Broadband circularly polarized filtering patch antenna based on metasurface

Abstract

AbstractIn this paper, a single‐fed broadband circularly polarized (CP) filtering patch antenna based on metasurface is proposed. It consists of a corner‐truncated square patch, a nonuniform metasurface, and a U‐shaped strip. By placing the metasurface above the driven patch antenna, a radiation null is realized at the upper band, and an additional axial ratio (AR) minimum is simultaneously generated to enhance the CP bandwidth. Besides, two more radiation nulls are achieved at each side of the band edges by introducing a U‐shaped strip underneath the patch and embedding a shorting pin into the patch, which further improves the frequency selectivity and suppresses the radiation level. Measured results show that the designed antenna has a wide impedance bandwidth of 19.7% (4.8–5.85 GHz), a CP bandwidth of 19.9% (4.75–5.8 GHz), and an in‐band average gain of 7 dBic with suppression level of more than 18 dB at out of band.