Enhancing the Radiation Performance of a Pyramidal Horn Antenna by Loading a Subwavelength Metasurface.

We present the detailed design and experimental demonstration of a low-sidelobe horn antenna based on controlling the amplitude and the phase distribution of the electromagnetic fields over the aperture of the horn antenna using a thin single-layer metasurface lens. The lens is composed of two identical subwavelength metallic square-ring arrays printed on the two sides of a single dielectric layer. By placing the metasurface lens inside a standard pyramidal horn, the electromagnetic fields over the horn aperture can be manipulated, resulting in low sidelobe radiation in both E- and H-planes. Both simulated and measured results demonstrate the tapered field distribution over the horn aperture and the significant reduction of sidelobes in the E-plane as well as the reduction of the backlobes.