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The Magnetron and the Beginnings of the Microwave Age

JUL 01, 1985
A device of little promise, originally developed in 1916 as an alternative to grid control in vacuum tubes, became in 1940 the key to the successful development of radar by the Allied forces during the Second World War.
James E. Brittain

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.

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References

  1. 1. R. W. Clark, Tizard, MIT Press, Cambridge, Mass. (1965) p. 248;
    J. P. Baxter, Scientists Against Time, MIT Press, Cambridge, Mass. (1968) p. 136.

  2. 2. M. P. Fagan, ed., A History of Engineering and Science in the Bell System: The Early Years, 1875–1925, Bell Telephone (1975) p. 258.

  3. 3. J. E. Brittain, Adv. Electron. Electron Devices 50 (1980) p. 420.

  4. 4. A. W. Hull, Phys. Rev. 18, 31 (1921).https://doi.org/PHRVAO

  5. 5. A. W. Hull, J. Am. Inst. Elect. Eng. 40, 715 (1921).https://doi.org/JAIEAH

  6. 6. F. R. Elder, Proc. Inst. Radio Eng. 13, 159 (1925).

  7. 7. H. Yagi, Proc. Inst. Radio Eng. 16, 715 (1928).

  8. 8. C. G. Suits, H. E. Way, eds. The Collected Works of Irving Langmuir Vol. 4, Pergamon, New York (1960–62) p. 388.

  9. 9. See the magnetron bibliography in A. F. Harvey, High Frequency Thermionic Tubes, John Wiley, New York (1943).

  10. 10. C. W. Rice, Gen. Electr. Rev. 39, 363 (1936).https://doi.org/GEREAN

  11. 11. K. Posthumus, Wireless Eng. and Exp. Wireless 12, 126 (1935).

  12. 12. H. A. H. Boot, J. T. Randall, IEEE Trans. on Electron Devices 23, 724 (1976).https://doi.org/IETDAI

More about the authors

James E. Brittain, Georgia Institute of Technology.

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This Content Appeared In
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Volume 38, Number 7

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