Optimization design of high efficiency in 140GHz folded waveguide slow wave structure

The paper puts forward a design thought of phase velocity tapering in the design of 140GHz folded waveguide traveling wave tubes. It can make electron with traveling wave field synchronization again in output segment of interaction circuit. By the phase velocity analysis and optimized design, the big signal simulation is calculated in operating voltage 14.05kV and current 25mA. The efficiency is improved 12% in 140GHz, output power in improved 1.4W. The efficiency is improved 42% in 142GHz, output power is improved 2.5W. -1dB bandwidth is improved 7GHz from 5GHz. The design improves the bandwidth and work efficiency in D band folded waveguide traveling wave tubes.