FPS-18

Gap Filler Search Radar

During the Cold War, especially in the early to mid 1950s, there was great concern for the security of North American airspace. The RCAF, the Canadian component of the joint Canada-USA North American Air Defense Command (NORAD), decided to construct a number of long range radar stations, known as the Pinetree Line, located coast to coast in Canada. While these long range radar stations provided good coverage, the technology of the time did not provide total coverage. It was suspected that enemy aircraft could fly low to avoid detection by the Pinetree Line radar stations. With this in mind, the Canadian government committed itself to a Gap Filler program in October 1959. The AN/FPS-18 gap filler radars were to be placed in unmanned Gap Filler Annex (GFA) locations. An estimated 45 of these radars, with detection range of about 65 miles, were to be positioned in the eastern provinces of the country.

This medium-range search radar was designed and built by Bendix as a SAGE system gap-filler to provide low-altitude coverage. The radar operated in the S-band at a frequency between 2700 and 2900 MHz. The system deployed in the United States during the late 1950s and 1960s. Ironically, the system was never deployed in Canada.

FPS-18 Gap Filler Complex at Jeffersonville, GA in November 1965.
It is assumed that the RCAF Gap Fillers would have been very similar.
Courtesy Tom Page.