February 21, 1940

Audio of this article is brought to you by the Air & Space Forces Association, honoring and supporting our Airmen, Guardians, and their families. Find out more at afa.org

Henry A.H. Boot and John T. Randall, working at the University of Birmingham, England, create the first practical magnetron. The magnetron, a resonant-cavity microwave generator, is vital in the development of airborne radar.

Audio of this article is brought to you by the Air & Space Forces Association, honoring and supporting our Airmen, Guardians, and their families. Find out more at afa.org