Studies on broadband output circuit of high power klystron

Three types of broadband output circuit, including filter-loaded output circuit, double gap coupling cavity operating in overlapping mode, and filter loaded double gap coupling cavity, have been studied and applied to a practical broadband klystron. The microwave equivalent circuit for calculating impedance-frequency characteristics and the design method for determining circuit parameters are descibed in this paper. S-band klystrons with a filter-loaded circuit have a bandwidth of 7.5% at a power level of 1 MW. S- and L-band klystrons with overlapping mode double gap coupling cavity have a bandwidth of 7.5~10% at a power level of 700 kW to 1 MW. S- and L-band multi-beam klystrons have a bandwidth of 7~11% at a power level of 200 kW