A Novel Serpentine Waveguide Circuit Topology With Changeable Narrow Side and Nonconcentric Circular Bends

• Published in: IEEE transactions on plasma science Vol. 51; no. 10; pp. 3265 - 3272
• Main Authors: Li, Fei, Xiao, Liu, Zhao, Jiandong, Wang, Zicheng, Yi, Hongxia, Shang, Xinwen, Li, Yanwei, Sun, Yuhui, Gao, Cha
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-10-2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bends; Circuits; Computer simulation; Couplings; DH-HEMTs; Dispersion; Efficiency; Electronic efficiency; Electrons; first stopband; Frequency ranges; Impedance; Millimeter waves; novel serpentine waveguide circuit topology (NSWC); on-axis coupling impedance; Oscillators; Power generation; saturated output power; Simulation; Simulation analysis; Software packages; Terahertz frequencies; Topology; Traveling wave tubes; Traveling waves; Waveguides
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2023.3311255

Higher power, higher efficiency, and better stability are very urgent for the sub-millimeter wave and terahertz traveling-wave tube (TWT). A novel serpentine waveguide circuit structure with changeable narrow side and nonconcentric circular bends [novel serpentine waveguide circuit topology (NSWC)] is proposed to meet above demands in this article. Based on the simulation analysis results of electromagnetic analysis software High Frequency Structure Simulator(HFSS), the NSWC owns higher on-axis coupling impedance, which is crucial for high power and efficiency, and wider stopband gap near the <inline-formula> <tex-math notation="LaTeX">{2}\pi </tex-math></inline-formula> eigenmode that means improved stability than other three commonly used structures: traditional serpentine waveguide slow wave structure (TS-SWS), hybrid-serpentine slow wave structures (HS-SWSs), and folded waveguide slow wave structure with modified circular bends (MCB-SWS). In order to validate this novel topology, Microwave-Tube Simulator Suite (MTSS) software package and Computer Simulation Technology Particle Studio (CST-PS) are applied to design and analyze two types of <inline-formula> <tex-math notation="LaTeX">{E} </tex-math></inline-formula>-band TWTs: TWT-I with MCB-SWS and TWT-II with the NSWC. The simulated results show that the stable output powers and electronic efficiencies for TWT-II are more than 148.48 W and 10.01% in the frequency range of 81-86 GHz, respectively, which are more than 32.7% and 28.3% higher than those for TWT-I in the same frequency range, which confirm that the NSWC is a promising slow wave circuit with raised output power, increased electronic efficiency and improved stability in millimeter wave and terahertz frequency bands.