Ultrawideband Coalesced-Mode Operation for a Sheet-Beam Traveling-Wave Tube

• Published in: IEEE transactions on electron devices Vol. 63; no. 1; pp. 504 - 511
• Main Authors: Jianxun Wang, Guoxiang Shu, Guo Liu, Yang, L. Y., Yong Luo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Attenuation; Bandwidth; Building codes; Channels; Coalesced-mode operation; Dispersion; double staggered grating waveguide (DSGW); Impedance; Integrated circuit modeling; Mathematical analysis; Oscillators; Particle in cell technique; Radio frequency; sheet-beam traveling-wave tube (SB-TWT); Silicon; Simulation; Traveling wave tubes; Ultra wideband technology; Ultrawideband; User interface; Coalesced-mode operation; double staggered grating waveguide (DSGW); sheet-beam traveling-wave tube (SB-TWT); ultrawideband
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2015.2502620

Wider bandwidth property of traveling-wave tubes (TWTs) is continuously pursued to satisfy the increased data rates and multiple channels in modern communications. In this paper, the coalesced-mode operation instead of the general single-mode operation for the double staggered grating waveguide (DSGW) slow-wave structure (SWS) is proposed to achieve an ultrawideband property of the TWTs driven by sheet electron beam. Analytical results of the high-frequency properties for the SWS, including the dispersion characteristics, interaction impedance, and transmission property, demonstrate that the coalesced-mode operation for the DSGW is possible. A novel loading approach of the attenuator with good performance, and meanwhile, a compact configuration is proposed to suppress the potential oscillations, thus leading to a steady beam-wave interaction for the coalesced-mode operation. To verify the concept of coalesced-mode operation, particle-in-cell simulation is performed. Simulation results demonstrate that the optimized RF circuit indeed can steadily operate in coalesced mode and produce over 5-kW saturated output power (~10% efficiency) in a very broad frequency ranging from 37 to 52 GHz, corresponding to a relative bandwidth of 33.7%.