A flexible linear circular bipolarization conversion metasurface based on graphene

Abstract

A flexible bipolarization conversion metasurface based on graphene is proposed in this paper, which can achieve single-band linear-to-linear (LTL) and dual-band linear-to-circular (LTC) polarization conversion. The polarization conversion ratio (PCR) and axial ratio (AR) are dynamically regulated by varying the sheet resistance (R_s) of graphene. When R_s = 1400 Ω Sq⁻¹, the designed metasurface achieves a single-band LTL polarization conversion of 7.47–12.38 GHz (PCR > 90%) with a relative bandwidth (RBW) of 49.47%. Meanwhile, dual-band LTC polarization conversion is realized in the ranges of 6.25–7.28 GHz (RBW = 15.32%) and 13.01–26.71 GHz (RBW = 68.98%) with an AR of less than 3 dB in both bands. Furthermore, broadband and high-efficiency performance in LTL and LTC polarization conversions can be maintained over a wide range of incidence angles. The physical mechanism of the LTL and LTC polarization conversion is explained by the admittance model and is further discussed by employing the surface current distribution. Especially, the proposed design is used to achieve radar cross section (RCS) reduction. More than 10 dB RCS reduction is realized in the range of 7.54–12.33 GHz (RBW = 48.21%). The capability of bipolarization integration with LTL and LTC polarization conversion into a single structure possessing high-efficiency, broadband and flexibility characteristics has potential applications in wireless communication, radar/satellite detection and remote sensing.