Why circular polarized patch have wider bandwidth?

On a same substrate, why circular polarized patch have wider bandwidth than simple patch antenna? I use patch with trimmed edges, single fed. Bandwidth is around 5 times better for circular polarized antenna ( 200mhz vs around 1ghz for s11 of -6dB) at x-band.

Interesting if the observation holds us. I am not aware of anything that would increase the bandwidth. You may have the two linear polarizations tuned to slightly different frequencies giving an appearance of wider bandwidth. Is the patch square or rectangular? I would suspect slightly rectangular.

Exactly same substrate and conductor losses?
What is the difference in gain or radiation efficiency?