Valdemar Poulsen, Danish engineer (d. 1942)
Valdemar Poulsen (23 November 1869 – 23 July 1942) was a Danish engineer who made significant contributions to early radio technology. He developed a magnetic wire recorder called the telegraphone in 1898 and the first continuous wave radio transmitter, the Poulsen arc transmitter, in 1903, which was used in some of the first broadcasting stations until the early 1920s.