In this paper, the design and implementation of an multibeam metasurface antenna with multiple independent channels using orbital angular momentum (OAM) demultiplexing feeding are proposed. Several aperture phase distributions that convert incident vortex beams with different and orthogonal topological orders into designated directional pencil beams are acquired and superimposed to form a metasurface aperture that, under excitations of vortex beams with multiple orders, produces independent multibeam each with a predefined direction. For implementation, a transmissive metasurface working at 5.15 GHz is designed with four beams pointing at arbitrary half space directions corresponding to incident vortex beams of order +1, −1, +3 and −3 respectively. Techniques such as OAM modes spacing and aperture partitioning are also utilized for reducing sidelobe levels (SLLs). Furthermore, a similar multibeam metasurface antenna with additional linear-to-circular polarization conversion function is proposed, which opens the possibility of utilizing different polarizations on top of the OAM based multibeam. The proposed multibeam metasurface antenna based on OAM demultiplexing feeding provides a low-cost solution for independent channels multibeam realization compared with phased arrays and realizes flexible multibeam directions compared with multibeam antennas based on lenses or reflectors.
