Edwin Howard Armstrong - Early Work

Early Work

As an undergraduate, and later as a professor at Columbia University, Armstrong worked from his parent's attic in Yonkers, New York to develop the regenerative circuit, the superheterodyne receiver, and the superregenerative circuit. He studied under Professor Mihajlo Idvorski Pupin at the Hartley Laboratories, a separate research unit at Columbia University. Thirty-one years after graduating from Columbia he became Professor of Electrical Engineering, filling the vacancy left by the death of Professor J. H. Morecroft. He held the position until his death.

Armstrong contributed the most to modern electronics technology. His discoveries revolutionized electronic communications. Regeneration, or amplification via positive feedback is still in use to this day. Also, Armstrong discovered that Lee De Forest's Audion would go into oscillation when feedback was increased. Thus, the Audion could not only detect and amplify radio signals, it could transmit them as well.

While De Forest's addition of a third element to the Audion (the grid) and the subsequent move to modulated (voice) radio is not disputed, De Forest did not put his device to work. Armstrong's research and experimentation with the Audion moved radio reception beyond the crystal set and spark-gap transmitters. Radio signals could be amplified via regeneration to the point of human hearing without a headset. Armstrong later published a paper detailing how the Audion worked, something De Forest could not do. De Forest did not understand the workings of his Audion.

Armstrong's service as a signal officer in World War I led to his design of the superheterodyne circuit. The discovery and development of the technology made radio receivers, then the primary communications devices of the time, more sensitive and selective. Before heterodyning, radio signals often overrode and interfered with each other. Heterodyning also made radio receivers much easier to use, rendering obsolete the multitude of tuning controls on radio sets of the time. The superheterodyne technology is still used today. There was a dispute regarding who invented superheterodyne radio. Walter Schottky claimed that he had independently invented super heterodyne radio.