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In this paper, a novel design strategy for a circularly polarized metasurface antenna array that integrates low scattering and well-behaved radiation is proposed. Firstly, based on the Jerusalem cross-shaped patch, a metasurface element with 180° reflection phase difference under orthogonal normal incident waves is designed. The characteristic mode theory is utilized to analyze the metasurface element mode to excite the linear polarization radiation. Then, the metasurface antenna elements are arranged orthogonally in a 2×2 subarray and fed with a 90° phase difference, which achieves high port isolation, better circular polarization radiation and low scattering performance. Finally, the 4×4 array is fabricated and measured, and the good agreement between simulation and measurement verifies the effectiveness of the design method.

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.

The transmission polarization conversion metasurface has been widely concerned, because it has the advantage of being easy to be conformal with the antenna. Based on the reasonable arrangement of transmission polarization conversion units, various and complex electromagnetic functions can be realized. As the electromagnetic open window on the flight platform, the antenna is the bottleneck that restricts the decrease of radar cross section (RCS) of the whole flight platform. It is difficult to simultaneously realize the normal and efficient radiation of the antenna and the decrease of the RCS of the antenna. When the designed transmission metasurface is used in the antenna design, the radiation and scattering of the antenna can be regulated comprehensively. In this paper, a composite polarization conversion metasurface is proposed and verified. The unit cell of composite polarization conversion metasurface consists of two mirror symmetrical anisotropic metal patches in the upper layer, a dielectric layer and a polarization gate in the lower layer. When the polarization direction of the incident electromagnetic wave is perpendicular to the extension direction of the polarization gate and arrives at the composite polarization conversion surface, the conversion surface can realize the conversion from transmission linear polarization to right-hand circular polarization in a frequency range from 9.3 GHz to 10.9 GHz. When the polarization direction of the incident electromagnetic wave is parallel to the extension direction of the polarization gate, co-polarized total reflection can be realized. The chessboard arrangement metasurface is composed of composite polarization conversion unit and its mirror unit. A novel linearly polarized chessboard arrangement metasurface antenna is composed of the linearly polarized source microstrip antenna with a bandwidth of 9.4–10.7 GHz and the chessboard arrangement metasurface. By using the counter rotating cancellation characteristic of circular polarization, the chessboard arrangement metasurface antenna maintains linearly polarized radiation. Comparing with the source microstrip antenna, the linear polarization purity of chessboard arrangement metasurface antenna is improved from 9.5 GHz to 10.5 GHz. At the same time, the forward gain of the chessboard arrangement antenna increases and the radar cross section decreases. The maximum reduction is 39.2 dB. To further verify the practicability of the design and analysis, the chessboard arrangement metasurface antenna sample is fabricated and measured in microwave anechoic chamber with an Agilent 5230C network analyzer. The experimental results are in good agreement with the simulation results. This study has important reference value in the design of high gain, low RCS antenna and integrated regulation radiation and scattering of antenna.