Design and Experimental Study of a Widebandwidth W-Band Folded Waveguide Continuous-Wave TWT

Design and development of a high power, wide-bandwidth W-band travelling wave tube (TWT) is presented in this paper. The design and simulation covers folded waveguide (FWG) circuit, electron gun, periodical permanent magnet system, and coupling window with the emphasis on the FWG optimization and particle-in-cell simulation by Computer Simulation Technology (CST) particle studio. Two TWT prototypes have been developed and tested, which demonstrate over 30-W output power in frequency between 91 and 101 GHz with over 30-dB saturated gain. Maximum power was found to be about 40 W around 95 GHz, while the flat output power curve under same drive level was observed.