Circular polarization using 90 degree hybrid coupler

hello, Im designing a multi-band circularly polarized patch antenna in hfss. In order to achieve circular polarization, i'm using a 90 degree phase shift between two ports . however, while checking axial ratio, i am able to achieve an axial ratio less that 3 dB for the non resonating frequency while the axial ratio is high at resonating frequencies. can anyone explain the reason? also, does the positioning of feeds affect the polarization? as in, should i place the feed exactly 90 degrees apart? Thanks in advance.