Duga

Duga is the Russian designation for a type of over-the-horizon radar system developed by the Soviet Union. These massive radar installations were designed to detect incoming ballistic missiles and aircraft from thousands of kilometers away. The most famous and widely recognized Duga installation was located near Chernobyl in the Ukrainian SSR. Its distinctive and persistent broadcasting sound led to it being nicknamed the "Russian Woodpecker" by Western observers.

The Duga radar operated in the shortwave radio spectrum. Its immense size was a necessity due to the principles of over-the-horizon radar, which bounces signals off the ionosphere to achieve long ranges. The Chernobyl Duga site, for example, consisted of two enormous antenna arrays, one stretching over 700 meters in length and standing 150 meters high. The sheer scale of these structures made them highly visible and contributed to their notoriety.

During its operational period, the Duga radar generated significant interference on various radio frequencies worldwide. This interference was disruptive to civilian radio communications and amateur radio operators. Despite its intended military purpose, the Duga system's widespread signal disruption became a prominent feature of the Cold War's technological arms race. The Chernobyl Duga radar ceased operations in the late 1980s, with its decommissioning attributed to a combination of factors including rising operational costs and the Chernobyl disaster itself. Other Duga sites existed in different locations within the Soviet Union, though the Chernobyl one remains the most extensively documented and discussed.