A Ka-band High Gain and Broadband Circularly Polarized Horn Antenna

In this paper, a Ka-band broadband and high gain circularly polarized (CP) horn antenna based on double-corner-cut square waveguide is proposed. By exploiting the transition from rectangular waveguide to the double-corner-cut square waveguide, the linearly polarized wave can be transformed into two orthogonal linearly polarized waves with different propagation constants. Besides, a phase-lag of 90° and a low amplitude difference between two orthogonal linearly polarized waves are achieved by optimizing the parameters of the double-corner-cut square waveguide. The CP horn antenna exhibits a 3 dB axial ratio bandwidth of 33.2% (28.6-40 GHz) and an impedance bandwidth (reflection coefficient less than -20 dB) of 40.6% (26.5-40 GHz) while the gain is 16.5 ± 1.2 dBi in the whole impedance bandwidth.