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.
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.