English: Antenna of the Duga-1 (Дуга-1) over-the-horizon (OTH) radar system, Chernobyl, Ukraine, part of the Soviet ABM early-warning network. It is known in the West by the NATO designation "Steel yard". Its powerful signal, called the "Woodpecker" because it sounded like a tapping noise in radio receivers, was notorious for interfering with radio and television transmissions. The pairs of cylindrical cages at right are the driven elements, fed at their center by vertical feed lines. Behind them is a vertical reflector screen of wires, just visible in center.