Dual-band dual-circularly polarized and orbital angular momentum multiplexed reflectarray

In this letter, a dual-band dual-circularly polarized (CP) orbital angular momentum (OAM) multiplexed reflectarray (RA) is proposed, capable of generating vortex electromagnetic beams with distinct polarizations, mode numbers (<i>l</i>), and radiation directions across different bands. First, it presents an innovative approach to achieving dual-band dual-CP decoupling. Second, the proposed RA integrates multiple multiplexing techniques, including frequency, polarization, and OAM. Specifically, a low-profile metasurface unit cell is designed, utilizing only a dielectric substrate and a metal patch, achieving a bandwidth ranging from 10.6 GHz to 18.1 GHz (52.2%). Furthermore, an RA constructed from these units fulfills the duplex communication requirements of Ku-band satellite systems. It generates a left-handed CP OAM beam with <i>l</i>=+1 in the downlink band (10.7-12.75 GHz), and a right-handed CP beam with <i>l</i> = -2 in the uplink band (12.75-18.1 GHz), with each beam exhibiting a distinct radiation direction.