Trade studies to provide two independent simultaneous transmit down-link beams for geostationary orbit MILSATCOM applications will be completed. Two direct radiating active array solutions will be analyzed. Both use a 32" x 32" array aperture as required for 1 degree half power beamwidth with approximately 450 elements arranged in a triangular array element lattice to minimize the number of components needed. Both utilize a novel method for obtaining maximum EIRP, acceptable SSPA noise power ratio and power added efficiency. One solution utilizes a beamformer comprised of 2D Rotman lens stack for frequency independent simultaneous beam formation. The approximately 300 lens beam ports are selected by a 2 x 300 beam RF switch. A second solution utilizes a beamformer comprised of a 2 x 450 corporate fed active phased array. Each active element will have two independent phase shifters to enable the simultaneous independent beam formation. Two array fed reflector configurations will be also analyzed. Corporate feed array with two phase shifters/variable attenuators per element and confocal lens stack fed configurations will be considered. Two non-array fed reflector configurations will be analyzed. Analysis trades for performance, cost, weight, power, isolation, and coupling will be performed. Spatial intermodulation effects will be calculated.
Keywords: Milsatcom, Advanced Ehf, Multibeam, Phased-Array, Tca, Tsat, Rotman Lens, Sensors
