[HFSS] PML and waveports

Hi to everybody.
I am a newbie in HFSS, i'm trying to simulate a microstrip filter and obtain the S parameters.
I used until now the radiation boundary conditions, but for obtaining more accurate results, I'm trying to use PML. What should I do for the faces of the airbox where there are the two waveports?
I cannot use PML on them, and there are also issues if I use rad boundary contitions where rad and PML are in touch.

Any help and explanation is appreciatd.
Thank you in advance

Hi fracar,

There should not be an issue using radiation boundaries, just make sure that they are at least one quarter wavelength away from the strip. The further away, the better.

If you really need PMLs, I would suggest putting PMLs around the air box, and using lumped ports to excite the MS.

thank you for your reply.