how to design circular microstrip antenna for circular polarization

hello guys im doing my final year project.and im doing circular patch antenna for circular polarization..what seem to be the problem is that i want to know how to make it circular polarization because most of example available is for rectangular shape can anybody help me by telling feeding method or any physical dimension adjusting that can be done?any helped link also great.im using cst software

Circular shape patch antenna doesn't have circular polarization.
You have to cut some slots inside of the circle to get circular polarization (see the picture).

what do you mean Circular shape patch antenna doesn't have circular polarization?i read about making the narrow slot.how to make the slot?is there any calculation?or im just cut it?how about the feeding method? very nice of u to reply my question

Standard circular shape patch antenna have linear polarization. So, you can get H or V polarization depending where the feeding point is placed.
Only using slots can get circular polarization. The slots dimension (length, width, etc.), depends by material used. The slots affects not only the polarization, but also the antenna impedance.
http://www.jpier.org/PIERL/pierl04/08.08050203.pdf

im never heard about H n V polarization...my *** its look very dificult... is there any simple way?what is advantage of circular patch compare to rectangular?..sorry for asking 2 much

Hello,

Have you tried to simulate the antenna? For example, this software separtes between right and left circular polarizations.

Dear Vfone
Kindly, thanks for your support our quistion and I need your help for circular microstrip analysis specially for Qrad & Qc & Qd & another parameter because I have problem when calculate these values.
Thanx and your supoort

please your comments and solution for these equation in attached

which eq OK for Qrad
your support please

Here you have an example using a microstrip spiral.