Optimum low sidelobe high crossover multiple beam antennas

Simultaneous multiple beam antennas (MBA´s) with low sidelobe high crossover beams are considered. A simplified proof is presented which shows dissipative loss of typically -3 dB must be accepted. The optimum efficiency for the constrained fed MBA is shown to be achieved by placing attenuation in the aperture of a Butler matrix (BM) in accordance with the desired tapered aperture distribution. A combination of aperture attenuation and feed design, including the use of overlapping orthogonal feed distributions, is considered for lens type MBA´s. The optimum efficiency is shown to be achieved with relatively simple feeds for a broad class of desired beam shapes.