Multi-Beam Dual Polarised Metasurface Antenna in Ka-band

This paper aims to propose a novel design strategy for a Multi-Beam dual-polarized Metasurface (MTS)-based aperture, utilizing the concept of inward and outward surface wave (SW) duplexing. Two different solutions are implemented to design the MTS providing dual polarized beams in desired directions. The first solution divides the aperture into a number of sectors, each responsible for the generation of one beam, while the second solution overlaps multiple modulations over the aperture. In both the cases, a vertical dipole positioned at the center of the aperture can launch an outward radial SW; this wave interacts with the modulated MTS and generates multiple simultaneous beams with either right-hand or left-hand circular polarization, depending on the modulation. Additionally, using edge excitation, an inward travelling SW is generated, which propagates radially towards the vertical dipole at the center, generating multiple beams at the same pointing angles, but with opposite polarization. The antenna design includes an innovative triaxial feeding system, able to excite both the inward and the outward travelling SW. This simple solution has the advantage of maintaining a low profile without compromising power handling or over-complicating the feeding structure.