bandwidth in a truncated corner antenna

I'm designing a truncated corner antenna with only one feed and circularly polarized in HFSS. But i haven't got good good bandwidth and the VSWR isn′t in the same frecuency exacticly. I've heard i can improve the bandwidth using a biger thickness or increasing the dielectric constant value, is it true?
I haven't found a theoretical explanation yet.
Somebody hekp me.

thanks in advance

How do you define your good bandwidth?
For microstrip 20 to 30 MHz is a great bandwidth.So you can look for the attached paper.It resonates at 911 and BW of 23 MHz.

Added after 1 minutes:

I am sorry
The paper is attached at the link
https://www.edaboard.com/ftopic285245.html
The post by me and the name is "half of soln.pdf"

Yes true (both of them ) but if bandwidth still is not enough, try to use slotted versions.