Multibeam Antennas

Abstract

The article introduces multibeam antennas by reviewing a number of applications describing their importance for modern radar and communications systems. Simple aperture distributions and antenna sizing formulas for beamwidth and gain rolloff are discussed, and examples are provided on the implementation of both active and passive multibeam antennas using different beamforming technologies. The problem of forming simultaneous multiple beams from a common aperture is investigated considering the Stein limits for passive antennas. The implementation of optimum beamforming networks is discussed. Both array antennas and array‐fed reflector antennas, including dual‐ and multimode antenna systems, are reviewed. The design of multibeam reflector antenna systems is considered in detail. Scan aberrations and cross‐polarization effects of the signal‐offset reflector are quantified, describing means to improve the antenna performance. The potential of compensated dual‐offset reflectors, including front‐fed and side‐fed offset Cassegrain antennas for large scan angles, is demonstrated.