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P C A A D 6.0 - Antenna Design Associates

1. Quantity PCAAD PCAAD exact numerical aperture efficiency 75 75 directivity 48 7 dB 48 7 dB 3 dB beamwidth 0 67 0 63 Validation 2 A prime focus reflector has a diameter of 100 cm f D 0 5 and operates at 30 GHz The feed is a short dipole with an E plane pattern of cos 0 and an H plane pattern that is constant these data files named paraE dat and paraH dat are supplied with PCAAD The calculated pattern in the d 45 plane is presented in reference 3 showing a maximum cross pol level of 26 dB and a maximum sidelobe level of 20 dB The calculated patterns from PCAAD are shown below with results in agreement with these values Reflector Co pol 10 M Pattern dB 30 Figure 6 Calculated co pol blue and cross pol black patterns for the parabolic reflector antenna in the 45 plane 73 F The Microstrip Antennas Menu This set of six routines implement cavity model solutions for rectangular and circular microstrip antennas Two different solutions are available for probe fed rectangular patches as well as solutions for a microstrip line fed rectangular patch a proximity coupled rectangular patch an aperture coupled rectangular patch and a probe fed circular patch In general cavity model solutions work well for microstrip antennas on thin substrates but fail for substrates thicker than about 0 02A Subject to this limitation these routines can be used to get a reasonably good esti
2. F 6 Circular Probe Fed Patch Analysis This routine analyzes a circular probe fed microstrip antenna using a cavity model similar to that discussed in reference 9 The patch is treated as a lossy cavity to account for radiation and length extensions are used to account for fringing fields at the patch edge A parallel RLC equivalent circuit is then used to compute the input impedance versus frequency The la radiation patterns are found from the equivalent magnetic currents for the dominant TM mode The directivity is calculated by integrating the far field patterns This solution generally gives good results for microstrip antennas on thin substrates with low dielectric constants Enter the patch radius the radial distance to the feed probe the substrate thickness the dielectric constant and the dielectric loss tangent The routine will then estimate the resonant frequency of the antenna and suggest a frequency step size These values are displayed along with the default number of frequency points in three boxes to the right of the Compute button Click the Compute button to accept these values for the frequency sweep or enter new values for the sweep center frequency the frequency step size or the number of frequency points The routine will then compute the input impedance of the antenna over this frequency sweep and display the results in the list box If necessary use the scroll bar at the right of the box to sc
3. 4 Paste Text 20 5 Edit File 20 6 Print Window 21 C The Wire Antennas Menu 22 1 Wire Dipole Antenna Analysis 22 2 Wire Dipole Radar Cross Section Analysis 24 3 V Dipole Antenna Analysis 26 4 Wire Loop Antenna Analysis 28 5 Yagi Dipole Array Analysis 6 Finite Wire Dipole Array Analysis 7 Log Periodic Dipole Array Design 8 Log Periodic Dipole Array Analysis 9 General Wire Antenna Analysis D The Array Antennas Menu 1 Uniform Linear Array Design and Analysis 2 Linear Subarray Design and Analysis 3 Uniform Rectangular Array Design and Analysis 4 Uniform Circular Planar Array Design and Analysis 5 Arbitrary Planar Array Design and Analysis 6 Infinite Printed Dipole Array Analysis 7 Woodward Lawson Linear Array Pattern Synthesis 8 Grating Lobe Diagram for a Planar Array 9 Effect of Array Excitation Errors and Failed Elements E The Aperture Antennas Menu j i Traveling Wave Line Source Analysis Rectangular Aperture Antenna Analysis Circular Aperture Antenna Analysis E and H Plane Sectoral Horn Analysis Pyramidal and Corrugated Pyramidal Horn Analysis Diagonal Horn Analysis Conical and Corrugated Conical Horn Analysis Approximate Parabolic Reflector Analysis Parabolic Reflector Pattern Analysis OANINNBWN F The Microstrip Antennas Menu 1 Rectangular Probe Fed Patch Analysis Carver model 2 Rectangular Probe Fed Patch Analysis cavity model 3 Rectangular Line
4. For example if the average sidelobe level due to errors is 5 dBi and the error free directivity of the array is 23 dB then the sidelobe level relative to the main beam would be 5 23 18 dB Note that this is a residual sidelobe level caused by errors in contrast to the design sidelobe level that is determined by the amplitude taper The resulting sidelobe level will be the larger of these two levels Thus for the example above if the array were designed for 13 dB sidelobes the average error sidelobe level of 18 dB would probably not be noticeable If however the array were designed for 25 dB sidelobes the actual sidelobe level in the presence of errors would be in the range of 18 dB A separate frame is provide for phase shifter quantization effects Use the list box to enter the number of bits for the phase shifters Once a value is selected the peak phase error degrees will be displayed along with the RMS phase error degrees The RMS phase error value is also transferred to the phase error box in the excitation errors frame for convenience The level of the quantization lobe is also displayed note that this value is given relative to the main beam of the array The quantization lobe is due to the periodic phase error that is introduced when digital phase shifters are used in an array This lobe is often higher than nearby sidelobes especially when a small number of phase shifter bits are used See 26 _for techni
5. now consists of a two element H plane subarray of two dipoles with a spacing of 0 64 The subarray pattern can be calculated using the linear array routine and saved as a data file This data file can then be used in the linear subarray routine with N 4 subarrays and a spacing of 1 2 between subarrays The computed pattern and beamwidth agrees with the pattern obtained from the linear array routine The pattern is shown below Figure 4 Pattern of an array consisting of four two element H plane dipole subarrays 47 D 3 Uniform Rectangular Array Design and Analysis This routine is used to plot patterns and compute the directivity of a rectangular planar array antenna You can specify array size amplitude taper phase distribution and element type The number of elements and the element spacing center to center in each plane can be specified separately Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Note that E plane H plane patterns are not available when the array elements are vertical monopoles Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The directivity of the array can also be calculated As indicated in the picture at the top left of the form the array is assumed to lie in
6. rectangular waveguide analysis routine Section G 5 for convenient calculation of propagation constants higher order mode cutoff frequencies or attenuation Select a waveguide by clicking on the appropriate line in the list box the line will be highlighted then click the Send to Rec WG button The window for the Standard Rectangular Waveguide Data routine will close and the Rectangular Waveguide Analysis window will open with the dimensions for the selected guide automatically entered in the appropriate data boxes 92 G 7 Circular Waveguide Analysis This routine computes the cut off frequencies and propagation constants for the five lowest order modes of a circular waveguide and the attenuation due to dielectric and conductor losses for the dominant TE mode Begin by entering the inside radius of the guide the dielectric constant of the material filling the guide and the operating frequency Click the Compute button and the routine will compute and print the cutoff frequencies of the TE TMo TEx TEo and TM modes if the mode is propagating at the specified frequency the propagation constant will also be printed otherwise it is listed as cut off The formulas used in this routine are standard results as found in reference 10 You can compute attenuation for the dominant TE mode if it is propagating by entering the loss tangent of the dielectric filling material and the conductivity of the waveguide wall
7. you can enter your own values for center frequency frequency step size and the number of frequency points The geometry of the V dipole may be viewed in three dimensions by clicking the Show Geometry button Upon clicking the Compute button the routine will compute the moment method solution for the V dipole and list the input impedance versus frequency in the list box The scroll bar can be used to scroll through the data The gain of the dipole at its beam maximum along the z axis is computed at the center frequency of the frequency sweep At this point you can plot the impedance characteristics versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file The specified patterns are also calculated at the center frequency and may be plotted using the Plot Patterns button or saved to data files After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors 26 Validation 1 Consider a V dipole antenna with arm lengths of 0 25 radius of 0 001A and variable angle Calculated input impedance results from PCAAD are compared with data from 11 using one PWS expansion mode Angle Reference 11 PCAAD 6 0
8. 5 dB while in 2 an approximate result of 9 6 dB is given 44 Validation 4 Consider a 10 element broadside array of isotropic elements with a spacing of 0 54 and a 25 dB Taylor amplitude weighting with n bar 2 Element excitations from 20 are compared with results from PCAAD below Excitations for elements 6 through 10 are symmetric with these Element Reference 20 PCAAD 6 0 1 0 417 0 417 2 0 528 0 528 3 0 709 0 709 4 0 889 0 889 5 1 000 1 000 Validation 5 Consider a 20 element broadside array of isotropic elements with a spacing of 1 2 If the elements are uniformly excited the directivity of this array is Dp N 20 13 dB If phase or amplitude errors are added to the excitations the directivity will be reduced according to the formula D Do 1 o where is the rms error Running PCAAD for a rms phase error of 30 or a rms amplitude error of 3 dB and averaging over ten trials gives the following results oO D D Case rms error formula PCAAD 6 0 no errors 0 13 0 dB 13 0 dB phase errors 30 11 9 dB 11 7 dB amplitude errors 3 dB 12 3 dB 12 4 dB 45 D 2 Linear Subarray Design and Analysis This routine is used to plot patterns of a linear z array antenna composed of elements having an arbitrary element pattern defined by a data file This is useful for analyzing arrays of subarrays y or arrays of elements that are not available through the element menu of the linear array rou
9. Array Design and Analysis This routine is used to plot patterns and 7 compute the directivity of a circular planar x array You can specify the radius of the array element spacing center to center a radial amplitude taper and the element type The grid spacing of the elements is rectangular and the routine calculates the number of elements that will approximately fit within a circular area of the specified radius The amplitude taper is applied linearly in dB in the radial direction assuming 0 dB at the center of the array and an edge taper as specified The element type is selected by clicking the small Select button to the right of the text box for element type Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Note that E plane H plane patterns are not available when the array elements are vertical monopoles Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The directivity of the array can also be calculated As indicated in the picture at the top left of the form the array is assumed to lie in the x y plane if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The pattern is computed using the array facto
10. Compute button These values can be estimated by the routine by clicking the Compute button or you can enter your own values for center frequency frequency step size and the number of frequency points The geometry of the dipole may be viewed in three dimensions by clicking the Show Geometry button Upon clicking the Compute button the routine will compute the moment method solution for the dipole and list the input impedance versus frequency in the list box The scroll bar can be used to scroll through the data The gain of the dipole at its beam maximum is computed at the center frequency of the frequency sweep At this point you can plot the impedance characteristics versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file The specified patterns are also calculated at the center frequency and may be 22 plotted using the Plot Patterns button or saved to data files After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors Validation Consider a half wave dipole with a radius of 0 0012 Calculated input impedance results from PCAAD 6 0 are compared with those from 1 and 11 versus N the number of expan
11. Design McGraw Hill New York NY 1985 6 D M Pozar and D H Schaubert Microstrip Antennas The Analysis and Design of Microstrip Antennas and Arrays IEEE Press New Jersey 1995 7 A W Rudge K Milne A D Olver and P Knight editors Handbook of Antenna Design Vol 2 Peter Peregrinus Press London 1983 8 Y T Lo and S W Lee Antenna Handbook Van Nostrand New York 1988 9 J R James and P S Hall Editors Handbook of Microstrip Antennas Peter Peregrinus Press London 1989 10 D M Pozar Microwave Engineering 3 edition John Wiley amp Sons New York NY 2005 11 J H Richmond Computer Program for Thin Wire Structures in a Homogeneous Medium Technical Report TR 2902 12 ElectroScience Laboratory Ohio State University 12 M Kluskens A New Computer Algorithm for the Complex Exponential Integral in the Method of Moments IEEE Trans Antennas and Propagation vol 47 pp 803 806 May 1999 13 D M Pozar and D H Schaubert Scan Blindness in Infinite Arrays of Printed Dipoles IEEE Trans Antennas and Propagation Vol AP 32 pp 602 610 June 1984 14 K R Carver and J W Mink Microstrip Antenna Technology IEEE Trans Antennas and Propagation vol AP 29 pp 2 24 January 1981 101 15 D M Pozar A Microstrip Antenna Aperture Coupled to a Microstrip Line Electronics Letters Vol 21 pp 49 50 January 17 1985 16 D M Pozar A Reciprocity Method of
12. PCAAD The program can also be closed by clicking the box at the top right of the main window B The Edit Menu Being a Windows application PCAAD 6 0 allows use of the standard Windows methods of cutting copying and pasting data and graphics from PCAAD routines to the Windows clipboard For example you can copy an image of the active window to the Windows clipboard by pressing Alt PrintScreen or copy an image of the entire screen to the clipboard by pressing PrintScreen You can also transfer data from one input box to another by using the Windows clipboard This can be done using the PCAAD functions described below or by using the Ctrl C and Ctrl V keys to respectively copy and paste selected data B 1 Copy Window Copy Window allows you to copy the currently active Window to the Windows clipboard This may then be pasted into another Windows application such as PowerPoint or a word processor This action is similar to pressing Alt PrintScreen which also copies the active Window to the clipboard Note that the entire screen image can be copied to the clipboard by pressing PrintScreen these are standard Windows commands B 2 Copy Graph Copy Graph allows you to copy the current graph or plot to the Windows clipboard The graph or plot may then be pasted into another Windows application such as PowerPoint or a word processor Note that this command only copies the graph or plot not the complete Window B 3 Copy Text To copy a v
13. VGI ZLR ZLI mode number of port real and imaginary generator voltage real and imaginary load impedance one line for each port This data file can be created using a standard text editor see the DIPOLE ANT ARRAY ANT and YAGI ANT files in the PCAAD program directory for examples of how the geometry files can be written PWS modes are laid out along the wires starting from the first endpoint at point I1 to the terminals at point I2 and to the second endpoint at point I3 Note that each arm of a PWS expansion mode must be less than a quarter wavelength long at the operating frequency The routine computes the currents on the wires the input impedance at each port the directivity and gain of the antenna the radiation efficiency and the radiation patterns for the antenna The routine begins with a dialog box to enter a filename for the wire antenna geometry The routine then lists some of the parameters of the wire geometry number of points number of expansion modes and the number of feed ports in 38 three text boxes these can only be changed by changing the geometry data file The routine also reads the operating frequency from the data file but you may enter a different operating frequency if desired Because the polarization of an arbitrary wire antenna is not known E plane H plane patterns and Co pol X pol patterns are not available for this routine but E theta and E phi patterns can be made at an arbitrary azimut
14. a generator however the power lost in that load is included in the antenna loss The logic here is that a realistic source will consist of a voltage generator and a series generator impedance and the power dissipated in the source impedance should not be considered as a loss in the antenna itself Lumped loads apart from the generators will however contribute to antenna loss Thus an antenna with matched generators but without separate lumped loads will have an efficiency of 100 An antenna having resistive lumped loads e g a loaded dipole will have an efficiency less than 100 Validation The Yagi Uda array example described in Section C 5 is used as a validation example for this routine but with one expansion mode per element The data file for this antenna is shown below this file YAGI ANT is supplied with PCAAD 5 0 0 43 225 9 23 9 9 07 0 0 0 0 23 95 0 0 39 2 209 7 0 29 0 5 0725 22 6554 05 29 22 55 0 50 0 7 0s DOs 22 997 OS DOs PCAAD 6 0 produced the following results Input impedance 18 6 j 3 0 Q Gain 9 5 dB Front to back ratio 6 6 dB These results agree with those obtained from the Yagi array routine with one expansion mode per element 40 D The Array Antennas Menu This set of routines can be used to plot patterns for linear rectangular planar and circular planar arrays to compute the input impedance of an infinite array of printed dipoles and to plot a grating lobe diagram
15. and spacings of the elements using the scroll bar and text boxes The name of each element is listed in the box to the right of the scroll bar followed by boxes for its length and spacing from the previous element Thus the spacing of the first element the reflector is not used and is set to zero Use the scroll bar to scroll through the elements to set or change lengths and spacings Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button When all data is entered click the Compute button to calculate the moment method solution The input impedance gain and front to back ratio will be listed The specified patterns are also calculated and may be plotted using the Plot Patterns button or saved to data files You may also save the moment method impedance matrix in a data file The elements in this file are listed in row order for the top triangular half of the impedance matrix the modes are numbered from bottom to top of each element starting at the reflector The geometry of the Yagi array may be viewed in three dimensions by clicking the Show Geometry button After each computation data is automatically written to a log file called WIRE LOG located in the PCA
16. and 100 dB for the axial ratio of the linearly polarized antenna PCAAD gives a minimum and maximum mismatch loss of 3 01 dB as expected Validation 2 Consider a RHCP antenna with an axial ratio of 8 dB and a RHCP antenna with an axial ratio of 4 dB PCAAD gives the minimum and maximum mismatch losses as 0 15 dB and 1 85 dB These values are in agreement with an example in 24 96 H 3 Atmospheric and Rain Attenuation This routine presents a graph of atmospheric attenuation versus frequency along with attenuation due to rain as given in 8 The atmospheric attenuation is at sea level while the rain attenuation is given for three different rain rates Validation At a frequency of 60 GHz the attenuation rate of the atmosphere is 15 dB km At 40 GHz the attenuation due to rain at a rate of 1 mm hr is 0 33 dB km rain at the rate of 16 mm hr increases to 4 9 dB km 97 H 4 Axial Ratio versus Amplitude and Phase Error Many circularly polarized antennas are constructed using two orthogonal linearly Ty 1444 68 polarized antennas fed with equal amplitude excitations that are 90 degrees out of phase As presented in 25 this routine gives the resulting axial ratio due to errors in the actual amplitudes and phases Iy 1 0 Enter the amplitude error in dB and the phase error in degrees The resulting axial ratio is calculated Changing the sign of the amplitude error or the phase error does not ch
17. beam or has more than one main beam e g grating lobes the beam position and beamwidth may not be meaningful and may not be shown The display boxes also show the value of the pattern at the angle indicated by a movable angle cursor The angle cursor is drawn as a dashed vertical line and can be moved by either clicking or dragging with the mouse or by using the left and right arrow keys NumLock must be off When using the mouse notice that the mouse cursor changes from an arrow to a cross hair when moved inside the rectangular plotting region Clicking the mouse inside the rectangular plot will snap the angle cursor to that angular position Alternatively the angle cursor can be moved by clicking the mouse on the angle cursor note that the mouse cursor 15 changes to a directional icon when over the angle cursor and dragging to the desired position The pattern value display is updated instantly Each pattern can be identified with a movable text label The text is set from Plot Options and the labels can be turned on or off using the check box for Show Pattern Labels Use the mouse to drag the label to the desired position on the plot The vertical axis is normally labeled as Pattern dB but this label can be changed by modifying the PCAADS INI file this can be useful when plotting directivity or gain A 3 3 D Pattern Plot This routine plots an antenna radiation pattern in a 3 D volumetric form It can be invoked directly
18. consider the directivity of a single element computed from PCAAD and compared with data from the literature for each of the possible element types 43 Element Literature PCAAD 6 0 Isotropic 0 00 dB 2 0 00 dB Dipole 2 15 dB 2 2 2 dB L A 2 Dipole horizontal 7 17 dB 2 7 2 dB L A 20 4 4 above GP Dipole vertical 6 63 dB 2 6 6 dB L A 20 1 4 above GP Rectangular aperture 30 1 dB 2 30 0 dB L W 10A Circular aperture 29 2 dB 2 29 1 dB radius 5A Rectangular patch 7 0 dB 9 7 1 dB L 0 328A W 0 219A Circular patch 7 1 dB 9 7 1 dB radius 0 185A Validation 2 Consider a five element array of isotropic elements with 0 4A spacing uniform amplitude and phased to scan at 60 Reference 3 gives the directivity as 7 0 dB PCAAD 6 0 gives 7 1 dB Validation 3 Consider a 10 element broadside array of isotropic elements with a spacing of 4 2 and a 26 dB Chebyshev amplitude distribution Element excitations from 2 are compared with results from PCAAD Element Reference 2 PCAAD 6 0 1 0 357 0 361 2 0 485 0 489 3 0 706 0 711 4 0 890 0 895 5 1 000 1 000 The excitations for elements 6 through 10 are symmetric with these The differences in the third decimal place in the above results can be attributed to round off error in the calculations in 2 as carrying through those calculations with five digit accuracy gives exact agreement with the results from PCAAD The directivity from PCAAD is 9
19. data file should be in ASCII form with each line consisting of an angle in degrees the pattern in dB and the phase in degrees at that angle The data must be in sequence in order of increasing angle These values are delimited with one or more spaces The PCAAD polar and rectangular pattern plotting routines can read these files with or without the phase column You can control whether the phase information is saved or not by using the check box on the Default Plot Types menu The pattern files written by PCAAD 6 0 are in this format and can be read by either the polar or the rectangular pattern plotting routines Up to two separate patterns can be plotted simultaneously either from data files or PCAAD antenna routines Each data set may be offset by a fixed amount through the Plot Options menu allowing patterns to be plotted in terms of absolute gain or to facilitate comparison of patterns normalized to different 13 values The default file extension for planar pattern data files is DAT Display boxes for each pattern are shown at the top left of the polar plotting window These indicate the name of the pattern either the filename or a description provided by the calling routine the main beam pointing angle the 3 dB beamwidth for the pattern and the offset of the data as set in the Plot Options window If the pattern does not have a well defined main beam or has more than one main beam e g grating lobes the beam po
20. efficiency is used The aperture is assumed to be located in an infinite ground plane polarized in the y direction and the radiation is assumed to be one sided This analysis assumes an equivalent magnetic current only and so does not include a 1 cos obliquity factor in contrast to the horn antenna analyses Begin by entering the frequency and the aperture diameter Then select the amplitude taper using the pull down menu You may choose to have either a uniform or a parabolic taper in the radial direction the parabolic taper has a maximum at the center of the aperture and is zero at the edge Click the Compute button to compute the patterns and directivity Pattern plots can be made in the E and H planes of the aperture or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation A circular planar array of diameter 10A with microstrip patches having lengths and widths of 0 34 element spacings of 0 5A and uniform amplitude and phase distributions yields a directivity of 30 1 dB using the PCAAD circular planar array routine The circular aperture routine for an aperture of 10A diameter and a uniform amplitude taper gives a directivity of 30 0 dB 63 E 4 E and H plane Sectoral Horn Antenna Analy
21. of 44 59 cm Reference 18 gives a directivity of 18 6 dB for this example PCAAD gives 18 5 dB 66 Validation 3 A standard gain horn has an E plane aperture dimension of 8 3 cm and H plane aperture dimension of 10 2 cm and E plane axial length of 22 7 cm and an H plane axial length of 24 1 cm At 24 GHz the measured gain is 24 7 dB PCAAD gives a directivity of 24 7 dB Comparisons with other standard gain horns typically are in agreement to within about 0 1 dB Validation 4 A corrugated pyramidal horn has E and H plane aperture dimensions of 24 2 cm and E and H plane axial lengths of 57 6 cm Reference 22 provides measured 3 dB beamwidths versus frequency along with independent calculations This data is compared with results from PCAAD below Frequency Measured Calculated PCAAD GHz Beamwidth 22 Beamwidth 22 Beamwidth 4 5 18 19 3 19 2 6 0 15 14 9 14 8 7 2 13 12 8 12 7 67 E 6 Diagonal Horn Analysis The diagonal horn antenna has a square aperture with the exciting electric field oriented along a diagonal axis The main beam of the diagonal horn has circular symmetry and the principal plane patterns have low sidelobes with no cross polarization Further discussion of the diagonal horn antenna can be found in 28 Begin by entering the frequency the square aperture dimension and the axial length of the horn Click the Compute button to compute the patterns and related ante
22. of the Compute button These values can be estimated by the routine by clicking the Compute button or you can enter your own values for center frequency frequency step size and the number of frequency points The geometry of the dipole may be viewed in three dimensions by clicking the Show Geometry button Upon clicking the Compute button the routine will compute the moment method solution for the dipole compute the RCS of the dipole over the specified frequency sweep and list the results in dB per square meter and in dB per square wavelength in a list box The scroll bar can be used to scroll through the data After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors Validation Consider a dipole 6 0 cm long with a radius of 0 002 cm At 3 GHz using three PWS expansion modes the RCS was computed at broadside and compared with results from 11 for two values of load impedance 24 Zi Reference 11 PCAAD 6 0 00 22 0 dBsm 21 9 dBsm 70Q 26 5 dBsm 26 7 dBsm Results were also compared with RCS data from 3 The angle dependence of the routine was checked by verifying that the RCS of a short dipole dropped off by 6 dB when both the incidence and s
23. or Windows Vista PCAAD 6 0 requires a 32 bit operating system and will not run under Windows 3 1 Best results will be obtained with a color monitor having a resolution of at least 800 x 600 Installation requires a CD ROM drive PCAAD 6 0 occupies less than 8 MB of disk space Since PCAAD 6 0 runs under Microsoft Windows operating systems we assume you are familiar with basic Windows usage Thus you should know how to run programs from Windows how to create and rearrange program shortcuts how to create copy and delete files and how to use Windows menus text boxes and control buttons It is also helpful to be aware of how to open close move and resize windows B Installing PCAAD 6 0 Installing PCAAD 6 0 on your system is easy Insert the distribution CD into your CD drive and execute the SETUP EXE program that is located on the CD Installation may require Administrator access depending on your operating system By default the setup program will install PCAAD 6 0 into a subdirectory called PCAAD6 in the Windows Program Files directory but a different directory may be specified if desired The setup program will decompress and install all necessary files and a PCAAD 6 0 entry will be created on your Start Menu and a PCAAD 6 0 icon will be installed on your desktop PCAAD uses a number of small bitmap files which are stored in the PCAAD6 BMP subdirectory PCAAD 6 0 can be started from the Start Menu or from the PCAAD 6 0 icon on
24. the Array Phase Distribution and the Array Element Selection These three windows are described in Section D 1 48 Validation 1 Consider a 2x2 broadside array of isotropic elements with A 2 spacings and uniform amplitude excitation An exact expression for the directivity of broadside planar arrays of isotropic sources is given in 7 This expression gives a directivity of 7 08 dB for this array PCAAD gives 7 1 dB This routine was also validated by checking several special cases of single elements and linear arrays with the linear array routine Planar array patterns were also checked for the correct scan angles and sidelobes Validation 2 Consider a 4x4 planar array of x polarized rectangular microstrip patches with a triangular grid of 60 a spacing in the x direction of 0 5774A and a spacing in the y direction of 0 54 The patch length and width are 0 3A PCAAD 6 0 gives the following results Quantity PCAAD 6 0 3 dB beamwidth in o 0 plane 21 7 3 dB beamwidth in o 45 plane 22 7 3 dB beamwidth in o 90 plane 25 1 Directivity 18 0 dB These results should be similar to those obtained with an array using a rectangular grid and filling the same aperture area For example a patch array with a rectangular grid having 8 elements in the x direction with a spacing of 0 289A 4x0 5774 8 and 4 elements in the y direction with a spacing of 0 5A yields a directivity of 18 1 dB 49 D 4 Uniform Circular Planar
25. the analysis routines A The Plot Menu The first five of the options on the Plot menu allow you to plot data from files using PCAAD s plotting routines Antenna patterns can be plotted in polar or rectangular form or in 3 D volumetric form Impedance data can be plotted on a Smith chart or on a VSWR Return Loss plot The Default Plot Types option is used to control the default plot type when patterns or impedances are plotted directly from PCAAD s antenna routines Default Plot Colors is used to set the preferred colors used in the pattern and impedance plots Exit is used to exit the program A 1 Polar Pattern Plot This routine plots up to two planar antenna radiation patterns in polar form It can be called directly from most of the PCAAD antenna routines to plot patterns or used independently from the Plot menu to plot patterns from a data file The routine also computes the main beam pointing angle the 3 dB beamwidth of the main beam and provides a movable angle cursor to read pattern values at any angle The Plot Options window allows control of various plot parameters such as the number of divisions scales plotting ranges offsets and colors The resulting plot can be printed on your printer or exported to another application using the Windows clipboard and the Copy Graph command from the Edit menu To read pattern data from a data file click the Read Data File button and use the file dialog box to specify a filename The
26. the list of excitations You also have the option of saving the amplitude distribution to a data file by clicking the Save Data button The Array Phase Distribution window allows you to choose the phase variation across the array from one of three options or to read phase data from a data file e Broadside Beam phase set to zero on each element e Specify Scan Angle progressive phase shift to steer beam to a specified scan angle e Specify Phase Shift progressive phase shift applied e Data File phase data is read from a specified data file 42 The Specify Scan Angle and Specify Phase Shift options require entry of the main beam scan angle or the interelement phase shift respectively Specifying the scan angle for a linear array requires only the elevation angle while the scan angle for a planar array requires both the elevation angle and the azimuth angle Once a phase distribution has been selected the routine will calculate the new set of excitation phases for the array elements and display them in the list box The scroll bar can be used to scroll through the list of excitation phases These quantities will change when the frequency or element spacing is changed from the linear array window Gaussian distributed zero mean errors can also be added to the phase distribution by entering a non zero value for the rms error standard deviation Entering a non zero value causes the phase excitation to be modified and updated in the list box
27. the x y plane if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The pattern is computed using the array factor of the array multiplied by the element factor Mutual coupling effects are not included in this routine Directivity is computed by numerical integration of the pattern which can be very time consuming for large arrays The maximum size of the array is limited to 200 elements in each dimension As indicated in the picture at the top left of the form the array is assumed to lie in the x y plane if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The angle of the grid can be adjusted to treat arrays having either a rectangular or a triangular grid The grid angle is 90 for a rectangular grid for an equilateral triangular grid the grid angle is 60 and the relation between the element spacings in the x and y directions is 3 d PE mS 2 x The pattern is computed using the array factor of the array multiplied by the element factor Mutual coupling is not included in this routine Directivity is computed by numerical integration of the pattern which can be very time consuming for large arrays The maximum size of the array is limited to 200 elements in each dimension Like the linear array routine this routine uses three additional windows to select the Array Amplitude Distribution
28. versus frequency It can be called directly from PCAAD routines that calculate impedance such as the wire antenna and microstrip element routines or it can be used independently from the Plot menu to plot impedance data from a file The resulting plot can be printed on your printer or exported to another application using the Windows clipboard and the Copy Graph command from the Edit menu Select either a VSWR or Return Loss plot by clicking the appropriate option button to the left of the plot Plot options such as interpolation and color of plotted data characteristic impedance and the range and number of divisions for the vertical and frequency scales can be set by clicking the Plot Options button When used with a data file the file should be in ASCII form with one line for 18 each data point The real part the imaginary part and the frequency up to five characters should be delimited with commas or spaces The impedance data is assumed to be in absolute ohms not normalized form This is the same format used by the Smith chart routine and the format that PCAAD uses when saving impedance data to a file A 6 Default Plot Types The default type of pattern plots polar rectangular or 3 D and impedance plots Smith chart or VSWR Return Loss are selected with this window You can select planar pattern cuts in polar or rectangular form or a three dimensional volumetric pattern plot Your selections on this window can be sa
29. your desktop The PCAAD 6 0 installation procedure also creates a subdirectory PCAAD6 SHORTCOURSE which contains PDF files for an introductory short course on antennas The course is arranged by Chapters 0 through 7 where Chapter 0 lists the contents and syllabus for the course Chapters through 7 provide a basic introduction to antenna theory and design and include examples review questions and problems The course concludes with the Antenna IQ test Answers to the test and all problems are given in the Answers pdf file There is also a short Glossary on commonly used terms related to antenna technology These files may be accessed from the PCAAD 60 Help menu or directly from the PCAAD6 SHORTCOURSE directory The Acrobat PDF reader is required to view the short course files To uninstall PCAAD 6 0 use the Add Remove Programs facility located in the Windows Control Panel This will properly remove the PCAAD 6 0 systems files from your computer and the registry Any data files that you created when using PCAAD 6 0 will have to be deleted separately C The PCAAD6 INI file PCAAD 6 0 uses a file called PCAAD6 INI located in the PCAAD 6 0 program directory to set some options and directory locations that are required for proper operation of PCAAD Generally you will not have to modify this file and like most INI files improper entries can cause errors when running PCAAD Here we describe the entries in the PCAAD6 INI file with their de
30. 13 E plane 3 dB beamwidth 100 103 H plane 3 dB beamwidth 80 81 84 G The Transmission Lines and Waveguides Menu This set of eight routines provide solutions for the analysis and design of several types of transmission lines and waveguides that are commonly used in microwave and antenna systems Included are analysis and design solutions for microstrip line and stripline and analysis solutions for covered microstrip line coaxial line rectangular waveguide circular waveguide and surface waves on a grounded dielectric substrate Also included is a routine that lists data for standard rectangular waveguide G 1 Microstrip Line Analysis and Design This routine is used to find the characteristic impedance of a microstrip transmission line given the substrate parameters and line width or to find the line width given the substrate iti ES i parameters and the characteristic impedance d Attenuation due to conductor and dielectric loss M can also be calculated if desired These solutions employ closed form quasi static formulas that generally give good results for most practical design problems as discussed in reference 10 First choose either the Compute Zo option or the Compute width option by clicking the appropriate button at the left side of the window This will change the input statements for the relevant data entry When computing characteristic impedance you will enter t
31. 3 11 C 1 Wire Dipole Antenna Analysis This routine computes the input impedance broadside gain and radiation pattern of a dipole antenna The feed point can be placed at the center of any expansion mode The solution uses the piecewise sinusoidal PWS Galerkin L moment method with the exact exponential integral expressions used for the impedance matrix elements as detailed in references 11 12 This method has proven to be the most accurate and efficient technique for solving thin wire antenna and scattering problems Begin by entering the dipole length the dipole radius the number of PWS expansion modes and the position of the feed generator The generator feed point must be located at the center of a PWS expansion mode If the dipole is center fed the number of expansion modes should be odd and the mode number of the generator should be the middle mode this mode number is automatically selected as the default mode number for the generator Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The resonant frequency of the dipole the frequency step size and the default number 7 of frequency points are displayed to the right of the
32. 35 dB cm 0 0135 dB cm 89 G 4 Coaxial Line Analysis This routine computes the characteristic impedance and attenuation due to dielectric loss and conductor loss for a coaxial line It also computes the cut off frequency of the TE waveguide mode of the coaxial line The formulas used in this routine are standard results as found in reference 10 Begin by entering the inner conductor radius the outer conductor radius and the dielectric constant Click the Compute Zo button and the routine will compute and print the characteristic impedance of the coaxial line and the approximate cut off frequency of the TE waveguide mode You can compute attenuation for the coaxial line by entering the frequency the loss tangent of the dielectric filling material and the conductivity of the coax conductors The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute Attenuation button and the attenuation due to dielectric loss conductor loss and the total attenuation will be printed in dB cm Validation Consider a copper coaxial line with an inner conductor radius of 0 5 mm an outer conductor radius of 1 5 mm a dielectric constant of 2 5 and a loss tangent of 0 01 operating at 10 GHz The formulas in 10 give the following results compared with PCAAD Quantity Reference 10 PCAAD 6 0 Charac
33. 9 5 450 76 j 6 9 5 758 9 6 600 78 j 11 9 4 80 12 9 3 The figure below show the principal plane patterns for the array at 300 MHz Figure 3 E plane black and H plane blue patterns of the LPDA array 37 C 9 General Wire Antenna Analysis This routine analyzes a general wire antenna geometry using a moment method solution that includes all mutual coupling terms An arbitrary number of bent wire segments can be specified with arbitrary positions and voltage generators and lumped loads can be specified at the terminals of any expansion mode The main limitation is that junctions between more than two wires are not allowed All wires must also have the same radius Wire currents are expanded using piecewise sinusoidal PWS modes as described in references 11 12 The wire geometry is specified by defining a set of x y z coordinates to define the terminals of each PWS expansion mode on the wire structure The geometry is specified in an ASCII data file extension ANT with the following format note the format of this data file differs from that used in PCAAD 4 0 FREQ A frequency GHz wire radius cm NP number of points on the wire structure xX Yy Z coordinates in cm of each point on the wire geometry one row for each point NM number of PWS expansion modes Tl 12 T2 indices of the three coordinates that define each PWS mode NPORTS number of generator and or load ports PMODE VGR
34. 9 dB 19 4 dB E plane pattern at 17 5 10 dB 9 9 dB H plane pattern at 17 5 10 dB 10 3 dB 70 E 8 Approximate Parabolic Reflector Analysis This routine analyzes the performance of a prime focus parabolic reflector antenna under the assumption that the feed antenna has a rotationally symmetric power pattern that can be approximated as cos In this case simple but exact expressions can be obtained for the spillover and taper efficiencies as discussed in reference 2 The effect of surface roughness can also be included Begin by entering the frequency the D ratio the dish diameter and the rms surface roughness The surface roughness dimension has a default value of zero Next specify the feed pattern in one of three forms enter either the 3 dB beamwidth the 10 dB beamwidth or the actual value ofn 2 4 6 or 8 for a pattern of the form cos 8 If you specify a beamwidth the routine will calculate the closest value of n that approximates this beamwidth and will display the value of n that it will use The routine then computes the spillover taper roughness and total aperture efficiencies then computes the directivity of the antenna The 3 dB beamwidth is also calculated from the directivity Validation Consider a parabolic reflector with a dish diameter of 1000 cm an D ratio of 0 5 a feed pattern with n 2 and no surface roughness operating at 3 GHz This example is considered in 2
35. 90 40 9 j 9 0 Q 40 1 j 8 9 Q 150 69 3 j 39 Q 69 1 j 38 9 Q 180 73 1 j 42 Q 73 1 j 42 2 Q Validation 2 Consider a V dipole with arm lengths of 1 5 and radius 0 001 From 2 the internal angle that results in maximum directivity is 82 5 The resulting directivity from 2 is approximately 7 5 dB Using 11 expansion modes PCAAD gives a value of 7 8 dB 27 C 4 Wire Loop Antenna Analysis z This routine computes the input impedance gain and radiation pattern of a wire loop antenna The solution uses the piecewise sinusoidal expansion PWS Galerkin method with the exact exponential integral expressions used for the impedance matrix elements as detailed in references 11 12 This method has proven to be the most accurate and efficient technique for solving thin wire antenna and scattering problems Begin by entering the radius of the loop the wire radius and the number of PWS expansion modes Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The resonant frequency of the loop the frequency step size and the default number 7 of frequency points are displayed to the right of the Compute button These values can be
36. AD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors 30 Validation Consider a Yagi array with the following specifications Reflector length 47 9 cm Fed element length 45 3 cm Director length 1 45 1 cm Spacing between reflector and feed 25 0 cm Spacing between feed and director 25 0 cm Dipole radius 0 25 cm Frequency 0 30 GHz This geometry is analyzed in 3 although the number of expansion modes is not stated Running PCAAD 6 0 with 9 PWS modes per element 27 modes total gives the following results Quantity Reference 3 PCAAD 6 0 Input impedance 224 j15Q 22 14 Gain 9 4 dB 9 5 dB Front to back ratio 5 6 dB 5 7 dB The principal plane patterns of the Yagi array are shown below Figure 1 E plane black and H plane blue patterns of the Yagi array 31 C 6 Finite Wire Dipole Array Analysis This routine analyzes a finite planar wire dipole array using a moment method solution that includes all mutual coupling terms Dipole currents are expanded using piecewise sinusoidal PWS modes as described in references 11 12 The routine computes input impedance at each dipole array gain and principle plane patterns for the array The number and spacing of dipoles in each plane of the array is variable but all dipoles are assumed t
37. Analysis for Printed Slot and Slot Coupled Microstrip Antennas IEEE Trans Antennas and Propagation Vol AP 34 pp 1439 1446 December 1986 17 D M Pozar Rigorous Closed form Expressions for the Surface Wave Loss of Printed Antennas Electronics Letters vol 26 pp 954 956 June 1990 18 E Jull Aperture Antennas and Diffraction Theory Peter Peregrinus London 1981 19 A D Bresler A New Algorithm for Calculating the Current Distributions of Dolph Chebyshev Arrays IEEE Trans Antennas and Propagation vol AP 28 pp 951 952 November 1980 20 A T Villeneuve Taylor Patterns for Discrete Arrays IEEE Trans Antennas and Propagation vol AP 32 pp 1089 1093 October 1984 21 S M Duffy and M A Gouker A Modified Transmission Line Model for Cavity Backed Microstrip Antennas 1996 IEEE Antennas and Propagation Symposium Digest pp 196 199 July 1996 22 E A Swanson P Elliot and D M Pozar Design of a Broadband Corrugated Hom Antenna Microwave Remote Sensing Laboratory Report MIRSL 82 1 University of Massachusetts 1982 23 N K Das and D M Pozar Full wave Spectral Domain Computation of Material Radiation and Guided Wave Losses in Infinite Multilayered Printed Transmission Lines IEEE Trans Microwave Theory and Techniques pp 54 63 January 1991 24 A Simmons Polarization Mismatch Loss IEEE Antennas and Propagation Newsletter pp 15 16 August 1984 25 D M
38. Fed Patch Analysis 4 Rectangular Proximity Fed Patch Analysis 5 Rectangular Aperture Coupled Patch Analysis 6 Circular Probe Fed Patch Analysis G The Transmission Lines and Waveguides Menu Microstrip Line Analysis and Design Covered Microstrip Line Analysis Stripline Analysis and Design Coaxial Line Analysis Rectangular Waveguide Analysis Standard Rectangular Waveguide Data Circular Waveguide Analysis Surface Wave Analysis AADNA HWY 30 32 35 36 38 41 41 46 48 50 51 53 54 56 58 60 61 62 63 64 66 68 69 71 72 74 74 75 77 79 81 83 85 85 87 88 90 91 92 93 94 H The Miscellaneous Menu 95 1 Communication Link Loss 95 2 Polarization Mismatch Between Two Antennas 96 3 Atmospheric and Rain Attenuation 97 4 Axial Ratio versus Amplitude and Phase Error 98 5 Antenna Noise Temperature 99 6 Microwave and Antenna Calculator 100 V References 101 I Introduction to PCAAD 6 0 PCAAD 6 0 is a Windows compatible software package that contains over 45 separate routines for the analysis and design of wire antennas array antennas aperture antennas microstrip antennas and transmission lines and waveguides These routines are integrated into a menu driven user friendly software package that allows you to quickly evaluate impedance and pattern characteristics for a large variety of antenna geometries Some of the main features of PCAAD 6 0 include the foll
39. PCAAD 6 0 Personal Computer Aided Antenna Design Version 6 0 David M Pozar Antenna Design Associates Inc Leverett MA 01054 On the cover 3D pattern plot for a circular array of radius 1 4A isotropic elements spacing of 0 4 Copyright 2007 David M Pozar Antenna Design Associates Inc 55 Teawaddle Hill Road Leverett MA 01054 USA All rights reserved Printed and bound in the United States of America No part of this book may be reproduced or utilized in any form or by any means electronic or mechanical including photocopying recording or by any information storage and retrieval system without permission in writing from the author I Introduction to PCAAD 6 0 4 A What s New in PCAAD 6 0 4 B Disclaimer 5 Il Getting Started With PCAAD 6 0 6 A System Requirements 6 B Installing PCAAD 6 0 6 C The PCAAD6 INI file 7 IHI Using PCAAD 6 0 General Instructions 9 A Organization of PCAAD 6 0 9 B Entering Data and Running the Routines 11 C Pattern Calculation and Plotting 11 D Saving Pattern Data 11 E Impedance Calculation and Plotting 12 F Help 12 IV Using PCAAD 6 0 Instructions and Examples 13 A The Plot Menu 13 1 Polar Pattern Plot 13 2 Rectangular Pattern Plot 15 3 3 D Pattern Plot 16 4 Smith Chart Plot 16 5 VSWR Return Loss Plot 18 6 Default Plot Types 19 7 Default Plot Colors 19 8 Exit 19 B The Edit Menu 20 1 Copy Window 20 2 Copy Graph 20 3 Copy Text 20
40. Pozar and S Targonski Axial Ratio of Circularly Polarized Antennas with Amplitude and Phase Errors IEEE Antennas and Propagation Magazine pp 45 46 October 1990 26 R J Mailloux Phased Array Antenna Handbook Artech House 1994 27 L Blake Antenna Noise Temperature IEEE Antennas and Propagation 102 Newsletter pp 8 9 December 1984 28 A W Love The Diagonal Horn Antenna Microwave Journal pp 117 122 March 1962 29 D L Waidelich The Phase Center of Aperture Antennas IEEE Trans Antennas and Propagation vol AP 28 pp 263 264 March 1980 103
41. The phase excitation data can also be saved in an ASCII data file by clicking the Save Data button The Array Element Selection window allows you to select from one of five different element types and to select the polarization of the element when possible e Isotropic ideal isotropic point source elements e Wire Dipole thin wire dipole with or without a ground plane e Rectangular Waveguide rectangular waveguide aperture in a ground plane e Circular Waveguide circular waveguide aperture in a ground plane e Rectangular Microstrip Patch rectangular microstrip patch elements e Circular Microstrip Patch circular microstrip patch elements Select the array element type by clicking the appropriate button All but the isotropic element option requires entry of the element dimensions and polarization The waveguide elements and the microstrip patch elements may be polarized in either the x direction the plane of the array or in the y direction orthogonal to the plane of the array The wire dipole may be polarized in the x y or z vertical direction and may include a ground plane spaced a specified distance below the element Specify no ground plane by setting the ground plane spacing to zero The rectangular waveguide is assumed to have a TEi mode distribution while the circular waveguide is assumed to have a TE mode distribution The patch elements are assumed to be operating in the dominant resonant mode Validation 1 We first
42. a At this point you can plot the impedance locus versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation Consider a rectangular microstrip line fed microstrip antenna with a patch length of 3 315 cm a patch width of 3 317 cm a dielectric constant of 2 2 a substrate 77 thickness of 0 079 cm a loss tangent of 0 001 and a feed line width of 0 47 cm Measured results from 9 are compared with PCAAD Quantity Measured 9 PCAAD 6 0 Resonant frequency 3 00 GHz 3 01 GHz Resonant resistance 278 Q 241 Q Bandwidth 1 1 1 1 78 F 4 Rectangular Proximity Coupled Patch Analysis This routine analyzes a rectangular proximity coupled microstrip antenna using a transmission line model discussed in references 9 16 21 The patch is treated as a transmission line with equivalent end admittances to account for radiation and length extensions are used to account for fringing fields at the radiating edges The reciprocity method is used to compute the coupling term between the feed line and the edge of the patch and the t
43. ach propagating surface wave mode The routine also computes and prints an approximate value for the radiation efficiency of a printed antenna on this substrate This efficiency is based on power lost to surface waves and is meaningful because it has been shown that this type of radiation efficiency is fairly independent of the type or size of the actual radiating element depending primarily on the substrate dielectric constant and thickness as discussed in reference 17 Validation Consider the surface wave for a substrate with a dielectric constant of 2 55 and a thickness of 0 19 cm operating at 30 GHz This case occurs in 13 where the normalized propagation constant is given as ko 1 283 PCAAD gives a value of 1 28249 94 H The Miscellaneous Menu This set of six routines provide several solutions and data for a variety of topics related to antennas and applications Included are routines for calculating communication link loss the polarization mismatch between two antennas the degradation in axial ratio caused by amplitude and phase errors graphs for atmospheric attenuation and antenna temperature and a calculator for useful microwave and antenna functions H 1 Communication Link Loss This routine computes the link loss for a radio communications link using the Friis formula 2 3 10 Gt Gr Enter the gains of the transmit and receive C gt antennas the range between transmitter and R
44. additional windows to select the array amplitude distribution the array phase distribution and the array element type These windows are accessed by clicking the small Select button to the right of the appropriate text box for amplitude phase and element type Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Note that E plane H plane patterns are not available when the array elements are vertical monopoles Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The Array Amplitude Distribution window allows you to choose from four commonly used amplitude distributions or to read amplitude data from a data file 41 e Uniform uniform amplitude distribution e Chebyshev Chebyshev amplitude taper for a specified sidelobe level e Taylor Taylor amplitude taper for a specified sidelobe level and n bar parameter e Cosine on a pedestal cosine on a pedestal distribution of the form C 1 C cos zx L e Data File amplitude data is read from a specified data file Select one of the five amplitude distribution options by clicking the appropriate button For the Chebyshev distribution the desired sidelobe level must also be entered as a positive value in dB The Chebyshev coefficients are computed using the hi
45. alue from a data box to the Windows clipboard first select the data using the mouse Then click Copy Text from the Edit menu This function can also be accomplished by pressing Ctrl C after selecting the desired data or by right clicking the mouse and selecting Copy B 4 Paste Text To copy a value from the Windows clipboard to a data box in PCAAD click on the desired data box then click Paste Text from the Edit menu This function can also be accomplished by pressing Ctrl V or by right clicking the mouse and selecting Paste B 5 Edit file Click the Edit File option from the Edit menu to invoke the Windows system text editor typically Notepad This allows you to easily view or edit data files when using PCAAD 6 0 The location of the system editor is specified in the PCAADS INI file as described in Section II C 20 B 6 Print Window This option is used to print the current active analysis or plotting routine window This function is useful for obtaining a hard copy of the complete set of input output data associated with a PCAAD 6 0 routine Input data output data and graphics are printed 21 C The Wire Antennas Menu These nine routines involve the analysis and design of various wire antennas Wire dipoles loops Yagi Uda arrays planar dipole arrays log periodic dipole arrays and more general wire antenna geometries are modeled using a standard thin wire Galerkin moment method solution with piecewise sinusoidal modes
46. and compared with PCAAD below Quantity Reference 2 PCAAD 5 0 Spillover efficiency 0 784 0 784 Taper efficiency 0 957 0 957 Aperture efficiency 0 750 0 751 Directivity 48 7 dB 48 7 dB 71 E 9 Parabolic Reflector Pattern Analysis This routine computes the patterns of a prime focus parabolic reflector antenna by numerical aperture integration as outlined in references 2 3 The feed is specified with two data files for the E and H plane patterns these may be generated through other PCAAD antenna routines The aperture efficiency and directivity are also computed by numerical integration The effect of surface roughness can also be included Begin by entering the frequency the f D ratio the dish diameter and the rms surface roughness The surface roughness dimension has a default value of zero Next select the feed pattern files using the file dialog boxes The feed pattern data must be in the format of angle in degrees pattern in dB with an angle range that extends at least from 90 to 90 The step size of the feed pattern data file is arbitrary numerical interpolation is used when necessary Pattern files generated by other PCAAD routines follow this format allowing other PCAAD routines to be used to generate feed patterns for direct use in this routine For example a horn antenna module can be used to generate a feed pattern file which can then be used in this routine to find the secondary patterns o
47. and print the characteristic impedance and the cut off frequency of the parallel plate waveguide mode When calculating line width for stripline design you will enter the characteristic impedance the dielectric constant the ground plane spacing and the strip thickness Click the Compute width button to compute and print the required line width and the cut off frequency of the parallel plate waveguide mode You may compute the attenuation for the line for either the line analysis or the line design case Enter the frequency the loss tangent of the dielectric filling material and the conductivity of the stripline conductors The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute Attenuation button and the attenuation due to dielectric loss conductor loss and the total attenuation will be printed in dB cm Validation Consider the design of a 50 Q stripline at 10 GHz on a substrate with a dielectric constant of 2 2 and a ground plane spacing of 0 32 cm The thickness of the strip is 0 001 cm the conductors are copper and the dielectric loss tangent is 0 001 This example corresponds to Example 3 5 in 10 and results from 10 are compared with PCAAD below 88 Quantity Reference 10 PCAAD 6 0 Line width 0 266 cm 0 262 cm Conductor attenuation 0 0106 dB cm 0 0105 dB cm Dielectric attenuation 0 01
48. ange the resulting axial ratio A graph illustrating constant axial ratio contours versus amplitude and phase errors is also shown this can be useful for estimating the amplitude and phase accuracies required for a given axial ratio Validation For two orthogonal linearly polarized antennas having excitations with zero phase error and 3 dB amplitude error PCAAD gives an axial ratio of 3 dB in agreement with the graph and with the results in 25 For the case of zero amplitude error and a phase error of 30 PCAAD gives an axial ratio of 4 8 dB in agreement with the graph and with the results in 25 98 H 5 Antenna Noise Temperature taken from 27 Validation This routine presents a graph of the background noise temperature for an ideal lossless antenna versus frequency and elevation angle elevation angle is measured from the horizon so 90 is overhead The antenna is assumed to have a narrow pencil beam with no sidelobes pointed toward the earth Results are given for various elevation angles measured from the horizon The minimum and maximum noise temperatures are also shown This data is At a frequency of 2 GHz a narrow beam antenna pointed directly overhead will see an apparent noise temperature of about 9 K An antenna with a more omnidirectional pattern will see a noise temperature as high as 100 K 99 H 6 Microwave and Antenna Calculator This routine provides a calculator funct
49. array for a specified bandwidth and gain based on the formulas given in reference 2 with corrections from reference 8 The routine computes the necessary number of dipoles in the array and the spacings lengths and radii for each element First enter the lower and upper frequencies of the desired operating band Then enter the desired gain between 7 and 11 dB and the radius of the largest dipole The routine prints out the log periodic array scale factors and q followed by a list of the spacing length and radius for each element in the array The scroll bar in the list box can be used to scroll through the elements Spacings are measured from the largest dipole the last spacing is not Validation Consider an LPDA design with a lower frequency of 54 MHz an upper frequency of 216 MHz a directivity of 7 5 dB and a largest dipole radius of 1 cm This case is given in 1 with the following results Quantity Reference 1 PCAAD 6 0 oO 0 147 0 147 T 0 822 0 822 First dipole length 264 8 cm 264 8 cm Spacing to second dipole 77 8 cm 77 8 cm Third dipole radius 0 64 cm 0 64 cm Last dipole length 55 2 cm 55 2 cm 35 C 8 Log Periodic Dipole Array Analysis This routine performs a complete analysis of a log periodic dipole array using a moment method solution that includes all mutual coupling terms Dipole currents are expanded using piecewise sinusoidal PWS modes as described in references 11 12 The arr
50. ation 1 Consider an E plane sectoral horn at 3 GHz with an E plane aperture dimension of 27 5 cm an H plane aperture dimension of 5 cm and an axial length of 60 cm Results for this example can be found in 2 and are compared with results from PCAAD below Quantity Reference 2 PCAAD 6 0 Max phase error 56 7 56 7 Directivity 11 1 dB 11 1 dB H plane pattern at 60 5 dB approx 4 1 dB Validation 2 Consider an H plane sectoral horn at 3 GHz with an E plane aperture dimension of 2 5 cm an H plane aperture dimension of 55 cm and an axial length of 60 cm Results for this example can be found in 2 and are compared with results from PCAAD below 64 Quantity Reference 2 PCAAD 6 0 Max phase error 226 9 226 9 Directivity 8 76 dB 8 8 dB E plane pattern at 60 3 5 dB approx 3 2 dB H plane pattern at 30 15 dB approx 15 7 dB 65 E 5 Pyramidal and Corrugated Pyramidal Horn Analysis These two routines compute the patterns and directivity of pyramidal and corrugated pyramidal horn antennas using closed form expressions from reference 2 For horns with b small apertures accuracy is improved by E computing the directivity by numerical BE integration of the pattern The choice of pyramidal or corrugated pyramidal horn is made a from the Aperture antenna menu The phase center for both principal planes is also computed L Begin by entering the frequency the E and H plane apert
51. ay is fed with a transmission line having alternating terminals and analyzed using port admittance matrices as described in reference 3 The routine computes the input impedance at the feed port the array directivity and gain and the patterns for the array As shown in the graphic the dipoles are all parallel to the x axis with the main beam in the z direction The feed is assumed to be at the terminals of the smallest dipole and a matched load is assumed to be located at the terminals of the largest dipole The dimensions and spacings can be manually entered for each dipole or you can enter the O and T parameters for the array and let the routine calculate all necessary dimensions The geometry of the LPDA can be viewed in three dimensions by clicking the Show Geometry button Begin by entering the frequency the feed line characteristic impedance the number of dipoles in the array and the number of expansion modes to be used on each dipole this value may need to be increased for frequencies at the high end of the operating range At this point you can click the Get Data button to enter the O and T parameters of the LPDA array along with the length and radius of the first longest dipole in the array The routine will then compute all necessary dimensions and spacings for the array and automatically enter these values upon clicking the OK button into the scroll boxes Alternatively you can manually enter the length spacing and
52. c rod antennas electrically long slot antennas and leaky wave antennas The phase constant and attenuation constant can be 0 specified and the antenna can be fed at either the end or at the center of the line A sin 8 element pattern factor can also be included if desired Patterns are computed using the closed form expressions found in reference 2 Directivity is also calculated using closed form expressions After entering the frequency line source length and phase and attenuation constants click the Compute button to calculate the pattern and directivity Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation Consider a traveling wave end fed wire antenna with a length of 5A The phase constant will be close to 360 A and the attenuation may be neglected Since this is a wire antenna a sin factor should be used Reference 2 gives a beam maximum angle of 22 0 from the axis of the wire in agreement with the pattern calculated by PCAAD The free space directivity from 2 is 10 7 dB also in agreement with PCAAD 61 E 2 Rectangular Aperture Antenna Analysis This routine computes the patterns and directivity of a rectang
53. cattering angles were changed to 45 25 C 3 V Dipole Antenna Analysis This routine computes the input impedance gain and radiation pattern of a V dipole antenna The internal angle of the V dipole is variable an angle of 180 corresponds to a straight dipole The feed point is at the apex of the wire arms The solution uses the piecewise yf sinusoidal expansion PWS Galerkin method with the exact exponential integral expressions used for the impedance matrix elements as detailed in references 11 12 This method has proven to be the most accurate and efficient technique for solving thin wire antenna and scattering problems Begin by entering the dipole arm length the dipole radius the number of PWS expansion modes and the internal angle of the dipole between 2 and 180 Because of symmetry the number of PWS expansion modes must be odd Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The resonant frequency of the V dipole the frequency step size and the default number 7 of frequency points are displayed to the right of the Compute button These values can be estimated by the routine by clicking the Compute button or
54. ce of the antenna over this frequency sweep and display the results in the list box If necessary use the scroll bar at the right of the box to scroll through the list of impedances The routine also computes the approximate bandwidth the radiation efficiency the front to back ratio and the directivity of the antenna At this point you can plot the impedance locus versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button 81 Validation Consider a rectangular aperture coupled microstrip antenna with the following parameters Antenna substrate dielectric constant 2 54 Antenna substrate thickness 0 16 cm Patch length 4 0 cm Patch width 3 0 cm Feed substrate dielectric constant 2 54 Feed substrate thickness 0 16 cm Slot length 1 12 cm Slot width 0 155 cm Feed line width 0 442 cm Stub length 2 0 cm Calculated data using the model of 16 are compared with PCAAD at f 2 217 GHz Quantity Reference 16 PCAAD 6 0 Input impedance 65 17 Q 64 j 0 8 Q Gain efficiency x directivity 6 2 dB 6 1 dB Front to back ratio 23 dB 25 dB 82
55. d Data File button and use the file dialog box to specify a filename The data file should be in ASCII form with each line consisting of an angle in degrees the pattern in dB and the phase in degrees at that angle The data must be in sequence in order of increasing angle These values are delimited with one or more spaces The PCAAD polar and rectangular pattern plotting routines can read these files with or without the phase column You can control whether the phase information is saved or not by using the check box on the Default Plot Types menu The pattern files written by PCAAD 6 0 are in this format and can be read by either the polar or the rectangular pattern plotting routines Up to two separate patterns can be plotted simultaneously either from data files or PCAAD antenna routines Each data set may be offset by a fixed amount through the Plot Options menu allowing patterns to be plotted in terms of absolute gain or to facilitate comparison of patterns normalized to different values The default file extension for planar pattern data files is DAT Display boxes for each pattern are shown at the top left of the rectangular plotting window These indicate the name of the pattern either the filename or a description provided by the calling routine the main beam pointing angle the 3 dB beamwidth for the pattern and the offset of the data as set in the Plot Options window If the pattern does not have a well defined main
56. e we obtain the following results Theta Zin Reference 13 Zin PCAAD 6 0 0 74 8 j 2 7 Q 74 8 j 2 8 Q 30 73 3 j 37 3 Q 73 4 j 37 3 Q 60 40 7 1 9Q 40 7 2 0Q 90 0 10 j 55 7 Q 0 10 j 55 7 Q 53 D 7 Woodward Lawson Linear Array Pattern Synthesis This routine can be used to synthesize the Z pattern of a uniform linear array using the Woodward Lawson method 2 3 You can specify array size element spacing and y frequency The pattern to be synthesized is specified in a scroll box at discrete pattern angles generated by the program The amplitude and phase excitation for each element are computed and listed in a scroll box The array elements are assumed to be isotropic sources with polarization along the x axis Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The pattern is computed using the array factor of the array mutual coupling effects are not included in this routine The pattern calculated in this routine is not normalized other PCAAD routines normalize the maximum pattern value to 0 dB in order to compare with the specified pattern values For this reason it may be necessary to adjust the maximum va
57. e Plot Circles button to draw the grating lobe circles the plot will automatically be updated if new data is entered or if the zoom scroll bar is used By default the routine plots a segment of the u sin cos v sin sin plane from 3 lt u lt 3 and 3 lt v lt 3 The zoom scroll bar near the top of the window can be used to adjust this range The visible space region of the grating lobe diagram occurs for u v lt 1 and is colored in light gray on the plot The grating lobe circles are drawn in blue and the surface wave circles are drawn as red circles Moving the mouse cursor through the visible space region of the diagram will cause the readout box near the middle of the window to give a display of the cursor position in u v space as well as the corresponding theta phi scan angle In this way you can easily determine the scan angle at which a grating lobe enters visible space or the angle at which a scan blindness will occur More accuracy can be obtained by zooming in on the visible space region by using the zoom scroll bar 56 Validation Consider an example from 13 for an array of printed dipoles with E and H plane spacings of 2 on a dielectric substrate with 12 8 and a thickness of 0 06A The array grid is rectangular The PCAAD 6 0 Surface Waves routine gives a normalized surface wave propagation constant of 1 285816 Plotting the grating lobe diagram shows that no grating lobes will be present in visible s
58. e parameter and run a new solution Most routines have error checking of input data but the software is not completely foolproof B Entering Data and Running the Routines Numerical values are entered in PCAAD 6 0 using text boxes When a routine starts a flashing cursor bar will appear in the text box for the first data entry item Type in the numerical value and press Enter on the keyboard to move to the next entry You can also use the Tab key or the mouse to move to the next data entry Error checking is performed for most data entries generally after the Compute button is pressed If a value is found to be in error a small error message box is displayed Click the OK button on this box and focus will return to the data item that was found to be in error After you have computed a solution you can change one or more problem parameters by simply entering new values for those items without having to re enter all other parameters C Pattern Calculation and Plotting Many routines involve the calculation of far field radiation patterns These may be plotted as planar pattern cuts on a polar plot or a rectangular plot or as a 3 D volumetric plot The type of plot desired for a particular routine is specified by clicking the Pattern Type Select button Elevation plane patterns can be plotted at a specified azimuthal angle for E theta E phi or Co pol X pol patterns using Ludwig s third definition or E plane H plane patterns can be s
59. edance from 11 is compared with results from PCAAD 6 0 for various loop radii and expansion modes Note that using four expansion modes corresponds to a square loop while eight modes corresponds to an octagonal loop etc Loop PWS Zin Zin Radius Modes Reference 11 PCAAD 6 0 0 0707 A 4 44 8 j 1589 Q 44 8 j 1589 Q 0 1592 4 92 4 j 300 9 Q 92 4 j 300 9 Q 0 1592 8 109 7 j 149 3 Q 109 7 j 149 3 Q 0 1592 16 116 0 j 109 1 Q 116 0 j 109 1 Q 0 1592 64 117 5 j 95 Q 117 5 j 95 4 Q The directivity of a loop having a circumference of 1 radius 0 1592 is about 3 4 dB 2 PCAAD 6 0 gives a value of 3 3 3 5 dB depending on the number of expansion modes used 29 C 5 Yagi Dipole Array Analysis This routine analyzes a Yagi Uda dipole array using a moment method solution that includes all mutual coupling terms Dipole currents are expanded using piecewise sinusoidal PWS modes as described in references 11 12 The routine computes input impedance gain front to back ratio and patterns for the array The array is assumed to have one reflector element one driven dipole element and an arbitrary n number of director elements The length and spacing for each element is variable but the radius is assumed to be the same for all elements Begin by entering the frequency the dipole radius the number of PWS modes on each dipole and the number of director elements Next specify the lengths
60. elected Plotting parameters such as azimuth angle and step sizes are also specified with this window Default values can be set with the Plot Default Types option from the Plot menu Pattern plots can be invoked directly from a PCAAD antenna analysis routine or patterns can be plotted from data files through the Plot menu Up to two separate patterns can be plotted on the polar or rectangular plots but only one pattern can be plotted as a 3 D plot Plots may be printed click the Print Plot button in the plotting window or copied to the Windows clipboard for use in other applications use Copy Graph from Plot on the main menu bar D Saving Pattern Data Routines that provide far field radiation patterns also allow the option of saving pattern data planar or 3D to a file with the Save Patterns button PCAAD 6 0 now allows saving of far field phase data in addition to the pattern amplitude for planar patterns Phase data can be useful when using PCAAD results with other programs such as characterizing a feed for reflector antenna analysis Planar pattern data is saved as an ASCII text file with one row for each angle The format is pattern angle in degrees pattern amplitude in dB and pattern 11 phase in degrees These values are delimited with one or more spaces The PCAAD polar and rectangular pattern plotting routines can read these files with or without the phase column You can control whether the phase information is saved or
61. ents This routine uses two additional windows to select the array amplitude distribution and the array phase distribution The available amplitude and phase options are the same as those for the linear array module described in Section D 1 and are accessed by clicking the small Select button to the right of the appropriate text box for amplitude and phase The selected amplitude and phase distributions can each be modified with gaussian distributed random errors and can be saved as data files The element pattern file is selected with a file dialog box The element pattern data is assumed to be in the format of angle in degrees pattern in dB with an angle range from 90 to 90 The step size of the element data file is arbitrary numerical interpolation is used when necessary Pattern files generated by other PCAAD routines follow this format allowing other PCAAD routines to be used to generate element patterns for direct use in this routine For example a horn antenna module can be used to generate a pattern file which can then be used in this routine to find the pattern of an array of horns 46 Validation Consider an H plane broadside array of 8 half wave dipoles in free space having a spacing of 0 6A and a uniform amplitude distribution The pattern can be calculated using the linear array analysis routine which gives a 3 dB beamwidth of 10 6 This same array can also be considered as a 4 element array where each element
62. error term The phase center for both principal planes is also computed Begin by entering the frequency the aperture radius and the axial length of the horn This length is the distance from the imaginary apex of the horn to the mouth of the horn not the slant length Click the Compute button to compute the patterns and related antenna parameters The routine prints out the maximum phase error at the edge of the aperture relative to the center of the aperture and the directivity of the horn Pattern plots can be made in the E and H planes of the horn or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation 1 Consider a conical horn at 5 GHz with an aperture radius of 12 cm and an axial length of 48 6 cm Results from reference 5 are compared with PCAAD Quantity Reference 5 PCAAD 6 0 Max phase error 86 4 88 9 Directivity 20 4 dB 20 3 dB E plane pattern at 20 13 4 dB 12 9 dB H plane pattern at 20 15 0 dB 14 8 dB Validation 2 Consider a corrugated conical horn at 5 GHz with an aperture radius of 12 cm and an axial length of 48 6 cm Results from reference 5 are compared with PCAAD 69 Quantity Reference 5 PCAAD 6 0 Max phase error 86 4 88 9 Directivity 19
63. es with one line for each element The amplitude data is in absolute voltage or current form not in dB The routine uses an additional window to select the array element type accessed by clicking the small Select button to the right of the text box Validation The 4x4 patch array with a triangular grid that was treated in Validation 2 of Section D 3 was used here as well The data file listing the element coordinates and excitations for this array is listed below this file ARRAY4X4 DAT is supplied with PCAAD 6 0 Q 0 0 1 0 0 0 0 5774 0 0 1 0 0 0 1 154 0 0 1 0 0 0 1 732 0 0 1 0 0 0 0 2887 0 5 1 0 0 0 0 8661 0 5 1 0 0 0 51 1 444 0 5 1 0 0 0 2 0209 0 5 1 0 0 0 0 1 0 1 0 0 0 0 5774 1 0 1 0 0 0 1 154 1 0 1 0 0 0 TedS2 180 d0 0 0 0 2887 1 5 1 0 0 0 0 8661 1 5 1 0 0 0 1 444 1 5 1 0 0 0 2 0209 1 5 1 0 0 0 Results from this routine are in agreement with those obtained in Section D 3 52 D 6 Infinite Printed Dipole Array Analysis Y This routine computes the input impedance of an infinite array of dipole antennas printed on a grounded dielectric substrate using the full wave solution described in reference 13 It x uses the exact Green s function for the dielectric substrate and includes all mutual coupling o_o effects It can be used to treat dipoles in free e ee eee le ee ee eee space above a ground plane by using a substrate dielectric constant of 1 0 The number of piecewise
64. estimated by the routine by clicking the Compute button or you can enter your own values for center frequency frequency step size and the number of frequency points The geometry of the loop antenna may be viewed in three dimensions by clicking the Show Geometry button Upon clicking the Compute button the routine will compute the moment method solution for the loop and list the input impedance versus frequency in the list box The scroll bar can be used to scroll through the data The gain of the loop at its beam maximum is computed at the center frequency of the frequency sweep note that electrically small loops have a pattern null on axis while larger loops have a beam maximum on the axis of the loop At this point you can plot the impedance characteristics versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file The specified patterns are also calculated at the center frequency and may be plotted using the Plot Patterns button or saved to data files After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors 28 Validation Consider a wire loop antenna with a wire radius of 0 001A The calculated input imp
65. f the reflector Only the feed pattern amplitude is used The feed is assumed to be linearly polarized at 0 0 Select the pattern type and parameters with the Pattern Type Select button Pattern plots can be made in the E and H planes of the reflector or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle 3 D volumetric patterns are not available because the beamwidth of most reflectors is too narrow to be plotted in volumetric form Since most reflector antennas have narrow beamwidths the elevation step size should be small typically between 0 01 degrees and 0 1 degrees Also specify the maximum angular range of the elevation pattern plot Because of the narrow beamwidth of most reflector antennas the maximum angular range of the pattern calculation usually does not need to exceed a few degrees Since numerical aperture integration can be time consuming for an electrically large antenna computer time may be excessive if the maximum angular range is too large or the step size is too small Validation 1 Consider a reflector antenna with a diameter of 100A D 0 5 and a feed having a power pattern of cos in both planes This pattern can be obtained as the E plane pattern of a short dipole along the x axis as computed using the linear array routine with one dipole element Exact results can be obtained from the previous reflector 72 analysis routine with n 2 The following results are obtained
66. fault values PCAAD6 FileDir C Windows Program path to user file directory SystemEditor C WINDOWS NOTEPAD EXE path to system text editor Bitmaps 1 PCAAD bitmap option 0 off 1 on SavePhaseData 0 phase data save option 0 don t save 1 save phase data PatternPlotType 1 default pattern plot type 1 polar 2 rectangular 3 3D ImpedanceP lot Type 0 default impedance plot type 0 Smith chart 1 VSWR RL PatternAzimuthAngle 0 0 azimuth angle for pattern plots PatternStepSize 1 0 step size for pattern plots 3DAzimuthStep 6 0 azimuth step size for 3 D plots 3DElevationStep 2 0 elevation step size for 3 D plots UpperHemisphereOnly 0 3D plot type 0 both hemispheres 1 upper only PlanarPlotData 1Color 255 color for data set 1 pattern plots PlanarPlotData 2Color 16711680 color for data set 2 pattern plots AngleCursor 65535 color for angle cursor P lotBackgroundColor 12632256 color for plot background RL VSWRP lotData 1Color 255 color for data set 1 RL VSWR RL VSWRP LlotData 2Color 16711680 color for data set 1 RL VSWR RectangularPatternPlotLabel Pattern qB vertical label on rectangular PatternPlaneType 1 type of pattern cut SmithPlotData 1Color 255 color for data set 1 Smith plot SmithPlotData 2Color 16711680 color for data set 2 Smith plot SmithPlotData 3Color 32768 color for data set 3 Smith plot SmithPlotData 4Color 16744700 color for data set 4 Smith plot SmithPlotData 5Col
67. for planar arrays Arrays of subarrays or elements with arbitrary patterns and planar arrays with elements having arbitrary positions can also be treated and pattern synthesis can be performed for linear arrays using the Woodward Lawson method The array pattern routines are very flexible allowing you to specify amplitude and phase variations amplitude and phase errors and the type of radiating element D 1 Uniform Linear Array Design and Analysis This routine is used to plot patterns and z compute directivity of a linear array antenna You can specify array size amplitude taper phase distribution and element type Co pol and d cross pol patterns can be calculated in an arbitrary elevation plane and can be plotted either separately or together on a polar or rectangular pattern plot or saved to data files The routine can also be used to compute the directivity of the array As indicated in the picture at the top left of the form the array is assumed to lie along the x axis if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The pattern is computed using the array factor of the array multiplied by the element factor Mutual coupling effects are not included in this routine Directivity is computed by numerical integration of the pattern which can be time consuming for large arrays The maximum size of the array is limited to 200 elements This routine uses three
68. from most of the PCAAD antenna routines to plot patterns or used independently from the PLOT menu to plot patterns from a data file Data files of this type can be generated from most of the PCAAD routines and are given the default file extension 3DP to distinguish them from planar pattern data files The 3 D pattern plot can also be printed on your printer or exported to another application using the Windows clipboard and the Copy Graph command from the Edit menu For 3D volumetric patterns the following data file format is used The first line has three values the elevation angle step size degrees the azimuth angle step size degrees and the maximum elevation angle range 90 degrees for upper hemisphere only or 180 degrees for both hemispheres This is followed by N 1 360 azimuth angle step size lines one for each azimuth angle Each of these lines contains 1 90 elevation angle step size pattern values in dB for each elevation angle Note this format is slightly different from that used in PCAAD 5 0 which only allowed plotting of the upper hemisphere and thus did not require the third entry of the first line To make PCAAD 5 0 3D data files compatible with PCAAD 6 0 simply edit the 3DP data file and add the value 90 to the end of the first line The routine has three slider controls to allow adjustment of the plot size the elevation view angle and the azimuth view angle The plot is redrawn after each adjus
69. ghly accurate and efficient algorithm discussed in reference 19 The Taylor distribution option requires sidelobe level as well as the n bar parameter to be entered the n bar parameter must be in the range from 2 to 6 The Taylor coefficients are computed using the algorithm of reference 20 which is much more accurate and efficient for large arrays than the null matching or aperture sampling techniques The cosine on a pedestal distribution requires entry of the pedestal height C in negative dB Data read from an ASCII data file should be in absolute not dB voltage or current form not power with one line for each element in the array If the size of the array is larger than the number of elements in the specified data file the unspecified element amplitudes will be set to zero The elements are counted by rows along the x dimension from left to right You also have the option of adding gaussian distributed zero mean random errors to any amplitude distribution This is done by specifying the rms value or standard deviation of the errors in dB specifying a value of zero rms error implies no amplitude error Entering a new value for the rms error will cause the amplitude excitation to be re computed and updated in the list box The excitation amplitudes for the array elements are shown in the list box in the amplitude distribution window in absolute form voltage or current amplitudes and in dB The scroll bar can be used to scroll through
70. h angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button You may view the wire geometry in three dimensions by clicking the Show Geometry button The perspective view may be rotated in elevation and azimuth using the scroll bars at the sides of the graph and can be adjusted in size by using the zoom scroll bar Click the Compute button to begin computation of the moment method solution When this calculation is complete the gain directivity radiation efficiency port impedances and mode currents will be listed The specified patterns are also calculated and may be plotted using the Plot Patterns button or saved to data files After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors As in the case of the planar dipole array this routine computes the input impedance at each port as seen looking into the wire terminals and does not directly include the series load impedance if present Similarly the power dissipated in the antenna does not include power lost in the series generator impedances If a port has a load impedance without
71. he dielectric constant the substrate spacing and the line width Click the Compute Zo button to compute and print the characteristic impedance and the effective dielectric constant for the line When calculating line width for microstrip design you will enter the characteristic impedance the dielectric constant and the substrate thickness Click the Compute width button to compute and print the required line width and the effective dielectric constant for the line You may compute the attenuation for the line for either the line analysis or the line design case Enter the frequency the loss tangent of the dielectric filling material and the conductivity of the microstrip conductors The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute Attenuation button and the attenuation due to dielectric loss conductor loss and the total attenuation will be printed in dB cm 85 Validation Consider the design of a 50 Q microstrip line on a substrate with a dielectric constant of 2 08 and a thickness of 0 159 cm at a frequency of 5 GHz The conductors are copper and the dielectric loss tangent is 0 0004 This example corresponds to Example 6 2 in 10 and results from 10 are compared with PCAAD below Quantity Reference 10 PCAAD 6 0 Line width 0 508 cm 0 508 cm Effective permittivity 1 80 1 806 Conduc
72. ient numerical integration technique The aperture efficiency and directivity of prime focus parabolic antennas are characterized by assuming an idealized feed pattern of the cos form 2 Another routine uses numerical aperture integration to compute the secondary radiation patterns and directivity for prime focus reflectors with arbitrary feed patterns In PCAAD 6 0 the phase center is calculated for sectoral pyramidal corrugated pyramidal diagonal conical and corrugated conical horn antennas using the derivative method with numerical integration of reference 29 The phase center of an antenna is defined as the apparent center along the axis of the main beam of the circular far zone phase fronts For an ideal point source the phase center is located at the point source For small apertures with uniform phase the phase center is located at the center of the aperture For antennas with non uniform phase however the phase center may be behind or in front of the aperture and is generally different for different azimuthal planes In many cases a unique phase center cannot be defined The phase center location calculated in PCAAD may not be accurate for horns with very wide angles or very large phase errors 60 E 1 Traveling Wave Line Source Analysis This routine calculates the pattern and directivity for a traveling wave electric line source antenna on the z axis Examples of such antennas include long wire antennas dielectri
73. ion These values are listed for the selected matching network and solution For the stub tuners the characteristic impedance of the transmission line and stub are assumed to be the same as the characteristic impedance of the Smith chart Only a single impedance data set can be matched at one time to change the data set to be matched turn off the impedance matching feature select a data point on the new data set and turn impedance matching back on Once the matching parameters have been selected the routine calculates the input impedance seen looking into the matching network at each frequency and plots this as a new impedance locus on the chart The user can study the effect of changing matching circuits the match frequency and different matching solutions very easily with this routine The effect of changes in component values can be studied simply be entering new values in the component value boxes Note that for data sets having a wide frequency range between data points it is possible that the plotted impedance loci for the original or matched data sets may run off the edge of the chart this is because the accuracy of interpolation may not be sufficient If this is a problem interpolation may be turned off in the Plot Options window When the impedance matching feature is in use no further data sets may be read A 5 VSWR Return Loss Plot This routine plots up to two sets of impedance data as either VSWR or return loss in dB
74. ion for three different types of conversions conversion of dimensions between meters centimeters millimeters inches and mils conversion of return loss and VSWR between return loss reflection coefficient magnitude VSWR and mismatch loss and conversion of dB and ratios between ratios in dB nepers power ratios and voltage ratios Each of these functions operate in the same way Simply enter the known value in the appropriate text box press Enter and the converted values will appear in the remaining boxes Note that all dimensions must be greater than zero return loss reflection coefficient magnitude mismatch loss voltage ratio and power ratio must be non negative and VSWR must be unity or larger Validation Consider an antenna having an input VSWR of 2 0 Entering this value in the VSWR box of the calculator routine and pressing Enter shows that the input reflection coefficient magnitude is 0 3333 the input return loss is 9 54 dB and the mismatch loss is 0 512 dB 100 1 D M Pozar PCAAD 5 0 Personal Computer Aided Antenna Design Antenna Design Associates Leverett MA 2002 2 C A Balanis Antenna Theory Analysis and Design 2nd edition John Wiley and Sons New York NY 1997 3 W L Stutzman and G A Thiele Antenna Theory and Design 2nd edition John Wiley and Sons New York NY 1998 4 J D Kraus Antennas 2nd edition McGraw Hill New York NY 1988 5 T Milligan Modern Antenna
75. kness of 0 159 cm and a feed probe positioned 1 0 cm from the edge of the patch This example is given in reference 9 with the following results compared with Carver s model and the cavity model from PCAAD 75 Quantity Reference 9 Carver Model Cavity Model Resonant frequency 2 0 GHz 1 94 GHz 1 97 GHz Resonant resistance 336 Q 192 Q Bandwidth 0 7 12 1 7 E plane beamwidth 102 103 101 H plane beamwidth 85 86 86 Directivity 7 0 dB 7 0 dB 7 0 dB Validation 2 Consider a probe fed rectangular patch with a length of 1 8 cm a width of 2 505 cm a substrate with a dielectric constant of 2 2 and a thickness of 0 159 cm The probe is positioned 0 5 cm from the edge of the patch Results from the cavity model of PCAAD are plotted on the Smith chart below and compared with measured data Agreement is very good particularly near resonance Figure 7 Smith chart plot of calculated black and measured blue data for a 76 probe fed rectangular microstrip antenna F 3 Rectangular Line Fed Patch Analysis This routine analyzes a rectangular microstrip line fed microstrip antenna using the transmission line model discussed in reference 9 The patch is treated as a transmission line with equivalent end admittances to account for radiation and length extensions are used to account for fringing fields at the radiating edges The transmission line circuit is used to compute C input impedance versus freque
76. length is 5 cm the radius is 0 001 cm the spacing between the elements is 5 cm and the frequency is 3 GHz The generator impedance is 0 Q and the voltage sources are phased to scan the beam to 45 in the H plane Five PWS modes are used on each dipole This geometry is the same as that treated on pp 350 351 in reference 3 Input impedance magnitudes from 3 are compared below with data computed from PCAAD 6 0 Dipole Generator Zin Zin Zin Voltage PCAAD 6 0 PCAAD 6 0 Ref 3 1 1 0 0 107 1 j 9 6 Q 107 5 Q 107 1 Q 2 1 0 127 97 8 j 42 0 Q 106 4 Q 105 9 Q 3 1 0 254 91 0 j 46 0 Q 102 0 Q 101 5 Q 4 1 0 381 87 8 j 45 3 Q 98 8 Q 98 2 Q a 1 0 508 86 4 j 43 9 Q 96 9 Q 96 3 Q 6 1 0 635 85 9 j 42 5 Q 95 8 Q 95 2 Q 7 1 0 762 86 1 j 41 0 Q 95 3 Q 94 7 Q 8 1 0 889 87 5 j 39 3 Q 95 9 Q 95 4 Q 9 1 0 1016 90 7 j 38 9 Q 98 7 Q 98 2 Q 10 1 0 1143 95 0 j 42 6 Q 104 2 Q 103 7 Q 11 1 0 1270 92 8 j 55 2 Q 108 0 Q 107 3 Q 12 1 0 1397 57 4 j 47 8 Q 74 7 Q 74 0 Q The H plane pattern for this case is shown in Figure 2 below and is in good agreement with the pattern in 3 the pattern in 3 is scanned to 45 while the PCAAD results are for an array scanned to 45 the difference can be attributed to a difference in numbering the dipoles 33 Figure 2 H plane pattern of the dipole array 34 C 7 Log Periodic Dipole Array Design This routine gives an approximate design for a log periodic dipole
77. ll through the list of impedances The routine also computes the approximate bandwidth the radiation efficiency and the directivity of the antenna At this point you can plot the impedance locus versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button 79 Validation Consider a proximity coupled patch with a length of 2 5 cm a width of 4 0 cm and a substrate with a dielectric constant of 2 2 and a thickness of 0 316 cm The feed height is 0 158 cm and the feed line width is 0 5 cm The length of the stub is 1 25 cm At 3 6 GHz PCAAD gives an input impedance of 34 j 3 Q while measured data from 6 gives an impedance of about 40 j 3 Q 80 F 5 Rectangular Aperture Coupled Patch Analysis This routine analyzes a rectangular aperture coupled microstrip antenna 15 using a cavity L model solution for the patch combined with the oo ee reciprocity method 16 for treating the slot feed and microstrip line The patch is modeled as a lossy cavity with magnetic sidewalls and the Q is found by integrating the radiated fields of the patch Le
78. lossary of antenna terms included with Short Course PCAAD 6 0 is intended for use by systems and design engineers researchers and students who need a quick solution to a canonical antenna design or analysis problem Most of the routines in PCAAD 6 0 involve basic antenna elements whose theory and characteristics are thoroughly described in a number of texts on antennas 2 9 All of the solutions used in PCAAD 6 0 are based on these results or on similar well established and proven methods B Disclaimer This software package has been written and tested with care Nevertheless this software and its associated user s manual are provided as is without warranty of any kind Neither the author nor Antenna Design Associates Inc make any warranties expressed or implied that the software or the manual are free of error or will meet the requirements of any particular application The software should not be relied upon for the generation of data where such data if incorrect or inapplicable could result in loss of property or personal injury Any use of the software or the manual in such a manner is at the user s own risk The author and Antenna Design Associates Inc disclaim all liability for direct incidental or consequential damages resulting from any use of the software or manual II Getting Started With PCAAD 6 0 A System Requirements PCAAD 6 0 will operate on PC compatible computers running Windows 98 Windows 2000 Windows XP
79. lue of the pattern plot to view the entire pattern The maximum size of the array is limited to 200 elements Begin by entering the operating frequency the number of elements in the array and the element spacing The program will calculate discrete angles where the pattern will be sampled and list these in the scroll box The desired pattern value in dB can then be filled in the text box for each angle Use the scroll bar to scroll through the set of samples The routine will then compute the required amplitude and phase necessary to reproduce the desired pattern A property of the Woodward Lawson synthesis method is that it will provide a pattern that exactly matches the desired pattern at the sample angles but will vary away from those angles Validation Consider the synthesis of a sector pattern with an 11 element array having 0 54 spacing The sector pattern is defined as 0 dB between the angles of 45 and 45 and 60 dB elsewhere The following pattern values are entered at the sample points in the routine 65 4 60 dB 46 7 60 dB 33 21 0 dB 210 3 0 dB 10 5 0 dB 54 0 0 0 dB The resulting synthesized pattern is plotted below Note that the pattern values match those listed above 10 Pattern dB 20 4 afereme eme n _ 30 i i i 90 60 30 0 30 60 Theta Figure 5 Synthesized sector pattern for an 11 element array 55 D 8 Grating Lobe Diagram for a Planar Array
80. mate of the resonant frequency and input impedance for these antennas but be aware that these routines will not be as accurate as full wave solutions Use of the integrated Smith chart routine gives quick results for microstrip antenna designs The routines also compute patterns and directivity F 1 Rectangular Probe Fed Patch Analysis Carver model This routine analyzes a rectangular probe fed microstrip antenna using Carver s transmission line model discussed in references 6 and 14 It treats the patch as a transmission line with equivalent end admittances to account for radiation and length extensions are used to account for fringing fields at the radiating edges The radiation patterns are found from the Pa equivalent magnetic currents for the dominant TMo mode at the edges of the patch including the sidewall contributions The sidewall currents do not contribute to the principal plane patterns but do have an effect on cross pol fields and the directivity which is calculated by integrating the far field patterns This solution generally gives good results for microstrip antennas on thin substrates with low dielectric constants Enter the patch length in the resonant direction the patch width the dielectric constant the substrate thickness the dielectric loss tangent and the distance of the probe from the radiating edge of the patch The routine will then compute the approximate resonant frequency the input resis
81. mouse to click on any data point and read the exact value of its impedance in the data box at the top left of the window This display also gives the corresponding normalized impedance and the reflection coefficient for that impedance The chart also shows a constant VSWR circle dashed circle which may be adjusted by either dragging with the mouse cursor or by entering a new value in the VSWR data entry box at the left side of the chart Similarly the chart also shows a dashed radial line indicating wavelengths toward the load WTL and wavelengths toward the generator WTG This line may be set by dragging with the mouse or by entering a value of WTL or WTG in the appropriate data box In addition the VSWR and WTL WTG cursors may be set to a particular data point by double clicking on that point Smith chart options such as interpolation characteristic impedance a rotated 1 jx circle colors and other display options can be set by clicking the Plot Options button Colors can also be set from the Default Plot Colors window available under Plot on the main menu bar this window also allows saving of your color selections as defaults Each impedance data set can be identified with a movable text label The label is initially set as the filename for that data set if the data was read from a file or the name of the calling routine if the data was obtained from another PCAAD routine You can also set the labels from the Plot Options window a
82. ncy The radiation patterns are found from the equivalent magnetic currents for the dominant TM mode at the edges of the patch The directivity is calculated by integrating the far field patterns This solution has been validated for a large number of practical designs and generally gives good results for microstrip antennas on thin substrates with low dielectric constants Enter the patch length in the resonant direction the patch width the dielectric constant the substrate thickness the dielectric loss tangent and the width of the microstrip feed line The routine will compute and display the required feed line width for a 50Q line enter a new value if your line width is different The routine will then estimate the resonant frequency of the antenna and suggest a frequency step size These values are displayed along with the default number of frequency points in three boxes to the right of the Compute button Click the Compute button to accept these values for the frequency sweep or enter new values for the sweep center frequency the frequency step size or the number of frequency points The routine will then compute the input impedance of the antenna over this frequency sweep and display the results in the list box If necessary use the scroll bar at the right of the box to scroll through the list of impedances The routine also computes the approximate bandwidth the radiation efficiency and the directivity of the antenn
83. nd the labels can be turned on or off using the check box for Show Data Point and Set Labels enter blanks for the data set label if you want data point labels but not a data set label Use the mouse to drag the label to the desired position on the Smith chart PCAAD also features a general purpose impedance matching routine coupled to the Smith chart With one or more but less than five data sets displayed first select a data set and a matching frequency by clicking on the desired data point if you do not select a data point the program will use the midpoint of the first data set Then turn on the impedance matching feature by clicking the On button in the Impedance Matching frame The response of the matched 17 impedance data will be displayed You may change the matching frequency using the scroll box the impedance data set must have frequency labels for each data point You may choose the type of matching circuit from the list box a quarter wave transformer LC networks open and short circuit shunt stubs and open and short circuit series stubs are available see 10 for a discussion of impedance matching techniques Except for the quarter wave transformer each of these circuits yields two different matching solutions which can be selected with the buttons marked Solution 1 and Solution 2 Each matching solution has two parameters transformer impedance and length series and shunt components values or stub length and posit
84. ngth extensions are used to account for fringing fields at the radiating edges of the patch and closed form approximations for short slots are used for the slot self conductance and susceptance The radiation patterns are found from the equivalent magnetic currents for the dominant TM mode at the edges of the patch The directivity is calculated by integrating the far field patterns It is assumed that the coupling slot is centered under the patch the feed line is centered across the slot and that the feed line is terminated with an open circuited stub First enter the parameters for the patch side of the antenna geometry the substrate thickness dielectric constant patch length resonant dimension patch width slot length long dimension and slot width short dimension Then enter the parameters for the feed side of the antenna the substrate thickness dielectric constant feed line width and tuning stub length measured from the center of the slot to the end of the stub The routine will then estimate the resonant frequency of the antenna and suggest a frequency step size These values are displayed along with the default number of frequency points in three boxes to the right of the Compute button Click the Compute button to accept these values for the frequency sweep or enter new values for the sweep center frequency the frequency step size or the number of frequency points The routine will then compute the input impedan
85. nna parameters The routine prints out the maximum phase error at the edge of the aperture relative to the center of the aperture the directivity of the horn and the E and H plane phase centers which are always identical Pattern plots can be made in the E and H planes of the horn or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation A square diagonal horn with a width of 12 7 cm and a very long length is described in 28 At 16 5 GHz the 3 dB beamwidth is given as 8 5 in both principal planes and the diagonal planes PCAAD gives a 3 dB beamwidth of 8 3 Reference 28 lists the aperture efficiency of the diagonal horn as 81 which given the aperture area yields a directivity of 27 0 dB PCAAD gives 27 0 dB The patterns show relatively high cross polarization lobes of 15 dB in the diagonal planes 68 E 7 Conical and Corrugated Conical Horn Analysis These two routines compute the patterns and directivity of a conical TE mode or a corrugated conical HE mode horn antenna The choice of conical or corrugated horn is made from the Aperture antenna menu The principle plane patterns are computed using an efficient numerical integration algorithm that includes the quadratic phase
86. not by using the check box on the Default Plot Types menu For 3D volumetric patterns the following data file format is used the first line has three values the elevation angle step size degrees the azimuth angle step size degrees and the maximum elevation angle range 90 degrees for upper hemisphere only or 180 degrees for both hemispheres This is followed by N 1 360 azimuth angle step size lines one for each azimuth angle Each of these lines contains 90 elevation angle step size pattern values in dB for each elevation angle Note this format is slightly different from that used in PCAAD 5 0 which only allowed plotting of the upper hemisphere and thus did not require the third entry of the first line To make PCAAD 5 0 3D data files compatible with PCAAD 6 0 simply edit the 3DP data file and add the value 90 to the end of the first line E Impedance Calculation and Plotting Several routines such as the wire antenna and microstrip antenna routines perform calculations of input impedance over a swept frequency range The parameters of this sweep are specified as the center frequency the frequency step size and the number of frequency points You can enter specific values for these parameters in the appropriate boxes or allow PCAAD to provide estimates by clicking the Compute button Note that the center frequency parameter refers to the middle of the frequency sweep range which may be different from the o
87. o have the same length and radius Each dipole is center fed with an arbitrary voltage generator with a series generator impedance As shown in the graphic the dipoles are all parallel to the x axis and are numbered by rows along the x axis Begin by entering the frequency the number of dipoles in the x and y directions and the spacings center to center of the dipoles in the x and y directions Also enter the dipole length the dipole radius the number of PWS modes on each dipole and the series generator resistance The generator impedance is the same for all dipoles Next specify the generator voltage at each dipole using the scroll bar and boxes The dipole index numbered along the x axis by rows is listed in the box to the right of the scroll bar followed by boxes for the generator voltage magnitude and phase in degrees Use the scroll bar to scroll through the elements to set or change generator voltages Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button When all data is entered click the Compute button to calculate the moment method solution The input impedance for each dipole will be listed in the box below the Compute button use the sc
88. or 4194304 color for data set 5 Smith plot The above values are typical entries that are set upon installation but most of these values will change according to the plotting and color options that are set and saved when using the Plot Default Types and Plot Default Colors options from the Plot menu It is recommended that the user not directly modify the PCAAD6 INI file except perhaps to set the vertical axis label for the rectangular pattern plot routine HI Using PCAAD 6 0 General Instructions A Organization of PCAAD 6 0 The main window is displayed when PCAAD 6 0 starts and forms the background for all modules and routines The menu bar at the top of the window categorizes the antenna modules into several groups along with useful plotting routines and other utilities Specific routines are listed and summarized below Plot Polar Pattern Plot Rectangular Pattern Plot 3 D Pattern Plot Smith Chart Plot VSWR Return Loss Plot Plot Default Types Plot Default Colors Exit Edit Copy Window Copy Graph Copy Text Paste Text Edit File Print Window Wire Wire Dipole Antenna Analysis Wire Dipole RCS Analysis V dipole Antenna Analysis Wire Loop Antenna Analysis Yagi Dipole Array Analysis Finite Wire Dipole Array Log Periodic Dipole Array Design Log Periodic Dipole Array Analysis General Wire Antenna Analysis Arrays Uniform Linear Array Linear Subarray Uniform Rectangular Array Uniform Circular Plana
89. ot and the angle cursor are shown and can be changed from their default colors of red blue gray and yellow by clicking the appropriate Change button This may make the display more legible for monochrome or notebook computer displays and for importing the graph into word processors and other Windows software The pattern plot colors match those used in the display boxes at the left of the plotting routine window Each pattern can be identified with a movable text label The text is set from Plot Options and the labels can be turned on or off using the check box for Show Pattern Labels Use the mouse to drag the label to the desired position on the plot 14 A 2 Rectangular Pattern Plot This routine plots up to two planar antenna radiation patterns in rectangular form It can be called directly from most of the PCAAD antenna routines to plot patterns or used independently from the Plot menu to plot patterns from a data file The routine also computes the main beam pointing angle the 3 dB beamwidth of the main beam and provides a movable angle cursor to read pattern values at any angle The Plot Options window allows control of various plot parameters such as the number of divisions scales plotting ranges offsets and colors The resulting plot can be printed on your printer or exported to another application using the Windows clipboard and the Copy Graph command from the Edit menu To read pattern data from a data file click the Rea
90. owing A user friendly Windows interface Full 32 bit compiled software Very simple and intuitive operation Fast results for first cut designs Graphic illustrations of each antenna geometry Polar rectangular and 3 D pattern plots Smith chart VSWR and return loss plots for input impedance Data file output for patterns and impedance matrices On line help Validation examples for each analysis routine A What s New in PCAAD 6 0 PCAAD 6 0 for Windows contains substantial improvements and enhancements compared to the previous version PCAAD 5 0 1 Some of the specific improvements in this version of PCAAD are listed below analysis of diagonal horn antennas phase center calculation for horn antennas analysis of rectangular and circular aperture antennas data for antenna noise temperature calculation of radio link loss calculation of polarization mismatch data for atmospheric and rain attenuation calculation of axial ratio due to amplitude and phase errors calculation of array sidelobe level due to random errors co and cross pol patterns for all antennas pattern phase data can be saved to pattern file calculator for useful microwave and antenna functions plot up to five data sets on Smith chart plots log files written for all wire antenna solutions improved accuracy for conical horns arbitrary grid angle allowed in Grating Lobe routine can copy active window to clipboard improved graphics error checking and Help G
91. pace Using the cursor to move to the intersection of a surface wave circle and the E plane scan plane v 0 indicates a scan blindness will occur at 45 in close agreement with the result of 46 from the full wave solution in 13 57 D 9 Effect of Array Excitation Errors and Failed Elements The effect of random amplitude and phase errors on the pattern of an array is to raise the sidelobe level and decrease the gain This routine computes the average sidelobe level and average loss in gain for an array having random amplitude and phase errors The routine also includes the effect of failed elements in an array and the quantization phase error and quantization lobe level due to phase shifter quantization This routine is based on results given in 17 and 26 Begin by entering the RMS amplitude error in dB followed by the RMS phase error in degrees Each of these errors is assumed to have a normal distribution with zero mean The phase error may be positive or negative If desired also enter the percentage of elements in the array considered to have failed this value should be less than 100 Click the Compute button to calculate the resulting average sidelobe level and loss in gain due to the entered errors and failed elements Note that the average sidelobe level is given relative to isotropic The array directivity must be known to convert this value to a sidelobe level relative to the main beam of the array
92. perating frequency of the antenna Impedance versus frequency can be plotted on a Smith Chart plot or on a VSWR Return Loss plot the default type of impedance plot can be set from the Plot Default Types option from the Plot menu The Smith chart window also contains a powerful impedance matching utility F Help PCAAD 6 0 contains a comprehensive help file in standard Windows format with convenient cross references and search options The help file is context sensitive meaning that you can simply press the F1 key while using any analysis routine to get help on that particular routine Pressing the F1 key while on the main window will bring up the help contents for PCAAD 6 0 Help can also be accessed by clicking Help Context Help from the main menu bar You can also access the mini short course on antenna theory from the Help menu The short course is grouped by chapters into individual PDF files along with a Glossary and a quiz on antennas Select Short Course from the Help menu and the desired file from the directory listing The file should open with the Acrobat Reader You need to have the Acrobat Reader installed on your computer IV Using PCAAD 6 0 Instructions and Examples This chapter will describe in detail the operation of each antenna transmission line and utility routine in PCAAD 6 0 in terms of the input and output data and a brief discussion of the theory of the solution Validation examples are also included for
93. ques to reduce the effects of quantization lobes Setting the phase shifter bits to Off turns off the phase shifter calculation functions 58 Validation The average sidelobe level due to amplitude and phase errors relative to isotropic is given by Orr 2 2 SEL O Os o dB 20 where o 10 1 is the rms amplitude error and is the rms phase error in radians Direct calculations shows that a 10 rms phase error leads to an average isotropic sidelobe level of 15 2 dB and a 1 5 dB rms amplitude error leads to an average isotropic sidelobe level of 14 5 dB PCAAD gives 15 2 dB and 14 5 dB respectively for these two cases If 50 of the array elements have failed the gain is seen to be reduced by 3 dB as expected 59 E The Aperture Antennas Menu This set of routines are used for the analysis of various aperture antennas Patterns and directivity can be calculated for line sources rectangular and circular apertures E and H plane sectoral horns pyramidal horns conical horns and corrugated horns The waveguide horns are analyzed by the usual assumption of a waveguide field distribution in the aperture plane multiplied by a quadratic phase factor 2 3 For the sectoral and pyramidal horns this results in closed form expressions for patterns and directivity in terms of Fresnel integrals No such results are available for the conical or corrugated conical horns so these cases are treated using a fairly effic
94. r Array Arbitrary Planar Array Infinite Printed Dipole Array Linear Array Pattern Synthesis Grating Lobe Diagram Effect of Array Excitation Errors plot patterns in polar form plot patterns in rectangular form plot patterns in 3 D form plot and tune impedance on a Smith chart plot VSWR or Return Loss set defaults for pattern and impedance plot types set color preferences for plots exit PCAAD 6 0 copy current Window to Windows clipboard copy current plot to Windows clipboard copy selected text to Windows clipboard paste text from Windows clipboard invoke system text editor Notepad print current PCAAD window and its contents analyze wire dipole antenna compute RCS of wire dipole analysis of V dipole wire antenna analysis of wire loop antenna analyze wire dipole Yagi array analyze finite planar dipole array design log periodic dipole array analysis of log periodic dipole array analyze arbitrary wire antenna geometry patterns and directivity of a uniform linear array patterns of a linear array of subarrays patterns and directivity of a rectangular array patterns and directivity of a circular planar array patterns and directivity of an arbitrary planar array active impedance of infinite printed dipole array Woodward Lawson array synthesis grating lobe diagram for a planar array effect of array excitation errors failed elements Apertures Traveling wave Line Source Rectangular Ape
95. r of the array multiplied by the element factor Mutual coupling effects are not included in this routine Directivity is computed by numerical integration of the pattern which can be very time consuming for large arrays There is no limit to the maximum size of the array but the directivity calculation will be unacceptably time consuming for more than about 100 elements Validation 1 First consider a circular planar array with an outer radius of 14 and an element spacing of 0 6A with isotropic elements This results in a uniform rectangular grid of 3x3 elements for which the circular array routine gives a directivity of 11 6 dB and a half power beamwidth of 30 6 The rectangular planar array routine can be used for the same geometry and gives identical results Validation 2 Next consider a circular planar array with an outer radius of 5A and an element spacing of 0 54 with rectangular microstrip patches of size 0 3A x 0 3A This results in an array of 317 elements For a uniform amplitude distribution PCAAD 6 0 gives a directivity of 30 1 dB for this array Using the formula D 47 R A gives a value of 29 9 dB 50 D 5 Arbitrary Planar Array Design and Analysis This routine is used to plot patterns and compute directivity of a planar array of elements having arbitrary locations in the x y plane and arbitrary excitations This can be useful for treating arrays that do not conform to the linear or planar apert
96. radius for each dipole in the array The dipoles are numbered starting from the largest element the last spacing value is not used Pattern plots can be made in the E and H planes of the dipole or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button When all data is entered click the Compute button to calculate the moment method solution The input impedance directivity and gain accounting for power lost in the termination resistor and the front to back ratio are listed along with the magnitude and phase of the terminal currents at each dipole these values include the 180 reversal introduced by the feed line This data can be used to observe how the active region moves along the array as frequency changes 36 Validation Consider a log periodic dipole array having 18 elements and 0 169 T 0 917 with the largest dipole having a length of 75 cm and radius of 0 3 cm Assume a characteristic impedance of 83 Q The table below compares the calculated input impedance and gain with values from 3 Five expansion modes per dipole were used in the PCAAD solution Frequency Reference 3 PCAAD 6 0 MHz Zin Q Gain dB Zin Q Gain dB 200 69 7 8 8 71 6 9 0 300 72 4 9 4 7243
97. ransmission line circuit is used to compute input impedance versus frequency The radiation patterns are found from the equivalent magnetic currents for the dominant TMo mode at the edges of the patch The directivity is calculated by integrating the far field patterns This solution is not highly accurate but generally gives reasonable results for microstrip antennas on thin substrates with low dielectric constants Enter the patch length in the resonant direction the patch width the total substrate thickness d the dielectric constant and the height 4 of the feed line above the ground plane this must be less than the substrate thickness Next enter the width of the microstrip feed line and the loss tangent of the substrate material Finally enter the stub length as measured from the edge of the patch to the end of the stub The routine will then estimate the resonant frequency of the antenna and suggest a frequency step size These values are displayed along with the default number of frequency points in three boxes to the right of the Compute button Click the Compute button to accept these values for the frequency sweep or enter new values for the sweep center frequency the frequency step size or the number of frequency points The routine will then compute the input impedance of the antenna over this frequency sweep and display the results in the list box If necessary use the scroll bar at the right of the box to scro
98. receiver the frequency the polarization mismatch enter 0 dB for no mismatch and the atmospheric attenuation The routine calculates the link loss assuming matched antennas Validation Example 13 4 of 10 describes the link loss of a DBS satellite with a transmit antenna gain of 34 0 dB a receive antenna gain of 33 5 dB a range of 39 000 km and an operating frequency of 12 45 GHz PCAAD gives a link loss of 138 7 dB in agreement with the result of 10 95 H 2 Polarization Mismatch Between Two Antennas This routine calculates the maximum and minimum polarization mismatch between two arbitrarily polarized antennas using the formulation presented in 24 AR tx AR rx x Enter the axial ratio of each antenna and specify the polarization sense right hand or left hand For an ideal linearly polarized antenna enter a large value such as 100 dB for its axial ratio The routine then computes the maximum and minimum losses due to polarization mismatch Note that these values being defined as losses appear as positive dB The actual loss in practice will depend on the relative orientation of the polarization ellipses of the two antennas but will always be between the minimum and maximum values given by this routine Validation 1 Consider the mismatch between an ideal circularly polarized antenna and an ideal linearly polarized antenna By entering 0 dB for the axial ratio of the circularly polarized antenna
99. rn type and parameters with the Pattern Type Select button Validation 1 An open ended X band waveguide has an E plane aperture dimension of 1 016 cm and an H plane aperture dimension of 2 286 cm At 10 GHz the linear array routine of PCAAD with one waveguide element in the array gives a directivity of 6 3 dB The rectangular aperture routine with a uniform amplitude taper in the E plane and a cosine taper in the H plane gives a directivity of 6 3 dB Validation 2 A rectangular array of 24 x 24 microstrip patches with lengths and widths of 0 34 element spacings of 0 54 and uniform amplitude and phase distributions yields a directivity of 32 6 dB using the PCAAD planar array routine The rectangular aperture routine for an aperture of 12 x 12A with uniform amplitude tapers in both directions gives a directivity of 32 6 dB 62 E 3 Circular Aperture Antenna Analysis This routine computes the patterns and directivity of a circular aperture antenna having a uniform phase distribution and either uniform or a parabolic tapered amplitude distributions in D the radial plane The patterns are computed using closed form expressions from References 2 3 For accuracy for small apertures the directivity is calculated by numerical integration when the aperture is smaller than 10 wavelengths in diameter For electrically large apertures the usual directivity approximation of 4m7A A with the appropriate aperture
100. roll bar to scroll through the data The input impedance is that seen looking into the dipole terminals in contrast to the impedance seen from the generator which would include the generator series impedance The routine computes the gain of the array at the main beam position assuming the main beam occurs in the plane where the patterns have been specified The gain is computed in terms of the input power to the dipoles and does not include power dissipated in the generator impedance The logic here is that a realistic source will consist of a voltage generator and a series generator impedance and the power dissipated in the source impedance should not be considered as a loss in the antenna itself The specified patterns are also calculated at the center frequency and may be plotted using the Plot Patterns button or saved to data files The geometry of the dipole 32 may be viewed in three dimensions by clicking the Show Geometry button After each computation data is automatically written to a log file called WIRE LOG located in the PCAAD program directory This data includes the frequency wire radius coordinates of all points on the wire structure the definition of the PWS expansion modes the moment method impedance matrix and the voltage and current vectors The modes are counted from the left to the right of each element along the E plane rows of the array Validation Consider a 12 element linear H plane dipole array The dipole
101. roll through the list of impedances The routine also computes the approximate bandwidth the radiation efficiency and the directivity of the antenna At this point you can plot the impedance locus versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button 83 Validation 1 Consider a circular probe fed patch with a radius of 6 7 cm on a substrate with a dielectric constant of 2 62 and a thickness of 0 16 cm and a probe positioned 5 03 cm from the center of the patch This example is given in 8 using a different cavity model and compared with the following results from PCAAD Quantity Reference 8 PCAAD 6 0 Resonant frequency 793 MHz 796 MHz Resonant resistance 180 Q 219 Q Validation 2 Consider a circular probe fed patch with a radius of 2 78 cm on a substrate with a dielectric constant of 2 32 and a thickness of 0 16 cm and a feed probe at the edge of the patch Reference 9 gives the following data compared with PCAAD Quantity Reference 9 PCAAD 6 0 Resonant frequency 2 00 GHz 1 996 GHz Directivity 7 1 dB 7 1 dB Bandwidth 11
102. rture Antenna Analysis Circular Aperture Antenna Analysis E plane Sectoral Horn H plane Sectoral Horn Pyramidal Horn Corrugated Pyramidal Horn Conical Horn Corrugated Conical Horn Parabolic Reflector approximate Parabolic Reflector patterns Microstrip Rectangular Probe fed Patch Rectangular Probe fed Patch Rectangular Line fed Patch Rectangular Proximity fed Patch Rectangular Aperture Coupled Patch Circular Probe fed Patch Transmission Lines Microstrip Line Covered Microstrip Line Stripline Coaxial Line Rectangular Waveguide Rectangular Waveguide Data Circular Waveguide Surface Waves Miscellaneous Communication Link Loss Polarization Mismatch Atmospheric and Rain Attenuation Axial Ratio vs Excitation Errors Antenna Noise Temperature Calculator Help Help Contents Help Index Context Help Short Course About PCAAD patterns of an arbitrary line source analysis of a rectangular aperture antenna analysis of a circular aperture antenna analysis of an E plane sectoral horn analysis of an H plane sectoral horn analysis of a pyramidal horn analysis of a corrugated pyramidal horn analysis of a conical horn analysis of a corrugated conical horn approximate analysis of prime focus reflector patterns of prime focus reflector probe fed patch analysis Carver s model probe fed patch analysis cavity model line fed patch analysis t line model proximity fed patch analysis t line model aper
103. s The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute Attenuation button and the attenuation due to dielectric loss conductor loss and the total attenuation will be printed in dB cm Validation Consider a circular waveguide with an inner radius of 0 5 cm filled with Teflon dielectric constant of 2 08 loss tangent of 0 0004 The waveguide is gold plated and is operating at 14 GHz This problem is presented as Example 3 2 in 10 with results compared to PCAAD below Quantity Reference 10 PCAAD 6 0 1 1 mode cutoff frequency 12 19 GHz 12 190 GHz 0 1 mode cutoff frequency 15 92 GHz 15 924 GHz TE propagation constant 208 0 rad m 207 984 rad m conductor attenuation 0 00583 dB em 0 0058 dB cm dielectric attenuation 0 0149 dB em 0 0149 dB cm 93 G 8 Surface Wave Analysis This routine computes TM and TE surface wave propagation constants for a grounded dielectric substrate It first determines the number of propagating surface wave modes on the slab acess LEEA EE then uses a Newton Rhapson iteration technique id to find the propagation constants It is based on standard results as found in reference 10 Enter the frequency the substrate dielectric constant and the substrate thickness Click the Compute button to print out the normalized to ko propagation constant for e
104. sinusoidal expansion modes on each dipole can also be chosen this should be an odd number since the dipoles are assumed to be center fed One to three modes is usually sufficient for accurate results The required array parameters include the element spacings in the E and H planes the dipole length and width and the substrate thickness and dielectric constant Input impedance data will be calculated for a fixed azimuth scan angle and for elevation angles from zero to 90 You must enter both the azimuth angle and the elevation step size Since this is a full wave calculation it can be time consuming on slow computers so it is helpful to not specify too small of a step size to avoid unreasonably long run times The input impedance at each elevation angle is listed in the list box as it is computed Scroll through the list using the scroll bar After the entire set of impedance data is calculated you have the option of either saving the data to a data file by clicking the Save As button or plotting the impedance data on a Smith chart or a VSWR Return Loss plot by clicking the Plot Impedance button Validation Consider an infinite array with an E and H plane spacing of 5 cm a dipole length of 3 9 cm a dipole width of 0 02 cm and a substrate with a thickness of 1 9 cm and a dielectric constant of 2 55 and a frequency of 3 GHz This example corresponds to the first case considered in 13 For 0 with three expansion modes per dipol
105. sion modes N Reference 1 PCAAD 6 0 1 73 1 j 42 2 Q 73 1 j 42 2 Q 3 81 2 j 41 3 Q 81 2 j41 3 Q 5 82 8 j 42 0 Q 82 8 j 42 0 Q 7 83 6 j 42 7 Q 83 6 j 42 7 Q The gain of a half wave dipole is from 2 2 15 dB PCAAD 6 0 gives 2 2 dB 23 C 2 Wire Dipole Radar Cross Section Analysis This routine is very similar to the dipole antenna routine except that it computes the bistatic radar cross section RCS for a loaded wire dipole The solution uses the piecewise sinusoidal expansion PWS Galerkin moment method L with the exact exponential integral expressions used for the impedance matrix elements as detailed in references 11 12 This method has proven to be the most accurate and efficient technique for solving thin wire antenna and scattering problems Begin by entering the dipole length the dipole radius and the incidence and scattering angles These angles are measured from the axis of the dipole and have default values of 90 broadside Next enter the number of PWS expansion modes and the mode number of the lumped element load impedance The default number of expansion modes is 3 and the default position of the lumped load is at the terminals of the middle expansion mode Then enter the real and imaginary parts of the load impedance the default values are zero The resonant frequency of the dipole the frequency step size and the default number 7 of frequency points are displayed to the right
106. sis These two routines compute the patterns and directivity of E plane or H plane sectoral horn antennas using closed form expressions from reference 2 The choice of E plane or H plane horn is made from the Aperture antenna menu The directivity expression for the E plane sectoral horn has been corrected according to reference 18 The phase center for both principal planes is also computed Begin by entering the frequency the E plane aperture dimension the H plane aperture dimension and the axial length of the horn This length is the distance from the imaginary apex of the horn to the mouth of the horn not the slant length Also enter the increment for the pattern computation then click the Compute button to compute the principle plane patterns The routine prints out the maximum phase error at the edge of the aperture relative to the center of the aperture the optimum E plane aperture dimension the directivity of the horn and the E and H plane phase centers The optimum aperture dimension is the dimension that will result in maximum directivity for a horn of the same length Pattern plots can be made in the E and H planes of the horn or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Valid
107. sition and beamwidth may not be meaningful and may not be shown The display boxes also show the value of the pattern at the angle indicated by a movable angle cursor The angle cursor is drawn as a dashed radial line and can be moved by either clicking or dragging with the mouse or by using the left and right arrow keys NumLock must be off When using the mouse notice that the mouse cursor changes from an arrow to a cross hair when moved inside the polar plotting region Clicking the mouse inside the polar plot will snap the angle cursor to that angular position Alternatively the angle cursor can be moved by clicking the mouse on the angle cursor note that the mouse cursor changes to a directional icon when over the angle cursor and dragging to the desired position The pattern value display is updated instantly This feature is useful for reading sidelobe or cross pol levels Plot options for the polar and rectangular plotting routines can be selected by clicking the Plot Options button in the plot routine window The angle cursor display function can be turned on or off using the Show Cursor check box Scroll boxes can be used to adjust the number of amplitude divisions from 2 to 8 the step size per division from 3 dB to 20 dB and the maximum value of the plot from 40 dB to 40 dB It is also possible to add a fixed offset value ranging from 40 to 40 dB to each pattern The colors of the plotted pattern curves the background of the pl
108. tance the approximate bandwidth the radiation efficiency and the directivity Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button See the following section for validation examples 74 F 2 Rectangular Probe Fed Patch Analysis cavity model This routine analyzes a rectangular probe fed microstrip antenna using a cavity model similar to that discussed in reference 8 The patch is treated as a lossy cavity to account for radiation and length extensions are used to account for fringing fields at the radiating edges A parallel RLC equivalent circuit is then used to compute the input impedance versus frequency The ia radiation patterns are found from the equivalent magnetic currents for the dominant TMo mode at the edges of the patch The directivity is calculated by integrating the far field patterns This solution generally gives good results for microstrip antennas on thin substrates with low dielectric constants Enter the patch length in the resonant direction the patch width the dielectric constant the substrate thickness the dielectric loss tangent and the distance of the probe from the radiating edge of the patch the probe is ass
109. teristic impedance 41 7Q 41 7Q TE mode cutoff frequency 30 2 GHz 30 2 GHz Conductor attenuation 0 0115 dB em 0 012 dB em Dielectric attenuation 0 145 dB cm 0 144 dB cm 90 G 5 Rectangular Waveguide Analysis This routine computes the cut off frequencies and propagation constants for the five lowest order modes of a rectangular waveguide and the attenuation due to dielectric and conductor losses for the TE mode Begin by entering the E plane narrow wall and H plane broad wall inside dimensions of the guide the dielectric b constant of the material filling the guide and the operating frequency Click the Compute button a and the routine will compute and print the cutoff frequencies of the 1 0 2 0 0 1 1 1 and 0 2 modes if the mode is propagating at the specified frequency the propagation constant will also be printed otherwise it is listed as cut off The formulas used in this routine are standard results as found in reference 10 You can compute attenuation for the dominant TE 9 mode if it is propagating by entering the loss tangent of the dielectric filling material and the conductivity of the waveguide walls The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute Attenuation button and the attenuation due to dielectric loss conductor loss and the total atten
110. tine For example this routine can be used to find patterns of an array of elements having a measured element pattern an array of horn antennas or an array of subarrays You can specify array size number of elements or subarrays the amplitude taper and the phase distribution The element spacing is measured between the centers of adjacent elements or subarrays The element pattern is specified only in the plane of the array and assumed to be constant in the plane orthogonal to the array For this reason the directivity may not be meaningful and is not calculated Without loss of generality the polarization of the elements or subarrays is assumed to be along the x axis Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button As indicated in the picture at the top left of the form the array is assumed to lie along the x axis if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The pattern is computed using the array factor of the array multiplied by the subarray pattern Mutual coupling effects are not included in this routine The maximum size of the array is limited to 200 elem
111. tment of these controls Drawing of the plot can be time consuming on slow computers especially if the elevation and azimuth step sizes are small A color bar near the bottom of the window shows the scale with red corresponding to 0 dB and blue to 30 dB A 4 Smith Chart Plot The Smith Chart plotting routine is a very versatile tool capable of plotting up to five sets of impedance data and incorporating an easy to use impedance matching capability It can be called directly from routines that calculate impedance such as the wire antenna and microstrip element routines or it can 16 be used independently from the Plot menu to plot impedance data from ASCII data files When used with data files the file should be in ASCII form with one line for each data point The real part the imaginary part and an optional data point label up to five characters long should be delimited with commas or spaces The data point labels are commonly used as frequency markers but other parameters can be used as well such as scan angle The impedance data is assumed to be in absolute ohms not normalized form Click the Read Data File button to select a data file Up to five data sets can be displayed except when the impedance matching solution is used The impedance matching response must always be the last data set so further data is prevented from being read when the impedance matching response is on From the Smith chart window you can use the
112. tor attenuation 0 00629 dB em 0 0049 dB cm Dielectric attenuation 0 00208 dB em 0 0021 dB cm 86 G 2 Covered Microstrip Line Analysis This routine implements a full wave moment method solution for the analysis of microstrip line with an optional cover layer The effective dielectric constant the characteristic impedance and the attenuation constant are computed This is a rigorous spectral domain solution using the exact Green s function for a two layer dielectric medium with the spectral perturbation technique 23 for calculating the attenuation constant Begin by entering the bottom layer substrate parameters thickness dielectric constant and loss tangent then the cover layer parameters thickness dielectric constant and loss tangent Set the cover layer thickness to zero if no cover is present in this case the cover layer dielectric constant is not relevant but must be set to a value greater than unity Then enter the frequency line width and the conductivity of the line The conductivity may be entered as a value in Siemens meter or a specific conductor material can be selected from the drop down menu at the right of the conductivity box Click the Compute button and the effective dielectric constant the characteristic impedance and the total attenuation in dB cm will be printed The attenuation includes dielectric loss and loss due to finite conductivity of the strip loss in the ground plane is not incl
113. ture coupled patch analysis cavity model probe fed patch analysis cavity model analysis and design of microstrip line full wave analysis of covered microstrip line analysis and design of stripline analysis of coaxial line analysis of rectangular waveguide standard rectangular waveguide data analysis of circular waveguide analysis of surface waves Friis formula for radio links polarization mismatch between two antennas propagation loss due to atmosphere or rain axial ratio vs amplitude and phase errors antenna sky noise temperature useful antenna and microwave functions contents of Help index for Help context help for PCAAD 6 0 F1 key short course on antennas information about PCAAD 6 0 and your system After selecting a particular antenna or transmission line topic from the main PCAAD menu a window will open for that routine The windows for all routines have the same format a small graphic image of the antenna or transmission line geometry is shown at the top left of the window with data 10 entry at the top right and output data listed below Most routines have a Compute button that is used to initiate computations after all data has been entered Results are displayed after the computation is finished and most routines then allow the option of plotting data saving data in a file or running a new solution Input data values are retained until the window is closed making it easy to change on
114. u This routine plots a grating lobe diagram for a periodic planar array antenna including the optional plotting of surface wave circles A grating lobe diagram can be very helpful for determining the presence and location of grating lobes and the movement of grating lobes with scan angle In conjunction with surface wave circles the grating lobe diagram can be used to predict the location of scan blindness angles in printed array antennas as discussed in reference 13 or other arrays having a structure that supports guided waves This routine provides a zoom control to adjust the size of u v space that is plotted and a convenient readout in u v and theta phi coordinates of the mouse cursor when it is positioned in the visible space region of the grating lobe diagram Begin by entering the array operating frequency and the element spacings center to center in the horizontal and vertical directions Next enter the array grid angle A grid angle of 90 degrees corresponds to a rectangular array while a grid angle of 60 degrees corresponds to an array with a hexagonal grid For a hexagonal grid the maximum element spacings with no grating lobes in visible space are 0 5774 wavelengths horizontal 0 5 wavelengths vertical If you want to plot surface wave circles enter a non zero value for the normalized surface wave propagation constant this can be computed using the Surface Waves routine under the Transmission Lines menu Click th
115. uation will be printed in dB cm Validation Consider a copper K band waveguide of dimensions 1 07 cm x 0 43 cm operating at 15 GHz The guide is filled with Teflon dielectric constant of 2 08 loss tangent of 0 0004 This problem is treated in Example 3 1 of 10 and the results are compared with those from PCAAD below Quantity Reference 10 PCAAD 6 0 1 0 mode cutoff frequency 9 72 GHz 9 720 GHz 2 0 mode cutoff frequency 19 44 GHz 19 440 GHz 0 1 mode cutoff frequency 24 19 GHz 24 188 GHz 1 1 mode cutoff frequency 26 07 GHz 26 068 GHz TE o propagation constant 345 1 rad m 345 08 rad m Conductor attenuation 0 00434 dB em 0 00433 dB cm Dielectric attenuation 0 0103 dB em 0 01034 dB cm 91 G 6 Standard Rectangular Waveguide Data This routine lists data for standard rectangular waveguide including the WR number the standard band letter designation the recommended operating frequency range the cut off frequency for the TE mode and the inner dimensions of the guide The scroll bar at the right side of the list box can be used to b scroll the entries up or down The source data for this routine is stored in the ASCII file a RECWGDAT DAT which you may edit to add or change the data displayed by PCAAD 6 0 The data for each guide is entered on a separate line with spaces or tabs as delimiters between the data elements The routine also allows you to send dimensions for a particular guide to the
116. uded Validation Consider a microstrip line etched on a substrate with a dielectric constant of 2 2 a thickness of 0 16 cm and a loss tangent of 0 01 with a cover layer having a dielectric constant of 2 2 a thickness of 0 16 cm and a loss tangent of 0 01 The copper line is 0 4 cm wide At 4 GHz the following results are obtained and compared with PCAAMT an independent full wave model Quantity PCAAMT PCAAD 6 0 Effective permittivity 2 098 2 100 Characteristic impedance 53 2 Q 54 8 Q Attenuation 0 053 dB cm 0 054 dB cm 87 G 3 Stripline Analysis and Design This routine is used to find the characteristic impedance of a stripline transmission line given the substrate parameters and line width or to find the line width given the substrate parameters and the characteristic impedance Attenuation due to conductor and dielectric loss can also be calculated if desired These solutions employ closed form quasi static formulas that generally give good results for most practical design problems as discussed in reference 10 First choose either the Compute Zo option or the Compute width option by clicking the appropriate radio button at the left side of the window This will change the input statements for the relevant data entry When computing characteristic impedance you will enter the dielectric constant the ground plane spacing the line width and the strip thickness Click the Compute Zo button to compute
117. ular aperture antenna having a uniform phase distribution and either uniform or cosine tapered amplitude E distributions in the E and H planes The patterns are computed using closed form expressions from References 2 3 For accuracy for small apertures the directivity is calculated by numerical integration when the aperture is smaller than 10 wavelengths on a side For electrically large apertures the usual directivity approximation of 4274 4 with the appropriate aperture efficiency is used The aperture is assumed to be located in an infinite ground plane polarized in the y direction and the radiation is assumed to be one sided This analysis assumes an equivalent magnetic current only and so does not include a 1 cos 6 obliquity factor in contrast to the horn antenna analyses Begin by entering the frequency and the E plane and H plane aperture dimensions Then select the amplitude taper using the pull down menu You may choose to have either a uniform or a cosine taper in either of the two dimensions of the aperture a TE10 waveguide mode corresponds to uniform cosine Click the Compute button to compute the patterns and directivity Pattern plots can be made in the E and H planes of the aperture or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the patte
118. umed to be centered along the width dimension The routine will then estimate the resonant frequency of the antenna and suggest a frequency step size These values are displayed along with the default number of frequency points in three boxes to the right of the Compute button Click the Compute button to accept these values for the frequency sweep or enter new values for the sweep center frequency the frequency step size or the number of frequency points The routine will then compute the input impedance of the antenna over this frequency sweep and display the results in the list box If necessary use the scroll bar at the right of the box to scroll through the list of impedances The routine also computes the approximate bandwidth the radiation efficiency and the directivity of the antenna At this point you can plot the impedance locus versus frequency on a Smith chart plot or a VSWR Return Loss plot and can save the impedance data in a data file Pattern plots can be made in the E and H planes of the patch or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation 1 Consider a rectangular probe fed patch with a length of 4 92 cm a width of 3 28 cm a substrate with a dielectric constant of 2 32 and a thic
119. ure dimensions and the axial lengths of the horn in the E and H planes The axial lengths are the distances from the imaginary apex of the horn in the E and H planes to the mouth of the horn not the slant lengths Click the Compute button to compute the patterns and related antenna parameters The routine prints out the maximum phase errors at the edges of the aperture relative to the center of the aperture the optimum aperture dimensions the directivity of the horn and the E and H plane phase centers Pattern plots can be made in the E and H planes of the horn or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button Validation 1 Consider a pyramidal horn at 3 GHz with an E plane aperture dimension of 27 5 cm an H plane aperture dimension of 55 cm and an axial length of 60 cm Results for this example can be found in 2 and are compared with results from PCAAD below Quantity Reference 2 PCAAD 6 0 Max phase error E plane 56 7 56 7 Max phase error H plane 226 9 226 9 Directivity 18 8 dB 18 8 dB Validation 2 Consider a pyramidal horn at 3 333 GHz with an E plane aperture dimension 24 cm an H plane aperture dimension of 32 41 cm an E plane axial length of 40 41 cm and an H plane axial length
120. ures of the other array routines in PCAAD A data file is used to specify element coordinates excitation amplitude and excitation phase You can specify the element type from the same selection of elements available in the other array routines Pattern plots can be made in the E and H planes of the array or E theta E phi or Co pol X pol patterns can be made at an arbitrary azimuth angle Note that E plane H plane patterns are not available when the array elements are vertical monopoles Patterns can be plotted in polar rectangular or volumetric 3 D form and patterns can be saved as data files Select the pattern type and parameters with the Pattern Type Select button The directivity of the array can also be calculated As indicated in the picture at the top left of the form the array is assumed to lie in the x y plane if a ground plane is present depending on the element type it is positioned below the array parallel to the x y plane The pattern is computed using the array factor of the array multiplied by the element factor Mutual coupling effects are not included in this routine Directivity is computed by numerical integration of the pattern which can be very time consuming for large arrays The maximum size of the array is limited to 200 elements in each dimension The element data file is selected with a file dialog box The data file should have the format of x coord in cm y coord in cm amplitude phase in degre
121. ved as default values by clicking the Save Defaults button For planar patterns you have the choice of viewing either E theta E phi Co pol X pol Ludwig s third definition or E plane H plane patterns at a particular azimuth angle E plane H plane patterns are not available in some PCAAD routines The elevation angle step size can also be specified You can also control whether or not phase data is saved with the planar pattern data to a file by using the check box For 3 D volumetric patterns the elevation and azimuth step sizes can be specified these values should generally be between 2 to 10 degrees for best results Volumetric patterns are computed using the magnitude of the total electric field and may be plotted over either the upper hemisphere or both hemispheres depending on the type of antenna You can choose to display only the upper hemisphere of a 3D pattern plot by using the check box Note that many antennas in PCAAD microstrip antennas horn antennas and antennas over a ground plane have volumetric patterns that extend only over the upper hemisphere A 7 Default Plot Colors This window is used to set the default colors used in the pattern polar and rectangular and impedance Smith chart and VSWR Return Loss plotting routines Line colors for data sets can be set as well as the cursor color and background color Color selections can be saved as defaults for later use A 8 Exit Click this option to exit

P C A A D 6.0 - Antenna Design Associates

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