Traveling-Wave Tubes

Very-broad-band amplification can be achieved by use of a traveling-wave type of circuit rather than the resonant circuit commonly employed in amplifiers. An amplifier has been built in which an electron beam traveling with about 1/13 the speed of light is shot through a helical transmission line with about the same velocity of propagation. Amplification was obtained over a bandwidth 800 megacycles between 3-decibel points. The gain was 23 decibels at a center-band frequency of 3600 megacycles.