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FPS-90 Long Range Height Finder Radar Set - A Long Range Height Finder Radar set developed at RADC and built by General Electric. The FPS-90 was a long range, high power, air transportable, height finding radar used in conjunction with a long range search radar set. The basic components for the FPS-90 came from the FPS-6, FPS-6A and FPS-6B. The differences with the FPS-6 series were:

  • Removal of the variable nod functionality in the FPS-6B models.
  • Replacement of the magnetron with a higher power QK-338A magnetron.

The FPS-90s (and FPS-6s) were used in the SAGE System to provide height data for targets selected by the direction center. The direction center would preposition the height-finder through the FST-2 and an operator would verify the target and transmit the correct altitude back to the direction center. The Range Height Indicators (RHI) of the FPS-90 were used to find the target and a cursor would be positioned at the correct altitude.

FPS-90 Height Finder Radar

FPS-90 Height Finder Radar
Element Value Notes
Nomenclature FPS-90
Origins AN/FPS-6
Variants FPS-507
Manufacturer General Electric
Type Height Finder
Number Made
IEEE Band S Band
Frequency 2700 - 2900 MHz
PRF 300-400 pps
Pulse Width 2 to 3 usec
Rotation Speed Variable
Power 4.5 MW peak power
Range 220 nmi Long Range
Altitude 75,000 feet
Elevation Accuracy +/- 1000 ft.
FPS-6 Radar Set Antenna on Tower.

See Also:


  • Winkler, David F., Searching the Skies: the Legacy of the United States Cold War Defense Radar Program, USAF Hq Air Combat Command, 1997, 192 pages, Pdf.
  • MIL-HDBK-162A, 15 Dec 1965.


  • Bad Links /museum/parseequip.php?html=fps-90.html&type=equip_html FPS-90]

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