Influence of wave port dimensions on reflection characteristics - HFSS

Hi Edaboard community,

I am trying to simulate a homogeneous CPW structure using HFSS and for exciting the quasi TEM mode of this structure, I am defining wave ports at the ends of the structure.
I have computed the Poyiting vector at the surface of the wave ports; and I notice that the value is not always the same and that for certain frequencies I cannot get an indicent power larger than 0.80 Watts. (From what I understand HFSS excites every mode with a 1 Watt across the defined wave port area)

I would like to know what is the influence of the wave port dimensions on the reflection between the exciting wave port and my structure.

Both wave ports (ends of my structure) are identical and I would expect for this type of simulation, S11 parameters in the range of -20dB and that the transmission characteristics of my structure (CPW with finite ground planes) would be primarily influenced by the losses of the medium.

I would appreciate if anyone could help me to verify the reflection effects between the exciting structure (wave port) and my 3D CPW structure.

Any comment or feedback, will be appreciated

It sounds like your line is not (impedance) matched to the port. For sure, the size of the port will affect its impedance. Ensure that the wave port is sufficiently large to encompass the bulk of the modal fields. You can also specify a port mesh refinement under the analysis setup options -- I think the default is 2%, but I usually set it to 0.1%.