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De Forest vs. Armstrong: The Most Significant Patent War of the 20th Century

March 22, 2012

Lee De Forest (1873-1961) is considered to be one of the fathers of the electronic age. De Forest was a physicist who became an American inventor recognized for having registered over 180 patents. Through his revolutionary invention, the Audion, De Forest magnified weak electrical signals through the use of a vacuum tube. More specifically, he amplified radio waves through the development of a triode electron tube. The Audion became pivotal in the future of electronics and has been subsequently used to build telephones, TVs, and computers. De Forest first succeeded in amplifying radio waves in the confines of his laboratory in 1906.

Lee De Forest

Lee De Forest

The genius behind De Forest’s approach is that he used Guglielmo Marconi’s original invention of wireless telegraphy in order to formulate the concept of mass broadcasting. Marconi’s notion behind communication was limited as being between two positions while De Forest envisioned communication between one position and many others. January 12, 1910 marks the birth of public radio broadcasting when De Forest partially broadcast the opera Tosca and a live performance of tenor Enrico Caruso from the Metropolitan Opera House in New York City on the following day.

With the financial support of a Wall Street businessman, the De Forest Wireless Telegraph Company was formed supplying radio equipment to such clients as the U.S. War Department and the U.S. Navy. De Forest became a member of the Institute of Radio Engineers, and Devry University was originally named after him. De Forest was originally from Iowa and earned a Ph.D. from Yale University.



Edwin Howard Armstrong (1890-1954) was an American electrical engineer from New York City who invented frequency modulation (FM) radio. In this process, Armstrong made the discovery of De Forest’s Audion going into oscillation, or fluctuating in amplitude, when feedback was increased. Armstrong solved the problem of oscillation by increasing radio signals through regeneration and/or amplification via positive feedback. This helped eradicate static on the AM band brought upon by interference originating in the atmosphere and became the basis for transatlantic radio telegraphy. Eventually, the design of the Audion was simplified and solid transistors began replacing the oversized, in comparison, vacuum tube originally used. In a scientific tug of war, De Forest was able to produce an alternating current increasing the output of a transmitter by developing a feedback circuit. Consequently, Armstrong beat De Forest in applying for this patent.

Edwin Howard Armstrong

Edwin Howard Armstrong

Armstrong and De Forest engaged in what can be considered the most significant patent war of the twentieth century halting the communications revolution as associated with wireless transmission. Although both inventors made clear contributions resulting in modern day radio, the courts cited with De Forest. Unfortunately, Armstrong committed suicide in 1954 as a result.

Image/Photo Credits: Wikipedia/Wikimedia Commons.


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