Multibeam Metasurface Antenna Based on Orbital Angular Momentum Modes
Demultiplexing Feeding
Abstract
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.