Backward Wave Oscillator

Can anyone forward me some useful link or materialsregarding BWO(Backward Wave Oscillator), specially its application in space eletronics.(Space communication circuits).

Best regards,

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BWO was a powerful vacuum tube technology to produce far millimeters generators. The output power was strong enough to drive mixers (tens of mW), also it was possible to phase lock. I don't know why they are dead.

Up to few years ago, an US company was selling a Russian/Chinese made BWO's.
look at Dorado International http://www.dorado-intl.com/index.shtml

Now a russian company sell BWO: http://www.elva-1.com