A question about HFSS when simulating BPF .

When simulating filters using HFSS , I define WAVEPORT defaultly,and next time I choose the "renorm 50 ohm " ,the two results are some different .In the HELP CONTENT ,It says that when defaulted,the impedances of ports are 50 ohm ,so why are there some diffrent,
How should i define ?
thanks!

Check the characteristic impedance that that waveport module is reporting for the port Zo solution. It's possible that your port lines are a different impedance; hence the default S-paramters would be normalized (generalized S-params) to that Zo.

If you renorm the impedance, then you are converting your S-parameters from a Zo system to a 50 ohm system. If Zo is quite a bit different from 50 ohms, you will see that the results are different.

Think of it this way, you are attaching a 50 ohm load to your BPF ports instead of port Zo loads when you do the renorming.

Hope this helps,

-Max

Max
Thank you very much ,
your answer is helpful to me, previously i thought so but i am not sure about that .