Which substrate to use for integrated antenna and microwave circuit?

Hi all!

I have to design a planar antenna and microwave power amplifier integrated on a "single substrate". My design frequency is 2.45 GHz. Which substrate would be better:
Fr4 Epoxy (4.4) or Rogers RT Duroid 5880 (2.2) ?

Your kind help is highly regarded. :)

Rogers Duroid is certainly better for 2.45 GHz

hi hsnum
the Er may change at 2.45Ghz if using FR-4.

Thanks jiripolivka and Tomsin yin. :)