Circuit design of a three-cavity W-band extended interaction klystron

A compact three-cavity circuit with ladder type structure is designed for the pencil beam W-band extended interaction klystron (EIK). Circuit parameters such as coupling coefficient M, characteristic impedance R/Q and beam-loading conductance Ge are analyzed and optimized in the design procedure. The initial beam parameters are 18.1 kV, 0.2 A and 0.5 mm in diameter. Simulation predicts a saturation output power of 300 W is achieved at 94.5 GHz with an input power of 290 mW, corresponding to the gain of 30 dB and electronic efficiency of 8.3%.