Study on Staggered U-Shaped Groove Sine Waveguide for G-Band TWT

To improve the performance of efficiency bandwidth product (EBP) and power capacity for G-band continuous-wave traveling-wave tube (CW TWT), a novel staggered U-shaped groove sine waveguide slow-wave structure (SUGSWG SWS) is proposed in this article. The theoretical analysis of high-frequency and beam-wave interaction characteristics indicates that the SUGSWG TWT has low insertion/reflection loss, broadband (3-dB power bandwidth of over 19 GHz), and high maximum output power (over 66 W), of which the EBP could reach whopping 103%·GHz (about three times the state of art). In the merit of its special geometry, the power capacity of this novel SWS is also about 1.6 times its existing peers. A prototype of a two-section SUGSWG TWT is designed, fabricated, and experimented for verifications. The hot test demonstrated that the peak power of 56 W, the 3-dB power bandwidth of 16 GHz, and the EBP of 75.4%·GHz were achieved, with the transmission rate practically tuned around 93%. Those measurement results are consistent with the theoretical predictions under the same transmission conditions. Those studies validate the remarkable potential of our proposed novel slow wave structure (SWS) in TWTs for THz applications.