A Complete GTD Analysis of RIM Loaded Cassegrain Antennas

A complete numerical analysis of the radiation pattern of centered symmretric Casse grain antennas is carried out. The peripherical rims of both the reflector and the 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; the patterns of copolar and crosspolar components are exploited.