Ernst F. Alexanderson - Electrical Pioneer

Radio Development:

First Long Distance Voice Transmission:

Ernst Alexanderson made the power breakthrough that allowed Reginald Fessenden to transmit the human voice across a long distance in 1906.

Fessenden needed a continuous wave transmitter, a pure sine wave on a single frequency to make voice, he turned to General Electric as he knew they had some of the world's best engineers in the field at that time.

An assignment to build a high-frequency alternator for Professor Reginald A. Fessenden, one of the pioneer radio experimenters, gave Alexanderson an opportunity to prove himself. Fessenden contracted with General Electric to help design and produce a series of high-frequency alternator-transmitters. In 1903, Charles Proteus Steinmetz delivered a 10 kHz version which proved of limited use and could not be directly used as a radio transmitter. Fessenden's request for a faster, more powerful unit was assigned to Ernst F. W. Alexanderson

After two years of work, during which several models were constructed, Alexanderson delivered a practical alternator and it was installed in the Fessenden station at Brant Rock, Massachusetts. On Christmas Eve of 1906, it enabled this station to transmit the first broadcast of entertainment and music in history. Alexanderson improved this machine by substituting iron for wood in the armature. With more improvements in 1908 and 1911 this became the famous "Alexanderson Alternator". It assured reliable trans-Atlantic radio communication.

Later on Alexanderson thanked Fessenden for being a leader in radio. His persistence and vision inspired many like Alexanderson to stay working in the field. He called Fessenden the "American Father of radio".

More on the 1906 broadcast from IEEE >