Design of a Low-Sidelobe Pyramidal Horn Antenna based on the Image Theory

A new approach is presented to design low-sidelobe pyramidal horn antennas. The image theory is applied to seek the tapered electric field distribution on the aperture of normal pyramidal horns so that low-side levels can be found in both E and H planes. A metasurface with periodic subwavelength elements is developed to achieve zero reflection phase at the operating frequency. When placing two such metasurfaces on the two wide walls of the pyramidal horn, low sidelobes are expected. Simulations are conducted to validate the prediction.