Scan performance of dual offset reflector antennas for satellite communications

This paper summarizes the basic numerical steps employed to analyze dual offset reflector antennas. The technique is based on the application of the geometrical theory of diffraction from the subreflector and physical optics (PO) scattering from the main reflector. The PO integral is evaluated by using the Jacobi-Bessel series expansion. Numerical results are presented for the off-axis (scan) performance of an offset (clear aperture) Cassegrain antenna and comparison is made between a Cassegrain antenna and its equivalent paraboloid.