Gain of uwb antenna with notch band

hi everyone!
i have designed a uwb antenna with a wlan notch band..
i am experiencing problems with the gain..
please suggest what changes in the design may prove helpful to improve the gain of my antenna..im attaching the pictures of my design and the gain of the design..
it is a cpw fed antenna with u-shape notch in transmission line.
Treat it as urgent please..:)

slotted antennas tend to have comparatively less gain due to bandwidth enhancement and size reduction.