question about S-parameter in ADS

hi everyone

I have found that all *.snp files which you import to ADS,ports' impedance are all 50ohm.For instance,I export a *.s3p file of waveguide power divider in HFSS without renormalizing solution.Then I import it into ADS,and set Terms' impedance 50ohm,so I can get the same result in HFSS.If I set Terms' impedance to waveguide impedance(no matter Zpi,Zpv or Zvi),it is not correct.If I export the *.s3p file to ADS with renormalizing solution(50ohm),I can not get the same result in HFSS.So my question is why it becomes 50ohm system in ADS? and how to simulate waveguide ports' mismatch in ADS using *.snp?

best regards
Kezman

I don't know exactly what HFSS exactly do when renormalize the solution. what I can tell you is that these files have standard format, Touchstone, and in the first row you have the declaration of what is inside:
R 50 MA Hz (don't remember the exact order, edit one of your files and see it), so the files contain data referred to 50 Ohm, in magnitude and angle and frequency is expressed in Hz.
Comparing the two results you obtain, you can understand better.
I hope it can help.
Mazz

Kezman:
As far as I know, export the *snp file without renormalizing slution is right for your simulation. In hfss, if you are doing a waveguide simulation ,it's better not to
renormalize the slution because the model you are simulating may have some other mode;while if you are doing a microstrip line simulation, it doesn't matter whether renormalization or not.

When the *snp file is imported into ADS, I always set term impedence to 50 Ohm and you'll get the same results in hfss.

Good Luck

LTCC

Thank you Mazz and LTCC!Another question,why I can not import *.snp files(n>=3) ,which are exported from HFSS ,into ansoft designer?But *.s2p can do it. Because of its' format?

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