A Wideband Low-Sidelobe Dual-Circularly Polarized Transmitarray Based on Spin-Decoupled Metasurface with Amplitude Modulation

In this paper, a wideband low-sidelobe dualcircularly polarized (CP) transmitarray (TA) is proposed based on a spin-decoupled metasurface with amplitude modulation. The metasurface merges propagation phase and PancharatnamBerry (PB) phase to independently control the cross-polarized transmission phases for left-handed CP (LCP) and right-handed CP (RCP) incident waves. In addition, interior rotation is performed within the multilayer meta-atom to induce chirality in the structure, thus introducing tailorable amplitude in the two CP channels. As a proof of concept, a dual-CP TA operated in the 5G millimeter-wave band is designed, fabricated, and experimentally verified, showcasing a suppressed sidelobe level (SLL) of −27.5 and −25.3 dB, an aperture efficiency of 31.3% and 28.6%, as well as a 3-dB gain bandwidth of 22.3% and 23.2%, for the radiated LCP and RCP beams, respectively.