Analysis of a hard corrugated conical horn by using the method of generalised scattering matrices

A conical horn with a hard wall section realised by longitudinal grooves filled with dielectric is analysed. The analysis is based on stepwise representation of the conical surfaces and on the use of the method of generalised scattering matrices. The eigenmodes for the corrugated sections are determined by the asymptotic boundary condition. It is shown that the horn can provide high aperture efficiency (above 85%) and low cross-polarisation level (below -30 dB) in some frequency band, but the horn performance strongly depends on the hard section configuration because of wave reflections between the throat and aperture