Measuring S21 between two waveports in HFSS

[domdro]

Hello ,

I am an HFSS beginer. I'm especially interested in waveguides simulations.
I have a question.
Let's say I run a simulation which models a WR90 waveguide , connected in serie with a WR75 waveguide , via an adapter.
I want to measure the S21 between the two ports. One port is a WR75 , the other one is a WR90 , so they have a different impedances.
When I apply waveports on both ports , and I do S21 , what happens?
Ideally both ports should be matched with their own termination ( so not the same on WR75 versus WR90). Is HFSS working this way?
Thanks for any help
Dom

 

[domdro]

Re: HFSS question

Hello ,

sorry but it is not true. Air impedance is 377ohm. waveguide charactéristic impedance depends on waveguide dimensions. The proof is that an open waveguide shows SWR.
My question is : how does HFSS behaves when S21 is computed?
In a circuit simulator , the 2 ports simulated is loaded with 50 ohms . If the 2 port is designed for a different load and generator impedances , we have to tell the simulator to use different values for input and output.
I have no idea how this is done on hfss.

Dom

 

[shameemkabir]

Re: HFSS question

waveguide port is generally matched. So, when you look at the S21 is such a case, you are watching insertion/transmission loss of the network considering both ports are matched.