Plural hybrid mode multiflare conical horn with reduced cross polarisation and sidelobe levels

Abstract

A new horn antenna exhibiting low cross polarisation and sidelobe levels over a wide frequency band is investigated both analytically and experimentally. The antenna consists of a dielectric loaded multiflare conical metal horn that can support the balanced hybrid modes. The higher order modes excited with appropriate relative amplitude and phase by the dominant HE11 mode incident on a symmetric discontinuity in an oversized cone of a multiflare horn are utilised to effect sidelobe reduction with low cross polarisation. The technique of dielectric loading is combined with multimode operation to contribute to increased directivity and on axis gain. Analytical results show good overall agreement with experimental measurements in the 10–16 GHz frequency band. This new type of multimode horn is potentially simple to design, analyse and manufacture yet exhibits many of the desirable features of the corrugated horn. Hence, the proposed multimode dielectric loaded multiflare conical horn, with its improved performance of better directivity and on axis gain at low cross polarisation and sidelobe levels, represents an attractive alternative to the corrugated horn antenna for satellite communications.