reduce dimention of microstrip antennas

Hi everybody

I have two question to ask you.

1.How to do reduce dimention of microstrip antenna?

2. I simulated microstrip antenna and result(S11) so well.but farbricate it for test.S11 was shift frequency from 2.4 to 2.6 GHz.Why and improve it better.

pls tell me.

pd. I made microstrip antenna (rectengular),f=2.4 GHz,er:FR-4=4.4,thickness=1.6mm,width line = 3mm