AN/FPS-19 DEW-Line Radar.

The Primary Search Radar for DEW-Line sites in Canada and Alaska was the AN/FPS-19, a high-power L-Band search radar consisting of two identical radar sets feeding a dual (back-to-back) antenna.

Photograph by Jeroen Steenbeek unless stated otherwise. For remarks, concerns or contributions contact me (

The AN/FPS-19 radar was based on the earlier AN/TPS-1D system, which operated between 1220 to 1350 MHz, and used the Raytheon 5J26 magnetron as the main RF power source. It was rated at 2 microseconds pulse duration and 400 pulses per second, which yields a duty cycle of 0.0008. However, the listed duty cycle is shown as 0.001. That is probably a "maximum" figure. Likewise, the peak power output of the 5J26 was 500 kW, but the radar is listed as having an average power output of 500 watts. That again is probably a "maximum."

The AN/FPS-19 differed from the AN/TPS-1D in that it used two transmitters, for a total average power output of 1000 watts. The main technical design difference was that it had two antennas, situated back-to-back, one for each radar (500 watts each). One produced a pencil beam for long-range precision detection, while the other had a cosecant -squared antenna for general search with a wider beam.

Source: Raytheon Corporation archives