Broadband compact horn feed for prime-focus reflectors

A compact flare angle controlled corrugated horn antenna with a 60° half beamwidth is optimised by using a moment method for bodies of revolution. The horn has corrugations with simple rectangular cross-sections and is excited by a smooth wall circular waveguide. The resulting 15 dB beamwidth varies by <18% and the crosspolar sidelobe levels are more than 26 dB below the mainlobe, both over a 1.8:1 bandwidth. All results are confirmed by measurements. The horn is suited for broadband feeding of e.g. prime-focus reflectors in radio astronomy applications.