RADAR SYSTEMS CLASSIFICATION METHODS
During World War II, each service used its own method to designate its electronic radar/tracking systems. For example, Army radars were classified under the initials SCR, which stood for "Signal Corps Radio." Different designations for similar systems confused manufacturers and complicated electronics procurement. In February 1943, a universal classification system was implemented for all services to follow, ending the confusion. To indicate that an electronic system designation followed the new universal classification, the letters "AN," for Army-Navy, were placed ahead of a three-letter code. The first letter of the three-letter code denoted the type of platform hosting the electronic device, for example: A=Aircraft; C=Air transportable (letter no longer used starting in the1950s); F=Fixed permanent land-based; G=General ground use; M=Ground mobile; S=Ship-mounted; T=Ground transportable. The second letter indicated the type of device, for example: P=Radar (pulsed); Q=Sonar; R--Radio. The third letter indicated the function of the radar system device, for example: G=Fire control; R=Receiving (passive detection); S=Search; T=Transmitting. Thus an AN/FPS-20 represented the twentieth design of an Army-Navy "Fixed, Radar, Search" electronic device.
World War II Radars
This section describes the World War II vintage radars that saw service during the Cold War. The systems are listed in numerical order, bypassing the three-letter code. During World War II, search and height-finder radars became components of America's electronic arsenal. The function of the search radar was to detect and obtain a line of bearing on an aircraft. Early models such as the SCR-270 and 271 looked like large bed-springs. Later designs, such as the AN/CPS-5 looked like a large oval dish. Search radars generally rotated full circle around a central axis. In contrast to the rotating search radar antenna, the horizontally mounted height-finder radar focused on the tracked aircraft's reported bearing. The radar antenna dish then scanned up and down to provide the operators with the estimated height of the aircraft.
AN/TPS-lB, 1C, 1D
Bell Telephone Laboratories developed this radar that subsequently was produced by the Western Electric Company. A crew of two could operate the radar. The 1B model could detect bombers at 10,000 feet at a distance of 120 nautical miles. The height detection and range on the 1C and 1D models exceeded those of the 1B. The transmitter sent its pulse at an L-band frequency between 1220 to 1280 megahertz (MHz). This long-range search radar was used in the temporary Lashup system beginning in 1948.
Developed by MIT's Radiation Laboratory, this height-finding radar was nicknamed "Beaver Tail." The radar was designed to be used in conjunction with the SCR-270 and SCR-271 search sets. The CPS-4 required six operators. This S-band radar, operating in the 2700 to 2900 MHz range, could detect targets at a distance of ninety miles. The vertical antenna was twenty feet high and five feet wide. This radar was often paired with the AN/FPS-3 search radar during the early 1950s at permanent network radar sites.
Bell Telephone Laboratories and General Electric developed this search radar. General Electric began producing sets in January 1945. Designated as a transportable medium-range search radar, the unit was ideal for use in the Lashup system in conjunction with the AN/TPS- 10 height-finder radar. It could be operated with a crew of ten. Some of these units remained to serve in the first permanent network. Designed to provide a solid search of up to 60 miles at 40,000 feet, the radar often had success tracking aircraft as far as 210 miles away.
AN/CPS-6, 6A, 6B
The AN/CPS-6 was developed during the later stages of World War II by the Radiation Laboratory at MIT. The first units were produced in mid-1945. General Electric developed and produced the A-model and subsequent B-model at a plant in Syracuse, New York. The unit consisted of two antennas. One of the antennas slanted at a forty-five degree angle to provide the height-finder capability. Initially, the radar was designed to detect fighter aircraft at 100 miles and16,000 feet. The radar used five transmitters that operated at S-band frequencies ranging from 2700 AN/CPS-6to 3019 MHz. It took twenty-five people to operate the radar. An AN/CPS-6 radar was installed as part of the Lashup system at Twin Lights, New Jersey, in 1949 and proved capable of detecting targets at ranges of eighty-four miles. The first units of the follow-on 6B radar set were ready for installation by mid-1950. Fourteen 6B units were used within the first permanent net-work. A component designed to improve the radar's range was added in 1954. Initial tests showed the 6B unit had a range of 165 miles with an altitude limit of 45,000 feet. One radar unit and its ancillary electronic equipment had to be transported in eighty-five freight cars. The Air Force phased out the 6B model between mid-1957 and mid-1959.
AN/TPS-10, 1OA /AN/FPS-4
MIT's Radiation Laboratory developed and produced the first version of this radar near the end of World War II. Zenith produced the A-model sets in the post-war period. The vertically mounted antenna was three feet wide and ten feet long. Two operators were needed to run the set. The initial model operated at a frequency of 9000 to 9160MHz and had a maximum reliable range for bombers of 60 miles at 10,000 feet. An updated version designated the AN/FPS-4 was produced by the Radio Corporation of America (RCA) beginning in 1948. Some 450 copies of this and the trailer-mountedAN/MPS-8 version were built between 1948 and 1955.
Early Cold War Search Radars
Early Cold War search radars essentially were advanced or improved versions of World War Il era sets. In some cases, the performance of the new sets fell short of expectations.
The AN/FPS-3 was a modified version of the AN/CPS-5 long-range search radar. The first units came off the Bendix production line and were ready for installation in late 1950. Forty-eight of these L-band units were used within the first permanent network. The AN/FPS-3B incorporated an AN/GPA-27, which increased the search altitude to65,000 feet. Installation of these modifications began in 1957.
The AN/FPS-5 was a long-range search radar produced in the early 1950s by Hazel-tine. Deployment was limited.
The AN/FPS-8 was a medium-range search radar operating on the L-band at a frequency of 1280 to 1380 MHz. Developed in the 1950s by General Electric, over 200 units of this radar were produced between 1954 and 1958. Variants of this radar included theAN/GPS-3 and the AN/MPS-11.
This unit was essentially a stripped down version of the AN/CPS-6B. Thirteen of these units served within the first permanent network.
SAGE System Compatible Search Radars
Various manufacturers began design work on compatible search radars for SAGE systems in the mid-1950s in conjunction with the development of the SAGE Command and Control System. Because Project LAMPLIGHT indicated radar vulnerability to electronic countermeasures, the Air Force developed a series of radars that could shift frequency. These frequency-diversity (FD) radars included the AN/FPS-24, AN/FPS-27, andAN/FPS-35.
AN/FPS-7, 7A, 7B, 7CI 7D
In the mid-1950s, General Electric developed a radar with a search altitude of 100,000 feet and a range of 270 miles. This radar was significant in that it was the first stacked-beam radar to enter into production in the United States. Designed to operate in the L-band at 1250 to 1350 MHz, the radar deployed in late 1959 and the early 1960s. The AN/FPS-7 was used for both air defense and air traffic control in New York, Kansas City, Houston, Spokane, San Antonio, and elsewhere. In the early 1960s, a modification called AN/ECP-91 was installed to improve its electronic countermeasure (ECM) capability. About thirty units were produced.
This Bendix-built radar was an AN/FPS-3 search radar with an AN/GPA-27 installed. Designed to operate in the L-band frequencies of 1250 to 1350 MHz, the radar had a range of over 200 miles. By the late 1950s this radar dominated the United States radar defense net. Deployment continued into the early 1960s. In June 1959, Bendix received a contract to provide private industry's MK-447 (the same as the military's AN/GPA-103) and MK-448 (AN/GPA-102) anti-jam packages to the radars. With the addition of these packages, the Air Force redesignated the radars. The AN/FPS-20A with the AN/GPA-102 became the AN/FPS-66 and the AN/FPS-20A with the AN/GPA-103 became the AN/FPS-67. Over 200 units were built.
General Electric built an FD search radar designed to operate in the Very High Frequency (VHF) at 214 to 236 MHz. There were problems with this radar at the test site at Eufaula, Alabama, in 1960. These problems required many modifications. Additional problems occurred when deployment was attempted in 1961. When the radar finally deployed, bearing problems often occurred due to the eighty-five ton antenna weight. Twelve systems were built between 1958 and 1962.
Westinghouse built an FD search radar designed to operate in the S-band at 2322 to2670 MHz. The radar was designed to have a maximum range of 220 nautical miles and search to an altitude of 150,000 feet. System problems required several modifications at the test platform located at Crystal Springs, Mississippi. Once these problems were solved, the first of twenty units in the continental United States became operational a Charleston, Maine, in 1963. The last unit was installed at Bellefontaine, Ohio, a year later. In the early 1970s, AN/FPS-27 radar stations that had not been shutdown received a modification (solid state circuitry replacing vacuum tubes) that improved reliability and saved on maintenance costs.
Raytheon designed this search radar to operate at 410 to 690 MHz. A test unit was placed at Huoma Naval Air Station (NAS) in Louisiana.
Bendix built this long-range search radar that operated in the L-band.
Designed by Lincoln Laboratory, this huge radar was designed to be compatible with the SAGE system. A prototype was built at Jug Handle Hill in West Bath, Maine. The antenna was 120 feet wide and 16 feet high. Operations began in October 1955. After a period of unexpected clutter, it was determined that the radar received echoes from the aurora borealis (Northern Lights) and this hindered tracking. Although this model was never mass-produced for active use, lessons learned from this radar would continue supporting SAGE system research and development.
This Sperry-built FD long-range search radar was designed to operate at 420 to 450MHz. It was first deployed in December 1960, but problems hampered the program. Four of these units were operational in 1962. The system suffered frequent bearing problems as the antenna weighed seventy tons.
AN/FPS-64, 65, 66, 67, 67A, 72
These radars were modified versions of the Bendix AN/FPS-20 search radar. See theAN/FPS-20 entry.
Bendix built this long-range L-band search radar that was based on the AN/FPS-20. See the AN/FPS-20 entry.
General Electric produced this updated version of the AN/FPS-8 radar in the late1960s. The AN/FPS-88 operated in the L-band at 1280 to 1380 MHz and featured some ECM capability.
This radar was another version of the AN/FPS-20 search radar produced by Bendix. See the AN/FPS-20 entry.
Raytheon modified the AN/FPS-20 radar to create this radar. See the AN/FPS-20entry.
This radar was another modernization of the Bendix AN/FPS-20 radar. See theAN/FPS-20 entry.
This Westinghouse-built search radar operated in the L-band at 1250 to 1350 MHz.
SAGE System Compatible Height-finder Radars
To complement the search radars, height-finding radars were developed to detect aircraft at increasing altitudes. The AN/FPS-6 would serve as the standard model for much of the Cold War.
The AN/FPS-6 radar was introduced into service in the late 1950s and served as the principal height-finder radar for the United States for several decades there after. Built by General Electric, the S-band radar radiated at a frequency of 2700 to 2900 MHz. Between 1953 and 1960, 450 units of the AN/FPS-6 and the mobile AN/MPS- 14 version were produced.
Avco Corporation built this height-finder radar that operated at a frequency of 5400 to 5900 MHz. This radar deployed in the1960s.
General Electric produced this improved version of the AN/FPS-6 height-finder radar in the early
1970s. Operating in the S-band, this high-power radar was capable of detecting targets at a range of over 110 miles.
Martin Marietta produced the high-powered version of the AN/FPS-6 height-finder radar. Seethe AN/FPS-6 entry.
This radar was another modernized version of the ANAFPS-6 height-finder radar. Seethe AN/FPS-6 entry.
Gap-filler radars were designed to cover areas where enemy aircraft could fly low enough to evade detection by distant long-range search radars. Between 1957 and 1962, some 200 AN/FPS-14 and AN/FPS-18 models were built.
This medium-range search radar was designed and built by Bendix as a SAGE system gap-filler radar to provide low-altitude coverage. Operating in the S-band at a frequency between 2700 and 2900 MHz, the AN/FPS-14 could detect at a range of 65 miles. The system was deployed in the late 1950s and 1960s.
This medium-range search radar was designed and built by Bendix as a SAGE system gap-filler to provide low-altitude coverage. The radar operated in the S-band at a frequency between 2700 and 2900 MHz. The system deployed in the late 1950s and 1960s.
This Raytheon gap-filler radar was deployed on the Distant Early Warning (DEW)Line. It operated in the S-band.
North Warning System Radars
The North Warning System replaced the DEW Line system in the late 1970s. New equipment came with the change in system designation. A key component of the modernization was a long-range radar system formally known as Seek Igloo. The system is based around the AN/FPS-117.
This 3-D long-range radar was built by GE Aerospace for use at Alaskan sites and on the Northern Warning System. The radar operated at 1215 to 1400 MHz and had a range of about 220 miles.
This medium-range radar was built by Unisys to serve as an unmanned gap-filler radar on the North Warning System.
Ballistic Missile Early Warning System (BMEWS) Radars
With the advent of ballistic missiles, millions of dollars were spent to research, develop, test, and deploy BMEWS radars.
This radar was a modified AN/FPS-26 height-finder radar produced by Avco Corporation to detect submarine-launched ballistic missiles. The system deployed at seven sites in the 1970s. Six sites were phased out during the early 1980s.The remaining unit continued in operation in the southeast for a few more years to provide coverage over Cuba.
With the Soviet Union apparently making rapid progress in its rocket program, in1954 the United States began a program to develop a tracking radar. General Electric was the contractor and Lincoln Laboratory was the subcontractor. This tracking radar, the AN/FPS-1 7, was conceived, designed, built, and installed for operation in less than two years. Installed at Laredo AFB in Texas, the first AN/FPS-17 was used to track rockets launched from White Sands, New Mexico. The radar was unique; it featured a fixed-fence antenna that stood 175 feet high and 110 feet wide. The transmitter sent out ash pulse at a frequency between 180 to 220 MHz. Units were installed in the late1950s at Shemya Island in the Aleutians and in Turkey. The unit at Shemya subsequently was replaced by the Cobra Dane (AN/FPS-100) radar.
This large radar was built by RCA for use in the BMEWS program and the satellite-tracking program that deployed in the 1960s. The prototype unit operated at Moorestown, New Jersey. Two additional units were installed in Greenland and England. The radar frequency operated in the Ultra High Frequency (UHF) band and could track objects beyond 3,000 miles.
This was a BMEWS program surveillance radar that used a large, fixed-antenna fence system. Two beams were projected from the antenna array. Objects passing through the lower-angled beam provided initial data and warning for the North American Air Defense Command (NORAD). Data produced when the object passed through the upper beam allowed computation of trajectories on launch and target points. The radar operated in the UHF range at 425 MHz. General Electric, Heavy Military Electronics Department, installed these systems at Clear, Alaska, and Thule, Greenland, during the early1960s.
This UHF, 3-D, phased-array radar was designed by Bendix for satellite tracking. Built in the early 1960s at Eglin AFB in Florida, it was the first phased-array unit in the United States. A fire destroyed the first model in 1965. A rebuilt model became operational in 1969. The southward-sloped structure contained a square transmitter face placed alongside a larger octangular receiving face. The transmitter operated at a UHF frequency of 442 MHz. The AN/FPS-85 was also used to detect submarine-launched ballistic missiles.
This improved version of the AN/FPS-49 tracking radar was used in the BMEWS Program. Built by RCA, this radar was installed at Clear, Alaska, in the late 1960s. The radar operated in the UHF band around 425 MHz and had a range of over 3,000 miles.
AN/FPS-108 (Cobra Dane)
Cobra Dane was a large single-faced, phased-array radar built by Raytheon in the 1970s on Shemya Island in the Aleutians. As the main component of the Cobra system, the radar had the primary role of providing intelligence on Soviet test missiles fired at the Kamchatka peninsula from locations in southwestern Russia. Other components of the Cobra system included the ship-based Cobra Judy phased-array radar and the aircraft-based Cobra Ball and Cobra Eye radars. In addition to determining Soviet missile capabilities, Cobra Dane had the dual secondary role of tracking space objects and providing ballistic missile early warning. The radar antenna face of the building measured about ninety feet in diameter and contained some 16,000 elements. The L-band radar had a range of 2,000 miles and could track space objects as far as 25,000 miles away.
Raytheon built the PAVE PAWS phased-array, missile-warning radar deployed during the early 1980s. At the four continental United States sites, the ninety foot diameter circular panel radars were mounted on two walls of a triangular-shaped pyramid structure. The antenna operated at a frequency of 420 to 450 MHz. PAVE PAWS could detect targets at ranges approaching 3,000 miles.
Designed and built by GE Aerospace, the OTH-B radar was deployed on the east and west coasts in the 1980s. The system reflected the radar beam off the ionosphere to detect objects from ranges of 500 to nearly 2,000 miles. The transmitter arrays operated at frequencies between 5 and 28 MHz. Fixed transmitter and receiving antenna arrays were separated by a distance of 80 to 120 miles.
The acronym, PARCS, stands for Perimeter Acquisition Radar attack Characterization System. This huge structure was built as the main sensor for the Army's Safeguard missile system that deployed north of Grand Forks, North Dakota. Upon shut down of Safeguard in 1976, the Air Force took over the huge UHF phased-array radar for use in tracking ballistic missiles and objects in space.
Federal Aviation Administration (FAA) Radars
Beginning in the late 1950s, the Civil Air Administration (predecessor to the FAA) and the DoD began to cooperate to reduce duplication. By the late 1980s most radars performing air search for the military were operated by the FAA in the joint surveillance program. Because it is a civilian agency, the FAA uses a different radar designation system.
This Raytheon-built Air Route Surveillance Radar (ARSR) was used by the FAA Authority Radar beginning in 1958. It operated on a L-band frequency of 1280 to 1350MHz with a maximum range of 200 miles.
Developed by Raytheon in the 1960s as a replacement for the ARSR-1, this radar also operated in the L-band and had a similar maximum range to the ARSR-1.
This Westinghouse-built search radar was used by the FAA in the Joint Surveillance System (JSS). The radar operated in the L-band at 1250 to 1350 MHz and detected targets at a distance beyond 240 miles. The D model had height-finder capability.
The FAA began installing this Westinghouse-built 3-D air surveillance radar in the1990s for the JSS system. By the late 1990s this radar will have replaced most of the 1960s-vintage AN/FPS-20 variant search radars.