Investigations on directivity improvement of wide flare angle conical horns using inserted metallic discs

A simple and low cost method to enhance gain of wide angle conical horns is described. The method consists of inserting disc(s) inside the horn at particular axial locations. Investigations realised by simulation and measurements are reported for different flare angle horns as a function of different geometrical parameters and frequency. The study shows that aperture efficiency enhancement can be achieved for large flare angle horns using this concept, thus resulting in an increase of the directivity. The insertion of discs influences the impedance match. However, since the objective is to study the directivity enhancement, the mismatch losses are removed from experimental data. In practice, the horn design can incorporate a matching network to eliminate the problem