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AN/FPS-95 “Cobra Mist”

Description of the radar set, tactical-technical characteristics

Figure 1: AN/FPS-95 “Cobra Mist”

Figure 1: AN/FPS-95 “Cobra Mist”, located in Suffolk, England (52°06'23.1" N   1°34'55.6" W)
(© 2010 User:Hohum, Wikipedia)

frequency: 6 … 40 MHz
pulse repetition time (PRT):
pulse repetition frequency (PRF): 10 … 160 Hz
pulsewidth (τ): 250 … 6 000 µs
receiving time:
dead time:
peak power: 3.5 MW
average power: 300 kW
instrumented range: 500 … 2 000 NM
(≙ 920 … 3 700 km)
range resolution:
hits per scan:
antenna rotation:

AN/FPS-95 “Cobra Mist”

AN/FPS-95 “Cobra Mist” (british designator: System 441A) was operating in HF-band Over-The-Horizon radar. It operated from the late 1960’s until 1973 and was located in Suffolk, England.

The antenna consisted of 18 individual log-periodic antennas which were arranged radially like spokes in a wheel from a central feed point. They consisted of 620 m long strings supported by masts from 13 m to 59 m high. The active dipole elements hanging from these strings were cross-mounted to provide both horizontal and vertical polarization. The antennas had a radial spacing of 8 degrees and 40 minutes and covered a bearing range of 19.5° to 110.5°. A large mesh screen was located under the antenna to improve conductivity for the ground wave transition. The antenna’s gain was 25 dB.

Nevertheless, due to a consistent and still unknown source of environmental noise, the radar never became fully operative leading to the shutting down of the project in 1973.