Alexanderson with a radio transmitter at Riverhead, New York, USA. Ernst Frederick Werner Alexanderson (1878-1975), Swedish-US engineer, is best-known for designing the Alexanderson alternator, which made voice radio broadcasts possible. This photograph is from a collection of unpublished images, dating from the 1860s to the 1920s, taken for 'The Pageant of America: A Pictorial History of the United States' (1925-1929).