VELOCITY TAPERING IN MICROWAVE AMPLIFIERS.
MICHIGAN UNIV ANN ARBOR ELECTRON PHYSICS LAB
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The low to moderate r-f conversion efficiencies characteristic of kinetic energy conversion devices may be enhanced by appropriately tapering the r-f circuit phase velocity. The nonlinear interaction equations have been solved in closed form for an HKB hard-kernel-bunch model to obtain an optimum taper form. Several velocity taper forms have been investigated in experimental amplifiers and the power output, gain, efficiency and phase shift characteristics of these amplifiers are discussed in detail. Conversion efficiencies up to 50 percent and near constant output power for a 20 db variation in r-f drive power have been realized in near optimally tapered circuit amplifiers. Further improvements realized include operation at a single voltage for maximum gain and power output and a nearly linear phase shift characteristic for a 10 percent voltage modulation. Author