complex S-parameter calculation in HFSS

You could use the real() and the imag() function. With this you can create the S11* and the others.

hi flanello
could u give me more explannation about using the real and the image function?

When you right click on Results->Create Modal Solution Data Report-> Data Table->Function.
The re() and im() function give you the real and the imaginary part of a value.
With the following you get the S11*
(cmplx(re(S(1,1)),-im(S(1,1))))