Cross polarization in beam waveguide-fed Cassegrain reflector antennas

The sensitivity of the cross-polarization level to a deviation from the geometrical condition derived by M. Mizusawa and T. Kitsuregawa (1973) for different geometrical configurations is studied. This condition restricts the number of possible beam waveguide configurations for beam waveguide-fed Cassegrain reflector (BFCR) antennas. For a symmetrical feed, this condition results in a symmetrical aperture distribution with no cross-polarized component. By examining a number of beam waveguide configurations satisfying the condition, it was observed that for a linearly polarized feed, the cross-polarization level is very sensitive to a deviation from this condition. For a circularly polarized feed, deviation from this condition does not increase the cross-polarization level; however, it results in the squinting of the beam for BFCRs