How can I accurately model PIN diodes for a polarization-reconfigurable antenna at 30 GHz? I aim to excite two orthogonal modes with a 90° phase difference to achieve RHCP and LHCP. While the approach works by using RF open and short conditions in the antenna feedline, achieving axial ratio below 3 dB. For modeling of PIN diodes with RL/RLC circuits in CST results in an axial ratio of 3–5 dB (not true CP), and for more practical approach, the manufacturer's Touchstone file yields >10 dB axial ratio. Any suggestions for improving the diode modeling.
Note: I am using the touchstone file of MADP-000907-14020x (MACOM).
RLC values are also extracted based on these manufacturer data.
Hello,
It is easy to model PIN diode in CST microwave studio. First of all, two points are selected for the given GAP and the use lumped element to provide the data for RLC. Also for off and on conditions, correctly put the values for R.
Thanks.
Smrity Dwivedi Thank you for your response. As mentioned earlier, when using the lumped element approach with RLC components or even incorporating a Touchstone file, my results are not meeting expectations—I am unable to achieve an axial ratio below 3 dB. However, I am observing good reconfigurable circular polarization performance when using only an open gap (assuming the PIN diode is in the OFF state) and a short (assuming the PIN diode is in the ON state).
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