Dual Offset Reflector Antenna Systems with Rotationally Symmetric Aperture Distributions.

Abstract : A detailed derivation is given of the basic design equation for a dual offset reflector antenna consisting of a paraboloid main reflector and a confocal/hyperboloid or ellipsoid subreflector. The basic design equation is a relation between the subreflector eccentricity; the relative orientations of the axes of the main reflector, subreflector, and feed; and the paraboloid focal length. If satisfied, the basic design equation guarantees that that (to within the geometric optics approximation) a circularly symmetric and linearly polarized feed pattern will give rise to a circularly symmetric and linearly polarized main aperture distribution and far field pattern. The relation between the amplitude distribution of the feed pattern and main aperture is also derived.