[question] About wideband CP antenna

Hi every one,
I have to face questions in designing a wideband (from 1.2 to 2.4GHz) circularly polarized planar antenna with small size (a 4X4 square inch area).I had thought about for a few days but have no ideas:(
Would someone give me some advices or papers on it?
Thanks!
Regards!

CaoCao

Embedded narrow slots in microstrip antennas can give a circular polarization (the angle of the slot can give you LHCP or RHCP).
Using multi-resonance broadband patches can increase your bandwidth, but to make an antenna to work from 1.2GHz to 2.4GHz would be a challenge.
http://www.ece.uvic.ca/~jbornema/Con...04aps-kabs.pdf
http://www.ece.uvic.ca/~jbornema/Con...-04aps-ktb.pdf

Thanks for vfone's papers:D
On the other hand,should we design a circularly polarized antenna works from 1.2~2.4GHz with two layer and patch were stacked?
Regards!