A Low-Cost, High-Efficiency and Full-Metal Reflectarray Antenna With Mechanically 2-D Beam-Steerable Capabilities for 5G Applications

This article presents a low-cost, high-efficiency, and full-metal reflectarray (RA) antenna with mechanical beam-steerable capabilities. A unit cell (UC) implemented by a metal cylinder with a cuboid-shaped notch is proposed to achieve a 1 bit reflection phase (0 and π) for the transverse electric (TE) and transverse magnetic (TM) normal incidence waves. The proposed UCs can be employed to construct an RA antenna with 2-D beam-steerable abilities. For demonstration, the RA antennas with six different beam directions are presented as examples, by simply adjusting the rotations of the UCs. The impedance matches of the RA antenna are all below -10 dB from 22 to 33 GHz, and the measured radiation patterns of the RA antenna are all highly consistent with the simulated counterparts for the six different beam direction scenarios. A 1.5 dB gain drop bandwidth of approximately 20% from 24.7 to 30 GHz and a peak realized gain of 18.9 dBi at 26 GHz are experimentally obtained for the RA antenna with radiation patterns at broadside. Compared to the substrate-based UCs loaded with p-i-n diodes, the proposed UCs have full-metal structures without using any active RF components and dielectric substrates, leading to the high total efficiency of the proposed RA antenna. Due to the low-cost, high-efficiency, and high-power handling properties, the proposed RA antenna can provide a fixed or scanning beam and is a good candidate for 5G millimeter-wave communication applications.