Special purpose arrays for radar application

Three kinds of special-purpose arrays are discussed: broadband and dual-band arrays, conformal arrays, and arrays for limited sector scanning. Emphasis is placed on several important classes of limited scan antennas such as a single reflector with phased array, a system consisting of a main reflector or lens with a subreflector or lens and a phased array, and an aperiodic structure requiring the use of lossy transmission line connections and a fairly complex beam steering. The present radar phased-array technology is focused on arrays conformal to aircraft and spacecraft with hemispherical scan capability or extremely wide bandwidth or several operating bands, and arrays for scanning high-gain beams over very limited sectors.