Ka-Band Low-Profile Circularly Polarized Liquid Crystal Folded Reflectarray Antenna

A low-profile circularly polarized liquid crystal (LC) folded reflectarray antenna operating at 30 GHz is proposed. The antenna consists of a 16 × 16 LC reconfigurable main reflector, a multilayer metasurface sub-reflector, and an integrated linearly polarized feed at the center of the main reflector. To verify this design, the proposed antenna has been fabricated and measured. It features a low profile height of only 2.5λ0 with an H/D ratio of 0.31. Its beam can be continuously steered, covering ±45° in the elevation plane and 0°∼360° in the azimuth plane. The measured 3-dB axial ratio bandwidth is 9.3% (28.6- 31.4 GHz).