input impedance at the edge of microstrip patch

Hi
can any one help me out in finding the input impedance of a square microstrip antenna at the edge of the patch ?any tool or formula ?
i m designing antenna at 11 GHz for which i cant use the inset feed of 50 ohms (3mm) becuse the length of antenna decreases from 9 mm .But for inset feed of 50 ohm the length should be greater than 9mm(3mm of inset feed and 6mm of the space ,3mm at each side)....
As there any other way for feeding other than quarter wave transform ?
Thanx in advance.......

See if you can find someone with a copy of Antenna Theory by C.A. Balanis. In the 2nd edition, it's chapter 14, section 14.2.1. Use Figure 14.9 to get G1 from W/lambda0. Then use Eqn 14-17 to calculate Rin (resonant input impedance), using Eqn 14-18a to calculate G12.