On the aperture illumination of multibeam satellite antennas

The dimensioning of reflectors with optimal aperture illumination is considered. For circular aperture illuminations of the form A + B 1-(p/a)2 v (a: radius of the aperture, p: radial coordinate) diagrams are presented which show sidelobe level, illumination efficiency, half power beamwidth, and gain in terms of the parameters A and v. Aperture diameter and contour gain are evaluated for an optimally illuminated circular coverage region. The contradicting requirements for low sidelobe level and narrow spacing of adjacent beams are discussed. Considering a formulation for the aperture field, simple relations for the radiation field of reflector antennas can be stated. For a given radiation field it is possible to quickly determine an appropriate aperture spreading and the requisite aperture diameter.