Traveling-Wave Amplification by Means of Coupled Transmission Lines

The theory of interaction between coupled transmission lines moving relative to each other is developed, and conditions yielding waves increasing exponentially with distance (amplification) are found. The case of lossless lines, one moving and one stationary, is analyzed in considerable detail, and the results are shown to be applicable to the helix traveling-wave tube. The theory also suggests the possibility of traveling-wave amplification in systems other than electrical, and a mechanical traveling-wave oscillator has been built.