Fixed beam and mechanically steerable antennas

The principal design features and performance characteristics of fixed-beam and mechanically scanned antennas that are commonly found in today's operational electronic countermeasures (ECM) and electronic support measures (ESM) equipment are reviewed. The requirements driving the design of steerable ECM antennas are wide bandwidth, high efficiency, and the ability to handle high average power levels. The main types of antennas include spirals, helices, horns, and waveguide radiators. ESM antennas are characterized by wide bandwidth and multiple polarization responses to insure reception of all signals of interest. The types of ESM antennas discussed here include log periodic dipole arrays, spiral antennas, and wideband horns.