Axial-Ratio Beamwidth Enhancement of Circular Polarized Microstrip Antenna Using Periodic Conducting Structures

A circularly polarized microstrip antenna with a series of conducting structures and a ground slot is proposed in this paper. The series of conducting posts enhances the 3dB beamwidth and axial ratio (AR) value, but the AR beamwidth is limited. The introduction of a ground slot enhances the AR beamwidth with minimal alteration to the 3dB beamwidth. The proposed antenna has a uniform 3dB beamwidth at all azimuth axes greater than 130 degrees, and the AR beamwidth is also uniform up to 86 degrees. The introduction of a ground slot in the antenna design resulted in a 60 percent improvement in the axial ratio AR beamwidth.