Keywords: blackandwhite monochrome black and white NH 41640: First Rotating Beam Radar (200 megacycle radar used for transmitting and receiving) Developed by the U.S. Naval Research Laboratory (NRL) in 1937. Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command. (2016/02/29). NH 41640: First Rotating Beam Radar (200 megacycle radar used for transmitting and receiving) Developed by the U.S. Naval Research Laboratory (NRL) in 1937. Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command. (2016/02/29). |