High-Efficiency W-Band Pulsed TWT With Three-Stage Depressed Collector

This letter presents the design and experimental study of a W-band traveling wave tube (TWT) with an overall efficiency of over 40% using multistage depressed collectors (MDCs). The folded waveguide (FWG) with a high coupling impedance and phase velocity tapering (PVT) circuit has been used to achieve the electronic efficiency of over 10%. Furthermore, a three-stage depressed collector with a high recovery efficiency was designed to enhance the overall efficiency in W-band pulsed TWTs. A prototype tube was then fabricated and tested with a beam current of 193 mA and a beam voltage of 20.8 kV. The testing data shows that the overall efficiency of 40.6% was obtained at over 410 W output power within 5 GHz at 20% duty cycle, with the maximum efficiency of 47%. That is the highest efficiency test results of W-band TWTs reported so far.