Low-Profile Circularly Polarized Liquid Crystal Folded Reflectarray Antenna

A low-profile circularly polarized liquid crystal (LC) folded reflectarray antenna working at 30 GHz is proposed. The antenna is composed of a lower planar main reflector, an upper sub-reflector, and an integrated feed at the center of the main reflector. The profile height is only 2.5 λ0 with H/D ratio of 0.31 and its beam can be steered continuously, covering ±45° in the elevation plane and 0~360° in the azimuth plane. The 3-dB axial ratio bandwidth is 8.3% (28.4-30.9 GHz).