中国物理B ›› 2006, Vol. 15 ›› Issue (11): 2661-2668.doi: 10.1088/1009-1963/15/11/034

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Study of the double rectangular waveguide grating slow-wave structure

路志刚, 宫玉彬, 魏彦玉, 王文祥   

  1. School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
  • 收稿日期:2006-02-20 修回日期:2006-06-06 出版日期:2006-11-20 发布日期:2006-11-20
  • 基金资助:
    Project supported by the State Key Program of National Natural Science of China (Grant No 60532010).

Study of the double rectangular waveguide grating slow-wave structure

Lu Zhi-Gang(路志刚)†, Gong Yu-Bin(宫玉彬), Wei Yan-Yu(魏彦玉), and Wang Wen-Xiang(王文祥)   

  1. School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
  • Received:2006-02-20 Revised:2006-06-06 Online:2006-11-20 Published:2006-11-20
  • Supported by:
    Project supported by the State Key Program of National Natural Science of China (Grant No 60532010).

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摘要： A slow-wave structure (SWS) with two opposite gratings inside a rectangular waveguide is presented and analysed. As an all-metal slow-wave circuit, this structure is especially suited for use in millimetre-wave travelling wave tubes (TWTs) due to its advantages of large size, high manufacturing precision and good heat dissipation. The first part of this paper concerns the wave properties of this structure in vacuum. The influence of the geometrical dimensions on dispersion characteristics and coupling impedance is investigated. The theoretical results show that this structure has a very strong dispersion and the coupling impedance for the fundamental wave is several tens of ohms, but the coupling impedance for --1 space harmonic wave is much lower than that for the fundamental wave, so the risk of backward wave oscillation is reduced. Besides these, the CST microwave studio is also used to simulate the dispersion property of the SWS. The simulation results from CST and the theoretical results agree well with each other, which supports the theory. In the second part, a small-signal analysis of a double rectangular waveguide grating TWT is presented. The typical small-signal gain per period is about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4\%.

关键词: TWT, rectangular waveguide grating, dispersion, small signal gain

Abstract: A slow-wave structure (SWS) with two opposite gratings inside a rectangular waveguide is presented and analysed. As an all-metal slow-wave circuit, this structure is especially suited for use in millimetre-wave travelling wave tubes (TWTs) due to its advantages of large size, high manufacturing precision and good heat dissipation. The first part of this paper concerns the wave properties of this structure in vacuum. The influence of the geometrical dimensions on dispersion characteristics and coupling impedance is investigated. The theoretical results show that this structure has a very strong dispersion and the coupling impedance for the fundamental wave is several tens of ohms, but the coupling impedance for --1 space harmonic wave is much lower than that for the fundamental wave, so the risk of backward wave oscillation is reduced. Besides these, the CST microwave studio is also used to simulate the dispersion property of the SWS. The simulation results from CST and the theoretical results agree well with each other, which supports the theory. In the second part, a small-signal analysis of a double rectangular waveguide grating TWT is presented. The typical small-signal gain per period is about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4%.

Key words: TWT, rectangular waveguide grating, dispersion, small signal gain

中图分类号:  (Waveguides, transmission lines, striplines)

  • 84.40.Az
41.20.Jb (Electromagnetic wave propagation; radiowave propagation) 84.40.Fe (Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.))