Additive manufactured metal-only modulated metasurface antennas

In metasurface (MTS) antennas, a surface wave (SW) is gradually transformed into a leaky wave, owing to the SW interaction with a reactance tensor periodically modulated in the aperture plane. In such antennas, the modulated reactance is typically obtained by subwavelength patches printed on a dielectric substrate. As an alternative technology, we propose the use of a class of metal-only MTSs in the synthesis of the reactance tensor. The absence of dielectric is useful to withstand harsh environments in space applications. The proposed element consists of a metallic cylinder with elliptical cross section, placed on a ground plane and arranged in a square lattice with subwavelength unit cells. This structure is well suited for fabrication by metal additive manufacturing. We have applied the metal cylinders in the design of a right-handed circularly polarized antenna, with broadside pencil beam at Ka-band. The obtained performance has been verified by full-wave simulations. A prototype has been successfully manufactured and measured, showing a good performance.