SAGE System Frequency-Diversity Radars

In June 1955 Rome Air Development Center, Griffiss Air Force Base, New York, let design-study contracts for six new ground control of intercepts (GCI) radars, each to operate in a segment of the frequency range 214 to 5900 MHz. At that time, Air Force GCI radars were moving through attrition toward occupancy of only two frequency bands: the FPS-7 surveillance and height-finding radar with stacked beams operated at 1300 MHz, and the FPS-6 height-finding radar operated at 2900 MHz. These two radars, lineal descendants of radars developed during World War II, constituted what amounted to a single-frequency air-defense radar system. The frequency-diversity (FD) radar program was to reverse that trend.

The spread of operating frequencies to be provided by the FD radar program promised to make it more costly in terms of payload for an airborne intruder to penetrate and survive in the defensive radar environment, as discussed in the main text. At the same time, the new program would enhance the Air Force's GCI capabilities, in particular, its ability to feed high-quality data to the Semi-Automatic Ground Environment (SAGE) air-defense system.

Five of the six proposed radars were selected for prototype development, and four were produced in quantity. These five systems in their prototype forms were installed for testing and evaluation at operational Air Force sites in Alabama, Louisiana, and Mississippi, part of the Mobile, Alabama, Air-Defense Sector. Their test programs began in 1959.

In addition, the GLA-8 signal processing system, built by Airborne Instrument Laboratory, was an important common adjunct to each frequency-diversity radar. This equipment included a special anti-jamming console used by the radar's human counter-countermeasures (CCMs) operator. As discussed in the main text, CCMs such as frequency hopping and PRF jitter/stagger are useful in reducing the effectiveness of both passive countermeasures (chaff, for example) and active countermeasures (spot and noise jamming, and signal repeaters). The wise use of the many features of a highly flexible FD radar required special skills and sophisticated technological support.

From “Long-Range UHF Radars for Ground Control of Airborne Interceptors” by William W. Ward and F. Robert Naka, in the Lincoln Laboratory Journal, Volume 12, Number 2.

Frequency-Diversity Radar Sites

Location	Search Radar	Height Finder Radar	SLBM Radar	Closed	Notes
Aiken Air Force Station	FPS-7C	FPS-26A		1975
Ajo Air Force Station	FPS-7C	FPS-26		1969
Antigo Air Force Station	FPS-35	Non FD		1977
Almaden Air Force Station	FPS-24	Non FD		1980
Baker Air Force Station	FPS-35	Non FD		1968
Baudette Air Force Station	FPS-24	FPS-26A		1979
Benton Air Force Station	FPS-35	FPS-26		1975
Blaine Air Force Station	FPS-24	FPS-26A		1979
Boron Air Force Station	FPS-35	FPS-26A		1975
Bucks Harbor Air Force Station	FPS-24	FPS-26A		1979
Calumet Air Force Station	FPS-27	FPS-26A		1988
Cambria Air Force Station	FPS-7C/FPS-107V	FPS-26A		1980
Cape Charles Air Force Station	FPS-7B	FPS-26A		1981
Caswell Air Force Station	FPS-7C/FPS-107	FPS-26A		1980
Chandler Air Force Station	FPS-27	FPS-26		1969
Charleston Air Force Station	FPS-27A	FPS-26A	FSS-7	1980	Det 6, 14 MWS
Cottonwood Air Force Station	FPS-24	Non FD		1965
Custer Air Force Station	FPS-66	FPS-26A		1965
Cut Bank Air Force Station	FPS-66	FPS-26A		1965
Empire Air Force Station	FPS-7	FPS-26A		1979
Eufaula Air Force Station	FPS-24	FPS-26A	FSS-7	1968
Fallon Air Force Station	FPS-35	Non FD		1975
Finland Air Force Station	FPS-27	FPS-26A		1980
Finley Air Force Station	FPS-35	Non FD		1979
Fort Fisher Air Force Station	FPS-7C/FPS-107V	FPS-26A	FSS-7	1988	Det 5, 14 MWS
Fort Lawton Air Force Station	ARSR-1C	FPS-26A		1966
Fortuna Air Force Station	FPS-35	FPS-26A		1979
Gibbsboro Air Force Station	FPS-27	FPS-26A		1984
Highlands Air Force Station	FPS-7	FPS-26A		1984
Hutchinson Air Force Station	FPS-66A	FPS-26A		1968
Klamath Air Force Station	FPS-27	FPS-26A		1968
Las Vegas Air Force Station	FPS-27	FPS-26A		1969
Lockport Air Force Station	FPS-7/FPS-107	FPS-26		1979
Laredo Air Force Station			FSS-7	1974	Det 8, 14 MWS
Lyndonville Air Force Station	FPS-27*	FPS-26		1963	FPS-27 tower built but the set was not installed
MacDill Air Force Base Radar Site	FPS-7E	FPS-26A	FSS-7	1980	Det 7, 14 MWS HQ Det 1, 20 MWS 1981
Makah Air Force Station	FPS-7A/FPS-107V1	FPS-26A		1988
Malmstrom Air Force Base Radar Site	FPS-24	Non FD		1969
Manassas Air Force Station	FPS-35	FPS-26A		1965
Mill Valley Air Force Station	FPS-7C	FPS-26A	FSS-7	1980	Det 3, 14 MWS
Minot Air Force Station	FPS-27	FPS-26A		1979
Montauk Air Force Station	FPS-35	FPS-26		1981
Mount Hebo Air Force Station	FPS-24->FPS-27	FPS-26A	FSS-7	1969	Det 2, 14 MWS 1980
Mount Laguna Air Force Station	FPS-7E	FPS-26A	FSS-7	1981	Det 4, 14 MWS 1980
Naselle Air Force Station	FPS-67	FPS-26A
North Bend Air Force Station	FPS-7/FPS-107V2	FPS-26A
North Charleston Air Force Station	FPS-27	FPS-26
North Truro Air Force Station	FPS-7/FPS-107	FPS-26A
Oakdale Air Force Station	FPS-24	FPS-26A		1969
Opheim Air Force Station	FPS-7C/FPS-107	FPS-26A
Othello Air Force Station	FPS-7C/FPS-107	FPS-26A
Point Arena Air Force Station	FPS-24	FPS-26A		1976
Port Austin Air Force Station	FPS-24	FPS-26A		1982
Roanoke Rapids Air Force Station	FPS-27	FPS-26A
Saint Albans Air Force Station	FPS-7C	FPS-26A
San Pedro Hill Air Force Station	FPS-27	FPS-26A
Saratoga Springs Air Force Station	FPS-27	FPS-26A
Sault Ste Marie Air Force Station	FPS-35	FPS-26A		1979
Savannah Air Force Station	FPS-67B	FPS-26
Selfridge Air Force Base Radar Site	FPS-35	FPS-26A		1974
Sundance Air Force Station	FPS-7C	FPS-26
Thomasville Air Force Station	FPS-35	Non FD		1969
Watertown Air Force Station	FPS-27	FPS-26A
Waverly Air Force Station	FPS-27	FPS-26A
Winston-Salem Air Force Station	FPS-24	FPS-26		1970