APQ-181 radar
Encyclopedia
The AN/APQ-181 is an all-weather, low probability of intercept
(LPI) radar
system designed by Hughes Aircraft
(now Raytheon
) for the U.S. Air Force B-2A Spirit bomber aircraft. The system was developed in the mid-1980s and entered service in 1993. The APQ-181 provides a number of precision targeting modes, and also supports terrain following and terrain avoidance. The radar operates in the Ku band
(a subset of the J band
). The original design uses a TWT-based transmitter
with a 2-dimensional passive electronically scanned array
(PESA) antenna
.
In 1991, the B-2 Industrial Team (including Hughes as a major subcontractor) was awarded the Collier Trophy
in recognition of the "design, development, production, and flight testing of the B-2 aircraft, which has contributed significantly to America's enduring leadership in aerospace and the country's future national security."
In 2002, Raytheon was awarded a contract to develop a new, Active Electronically Scanned Array
(AESA) version of the APQ-181. This upgrade will improve system reliability, and will also eliminate potential conflicts in frequency usage between the B-2 and commercial satellite systems that also use the J band.
In 2008 the Federal Communications Commission
accidentally sold the APQ-181 frequency to a commercial user resulting in the need for installing new radar arrays at a cost of over $1 billion. All B-2 aircraft are expected to have the upgraded radar by 2010.http://www.military.com/features/0,15240,187202,00.html
Low probability of intercept
A low-probability-of-intercept radar is designed to be difficult to detect by passive radar detection equipment while it is searching for a target or engaged in target tracking...
(LPI) radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
system designed by Hughes Aircraft
Hughes Aircraft
Hughes Aircraft Company was a major American aerospace and defense contractor founded in 1932 by Howard Hughes in Culver City, California as a division of Hughes Tool Company...
(now Raytheon
Raytheon
Raytheon Company is a major American defense contractor and industrial corporation with core manufacturing concentrations in weapons and military and commercial electronics. It was previously involved in corporate and special-mission aircraft until early 2007...
) for the U.S. Air Force B-2A Spirit bomber aircraft. The system was developed in the mid-1980s and entered service in 1993. The APQ-181 provides a number of precision targeting modes, and also supports terrain following and terrain avoidance. The radar operates in the Ku band
Ku band
The Kμ band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to —in other words, the band directly below the K-band...
(a subset of the J band
J band
J band can refer to two different regions of the electromagnetic spectrum, in the radio and near-infrared.-Radio:The J band is the range of radio frequencies from 10 GHz to 20 GHz in the electromagnetic spectrum. This is equal to wave lengths between...
). The original design uses a TWT-based transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
with a 2-dimensional passive electronically scanned array
Passive electronically scanned array
A passive electronically scanned array , contrary to its active counterpart AESA, is a phased array which has a central radiofrequency source , sending energy into phase shift modules, which then send energy into the various emitting elements in the front of the antenna...
(PESA) antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
.
In 1991, the B-2 Industrial Team (including Hughes as a major subcontractor) was awarded the Collier Trophy
Collier Trophy
The Collier Trophy is an annual aviation award administered by the U.S. National Aeronautics Association , presented to those who have made "the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space...
in recognition of the "design, development, production, and flight testing of the B-2 aircraft, which has contributed significantly to America's enduring leadership in aerospace and the country's future national security."
In 2002, Raytheon was awarded a contract to develop a new, Active Electronically Scanned Array
Active Electronically Scanned Array
An Active Electronically Scanned Array , also known as active phased array radar is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules . AESAs aim their "beam" by broadcasting radio energy that interfere...
(AESA) version of the APQ-181. This upgrade will improve system reliability, and will also eliminate potential conflicts in frequency usage between the B-2 and commercial satellite systems that also use the J band.
In 2008 the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
accidentally sold the APQ-181 frequency to a commercial user resulting in the need for installing new radar arrays at a cost of over $1 billion. All B-2 aircraft are expected to have the upgraded radar by 2010.http://www.military.com/features/0,15240,187202,00.html
See also
- List of radars
- Joint Electronics Type Designation SystemJoint Electronics Type Designation SystemThe Joint Electronics Type Designation System , which was previously known as the Joint Army-Navy Nomenclature System and the Joint Communications-Electronics Nomenclature System, is a method developed by the U.S. War Department during World War II for assigning an unclassified designator to...
(JETDS)