Wideband High-Gain and Low Scattering Antenna Using Shared-Aperture Metamaterial Superstrate

Abstract

In this paper, a novel wideband high-gain and low scattering antenna using a shared-aperture metamaterial superstrate (SAMS) is designed, fabricated and measured. The superstrate unit cell consisting of two frequency selective surface (FSS) layers with a positive reflection phase gradient is designed to enhance the antenna gain. Then, three different sizes of single units are arranged as a shared-aperture configuration to form the metamaterial superstrate, which is loaded onto the antenna. By utilizing the phase compensation property along different units, the antenna gain enhancement bandwidth is effectively broadened. By adjusting the SAMS loading height, the antenna radar cross section (RCS) is also reduced obviously owing to the different reflective wave phases of PRS and antenna ground. After loading SAMS, the antenna possesses an impedance bandwidth of 44.7% from 7.8GHz to 12.3GHz, covering the whole X band. From 7.9GHz to 12.1GHz, the antenna has an obvious gain enhancement, with a peak of 7dB, meanwhile, the antenna RCS is effectively reduced from 4GHz to 12GHz and the maximum RCS reduction reaches 25.4dB at 8.6GHz for x-polarized incident wave and 15.8dB for y-polarized incident wave. The results are validated by both numerical simulation and experimental measurements. Comparing with traditional fabry-perot (FP) antenna, SAMS can effectively broaden the gain enhancement bandwidth and reduce the antenna RCS, it has great application values in designing high-gain and low scattering antennas.