Design of wideband circularly polarized horn antenna for millimeter wave applications

In this paper, a millimeter-wave (mmW) wide band right-handed circularly polarized (RHCP) horn antenna is designed based on a polarizer with two 90 degree slots loaded on the inner wall of a circular waveguide. The antenna is fed by a standard rectangular waveguide WR-10 waveguide port, and the antenna excitation signal is converted from linear to circular polarization by a circular polarizer. The principle of the antenna is analyzed, the model is simulated and the parameters are optimized, and the design method for obtaining the left-handed circularly polarized (LHCP) antenna based on the RHCP antenna is given. The simulation results show that the reflectance of the antenna is not higher than -24.5 dB, the RHCP gain is greater than or equal to 13.0 dBi, and the axial ratio (AR) is not higher than 3 dB in the range of 84-110 GHz (26.8% relative bandwidth). The proposed antenna is broadband and circularly polarized, and can be widely used in broadband mmW applications.