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FPS-117 Long Range 3D Radar Set - A 3D Radar set for Air surveillance/defense and air traffic control. Originally built by General Electric now Lockheed Martin.

This radar is a solid-state, L-band, 3-D system designed to provide long-range aircraft range, azimuth and height detection. The US and Canada have deployed 15 radars in Alaska, 11 in Canada, and one each in Hawaii, Puerto Rico and at Hill Air Force Base in Utah. Hill AFB is the logistics center for the FPS-117 and the facility there is known as Hill Air Force Base Engineering Facility (E-FAC). The radars are part of the Air Force's Atmospheric Early Warning System.

This radar is classed as minimally attended, designed to be remotely operated and diagnosed from maintenance control centers. Travel to remotely located sites is limited to periodic maintenance and emergency repairs.

Hill Air Force Base FPS-117 Radar Site.

Radar System

The 24' by 24' planar antenna array rotates on a pedestal usually at the top of a tower covered with a rigid radome. The FPS-117 has a pencil beam capability that allows customization of beam patterns to deal with terrain and clutter issues. The pencil beam architecture offers a -6 degree “look down” capability from elevated sites to detect aircraft at lower levels and a 20-degree upper view.

The planar antenna is made up of 44-row transceivers, 44-row feed assemblies, four-column feed assemblies, and 12-row power supplies. The exciter and final receiver are mounted at the base of the antenna itself.

Beacon System

A separate beacon system with Mode 4 and Mode S Identification Friend or Foe (IFF) systems is usually provided. The beacon antenna is mounted on top of the FPS-117 radar sail.

Essential Parts Replacement Program (EPRP)

In 2011 the U.S. Air Force awarded Lockheed Martin $46.8 million in contract options to begin modernization of 29 long-range radars. Under the EPRP contract, Lockheed Martin was to modernize 15 radars in Alaska, 11 in Canada, and one each in Hawaii, Puerto Rico and Utah, all part of the Air Force's Atmospheric Early Warning System. The Utah radar was the FPS-117 at the Hill Air Force Base Radar Site.

By 2011 the FPS-117 radars, which were originally installed in the 1980s, suffered from excessive parts obsolescence and diminishing manufacturing sources. The EPRP program was established to eliminate obsolete components and to ensure continued supportability through 2025. The modifications also provided the hardware necessary for the eventual implementation of Mode 5 IFF.

The program replaced four major subassemblies on the FPS-117: the Maintenance and Control System, the Beacon system, the Uninterruptable Power Supply/Communications Rack, and Local Control Terminals, which allow remote monitoring, troubleshooting, and control of the radars. The modifications reduced the line-replaceable unit count by approximately 80 percent, easing maintenance and the number of parts on the shelf.

More than 25 radar systems were upgraded, including the Hill AFB Engineering Facility, the last site in Hawaii was returned to service in late June 2015 after all the site operations and maintenance personnel had been trained.

FPS-117 3D Radar

FPS-117 3D Radar
Element Value Notes
Nomenclature FPS-117
Variants FPS-117(V)4
Manufacturer General Electric
Lockheed Martin
Type 3D
Number Made 32~
North Warning System
IEEE Band L Band
Frequency 1,215 - 1,400 MHz
PRF 241
Pulse Width 51.2 μsec (short range)
409.6 μsec (long range)
Rotation Speed 5 or 6 rpm
Power 24.75 kW Peak
Range 5 to 250nm ±0.25nm Long Range
Altitude 100k ft
Introduced FY1980
Production (12)
Cost est $14-$15 Million each
FPS-117 Model at North Bay CFB Museum. The Beacon Antenna is shown at the Top of the Sail.

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