radar history

William Donzelli wdonzelli at gmail.com
Sun Mar 4 16:19:40 CST 2018

> Ordinary magnetrons had indeed been around for a while; they were invented in
> 1920. The British invention was the _cavity magnetron_, a quite different
> beast; it was kind of a cross between a magnetron and a klystron, with the
> best features of each.

The cavity magnetron was invented by a lot of people (Soviet,
Japanese, German, Swiss, United States, and I think the Danish*), just
like radar itself. Most of these inventors fell to the wayside,
because the cavity magnetron just was not a useful device. Most of
these inventors tried to use the cavity magnetron as a CW oscillator,
and in that mode, they are basically awful tubes. Randall and Boot
("the British") invented the pulse operation of the cavity magnetron -
a way to basically abuse the tubes but get pulses magnitudes more
powerful than previously done. This, of course, was the key to
microwave radar.

* much of this original research was not secret, just ignored. RCA's
"split anode tank magnetron" was even completely described in one of
their tech journals.


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