Hi Sassyboy,
Thanks for your nice answer. You have outlined rather nicely the standard design procedure. What I actually meant was the resonant impedance at the edge, that is without any inset. From your simulations it is okay to say that for the given return loss the p@tch is correctly matched to approximately a 45 ohm line ( neglecting the imaginary part and assuming that you tune inset to get rid of that ). Now if the resistance without inset is R0 then we have Rinset=R0*cos²(Π*x/L) (Balanis) where L is the length and x is the inset. Now substituting the values you have got by simulation, we get R0 to be around 1200 ohms. This was what I wanted to know , how this R0 depends on the permittivity of the substrate. Normal quoted values in the papers ( low permittivity substrates ) is about 100-350 . So I am a bit surprised at such a high value. Anyway thanks a ot for the simulation result thus reconfirming my design.
-svarun