A New System of Frequency Modulation

The development of a new phase-modulator tube is described. In a concentric structure of conventional dimensions, a radial electron stream is shaped into a wave-like pattern which progresses continuously around the cathode. Phase shift, 12 to 16 times larger than in conventional modulators, is produced by electro-magnetic deflection. The failings of early models are analyzed and the steps are reviewed which resulted in the development of a satisfactory tube structure.