design antenna for wpt

i want to design rectangular microstrip patch antenna for my wpt project....which substrate i should choose? I have already started working with FR4 for 10Ghz frequency...but performance is not satisfactory.

Try RT Duroid substrates such as 5880, 58870 ... but expensive!

---------- Post added at 12:37 ---------- Previous post was at 12:06 ----------

Just curious ... can u explain... what is WPT ...

thanks for quick reply....but im sorry to say it didnt help me since im student and can nt afford such an expensive substrates..

Which part of the performance is not satisfactory?

FR4 might be too lossy at 10GHz.

certainly FR4 would be quite lossy at 10 GHz. but as kohi noted, what is the performance parameter that isnt satisfactory? if you end up needing a material wither lower loss tangent then as suggested look at a teflon based material. if you identify a material work with your department at school to secure you a free sheet or two. this should be easily achievable.