phase characteristic in UWB antennas

Dear All,

I'm looking for phase characteristic correction (linearization) in UWB antenna design (especially planar ones). anybody can help me finding resources over this task. I've searched IEEE and there are few papers regarding this subjest and none of them is enough for me.
I want to know how to keep the phase linear from start to end of design or if I can correct the characteristic even after the design completed and swr, BW and performance reached good lelvels but phase needs more.

Thanx in advance