Multiple beam antenna concepts for satellite communications

Multiple beam antennas (MBA) for satellite communications usually provide a contiguous coverage over a specified field-of-view by using high gain overlapping spot beams. The common design objective for all MBAs is to maximize the minimum gain within the coverage region. If the MBA has uniform beams arranged in a hexagonal grid, the minimum gain occurs at the triple beam cross-over and the gain variation within the coverage region is typically around 4 dB. The trades for gain optimization are often coupled with consideration such as (a) low sidelobe levels for frequency reuse or for minimizing interference effects (b) minimizing the number of beams to reduce the antenna complexity (c) power and traffic allocation flexibility and (d) size and mass constraints. Antenna designs and beamforming network (BFN) concepts suitable for MBAs are discussed in this paper including design examples.