Help With Design of Coupling Hole for X band Cavity

I have to design a one port cavity at 10 Ghz for a gunn oscillator, I used formulas to get the dimensions of a=1'' b=2" and c=1.014" for TE101 mode. Now i cant decide what should be the radius and position of the coupling hole? and on what factors does it depend?

URGENT!

OK so nobody helped. Ill still write down the solution so anyone facing the same problem can get help from it. the coupling hole has to be optimized by using the software. the basic rule is, the smaller the coupling hole, better would be the dip at the target frequency when you plot S11.