Circular polarization using coupler

hello,
i'm designing a patch antenna in hfss. in order to achieve circular polarization i'm planning to use a 90 degree hybrid coupler. Is it possible to create a 90 degree phase shift in orthogonal mode excitation in hfss without actually having to draw a coupler. thanks in advance.

Hi gayathrim,

Yes, it is possible. Using either lumped ports or wave ports, you can set the sources excitation phase under "HFSS"->"Fields"->"Edit Sources...".

Good luck!

I tried that. I used two lump ports positioned 90 degrees apart and sources changed to phase 0 and 90 respectively. however, i'm still not able to achieve an axial ratio vs frequency below 3 dB for resonating frequencies.

Unfortunately, the issue is then your antenna, and not the excitation. Is it a circular patch?

yes, it is. and the axial ratio at non resonating frequencies are less that 3 dB. but at resonating points, greater that 15dB.

Also, since there are two ports, which return loss should we consider? s11 or s22? or the resultant?