The Magnetron and the Beginnings of the Microwave Age

In the autumn of 1940, a British technical and scientific mission, headed by Sir Henry Tizard, brought to the United States a famous black tin trunk containing, among other things, an electronic device that exerted a profound influence on the outcome of the war. This device, the cavity magnetron, was developed by two British physicists, Henry A. Boot and John T. Randall, and was built at the British General Electric Laboratory at Wembley. The British at first hesitated to divulge the design of the magnetron to Americans for fear that it would fall into the hands of German intelligence, but the subsequent developments completely justified the Tizard commission's actions. The disclosure of this device led to the formation later that year of the Radiation Laboratory at Massachusetts Institute of Technology. An elite group of scientists and engineers recruited from universities and industry developed there a variety of magnetrons during the war years and incorporated them into more than 100 radar systems, giving the Allied forces a decisive technical lead. More than two billion dollars was invested in the development and production of radar systems by the United States during the war, and a momentum in microwave technology was created that persisted in the postwar period.