Adaptive arrays for communications

The basic principles of adaptive arrays are outlined, emphasizing the requirements of such arrays for communications, as distinct from radar. These arrays are designed so that they automatically adapt their responses to give low gain to unwanted signals, while maintaining adequate gain to a wanted signal. The basic approaches to achieving this aim are described, with some comment on the relative merits of different systems in terms of cost, complexity and performance. Some practical aspects affecting design and performance are discussed and references are made to actual systems.