How to define ports for a SIW transmission line in HFSS?

I'm going to simulate a simple SIW transmission line in 60 GHz and compare the loss with other transmission lines. could you please someone tell me how should I define ports for siw? I already define it as wave ports and put a radiation box (like for microstrips) but the results don't seems correct. S11 is much higher than it would be expected.

upload your model, I can check for you.

The integration line (direction of the E-field), should be stretched between the upper and lower layers of the substrate - that will enforce the correct mode at the ports. It's hard to say any more without more information.

Attach ur results along with ur model..!!