Adaptive array antenna beamforming architectures as viewed by a microwave circuit designer

Five alternative architectures are introduced for adaptive beamforming in array antennas. The beamforming process is carried out in the baseband, local, radio, spatial, and optical stage, respectively, for the five architectures. Their pros and cons are discussed from the viewpoint of microwave circuit design. As practical hardware implementations of these architectures, some state-of-the-art examples of recently developed microwave signal processor devices and antennas are also shown