Distributed Beam Former for Distributed-Aperture Electronically Steered Antennas

Abstract : Applications for electronically steered arrays (ESA) in army communication systems span frequencies from UHF to Ka bands and requirements that include single and multiple beams, various scanning speeds, and different polarizations. The radiating apertures can be planar, conformal or segmented and distributed over multi-faceted structures. Examples include distributed apertures on military vehicles, antennas on elevated posts or towers on stationary or mobile platforms, and others. The beam former is an essential part of the ESA design and its optimization in functionality and cost lead to improving the whole system. This paper presents a concept for a distributed beam former that is composed of two stages: an RF stage with limited scanning steps and a digital stage that is capable of steering multiple beams in all required directions. The two-stage beam former uses fewer A/D converters than its all-digital counterpart and lower losses than the all-RF beam former. Examples are given for multi-faceted apertures.