Westinghouse AN/FPS-27 Radar

The AN/FPS-27 Radar was a Long Range search radar used by the United States Air Force Air Defense Command.

AN/FPS-27

Westinghouse AN/FPS-27 Radar
Country of origin	United States
Introduced	1963 (1963)
Type	Surveillance and Height Finding
Frequency	2322 to 2670 MHz
PRF	selectable between 226 and 288
Pulsewidth	6.5 micro seconds
RPM	5 RPM
Range	220 nmi (410 km; 250 mi)
Altitude	150,000 ft (46,000 m)
Power	15,000,000 Watts peak; 30,000 Watts average

Westinghouse built a Frequency Diverse (FD) search radar designed to operate in the S-band from 2322 to 2670 MHz. The radar was designed to have a maximum range of 220 nmi (410 km; 250 mi) and search to an altitude of 150,000 ft (46,000 m).

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-Automated Ground Environment (SAGE) 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 (solid state receiver circuitry replacing vacuum tubes) that improved reliability and saved on maintenance costs. The upgraded radars were designated AN/FPS-27A.