Wideband circularly polarized, slot antenna array loaded with metasurface

Abstract

AbstractThis article presents the design and measurement results of a novel wideband circularly polarized 2 × 2 slot antenna array loaded with a metasurface layer. The proposed array exploits circularly polarized elements. Each element is sequentially rotated and fed with an appropriate phase difference to ensure the generation of a circularly polarized wave. The use of metasurface enlarges the impedance bandwidth of the antenna by creating an additional resonance. The metasurface layer also improves the axial ratio bandwidth of the array. Its other major benefit is mitigating the beam squint in the higher frequency band without sacrificing the axial ratio (AR). A prototype of the antenna is built and measured in an anechoic chamber. The measured impedance bandwidth (|S11| < −10 dB) of the array is 66.7% (from 1.6 to 3.2 GHz) and its axial ratio bandwidth (AR < 3 dB) is 63.8% (from 1.6 to 3.1 GHz) which are outstanding numbers compared to the current state of the art. The measured radiation patterns of the antenna array are stable across the band of interest with a gain of >4 dBi. The overall size of the antenna is 170 mm × 170 mm.