Numerical study of radiation from hard waveguide with lossy wall region-first approach to square hard horn

Radiation from a circularly polarized hard cylindrical waveguide is considered. The losses of the dielectric lining as well as radiation from the walls are included in the analysis. It is shown that for small horn sizes (D approximately lambda /sub 0/) and standard dielectric material the hard horn has no advantages over the empty horn. For greater sizes (D approximately 4 lambda /sub 0/) the hard horn shows better cross polarization and higher efficiency than an empty horn, but the bandwidth is limited. Dielectric losses increase the minimum level of the cross polarization for large D/ lambda /sub 0/ and introduce significant attenuation which is undesirable in low-noise applications. The square hard horn with high permittivity walls has parameters similar to the circular hard horn.<>