Low-RCS Beam-Steering Antenna Based on Reconfigurable Phase Gradient Metasurface

A beam-steering antenna with low radar cross section (RCS) based on a reconfigurable phase gradient metasurface (PGM) is proposed in this letter. The PGM loaded with p-i-n diodes is designed as a tunable radome to steer the beam, improve the gain, and reduce RCS of the antenna in a wide operation band of 4.2-4.55 GHz. The beam directions of 0°, ±7°, ±15°, and ±23° (at 4.4 GHz) can be switched. Moreover, the PGM focuses the beam of the antenna and scatters the electromagnetic wave incident to the antenna. Thus, the gain can be increased by 3 dB approximately, and the RCS of the antenna is effectively reduced simultaneously. A prototype of the antenna is manufactured and measured. Simulated and measured results have a good agreement, which verifies the performances of the antenna with the active PGM.