The Cavity Magnetron: Not Just a British Invention [Historical Corner]

It is a common belief by many people that the resonant-cavity magnetron was invented in February 1940 by Randall and Boot from Birmingham University. In reality, this is not the full story. Rather, it is a point of view mostly advocated by the winners of the Second World War, who gained a great benefit from this microwave power tube (thanks to a two-orders-of-magnitude increase of power) in the Battle of the Atlantic, in night bombing until the final collapse of the German Reich, and in many other operations. This paper discusses the contributions by other nations, mainly France, but also Germany, Japan, The Netherlands, the Czech Republic, the USSR, and even more, to the cavity magnetron and to its roots.