Phase-only polarization conversion metasurface for low-sidelobe and high-gain metalens antennas

In this paper, a metalens antenna which based on a single-layer polarization conversion metasurface (PCM) is proposed for sidelobe level suppression. The parameters of the units are tailored to regulate the propagation phase of the PCM. By combining the optimization algorithm and the phase compensation theory, the ideal phase distribution is obtained to control the wavefront, enabling the low sidelobe level (SLL) metalens antenna to realize the desired property. The metalens antenna utilizes a linearly polarized open-ended waveguide as the feed source, and the gain is improved from 7.06 dBi to 22.3 dBi at 11.5 GHz with the aperture size of 9.2λ0 × 9.2λ0. The peak realized gain of the proposed metalens antenna is 22.3 dBi, and the SLL lower than −22.87 dB in xoz-plane and −19.05 dB in yoz-plane, respectively. Compared with the reference metalens antenna, the proposed metalens antenna realizes 5 dB SLL suppression. In comparison with the existing methods for the low SLL, the method proposed herein only needs to control the phase of the PCM units, which reduces design complexity by eliminating amplitude control of designing low SLL metalens antenna. The proposed phase control method for SLL reduction is promising for wireless and satellite communication.