Technical memorandum: Bandwidth of a square hard horn

Abstract

Horn antennas with dielectrically-filled longitudinal corrugations have recently been presented, and have been referred to as hard horns. Cylindrical hard horns can support a TEM wave at the design frequency, providing uniform aperture distribution and zero cross polarisation: this makes them attractive to use as compact elements in cluster feeds. In the paper the characteristic equation of a square hard waveguide is presented, and the crosspolar bandwidth is determined.