEKO User s Manual 11 10 THE OPTIMISER OPTFEKO Optimisation Optimisation type Quasi Newton
515. umber of blocks This parameter indicates the number of blocks in the output file from FEKO that are to be read For each block i 1 Ng the first row is read and the gain directivity g in dB is extracted Rows per block This must be set to the number of rows that are to be read from each block i e the number of discrete points Vj pj when vary ing the angle Number of lines This parameter specifies the number of aim points that will be specified in the table below The parameter N is the line num ber within each block Either the target value or the range of values see parameter Min Max values above for each line should be entered into the table These values are either in dB optimi sation for gain directivity or represent the normalised radiation pattern in the range 0 1 Regarding the aim function used by FEKO we have to distinguish several cases In the following P j is the user specified aim radiation pattern with j in the range 1 Ng When the parameter Min Max values is selected these are denoted with Pnin j and Pmax j in the following OPTFEKO automatically uses a linear interpolation for points in between the Np specified points Should P 1 or Pnin 1 Pmax 1 not be defined by the user OPTFEKO assumes a value of zero both in the linear case also for gain directivity in dB This might not be correct thus it is advisable to always specify the desired values for the first angle The error function depends on
516. umber of iterations is given and the resulting residue from the iterative solving process of the matrix equation SnP file The Touchstone S parameter filename contains the number of ports in the model The extension is sip for a 1 port s2p for a 2 port and so on For 10 port and larger structures the p is dropped for example s12 for a 12 port The file contains a header following the character which specifies the frequency unit the parameter type the data format and the normalising impedance for all the ports This is followed by the data lines which may be repeated for multiple frequencies December 2005 FEKO User s Manual 10 68 DESCRIPTION OF THE CONTROL CARDS 1 port 2 port 3 port 4 port Om Ot y L821 2931 Sit LS21 2931 2841 S42 ZS 45832 gt 4842 y 28195 2513 L823 2533 L813 2993 S33 2943 S22 4822 Sial 4S14 S L S24 S3a 4834 Saal 2544 where S11 is the absolute value and 4511 the phase in degrees of the given parameter Note that the 2 port file is formatted on a single line and in a different order than for cases with more ports sph file This file is using the native SWE file format of TICRA as used in their code GRASP For all files except SnP and sph the data is in rows i e each new set of data is in a new row Complex numbers are given in the normal FORTRAN format Real Imagi
517. undary between mediums A and B Normal vectors of the triangles point from Ato B All tetrahedral and cuboidal volume elements following this card will have the properties of medium A Note that the outer medium extending to infinity must always be medium 0 Parameters Metallic triangles in a homogeneous medium If this option is selected then all the surface structures between this card and the next ME card are assumed to be fully contained inside the medium specified in the Medium for triangles segments dialog Triangles representing the surface of a dielectric body If this option is selected then all the surface structures created between this card and the next ME card are assumed to define the boundary between two media Note that the user needs to provide the names of the medium on both sides of the triangles The normal vector points from medium A to medium B Thus if we have a dielectric body of medium DIELECTRIC constructed such that all the triangle normals point outward we set medium A to for instance DIELECTRIC and B to 0 the number zero always represents the outer free space region Metallic triangles representing the surface of a dielectric body If this option is selected then all the surface structures created between this card and the next ME card are assumed to define a metallic boundary between two media The selection of the sides is the same as for the non metallic case discussed above De
518. unique the same medium name can be used for many different regions For Boolean unions between bodies where intersecting regions have conflicting material properties an Unknown medium is created automatically Initially the dialog shows the current state of the property for the selected item s If multiple regions are selected fields which are not the same for all dialogs are left blank These properties are not modified when changes are applied This allows for example modifying the mesh size for a number of different dielectrics simultaneously EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 33 4 8 1 Metal faces If a region is dielectric faces bordering it can be set as metallic by checking the Metal surface box on the Face properties dialog shown in figure 4 18 A Face properties 21x Mesh size IV Local mesh size Mesh size 0 2 Metal surface J7 Metal surface so toos Figure 4 18 The Mesh properties dialog for faces Note that faces bordering a metal region or those with free space on both sides are always metal and for these the Metal surface field is disabled However the property is persisted Hence if a dielectric region with a metal face is set to a metal solid all its faces become metal but if the region is set to dielectric again only the original metal face will again be metal The details tree uses icons to indicate the metal properties of a face If
519. ures 10 9 and 10 10 show the application of the equivalence principle to a planar aper ture In both figures there are the same number of field points along the two orthogonal directions When the Also sample along edges item is checked the first point lies at S1 with the following points in the direction of S2 as shown by the indices in figure 10 9 When it is unselected the pattern is as shown in figure 10 10 The normal vector is calculated from uz X tg with z and z as defined in the figure Figure 10 11 shows the dipole locations for a cylindrical aperture created from a data file containing field values for y from 20 to 80 in 10 increments and 5 values in the z direction When the Also sample along edges item is checked the samples extend up to the edges of the aperture the points and the effective aperture are shown in figure a When it is unchecked samples do not lie on the edges as shown in figure b Note that when using identical input data as for the case when the item is checked the z positions of the samples changed while in the y direction the size of the effective aperture is increased by 5 on both sides Figure 10 12 shows the dipole locations for a spherical aperture created from field values N3 1 N2 1 N3 N2 S3 Nen amp o o o o o o e o e o 0 0 0 0 e e e e e e e 0 3 N2 1 e e e e e e e 0 Us 2 N2 1 _2 N2 1 3 N2 e e e e e e 0 N2 1 _N2 2 2 N2 o e e e e e 0 3 4 5 6 N2 1 N2 o o e o o o
520. ussed normalisation aim function specification of values in the opt file but the case of the magnetic field is analogous one must just replace E by H and e by h in the formulas above If one wants to enforce to have only E but no Exs and E components then all one has to do is to change the two factors f and f which in a Cartesian coordinate system refer to the x and y components both to 1 0 so that these components are included in the aim function Both electric and magnetic fields can be optimised for by selecting the appropriate button When optimising both field simultaneously the meaning of Ng Ns and Nnorm is still the same as when optimising only E or H but for the component Neomp one can now specify this separately for the electric and magnetic field using Ne comp or Nh comp respectively There are now factors f which are used in the error function Ns fe 1 le1 5 5 et fea lezij es fes lesa e355 Hfr laos ARG fn lhaa ASTI fhs haii A3451 The table with the required field strength values has now also both E and H field values in one line EM Software 4 Systems S A Pty Ltd December 2005 THE OPTIMISER OPTFEKO 11 27 11 3 Running OPTFEKO Firstly the pre and opt files must be created as discussed above During optimisation new pre input files are continuously created by adding the string _opt_ and a sequen tially incremented number to the file name When for
521. ution The following data is given for each triangle VALUES OF THE CURRENT DENSITY VECTOR ON TRIANGLES in A m Triangle centre JX JY JZ number x m y m z m magn phase magn phase magn phase 1 944 000 056 1 644E 03 19 10 0 000E 00 00 3 716E 02 162 73 2 889 000 111 1 184E 03 163 01 0 000E 00 00 3 238E 02 157 26 3 944 000 222 4 709E 03 12 49 0 000E 00 00 2 784E 02 149 11 4 889 000 278 2 032E 03 170 73 0 000E 00 00 2 081E 02 119 69 5 944 000 389 4 285E 03 13 23 0 000E 00 00 2 083E 02 100 40 Current magnitude in the 3 corner points 3 850E 02 3 882E 02 3 457E 02 3 145E 02 3 169E 02 3 445E 02 3 143E 02 3 446E 02 2 197E 02 2 109E 02 2 234E 02 2 146E 02 2 106E 02 2 467E 02 2 291E 02 At the position x y z the current density vector J in the complex form is given The last three columns indicate the value for the surface current density in the three vertices of the triangles where the value is the average of the current at the vertices of all three adjacent triangles If the current is requested the charge on each triangle is also written to the output file Only the charge is given as the position of each triangle is the same as written for the currents VALUES OF THE SURFACE CHARGE DENSITY ON TRIANGLES in As m 2 Triangle SIGMA number magn phase 1 2 50469E 13 56 08 2 3 55072E 13 42 60 3 9 33040E 13 54 20 The current on the segments is written as VALUES OF THE CURRENT IN THE SEGMENTS in A Segment centr
522. utor EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 103 10 2 39 PS card This card is a general program control and can be used for instance to store the current expansion coefficients to a file or load them later again to speed up the solution It is important to be familiar with the solution process of the MoM to understand this card The solution of electromagnetic problems based on the MoM involves a setting up a system of linear equations which by default is solved using an LU decomposition and a subsequent backwards substitution This card can be used to save the matrix of the system of linear equations its LU decomposition or the solution vector which also includes PO currents etc Such elements can also be loaded again PS Control data structure Save read matrix elements No data files normal execution C Save matrix elements to mat file C Read matrix elements from mat file Read matfile if it exists else create it Save read LU decomposed matrix No data files normal execution Save LU decomposition to lud file C Read LU decomposition from lud file C Read lud file if it exists else create it Save read currents No data files normal execution Save currents to str file C Read currents from str file C Read strfile if it exists else create it Parameters Save read matriz elements Select t
523. vailable as variables in PREFEKO For example the variables n1234x n1234y and n1234z give the coordinates of the NASTRAN grid point with index 1234 Note that points are not included by default December 2005 FEKO User s Manual 9 40 DESCRIPTION OF THE GEOMETRY CARDS Each line in the 8 character column based format consists of one keyword such as GRID starting in column 1 From column 9 onwards follow 9 input fields with widths of 8 characters each Thus input field 1 uses columns 9 to 16 input field 2 uses columns 17 to 24 etc The ninth and last input field 9 ends at column 80 Below is a very simple NASTRAN example file consisting of a plate property 1 subdivided into eight triangles and a rod property 2 subdivided into two segments IF la pp ll pp P ID XXXXXXXX YYYYYYYY CEND BEGIN BULK GRID 1 0 0 0 0 0 0 GRID 2 0 50000 0 0 0 0 GRID 3 1 00000 0 0 0 0 GRID 4 0 0 0 50000 0 0 GRID 5 0 50000 0 50000 0 0 GRID 6 1 00000 0 50000 0 0 GRID 7 0 0 1 00000 0 0 GRID 8 0 50000 1 00000 0 0 GRID 9 1 00000 1 00000 0 0 GRID 10 0 50000 0 50000 2 00000 GRID 11 0 50000 0 50000 1 00000 CROD 9 2 5 11 CROD 10 2 11 10 CTRIA3 1 1 4 5 8 CTRIA3 2 1 4 8 7 CTRIA3 3 1 5 6 9 CTRIAS 4 1 5 9 8 CTRIA3 5 1 1 2 5 CTRIA3 6 1 1 5 4 CTRIA3 T 1 2 3 6 CTRIA3 8 1 2 6 5 ENDDATA For the node points FEKO also supports 16 character wide input fields The keyword GRID in columns 1 to 4 is followed by a star and three spaces The n
524. vailable only for metallic objects wires and surfaces and wire surface junctions e Any type of dielectrics except wire coatings or thin dielectric sheets are not allowed i e also no FEM or special Green s functions e When using waveguide ports then UTD or PO are not allowed in the same model Note however that in FEKO it is supported by means of the AR or AP cards to decompose a model say a horn antenna in front of a reflector into different sub problems and then waveguide feeds can be used See example_35 for an illustration of this decomposition technique Computing S parameters for waveguide ports with the SP card is supported Also multiple ports active and or passive can be present in the model S parameters are directly based on the waveguide impedance of the specific mode under consideration The reference impedance as specified at the SP card will not be used Examples for an application of waveguide feed can be found in the Examples Guide there waveguide_step S parameter computation for a waveguide discontinuity example_08 horn antenna and example_34 coaxial cable December 2005 FEKO User s Manual 10 54 DESCRIPTION OF THE CONTROL CARDS 10 2 19 BO card With this card a ground plane at z 0 can be specified for all computations following the BO card The reflection coefficient method is used Parameters BO Add a reflective ground C No reflection coefficient ground Refl
525. van tageous to add a small air region buffer around the actual dielectric object and also mesh this into tetrahedral elements i e also use the FEM there Then since in air the wavelength is larger one can use larger tetrahedral elements at the FEM MoM interface which reduces the memory requirement of the FEM MoM hybrid method for the coupling arrays This reduction is typically much higher than the extra memory required due to having more tetrahedral elements mesh of the extra air buffer zone In some cases accurate modelling of the geometry requires significantly finer mesh elements than specified by the guidelines above For low frequencies in particular the segmentation rule of is often much too coarse to yield a reasonable represen tation of the geometry Another case where finer discretisation may be required is where a wire runs parallel to a conducting plate If the wire is closer than to the plate the size of the triangles in the direction orthogonal to the wire should be similar to the distance from the wire to the plate in order to give an accurate representation of the surface charge distribution If the segmentation rules are not adhered to then the following errors and warnings will be reported by the FEKO kernel Warning Error Ratio of the segment length to the wavelength t gt 0 3 gt 0 5 Ratio of the segment radius to the segment length gt 0 3 gt 10 Ratio of the area of the triang
526. ve way to specify the con ductivity o the two loss terms are related by tan a and they have different frequency behaviour EM Software amp Systems S A Pty Ltd December 2005 DESCRIPTION OF THE CONTROL CARDS 10 55 It should be noted that it is not possible to calculate the fields below the ground plane i e it is not possible to calculate the fields in the region z lt 0 In addition all structures must be in the region z gt 0 If calculations inside the ground are required for example when there are structures below ground the exact Sommerfeld integrals GF card must be used When using a perfect electric or magnetic reflection coefficient ground plane structures can be arbitrarily close to the ground while remaining above it Segment end points and triangle edges lying in the plane of the ground plane will make electrical contact with a perfect electric ground plane For a perfect magnetic ground the boundary condition forces the current to zero at this point If real ground parameters are used the reflection coefficient approximation is more ac curate for structures further from the ground plane Typically structures should not be closer than about FEKO will give a warning if this is the case A dielectric ground real earth can only be used with bodies treated with MoM MLFMM PO FEM or the hybrid MoM PO i e the hybrid MoM UTD method cannot be used in the presence of a real ground Decembe
527. vector alpha 6 9209918e 00 7 8159398e 01 Minimal value of the aim function at no 31 7 2283000e 00 no of the last analysis 38 EM Software amp Systems S A Pty Ltd December 2005 THE PROGRAM TIMEFEKO 12 1 12 The program TIMEFEKO 12 1 Description With the program TIMEFEKO electromagnetic scattering problems can be solved in the time domain It is based on the program FEKO that does the calculation in the frequency domain and an FFT algorithm that transforms the data to the time domain For the excitation a number of different pulses have been defined and stored in the function library The functions available at present are described in section 12 3 1 The program TIMEFEKO is constructed in such a way that all the data in the output file out from FEKO are transformed i e in the input file the cards have to be specified in the correct way to ensure that the correct data is transformed Information on the correct card definitions is given in the following section The program TIMEFEKO uses two input files that have to be created by the user 12 2 The pre input file The input file with extension pre is the normal input file for PREFEKO in which the frequency has to be expressed symbolically While the program TIMEFEKO is running the frequency is constantly changed TIMEFEKO generates new pre files in which the actual numerical value of the frequency is assigned The user may use the DEFINED fu
528. ved with the model i e if the model is saved and loaded the lists will be cleared If an object is remeshed or a mesh is deleted the entire existing mesh is stored in the undo redo list This allows quick undo redo but can require significant memory if EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 5 large meshes are modified a few times Therefore it is recommended that the number of undo steps be reduced during extensive mesh manipulation See section 4 14 To obtain additional information on any component of the user interface click the What s this button and then click on the component This provides some help on a level between the very brief tool tip and the full online manual 4 2 2 Creating models Select File New to remove the entire geometry the mesh and any notes from the model and start a new model with a clean environment Similarly select File Open or File Save to open and save CADFEKO models Only the CFX file is required to open the model but when saving the model CADFEKO automatically saves the CFS file containing the workspace views workplanes etc and the CFM and PRE files used when solving models see section 4 15 The File Save as option saves the current model CFX CFS CFM and PRE files to a new name In addition to saving the files this option updates the PRE file to refer to the new CFM file File Export CFM file exports
529. when no accurate power values are required Since gain directivity are based on power they are then also possibly not very accurate Source power The total power Po in Watt i e the total power supplied by all the voltage sources or in the case of transmission lines the total power of all forward travelling waves Details of the various possibilities with the use of the PW card are shown in figure 10 27 no internal impedance internal impedance Zi Ca P P os P J P P Ww 3 Za O Za transmission line feed Transmission line with characteristic Pi Z impedance Z P 2 Figure 10 27 Possible applications of the PW card to determine the total power The options Total source power internal impedance and Total source power transmis sion line feed are only allowed for voltage sources the A1 A2 A3 A4 A7 and AE cards For models containing other sources such as dipoles and impressed currents the option Total source power no internal impedance should be used For plane waves No scaling use specified voltages must be used The power equations for different cases are discussed below Consider in general that there are N sources such as in an array antenna with open circuit voltages Us before the scaling operation where the parameter y lies in the range 1 N At each source there is an antenna input impedance Za as calculated duri
530. which defines a triangle or quadrangle by specifying the indices starting from 1 in the order the non linker vertices are specified of the vertices which form its corner points Vertices are defined as linkers by setting a value of 128 in the group code 70 field For linker vertices the coordinates are ignored Note that some old dxf versions do not contain linker vertices they cannot be imported Usually they do not contain mesh information The four integer numbers after the group codes 71 72 73 and 74 give the indices of corners of the triangle or quadrangle In the case of a triangle one of these is absent PREFEKO divides each quadrangle into two triangles along the shortest diagonal In addition to being able to import meshed polylines closed polylines can also be im ported These will be meshed into triangular patches during the import according to the meshing parameters set at the IP card December 2005 FEKO User s Manual 9 46 DESCRIPTION OF THE GEOMETRY CARDS 9 2 18 6 Import NEC model file PREFEKO also supports importing wire geometry from NEC models Note that NEC models usually consist of wire grid surfaces and it would be more efficient to convert the models to FEKO surfaces but this cannot be done automatically IN Include an external file Import NEC model file y IV Include segments File name ml Include all items Include only items with single label layer C Include items
531. with label 0 lie in the same plane they cannot illuminate each other Thus the first card states that label 0 is hidden from label 0 All triangles with label 1 are visible from all triangles with label 0 This is specified by the second VS card Since some triangles with label 2 are visible from some triangles with label 0 while others are hidden we cannot specify any information for this combination of layers However the plate with label 2 shadows all triangles with labels 3 and 4 and we may specify that these are hidden This is done with the third VS card Note that this card specifies a range of hidden labels Next we must specify which triangles are visible or hidden from all triangles with label 1 As for label 0 triangles with label 1 are not visible to each other specified by the fourth VS card All triangles with labels 0 and 2 are visible from all triangles with label 1 Since we have already specified the visibility between labels 0 and 1 we do not specify it again The fifth VS card then specifies that label 2 is completely visible from label 1 As for label 0 both labels 3 and 4 are hidden completely which completes the first six VS cards Next we look at label 2 As before we need not consider labels lower than 2 Also the label is hidden from itself as indicated by VS card number seven Next we state that label 3 is visible but we cannot specify anything about label 4 as only some of these triangles will be visible Sim
532. without FEMAP POSTFEKO should be used to verify the included geometry December 2005 FEKO User s Manual 9 36 DESCRIPTION OF THE GEOMETRY CARDS 9 2 18 3 Import special ASCII data file This option is used to import meshes stored in the geometry data file as specified below IN Include an external file import special ASCII data file see manual y Y Include segments IV Include polygons IV Include triangles File name Ce Ej Include all items C Include only items with single label layer C Include items with range of labels layers nclude structures with label Up to label Scale factor The ASCII format only supports segments triangles and polygons but all other non selection parameters discussed in the general section of the IN card above apply In this case the label is specified directly in the file and no conversion is required Dielectric triangles or metallic triangles which form the surface of a dielectric are created by preceding the IN card with the appropriate ME card In exactly the same way as is the case without the IN card The data of the segments triangles and polygonal plates are given in an ASCII file formatted as shown below There is no need to adhere to specific columns the data fields merely have to be separated by one or more spaces nk nd ns np nt x 1 y z 1 String_name x 2 y Q z 2 String_name x nk y nk z nk String_name d1 1
533. workplane dialog allows translation and or rotation using the three workplane axes U V N The workplane settings are updated with the result of the transformation any variables used in the settings will be lost Select Workplane Transform from the pop up menu of the 3D view or click the Transform workplane button on the 3D view toolbar The rotation angles are in degrees In CADFEKO radian angles are only used in the arguments and results of the trigonometric functions and their inverses If rotation is done around more than one axis CADFEKO uses Kardan angles Simply put this means the workplane is rotated first around the N axis then around the V axis and finally around the U axis See section 9 2 38 for more details The workplane cannot be transformed while the edit dialog is open or edited while the transform dialog is open The Zoom to extents operation which fits the workplane to the geometry is also disabled while editing the workplane 4 3 3 Snap mode Right click on the 3D view and select Snap to to specify how points will be selected from the 3D view via point entry see section 4 6 3 If Workplane is selected points are obtained from the workplane If Grid is selected the mechanism is the same but the values are rounded to the nearest grid values The values are rounded in the workplane coordinates and may not appear rounded in global coordinates for arbitrary workplane orientations With Geometry point or Mesh
534. xecuted limitation to avoid convergence problems If left empty the default value of 1000 will be used e For CableMod PCBMod Number of discrete frequencies 2 This field is only relevant when the CM card is used to create an isd file The results are written to the isd file for the number of discrete frequencies specified in this field e Starting ending frequency Defines the frequency range e Min frequency stepping Minimum increment between adap tive samples see the note below In order to obtain a continuous frequency response the adaptive frequency interpolation technique obtains the solution at a set of discrete frequency points They are automat ically placed for example using large frequency increments in regions with a smooth behaviour of the results and much finer frequency increments close to resonances Some times for example when using a frequency dependent mesh the FEKO results versus frequency may contain small discontinuities In these cases the adaptive algorithm can not converge It will continue to refine the frequency increment as it tries to fit a smooth curve through the discontinuity and will only stop when the Maz number of sample points is reached One may avoid this by setting the Frequency increment to the minimum al lowable separation distance between neighbouring frequency sample points The value of the Frequency increment must be smaller than the resolution required to solve for exampl
535. y Oneltwo sided gradient RP Floating point accuracy EPS 1 0616 Termination F FET Termination GTOL joes Search step length ALAM fi 0 Scale factor STPMX IS Termination TOL_X hoer Termination ALF_F hoes DFP 1 BFOS formula p IV Delta for all variables joa Values length o One two sided gradient FEKO can calculate either the one or two sided gradient Two sided gradients requires more FEKO runs per optimisation point but generally provides better starting points for subsequent runs Floating point accuracy EPS EPS is the accuracy to use for floating point calculations on the computer Once adjusted the value can be maintained For real variables the value is 3 0E 8 whereas for double variables it is 1 0E 15 Here double variables have been used Termination F F sets the factor with which the tolerance of the variable vector x should be larger than the accuracy EPS The product F EPS is the upper limit for the maximum difference in any component of the last two aim vectors It serves as a terminating condition for the whole process For maximum accuracy experience sug gests using a value of four If less accuracy is needed reaching the terminating condition can be accelerated by choosing F very large for example 2 5E10 The further apart the two last aim vectors the harder the condition to abort the procedure due to convergence of the variable vector Termination GTOL GTOL represents the size of t
536. y The user constructs a simple PRE file that imports the mesh in EDITFEKO run PREFEKO and then import the FEK file in CADFEKO This allows more control over the import process for example to only include certain labels 4 13 Mesh validation and editing 4 13 1 Mesh information Selecting Mesh Info from the main menu shows a histogram of the edge length distri bution and the number of the different elements in the current selection The selection may contain mesh parts labels or elements The spread gives an indication of the quality of the mesh and shows how many edges are over a desired length The numbers of the different elements indicate the problem size and the required run time EM Software amp Systems S A Pty Ltd December 2005 WORKING IN CADFEKO 4 41 4 13 2 Relabelling mesh elements A selection of mesh elements can be relabelled provided they are of the same type and be long to the same mesh part Since the full label is constructed as Assembly Part Label it is not possible to relabel elements on different parts Note that the individual elements not the labels must be selected see section 4 11 Labels are used to reference specific elements when setting up the control parameters in EDITFEKO To specify unique properties on an element or collection of elements those elements need to be relabelled As an example consider a simple wire monopole attached to a plate created as Unioni The resulting mesh conta
537. y the distance between the points S1 and 3 For elliptical cross sections this is the length of one half axis and the other one is Scale second half axis times this length Example of HE card usage The two coils shown in figure 9 15 are created using the HE card Figure 9 15 HE card examples the coil on the right is coiled in the left handed direction These examples are found in demo_HE1 pre EM Software 4 Systems S A Pty Ltd December 2005 DESCRIPTION OF THE GEOMETRY CARDS 9 33 9 2 18 IN card This card is used to include external files These files may be other pre files which are included as if they were part of the master file or mesh data files containing wire segments triangles quadrangles tetrahedral volume elements and or polygonal plates in FEMAP neutral an ASCII format NASTRAN meshed AutoCAD dxf NEC model Concept model STL PATRAN neutral or ANSYS cdb files Some fields are common to more than one option File name The name of the file This parameter is required for all import options The filename may contain directory names as well for example myfiles include inc and will have different exten sions for the various import options Both and are allowed on Windows and UNIX systems Include segments Check this item to include all wire segments that match the label selection See below Include triangles Check this item to include surface triangles Include quadrangles C
538. y using the parameters y 360 and a 360 Examples of TO card usage The toroidal segment which is shown in figure 9 40 is generated using a TO card This card can also be used to generate the toroidal segment with an elliptical cross section as shown in figure 9 41 Figure 9 41 Example for the TO card with an elliptical cross section from demo_T02 pre Note that it is stretched in the direction of the y axis i e it is elliptical in the y plane It is also elliptical in the a plane when y 90 but it is circular in the a plane when y 0 December 2005 FEKO User s Manual 9 96 DESCRIPTION OF THE GEOMETRY CARDS 9 2 40 TP card With this card points previously defined with the DP card can be translated rotated and or scaled relative to the origin TP Transform point Include by label V Use label selection Move all points starting from label 12 iY ending at label a Label increment for moved points zz Rotation around the x axis Lo o Rotation around the y axis kz Rotation around the z axis ss Translation along the xaxis ri Translation along the y axis Translation along the z axis Scaling in E x direction i y direction M zdirection Scale factor after translation Parameters Use label selection If this option is not checked then the TG card applies to all the previously defined points If this option is checked then a label selective processing

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