Low Cross-Polar Radiation from Wide Flare-Angle Conical Corrugated Horns

The prediction of the radiation pattern of conical corrugated horns is described using the spherical-mode expansion method. In particular, cross-polar patterns are obtained for several horns and excellent agreement with measured patterns is demonstrated. Three mechanisms of mode conversion are identified and one in particular investigated in detail. It is shown that mode conversion along the horn is not a significant effect and that the peak cross-polar radiation from a 30° corrugated horn lies below - 45 dB over more than a 10% bandwidth.