A Passive Multibeam Metasurface Antenna

Recently, the mode conversion capabilities of meta-surfaces have been exploited to design cylindrical vector (radially-polarized) beam antennas, and orbital angular momentum (OAM) antennas. Motivated by these developments, we use mode-converting metasurfaces to design passive MIMO metasurface antennas. The MIMO antenna consists of a mode-converting metasurface atop a rectangular cavity that is fed by multiple waveguides. The metasurface itself comprises a cascade of electric sheets separated by dielectric spacers. The impedance profiles of the electric sheets are optimized such that each waveguide feed excites a specified beam. The excited beams are orthogonal to ensure isolation between the feeds. Furthermore, the proposed MIMO antennas can be used to design future MAB (multiple azimuth beams) SAR imaging systems.