Modifications of horn antennas for low sidelobe levels

Abstract

A modified horn antenna with significantly reduced backlobes over nearly a two-to-one frequency band is discussed. This horn has a well-defined phase center at its apex, and the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> - and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</tex> -plane patterns are nearly identical over the frequency band if the horn has a square (or circular) aperture. Horns considered cover a wide range of flare angles and include one which fits the criterion for the optimum horn at the lower end of the operating frequency band. The VSWR is less than 1.2 over most of the frequency band.