The Wullenweber (the original name introduced by Dr. Hans Rindfleisch was Wullenwever) is a type of Circularly Disposed Antenna Array (CDAA) sometimes referred to as a Circularly Disposed Dipole Array (CDDA). It is a large circular antenna array used for radio direction finding. It was used by the military to triangulate radio signals for radio navigation, intelligence gathering and search and rescue. Because its huge circular reflecting screen looks like a circular fence, the antenna has been colloquially referred to as the elephant cage. The term wullenwever was the World War II German cover term used to identify their secret CDAA research and development program; its name is unrelated to any person involved in the program. History Origin in World War II Germany Wullenweber technology was developed by the German navy communication research command, Nachrichtenmittelversuchskommando (NVK) and Telefunken during the early years of World War II. The inventor was NVK group leader Dr. Hans Rindfleisch, who worked after the war as a Technical Director for the northern Germany official broadcast (Norddeutscher Rundfunk (NDR)). Technical team leaders were Dr. Joachim Pietzner, Dr. Hans Schellhoss, and Dr. Maximilian Wächtler. The last was a founder of Plath GmbH in 1954 and later a consultant to both Plath and Telefunken. The first Wullenwever was built during the war at Skibsby, north-east of the city of Hjørring (in German: Hjörring), Denmark (). It used 40 vertical radiator elements, placed on the arc of a circle with a diameter of . In an inner circle, 40 reflecting elements were placed behind the radiator elements, suspended from a structure of circular wooden support poles with a diameter of 112.5 meters. To more easily obtain true geographic bearings, the north and south elements were placed exactly on the north-south meridian. Post-war development Although Pietzner, Schellhoss, and Wächtler retired in West Germany, some of their second-echelon technicians were taken to the USSR after the war. At least 30 Krug (Russian for circle) arrays were installed all over the Soviet Union and allied countries in the 1950s, well before the U.S. military became interested and developed their own CDAAs. Several Krugs were installed in pairs less than 10 kilometers of each other, apparently for radio navigation purposes. At least four Krugs were installed near Moscow; just to the north, east and south () of the city. The Krugs were used to track the early Sputnik satellites, using their 10 and