pifa antenna design for LTE bands

hello
i want to design a pifa antenna for LTE2305 and LTE2500. I've designed antennas for these bands separately but now i want a design which consists both of these bands. what are the ways to find this sorted out. I've tried to cut slots in my design but didn't get both bands simultaneously. Plz help me.
thnx & regards

I think ur approach of Defected ground is good, but u need to try different structures to get ur results optimized..!