Hi,

I have a problem in simulating in CST Studio Suite. The problem is mainly about the EM-Circuit Co-simulation, the excitation of plane wave in the schematic.

The problem are as following:

In my project, I reform a model, which is a dual-polarization patch antenna fed by two microstrip lines.

In my design, I set two discrete port at each microstrip line, and I import an S2P file of a diode with the “on” state in the schematic view. Then in the schematic, I connect the two discrete port of the microstrip lines with the imported S2P file of the diode.

In my simulation, I want to see the scattering pattern of this structure when it is under the excitation of plane wave. Theoritically, when this structure is excited by the x-polarized EM wave, the scatter the y-polarized EM wave.

PS: The patch antenna can receive the x-pol EM wave and the received EM energy can go through the diode and be reradiated in y-pol according to our design.

To realize this goal, I use the method of EM-Circuit Co-simulation and excite a plane wave in the schematic view. The settings are as follows:

In the 3D view, I define the plane wave and activate the option called “superimpose plane wave” in the 3D solver. Then I create a dummy port on the schematic. Then I start a true transient simulation from the schematic.

However, the results are not satisfying.
First, the plane wave is indeed excited in our simulation. However, the fairfield results(cosim Trans) in the 3D is more like the radiation patter of the plane wave but not the scattering pattern of our structure.

Second, from the surface current (cosim Trans), it is obviously that the two microstrip lines are not connected, which means the imported S2P file of diode are not considered in the co-simulation.

For further consideration, I also start an AC Combine task in the schematic. And the farfield result(AC Combine) and the surface current (AC Combine) show nothing(it means we can see nothing in the 3D view, all of these results are “zero”).

So, is there anything wrong in my simulation settings? Or, if I want to see the scattering pattern of this structure in this situation, what should I do?