A coupled resonator reflex klystron

The theory of a coupled resonator reflex klystron is developed and its reduction to practice described. This tube differs from the conventional reflex klystron in that its performance characteristic is derived from the interaction between the electronic admittance due to a bunched electron stream and the input admittance of two synchronously tuned, coupled resonators. As a result: (1) power output can be made to be substantially flat over the greater part of the electronic tuning range; (2) the half-power electronic tuning range of the coupled resonator reflex klystron is more than twice that of a klystron using the same electron optical system but interacting with a single resonator; and (3) modulation linearity may be obtained over a greatly increased frequency swing. A reduction in power output of about 3db occurs for a secondary resonator Q and coupling coefficient adjustment designed to yield a maximum flat band or maximum electronic tuning while a much smaller reduction in output power will provide a substantial improvement in modulation linearity.