The Duga (Russian: Дуга, lit. 'arc' or 'curve') was an over-the-horizon radar designed and utilized in the Soviet Union from 1972 to 1989. Two deployments of duga radar are known, one in Liubech-1 and Chernobyl-2, and a second near Komsomolsk-on-Amur.
DUGA (Russian: Дуга; Soviet designation 5Н32) was a high-frequency (HF, 3–30 MHz) over-the-horizon (OTH) early-warning radar family fielded by the USSR between 1976 and 1989 to detect intercontinental ballistic missile (ICBM) launches at ranges of 600–3,000 km using ionospheric skywave propagation. The USSR completed two full-scale operational chains: one in northern Ukraine (with a receiver at “Chernobyl-2” and a transmitter near Liubech) and one in the Russian Far East (with a receiver near Bolshaya Kartel and a transmitter near Lian-2). Large experimental/prototype builds near Mykolaiv (Ukraine) preceded them. DUGA’s distinctive ~10 Hz, BPSK-coded pulses generated the worldwide “Russian Woodpecker” interference heard across shortwave from 1976 to 1989 and extensively reverse-engineered by radio observers. Today, only the Chernobyl-2 receive arrays remain standing; the Far East and Mykolaiv sites have been dismantled. Modern Russian OTH programs (e.g., 29B6 “Container”) continue the lineage.
System Architecture
DUGA was a bi-static HF radar: a high-power transmitter steered a wideband, phase-coded pulse toward an ionospheric reflection point. After one or more skywave “hops,” ground/sea backscatter and target-modulated echoes were received hundreds to thousands of kilometers away at a separate, very large phased-array receiving site. Signal processing used matched filtering/correlation against the transmitted pseudo-random code to recover echoes in heavy clutter and variable ionospheric conditions. The arrays were optimized in two sub-bands (“low-frequency” 4–14 MHz; “high-frequency” 8–30 MHz), with broadside cage-dipole elements and reflector wires to produce a narrow horizontal beam and elevation control via frequency and phasing.
Typical On-air Signature
- Pulse repetition ~10 Hz (“woodpecker” tapping).
- BPSK (binary phase-shift keying) intra-pulse modulation using a 31-bit pseudo-random sequence; bit width ≈100 µs → pulse length ≈3.1 ms.
- Occupied bandwidth of several kHz to ~20 kHz depending on mode/frequency; frequent frequency hops across 3–30 MHz.
Contemporary hobbyist and engineering campaigns documented these parameters (Monitoring Times, Wireless World, ENIGMA community) triangulating the sites and de-spreading the waveform.
