HFSS, whats wrong with this waveguid?

Hi,

i have a problem with HFSS. I have constructed a rectangular waveguide. (4mm wide).

When i plot the S11, i have expected that the reflection under 37.5GHz is 0dB, total-reflection, because here the wave is not able to pass the waveguid.

But Hfss shows another result, which cant be true, at my opinion.
I belive something is wrong with my waveportsettings.

Maybe, somebody cant help?

thanks

No, you should not expect the return loss to be 0dB.

The input wave does not reach the other port but is evanescent so you can see a lot of loss as the wave propagates inside; however it does not return back to its own port.

mickey, you are right. if we take a look at the animated E_field along the waveguide (below cutoff), it would be clear.