increasing bandwidth and return loss

hi
i want to improve the bandwidth and also the return loss
i have made a second iteration of koch curves n as well as seirpinski carpet. then merged together.
my ground plane is half.
n the periphery of the design is subtracted out from the ground.

please help me out to increase the bandwith , that is to cover the gsm and uwb band. and also to have return loss around -50db.
plz repli earlier