Reduction of cross polarization for circularly polarized broadband waveguide antenna

An L-shaped probe can generate circular polarization, combining with surrounding aperture, such as waveguides. And such structure has broadband characteristics in both axial ratio (AR) and input impedance, however cross-polarization (XPOL) is easily generated due to its asymmetrical structure resulting in a narrow azimuth range for circular polarization. In this paper, the waveguide structure is modified to reduce XPOL generated from a circular waveguide antenna using the L-shaped probe. The proposed antenna is also fabricated and measured.