Crosspolarisation in beam-waveguide feeds

The theory of the propagation of Gaussian beams has recently been developed to take account of the higher-order cross-polarised modes generated by offset curved reflectors, as used in beam waveguides. A comparison between results obtained by this analytical approach and by numerical computation of the diffraction integrals shows excellent agreement, confirming the relevance of the idealised theory to beam waveguides of finite dimensions with practical feedhorns.