An intermodulation suppression technique for transmit active phased array satellite antennas with multiple shaped beams

A technique to improve the efficiency of multibeam transmit active phased array satellite antennas with shaped beams is proposed. The approach is based on selecting fundamentally different or orthogonal aperture phase distributions per beam, resulting in intermodulation beams that are different from the carrier beams for the same coverage. This allows for optimization for maximum effective isotropic radiated power and minimum intermodulation power over the coverage area with respect to the aperture phase excitation. Lower radiated intermodulation power means that the amplifiers can be operated more nonlinearly, resulting in higher antenna efficiency. Simulations for an extended Continental U.S. region suggest that the antenna dc power can be reduced by about 50% for four single carrier beams. The technique applies to any beam coverage regions, either identical or different.