Analysis of rim loaded Cassegrain antennas

A complete analysis of radiation pattern of centered symmetric Cassegrainian antennas is carried out. The peripheral rims of both the reflector and subreflector are assumed to be loaded by material media described in terms of surface impedances. The geometrical theory of diffraction (GTD), properly generalized to handle surface impedance boundary conditions, is used to compute the far-out sidelobes caused by various diffraction processes, while the physical optics (PO) approach is used in the main beam region. Some examples are also referred to; the patterns of co-polar and cross-polar components are exploited.