Over-the-horizon radar
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Over-the-horizon radar, sometimes called beyond the horizon radar, is a type of radar system with the ability to detect targets at very long ranges, typically hundreds to thousands of kilometres, beyo
How a skywave OTH radar works: A powerful shortwave signal from a large transmitting antenna (left) reaches a target beyond the horizon by refracting off the ionosphere, and the echo signal from the target (right) returns to the receiving antenna by the same route. In practice, the beams are much closer to the horizon than shown here.
MADRE over-the-horizon radar at the NRL's Chesapeake Bay Detachment
Duga radar array, near Chernobyl
Coverage of the three U.S. Navy ROTHR stations in Texas, Virginia, and Puerto Rico
Duga radar
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Duga was an over-the-horizon radar system used in the Soviet Union as part of its early-warning radar network for missile defence. It operated from July 1976 to December 1989. Two operational Duga rad
Over-the-horizon radar
…also studied OTH systems. The first experimental model appears to be the Veyer (Hand Fan), which was built in 1949. The next serious Soviet project was Duga, built outside Mykolaiv on the Black Sea coast near Odessa in Ukraine. Aimed eastward, Duga first ran on 7 November 1971, and was successfully used to…
Duga-1 array within the Chernobyl Exclusion Zone. The array of pairs of cylindrical/conical cages on the right are the active elements, fed at the facing points with a form of ladder line suspended from stand-off platforms at top right. A backplane axial reflector of small wires is visible left of centre, most clearly at the bottom of the image. The elements appear to be a modified type of cage or bi-conical dipole providing wide operating bandwidth.
Steel structure of Duga-1 from below