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Description of the radar set, tactical-technical characteristics
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Figure 1: Former SRE-LL site near Bremen
(© 1998 DFS Deutsche Flugsicherung, H.-J. Koch)

frequency: 1250 - 1350 MHz
pulse repetition time (PRT): 2.5 ms
pulse repetition frequency (PRF): 400 Hz (staggered)
pulsewidth (τ): 2.5 µs
receiving time:
dead time:
peak power: 5 MW
average power: 9 kW
instrumented range: 200 nautical miles (
range resolution: < 400 m
hits per scan:
antenna rotation: 2 - 7.5 rpm


The SRE-LL radar (Surveillance Radar Equipment, twin-L-Band) was developed by AEG Telefunken since 1969, the prototype was installed near Bremen (see Figure). Until 1974 five more series were delivered for a gapless radar coverage in the former western Germany. SRE-LL radars remained operational until the mid-90'ies.

The use of two antennas in back-to-back configuration (the so-called “Janus-Design”) gave a better information renewal time for a given revolution rate. The reflector dimensions were 14.5 • 9 m. Both antenna halves generate a Cosecant squared antenna pattern. The lower edge of the pattern was increased by a Pencil-Beam blanked in the inner range around the radar. The total weight of the rotating parts of the antenna was 60 tons.