Analysis, design and measurements on an active focal array fed reflector

ALCATEL develops reflector antennas with multifeed arrays for civil and military communications satellites. In this paper, an X band, high gain spot beam antenna with accurate beam steering and shaping, and low sidelobe levels is presented. The selected antenna is comprised of an offset parabolic reflector with overlapping feed cluster. Pattern synthesis is performed with an active beamforming network (BFN). Design rules are gained from a detailed analysis of the antenna architecture. A demonstrator is designed and measured. Low sidelobes (-25 dB), accurate steering (0.05°), and good agreement between theoretical and experimental spots are demonstrated. Attention is paid to optimizing the design of constitutive elements (lightweight planar focal array, shaped reflector)