file in format s2p

You have to use Touchstone format. Here you can find how to do this:
http://www.eda.org/pub/ibis/connecto...one_spec11.pdf

I can't download the pdf file, can you upload it here?
Thank you very much!

Here it is

It is very kind of you. Thank you vmuch!

i've exported the results of sonnet em simulator in touchstone format (s2p file) but it gave error when i tried to read it in matlab using read(rfdata.data,'filename.s2p')

can u help me in finding out why this error appeared? and do exported touchstone format files differs from one program to another ?!