Thanks for your response.After going through some of the literature i got some understanding of it.But now i am facing problem in parameter extraction from scattering parameter.I tried it both in matlab as well as in HFSS but could not able to figure out refractive index n.My magnitude response,phase response,impedance plot is exactly same as the paper but problem is in refractive index n. I had attached both hfss file,matlab file and the paper which i am following.In HFSS also i had embedded expression of impedance,phase and magnitude response.Any suggestion will be of great help.I think my choice of wave vector may be wrong.Since K=(2*pi*f)/c and f is varying from 0 to 20 GHz so it is expected that K should also vary.Is it require to choose all the values of K or i require to choose the value of K at around 9.23 GHz .