patch antenna gain enhancement

i have designed a suspended patch antenna with a material having a dielecric constant of 3.2 substarte height 0.762 mm and loss tangent of 0.004 the height of air is 3mm below the substrate i am using microstripline feed now i cant seem to enhance its gain beyond 8 db .please tell me how can i improve my gain .i am new please tell me what dielectric material should i be using i would appericate suggestions on that my antenna is designed to operate at 10 Ghz

With other sustrate you could chane gain but not very much. More gain increasing directivity.
Add a ground plane as reflector and directors , and if you need more gain you must think in parabolic reflectors.

If size isn't a problem for you try to build some patchs (not feeded) working like a directors, increasing your gain in desired direction.

Hello

You can use Metamaterial structure (as superstrate) over patch to enhance its gain, If u search in www, u will get more review papers related to metamaterial over patch antenna.

regards
Avinash

8 dBi is pretty good for a patch. If you want more gain you might look into an array of several.

Sometimes a bigger ground plane will help. Small increases are possible with more efficient materials or improvements to the impedance matching.