Cross Polarization and Beam Squint in Single and Dual Offset Reflector Antennas

Cross polarization (XPOL) and beam squint phenomena of reflector antennas are examined in detail. Emphasis is on the explanation of the absence of XPOL and the presence of beam squint in offset parabolic reflectors illuminated by a circularly polarized feed. Linearly polarized feeds are also considered for both the offset and axisymmetric configurations. Although many of these results are known, they are presented in a single coherent treatment. In addition, the results for polarization and beam squint characteristics of prime-focus offset parabolic reflector antennas are extended to dual offset configurations based on computed data using the physical optics code, GRASP7 (TICRA, 1988).