Alan Blumlein, English engineer, developed the H2S radar (died 1942)

Alan Dower Blumlein was an English electronics engineer, notable for his many inventions in telecommunications, sound recording, stereophonic sound, television and radar. He received 128 patents and was considered one of the most significant engineers and inventors of his time.

H2S was the first airborne, ground scanning radar system. It was developed for the Royal Air Force's Bomber Command during World War II to identify targets on the ground for night and all-weather bombing. This allowed attacks outside the range of the various radio navigation aids like Gee or Oboe, which were limited to about 350 kilometres (220 mi) of range from various base stations. It was also widely used as a general navigation system, allowing landmarks to be identified at long range.