Broadband receiver–transmitter metasurface with asymmetric transmission for simultaneous wideband circularly polarized radiation and low backward scattering

Abstract Asymmetric transmission of circularly polarized (CP) waves holds immense potential for a wide range of applications, including spectroscopy and optical communications. Nevertheless, state-of-the-art structures designed for CP asymmetric transmission typically suffer from a constrained operating bandwidth (BW), which hinders their widespread adoption. To address this challenge, this paper introduces a pioneering receiver–transmitter meta-atom that achieves a broad asymmetric transmission BW for CP waves. The current-cutting effect, induced by rectangular slots etched into the patches of the meta-atom, is fully harnessed to realize this broad asymmetric transmission BW, which substantially outperforms the BW performances of existing cutting-edge designs. To demonstrate its practical utility, a metasurface (MS) composed of this innovative meta-atom is subsequently designed to construct a low-scattering CP transmitarray antenna. The MS combines broadband asymmetric transmission with dispersion-free geometric-phase modulation, enabling both wideband CP radiation and wideband backward scattering suppression for the final antenna system. The proposed antenna system surpasses previously reported low-scattering counterparts by delivering a unique combination of high gain, exceptionally wide operating BWs (for both realized gain and axial ratio), and effective scattering suppression.