AN/FPS-18 Radar

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The AN/FPS-18 was a medium-range search radar used by the United States Air Force Air Defense Command.

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-18 could detect at a range of 65 miles.

The system was deployed in the late 1950s and 1960s at unmanned radar facilities (called "Gap Fillers") designed to fill the low-altitude gaps between manned long-range radar stations. Gaps in coverage existed due to the curvature of the Earth, mountains, hills, valleys, rivers, and so forth.

The typical unmanned gap-filler radar annex consisted of a small L-shaped cinder-block building, with the radar equipment and the data-transmission equipment in one section and one or more diesel generators in the other section. These unmanned gap-filler sites generally had a three-legged radar tower about 85 feet tall where the AN/FPS-18 Radar was mounted inside a radome.

In accordance with the Joint Electronics Type Designation System (JETDS), the "AN/FPS-18" designation represents the 18th design of an Army-Navy electronic device for fixed ground search radar.{{cite book|last=Winkler|first=David F.|title=Searching the Skies: The Legacy of the United States Cold War Defense Radar Program|chapter=Radar Systems Classification Methods|page=73|publisher=United States Air Force Headquarters Air Combat Command|location=Langley AFB, Virginia|year=1997|lccn=97020912|url=https://nuke.fas.org/guide/usa/airdef/1997-06-01955.pdf}} {{source-attribution}}{{cite book|author=Avionics Department|title=Electronic Warfare and Radar Systems Engineering Handbook|edition=4|chapter=Missile and Electronic Equipment Designations|pages=2–8.1|publisher=Naval Air Warfare Center Weapons Division|location=Point Mugu, California|year=2013|url=https://apps.dtic.mil/sti/tr/pdf/ADA617071.pdf}} The JETDS system also now is used to name all Department of Defense electronic systems.