Patch antenna for 2.5-2.7 GHz range.

Hello everybody. I'm designing a patch antenna for 2.5 - 2.7 GHz range using fr-4 substrate with thickness less then 3.2 mm. So far I haven't done with bandwidth more than 4-5%. Maybe someone could help me to find papers or whatever. Any help would be great

make different size patches?

I've already tried this, but i could not get two resonances close enough. Got good results only with thick substrate about 7-8 mm

Yes it`s true. Better bandwidth are with air gap and normal dimensions ( electrical dimensions equal to physical ) . Also possible some multi path, four for instance. It will be better.

Thanks everyone