The Alexanderson alternator, a high-frequency radio transmitter that enabled early intercontinental communication, represented a pivotal advancement in electrical engineering. Ernst Alexanderson, the Swedish-born inventor behind this technology, spent decades at General Electric and the Radio Corporation of America, securing 345 United States patents and fundamentally shaping early twentieth-century wireless transmission and television development.
Early Career and Education
Born in 1878 within the Uppsala Cathedral Assembly, Alexanderson pursued technical training at the Royal Institute of Technology and the Technische Universität Berlin. In 1902, he moved to the United States to begin his career as an electrical engineer and inventor. Shortly after joining General Electric, he took on the challenge of developing a continuous wave transmitter for researcher Reginald Fessenden. To safely test the high-speed rotors necessary for this device, he constructed a fortified sandbagged bunker, successfully delivering a 50 kHz alternator by 1906.
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The alternator facilitated the first experimental audio broadcast on Christmas Eve in 1906, when Fessenden transmitted music across the East Coast. Beyond radio, Alexanderson transitioned into television engineering. In 1927, he received the first domestic television broadcast at his Schenectady home and subsequently coordinated sound and visual components for the drama, The Queen's Messenger. By 1930, he held public demonstrations of a large-screen television system using closed-circuit channels.
Wartime Innovation and Institutional Critique
During the Second World War, Alexanderson developed the amplidyne, a direct current amplifier utilized for the precision control of anti-aircraft weaponry. Throughout his tenure in industrial research, he observed shifts in the patent system, noting that these structures functioned primarily to protect large institutions rather than the independent inventors they were originally designed to assist. He continued his technical output until his final patent application in 1968.
Fast facts
- Born: 1878, Uppsala Cathedral Assembly
- Died: 1975, Schenectady
- Citizenship: United States and Sweden
- Total US patents held: 345
- IEEE Medal of Honor recipient: 1919
- Edison Medal recipient: 1944
- National Inventors Hall of Fame induction: 1983
- Buried: Vale Cemetery and Vale Park
Questions readers ask
Did the Alexanderson alternator remain in use throughout the twentieth century?
No, it was the primary technology for intercontinental radiotelegraphy until the 1930s, when it was superseded by vacuum tube transmitters.
Is there any remaining evidence of his original radio technology?
Yes, the Grimeton radio station near Varberg, Sweden, houses the only functioning Alexanderson transmitter and was designated a UNESCO World Heritage Site in 2004.
Achievements
- National Inventors Hall of Fame — 1983
- Educated at Royal Institute of Technology and Technische Universität Berlin
- Worked as electrical engineer, inventor and electrician
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