A novel horn radiator with high aperture efficiency and low cross-polarization and applications in arrays and multibeam reflector antennas

A step horn structure is presented that yields about 90% aperture efficiency with low cross-polar radiation. It is found that for obtaining high aperture efficiency, the horn aperture should consist of only the TE_z type of modes in appropriate amplitudes and phases. The desired TE_z modes are produced using multiple steps in the horn walls. The distances between the steps are critical to suppress the undesired TM_z modes. Radiation characteristics of high efficiency circular and square horns are presented and potential applications of such high efficiency horns are discussed.