I know CST does not produce S-parameters even if inactive discrete ports on antennas are used rather it produces F-parameters. It also shows RCS of the antennas as they are in receive mode. Could someone suggest any technique or tip to calculate s-parameters using plane wave excitation?
Thanks.
For the measurement of S-parameters you have to define ports. Since plane wave excitation doesn't use ports, you can use pec/pmc boundaries and waveguide ports to calculate S-parameters.
Krunal Patel Thanks for response. But on plane wave simulation with passive waveport on an antenna does not calculate s-parameters.
Muhammad Faisal Bashir Sir, If you are using waveports then it is not required to excite the structure with plane wave. Waveports themselves take care of linear polarization.
Muhammad
One way out would be computing the field amplitude of the reflected wave over the incoming wave, as the definition of scattering parameters dictates. Its a little bit tricky but I did it once (not for plane wave excitation though) and compared it against the S parameters from a waveguide port - they were similar. The "port impedance" is 377 Ohms not 50, nevertheless both are TEM-like transmission lines. Create a rectangle over your structure and sample the fields, thats it. The "s-parameters", naturally, will depend upon where your rectangle-port is located.
You have to think about how to separate the incoming vs. the reflected wave, maybe you need two projects, maybe you might use the default amplitude of sqrt (1W) the software uses for plane wave excitation. Because the pure simple sampling using the field monitors captures the whole field, incident AND reflected, theres a "directional coupler" missing in this thing.
Hope it helps.
Marcelo! thanks for understanding my question properly. In fact, I am thinking about a method to calculate open-circuit voltage induced on a receiving antenna. I guess what I understood from your method is probably to use two rectangles with waveports defined on them, one to as incident source and second as receiving source. The receiving source shall give an idea about s-parameters.
Muhammad Faisal Bashir
Actually you dont need to use waveports on those rectangles - in case of a plane wave excitation as you mentioned their surfaces will sample the incoming and reflected field, exactly as S params definition.
Marcelo B. Perotoni
Alright. Thanks for your kind input. Time for me to try and try!
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