Very broadband feed for paraboloidal reflectors

A compact, very broadband, linearly polarized feed unit has been developed for use in large aperture paraboloidal reflectors. The unit, a multi-dipole array provides 4 separate feeds covering 4 adjacent 2:1 bands with good front to back ratio and VSWR. On three of the bands front to back ratio is generally 10 db and of ten 15 db or better. Front to back ratio on the lowest band is better than 8 db. Model tests of the feed plus reflector indicate that secondary pattern beamwidths and side lobes are good over the band with side lobes between 20 to 30 db down in the E plane and below 10 db in the H plane. Directivity as calculated from beamwidths closely corresponds to theoretical directivity over the whole band. Compact mechanical packaging is achieved in balun construction.