A novel composite transmission metasurface with dual functions and its application in microstrip antenna

Abstract

Generally, a double corner-cut square structure transmission linear to circular polarization conversion metasurface (DCS-PCM) is difficult to realize circularly polarized radiation when it is applied to a linearly polarized microstrip antenna as electromagnetic surfaces superstrate. A novel composite transmission metasurface (NCTM) with dual functions of linear to circular polarization conversion and polarization selection is proposed and verified. For a y-polarized incident wave, transmission linear to right-hand circular polarization conversion can be realized from 8.43 GHz to 9.50 GHz, and for an x-polarized incident wave, co-polarized total reflection can be realized. Different from the DCS-PCM, the unit cell of the NCTM is made up of a corner-cut square, a substrate, and a polarization gate. Thanks to the novel design of polarization gates, the proposed NCTM is easier to realize circularly polarized radiation when it is applied to a linearly polarized source antenna. The realized gain of the antenna with NCTM can be improved because of the Fabry–Pérot resonant cavity, and the maximum amplitude of the gain improvement is 6.8 dBi. The results of simulation and experiment show that the linearly polarized microstrip antenna with NCTM can realize circularly polarized radiation with an axial ratio less than 3 dB and a significant gain improvement simultaneously.