RF ports in a CPW in COMSOL

Hi,

I'm a beginner with COMSOL Multiphysics.

I need to simulate a coplanar waveguide, but I don't understand how to define rf ports.
On the model library, there are few examples of easy structures (microstrip, coaxial cable) but nothing about a CPW.

Taking in account the port definition of these structures, I think RF port have to be defined in the area between the rf conductor and the ground. So for the microstrip, I have to define a rectangle between the line and the back plane, and for the coaxial cable, port will be the area between the central conductor and the external ground.

But for a CPW? I tried to define some areas, but I didn't have any propagation in the CPW.
Do you have any ideas?


Thanks a lot