AN/FPS-27
The AN/FPS-27 Radar was a long-range early warning radar used by the United States Air Force Air Defense Command.
Westinghouse Electric Corporation built a frequency diverse search radar designed to operate in the S-band from 2322 to 2670 MHz. The radar was designed to have a maximum range of and search to an altitude of.
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 at Charleston, Maine, in 1963. The last unit was installed at Bellefontaine, Ohio, a year later. All AN/FPS-27 radars were installed at sites which had AN/FPS-6, AN/FPS-26, or AN/FPS-90 height finder radars. The 3-D functionality of the AN/FPS-27 was not available to the AN/FYQ-47 Common Digitizer for use in the Semi-Automatic Ground Environment system.
The 3-D functionality was possible through the use of a "vertically stacked beam" radiating feedhorn into the parabolic reflector. The received radar return was detected in a single or adjacent feedhorn which the radar receiver calculated a relative position in elevation.
In the early 1970s, AN/FPS-27 radar stations that had not been shut down received a modification that improved reliability and saved on maintenance costs. The upgraded radars were designated AN/FPS-27A.
In accordance with the Joint Electronics Type Designation System, the "AN/FPS-27" designation represents the 27th design of an Army-Navy electronic device for fixed ground search radar. The JETDS system also now is used to name all Department of Defense electronic systems.