Irregular segmentation of paraboloidal reflectors

The use of flat sections to approximate a paraboloidal reflector have been developed for satellite antennas to facilitate their deployment in space. To that end, reflectors using both hexagonal and triangular segmentation have been developed. Segmented reflectors could be useful for low cost, light weight, and easily erected satellite Earth terminal or TVRO antennas. To make such antennas cost effective, one would like to minimize the number of flat sections required to obtain a satisfactory radiation pattern envelope (RPE) as prescribed by the CCIR standard. Analyses by Anderson and Wu (1984) for triangular, by Brown (see IEEE AP-S Intl. Sym., Newport Beach, CA, p.1186-9, 1995) for hexagonal, and by Brown and Kahn for square segmentations show significant grating lobe problems, even for small flat sections (/spl lambda//16 vertex error or less). This occurs because there is a periodic segmentation pattern (when projected on an aperture plane perpendicular to the axis of the paraboloid) that extends across the entire face of the reflector. A number of methods for breaking up this periodicity are presented.