Waveguide Wave port issues HFSS

As part of a bigger project I am using a grounded CPW for a SIW in HFSS. I simply want to start with just making sure the CPW part works first before proceeding with the rest of the project so using a calculator I got the dimensions needed for a 50:addSymbol('937')" target="_blank" rel="nofollow">Ω characteristic impedance and proceeded to create my design. The issue that has me stumped involves the wave ports. I found the recommended dimensions for the rectangle but it throws an error for the wave port not being backed by a pec. I tried making my ports into thickened rectangles and assigned the excitations only to the faces facing into the waveguide and got no errors however looking at my S parameters I could tell I was not getting the correct results. Does anybody have any advice as how to fix this issue?

I am running modal simulations, the conductor is copper. I can provide any additional details as needed to find the solution.

Welcome TheXander,

Extend the CPW to the edges of the simulation domain, and apply the waveports there. Then, they won't need to be backed by a PEC.

Thank you for the reply. It is quite helpful to me. I have simulated a similar CPW device with waveports in Modal solution type. I set a rectangle the wave port. And I have a air box for radiation boundary with size lambda0/2, but the air box must touch the wave port, then touch the CPW and substrate under it. I wonder It is correct or not. thx~

That sounds correct, yes.

Good luck!