hfss and discontinuity s parameters

hello
I am new in hfss.I want to extract s parameters of single step rectangular discontinuity and to compare these results with mode matching results.How i can achieve this with hfss?

Congratulations on getting HFSS :)

I'm not sure what you're describing, can you elaborate on your setup in more detail?

Hello.
With mode matching technique we can describe a discontinuity with a generilized scattering matrix(GSM).The GSM describes only the discontinuity,doesnt take into acount the connected waveguide sections. Can simulate only the discontinuity without waveguide sections before and after, can i extract only the discontinuity GSM,can for example define reference planes just before and after discontinuity and then calculate the GSM?

I'm gathering from what you told me that you're simulating some sort of waveguide with a missing section (the discontinuity to which you're referring).

Yes, you can set up a pair of waveports on the two ends of your waveguide. You can then de-embed the ports to the edges of the discontinuity, and get the scattering parameters.