Dual Circularly Polarized Fabry–Perot Resonator Antenna Employing a Polarization Conversion Metasurface

Abstract

A dual circularly polarized (CP) Fabry-Perot (FP) resonator antenna is presented in this paper. A linear to circular polarization conversion metasurface (MS) is employed as the superstrate of the FP resonator antenna. The working principle of the unit cell adopted by the MS enables it to independently control the transmission and reflection characteristics. Firstly, the MS is designed to present high reflectivity to ensure the high gain of the FP resonator antenna. Then the capability of polarization conversion is endowed to it. The square patch of the unit cell can receive two orthogonal LP waves, and the cross slot on the ground plane can also make them get through. Meanwhile, the circular patch with 45° tilted etched slot can radiate different CP waves when excited by different LP waves. Therefore, the proposed MS can combine the function of partial reflection and transmission polarization conversion. And for different LP waves, the MS can convert them into different CP waves. A dual LP microstrip patch antenna is designed to act as the feed of the resonator antenna. When the antenna is fed at different ports, different LP waves are excited in the resonant cavity and are converted into different CP waves by the MS, thus the antenna obtains dual CP radiation. The measured results indicate that the antenna can exhibit excellent dual CP radiation characteristic. Compared with other reported dual CP resonator antennas, the proposed antenna can obtain well performance with simple structure and low profile.