What relationship between input impedence and S11,S21,S22?
Rin=S11 + S12.S21.Rl/(1-S22.Rl)=(Zin-Zo)/(Zin + Zo) Anyway, the practical way is to download an rf app.programme(I don't remenber the name from rfglobalnet.com there you can intro de s parameters in .s2p and you can see the Zin in SChart ......