Multi-Beam Phased-Array Antenna Beamformers

A Novel Multibeam Phased Array Beamformer technology development is described suitable for Transformational Communications applications. The beamformer will be designed for Advanced EHF satellite downlink and uplink payloads and create many simultaneous high gain pencil beams feeding a planar array of 2,000 or more elements from geostationary earth orbit. The beamformer uses row and column two dimensional Rotman lens stacks feeding sub arrays of contiguous more closely spaced elements. Radiating sub array elements each have phase shifters for beam fine steering and shaping within the equilateral triangular beam lattice of the Rotman lens stacks capable of covering the entire 17.4º earth disc. The sub arrays are arranged in a triangular (hexagonal) element lattice to minimize the number of elements and hence passive and active components needed. The Rotman lens stacks themselves feed the sub arrays directly through each of their array ports. At each beam port of the Rotman lens stack, a narrow pencil beam is formed that has frequency independent beam pointing angle due to the true time delay nature of the Rotman lens phase excitation creation. Within each of these beams, the sub array phase shifters provide fine steering.