On the differential feeding technique for circularly polarized resonant antennas

The application of the differential feeding technique to circularly polarized (CP) resonant antennas is investigated in this paper. For every single-feed CP resonant antenna layout exhibiting two symmetry planes, such technique can be fruitfully implemented to get perfectly symmetrical radiation patterns around the main beam direction. Through numerical simulations relevant to a couple of single-feed circularly polarized antennas presented in the open literature, it is shown that the differential feeding technique can reduce significantly the axial ratio values in the antenna beamwidth.