Circular patch antenna: please help !!

Hello all,

I'm designing a circular patch antenna. I've calculated the dimensions of the antenna using the equations. when i tried to simulate it, it didn't work. I'm think i have problems with the fed (coax) and the boundaries. attached is my design. it is supposed to resonate at 7.5 GHz.

can anyone please help me and tell me what should I do?

thanxxxxxxx

Added after 4 minutes:

your dimensions of this antenna does'nt real or true and your exitation have not meted in centre of cercle I think of this simulation not correct