Peder Oluf Pedersen

Peder Oluf Pedersen (19 June 1874 – 30 August 1941) was a Danish engineer and physicist. He is notable for his work on electrotechnology, his cooperation with Valdemar Poulsen on the developmental work on  Wire recorders, which he called a  telegraphone, the arc converter known as the Poulsen Arc Transmitter, and his work on electrical currents in the ionosphere.

Pedersen became a professor of telegraphy, telephony and radio in 1912. He became principal of the College of Advanced Technology (Den Polytekniske Læreanstalt) in 1922, a title he held until his death. He was a Fellow of the American Institute of Electrical Engineers and was a member of the British Institution of Electrical Engineers. In 1915 he became a Fellow of the Institute of Radio Engineers.

The first expression for the Pedersen current was formulated by Pedersen from in his 1927 work "The Propagation of Radio Waves along the Surface of the Earth and in the Atmosphere",  where he pointed out that the geomagnetic field means that the conductivity of the ionosphere is anisotropic.