Wideband Circularly Polarized Horn Antenna Exploiting Open Slotted End Structure

In this letter, a compact circularly polarized horn antenna is presented. By cutting a slot along the 45° direction at the end of the circular waveguide, the proposed antenna achieves the wideband circularly polarized radiation. A prototype working at W-band is fabricated. Both the impedance bandwidth (S(1, 1) <; -10 dB) and the circular polarization bandwidth (AR <; 3 dB) of the processed antenna are measured as 37.8% (75-110 GHz). The proposed antenna exhibits a simple structure, and it is easy to design, so it can be extensively applied in millimeter-wave (mm-wave) and submillimeter-wave systems.