Home

FEKO Examples Guide

Contents

1. Keywords dipole radiation pattern far field input impedance This example demonstrates the calculation of the radiation pattern and input impedance for a simple half wavelength dipole shown in Figurel 1 The wavelength A is 4 m approximately 75 MHz the length of the antenna is 2 m and the wire radius is 2 mm Figure 1 1 A 3D view of the dipole model with a voltage source excitation symmetry and the far field pattern to be calculated in CADFEKO are shown 1 1 Dipole Creating the model The steps for setting up the model are as follows e Define the following variables lambda 4 Free space wavelength freq c0 lambda Operating frequency h lambda 2 Length of the dipole e Create a line primitive with the start and end coordinates of 0 0 h 2 and 0 0 h 2 e Define a wire port at the centre of the line e Add a voltage source to the wire port e Set the frequency to the defined variable freq July 2011 FEKO Examples Guide DIPOLE EXAMPLE 1 2 Requesting calculations This problem is symmetrical around the z 0 plane All electric fields will be normal to this plane and therefore the symmetry is electrical The solution requests are e Create a vertical far field request 180 lt lt 180 with 0 where and denotes the angles theta and phi Meshing information Use the standard auto mesh setting with wire segment radius equal to 2e 3 CEM validate After the mo
2. Figure 7 3 A full 3D plot of the antenna gain transparent in the figure to allow for visibility of the geometry and the curve of the far field pattern The currents on all elements wire segment and surface triangles are shown in Figure 7 4 The currents are indicated by the geometry colouring based on the legend colour scale This allows identification of points where the current is concentrated The currents are displayed in dB and the axis range has been manually specified The phase evolution of the current display may be animated as with many other results displays in POSTFEKO on the Animate tab on the ribbon Surface current dBA4 m 60 40 0 Sosooooo oscosooooo 0an Figure 7 4 3D view of the current on the ground plane of the monopole antenna July 2011 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND 8 1 8 Yagi Uda antenna above a real ground Keywords antenna Yagi Uda antenna real ground infinite planar Greens function optimi sation In this example we consider the radiation of a horizontally polarised Yagi Uda antenna consisting of a dipole a reflector and three directors The frequency is 400 MHz The antenna is located 3 m above a real ground which is modelled with the GreenSs function formulation Note that the model provided with this example includes a basic optimisation The optimisation is set up such that the optimal dimensions of the antenna may be determined to ach
3. Nearfield E Field V m RCS m 2 E Field 1 0 0 8 0 6 0 4 0 2 0 0 2 0 1 5 1 0 0 5 0 0 0 5 1 0 1 5 2 0 z m Exact a FEKO Figure 4 2 Near field along the Z axis Bistatic radar cross section 1 0 1 0 01 0 001 0 0001 Exact 0 00001 FEKO 0 000001 0 30 60 90 120 150 180 Theta deg Figure 4 3 Bistatic radar cross section of the dielectric sphere July 2011 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY 5 1 5 Shielding factor of a sphere with finite conductivity Keywords shielding EMC plane wave near field finite conductivity FEM A hollow sphere is constructed from a lossy metal with a given thickness and excited by an plane wave between 1 100 MHz Near fields at the centre of the sphere are calculated and used to compute the shielding factor of the sphere The results are compared to values from the literature for the case of a silver sphere with a thickness of 2 5nm Figure 5 1 shows a 3D view of the sphere and the plane wave excitation in the CADFEKO model Figure 5 1 A 3D view of the sphere with a plane wave excitation The CADFEKO preview of the plane wave excitation and the symmetry planes are also shown on the image 5 1 Finite conductivity sphere Method of Moments Creating the model The steps for setting up the model are as follows e Define the following variables rO 1 Radius of sphere f_min 1e6 Lo
4. e Create the bottom dielectric layer by using a cuboid whose centre is located at 0 0 0 The cuboid has a width of grnd_w a depth of grnd_1 and a height of d_a Label the cuboid bottom_layer July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 3 e Create the top dielectric layer by using a cuboid with its base centre at 0 0 0 The cuboid has a width of grnd_w a depth of grnd_1 and a height of d_b Label the cuboid top_layer e Union all of the geometry components e Set the bottom region medium to bottom_layer and the top region medium to top_layer e Ensure that the patch microstrip line the feed port and the ground plate are all set to PEC e Add and edge port between the two split components of feedPort Let the positive face correspond to the face attached to the microstrip line Add a voltage source to the port with the default source properties e In order to obtain accurate results whilst minimising resource requirements some local mesh refinement is necessary on several of the geometry parts Set local mesh refinement of lambda_b 40 on the patch edges Set local mesh refinement of ap_w 0 7 aperture edges e Set the continuous frequency range from f_min to f_max Requesting calculations Request a full 3D far field Magnetic symmetry may be applied to the plane at x 0 Meshing information Use the standard auto mesh setting Note that local mesh refinement was used on so
5. Reflection coefficient dB e S2P Network 50 130 132 134 136 138 140 142 144 146 1 48 1 50 Frequency GHz Figure 26 2 The reflection coefficient S11 of the dipole before and after application of the feed match ing Both the s parameter and SPICE networks are shown July 2011 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS 27 1 27 Subdividing a model using non radiating networks Keywords network S parameters Touchstone input impedance far field patch feed net work non radiating network A right hand circularly polarised patch antenna at 2 4 GHz is simulated in two ways The problem is first divided so that the feed network is characterised save S parameters to a Touchstone file and then the Touchstone file is used as a non radiating network to feed the patch The two models feed network and patch antenna are then combined so that the full simulation model contains feed and patch is performed The input impedance as well as the simulation time and memory required for the two methods are compared We will see that subdividing the problem greatly reduces the required resources but the field coupling between the feed network and the patch is not taken into account and causes some variation in the results The steps required to create the model is not part of the this example However some important points regarding the creation process will be highlighted Figure 27 1
6. e tand 0 005 Dielectric loss tangent The following variables derived from the above variables are used in the model construction e alpha arcsin D 2 F Included angle to edge of lens e arclength alpha F Arc length to edge of lens e gLO arclength 10 Mesh variable e n sqrt epsr Refraction index e T 2 F sqrt 4 F D 2 n 1 Lens thickness e v0 F T n 1 Ellipse offset distance e u0 sqrt n 1 vO Ellipse minor axis length e w0 n vO Ellipse major axis length A dielectric medium named Glass is defined and the relative permittivity and loss tangent are set to the variables epsr and tand respectively The lens is constructed by spinning the generator curve S through 360 After spinning the Lens part is simplified to remove the generator curve from the lens faces The generator curve consists of the union of the two arcs S1 and S2 Each arc is constructed from the intersection of e asolid cylinder with diameter D and length F 2 T its axis aligned along the z axis and e a 90 elliptical arc To construct the spherical and elliptical arcs the work plane is aligned with x y plane e S1 Spherical arc is centered at 0 0 0 and the x radius and y radius are both equal to E The start and end angles are 90 and 180 respectively e S2 Elliptical arc is centered at 0 v0 0 and the x radius and y radius are equal to u0 and vO n respectively The start and end angl
7. ee O Sees EE IS i i I 1 i L dc sie ab 4 S A I I l 1 if 1 ite ob hb D j 1 e I 1 1 I I l I I l A E aaa ae Y eee eee E if 1 1 a if i l EE ee ee Pe ee meee Lo g I I l H I if 1 1 iF 1 1 1 ae eee CA A eee a 1 1 1 1 I 1 l 1 if 1 1 I I 1 1 l H 14 LA 5 H E hh el nS a a T e I I I I I i i I I I I i 1 I I i I I l l I I I I if 1 1 p E A A 2 888 R 88 lt 8B uyo eouepeduu Frequency MHz Figure 32 3 Real and imaginary part of the input impedance of the windscreen antenna FEKO Examples Guide July 2011 A TIMEFEKO EXAMPLE 33 1 33 A TIMEFEKO example Keywords TIMEFEKO time domain Fourier transform In Figure 33 1 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 are to be calculated y Figure 33 1 Cube with side lengths of 1m The input file Cube pre is reproduced below July 2011 FEKO Examples Guide A TIMEFEKO EXAMPLE 33 2 TIMEFEKO example pre file A metallic cube with side lengths im Only 1 8 of the cube is generated explicitly the rest of the cube is generated by means of symmetry Normally TIMEFEKO wi
8. Shielding Factor dBV m 0 10 20 30 40 50 60 70 80 90 100 Frequency MHz Figure 5 3 Shielding of the magnetic field July 2011 FEKO Examples Guide EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID 6 1 6 Exposure of muscle tissue using MoM FEM hybrid Keywords exposure analysis FEM MoM hybrid method SAR dielectric losses This example considers the exposure of a sphere of muscle tissue to the field created by a dipole antenna between 0 1 1 GHz The geometry of the example is shown in Figure 6 1 gt Figure 6 1 Sphere of muscle tissue illuminated by a dipole antenna 6 1 Dipole and muscle tissue Note There is an air layer used around the sphere of muscle tissue to reduce the number of triangle elements required on the boundary between the FEM and MoM regions This is not strictly necessary but if this method is not used the resource requirements for the computation of the interaction between the FEM and the MoM regions would be higher without an improvement in the accuracy of the results Creating the model The steps for setting up the model are as follows e Define the following variables f_min 100e6 Minimum simulation frequency freq 900e6 Operating frequency f_max 1e9 Maximum simulation frequency d 0 1 Distance between the dipole and muscle sphere rA 0 03 Radius of the outer sphere rM 0 025 Radius of the inner sphere lambda c0 freq Free sp
9. 0 0 0 and 0 0 lambda 4 and rename as monopole e Union the wire and the ground e Add a wire segment port on the line The port preview should show the port located close to the ground if this is not so change the port position between Start and End e Add a voltage source to the port 1 V 0 e Set the frequency equal to freq July 2011 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE 7 2 Requesting calculations Two planes of magnetic symmetry are defined at the x 0 plane and the y 0 plane The solution requests are e One vertical far field pattern is calculated 180 lt 0 lt 180 and 0 e A full 3D far field pattern is also calculated e All currents are saved to allow viewing in POSTFEKO Meshing information e Use the standard auto mesh setting e Wire segment radius lambda 1ie 5 CEM validate After the model has been meshed run CEM validate 7 2 Results A polar plot of the total gain in a vertical cut is shown in Figure 7 2 Gain Theta cut Phi 0 dB 210 180 150 Figure 7 2 Polar plot of the total gain in a vertical cut A full 3D pattern is also calculated and shown in Figure 7 3 As the antenna has an omnidirec tional pattern in the p plane we can use coarse steps in The far field gain is shown slightly July 2011 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE 7 3 Total Gain L6 vaD SOOO omme SV 2000
10. 2375 Length of one arm of the reflector element in wavelengths 2265 Length of one arm of the driven element in wavelengths 2230 Length of one arm of the first director in wavelengths 2230 Length of one arm of the second director in wavelengths 3 Spacing between the reflector and driven element in wavelengths 3 Spacing between the driven element and the first director in wavelengths 3 Spacing between the two directors in wavelengths r 0 00225 lambda Radius of the elements e Create the active element of the Yagi Uda antenna Set the Start point as 0 O L1 lambda and the End point as 0 0 L1 lambda July 2011 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA 9 2 e Add a port on a segment in the centre of the wire e Add a voltage source on the port 1 V 0 e Set the incident power for a 50 transmission line to 1 W e Create the wire for the reflector Set the Start point as SO lambda 0 LO lambda and the End point as SO lambda 0 LO lambda e Create the two directors Set the Start point and End point for Director1 as the following Si lambda 0 L2 lambda and S1 lambda 0 L2 lambda respectively For Direc tor2 set the Start point and End point as S1 S2 lambda 0 L3 lambda and S1 S2 lambda 0 L3 lambda respectively e Set the frequency to freq Requesting calculations The z 0 plane is an electric plane of symmetry Th
11. GF Fin substrate SEP 15 20 25 3 0 3 5 4 0 Frequency GHz Figure 15 5 S5 in dB of the microstrip filter on an infinite and finite substrate from 1 5 GHz to 4 GHz July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A UTD GO PO PLATE 16 1 16 Dipole in front of a plate modelled using UTD GO and then PO Keywords UTD PO GO dipole radiation pattern far field electrically large plate A dipole in front of an electrically large square plate is considered This simple example illustrates the differences in required meshing between UTD GO and PO The results from all three these methods are compared to the full MoM solution First the dipole and the plate is solved with the MoM The plate is then modified so that it can be solved with UTD GO and later PO and LE PO The MoM UTD MoM GO and MoM PO hybrid solutions demonstrated here are faster and require less resources than the full MoM solution These approximations can be used to greatly reduce the required solution time and resources required when they are applicable 16 1 Dipole in front of a large plate Figure 16 1 A 3D view of the dipole in front of a metallic plate Creating the model The steps for setting up the model are as follows e Define the following variables d 2 25 Separation distance between dipole and plate 3 lambda 4 h 1 5 Length of the dipole lambda 2 a 4 5 Half side length of plate
12. July 2011 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA 9 4 Far Field Yagi_Pattem_Optimisation Yagi_Pattem_Optimisation_optimum 10 0 Oo 3 8 10 20 30 0 30 60 90 120 150 180 Phi deg Total Gain Frequency 1 GHz Theta 90 deg Figure 9 2 The vertical polarised gain of the Yagi Uda antenna before and after optimisation July 2011 FEKO Examples Guide MICROSTRIP PATCH ANTENNA 10 1 10 Microstrip patch antenna Keywords microstrip patch antenna dielectric substrate pin feed edge feed optimisation A microstrip patch antenna with different feed methods is modelled The dielectric substrate used is modelled with a finite substrate and ground using the surface equivalence principle or SEP as well as an infinite planar multilayer substrate and ground using a special Green s func tion The simulation time and resource requirements can be greatly reduced using an infinite plane although the model may then be less representative of the physical antenna The two different feeding methods considered are a pin feed and a microstrip edge feed In this example each model builds on the previous one It is thus recommended that all the models be built and considered in the order that they are presented If you would like to build and keep the different models start each model by saving the model to a new location Note that the model provided with this exampl
13. coordinate system Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY 5 4 5 3 Results The subject of interest is the shielding capability of the sphere with respect to the incident electric and magnetic fields In other words the ratio between the field measured inside the sphere and the field incident on the sphere is calculated The incident field strength was set as E 1 V m From the wave impedance for a plane wave in free space the incident magnetic field can be calculated E 1 H 2 6544 x 10 A m No 376 7 The shielding factor is therefore E S 20xlog dB Ei S 20 dB z x 8 Hi Figures 5 2 and 5 3 respectively shows the shielding of the electric and magnetic fields as a result of a sphere with the finite conductivity properties provided Shielding Factor E Field E Shielding MoM e E Shielding FEM Shielding Factor dBV m 0 10 20 30 40 50 60 70 80 90 100 Frequency MHz Figure 5 2 Shielding of the electric field July 2011 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY 5 5 Shielding Factor H Field H Shielding MoM e H Shielding FEM
14. is required to be greater than Mask_min and less than Mask_max A weighting of 10 is assigned to the Lower limit goal The weighting that should be used depends on the goal of the optimisation 9 2 Results The radiation pattern calculated in the E plane of the antenna is shown in Figure 9 2 for both the initial design and the antenna resultant after the optimisation process The directivity in the back lobe region between 62 and 180 degrees has been reduced to around 7dB while the directivity over the main lobe region between O and 30 degrees is above 8dB Note that the graph shows the vertically polarised directivity plotted in dB with respect to The extract below from the optimisation log file indicates the optimum parameter values found during the optimisation search Optimisation finished Standard deviation small enough 9 942464375e 03 Optimum found for these parameters 10 2 401344019e 01 12 2 240657178e 01 13 2 165143818e 01 11 2 361475900e 01 s0 2 611380774e 01 s1 2 391776878e 01 s2 3 197788856e 01 Optimum aim function value at no 284 1 699609394e 01 No of the last analysis 289 Sensitivity of optimum value with respect to each optimisation parameter i e the gradient of the aim function at 1 variation from the optimum Parameter Sensitivity 10 7 421936000e 20 12 1 129663313e 21 13 8 538646147e 19 11 4 996750389e 20 sO 1 396064830e 18 s1 9 884080724e 17 s2 4 465638114e 18
15. method to be used on the plate must be changed This change is made by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Physical optics PO always illuminated The always illuminated option may be used in this case as it is clear that there will be no shadowing effects in the model With this option the ray tracing required for the physical optics solution can be avoided thereby accelerating the solution Requesting calculations No changes are made to the solution requests for the MoM PO case As with the MoM model the two planes of symmetry should be used to accelerate the solution speed and reduce resources Meshing information Use the standard auto mesh setting with the wire radius set to rho The auto mesh feature takes the solution method into account CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 16 5 Comparative results The total far field gain of the dipole in front of the PEC plate is shown on a dB polar plot in Figure 16 2 The MoM UTD MoM PO and full MoM reference solution are shown To obtain the large element PO LE PO models set the solution method from Physical optics PO al ways illuminated to Large Element Physical optics LE PO always illuminated and save the PO exa
16. 3 Dipole and dielectric cube The calculation requests are the same as the previous model Extending the model The model is extended with the following steps performed sequentially e Create a dielectric with label diel and relative permittivity of 2 e Set the region of the cuboid to diel e Set the face properties of the cuboid to default e Delete the lossy_metal metallic medium Meshing information e Use the standard auto mesh setting e Wire segment radius 2e 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings notes and errors Please correct error before running the FEKO solution kernel 2 4 Comparison of the results The gain in dB of all three models are shown on a polar plot in Figure 2 2 We can clearly see the pronounced scattering effect of the PEC and lossy metal cube with very little difference between their results We also see that dielectric cube has a very different effect The dielectric cube results in an increase in the direction of the cube July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE 2 4 150 180 210 Dielectric PEC e Lossy Metal Figure 2 2 A comparative polar plot of the requested far field gain in dB July 2011 FEKO Examples Guide RCS OF A THIN DIELECTRIC SHEET 3 1 3 RCS of a thin dielectric sheet Keywords RCS thin dielectric sheet TDS plane wave The electrically thin dielectric pla
17. Create a new dielectric medium named Glass with a dielectric constant of 7 0 and loss tangent of 0 02 e Create a layered dielectric with a single layer of type Glass that is 0 00335 m thick The name of the layered dielectric should be WindscreenLayers e Create a new windscreen definition similar to a dielectric that uses the WindscreenLayers layer definition and has zero offset Offset L A zero offset means that the location of the reference triangles are used to define the top surface of the windscreen e Import the Parasolid geometry for the windscreen windscreen_rear x_b and rename the imported geometry to Windscreen Note that the windscreen geometry should not unioned with the car and the antenna since the windscreen reference triangles do not form part of the MoM solution Select all the faces of the windscreen and set their solution method on the Properties dialog of the face to be Windscreen These are are the wind screen reference elements It is also recommended that the windscreen elements also have a local mesh refinement of 0 1 this will not influence the simulation time e Select all the wires of the antenna and set their solution method to be Windscreen These are windscreen active elements and the offset is set to zero the elements positioned on the top layer of the windscreen on the outside e Also select the faces bordering the windscreen reference elements and set their solution method to be active windscreen e
18. IN A STEPPED WAVEGUIDE SECTION 20 2 12 12 Length of the X section meshsize lambda 6 local mesh size e Create the Ku band waveguide section with its base corner at a1 2 11 b1 2 with a width of a1 a depth of 11 and a height of b1 e Create the X band waveguide section on the positive y axis Set its base corner at a2 2 0 b2 2 with a width of a2 a depth of 12 and a height of b2 e Union the two cubes and then simplify the model e Set the regions inside the cubes to free space e Delete the face between the two waveguides e Set a local mesh refinement of lambda 15 on the faces that form the ports of the wave guide local mesh size e Apply waveguide ports to both faces Port1 and Port2 e Rename the faces that form the waveguide to Port1 and Port2 respectively e Confirm that the propagation direction of the waveguide excitation is into the waveguide e Rename the top level geometry to Waveguide e Set the frequency to be continuous from 9 4872 GHz to 15 GHz Requesting calculations Magnetic symmetry in the x 0 plane and electric symmetry in the z 0 are used The solution requests are e S parameters calculation are requested Mode TEO1 on both ports Meshing information Use the standard auto mesh setting Note that a special local mesh size of lambda 15 is applied to the Port1 and Port2 faces that are used for defining the waveguide ports CEM validate After the model has been meshe
19. descriptions are not intended to be complete step by step guides that will allow exact recreation of the models for simulation This document rather presents a guide that will help the user discover and understand the concepts involved in various applications and methods that are available in FEKO while working with the provided models In each example a short description of the problem is given the model creation is discussed further information may be found in the notes editor window of the model files themselves and some results are presented July 2011 FEKO Examples Guide INTRODUCTION 2 More examples This set of examples demonstrate some of the capabilities and usage of FEKO For more step by step examples please consult the Getting started guide Also consult the FEKO website for more examples and models specific documentation and other FEKO usage FAQ s and tips Contact information You can find the distributor for your region at http www feko info contact htm Alternatively for technical questions please send an 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 lwww feko info July 2011 FEKO Examples Guide DIPOLE EXAMPLE 1 1 1 Dipole example
20. following variables r0 1 Radius of sphere r1 1 2 Radius of FEM vacuum sphere f_min 1e6 Lower operating frequency f_max 100e6 Upper operating frequency d 2 5e 9 Thickness of the shell sigma 6 1e7 Conductivity of silver July 2011 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY 5 3 e Create a new metallic medium with conductivity set equal to the variable sigma Label the medium lossy_metal e Create a new dielectric medium with the default properties of free space Label the medium air e Create a sphere at the origin with radius set equal the defined variable roO e Create another sphere at the origin with radius set equal the defined variable r1 e Set the region of both spheres to air e Set the medium type of the inner sphere s face to Lossy conducting surface Choose lossy_metal as the medium and set the thickness equal to the variable d e Union the two spheres e Set the solution method for the regions to FEM Finite Element Method e Create a single incident plane wave with direction set to 9 90 and p 180 e Set the frequency to calculate a continuous range between f_min and f_max Requesting calculations In the X 0 plane use geometric symmetry In the Y 0 use magnetic symmetry and in the Z 0 plane use electric symmetry The solution requests are e Create a single point near field request in the centre of the sphere Use the Cartesian
21. horn waveguide impressed field pin feed radiation pattern far field A pyramidal horn antenna for the frequency 1 645 GHz is constructed and simulated Figure 14 1 shows an illustration of the horn antenna and far field requests in CADFEKO h Figure 14 1 A pyramidal horn antenna for the frequency 1 645 GHz plane of symmetry shown In particular we want to use this example to compare different options available in FEKO to feed this structure Four methods are discussed in this example e The first example constructs the horn antenna with a real feed pin inside the waveguide The pin is excited with a voltage source Figure 14 2 Wire pin feed e The second example uses a waveguide port to directly impress the desired mode in this case a TE mode in the rectangular waveguide section e The third example uses an impressed field distribution on the aperture While this method is more complex to use than the waveguide port it shall be demonstrated since this tech nique can be used for any user defined field distribution or any waveguide cross sections which might not be supported directly at the waveguide excitation Note that contrary to the waveguide excitation the input impedances and S parameters cannot be obtained using an impressed field distribution July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 2 Figure 14 3 Waveguide feed Figure 14 4 Aperture feed e The fou
22. is an illustration of RHC patch antenna with the feed network A Figure 27 1 The model of a RHC patch antenna with feed network 27 1 Feed network The feed network consists of a branch line coupler that divides the power evenly with 90 degree phase difference between the outputs The output signals are then extended to the patch feed interfaces using microstrip transmission lines The entire system is designed in a 120 Q system system or reference impedance Creating the model The steps for setting up the model are as follows e Define a new dielectric named RogersDuroid5870 Relative dielectric constant of 2 2 and tan 0 0012 July 2011 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS 27 2 e Add an planar multilayer substrate infinite plane with a height of 2 5 mm and dielectric material RogersDuroid5870 A perfect electric ground should be placed on the bottom of the substrate this is the default e Create the branch coupler for an output impedance of 120 Q e Create the microstrip transmission line sections that connect the branch coupler to the patch antenna This model does not contain the antenna but later this model is imported into the antenna model to do the complete simulation e Create four microstrip ports on the four terminals of feed structure Name the ports by number 1 to 4 starting at the input port then the two output ports that will connect to the patch and then th
23. is clear that the required resources are decreased by using approximations We see that solving the problem using the MLFMM requires more than 3 Gb of main memory and more than two hours to solve By simply using LE PO as solution method for the reflector the memory requirement and solution time is greatly By sub dividing the model into equivalent source models resource requirements can be reduced even further Table 25 1 Comparison of resources using different techniques for large models Model RAM Time s Total Time s MLFMM benchmark 3 373 Gb 6418 8570 MoM Horn LE PO Reflector 158 Mb 78 78 Generate AP amp AS source data 158 Mb 116 AP source LE PO Reflector 7 63 Mb 334 450 Spherical source LE PO Reflector 1 Mb 6 122 The differences in the results is shown in figure 25 2 and 25 3 respectively We can see that there is a very good comparison between the results The reason for the difference in the results is due to the fact that coupling between the horn and the reflector is only taken into account for the MLFMM solution The aperture source solution accuracy can be increased by increasing the number of near field points but this also increases the required solution time Although there is no restriction on the size of LE PO triangles it must be remembered that the geometry must be accurately meshed For example had a flat plate been used only two triangles would have been required t
24. on received power in W retrieved from a power graph in POSTFEKO or from the out file the received power is given at the end of each frequency after the table titled Summary of losses By setting the transmitting antenna power to 1 W on the power settings tab only the received power need to be recorded The coupling is then related to the received power by Received a Coupling gg 10 log10 l 1 24 3 The reference model In Full_Model cfx the full model including both horns and the plate is set up Here symmetry is also used in the xz and x y planes An impressed pattern point source and a receiving antenna are placed at 21 6 cm away from the origin on the x axis and at 60 wavelengths plus 21 6 cm form the origin respectively The coupling between the antennas is computed directly using an S parameter request This can then be viewed in an S parameter graph in POSTFEKO CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 24 4 Results The received power at the ideal receiving antenna is extracted from POSTFEKO Figure 24 2 shows the fully calculated model compared to the point source approximation It can be seen that the results match reasonably well where the differences can be attributed to the point source approximation July 2011 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTEN
25. parameters for this model must be calculated CEM validate After the model has been meshed run CEM validate Correct any warnings and errors before running the FEKO solution kernel Note that during the FEKO solver run the following warning may be displayed Inhomogeneous segmentation for triangles This warning is due to the occurrence of both very large and small triangles in the rotor of the helicopter This warning may be ignored for this example July 2011 FEKO Examples Guide ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT 22 2 22 2 Results This example requires considerable time to solve as shown in the extract below from the text out file These resource requirements both time and memory for the MLFMM solution in the MOM are however considerably smaller than would be the case for the full MoM solution The resource requirements are further reduced in this example by the application of the CFIE formulation to the closed PEC structure of the helicopter In this case the use of the CFIE requires 30 less memory resources and halves the simulation time required when compared with the default EFIE solution SUMMARY OF REQUIRED TIMES IN SECONDS CPU time runtime Reading and constructing the geometry 2 910 2 001 Checking the geometry 0 760 0 819 Initialisation of the Greens function 0 000 0 000 Calcul of coupling for PO Fock 0 000 0 017 Ray launching phase of GO 0 000 0 000 Calcul of the FMM transfer function 13
26. rho 0 006 e The wire dipole is a distance d from the plate in the U axis direction The dipole is h long and should be centred around the U axis Create the dipole line primitive by entering the following 2 points d 0 h 2 d 0 h 2 July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A UTD GO PO PLATE 16 2 e Create the plate by first rotating the workplane 90 degrees around the V axis e Create the rectangle primitive by making use of the following rectangle definition method Base centre width depth Enter the centre as 0 0 0 and the width 2 a and depth 2 a e Add a segment port on the middle of the wire e Add a voltage source to the port 1 V 0 e Set the total source power no mismatch to 1 W e Set the frequency to c0 3 We chose lambda as 3 m e The model contains symmetry and 2 planes of symmetry may be added to accelerate the solution A magnetic plane of symmetry is added on the y 0 plane and an electric plane of symmetry on the z 0 plane Requesting calculations The solution requests are e Create a horizontal cut of the far field 0 lt lt 360 0 90 Meshing information Use the standard auto mesh setting with the wire radius set to rho CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 16 2 Dipole and a UTD plate Creating the model The model is identical to the
27. stub 3 times so that there are 3 correctly located copies on each of the other 3 arm ends e Union the parts Requesting calculations Create a single transmission reflection coefficient request leave the phase origin at 0 0 0 The calculation is performed between fmin and fmax using adaptive frequency sampling Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver 29 2 Results Figure 29 2 shows the computed total transmission and reflection coefficients Transmission reflection coefficients Total reflection coefficient Total transmission coefficient 1 0 0 9 0 8 0 6 0 5 0 4 0 3 0 2 0 1 0 0 2 Frequency GHz Total reflection coefficient Total transmission coefficient Figure 29 2 The magnitude of the near field sampled below the surface representing the transmission coefficient of the frequency selective surface July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS 30 1 30 Periodic boundary conditions for array analysis Keywords periodic boundary condition voltage source far field The periodic boundary solution method is used to calculate the far field pattern for a single ele ment in an infinite 2D array of pin f
28. the defined variable L and Depth equal to W Rename this la bel to Patch e Create the substrate by defining a cuboid with the Base corner width depth height defini tion method Set the Base corner to Ls 2 Ws 2 Hs Width Ls Depth Ws Height Hs Rename this label to Substrate e Create the feed pin as a wire between the patch and the bottom of the substrate positioned 8 9 mm x_offset from the edge of the patch The pin should be in the middle of the patch with respect to the width of the patch e Add a segment wire port on the middle of the wire e Add a voltage source on the port 1 V 0 e Union all the elements and label the union antenna e Create a new dielectric called substrate with relative permittivity equal to 2 2 e Set region of the cube to substrate e Set the faces representing the patch and the ground below the substrate to PEC e Set a continuous frequency range from 2 7 GHz to 3 3 GHz Requesting calculations A single plane of magnetic symmetry is used on the y 0 plane The solution requests are e Create a vertical E plane far field request 90 lt 0 lt 90 with p 0 and 2 increments e Create a vertical H plane far field request 90 lt lt 90 with 6 90 and 2 increments e Create a half space far field request 90 lt 0 lt 90 and 90 lt lt 90 and 2 increments Meshing information Use the standard auto mesh setting with the wire segment radius equal t
29. the frequency equal to 30e6 Requesting calculations As all E fields will be normal to the y 0 plane a single plane of electric symmetry is defined on this plane The solution requests are e Select to save only segment currents for post processing in POSTFEKO Meshing information Use the fine or standard auto meshing setting with the wire segment radius equal to 5e 3 The fine meshing simple results in a better representation of the geometry The user is also encour aged to play around with some of the mesh settings on the Advanced tab of the mesh dialog CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 19 2 Results The current induced in a specific segment on the probe is shown versus solution number in Figure 19 2 This is plotted on a currents and charges graph Each solution represents a different plane wave excitation direction starting at 0 0 in steps of 10 to 9 90 for p 0 July 2011 FEKO Examples Guide A MAGNETIC FIELD PROBE 19 3 Wire Currents 5 94 5 92 5 90 5 88 5 86 5 84 5 82 5 80 0 Wire current mA 10 20 30 40 50 60 70 80 90 Plane wave incident angle deg Figure 19 2 The current in an arbitrary segment is plotted as a function of the plane wave excitation incidence angle Note that each segment will result in a slightly different current as a function of the plane wav
30. 0 with 0 Meshing information Use the coarse auto mesh setting We are using the coarse mesh setting in this example to reduce the simulation time The standard mesh setting is recommended in general CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver Note that this is a large simulation and may take quite some time to complete The model that has been created will be referred to as the original model throughout the rest of this example 25 2 Generate equivalent aperture and spherical mode sources using only the horn The model is now simplified by simulating the horn by itself A set of near field points are calculated around the horn and then used as a source for the reflector Creating the model The model is created by saving the previous model with a new name and then making the re quired changes First we delete the dish from the original model and create a model containing only the horn The near and far field information is then calculated and saved to a file The steps for setting up the model containing only the horn are as follows e Open the original model and save it under a new name e Remove the reflector from the model July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 4 Requesting calculations Request a 3D far field with an origin
31. 0 1 Plane wave 3 1 4 1 5 1 PO 16 1 Polygon plate 3 1 Proximity coupling 11 1 Pulse shape 33 1 Radiation pattern 1 1 7 1 14 1 17 1 Radiation pattern point source 24 1 Ray tracing 17 1 RCS Radar cross section 4 1 Real ground 8 1 Resource requirements 21 1 Results Continuous frequency 13 1 Current 7 1 19 1 Far field 1 1 7 1 12 1 14 1 16 1 Gain 8 1 Input Impedance 32 1 Input impedance 1 1 12 1 15 1 RADHAZ 35 1 Radiation pattern 1 1 7 1 9 1 RCS Radar cross section bistatic 3 1 4 1 monostatic 4 1 21 1 Reflection coefficient 11 1 15 1 S parameters 15 1 20 1 22 1 26 1 27 1 S parameters 26 1 27 1 SAR 6 1 Shielded cable 18 1 Shielding 19 1 Shielding calculation 5 1 Skin effect 5 1 Smith chart 11 1 Solution method FEM MoM 6 1 Geometrical optics 17 1 Infinite planar Green s function 8 1 11 1 12 1 Method of Moments 1 1 2 1 5 1 MLFMM 21 1 22 1 MoM GO 16 1 MoM PO 16 1 MoM UTD 16 1 Periodic boundary conditions 29 1 30 1 31 1 Planar multilayer substrate Green s function 10 1 Surface equivalence principle 2 1 4 1 10 1 15 1 Symmetry 11 1 Thin dielectric sheet approximation 3 1 UTD 23 1 Sphere creation 4 1 Surface equivalence principle 2 1 4 1 Thin dielectric sheet approximation 3 1 Time domain 33 1 TIMEFEKO 33 1 Touchstone 27 1 Touchstone file 26 1 transmission line 28 1 Trihedral reflector 21 1 UT
32. 00 MHz Requesting calculations For this example we only wish to view the input impedance of the forked dipole No calculations therefore need be specifically requested Meshing information Use the standard auto mesh setting with the wire segment radius equal to 1 mm CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 13 2 Results In order to view the results for this example we create a Cartesian graph and plot the real and imaginary parts of the input impedance of the voltage source The input impedance is plotted in Figure 13 2 Figure 13 3 shows the same results over a smaller frequency band July 2011 FEKO Examples Guide A FORKED DIPOLE ANTENNA 13 3 Excitation Real Imaginary Admittance mS ar 100 120 140 160 180 200 220 240 260 280 300 Frequency MHz Admittance Forked_Dipole Figure 13 2 Real and imaginary parts of the input admittance of the forked dipole Excitation 25 20 Real Imaginary 15 g 10 8 C 8 E 5 xt 0 5 10 202 203 204 205 206 207 208 Frequency MHz Admittance Forked_Dipole Figure 13 3 Input admittance of the forked dipole around the resonance point July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 1 14 Different ways to feed a horn antenna Keywords
33. 1077e 009 6 52188035675e 003 9 2748292e 001 0 00000000000e 000 4 13341896956e 009 6 52230011210e 003 1 2366439e 000 0 00000000000e 000 3 99393804441e 009 6 52498351875e 003 1 5458049e 000 0 00000000000e 000 5 42911780728e 009 6 52539583297e 003 number x m y m z m 2 5 00000E 01 1 11111E 01 1 11111E 01 Time in 1m JX JY JZ 0 0000000e 000 0 00000000000e 000 1 01039907868e 002 3 60335108452e 003 3 0916097e 001 0 00000000000e 000 1 01040094278e 002 3 60224002199e 003 6 1832194e 001 0 00000000000e 000 1 01040230067e 002 3 60021912950e 003 9 2748292e 001 0 00000000000e 000 1 01040095706e 002 3 60068800501e 003 1 2366439e 000 0 00000000000e 000 1 01040010978e 002 3 60337331960e 003 1 5458049e 000 0 00000000000e 000 1 01040183909e 002 3 60372218859e 003 1 8549658e 000 0 00000000000e 000 1 01040308948e 002 3 60070572711e 003 number x m y m z m 3 5 00000E 01 5 55556E 02 2 22222E 01 Time in 1m JX JY JZ 0 0000000e 000 0 00000000000e 000 1 42589363036e 008 3 60328087662e 003 3 0916097e 001 0 00000000000e 000 1 05535624026e 008 3 60211403945e 003 6 1832194e 001 0 00000000000e 000 9 54716062153e 009 3 60009027207e 003 9 2748292e 001 0 00000000000e 000 1 72541591223e 008 3 60060968405e 003 1 2366439e 000 0 00000000000e 000 9 83456465180e 009 3 60329333536e 003 1 5458049e 000 0 00000000000e 000 1 92479973530e 008 3 60359424366e 003 1 8549658e 000 0 00000000000e 000 5 84461595488e 009 3 60058940940e 003 Figure 33 2 shows the response of the excitation E t in the
34. 14 2 h 3 d 14 2 h e Create a dielectric called ground with relative permittivity of epsr and conductivity equal to sigma e Define an infinite planar multilayer substrate the real ground by setting the Infinite plane ground options to Homogeneous half space e Set the frequency to freq Requesting calculations A single plane of electrical symmetry on the y 0 plane is used in the solution of this problem The solution requests are e Create a vertical far field request above the ground plane 90 lt lt 90 with 0 and 9 0 5 increments Meshing information Use the standard auto meshing option with the wire segment radius equal to lambda 2 5e 3 Note that a warning may be encountered when running the solution This is because losses can not be calculated in an infinitely large medium as is required for the extraction of directivity information This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the Advanced tab of the far field request in the tree CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND 8 3 8 2 Results The radiation pattern is calculated in the H plane of the antenna A simulation without the ground plane is compared with the results fr
35. 1e9 Minimum frequency in operating range f_max 2 3e9 Maximum frequency in operating range epsr_a 10 2 Relative permittivity for the bottom dielectric layer epsr_b 2 54 Relative permittivity for the top dielectric layer lambda_a c0 f_max sqrt epsr_a 100 Wavelength in the bottom dielectric layer lambda_b c0 f_max sqrt epsr_b x 100 Wavelength in top dielectric layer d_a 0 16 Height of bottom dielectric layer d_b 0 16 Height of top dielectric layer patch_1 4 0 Length of the patch antenna July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 2 patch_w 3 0 Width of the patch antenna grnd_l 2 patch_1 Length of substrate layers and ground plane grnd_w 2 5 patch_w Width of substrate layers and ground plane feed_1 lambda_a Length of the microstrip feed line feed_w 0 173 Width of the microstrip feed line stub_l 1 108 Length of the matching stub on the microstrip feed line ap_l 1 0 Length of the aperture 1 ap_w 0 11 Width of the aperture e Set the model units to centimetres e Create a dielectric medium called bottom_layer with relative permittivity of epsr_a and a loss tangent of 0 e Create a dielectric medium called top_layer with relative permittivity of epsr_b and a loss tangent of 0 e Create a ground layer using a plate with its centre at 0 O 0 a width of grnd_w and a depth of g
36. 50 Shunt load resistance d1 d11 dN d N 1 sigmaN len1 1len11 lenN len N 1 tau rad1 rad11 radN rad N 1 tau July 2011 FEKO Examples Guide LOG PERIODIC ANTENNA 28 2 sigmal sigmal1 sigmaN sigma N 1 tau e Create the twelve dipoles using the defined variables Create line geometry number N from dN lenN 2 0 to dN lenN 2 0 e Add a segment port in the centre of every dipole e Define eleven transmission lines to connect the dipoles Each transmission line has a char acteristic impedance of Zline and a length sigmaN Check the Cross input and output ports to ensure correct orientation of the transmission line connections Set the local mesh radius for each segment the defined radN variable e Connect transmission line N between element N 1 and elementN for all the transmis sion lines e Define the shunt load using the admittance definition of a general non radiating network Y parameter Specify the one port admittance matrix manually Y 1 Zload e Connect the general network to Port11 e Set the frequency using the freq variable e Add a voltage source to Port elemento Requesting calculations A far field pattern is requested in the vertical plane p 0 degrees O between 180 and 180 degrees in 2 degree increments Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 01 Note that all wires have local radii set CEM validate After t
37. 760 13 738 Fourier transform of FMM basis funct 56 810 56 794 Calcul of matrix elements 8043 350 8043 498 Calcul of right hand side vector 0 040 0 033 Preconditioning system of linear eqns 162 140 162 159 Solution of the system of linear eqns 666 770 666 720 other 12 360 26 182 total times 8958 900 8972 953 total times in hours 2 489 2 492 Peak memory usage during the whole solution 528 860 MByte The S parameters representing the coupling between the antennas mounted on the helicopter and the reflection coefficients of the antennas as a function of frequency are shown in Figure 22 2 July 2011 FEKO Examples Guide ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT 22 3 S parameter S parameter S31 S parameter S21 S parameter S32 S parameters dB Frequency MHz S parameter S parameter S11 S parameter S22 S parameter S33 S parameters dB 480 182 184 186 188 190 192 194 196 198 200 Frequency MHz Figure 22 2 The input reflection coefficients and coupling between the antennas when mounted on the electrically large helicopter July 2011 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA 23 1 23 Antenna coupling using an ideal receiving antenna Keywords coupling ideal receiving antenna far field data file ffe file helix antenna Yagi Uda antenna electrically large This example involves the calculation of the coupling between a helix a
38. 8 2 1641268e 000 4 11922076322e 007 2 4732878e 000 4 01439061167e 006 2 7824487e 000 3 23064343845e 005 3 0916097e 000 2 14695661081e 004 3 4007707e 000 1 17820902888e 003 VALUES OF THE SCATTERED ELECTRIC FIELD STRENGTH IN THE FAR FIELD in V Factor e j BETA R R not considered THETA PHI 90 00 0 00 Time in lm ETHETA EPHI 0 0000000e 000 50315512865e 005 0 00000000000e 000 3 0916097e 001 87725426236e 005 0 00000000000e 000 6 1832194e 001 24534419130e 005 0 00000000000e 000 9 2748292e 001 55061286138e 005 0 00000000000e 000 1 2366439e 000 02668974577e 005 0 00000000000e 000 1 5458049e 000 54522269379e 005 0 00000000000e 000 1 8549658e 000 40894121712e 004 0 00000000000e 000 2 1641268e 000 3 45656249432e 004 0 00000000000e 000 2 4732878e 000 1 38558672388e 003 0 00000000000e 000 2 7824487e 000 5 76286223583e 003 0 00000000000e 000 3 0916097e 000 1 81197268533e 002 0 00000000000e 000 3 4007707e 000 4 51868883704e 002 0 00000000000e 000 3 7099317e 000 9 04438936427e 002 0 00000000000e 000 4 0190926e 000 1 41781269202e 001 0 00000000000e 000 July 2011 FEKO Examples Guide A TIMEFEKO EXAMPLE 33 4 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 55556E 02 5 55556E 02 Time in 1m JX JY JZ 0 0000000e 000 0 00000000000e 000 5 04976669722e 009 6 52497602709e 003 3 0916097e 001 0 00000000000e 000 3 64334859802e 009 6 52389387315e 003 6 1832194e 001 0 00000000000e 000 5 0546214
39. D 16 1 23 1 Waveguide 14 1 20 1 Waveguide modes 20 1 Windscreen 32 1 Wires 1 1 Y parameters 26 1 Yagi Uda antenna 8 1 9 1 23 1 Z parameters 26 1 1 2
40. D AR oe als 14 5 14 5 Comparison of the results for the different models 14 6 15 A Microstrip filter 15 1 15 1 Microstrip filter on a finite substrate FEM 15 1 15 2 Microstrip filter on a finite substrate SEP 15 4 15 3 Microstrip filter on an infinite planar multilayer substrate 15 5 T54 RESU 664 ess hs GoW Se SOS SHE EOS See PARAS ES SESE EHR SS 15 6 16 Dipole in front of a UTD GO PO plate 16 1 16 1 Dipole in front ofa large plate 0 ek ew ee OA RH AR 16 1 16 2 Dipole and a UTD plate ee canina AAA SR 16 2 16 3 Dipole and a GO plate cis sas rosana yu er a oH 16 3 16 4 Dipole and a PO plate RARA OS SG EE RD 16 4 16 5 Comparative result sk are caninas RS OR ENS i AN e ae 16 4 17 A lens antenna with Geometrical optics GO ray launching 17 1 17 1 oo keismodel so ee we a ie Bw Re SR ie oe ee 17 1 17 MOSES 6 6 6 85 59 AAA SEPALS HO RR BH OS 17 4 July 2011 FEKO Examples Guide CONTENTS 111 18 Calculating field coupling into a shielded cable 18 1 18 1 Dipole and ground oe cese seci ae PO A OE SOS 18 1 18 4 Dll co oe hae ee Ee Ra be See b Lara OH 18 2 19 A magnetic field probe 19 1 19 1 Magnetic field probe 2 2645024 2256 tarada 19 1 TZA Peili A 19 2 20 S parameter coupling in a stepped waveguide section 20 1 20 1 Waveguide step model MoM ic cocoa 20 1 20 2 Waveguide step model FEM os cisco eee be bd ee eee Bh ee OS 20 3 ES IAS 2 00 owe a gin RS e
41. EAL RECEIVING ANTENNA 23 2 freq 1 654e9 The design frequency of the helix lambda cO freq The wavelength in free space n 10 The number of turns for the helix helix_alpha 13 The pitch angle of the helix helix_radius lambda cos helix_alpha pi 180 pi 2 The radius of the helix helix_spacing lambda sin helix_alpha pi 180 The vertical spacing be tween the helix turns plate_radius 0 75 lambda The radius of the ground plate e An ellipse primitive is used to create a circular plate centred around 0 0 0 with a radius of plate_radius This is used to model the finite ground plane of the helix e The helix antenna is created using a Helix primitive with Origin at 0 0 0 Base and End radius of helix_radius Height of nthelix_spacing Number of turns is n e The Helix and Ellipse are unioned to indicate connectivity e A wire port is added on the segment at the start of the Helix e A voltage excitation is applied to the port Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 65e 3 Requesting calculations The far field is requested in the Solution branch of the contents tree e The frequency is set using the freq variable e A full 3D far field calculation request is added The 3D pattern default on the position tab is selected The export of field data to an ASCII file is requested on the Advanced tab This results
42. Edge excitation 15 1 FEM current source 12 1 FEM modal source 12 1 Impressed field distribution 14 1 Microstrip feed 11 1 Pin feed 14 1 Plane wave 3 1 4 1 5 1 19 1 21 1 29 1 31 1 Radiation pattern point source 17 1 24 1 Voltage on an edge 11 1 Voltage source 30 1 Waveguide feed 14 1 20 1 Exposure analysis 6 1 Far field 1 1 7 1 12 1 14 1 16 1 30 1 far field 28 1 Far field data file 23 1 24 1 feed network 27 1 FEM current source 12 1 FEM modal source 12 1 12 3 FEM MoM hybrid 6 1 Finite conductivity 5 1 Finite ground plane 7 1 Geometrical optics 17 1 GO 16 1 Half wavelength dipole 1 1 Helix antenna 23 1 Horn antenna 14 1 24 1 Ideal matching 26 1 Ideal receiving antenna 23 1 24 1 Infinite ground 8 1 12 1 Infinite planar Green s function 8 1 11 1 12 1 Input impedance 1 1 12 1 15 1 Lens antenna 17 1 Lossy metal 2 1 Magnetic field probe 19 1 Materials Dielectric solid 2 1 4 1 17 1 Lossy metal 2 1 5 1 PEG 2 1 Method of Moments 1 1 2 1 5 1 35 1 Microstrip 10 1 11 1 feed line 11 1 Microstrip feed 10 1 Microstrip filter 15 1 MLFMM 21 1 22 1 Monopole antenna 7 1 Near fields 5 1 Non radiating network 26 1 27 1 28 1 Non radiating network 27 1 non radiating network 28 1 Optimisation 9 1 patch 27 1 I 1 Patch antenna 10 1 11 1 PEG 2 1 Pin feed 10 1 14 1 Planar multilayer substrate Green s function 1
43. FEKO Comprehensive Electromagnetic Solutions FEKO Examples Guide Suite 6 1 July 2011 Copyright 1998 2011 EM Software amp Systems S A Pty Ltd 32 Techno Avenue Technopark Stellenbosch 7600 South Africa hh Tel 27 21 880 1880 Fax 27 21 880 1936 SMSS E Mail feko emss co za WWW http www feko info CONTENTS i Contents Introduction 1 1 Dipole example 1 1 LL Dipole corr cid cee oe Re Bee OM So es bee ee eae os 1 1 1a Pe ood Bes oe oy ESS Eee Be SN SEES eS Sede 1 2 2 Dipole in front of a cube 2 1 2L e io ie s sosa eee Chae Seo eed oe oe bee rs 2 1 2 2 Dipole and lossy Metal GUIDE EA ARA a aa 2 2 2 3 Dipole and dielectric cube cs su ro mece dad 2 3 2 4 Comparison of the results cosine dane nk dowd wad ous a eb ae aos 2 3 3 RCS of a thin dielectric sheet 3 1 3 1 Dielectric sheet e A a A 3 1 Da DOI sa ARE ERAS A A AA 3 2 4 RCS and near field of a dielectric sphere 4 1 41l Dielectriesphere 22 koe meraca Se alee Ae SO ee eee p eae SS 4 1 O owe eek ak ee RA OS eS ed Gee eR Oe Eee od 4 2 5 Shielding factor of a sphere with finite conductivity 5 1 5 1 Finite conductivity sphere Method of Moments 5 1 5 2 Finite conductivity sphere Finite Element Method 5 2 Do REWE ad ee a a Be ee ee 5 4 6 Exposure of muscle tissue using MoM FEM hybrid 6 1 6 1 Dipole atid muscle tissue sc kc hw gied ORES OE EE OHS 6 1 Ce a Be A AS eS OR OE RE EO ee 6 2 7 Amonopole anten
44. If changes have been made to the provided models care should be taken to ensure that the number of field points specified for the receiving antenna is consistent with the values stored in the ffe file The pattern file is chosen as the ffe file generated using the free space helix model The origin of the workplane is set to the helix_center named point The U axis direc tion is 1 0 1 to define the orientation of the helix that the pattern represents The Yagi Uda antenna is oriented so that its first side lobe is aimed directly at the helix The radiated power is configured as 100 W by selecting the Total source power no mismatch option on the power settings dialog CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 23 3 The full model The ideal receiving antenna calculates the coupling assuming a matched load to make the results directly comparable the helix antenna in the full model is loaded with the complex conjugate of its input impedance The power loss in the applied load represents the total power received by the antenna This can be found in the out file July 2011 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA 23 5 23 4 Results As coupling parameters cannot be computed directly when using the Ideal receiving antenna the coupling information must be derived fro
45. KO Examples Guide CONTENTS iv 26 2 Dipole matching using a general s parameter network 26 2 20S IM op oe he oe ee Rah ee ey ERE RR AE ea a 26 3 27 Subdividing a model using non radiating networks 27 1 Oo A Feed VON soc ab wer ea ye Gee ee Pe Meee Se eS SSS ees 27 1 27 2 Patch with non radiating feed network 27 2 27 3 Patch with radiating feed network 0 cc eee eee ee eee 27 4 27A ROOMS 66 1 b e 0G EERO SRE RG Oe eK Ee oe Eee are Ee KS 27 4 28 Log periodic antenna 28 1 28 1 Log p rodic dipole aray MMM 28 1 28 2 MEE cesar RARA a E a e a a a PRESSE ESS 28 2 29 Periodic boundary conditions for FSS characterisation 29 1 29 1 Frequency selective surface o ss ia ae OEE GO ee ARA EA OS 29 1 202 MOE cada AR EMS PES ADA ESEE YRS 29 2 30 Periodic boundary conditions for array analysis 30 1 30 1 Pin fed patch Broadside pattern by phase shift definition 30 1 30 2 Pin fed patch Broadside pattern by squint angle definition 30 3 30 3 Pin fed patch Squint pattern by phase shift definition 30 3 30 4 Pin fed patch Squint pattern by squint angle definition 30 3 E e nasi 6 os bse RSS PHS SSE SHE Dees ea eRe oS eS 30 4 31 Scattering width of an infinite cylinder 31 1 31 1 Ininiteeylnder ss se cde eo maana Sew ARE HE eee Hee wee Ew EY 31 1 Ol REWE ong oe eh 6 os obs OS eGR ERG Ee MEER AHR RES ERS 31 2 32 Windscreen antenna on an automobile 32 1 32 1 Re
46. LE IN FRONT OF A CUBE 2 2 Requesting calculations All electric fields will be tangential to the y 0 plane and normal to the z 0 planes An electric plane of symmetry is therefore used for the z 0 plane and a magnetic plane of symmetry for the y 0 plane The solution requests were e A horizontal radiation pattern cut is calculated to show the distortion of the dipole s pattern due to the proximity of the cuboid 0 lt p lt 360 with 0 90 with p 0 where and 0 denotes the angles theta and phi Meshing information e Use the standard auto mesh setting e Wire segment radius 2e 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 2 2 Dipole and lossy metal cube The calculation requests and mesh settings are the same as the previous model Extending the first model The model is extended with the following steps performed sequentially e Create a metallic medium called lossy_metal Set the conductivity of the metal to 1e2 e Set the region inside the cuboid to free space e Setlossy metal properties on the cuboid faces by right clicking in the details tree and setting the Face type to Lossy conducting surface Set the thickness to 0 005 Meshing information e Use the standard auto mesh setting e Wire segment radius 2e 3 July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE 2 3 2
47. MoM model The only change that is required is that the solution method to be used on the plate must be changed This change is made by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Uniform theory of diffraction UTD Now when meshing is done in CADFEKO the plate will not be meshed into triangular elements Also remove corner diffraction effect on the high frequency tab of Solver settings Remove the symmetry definitions for the UTD example the number of elements is so small that it is faster to simulate without symmetry July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A UTD GO PO PLATE 16 3 Requesting calculations No changes are made to the solution requests for the MoM UTD case Meshing information Use the standard auto mesh setting with the wire radius set to rho After changing the solution method on the plate to UTD the model must be remeshed UTD plates are not meshed and a single element will be created for the entire plate CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 16 3 Dipole and a GO plate Creating the model The model is identical to the MoM model note that we are changing the MoM model and not the UTD model The only change that is required is that the solution method
48. NA 24 3 Coupling between antennas Coupling dB Full Model Point Source Approx 1 60 1 61 1 62 163 164 1 65 166 1 67 Frequency GHz 168 169 1 70 Figure 24 2 The comparative results for the full model simulation and the simulation using pre calculated radiation pattern representations of the horn antennas in the model July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 1 25 Horn feeding a large reflector Keywords Waveguide horn reflector PO aperture source spherical mode source equivalent source decouple far field A cylindrical horn is excited with a waveguide port is used to feed a parabolic reflector at 12 5 GHz The reflector is electrically large diameter of 36 wavelengths and well separated from the horn An illustration of the model is shown in figure 25 1 This example illustrates some of the techniques that are available in FEKO to reduce the required resources for electri cally large models Figure 25 1 Illustration of a circular horn and parabolic dish reflector It is very important to understand the problem that is to be solved and the approximations that are being made to reduce the required resources Some of the techniques that can be employed to reduce the required resources are e Use the multilevel fast multipole method MLFMM instead of the method of moments MoM for electrically large models The required memory can be reduced considerably by u
49. NDITIONS FOR ARRAY ANALYSIS 30 5 Gain 20 deg Squint Element phase shift 20 10x10 Array phase shift Element squint angle 10 10x10 Array squint angle Gain dB 10 180 150 120 180 Theta deg Figure 30 3 The far field gain for a single element and for a 10 by 10 element 2D array of pin fed patch elements in the 20 degree squint direction July 2011 FEKO Examples Guide SCATTERING WIDTH OF AN INFINITE CYLINDER 31 1 31 Scattering width of an infinite cylinder Keywords periodic boundary condition plane wave 2D MoM RCS Using a 1 dimensional periodic boundary condition the scattering width of an infinite cylinder defined below is efficiently computed The results are compared with a literature reference C A Balanis Advanced Engineering Electromagnetics Wiley 1989 pp 607 Figure 31 1 A 3D view of the unit cell of the infinite cylinder with the 1 D periodic boundary condition shown 31 1 Infinite cylinder Creating the model The model consists of a cylindrical section of variable radius and height of half a wavelength at the excitation frequency The cylinder is realised by creating a cylinder primitive setting the region to free space and then deleting the upper and lower faces of the cylinder Requesting calculations For this example the scattering width of the cylinder for an incident plane wave normal to the cylinder will be considered A p
50. TCH ANTENNA 10 5 10 4 Comparison of the results for the different models The far field gain patterns for all 3 antenna models at 3 GHz are plotted on the same graph in Figure 10 4 The model with the finite ground is probably the best representation of an antenna that can be built but the simulation time compared to the infinite plane solution is considerably longer We can also see how the edge feed deforms the radiation pattern when compared to the pin fed case Far Field 300 270 Pin feed SEP Pin feed infinite Edge feed infinite 240 180 Figure 10 4 The E plane radiation pattern of the three microstrip patch models July 2011 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED 11 1 11 Proximity coupled patch antenna with microstrip feed Keywords patch antenna aperture coupling microstrip feed proximity coupling voltage on an edge infinite substrate optimisation This example considers a proximity coupled circular patch antenna from 2 8 GHz to 3 2 GHz The magnetic symmetry of the problem is exploited to reduce the number of unknowns and thus increase the calculation speed Note that the model provided with this example includes a basic optimisation The optimisation is set up such the optimum values for the model dimensions may be determined for impedance matching at 3 GHz To run the optimisation the frequency request should be set to a single freq
51. TENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 5 Table 35 2 Definition for electric and magnetic field limits according to NRPB 89 between 0 4 2 0 GHz Field Type Defintion F in GHz Unit Electric field 97 1VF Xy Magnetic field 0 258 VF A July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 6 INIRC88 July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 7 NRPB89 July 2011 FEKO Examples Guide Index ADAPTFEKO 13 1 Adaptive sampling 13 1 Antenna placement 22 1 Application Antenna analysis 1 1 7 1 8 1 10 1 11 1 12 1 13 1 14 1 25 1 26 1 28 1 35 1 Antenna optimisation 9 1 Antenna placement 22 1 Cable analysis 18 1 EMG 5 1 18 1 19 1 Exposure analysis 6 1 Lens antenna 17 1 Microstrip filter analysis 15 1 SAR 6 1 Time domain analysis 33 1 Waveguide analysis 20 1 array 28 1 Cable analysis 18 1 Cable modelling 18 1 CFIE 22 1 Continuous frequency 13 1 Coupling 18 1 22 1 23 1 24 1 Current 7 1 Dielectric losses 6 1 Dielectric resonator antenna DRA 12 1 Dielectric solid 2 1 4 1 Dielectric substrate 10 1 11 1 Dipole 1 1 Forked 13 1 Ideal lumped element matching 26 1 Near a cube 2 1 Near a dielectric sphere 6 1 Near a large metal plate 16 1 dipole 28 1 Edge port 11 1 Electrically large model 21 1 22 1 23 1 24 1 EMG 5 1 18 1 19 1 Excitation
52. a vertical cut far field request YZ plane in 2 steps for the E plane cut e Define a horizontal cut far field request XZ plane in 2 steps for the H plane cut Meshing information Use the coarse auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 14 5 Comparison of the results for the different models The far field gain in dB in the E Plane and H Plane is shown in Figures 14 6 and 14 7 respec tively July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 7 E Plane Cut 0 Waveguide Aperture Figure 14 6 Comparison of the far field gain of the horn antenna with different feeding techniques for the E_Plane far field request H Plane Cut Waveguide I 5 Aperture Figure 14 7 Comparison of the far field gain of the horn antenna with different feeding techniques for the H Plane far field request July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 1 15 A Microstrip filter Keywords microstrip filter FEM SEP input impedance microstrip excitation FEM current source edge excitation reflection coefficient S parameters planar multilayer substrate A simple microstrip notch filter is modelled The filter is solved using several different techniques the surface equivalence principle SEP the finite element met
53. ace wavelength July 2011 FEKO Examples Guide EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID 6 2 e Create the media Create a dielectric named Human_muscle it is available in the media library Create a dielectric named air with a relative permittivity of 1 and dielectric loss tangent of zero e Create a sphere at the origin with a radius set to the defined variable rM Set the label to Sphere1 e Create a sphere at the origin with a radius set to the defined variable rA Set the label to Sphere2 e Subtract Spherel from Sphere2 e Set the region properties of the inside sphere to the dielectric called Human_muscle e Set the region properties of the region between the inside and outside sphere to the dielec tric called air e Create the line a distance of d away from the centre of the sphere Set the Start point as 0 Lambda 4 d and the End point as 0 lambda 4 d e Add wire segment port on the middle of the wire e Add the voltage source on the port 1 V 0 e Set the total source power no mismatch to 1 W e Set a continuous frequency range from f_min to f_max Requesting calculations The solution requests are Create a near field request at 0 0 0 a single request point Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kern
54. akes such an example impractical for explanation purposes This example is large enough to demonstrate the advantage of using the MLFMM Figure 21 1 shows an illustration of the trihedral with a plane wave excitation ZIN Figure 21 1 Plane wave incident on an electrically large trihedral 21 1 Large trihedral Creating the model The steps for setting up the model are as follows e Define the following variables lambda 1 Free space wavelength freq c0 lambda The operating frequency s 3x lambda e Create the first polygonal plate The three corner points are 0 0 0 8 lambda 0 0 and 0 3 lambda 0 e Create the second polygonal plate The three corner points are 0 0 0 0 0 3 lambda and 3 lambda 0 0 e Create the third polygonal plate The three corner points are 0 0 0 0 3 lambda 0 and 0 0 3 lambda e Union the plates July 2011 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS 21 2 e Define a linear plane wave excitation at 0 60 and p 45 e Set the frequency to cO lambda The model is now set up to be solved with the default MoM The model should be set to use the MLFMM solution method with default values All solution method settings including MLFMM are set on the Solver settings dialog under Solution in the main menu Requesting calculations The solution requests are e Create a 180 vertical far field request 0 lt lt 180 with 45 a
55. al 2 8929E 01 deg The phase is relative to the global FEKO phase reference The ideal receiving antenna solution requires fewer resources than the full model If the receiving antenna is moved further away from the transmitting antenna and geometry then the difference in the results will be smaller July 2011 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTENNA 24 1 24 Antenna coupling using a point source and ideal receiving antenna Keywords coupling S parameters radiation pattern point source ideal receiving antenna This example demonstrates the computation of coupling between two horn antennas using the Radiation pattern point source approximation and the Ideal receiving antenna The geometry consists of two horn antennas separated by a distance of 60 wavelengths that point towards one another Exactly half way between the antennas is a metallic plate effectively blocking the line of sight coupling between the antennas Figure 24 1 The full 3D model representation of the problem considered in this example This example consists of 3 models Pyramidal_Horn cfx A model of a horn antenna in free space used to pre compute the far field radiation pattern to be used in the point source radiation pattern and Ideal receiving an tenna parts of the ensuing models Point_Source_Coupling cfx A model that uses the far field radiation pattern of the horn antenna to efficiently extract the coupli
56. anual fz g is approximately 56 MHz so 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 33 1 then yields N 34 NS VAT fnax 33 1 July 2011 FEKO Examples Guide A TIMEFEKO EXAMPLE 33 3 The tim input file Cube tim then contains Timefeko Example tim file Define the Pulse form GAUSS Parameters of the Gaussian pulse xk Time shift Exponent 2 0e 8 3 0e 8 Define the frequency block Gaussian pulse with a 3 0e 8 1 s i e f_3dB 0 187 a 56 2 MHz xk Choose f_max gt 4 f_3dB 224 9 MHz use f_max 250 MHz xk Total time we want to analyse T 40 lightmetres 133 4 ns 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 Qutput the excitation EXCITATION The following is an extract from the output file Cube aus TEMPORAL VARIATION OF EXCITATION NORMALISED TO U_O x y z 0 0 0 0 0 0 Time in 1m 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 1 2366439e 000 1 41120603102e 010 1 5458049e 000 2 44230818918e 009 1 8549658e 000 3 49040118194e 00
57. ar section of automobile 2 1 ee ees 32 1 ee OR cx o Ge ee ew eR Ow HE Ree ee ee ed IR 32 2 33 A TIMEFEKO example 33 1 34 Modelling an aperture coupled patch antenna 34 1 34 1 Aperture coupled patch antenna Full SEP model 34 1 34 2 Aperture coupled patch antenna Aperture triangles in infinite ground plane 34 3 343 ROU AA cee tee SEER EA EDERE ASI OEE EOE EA hA 34 5 35 Antenna radiation hazard RADHAZ safety zones 35 1 A ee cd ene O 35 1 Oo POI cb chee RE Eee Ot RELA ee eee A BO 35 3 July 2011 FEKO Examples Guide CONTENTS vy Index I 1 July 2011 FEKO Examples Guide INTRODUCTION 1 Introduction This Examples guide presents a set of simple examples which demonstrate a selection of the features of the FEKO Suite The examples have been selected to illustrate the features without being unnecessarily complex or requiring excessive run times The input files for the examples can be found in the examples ExampleGuide_models directory under the FEKO installation No results are provided for these examples and in most cases the pre cfm and or opt files have to be generated by opening and re saving the provided project files cfx before the computation of the results can be initiated by running the FEKO preprocessor solver or optimiser FEKO can be used in one of three ways The first and recommended way is to construct the entire model in the CADFEKO user interface The second way is to
58. as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Determine the phase shift by setting the beam angle for Theta 20 and Phi 0 July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS 30 4 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 30 5 Results Figure 30 2 shows the far field gain for the broadside models of a single patch element with the effect of all the other patch elements taken into account and also for the 10 by 10 element array We can see that the gain for the element array is about 10 dB higher than the single element Broadside Gain Element phase shift 20 10x10 Array phase shift Element squint angle 10 10x10 Array squint angle i a fl 3 10 20 30 1860 150 120 Theta deg Figure 30 2 The far field gain for a single element and for a 10 by 10 element 2D array of pin fed patch elements in the broadside direction Figure 30 3 shows the far field gain for the 20 squint angle models of a single patch element with the effect of all the other patch elements taken into account and also for the 10 by 10 element array July 2011 FEKO Examples Guide PERIODIC BOUNDARY CO
59. at 0 O 0 0 lt 0 lt 180 in 0 5 increments 0 lt lt 360 in 5 increments This is the default set of values when 3D pattern is selected on the dialog On the Advanced tab enable the option to Calculate spherical expansion mode coefficients Set the maximum mode index to 20 and ensure that the spherical expansion coefficients are written to an ASCII file This file will be stored with a sph extension Create a spherical near field request with its origin at w_1 0 0 radius of 1 3 w_1 10 lt 0 lt 175 5 lt lt 355 and an increment of 5 for O and q Ensure that the Export fields to ASCII file is checked on the Advanced tab of the Near field request dialog this saves the electric near fields to a efe file and the magnetic near fields to a hfe file Meshing has already been set up and nothing should be changed Save the file and run the solver Once the simulation has completed the model containing on the reflector can be constructed 25 3 Aperture excitation and LE PO reflector The steps for setting up the model containing the reflector and equivalent aperture source are as follows e Open the original model and save it under a new name e Remove the waveguide excitation and port e Remove the horn from the model e Create a new aperture excitation Set the position of the workplane equal to w_1 0 0 Enter the name of the efe and hfe in the Source group box The coordinate system is a spherical coordi
60. at a single frequency of 30 GHz The dielectric lens is illuminated by a radiation pattern point source The radiation pattern is x polarized and positioned at the focal point The E field pattern is described by Ex cos theta 4 where O lt theta lt pi 2 is the polar angle measured from the z axis The pattern data is read from a ffe file with 91 samples and 180 samples in the polar and azimuth angles respectively Far field pattern cuts 0 lt theta lt 180 degree are calculated in the xy plane phi 0 and yz plane phi 90 The angular increment is set to 0 25 to capture the fine angular detail Meshing requirements Generally the mesh size is determined by the smallest wavelength of interest However when using the Geometrical optics GO ray launching approximation the mesh size is determined by the geometry i e the mesh size is chosen to obtain a reasonable faceted representation of the geometry The run time depends on the number of triangles and it is advisable to not over discretise the geometry For this example the arc length of the spherical arc S1 is used as a basis to determine the mesh size It is also possible to use the standard auto meshing but then the settings on the Advanced tab of the mesh dialog will have to be used to ensure better geometrical approximation CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before ru
61. atching network schematic L 42 29 nH 7 oF Figure 26 1 The model of a dipole fed through a non radiating network as well as a schematic for the LC circuit used to match the dipole 26 1 Dipole matching using a SPICE network Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the following variables fmin 1 3e9 The minimum operating frequency h 70 The height of the dipole e Create a 70 mm h line along the z axis with its centre at the origin Label the wire Dipole e Add a wire segment port to the centre of the wire Label the port Port 1 July 2011 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA 26 2 e Set the frequency to be continuous over the frequency from fmin to fmax e Create a general network and rename it MatchingNetwork to correspond to the internal cir file network name e The general network that is used for matching the dipole referenced a file which defines the SPICE circuit of the matching network called Match_circuit cir e Port 1 of this general network is excited using a voltage source excitation The second port is connected to the wire port in the centre of the wire The file Match_circuit cir contains Matching circuit SUBCKT MatchingNetwork ni n2 ci nioO 2 1pF 11 ni n2 43 4n ENDS NWN1 Requesting calculations No solution requests are required in CADFEKO Meshing informa
62. ce intensive for more complex cables The cable analysis solution also allows the use of a database of measured cable properties integrated into FEKO The geometry shown in Figure 18 1 consists of a driven monopole antenna and a section of RG58 shielded cable over an infinite ground plane The RG58 cable is terminated with 50 loads at both ends Figure 18 1 shows the geometry of this model Figure 18 1 RG58 shielded cable illuminated by a monopole above an infinite ground plane 18 1 Dipole and ground Creating the model The steps for setting up the model are as follows e Define some variables fmin 1e6 The minimum operating frequency fmax 35e6 The maximum operating frequency h 0 01 The cable height above ground lambda cO fmax The minimum free space wavelength e Create a line 10 m high with beginning and end point coordinates of 0 0 0 and 0 0 10 July 2011 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE 18 2 e Add a wire segment port to the line Ensure that the port is located close to the origin e Create a cable path definition The cable path for this example consists of the following list of x y x coordinates 0 2 0 01 10 2 0 01 10 5 0 01 7 8 0 01 0 8 0 01 e Create the cable definition RG58 The RG58 cable is one of the predefined coaxial cables that that can simply be selected from the list e Add a voltage sou
63. changed to now use the waveguide feed The line is deleted and the wire port removed The following additional steps are followed e Set a local mesh size of lambda 20 on the back face of the waveguide e A waveguide port is applied to the back face of the guide CADFEKO automatically deter mines the shape of the port rectangular and the the correct orientation and propagation direction It is good practice to visually confirm that these have indeed been correctly chosen as intended by observing the port preview in the 3D view e A waveguide mode excitation is applied to the waveguide port The option to automatically excite the fundamental propagating mode and automatically choose the modes to account for in the solution is used e Symmetry on the x 0 plane may still be used as the excitation is symmetric Meshing information Remesh the model to account for the setting of the local mesh size on the back face of the waveguide CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 14 3 Aperture feed Creating the model Here the modal distribution of the TE mode in a rectangular waveguide is evaluated directly in FEKO as excitation for the horn by means of an impressed field distribution on an aperture also see the FEKO User Manual for information on the aperture field source and the AP card This is of course a much more
64. cific location is safe a graph could also be used as in Figure 35 3 Here it can be seen that the electric field exceeds the maximum limit between 1 024 1 173 GHz July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 4 NRPB 89 Standard 180 150 120 90 60 Electric Field V m 30 0 4 0 6 0 8 1 0 1 2 1 4 1 6 Frequency GHz Electric Field Limit E Field at 0 0316 0 067 0 2 m Figure 35 3 The electric field values at a given location over frequency The scripts The scripts that are used for the calculations are provided Note that they adhere to the standards only for the frequency band over which the model was simulated The resulting values for the INIRC88 and NRPB89 near fields are technically no longer near fields The calculated near field is normalised to the maximum field value of the standard so that a value of 1 corresponds to the maximum threshold a value of 0 8 corresponds to 80 of the maximum threshold and so on This means that the safety zones can be visualised easily and the safety zones can be determined standards The definitions for the standards are given in Tables 35 1 and 35 2 Table 35 1 Definition for electric and magnetic field limits according to INIRC 88 between 0 4 2 0 GHz Field Type Defintion f in MHz Unit Electric field 3 Jf Y Magnetic field 0 008 f A July 2011 FEKO Examples Guide AN
65. complex method than using a readily available waveguide excitation but may be useful in some special cases July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 5 The application of an aperture field source is supported in CADFEKO but the aperture distribution must be defined in an external file This may be done in many ways but for this example the setup is done by using another CAD FEKO model A waveguide section is created and a near field request is placed inside the wave guide Both the electric and magnetic fields are saved in their respective efe and hfe files These files are then used as the input source for the aperture feed horn model For more details on how the fields are calculated see Create_Mode_Distribution_cf cfx To add the aperture excitation to the model create an aperture feed source by clicking on the Aperture field source button and using the following properties e The electric field file is stored as Create_Mode_Distribution_cf efe e The magnetic field file is stored as Create_Mode_Distribution_cf hfe e The width of the aperture is wa e The height of the aperture is wb e The number of points along X U is 10 e The number of points along Y V is 5 e Set the Workplane origin to wa 2 wb 2 wl lambda 4 14 4 FEM modal port Creating the model The steps for setting up the model are as follows e Create a new model e Set the model unit to centimetres e Create th
66. d run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION 20 3 20 2 Waveguide step model FEM The model is almost the same as for the MoM model but the solution method has to be set to FEM and since the FEM modal port allows larger edge lengths on the port faces It is also required to remove the mesh refinement on the port faces Creating the model Make a copy of the MoM model and make perform the following changes e Remove the local mesh refinement on the two ports e Remove S parameter request e Remove the two waveguide ports e Apply FEM modal ports to both faces Port1 and Port2 no specific waveguide excitations are required as only S parameter results are needed e Create a new dielectic medium with the name air and use all the default values for the dielectric e Set the region property of the waveguide to be a dielectric and select air as the dielectric Also ensure that the faces that form the walls of the waveguide are set to PEC e Set the solution method of the region to Finite Element Method FEM e Decouple the FEM and MoM the setting is available on the FEM tab of the Solver settings dialog Requesting calculations The solution requests are e S parameters calculation are requested Fundamental mode for both ports Meshing information Use the standar
67. d auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION 20 4 20 3 Results Save and run the FEKO solver Figure 20 2 shows the computed S parameters with FEKO for both the MoM and the FEM solutions It is clear that the cut off frequency is at about 9 4871 GHz These results agree also very well with available references both measurements and computa tions and agree very well between these two methods since it is difficult to distinguish between them S parameter FEM S11 4 MoMS11 FEMS21 MoM S21 S parameters dB 20 25 9 Frequency GHz Figure 20 2 S parameters for the waveguide step discontinuity July 2011 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS 21 1 21 Using the MLFMM for electrically large models Keywords MLFMM large model Radar cross section trihedral In this example we consider a single plane wave incident from 60 and y 0 on a large trihedral The size of the trihedral 13 51 surface area was chosen such that it can still be solved incore on a PC using 519 MByte of RAM Larger examples show a proportionally larger resource saving by using the MLFMM but the absolute increase in solution time m
68. d element height e Define named points excite_b 0 6 5 1 e Create dielectrics Create a dielectric named air with relative dielectric permittivity of 1 and dielectric loss tangent of 0 Create a dielectric named dome with relative dielectric permittivity of epsr and di electric loss tangent of 0 Create a dielectric named isolator with relative dielectric permittivity of 2 33 and dielectric loss tangent of 0 e Create a new workplane and place its origin at excite_b Set this workplane as the default workplane e Create a cylinder Set respectively the Radius and Height equal to rBig and hBig Modify the label to FeedBase e Create another cylinder Set respectively the Radius and Height equal to r and h hBig Modify the label to FeedPin e Union the two cylinders e Set the region properties of the cylinder FeedPin to the dielectric of type air e Set the region properties of the cylinder FeedBase to the dielectric of type isolator e Create a disk on the x y plane with the radius set equal to rDisk e Create a sphere with a radius of rDomeBig Set the label to OuterDome e Create a sphere with a radius of rDome Set the label to InnerDome e Split both spheres on global x y plane and delete the back parts e Union everything and name the unioned part DRA e Ensure that none of the Edges Faces or Regions have gone suspect in the union operation e Set the region of the internal half sphere to be th
69. del has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 1 2 Results A polar plot of the gain in dB of the requested far field pattern is shown in Figure 1 2 Under the graph display settings open the advanced dialog in the Axes group Set the minimum value of the radial axis to 10 dB and the maximum value to 3 dB Gain 300 270 240 180 Figure 1 2 A polar plot of the requested far field gain dB viewed in POSTFEKO July 2011 FEKO Examples Guide DIPOLE EXAMPLE 1 3 The impedance can be viewed on a source impedance graph but since it is only calculated at a single frequency it may better summarised in the out file The OUT file can be viewed in the POSTFEKO out file viewer or in any other text file viewer An extract is shown below DATA OF THE VOLTAGE SOURCE NO 1 real part imag part magn phase Current in A 1 0027E 02 5 0197E 03 1 1213E 02 26 59 Admitt in A V 1 0027E 02 5 0197E 03 1 1213E 02 26 59 Impedance in Ohm 7 9745E 01 3 9922E 01 8 9180E 01 26 59 Inductance in H 8 4775E 08 Alternately if the calculation is performed over a frequency range the impedance can be plotted against frequency on a source data graph click on Add a source data graph in POSTFEKO July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE 2 1 2 Dipole in front of a cube Keywords dipole PEC metal lossy dielectric A ha
70. e e Translate the metal_plate a distance of 1 5 in the global z direction e The properties of the rectangle face in the details tree are set so that the UTD method will be applied to the face e The Yagi Uda antenna is created using line primitives Create a line with start point 0 0 yagi_1i 2 and end point as 0 0 yagi_1i 2 Set the label to yagi_active e Create a line with start point 0 yagi_d yagi_1d 2 and end point 0 yagi_d yagi_1d 2 Set the label to yagi_director e Create a line with the start point 0 yagi_d yagi_1r 2 and the end point 0 yagi_d yagi_1r 2 Set the label to yagi_ref lector e Create a copy of yagi_director Translate form 0 0 0 to 0 yagi_d e Create a copy of yagi_director Translate form 0 0 0 to 0 2 yagi_d e Union the wires and modify the label to yagi_antenna e Rotate yagi_antenna with 90 15 July 2011 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA 23 4 e Translate yagi_antenna from 0 0 0 to yagi_centre yagi_centre yagi_centre e A wire port is added on the vertex at the centre of the yagi_dipole line e A voltage excitation is applied to the port Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 65e 3 Requesting calculations e The frequency is set using the freq variable e An Ideal receiving antenna is added The number of Theta and Phi points is 37 and 73 respectively
71. e SUBDIVIDING A MODEL USING NON RADIATING NETWORKS 27 3 Creating the model The steps for setting up the model are as follows e Define a new dielectric named RogersDuroid5870 Relative dielectric constant of 2 2 and tan 0 0012 e Add an planar multilayer substrate infinite plane with a height of 2 5 mm and dielectric material RogersDuroid5870 An perfect electric ground should be placed on the bottom of the substrate this is the default e Create the rectangular patch antenna at the origin with a patch width of 39e 3 e Create the slots in the patch where the feed is connected by creating and then subtracting two polygonal plates The length of the rectangular polygon is 6 5e 3 and the width 2 8e 3 e Create the inset microstrip feeds by creating rectangular polygons with length 6 5e 3 and width of 1 4e 3 Union the structures to ensure connectivity e Create two microstrip ports on the two feed terminals e Create a new non radiating general network with three ports that imports network proper ties for the Touchstone file created earlier section 27 1 e Connect the correct microstrip ports to the corresponding network ports e Add a voltage source on the corresponding network port e Set the solution frequency to be from 0 8 2 4e9 to 1 2 2 4e9 Requesting calculations The input impedance at the voltage source is available in POSTFEKO without any requests Add a far field request for a vertical cut Note that no f
72. e Create a Microstrip port on the edge of the feed line furtherest away from the patch element This port is then excited by applying a Voltage source excitation to it e Set the frequency as continuous from 2 8 GHz to 3 2 GHz e Define a magnetic plane of symmetry on the x 0 plane Meshing information Use the standard auto mesh setting but play around with the curvature refinement options on the advanced tab of the mesh dialog While changing these settings around create the mesh and investigate the effects of the different settings Also investigate the difference in the results this illustrates the importance of performing a mesh conversion test for your model Save the model No calculation requests are required for this model since the input impedance is available when a voltage excitation has been defined CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 11 2 Results Figure 11 2 shows the reflection coefficient on the Smith chart July 2011 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED 11 3 Reflection coefficient 0 7 1 1 4 Figure 11 2 Reflection coefficient of the proximity coupled patch July 2011 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND 12 1 12 Dielectric resonator antenna on finite ground Keywords dielectric resonator ante
73. e dielectric The near field inside and outside the sphere as well as the RCS of the sphere is calculated and compared to theoretical results The calculation is done using the surface equivalence principle Figure 4 1 A 3D view of the dielectric sphere and plane wave excitation The CADFEKO preview of the far field request and the symmetry planes are also shown on the image 4 1 Dielectric sphere Creating the model The steps for setting up the model are as follows e Define the following variables lambda 20 Free space wavelength freq c0 lambda Operating frequency R 1 Sphere radius Epsilon 36 Relative permittivity e Create a new dielectric called diel and set its relative permittivity equal to 36 e Create a sphere with a radius of 1 m at the origin July 2011 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE 4 2 e Set the region type of the sphere equal to dielectric and select diel as region medium e Add a plane wave excitation with 0 180 and p 0 e Set the frequency equal to variable freq 14 990 MHz Requesting calculations The geometry in this problem is symmetrical around all 3 principle planes but the excitation is not As the electrical fields of the incident plane wave are purely x directed for the chosen incident angle electrical symmetry may be used in the x 0 plane magnetic symmetry may be used in the y 0 plane but only geometric symmetry may be u
74. e dielectric named dome e Set the region that is left the space around the internal half sphere to be the dielectric named air e For all the regions set the Solution properties to Finite Element Method FEM e Set properties of all the faces visible from the bottom the side of the disk that does not have a sphere to PEC Set all the outside faces of the FeedBase and FeedPin to PEC Set the bottom face of FeedBase to the dielectric isolator July 2011 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND 12 3 e Add a FEM modal port to the dielectric face of FeedBase at the bottom of the antenna e Apply FEM modal excitation to the modal port e Set the frequency to be continuous from 3 GHz to 6 GHz Requesting calculations A single plane of magnetic symmetry on the x 0 plane may be used for this model The solution requests are e Create a vertical far field request in the xz plane 180 lt 0 lt 180 with 0 and 2 steps Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 12 2 DRA fed with a waveguide port Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the same variables as for the FEM MoM model e Define named points excite_b 0 6 5 1 e Cr
75. e excitation July 2011 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION 20 1 20 S parameter coupling in a stepped waveguide section Keywords waveguide S parameter coupling In this example we consider a waveguide transition from Ku to X band by a simple step disconti nuity as shown in Figure 20 1 using two solution methods available in FEKO The model is first simulated using the MoM using waveguide ports and then using the FEM and modal ports The rectangular waveguide dimensions are a 15 8 mm and b 7 9 mm for the Ku band waveguide and a 22 9 mm and b 10 2 mm for the X band waveguide respectively Only the H mode is considered The critical frequency for the chosen H mode in the smaller Ku band waveguide is f 2 9 4871 GHz We want to compute S parameters from this cut off frequency up to 15 GHz using adaptive frequency sampling Figure 20 1 3D view of a waveguide step from Ku to X band 20 1 Waveguide step model MoM Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define some variables fmax 15e9 The maximum frequency lambda c0 fmax 1000 The free space wavelength al 15 8 Width of Ku section a2 22 9 Width of the X section bi 7 9 Height of the Ku section b2 10 2 Height of the X section 11 12 Length of the Ku section July 2011 FEKO Examples Guide S PARAMETER COUPLING
76. e for the pin fed patch on a finite substrate includes a basic optimisation set up The optimisation is defined to determine the value for the pin offset which gives the best impedance match to a 50 Ohm system 10 1 Pin fed SEP model Creating the model In the first example a feed pin is used and the substrate is modelled with a dielectric with specified dimensions The geometry of this model is shown in Figure 10 1 Figure 10 1 A 3D representation of a pin fed microstrip patch antenna on a finite ground The steps for setting up the model are as follows Note that length is defined in the direction of the x axis and width in the direction of the y axis e Set the model unit to millimetres e Define the following variables physical dimensions based on initial rough design epsr 2 2 The relative permittivity of the substrate freq 3e9 The centre frequency lambda c0 freq 1e 3 The wavelength in free space L 31 1807 The length of the patch in the x direction July 2011 FEKO Examples Guide MICROSTRIP PATCH ANTENNA 10 2 W 46 7480 The length of the patch in the y direction x_offset 8 9 The location of the feed Ls 50 The length of the substrate in the x direction Ws 80 The length of the substrate in the y direction Hs 2 87 The height of the substrate e Create the patch by creating a rectangle with the Base centre width depth definition method Set the Width to
77. e last port that will be loaded with a resistance e Add a 120 load on fourth port e Set the solution frequency to be from 0 8 2 4e9 to 1 2 2 4e9 Activate the Specify sampling for exported data files and set the value to 100 Requesting calculations Add an S parameter request for port one to three not the port with the load connected All ports should be active and the reference impedance should be set to 120 2 Meshing information We want to mesh the structure such that the triangle edges are are about as long as the width of the thin microstrip feed triangle edge length of wl CEM validate After the model has been meshed run CEM validate Take note of any warnings notes and errors Please correct error before running the FEKO solution kernel Save the file as patch_feed_bc cfx and run the solver The S parameters can be displayed in POSTEFEKO this should illustrate that the branch coupler is working correctly split power evenly and 90 phase difference between the output ports A Touchstone file containing the calculated S parameters will be located in the project directory named patch_feed_bc s3p 27 2 Patch with non radiating feed network We have simulated and characterised the feed network for the patch antenna in the previous example The result Touchstone file from that simulation is now going to be combined with the patch antenna by using a general non radiating network July 2011 FEKO Examples Guid
78. e reflector and driven element in wavelengths S1 0 3 Spacing between the driven element and the first director in wavelengths 2 0 3 Spacing between the two directors in wavelengths r 0 1e 3 Radius of the elements e Create the active element of the Yagi Uda antenna Set the Start point as 0 O L1 lambda and the End point as 0 0 Li lambda e Add a port on a segment in the centre of the wire e Add a voltage source on the port 1 V 0 e Set the incident power for a 50 transmission line to 25 W e Create the wire for the reflector Set the Start point as SO lambda 0 LO lambda and the End point as SO lambda 0 LO lambda e Create the two directors Set the Start point and End point for Director1 as the following S1 lambda O L2 lambda and Si lambda 0 L2 lambda respectively For Director2 set the Start point and End point as S1 S2 lambda O L3 1ambda and S1 2 lambda 0 L3 lambda respectively e Calculate 21 linearly spaced frequency points from 0 4 GHz to 1 5 GHz Requesting calculations The z 0 plane is an electric plane of symmetry A magnetic plane of symmetry exists in the y 0 plane The solution requests are e Create a 3D Cartesian near field block Start 0 6 0 6 0 6 End 1 2 0 6 0 6 Number of U increments 20 Number of V increments 10 Number of N increments 10 Meshing information Use the standard auto mesh settin
79. e same variables as for the wire model e Create a dielectric labelled air with the default dielectric properties of free space e Create the waveguide section using a cuboid primitive and the Base corner width depth height definition method The Base corneris at wa 2 wb 2 w1 width of wa depth of wb and height of wl in the y direction e Set the region of the of the cuboid to air and delete the face lying on the uv plane e Set the solution method of the region to FEM e Create the horn using the flare primitive with its base centre at the origin using the defini tion method Base centre width depth height top width top depth The bottom width and bottom depth are wa and wb The height top width and top depth are hl ha and hb respectively July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 6 e Set the region of the flare to free space Also delete the face at the origin as well as the face opposite to the face at the origin e Union the waveguide section and the flare section e Set a local mesh size of lambda 20 on the back face of the waveguide e Add a FEM modal port to the back face of the waveguide e Add a FEM modal excitation to the port with the default magnitude and phase e Set the frequency to freq e Set the total source power no mismatch to 5 W Requesting calculations One plane of magnetic symmetry in the x 0 plane may be used The solution requests are e Define
80. e solution requests are e Create a horizontal far field request labelled H_plane 0 lt lt 180 0 90 and 2 incre ments Meshing information Use the standard auto mesh setting with the wire segment radius equal to r Setting up optimisation e An optimisation search is added with the Simplex method and Low accuracy e The following parameters are set LO min 0 15 max 0 35 start 0 2375 L1 min 0 15 max 0 35 start 0 2265 L2 min 0 15 max 0 35 start 0 22 L3 min 0 15 max 0 35 start 0 22 SO min 0 1 max 0 32 start 0 3 S1 min 0 1 max 0 32 start 0 3 S2 min 0 1 max 0 32 start 0 3 e For this example it is required that the reflector element be longer than all the director elements The following constraints are therefore also defined L2 lt L0 July 2011 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA 9 3 L3 lt LO e Two optimisation masks are created The first mask Mask_max defines the upper limit of the required directivity directivity lt 10 between 0 and 30 directivity lt 7 between 62 and 180 e The second Mask Mask _ min defines the lower limit of the required directivity directivity gt 8 between 0 and 30 gain gt 40 between 62 and 180 e Two far field optimisation goals are added based on the H_plane calculation request The dB values 10 x log of the vertically polarised gain at all angles in the requested range
81. e two feed plates added above in the middle to create a feed edge inside the substrate e Union all the geometry Ensure that all faces are still represented by the correct materials and that no entities have gone suspect e Create the edge port connections as illustrated in Figure 15 3 e Ensure that the face properties of the microstrip line the ground below the substrate and sides of the substrate are PEC e Set a local mesh size on the microstrip lines faces of strip_width 0 7 NOTE When the edge source is used together with a finite sized dielectric the edge for the port is not allowed to be on the surface of the dielectric It can either be completely inside the dielectric or completely outside We choose the option of placing the excitation edge inside the dielectric for this example The feed detail is shown below Figure 15 3 A zoomed in 3D view of one of the edge feed excitations July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 5 Requesting calculations The solution requests are e Create an S parameter request with Port1 active and 50 reference impedances Port 2 should be added but not be active Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run the CEM validate 15 3 Microstrip filter on an infinite substrate Planar multilayer Green s function Creating the model Only the shielding box and the microstrip lines are requ
82. e z axis with the base centre at 0 0 w_1 h_1 a radius h_a and a height w_1 Label the cylinder waveguide Create a cone with a base centre 0 0 h_1 a base radius h_b0 a height h_1 and a top radius h_b Label the cone flare Union the two parts and then simplify the resulting union Rename the new part to horn Delete the face on the end of the horn Rotate the horn by 90 so that its centre is along the x axis Set a local mesh size of 1am 15 on the face at the back of the waveguide section Create a waveguide port on the same face Add a waveguide excitation on the waveguide port Excite the fundamental mode use the default settings The horn is now complete The next step is to create the parabolic reflector Create a paraboloid at 0 0 F with radius R and depth F Label the paraboloid reflector Rotate the ref lector with 90 after setting the axis direction to 0 1 0 July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 3 e Set the face properties of the reflector to use Large element PO always illuminated during the solution e Decouple the MoM and LE PO by enabling the Decouple PO and MoM solutions option on the High frequency tab under Solve Run Solver settings e Set a magnetic plane of symmetry at z 0 and an electric plane of symmetry at y 0 e Set the frequency to freq Requesting calculations Create a vertical far field request with an increment of 0 25 90 lt lt 9
83. eate dielectrics Create a dielectric named dome with relative dielectric permittivity of epsr and di electric loss tangent of zero Create a dielectric named isolator with relative dielectric permittivity of 2 33 and dielectric loss tangent of zero e Create a new workplane an place its origin at excite_b Set this workplane as the default workplane July 2011 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND 12 4 e Create a cylinder Set respectively the Radius and Height equal to rBig and hBig Modify the label to FeedBase e Create another cylinder Set respectively the Radius and Height equal to r and h hBig Modify the label to FeedPin e Union the two cylinders e Set the region properties of the cylinder FeedBase to the dielectric of type isolator e Create a disk on the x y plane with the radius set equal to rDisk e Create a sphere with a radius of rDome Set the label to InnerDome e Split the sphere on the global x y plane and delete the back part e Union everything and name the unioned part DRA e Ensure that none of the Edges Faces or Regions have gone suspect in the union operation e Set the region of the half sphere to be the dielectric named dome e Set the region of the cylinder FeedBase to be the dielectric named isolator e Set properties of all the faces visible from the bottom the side of the disk that does not have a sphere to PEC Set all the outside faces of t
84. ed patch elements as well as the approximate very accurate far field pattern for a 10 by 10 element array The far field for the 10 by 10 element array is calculate from the far field pattern for an individual element and does not take edge effects into account Figure 30 1 A 3D view of a single element of the infinite patch array 30 1 Pin fed patch Broadside pattern by phase shift definition Creating the model The steps for setting up the model are as follows e Define the following variables lambda 0 1 The spacing for periodic boundary condition freq c0 lambda Operating frequency of the patch er 2 55 Relative dielectric constant of patch substrate base_width 0 5x lambda Width of the patch substrate 0 5 lambda Length of the patch substrate base_length base_height 0 02 lambda Height of the patch substrate patch_width 0 3x lambda Width of the patch antenna patch_length 0 3 lambda Length of the patch antenna pin_pos patch_length 4 Distance of feed pin from patch centre e Create a dielectric medium named substrate with relative permittivity of er and zero dielectric loss tangent e Create the substrate using the cuboid primitive with the base centre width depth height definition method The side lengths are base_width and base_length and it is base_height thick July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS 30 2 e Crea
85. el 6 2 Results The electric field strength as a function of frequency is illustrated in Figure 6 2 July 2011 FEKO Examples Guide EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID 6 3 Near Field 45 40 35 30 25 Nearfield E Field dBV m 20 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 0 Frequency GHz Figure 6 2 Electric field at the centre of the sphere over frequency July 2011 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE 7 1 7 A monopole antenna on a finite ground plane Keywords monopole finite ground radiation pattern far field current A quarter wave monopole antenna on a finite circular ground plane is constructed and simulated The circular ground has a circumference of three wavelengths and the wire has a radius of 1 x 107 of a wavelength The free space wavelength is chosen as 4 m approximately 74 MHz Figure 7 1 A 3D view of the monopole on a finite circular ground symmetry planes shown 7 1 Monopole on a finite ground Creating the model The steps for setting up the model are as follows e Define the following variables lambda 4 Free space wavelength freq c0 lambda Operating frequency R 3 lambda 2 pi Radius of the ground plane e Create the ground using the ellipse primitive The default material type is PEC Set the radii equal to the defined variable R and the label to Ground e Create a line between
86. el has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS 30 3 30 2 Pin fed patch Broadside pattern by squint angle definition Creating the model Use the same geometry as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Determine the phase shift by setting the beam angle for Theta and Phi to 0 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 30 3 Pin fed patch Squint pattern by phase shift definition Creating the model Use the same geometry as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Manually specify the phase shift in both directions to be uJ 61 56 and u2 0 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 30 4 Pin fed patch Squint pattern by squint angle definition Creating the model Use the same geometry
87. ents with labels Feed1 and Feed2 Feed1 spans from 0 strip_offset strip_width 2 substrate_height to port_offset strip_offset strip_width 2 substrate_height Feed2 spans from gnd_length port_offset strip_offset strip_width 2 substrate_height to gnd_length strip_offset strip_width 2 substrate_height e Union all the geometry and label the union shielded_filter e Set the region properties of the substrate region to substrate and the remaining of the region inside the shielding box to air July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 3 e Set the solution method for the regions to FEM e Ensure that the face properties of the microstrip line the face defining the ground below the substrate as well as all of the outside faces of the shielding box are set to PEC e Select a continuous frequency from fmin to fmax e Under the solver settings decouple the FEM and MoM regions Since the inside of the perfectly shielded box is modelled with the FEM regions there is no energy in the MoM region outside the box meaning that no coupling between the regions is necessary The FEM line port is used to define the excitation points for this model Add FEM line ports to Feedi and Feed2 One of the line ports is shown in Figure 15 2 The ports are labeled Port and Port2 Figure 15 2 A zoomed in 3D view of one of the FEM current source excitations applied to a line port Requesting calculations The sol
88. er the input impedance of a windscreen antenna Windscreen antennas are antennas that are located in or on a windscreen The windscreen can consist of one or more layers and the different layers do not have to be meshed and thus simulation time is greatly reduced when compared to conventional methods Figure 32 1 shows a 3D representation of the car and windscreen being simulated in this example Figure 32 1 3D view of an automobile and a windscreen antennas 32 1 Rear section of automobile The model is created by importing geometry instead of creating it in CADFEKO The required geometry files for the import are available as part of your FEKO installation and is located in the ExampleGuide_models directory Creating the model The steps for setting up the model are as follows e Import the Parasolid geometry for the car car_rear x_b and rename the imported ge ometry to Car_rear Set the scale equal to 1 e Import the Parasolid geometry for the antenna antenna x_b and rename the imported geometry to antenna Set the scale equal to 1 e Union the car and the antenna This ensures that these structures will be connected during meshing e Add a wire port vertex port to the wire that connects the antenna to the car See Fig ure 32 1 for an indication of where this port is located e Add a voltage source to the port that has been created July 2011 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE 32 2 e
89. es are 90 and 180 respectively By default a closed region will be a perfect electric conductor The region type of the Lens part is changed to be dielectric Glass July 2011 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING 17 3 Requesting calculations By default the normal MoM solution method will be used To model the dielectric lens with the geometrical optics approximation we need to specify the solution method for the Lens S1 and Lens S2 faces From the Solution tab of the Face properties dialogue select the Geometrical optics GO ray launching special solution method In general to check which special solution methods are being applied the user can use the View by solution parameters from the View menu The geometrical optics approximation has two user options that affect the solution e Maximum no of ray interactions default three e Ray launching settings default Automatic The present implementation does not take into account the local curvature at the interaction point This assumption approximation could fail when using a large number of ray interactions and where the local curvature of the geometry can t be neglected These settings can also be changed on the Solver settings High frequency dialog Unselect the automatic setting for the angular increment Set the dielectric GO ray launching settings for theta and phi to 1 5 respectively The analysis is requested
90. espo Valero Katarina Blagovic Frederic Bongard and Juan R Mosig Integral Equation Analysis of 3 D Metallic Objects Arranged in 2 D Lattices Using the Ewald Transformation IEEE Trans Microwave Theory and Techniques vol 54 no 10 pp 3688 3697 Note that the model supplied with this example includes an optimisation set up to determine the best set of geometrical parameters to maximise reflection and minimise transmission at 8 GHz To perform the optimisation the frequency request should be set to a single frequency equal to 8GHz Figure 29 1 A 3D view of the FSS structure The Jerusalem cross unit cell structure is shown with the plane wave excitation and periodic boundary condition 29 1 Frequency selective surface Creating the model The steps for setting up the model are as follows e Define the following variables d 15 2 The spacing for periodic boundary condition L 13 3 Arm length end_w 5 7 Arm width rSmall 0 1 Width of stub extension fmin 2e9 The minimum frequency fmax 12e9 The maximum frequency July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR FSS CHARACTERISATION 29 2 e Create a polygon in the shape of the central cross Alternatively a polygon representation of one of the arms may be created and this may be copied and rotated to create the other 3 arms e Create a polygon for a stub on the end of one arm of the cross e Copy and rotate the
91. etai e Set the frequency to freq Requesting calculations The geometry of the problem is symmetrical around the x 0 and y 0 planes but the excitation has no symmetry 2 planes of geometric symmetry are therefore specified in the model settings The solution requests are e Create a vertical far field request 180 lt 0 lt 180 with 0 Meshing information e Use the standard auto mesh setting e Wire segment radius 2e 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 3 2 Results The bistatic RCS of the dielectric sheet at 100 MHz as a function of the angle 0 in the plane p O is shown in Figure 3 2 vertical axis on a log scale July 2011 FEKO Examples Guide RCS OF A THIN DIELECTRIC SHEET 3 3 Radar cross section 0 01 0 001 0 0001 RCS m 0 00001 0 000001 180 150 120 90 60 30 0 30 60 90 120 150 180 Theta deg Figure 3 2 Bistatic RCS of a thin dielectric sheet July 2011 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE 4 1 4 RCS and near field of a dielectric sphere Keywords dielectric plane wave sphere bistatic RCS monostatic RCS A lossless dielectric sphere with radius of 1 m and relative permittivity equal to 36 is excited by means of an incident plane wave The wavelength of the incident field is 20 m in free space 3 33 m in th
92. g and also merge identical variables and media e Delete the S parameter request e Delete port2 and port3 Keep port1 and port4 e Union the two structures e Set all suspect faces and edges not suspect Requesting calculations The meshing setting has already been added Simply create the mesh with the settings as they are on the dialog standard auto mesh setting Save the file and run the solver 27 4 Results The difference in solution time and required main memory is tabled in Table 27 1 We see that the solution time is almost halved by subdividing the problem Since the field coupling between the feed and the patch can not be taken into account when substituting the feed with a general non radiating network the results are slightly different as can be seen in figure 27 2 The great advantage really becomes clear when the user has to design the antenna and cannot or does not want to change the feed network This allows fast simulations during antenna de velopment Verification can then be done after development that includes a full 3D field solution including the patch and the feed network July 2011 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS 27 5 Table 27 1 Comparison of resources for the simulations per frequency Model RAM Time Total Time Full model 8 6 Mb 311 311 Network only 2 6 Mb 68 Patch with general network 1 6 Mb 49 117 Excita
93. g with the wire segment radius equal to r July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 3 35 2 POSTFEKO A session containing the following instructions is provided radiation_zones pfs The ses sion contains the results from the antenna simulation and three script results INIRC88 This script results in a near field result that incorporates the calculated near fields and the INIRC 88 safety standards for occupational limits NRPB89 This script results in a near field result that incorporates the calculated near fields and the NRPB 89 safety standards standards This is a custom dataset that contains both of the standards used here The result can be plotted on a 2D graph and shows the maximum field limits for both magnetic and electric fields over the calculated frequency band Figure 35 2 shows these results for both the magnetic and electric field limits Standard Magnetic Electric Field Limits Magnetic INIRC88 Magnetic NRPB89 Electric INIRC88 Electric NRPB89 350 300 250 200 Magnetic Electric Field Limits mA m V m Frequency GHz Figure 35 2 The definition of the standards used in the calculated band The 3D representation for the safety zones can be depicted in a variety of formats In Figure 35 1 the safety zones are indicated at 0 95 GHz Similar zones can be drawn for any value in the calculated frequency band To ensure that a spe
94. h the MLFMM with those obtained with the MoM July 2011 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS 21 3 Radar cross section Q O MoM e MLFMM RCS dBm2 N N o al o a o al 0 30 60 90 120 150 180 Theta deg Figure 21 2 Bistatic RCS of a trihedral Comparison of the MLFMM and MoM results July 2011 FEKO Examples Guide ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT 22 1 22 Antenna coupling on an electrically large object Keywords electrically large MLFMM CFIE coupling antenna placement S parameters A Rooivalk helicopter mock up model with 3 monopole antennas located near the front mid dle and back of the model respectively S parameters coupling are computed between the 3 antennas over a frequency range Figure 22 1 3D view of the helicopter NOTE Due to calculations over a frequency range as well as the electrical size of the problem several hours of computation time is required 22 1 Helicopter This example consists of complicated geometry and the model for this geometry is provided with the FEKO installation The important features of this model are briefly presented e The model is solved with the MLFMM this is set under Solver settings e The Combined Field Integral Equation CFIE is used This is set on the face properties Here all the unit normals must point outward Requesting calculations The solution requests were e The S
95. he FeedBase and FeedPin to PEC Set the bottom face of FeedBase to the dielectric isolator e Add a waveguide port to the dielectric face of FeedBase at the bottom of the antenna e Apply waveguide excitation to the waveguide port e Set the frequency to be continuous from 3 GHz to 6 GHz Requesting calculations A single plane of magnetic symmetry on the x 0 plane may be used for this model The solution requests are e Create a vertical far field request in the xz plane 180 lt 0 lt 180 with 0 and 2 steps Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND 12 5 12 3 Results The calculated S for 3 GHz to 6 GHz is shown in Figure 12 2 A radiation pattern at 3 6 GHz is shown in Figure 12 3 Results are shown for both modelling methods Excitation S11 dB FEM Modal port _ Waveguide port 3 0 3 5 4 0 4 5 5 0 5 5 6 0 Frequency GHz Figure 12 2 Input reflection coefficient for the DRA antenna Gain dB 0 300 270 240 FEM Modal port Waveguide port Figure 12 3 Vertical XZ plane gain in dB at 3 6 GHz July 2011 FEKO Examples Guide A FORKED DIPOLE ANTENNA 13 1 13 A Forked Dipole antenna Ke
96. he model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver 28 2 Results The vertical gain in dB at 49 29 MHz and the input impedance over the operating band of the LPDA are shown in Figure 28 2 and Figure 28 3 respectively Note to reproduce the result showing the impedance over the band the simulation frequency settings for the model need to be adjusted July 2011 FEKO Examples Guide LOG PERIODIC ANTENNA 28 3 Gain 180 Figure 28 2 The vertical gain of a LPDA antenna at 46 29 MHz Real Imaginary Impedance Ohm 35 40 45 50 55 60 Frequency MHz Figure 28 3 The input impedance real and imaginary of the LPDA antenna over the operating band July 2011 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR FSS CHARACTERISATION 29 1 29 Periodic boundary conditions for FSS characterisation Keywords periodic boundary condition plane wave frequency selective surface near field optimisation A Jerusalem cross FSS frequency selective surface structure modelled using infinite periodic boundary conditions is excited with an incident plane wave as shown in Figure 29 1 The frequency dependant transmission and reflection coefficients of the surface are computed and considered These results may be compared to those reported in the literature Ivica Stevanovic Pedro Cr
97. hod FEM and on an infinite sub strate using a planar multilayer substrate modelled with Green s functions The reference for this example may be found in G V Eleftheriades and J R Mosig On the Network Characterization of Planar Passive Circuits Using the Method of Moments IEEE Trans MTT vol 44 no 3 March 1996 pp 438 445 Figs 7 and 9 The geometry of the finite substrate model is shown in Figure 15 1 Figure 15 1 A 3D view of the simple microstrip filter model in CADFEKO A cutplane is included so that the microstrip lines of the filter inside the shielding box are visible 15 1 Microstrip filter on a finite substrate FEM Creating the model The substrate and shielding box are made using cuboid primitives The microstrip line is built using a cuboid primitive and removing the undesired faces The stub is added by sweeping a line that forms a leading edge of the stub The steps for setting up the model are as follows e Set the model unit to millimetres e Create the following variables fmax 4e9 Maximum frequency fmin 1 5e9 Minimum frequency epsr 2 33 Substrate relative permittivity shielding_height 11 4 Height of the shielding box July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 2 substrate_height 1 57 Substrate height gnd_length 92 Length and width of substrate port_offset 0 5 Inset of the feed point strip_width 4 6 Width of the
98. ield can exist below an infinite perfect electrically conducting plane The far field request should only be for field points above the infinite plane 85 lt 0 lt 85 with p 0 and 5 increments Meshing information The faces of the two microstrip feeds have to be meshed finer than the patch The required mesh size is determined by the size of the geometry Set the local mesh size on these faces to wl The global mesh is set on the Create mesh dialog and should use the standard auto mesh setting Save the file as patch_network_feed cfx and run the solver The input impedance and far field results can be viewed in POSTFEKO July 2011 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS 27 4 27 3 Patch with radiating feed network The advantage of being able to model the feed as a non radiating general network can only be seen when comparing the results and the required resources with the full 3D simulation Creating the model The patch antenna model patch_network_feed cfx will be used as base model and the branch coupler model patch_feed_bc cfx imported The complete simulation is then per formed The steps for setting up the model are as follows e Open the file patch_network_feed cfx and save it as patch_feed_full cfx e Delete the voltage excitation remove the general network connections and then delete the general network and all the ports e Import the file patch_feed_bc cfx Import everythin
99. ieve a specific gain pattern maximise the forward gain and minimise back lobes as W A Figure 8 1 A 3D view of the Yagi Uda antenna suspended over a real ground symmetry plane not shown 8 1 Antenna and ground plane Creating the model The steps for setting up the model are as follows e Define the following variables freq 400e6 Operating frequency lambda c0 freq The wavelength in free space at the operating frequency lr 0 477 lambda Length of the reflector li 0 451 1lambda Length of the active element ld 0 442 1lambda Length of the directors d 0 25 lambda Spacing between elements h 3 Height of the antenna above ground epsr 10 Relative permittivity of the ground sigma 1le 3 Ground conductivity e Create the active element with Start point as 0 1i 2 h and the End point as 0 11 2 h Set the label as Active element July 2011 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND 8 2 e Add a port on a segment in the centre of the wire e Add a voltage source on the port 1 V 0 e Create the wire for the reflector Set the Start point as d 1r 2 h and the End point as d 1r 2 h Set the label as reflector e Create the three wires for the directors Director Start point End point Director1 d 1d 2 h d 1d 2 h Director2 2 d 1d 2 h 2 d 1d 2 h Director3 3 d
100. in an ffe file being written to disk for later use After running the FEKO solution in addition to the standard FEKO output the computed far field data is stored in the ffe file This is used in the following model in this example July 2011 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA 23 3 23 2 Using the helix antenna far field pattern In the Antenna_Coupling_ Receiving _Antenna cfx model the Yagi Uda antenna and the large conducting sheet are added The receiving antenna is correctly positioned and rotated relative to these by specifying a local coordinate system Creating the model The steps for setting up the model are as follows e Define variables freq 1 654e9 Design frequency of the helix lambda c0 freq The spacing between yagi elements yagi_ld lambda 0 442 The length of director element lambda 0 451 The length of active element lambda 0 477 The length of reflector element yagi_rho lambda 0 0025 The radius of yagi elements yagi_li yagi_lr e Define named points helix centre 1 5 2 3 4 1 5 as the helix antenna location yagi centre 1 5 2 3 4 1 5 as the Yagi Uda antenna location e The rectangle primitive is used to create the plate Firstly a new workplane is created on the yz plane A rectangle with width 3 and depth 6 is created by using the definition method Base centre width depth Set the label to metal_plat
101. ipting Safety standards differ from country to country industry to industry and may change over time This example illustrates how POSTFEKO scripts can be used to fully customise the calculation of such results A yagi antenna is simulated with a full 3D near field cube for the immediate surroundings Using math scripts in POSTFEKO the radiation standards are used to identify the safety zones for the antenna z Figure 35 1 The 3D safety zones for 80 and maximum i e 100 exposure levels according to the INIRC 88 standard 35 1 CADFEKO The antenna in a given environment gives rise to electric and magnetic fields These fields will differ in strength and shape depending on the input power antenna design and surrounding environment Creating the model The steps for setting up the model are as follows e Define the following variables physical dimensions based on initial rough design freq 1e9 The operating frequency lambda cO0 freq The wavelength in free space at the operating frequency LO 0 2375 Length of one arm of the reflector element in wavelengths L1 0 2265 Length of one arm of the driven element in wavelengths L2 0 2230 Length of one arm of the first director in wavelengths July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 2 L3 0 2230 Length of one arm of the second director in wavelengths SO 0 3 Spacing between th
102. ired The lower face of the shielding box and the substrate are removed and modelled using a planar multilayer substrate The changes that must be made to the FEM model are given below e Delete the S parameter request and both of the line ports including the line segment ge ometry used to define the port locations e Set the region properties of the two regions back to MoM MLEMM with surface equivalence principle SEP default Also set the air region back to Free space e Delete the bottom face of the shielding box as well as the bottom part of the microstrip line The box should now be open from below and all faces should be PEC e Delete the face surrounding the microstrip line and stub The only horizontal faces remain ing are then the top of the microstrip line and the top of the shielding box e Create a planar multilayer substrate Add a layer of type substrate that has a thickness of substrate_height The top of the substrate is at z substrate_height Add a PEC ground plane to the bottom of the substrate layer e As there is an infinite ground plane in this model the microstrip port may be used to define the excitation Microstrip ports are attached to each of the port edges These ports are then referenced in the S parameter solution request The polarisation of the ports should be chosen such that the positive terminals indicated by a red cylinder in the 3D view are on the microstrip e Set a local mesh size on the micros
103. lane wave excitation for 9 90 and p 0 is used The 1D periodic boundary condition is defined along the axis of the cylinder so that the unit cell touches the edges of the periodic region A near field request is used to determine the direction dependant scattered field from which the scattering width is derived The calculation is performed at a frequency of 299 8 MHz wavelength of 1m July 2011 FEKO Examples Guide SCATTERING WIDTH OF AN INFINITE CYLINDER 31 2 Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct error before running the FEKO solution kernel 31 2 Results Figure 31 2 shows the computed RCS as a function of incident angle for two different cylin der radii The results agree well with the literature reference Scattering width o Radius 0 1m Radius 0 6m Nearfield E Field V m 0 30 60 90 120 150 180 210 240 270 300 330 360 Phi deg Figure 31 2 The RCS of an infinite cylinder with two different radii modelled using a 1 dimensional infinite periodic boundary condition The scattering width of a near field at a radial distance of 500 m is considered July 2011 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE 32 1 32 Windscreen antenna on an automobile Keywords windscreen input impedance antenna In this example we consid
104. lectric lens with a spherical surface S and elliptical surface S is constructed The lens is illuminated by a radiation pattern point source based on a pre computed cos x radiation pattern and the far field pattern is computed The lens structure is modelled using the Geometrical Optics ray launching method The results are compared to the MoM FEM result The model is shown in Figure 17 1 The notes below do not provide a step by step approach to re construct the model but are mainly intended to aid in an understanding of the ideas used during the model construction It is suggested that the model provided with this example be opened and viewed while working through this text Figure 17 1 The 3D view of the dielectric GO lens model with a point excitation symmetry planes shown Creating the model The model is constructed in mm It is assumed that the focal point of the lens is positioned at the global origin A lens shape consisting of a spherical surface and an elliptical surface is assumed The spherical surface is centred at the focal point The dielectric lens model has the following user defined parameters July 2011 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING 17 2 e freq 30e9 The operating frequency e lambda_0 c0 freq Free space wavelength e D lambda_0 10 Diameter of cylinder eF 1 5 D Focal length e epsr 6 The relative permittivity
105. lements with zero offset Accuracy is improved when elements close to the windscreen are also considered active windscreen elements TIP It may help to hide the windscreen while selecting these faces e Set the frequency to be continuous from 100 MHz to 110 MHz e We are interested in the input impedance of the antenna and thus no solution requests are required The input impedance is automatically calculated for voltage sources Meshing information Use the coarse auto mesh setting with wire segment radius equal to 0 0005 CEM validate After the model has been meshed run CEM validate and ensure that no errors or wanings are reported The Solve Run View by solution parameters dialog can be used to see and ensure that the correct elements have been selected as reference and active elements Figure 32 2 shows the items that should be active elements 32 2 Results Save and run the FEKO solver Figure 32 3 shows the computed input impedance as a function of frequency from 100 MHz to 110 MHz It is recommended to use MLFMM for simulation at higher frequencies 500 MHz or more July 2011 FEKO Examples Guide 32 3 WINDSCREEN ANTENNA ON AN AUTOMOBILE Figure 32 2 3D view of an automobile and a windscreen antennas Excitation Imaginary Real o e 7 7 j T E if i 1 j j i i I l l j j j O Ree EEE ee Dee IPEE O Os ee Ul if I
106. lf wavelength dipole is placed three quarters of a wavelength away from a cube The radi ation pattern is calculated and the effect of the nearby cube on the radiation pattern is demon strated Three different cubes are modelled in this example The first cube is PEC perfect electrically conducting the second is a metal cube that has a finite conductivity and the third cube is made as a solid dielectric material The second and third models are an extension of the first model The examples should be set up sequentially Figure 2 1 A 3D view of the dipole with a metallic cube model symmetry planes shown 2 1 Dipole and PEC cube Creating the model The steps for setting up the model are as follows e Define the following variables lambda 4 Free space wavelength freq c0 lambda Operating frequency h lambda 2 Length of the dipole e Create a cube The cuboid is created with the Base corner width depth height definition method The base corner is at 0 lLambda 4 lambda 4 and with the width depth and height set equal to lambda 2 By default the cube will be PEC e Create a line between the points 0 0 h 2 and 0 0 h 2 Place the wire 3 4 lambda away from the cube by translating it by 3 4 lambda in the negative x direction e Add a wire port at the centre of the line e Add a voltage source to the port e Set the frequency to the defined variable freq July 2011 FEKO Examples Guide DIPO
107. ll 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 POSTFEKO if 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 Define the points DP Pi a 2 0 0 DP P2 a 2 a 2 0 DP P3 a 2 a 2 a 2 DP P4 a 2 0 a 2 DP P5 0 0 a 2 DP P6 0 a 2 a 2 DP P7 0 a 2 0 Create one eigth of the cube use label 1 for the front plate and label 0 for the rest LA 1 BP P1 PZPS TEPA LA 0 BP PS P4 PE P6 BP P2 P3 P6 PT Mirror around to coordinate planes so that label for front plate remains 1 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 SY 1 1 0 0 1 CB 2 0 SY 1 0 3 2 End of the geometry EG 1 0 1 0 0 Set the frequency FR 1 0 freq Excitation by means of an incident plane wave AO 0 1 1 1 0 90 0 Surface current density output for surface with label 1 os 4 1 1 Calculate the far field only in the direction of incidence lg End EN For this example we have chosen a Gaussian pulse excitation with a 3 x 10 As discussed in the FEKO User M
108. m eR Oe ER el eee ee ew ee ee 20 4 21 Using the MLFMM for electrically large models 21 1 2 Large Hes eoa he ed Rie oe oh HOSA D A 21 1 aka ee oe See Oe ee IS Ee ee pee ESE eS 21 2 22 Antenna coupling on an electrically large object 22 1 POA ENON ki oe dR eRE SHEA ERE EDY OHSS EER ORES EES 22 1 aAa II eh le ER ee AD Se 22 2 23 Antenna coupling using an ideal receiving antenna 23 1 23 1 The helixantenna in fre spate a he PS HEE ROK SO PER ERS 23 1 23 2 Using the helix antenna far field pattern lt 4 4 dace a ee ee eS EO 23 3 238 9 TICA OL eh ace oe oe eh eS AA a hw ea eee ee eee 23 4 O A ode RSE EMEA HES ES EYEE OO SDDS ES GOERS 23 5 24 Using a point source and ideal receiving antenna 24 1 24 1 The horn antenna in free space oras oe be A a 24 1 24 2 Using the computed horn radiation pattern in a coupling calculation 24 2 24 3 The reference model i Se oe See eee ee ee ee SEE Sere 24 2 A A 24 2 25 Horn feeding a large reflector 25 1 25 1 MoM horn and LE PO reflector 4 4 54020 04s000us dae eeeas 25 1 25 2 Generate equivalent aperture and spherical mode sources using only the horn 25 3 25 3 Aperture excitation and LE PO renee esas en ee ew Se ew was 25 4 25 4 Spherical excitation and LE PO reflector escocia a eee SE 25 4 25 5 Comparative SUS os SA he So a A we eS 25 5 26 Using a non radiating network to match a dipole antenna 26 1 26 1 Dipole matching using a SPICE network 66 50s 04 eae eee eos 26 1 July 2011 FE
109. m received power information In POSTFEKO the received power may be plotted on a graph or found in the text based output of the out file On the same graph the power lost in the matching load from the full model may be plotted As we have chosen the radiated power to be exactly 100 W for all cases the coupling can be calculated from Received power Coupling gg 10 log10 The comparative results are shown in Table 23 1 Received power mW Coupling dB Runtime s Full model 3 738 44 27 143 Ideal receiving antenna 4 374 43 59 0 468 Table 23 1 Coupling results with 100 W transmitted power The power loss computed in the full model is shown in this extract from the output file named Antenna_Coupling_Full out POWER LOSS METAL in Watt in the segments in the Label skineffect conc load distr load coating triangles helix_antennas Wire3 0 0000E 00 3 7386E 03 0 0000E 00 0 0000E 00 0 0000E 00 total 0 0000E 00 3 7386E 03 0 0000E 00 0 0000E 00 0 0000E 00 Total loss in the segments 3 7386E 03 W Total loss in the triangles 0 0000E 00 W Loss metal total 3 7386E 03 W Both the power lost in the conjugate load from the full model and the power received by the ideal receiving antenna can be plotted in POSTFEKO Ideal receiving antenna with name ReceivingAntennal RECEIVED POWER IDEAL RECEIVING ANTENNA Received power ideal match assumed 4 3748E 03 W Relative phase of received sign
110. me of the edges see description above CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 34 2 Aperture coupled patch antenna Aperture triangles in infinite ground plane This model uses the planar multilayer substrate to replace the dielectric substrate of the first model Aperture triangles are used to model the aperture in the PEC ground plane between the layers This approach provides an equivalent model that requires far less resources than the full SEP model July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 4 Creating the model The steps for setting up the model are as follows e Define the same variables as for the full SEP model e Follow the same creation steps as for the first model up to the point where all of the PEC parts have been created that are required for the model e Create a planar multilayer substrate Add two layers Layer 1 should have a bottom ground plane a height of d_b and the medium should be set to top_layer Layer 2 should not have any ground plane a height of d_a and the medium should be set to bottom_layer The z value at the top of layer 1 should be d_b e Union all of the geometry parts e Set the solution method of the face representing the aperture to Planar Green s function aperture e In order to obtain accurate results whilst minimising
111. microstrip sections strip_offset 23 Offset of the microstrip from the ground edge stub_length 18 4 Length of the stub stub_offset 41 4 Inset length from the ground edge to the stub e Create a dielectric medium named air with the default properties of a vacuum e Create a dielectric medium named substrate with relative permittivity of epsr and zero dielectric loss tangent e Create the substrate using the cuboid primitive with the Base corner at 0 0 0 The side lengths are gnd_length and has a height of substrate_height Label the cuboid substrate e Create the shielding box using the cuboid primitive with the Base corner at 0 0 0 The side lengths are gnd_length and it is shielding_height high and label the cuboid shielding box e Create a cuboid for the microstrip at Base corner port_offset strip_offset 0 The cuboid width is set to gnd_length port_offset 2 a depth of strip_width and with a height of substrate_height Label the cuboid mircostrip e Delete all four vertical faces of mircostrip cube created above e To illustrate the sweep tool the stub will be created by sweeping a line segment Create a line segment that spans from stub_offset strip_offset strip_width substrate_height to stub_offset strip_width strip_offset strip_width substrate_height Select the line and sweep it from 0 0 0 to 0 stub_length 0 to generate a rect angular patch e Create the following line segm
112. mple files under a new name Since the dipole is less than a wavelength away from the plate the standard auto meshing will not work Mesh the plate with a triangle edge length of a 4 The comparison between memory requirements and runtimes are shown in Table 16 1 The method of moments MoM is used as reference and all other methods are compared using a memory and runtime factor Requirements for the MoM solution was 18 s and 68 473 MB July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A UTD GO PO PLATE 16 5 Far Field MoM MoM UTD MoM GO MoM PO MoM LEPO Figure 16 2 A polar plot of the total far field gain dB computed in the horizontal plane using the MoM GO MoM UTD MoM PO and MoM LE PO methods compared to the full MoM ref erence solution Solution method Memory of MoM Runtime of MoM Physical Optics MoM PO 2 0 53 Large Element PO MoM LE PO 0 22 Uniform Theory of Diffraction MoM UTD 0 045 Geometric Optics MoM GO 1 6 Table 16 1 Comparison of memory and runtime requirements for a model using different hybrid solution methods July 2011 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING 17 1 17 Analysing a lens antenna using the Geometrical optics GO ray launching Keywords Geometrical optics lens antenna dielectric radiation pattern radiation pattern point source 17 1 Creating the lens model A die
113. na on a finite ground plane 7 1 7 1 Monopole on a finite ground 6 e 5se6ecee nde bavi deedesd 7 1 Fe IM a Re ee ae a o ES eee ee AA 7 2 8 Yagi Uda antenna above a real ground 8 1 8 1 Antennaand ground plane AAA AAA 8 1 Ba Heili Terse A A A A PES 8 3 9 Pattern optimisation of a Yagi Uda antenna 9 1 Ei SOR scc ase BAe ape daara e a AA ARIAS 9 1 a REUE 6 oh E AR AS 9 3 July 2011 FEKO Examples Guide CONTENTS ii 10 Microstrip patch antenna 10 1 10 1 Pin tfed SEP model sc cs dhe Se a oe BS ES A pyt aka 10 1 10 2 Pin fed planar multilayer substrate omic ee eee ae eee ss 10 3 10 3 Edge fed planar multilayer substrate anaana saaa aea 10 4 10 4 Comparison of the results for the different models 10 5 11 Proximity coupled patch antenna with microstrip feed 11 1 ILL Circula AI 11 1 Tha Peili AS oe ES ES OO EGER EERE a 11 2 12 Dielectric resonator antenna on finite ground 12 1 12 1 DRA fed with a FEM modal port 2 ciu vec ena w ec daaeseeea eas 12 1 12 2 DRA fed witha waveguide port o ci A PRS EEE EE EHS 12 3 E eean a a eee oe ee T owe a hoe bee eee a bbe ee ed 12 5 13 A Forked Dipole antenna 13 1 13 1 Forked dipole mod l lt lt oS OR AAA BESS SOROS 13 1 E II 13 2 14 Different ways to feed a horn antenna 14 1 141 TIT ear RA SIA AAA AA 14 2 14 2 Waveguide feed 2 4 5 4 0s ee ewe eee Ree EE HR EHO DORE HE EGS 14 4 LS DEMI sn ge oe hs eh HARARE PAA ADA AAA RRS 14 4 144 FEM modal port 56466656 ANGE SENSE
114. nate system with radius 1 3 w_1 and the number of 0 and q points is equal to 34 and 71 respectively Requesting calculations Ensure that the 3D far field is still requested from the previously generated model Also request a near field with Save the file and run the solver 25 4 Spherical excitation and LE PO reflector In this model the far field that was stored in the sph file from the horn model is used As for the previous model when the near fields were used the horn is removed from the full model and replaced by an equivalent source July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 5 Creating the model The original model is opened again and saved with a different name The horn is removed and a new excitation is created for the dish The steps for setting up the model containing the reflector and equivalent spherical mode source are as follows e Open the original model and save it under a new name e Remove the waveguide excitation and port e Remove the horn from the model e Create a new spherical mode source at w_1 0 0 Select the sph file that has been created during the previous simulation Requesting calculations No calculation requests need to be created since the far field request was created in the original model and it has not been removed Save the file and run the solver 25 5 Comparative results The required resources memory and CPU time is listed in Table 25 1 It
115. nd 2 steps Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings notes and errors Please correct error before running the FEKO solution kernel 21 2 Results The solution required 52 seconds on an Intel R Core TM 2 E8200 CPU 2 67GHz For com parison the MoM result required about 160 MByte of RAM and 65 seconds solution time As the problem size increases the difference will become more and more significant Memory and other detailed information is available in the out file as shown in the following extract for the MLFMM solution SUMMARY OF REQUIRED TIMES IN SECONDS Reading and constructing the geometry Checking the geometry Initialisation of the Greens function Calcul of coupling for PO Fock Ray launching phase of GO Calcul of the FMM transfer function Fourier transform of FMM basis funct Calcul of matrix elements Calcul of right hand side vector Preconditioning system of linear eqns Solution of the system of linear eqns Calcul of far field other total times total times in hours CPU time runtime 0 313 0 313 0 094 0 094 0 031 0 031 0 016 0 016 0 000 0 000 0 188 0 188 0 781 0 781 41 516 41 516 0 062 0 062 4 859 4 859 3 297 3 297 0 422 0 422 0 781 0 781 52 469 52 469 0 015 0 015 Peak memory usage during the whole solution 159 007 MByte Figure 21 2 compares the results obtained wit
116. ng between two horns as shown in Figure 24 1 Full Model cfx The reference model used to compute the coupling between two horn antennas located as shown in Figure 24 1 directly without using a pre computed far field pattern 24 1 The horn antenna in free space In the Pyramidal_Horn cfx model the 3D radiation pattern of a horn at 1 645 GHz is com puted and saved to an ffe file The horn is excited using a waveguide port The horn is placed with its excitation on the yz plane To account for the phase centre offset the far field is calculated with the offset axis origin at x 21 6 cm The calculation of the phase centre required for accurate placement of the radiation pattern representation of the horn is beyond the scope of this example but it is discussed in Example 35 of the ScriptExamples pdf guide Technically the phase offset needs to be calculated for each frequency as well as the far field pattern but since the bandwidth of the calculation is very narrow and for demonstration purposes this is neglected here Two planes of symmetry are used in the model July 2011 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTENNA 24 2 24 2 Using the computed horn radiation pattern in a coupling calculation In Point_Source_Coupling cfx the two horn antennas are substituted with correctly ori ented and positioned ideal receiving antenna and radiation pattern point sources Here the coupling can be computed based
117. ng the defini tion method Base centre width depth height top width top depth The bottom width and bottom depth are wa and wb The height top width and top depth are hl ha and hb respectively e Set the region of the flare to free space Also delete the face at the origin as well as the face opposite to the face at the origin e Create the feed pin as a wire element from 0 wb 2 f1 to 0 wb 2 pinlen f1 e Add a wire segment port on wire The port must be placed where the pin and the waveguide meet e Add a voltage source to the port 1 V 0 e Union the three parts e Set the frequency to freq e Set the total source power no mismatch to 5 W Requesting calculations One plane of magnetic symmetry in the x 0 plane may be used The solution requests are e Define a vertical cut far field request YZ plane in 2 steps for the E plane cut e Define a horizontal cut far field request XZ plane in 2 steps for the H plane cut Meshing information Use the coarse auto mesh setting with a wire radius of 0 1 cm We use coarse meshing for this example to keep the simulation times as low as possible July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 4 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 14 2 Waveguide feed Creating the model The wire feed model is
118. nna radiation pattern far field input impedance infinite ground FEM current source modal excitation waveguide port The dielectric resonator antenna DRA example illustrates how a coaxial pin feed can be mod elled The input impedance and radiation pattern of a DRA on a finite ground plane are con sidered Two methods for feeding the model are considered One method uses a FEM MoM hybrid whilst the other uses a pure MoM approach For the FEM model a layer of air is added to minimise the number of triangles on the FEM MoM interface The antenna geometry including the finite ground plane and a symmetry plane is shown in Figure 12 1 AAA AE VEAIS Figure 12 1 Semi transparent display of a dielectric resonator antenna on a finite ground plane showing the dielectric resonator and feed pin 12 1 DRA fed with a FEM modal port Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define variables epsr 9 5 Relative permittivity lambda_0 c0 6e9x1000 Free space wavelength in millimetres r 0 63 Feed element radius hBig 1 Feed base height rBig 2 25 Feed base radius rDisk 60 The ground radius 12 5 The inner dome radius rDome July 2011 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND 12 2 tLO lambda_0 9 Local mesh size rDomeBig rDome tLO Outer dome radius h 7 Fee
119. nning the FEKO solution kernel July 2011 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING 17 4 17 2 Results The results as shown in Figure 17 2 indicate that the GO solution agrees very well with both the reference and a solution where the FEM technique was applied to the dielectric lens in the model The effect of the lens on the antenna radiation pattern is clear for all cases When compared to the GO ray launching solution the FEM solution requires considerably more computational resources and runtime Vertical Cut YZ Plane FEM GO Excitation Gain dBi 0 30 60 90 120 150 180 Theta deg Figure 17 2 The computed radiation pattern compared to the reference solution and a full FEM result July 2011 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE 18 1 18 Calculating field coupling into a shielded cable Keywords cable modelling cable analysis shielded cable coupling EMC The coupling from a monopole antenna into a nearby shielded cable that follows an arbitrary path near a ground plane is calculated from 1 MHz to 35 MHz in this example The cable analysis option in FEKO is used for the analysis This method solves the model without the cable first and then calculates the coupling into the cable using the transfer impedance of the cable The same problem could be modelled by building a full MoM model of the cable but that would be much more resour
120. ntenna and a Yagi Uda antenna located in front of an electrically large metal plate as shown in Figure 23 1 This is an electrically large problem and two approaches are used to accelerate the solution significantly The plate is efficiently modelled as an UTD plate and the helix antenna is modelled as an ideal receiving antenna based on a pre computed far field data from a helix model in free space The ideal receiving antenna formulation can be used only when far field data is available or can be calculated in a separate simulation for an antenna In addition the antenna must be located an acceptable distance from all other physical structures that may influence the currents on the antenna Figure 23 1 Geometry of Antenna_Coupling showing full helix model Three models are provided for this example Antenna_Coupling_Helix_Antenna cfx Model of the helix antenna used to pre calculate the far field pattern that is used in the ideal receiving antenna Antenna_Coupling Receiving _Antenna cfx The model used to calculate the coupling be tween the Yagi Uda and helix antennas using the ideal receiving antenna based model for the helix Antenna_Coupling_Full cfx The model used to calculate reference result using the full models for both antennas 23 1 The helix antenna in free space Creating the model The steps for setting up the model are as follows e Define variables July 2011 FEKO Examples Guide ANTENNA COUPLING USING AN ID
121. o 0 25 July 2011 FEKO Examples Guide MICROSTRIP PATCH ANTENNA 10 3 CEM validate After the model has been meshed run CEM validate 10 2 Pin fed planar multilayer substrate Creating the model The substrate is now modelled with a planar multilayer substrate Green s Functions It is still pin fed as in the previous example Figure 10 2 A 3D representation of a pin fed microstrip patch antenna on an infinite ground The model is extended with the following steps performed sequentially e Copy the patch and feed pin from the tree e Change the port so that it is now located on the wire that has been copied e Delete the antenna part e Union the patch and the wire e Add a planar infinite multilayer substrate infinite plane with a conducting layer at the bottom LayerO should be free space and layer1 must be set to substrate with a height of Hs The meshing values can remain unchanged the values used for the previous simulation are sufficient Run CEM validate Note that a warning may be encountered when running the solution This is because losses that may be required when directivity has been requested can not be calculated in an infinitely large medium This warning can be avoided by requesting that the far field gain be calculated instead of the directivity on the Advanced tab of the far field request dialog in CADFEKO July 2011 FEKO Examples Guide MICROSTRIP PATCH ANTENNA 10 4 10 3 Edge fed
122. o obtain the same results July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 6 Far Field Gain MLFMM MoM LE PO Aperture LE PO Spherical LE PO Gain dB Theta deg Figure 25 2 Gain of the reflector antenna calculated using different techniques over a 180 degree angle Far Field Gain MLFMM MoM LE PO Aperture LE PO Spherical LE PO Gain dB 85 86 87 88 89 90 Theta deg Figure 25 3 Gain of the reflector antenna calculated using different techniques main lobe July 2011 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA 26 1 26 Using a non radiating network to match a dipole antenna Keywords network S parameters Z parameters Y parameters Touchstone ideal matching dipole A short dipole approximately 3A is made resonant at 1 4 GHz using a simple LC matching section The dipole is first constructed in CADFEKO and then the matching network is included using a non radiating network defined in EDITFEKO This example requires the S parameters of the matching section to be computed successfully The matching section S parameters pre computed in a third party tool are provided in the Matching s2p Touchstone file The matching network is simply a 2 1 pF shunt capacitor and a 43 4 nH series inductor connected between the excitation and the dipole Figure 26 1 is an illustration of the short dipole with a network feed as well as the m
123. om the model provided for this example in Fig ure 8 2 As expected the ground plane greatly influences the radiation pattern Note that the graph is a vertical polar plot of the gain in dB for the two cases Far Field Above Inf Ground No Ground 300 270 240 180 Figure 8 2 The gain pattern of the Yagi Uda antenna over a real ground and without any ground July 2011 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA 9 1 9 Pattern optimisation of a Yagi Uda antenna Keywords antenna Yagi Uda radiation pattern optimisation In this example we consider the optimisation of a Yagi Uda antenna consisting of a dipole a reflector and two directors to achieve a specific radiation pattern and directivity requirement The frequency is 1 GHz The antenna has been roughly designed from basic formulae but we would like to optimise the antenna radiation pattern such that the directivity is above 8 dB in the main lobe 30 lt lt 30 and below 7 dB in the back lobe 62 lt y lt 298 Figure 9 1 A 3D view of the Yagi Uda antenna 9 1 The antenna Creating the model The steps for setting up the model are as follows e Define the following variables physical dimensions based on initial rough design freq lambda LO 0 Li L2 L3 50 S1 S2 O O O O O O 1e9 The operating frequency c0 freq The wavelength in free space at the operating frequency
124. or an aperture coupled patch antenna No of RAM MB Time min sec Model Triangles Finite ground Full SEP 3828 483 24 1 Infinite ground Aperture triangles 650 3 85 3 34 Table 34 1 has shown the improvement in resource requirements for running the planar multi layer substrate version of the model The results shown in Figure 34 2 indicate that the model is a good approximation of the full SEP model If one increases the size of the finite substrates the results are expected to converge even more as the infinite plane approximation becomes more appropriate Excitation Infinite aperture elements Finite SEP Figure 34 2 Smith chart showing the reflection coefficient over frequency for the two models Figure 34 3 shows the far field at broadside over frequency The far fields are the same shape and the resonant frequency deviates by less than 1 July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 6 Far Field Infinite aperture elements Finite SEP Realised gain 2 10 2 12 2 14 2 16 2 18 2 20 2 22 2 24 2 26 2 28 2 30 Frequency GHz Figure 34 3 Far field realised gain over frequency 0 0 p 0 July 2011 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES 35 1 35 Antenna radiation hazard RADHAZ safety zones Keywords yagi radiation hazard scr
125. planar multilayer substrate Creating the model This third model is an extension of the second model The patch is now edge fed and the mi crostrip feed is used NOTE This example is only for demo purposes Usually the feed line is inserted to improve the impedance match Also for improved accuracy the edge source width here the width of the line of 4 5 mm should not be wider than 1 30 of a wavelength This means that strictly speaking the microstrip port should not be wider than about 3 mm Figure 10 3 A 3D representation of an edge fed microstrip patch antenna on an infinite ground The modification is shortly as follows e Only the patch is copied out of the antenna part e Delete the voltage source port mesh and antenna part from the model e Define a new variable feedline_width 4 5 e Create a workplane by snapping to the centre of the side of the rectangle equal to W Rotate the workplane around the U V and or N axis until the correct orientation is displayed e Create a line in the middle of the edge equal to W The length of the line is equal to feedline_width e Sweep the line lambda 4 a quarter wavelength away from the patch e Union all the elements e Add a microstrip port at the edge of the feed line e Add a voltage source on the port 1 V 0 All meshing and calculation requests can remain the same as in the previous example Run the CEM validate July 2011 FEKO Examples Guide MICROSTRIP PA
126. rce to the port 1 V 0 e Set the total source power no mismatch equal to 10 W e Define a PEC ground plane reflection coefficient approximation e Set the frequency to be continuous from 1 MHz to 35 MHz Requesting calculations The cable definitions that were defined in the previous section is now used to create a cable harness Create a cable harness with the cable path and cable definitions that were created This example is an irradiating susceptibility cable example using the MTL solution method Add four loads two on each side of the cable A 50 Q load is required from the centre conductor to the cable shield on each side of the cable The cable shield also needs to be shorted to ground zero resistance Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 18 2 Results Results are shown in Figure 18 2 July 2011 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE 18 3 Load 1 0 1 gt 0 01 g 2 S 0 001 0 0001 0 00001 0 5 10 15 20 25 30 35 Frequency MHz Figure 18 2 Voltage induced in a terminated shielded cable by an external source vertical axis is on a log scale July 2011 FEKO Examples Guide A MAGNETIC FIELD PROBE 19 1 19 A magnetic field probe Keywords shielding EMC probe cur
127. rent plane wave magnetic field A magnetic field probe in the form of a frame antenna with shielding against electric fields is con structed and simulated The wavelength at the operating frequency 30 MHz is approximately 10 m Figure 19 1 A 3D view of the H probe and the plane wave incidence excitation symmetry plane shown 19 1 Magnetic field probe Creating the model The steps for setting up the model are as follows e Define the following variables freq 30 6 The operating frequency lambda cO freq The free space wavelength rBig 1 Radius of revolution rSmall 0 1 The pipe radius e Create an ellipse with equal radii at 0 0 0 with its face in the y axis direction radius rSmall1 Set the workplane of the ellipse at an origin of rBig 0 0 and set the U and V vector respectively to 0 0 1 and 1 0 0 e Rotate the ellipse over an angle of 175 degrees around the z axis e Spin the ellipse over an angle of 350 degrees around the z axis e Set the region to free space e Delete the faces at the end and beginning of the toroidal section e Draw an elliptic arc through the centre of the toroidal section radius rBig start angle 0 end angle 360 July 2011 FEKO Examples Guide A MAGNETIC FIELD PROBE 19 2 e Add a plane wave excitation that loops over multiple incidence angles Let 0 lt 9 lt 90 and p 0 10 steps Set the polarisation angle equal to 90 e Set
128. resource requirements some local mesh refinement is necessary on several of the geometry parts Set the local mesh refinement for the patch edges to lambda_b 40 Set local mesh refinement on the aperture face to ap_w 0 7 e Set the continuous frequency range from f_min to f_max Requesting calculations Request a full 3D far field Magnetic symmetry may be applied to the plane at x 0 Meshing information Use the standard auto mesh setting Note that local mesh refinement was used on some of the edges see description above CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 5 34 3 Results Using the correct method to model a problem can dramatically decrease runtime and reduce memory required In this case the aperture triangles are used in conjunction with planar multi layer substrates in such a way as to reduce the mesh size of a model which leads to a reduction in resource requirements Table 34 1 shows the resources required for the two models Note that the two models each sampled a different number of discrete frequency points which affects the total runtime When the time taken per frequency point is considered the runtime improvement becomes more obvious Table 34 1 Comparison of resources using different techniques f
129. rnd_1 Label the plate ground e Create the aperture using a plate with its centre at 0 0 0 a width of ap_1 and a depth of ap_w Label the plate aperture e Subtract aperture from ground Note that the ground plane remains but with a hole in the centre where the aperture plate was defined e Create the patch antenna using a plate with its centre at 0 0 d_b a width of patch_w and a depth of patch_1 Label the plate patch e Create the microstrip feed line using a plate with a base corner at feed_w 2 feed_1 stub_1 d_a a width of feed_w and a depth of feed_1 Label the plate feed e To excite the model an edge feed will be used A plate is created that connects the ground plane to the microstrip line This plate is then split in two parts one for the positive and negative terminals of the excitation e Create the feed port by using a plate The origin of the workplane sits at feed_w 2 feed_1 stub_1 d_a Rotate the workplane by 90 around the u axis so that the plane where the plate will be created is the vertical xz plane and is located at the end of the microstrip line The corner of the plate is at 0 0 0 has a width of feed_w and a depth of d_a Label the plate feedPort e The feed port must still be split into the positive and negative terminals Use the split command Split feedPort in the uv plane at 0 0 d_a 2 e At this point all of the PEC parts have been created that are required for the model
130. rth example uses a FEM modal boundary The waveguide feed section of the horn is solved by setting it to a FEM region The waveguide is excited using a FEM modal boundary Note that for this type of port any arbitrary shape may be used and the primary mode will be calculated The forth example does not build on any of the previous models and it constructed as a new model Figure 14 5 FEM modal port feed 14 1 Wire feed Creating the model The steps for setting up the model are as follows e Set the model unit to centimetres e Create the following variables freq 1 645e9 The operating frequency lambda c0 freq 100 Free space wavelength wa 12 96 The waveguide width wb 6 48 The waveguide height July 2011 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA 14 3 ha 55 Horn width hb 42 80 Horn height wl 30 20 Length of the horn section fl wl lambda 4 Position of the feed wire in the waveguide hl 46 Length of the horn section pinlen lambda 4 56 Length of the pin e Create the waveguide section using a cuboid primitive and the Base corner width depth height definition method The Base corner is at wa 2 wb 2 w1 width of wa depth of wb and height of wl in the y direction e Set the region of the of the cuboid to free space and delete the face lying on the uv plane e Create the horn using the flare primitive with its base centre at the origin usi
131. sed in the z 0 plane The solution requests were e Create a vertical far field request 0 lt lt 180 and p 0 e Create a near field request along the z axis Note that a near field request can not be on a mesh segment To overcome this situation we simply move the requested points slightly Set the Start position for the near field to 0 0 2 R 0 01 and the End position to 0 0 2 R Also set the z Increment to R 20 Meshing information Use the custom mesh option with the following settings e Triangle edge length 0 2 e Wire segment length Not applicable e Tetrahedral edge length Not applicable e Wire segment radius Not applicable Since the wavelength at the simulation frequency large compared to the size of the model we need to mesh the model such that it accurately represents a sphere A triangle edge length of 0 2 is fine enough to accurately represent the sphere CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 4 2 Results Figures 4 2 and 4 3 compare the near field along the z axis and the radar cross section as a function of the angle to exact mathematical results RCS calculations are displayed on a far field graph The y axis of the RCS graph has been changed to a logarithmic scale for improved visualisation July 2011 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE 4 3
132. sing MLFMM The MLFMM solution is used as the reference solution in the results section 25 5 e Large element physical optics LE PO can be used on sub parts of the model e Subdivide the problem and use an equivalent source Possible equivalent sources are Aperture source using the equivalence principle a region can be replaced by equiv alent electric and magnetic field sources on the boundary of the region Spherical modes source the far field can also be used as an impressed source 25 1 MoM horn and LE PO reflector The first example creates the horn and the dish The horn is simulated using the method of moments MoM and the dish reflector is simulated using large element physical optics LE PO July 2011 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR 25 2 Creating the model The model is created in two parts first the horn is created and then the parabolic dish is created Start by defining the following variables freq 12 5e9 The operating frequency lam cO freq Free space wavelength lam_w 0 0293 The guide wavelength h_a 0 51 1lam The waveguide radius h_b0 0 65 1am Flare base radius h_b lam Flare top radius h_1 3 05x 1lam Flare length ph_centre 2 6821e 3 Horn phase centre R 18 1lam Reflector radius F 25 1am Reflector focal length w_l 2 lam_w The waveguide length The steps for creating the horn are as follows Create a cylinder along th
133. te modelled with the thin dielectric sheet approximation is illuminated by an incident plane wave such that the bistatic radar cross section may be calculated at 100 MHz Figure 3 1 A 3D representation of a thin dielectric sheet with a plane wave excitation excitation and symmetry planes shown 3 1 Dielectric sheet Creating the model The steps for setting up the model are as follows e Define the following variables freq 100e6 Operating frequency d 0 004 Plate thickness 2 Length of plate b 1 Width of plate epsr 7 Relative permittivity a tand 0 03 Loss tangent thetai 20 Zenith angle of incidence phii 50 Azimuth angle of incidence etai 60 Polarisation angle of incident wave July 2011 FEKO Examples Guide RCS OF A THIN DIELECTRIC SHEET 3 2 e Create a dielectric called substrate with relative permittivity equal to epsr and dielectric loss tangent set the variable tand e Create a layered dielectric with a single layer named thin_dielsheet Select substrate as the layer and set the thickness equal to variable d e Create a rectangular plate in the x y plane centred around the origin The width x axis is 2 m and depth is 1 m e Set the face properties of the plate to be a Thin Dielectric Sheet with the medium name set to thin_dielsheet e Add a single incident plane wave excitation from the direction O thetai and p phii Set the polarisation angle to
134. te the patch by creating a rectangle with the base centre width depth height defini tion method The base centre should be located at 0 0 base_height Set the width and depth respectively to the defined variable patch_length and patch_width e Union the cuboid and the rectangle e Create the feed pin as a wire between the patch and the bottom of the substrate Set the Start point to pin_pos 0 0 and the End point to pin_pos 0 base_height e Union all the elements and label the union antenna e Set the region of the cuboid to substrate e Set the faces representing the patch and the ground below the substrate to PEC e Add a segment wire port on the middle of the wire e Add a voltage source on the port 1 V 0 e Set the frequency to freq e Set the periodic boundary condition of the model to the end exactly on the edge of the substrate to expand in both the x and y dimensions e Manually specify the phase shift in both directions to be uJ 0 and u2 0 Requesting calculations The solution requests are e Create a vertical E plane far field request 180 lt lt 180 with 0 1 and 0 incre ments e Create a vertical E plane far field request 180 lt lt 180 with 0 1 and 0 incre ments Request the calculation of a 10 by 10 array of elements Advaced tab Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 0001 CEM validate After the mod
135. time domain and Figure 33 3 the back scattered electric far field E 1 0 0 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 Normalised Ez 0 0 0 15 20 25 30 Time in light metre Figure 33 2 Time response of the excitation 35 July 2011 FEKO Examples Guide A TIMEFEKO EXAMPLE 33 5 200 100 100 Farfield E Field mV 200 300 0 5 10 15 20 25 30 35 40 Time in light metre Figure 33 3 Response of the back scattered far field E of the cube July 2011 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA 34 1 34 Modelling an aperture coupled patch antenna Keywords aperture triangles infinite planes SEP A patch antenna can be fed using a microstrip feedline coupling energy through an aperture in the ground plane underneath the patch This example will demonstrate how to model such a configuration using both a full model where the substrates are meshed as well as an infinite plane approximation The latter makes use of aperture triangles that cut allows energy to couple through an infinite PEC ground plane Figure 34 1 shows a depiction of the geometry that will be used Figure 34 1 Top view of an aperture coupled patch antenna Opacity has been set so that all layers can be seen in the image 34 1 Aperture coupled patch antenna Full SEP model Creating the model The steps for setting up the model are as follows e Define the following variables f_min 2
136. tion Radiating Re Z Radiating Im Z Non radiating Re Z Non radiating Im Z SS Impedance Ohm lt 1 9 2 0 2 1 2 2 2 3 24 25 2 6 2 7 2 8 2 9 Frequency GHz Figure 27 2 Input impedance real and imaginary of the path with radiating and non radiating feed July 2011 FEKO Examples Guide LOG PERIODIC ANTENNA 28 1 28 Log periodic antenna Keywords Transmission line dipole array far field A log periodic example uses the non radiating transmission lines to model the boom of a log periodic dipole array antenna The antenna is designed to operate around 49 26 MHz with an operational bandwidth over a wide frequency range 35 MHz to 60 MHz Figure 28 1 shows the log periodic dipole array LPDA with a transmission line feed network Figure 28 1 The model of LPDA using transmission lines to model the boom structure 28 1 Log periodic dipole array Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Create the variables required for the model freq 46 29e6 The operating frequency tau 0 93 The growth factor Sigma 0 7 Spacing lenO 2 Length of the first element dO 0 Position of the first element rado 0 00667 Radius of the first element lambda c0 freq Free space wavelength Zline 50 Transmission line impedance Zload
137. tion Use the standard auto mesh setting with wire segment radius 0 1 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors correct any errors before running the FEKO solution kernel Save the file and run the solver 26 2 Dipole matching using a general s parameter network Use the same model as for the SPICE matching network model Change the general network settings to refer to an S matrix Touchstone file named Matching s2p This file defines the S parameters of the matching network Port 1 of this general network is ex cited using a voltage source excitation The second port is connected to the wire port in the centre of the wire Requesting calculations No solution requests are required in CADFEKO July 2011 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA 26 3 Meshing information Use the standard auto mesh setting with wire segment radius 0 1 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver 26 3 Results The reflection coefficient of the matched and unmatched dipole is shown in Figure 26 2 It may be difficult to see any variation of the reflection coefficient of the unmatched dipole since it is very close to O dB over the whole band Reflection coefficient Not matched SPICE
138. to be used on the plate must be changed This change is made by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Geometrical optics GO ray launching Requesting calculations No changes are made to the solution requests for the MoM GO case As with the MoM model the two planes of symmetry should be used to accelerate the solution speed and reduce resources Meshing information Use the standard auto mesh setting with the wire radius set to rho After changing the solution method on the plate to GO the model must be remeshed The triangle sizes are determined by the geometrical shape and not the operating wavelength Unlike the UTD plate the plate will be meshed into triangular elements for the GO CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Note that a warning may be encoun tered when running the solution This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the Advanced tab of the far field request in the tree July 2011 FEKO Examples Guide DIPOLE IN FRONT OF A UTD GO PO PLATE 16 4 16 4 Dipole and a PO plate Creating the model The model is identical to the MoM model The only change that is required is that the solution
139. trip lines faces of strip_width 0 7 July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 6 Requesting calculations The solution requests are e Create an S parameter request with Portl active and 50 reference impedances Port 2 should be added but not be active Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 15 4 Results The S parameters for all 3 cases are computed over the frequency range 1 5 GHz to 4 GHz The results for the S parameters are shown in Figure 15 4 and 15 5 From the scattering parameters at the input and output ports it can be seen that almost all energy incident on the filter at 2 75 GHz is reflected back to the input port The effect of the different solution methods and feed techniques can be seen in the results but all results agree very well with the reference measurements and with each other S parameter Fin substrate FEM Inf substrate GF Fin substrate SEP S parameters dB 415 2 0 25 3 0 3 5 4 0 Frequency GHz Figure 15 4 S in dB of the microstrip filter on an infinite and finite substrate from 1 5 GHz to 4 GHz July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 7 S parameter S parameters dB Fin substrate FEM Inf substrate
140. uency equal point at 3 GHz The meshed geometry is shown in Figure 11 1 Note that the infinite plane Green s function has been removed from the view The feed line of the patch is between the patch and the ground plane h Figure 11 1 Proximity coupled circular patch antenna The lighter triangles are on a lower level closer to the ground plane 11 1 Circular patch Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define some variables epsr 2 62 The relative permittivity patch_rad 17 5 The patch radius line_len 79 The strip line length line_width 4 373 The strip line width offset 0 Feed line offset from the patch centre substrate_d 3 18 The substrate thickness July 2011 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED 11 2 e Create a new dielectric medium called substrate with relative permittivity of epsr and dielectric loss tangent of 0 e Create a circular metallic disk with centre of the disc at the origin with radius patch_rad e Create a rectangle with the definition method Base corner width depth e Set the Base corner as the following line_width 2 0 substrate_d 2 Set the width line_width and depth line_len e Adda planar multilayer substrate The substrate is substrate_d thick and is of substrate material type with a bottom ground plane Layer0 is of type free space
141. use CADFEKO for the model geometry creation and the solution set up and only to use scripting for advanced options and adjustment of the model for example the selection of advanced preconditioner options The last way is to use the scripting for the entire model geometry and solution set up In this document the focus is on the recommended approaches primarily using the CADFEKO user interface with no scripting Examples that employ only scripting are discussed in the Script Examples guide These exam ples illustrate similar applications and methods to the examples in the Examples guide and it is highly recommended that you only consider the Script Examples if scripting only examples are specifically required It is advisable to work through the Getting started guide and familiarise yourself with the Working with EDITFEKO section in the FEKO Users Manual before attempting the scripting only examples Running FEKO LITE FEKO LITE is a lite version of the FEKO Suite which is limited with respect to problem size and therefore cannot run all of the examples in this guide For more information on FEKO LITE please see the Getting started manual and the Installation Guide What to expect The examples have been chosen to demonstrate how FEKO can be used in a selection of applica tions with a selection of the available methods Though information regarding the creation and setup of the example models for simulation is discussed these example
142. ution requests are e Create an S parameter request with Portl active and 50 reference impedances Port 2 should be added but not be active Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel July 2011 FEKO Examples Guide A MICROSTRIP FILTER 15 4 15 2 Microstrip filter on a finite substrate SEP Creating the model The model is based on the FEM model described above In order to use the SEP we must change the meshing no volume mesh elements are required and the excitation method must be ad justed The steps for modifying the the FEM model are as follows e Delete the S parameter request and both of the line ports including the line geometry used to define the port locations e Set the region properties of the two regions back to MoM MLEMM with surface equivalence principle SEP default Also set the air region back to Free space e As described in the note below we need to create an excitation point inside the dielectric region In order to do this create a face extending from the microstrip edge down to the ground plane just inside the dielectric region as shown in Figure 15 3 The simplest way to do this is to select and copy the edges at the microstrip line feed points and sweep them down to the ground to create a plate e Split th
143. wer operating frequency f_max 100e6 Upper operating frequency d 2 5e 9 Thickness of the shell sigma 6 1e7 Conductivity of silver e Create a new metallic medium with conductivity set equal to the variable sigma Label the medium lossy_metal July 2011 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY 5 2 e Create a sphere at the origin with radius set equal the defined variable roO e Set the region of the sphere to free space e Set the medium type of the sphere s face to Lossy conducting surface Choose lossy_metal as the medium and set the thickness equal to the variable d e Create an single incident plane wave with direction set to 0 90 and 180 e Set the frequency to calculate a continuous range between f_min and f_max Requesting calculations In the X 0 plane use geometric symmetry In the Y 0 use magnetic symmetry and in the Z 0 plane use electric symmetry The solution requests are e Create a single point near field request in the centre of the sphere Use the Cartesian coordinate system Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel 5 2 Finite conductivity sphere Finite Element Method Creating the model The steps for setting up the model are as follows e Define the
144. ywords ADAPTFEKO continuous sampling We will consider the input admittance of a simple forked dipole as shown in Figure 13 1 This example is based on the paper Efficient wide band evaluation of mobile communications 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 Propagation vol 47 pp 65 76 January 1999 where the input admittance of a forked monopole is considered Figure 13 1 The forked dipole geometry 13 1 Forked dipole model Creating the model The model is very simple and can be created as follows e Create the following variables freq 3e8 The operating frequency e Create the following named points pointi 0 01 0 0 5 point2 0 0 0 01 point3 0 01 0 0 466 point4 0 0 0 01 July 2011 FEKO Examples Guide A FORKED DIPOLE ANTENNA 13 2 e Create 2 line primitives One from pointi to point2 and a second from point2 to points e Apply a copy special Copy and mirror operation on the two lines The mirror operation should be around the uv plane e Create a line primitive between the named points point2 and point4 Label this line as feed e Union all of the lines into a single part e Add a wire port to the middle of the feed wire e Apply a voltage excitation 1V 0 to the port e Set the solution frequency settings to Continuous interpolated range between 100 MHz and 3

Download Pdf Manuals

Related Search

Related Contents

事先明書 - 三菱電機  Liste des MDPH  Manual-Fire-FanTestic Integrity (ISO)  Guía de Unitron uDirect™ 2  Notice produit  USER MANUAL    DCLI Deeter Current-Loop Indicator User Manual. Packing list    MANUAL DE USUARIO  

Copyright © All rights reserved. Failed to retrieve file