Hi,

I have a problem in simulating in CST Microwave Studio. The problem is mainly about how to accurately simulate the bandpass filtering chip with its S2P file in the 3D solver.

The problem is as following:

In my project, I have designed an metasurface unit lumped with the filtering chip (Qorvo, QPQ3500). Before the simulation of the metasurface, I must verify the feasibility of the simulation of the filtering chip with S2P file in the CST. So, I have constructed a simple microstrip line model in the CST Microwave Studio and tried two different simulation methods.

The first method is to directly construct a multipin lumped element and choose the s2p file of the filtering chip. And the whole simulation is conducted in the 3D solver.

The second method is to construct another two discrete ports, and the s2p file of the filtering chip is loaded in the schematic of the model. And then the EM-Circuit co-simulation is carried out in the schematic view.

Different results are obtained from the two methods. As shown in the figures, the S11 results of the two methods agree well with the original data. However, the S21 results of the two methods does not show good agreement with each other in the pass band. It can be seen that the S21 results of the EM-Cir Cosim agrees perfectly with the original data. But the S21 results of the Multipin shows at least 2 dB reduction in the passband, which is far beyond our expectation.

So, how can we accurately simulate the filtering chip in the 3D solver with the Multipin lumped elements?

PS: for some reasons, the EM-circuit Cosim in not considered in our further simulation of the metasurface, so we urgently want to know the tips of simulate the filtering chip accurately in the 3D solver with the Multipin lumped elements

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