HFSS, whats wrong with this waveguid?

[jonny1]

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

 

[micky74]

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.

 

[shameemkabir]

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