System applications of beam forming networks

Various types of beam forming networks are discussed including those at radio frequency (the Butler matrix and the Maxson-Blass array) and those at intermediate frequency. The application of beam forming networks to three-dimensional radar surveillance systems is outlined, noting adaptive receiver switching, range-dependent coverage, interference reduction, clutter isolation, and tracking. Other applications are described such as in conjunction with track-while-scan radars, in the azimuth plane, and as part of bistatic systems.