folded patch antenna design

Hi all,
I am nilux.
I am working on antenna design. In this i am designing a folded patch antenna .

I am new in antenna design .
Please any body tell me is there any theoratical design formulas for designing a folded patch antenna.
and also suggest me designing formulas for microstrip patch antenna.In microstrip patch antenna i am not able to calculate the inset length and width of the patch antenna ....
Thanks in advance..
Nilux

Try this

http://www.sel.eesc.usp.br/jmo/issue...pdf/v3n3a2.pdf