Dual-Band Shared Aperture Multimode OAM Multiplexing Antenna Based on Reflective Metasurface

Compared with conventional planar electromagnetic waves, vortex electromagnetic waves carrying orbital angular momentum (OAM) are unique beams with a helical phase structure and a toroidal amplitude field. Due to the infinity of OAM modes and orthogonality between different modes, a completely new degree of freedom independent of time, frequency, and polarization domains is provided. OAM waves have great potential in terms of channel expansion and improving spectral efficiency. And with the progress of research, how to transmit more information and have more channel capacity has been a hot issue. In this paper, a novel single-layer dual-band orbital angular momentum (OAM) multiplexed reflective metasurface array antenna is proposed. We firstly design a metasurface that can realize dual-band nearly 360° phase coverage at 7 and 12 GHz, and realize 2-bit coding metasurface cells by obtaining suitable geometrical parameters through simulation optimization, and then we obtain the position of each cell in the array away from the feed source by computing. Afterwards, the corresponding phase compensation and the phase gradient required for specific mode OAM beam generation are calculated from the position of each cell in the array, and a 30×30 reflective metasurface array is obtained, which can independently generate different modes of OAM beams in the C and Ku bands, and complete flexible beam control in each operating band, providing a new possibility for realizing more transmission frequency bands and larger channel capacity in communication applications.