Duga-3 ("duga" means "arc") or "Steel Yard" was a Soviet experimental over-the-horizon radar (OTH) system. It was developed for the Soviet ABM early-warning network. The system operated from 1976 to 1989.
Two stations of Duga-3 were installed: a western system around Chernobyl and an eastern system in Siberia.
The transmitter for the western Duga-3 was located a few kilometers southwest of Chernobyl (south of Minsk, northwest of Kiev). The receiver was located about 50 km northeast of Chernobyl (just west of Chernihiv, south of Gomel).