Page 332 - Radar Technology Encyclopedia

radar, aerostat radar, airborne-early-warning (AEW) 322

tude or surface targets. Power for the radar can be supplied, craft tail-protection radar; doppler radar; synthetic aper-
and data returned to the surface station, through the tethering ture radar.) PCH
cable. The operational difficulties of maintaining the aerostat Ref.: Povejsil (1961); Stimson (1983); Morris (1988); Morchin (1990); Neri
in position under harsh weather conditions have precluded (1991), p. 175; Long (1992).
most military exploitations of aerostat radars, but some suc- An airborne early warning (AEW) radar is carried by an
cess has been achieved in application to border surveillance, airborne or spaceborne platform whose function is the detec-
as for drug enforcement and immigration control. Figure R1 tion of airborne intruders into the air space under surveil-
shows an radar surveillance aerostat designed for battlefield lance. For aircraft-based AEW radar, the primary targets are
surveillance. DKB usually aircraft and cruise missiles, but the mission of modern
Ref.: Skolnik (1988), pp. 262–263; Long (1992), Ch. 11. AEW can extend to the detection and track of several addi-
tional types of targets, including ships, land- and sea-
launched ballistic missiles, and various kinds of land-based
targets.
AEW radar characteristics vary depending on mission
requirements and the characteristics and limitations of the
host platform. Two U.S. systems stand out as prime examples
of military AEW radar applications. The first, the E-3A Air-
borne Early Warning and Control System (AWACS), shown
in Fig. R2, is a Boeing 707-320 jet aircraft modified to carry
the Westinghouse-developed, S-band, pulsed doppler AN/
APY-1 radar and other command and control equipment and
crew. The AWACS radar has several operational modes,
including long range air search, maritime search, and detec-
tion of moving targets over land and sea clutter. The AWACS
radar has recently been adapted, for Japan, to the more mod-
ern Boeing 767 aircraft.
Figure R1 Small aerostat surveillance system, designed by
Westinghouse for battle field surveillance, using a modified
AN/APG-66 AI radar.

Airborne radar is any radar installed aboard a platform
designed to operate within the earth’s sensible atmosphere.
Thus an active radar missile seeker is technically an airborne
radar, as is an aerostat radar or one installed in a remotely
piloted vehicle (RPV). However, most airborne radars are
found in manned aircraft. Commercial airliners, transport air-
craft, and many private aircraft are equipped with airborne
weather radar, to allow the pilot to detect and avoid severe
weather cells or storms. The air forces of many nations
employ airborne early warning (AEW) radar at UHF to S-
band frequencies for surveillance of their national air, land,
and sea boundaries, and air defense fighter aircraft are
equipped with airborne intercept (AI) X-band radars for fire Figure R2 The Boeing E3A AWACS (from Morchin, 1990,
Fig. 1.2, p. 11).
control and missile guidance. Other types of military airborne
radar include terrain-following radar to permit all-weather, The E-2C Hawkeye, shown in Fig. R3, was developed by
low-altitude penetration of enemy airspace, and tail-warning Grumman Aerospace for the U.S. Navy, specifically for car-
radar to alert a bomber aircraft of rear attack. Both military rier-based operations. Designed to serve as “the eyes of the
and civilian organizations utilize synthetic aperture radar fleet,” the UHF, LPRF radar, developed by General Electric,
(SAR) techniques at various operating frequencies for high- has undergone several evolutions since its introduction in
resolution air-to-surface mapping. 1960.
Because of the nature of the platform, size and weight are Major improvements have been made in the radar’s mov-
critical issues in airborne radar, and the radar’s power-aper- ing-target detection, multiple-target tracking, and electronic
ture product is limited also by vehicle configuration and by counter-countermeasure (ECCM) capabilities.
the primary power supply, which is usually supplied by the Both the AWACS and the Hawkeye AEW systems were
aircraft propulsion system (engines). (See also airborne designed to operate as airborne command, control, and com-
3
early warning radar; airborne intercept radar; airborne munications (C ) centers, with capability to direct multiple
mapping radar; airborne weather avoidance radar; air- interceptor aircraft engagements of hostile airborne intruders.