A Lightweight Circularly-Polarized Waveguide Slot Antenna for K Band Satellite Communications

In this paper, a lightweight circularly-polarized waveguide slot antenna array with high efficiency and low axial ratio is demonstrated. The proposed antenna contains a rectangular feeding waveguide, which connects to a radiation cavity through coupling slots. Owing to the unique feed structure, an equal amplitude but opposite phase excitation is generated between adjacent coupling slots, making the metal walls in the rectangular radiation cavity unnecessary. Moreover, a metasurface-based polarization convert chamber is loaded onto the radiation cavity, resulting in an excellent circularly-polarized radiation. The proposed antenna works in K band (center frequency is 21 GHz) with the impedance bandwidth as well as the axial ratio bandwidth is 5.2% and 7.1%, respectively. In addition, the design of the proposed antenna has a remarkable effect on reducing the weight, showing a great potential for satellite communications.