Design of a Dual Polarized Metasurface Antenna in Ka-Band

This contribution proposes the complete design for a dual-polarized metasurface (MTS) antenna based on the idea of duplexing an inward and an outward surface waves (SWs) that share the same radiating aperture. The outward SW is launched from the center of the aperture, while the inward SW is excited from the edge, through a two-layer feeding structure featuring a circular corner reflector at the aperture boundary. These SWs produce two circularly polarized broadside beams with opposite circular polarizations after interacting with the modulated impedance boundary condition (IBC) imposed by the MTS. By properly defining the impedance modulation, similar performances are achieved for the two polarizations in terms of beamwidth and efficiency. A practical feeding structure has been designed that employs a concentric triaxial cable, with a transition to coplanar waveguide for one of the two polarizations. This solution represents a promising approach for achieving dual-polarization in MTS antennas, offering high-performance with a simple and low-profile structure.