Asian Journal of Physics Vol 32, Nos 9 – 12 (2023) 607-613

Analysis and characterization of an octave-bandwidth twin-folded-waveguide slow-wave structure

M Sumathy and Subrata Kumar Datta
Microwave Tube R&D Centre , DRDO, Ministry of Defence, Jalahalli, Bangalore – 560 013, India
Dedicated to Prof B N Basu

A novel configuration of folded-waveguide slow-wave structure was conceptualized in which a pair of identical conventional folded-waveguide slow-wave structures is combined in a contra-twined placement (similar to a contra-wound helix or a ring-bar structure). The proposed structure promises cold-bandwidth close to an octave with lowered interaction impedance. The twin-folded configuration would ease out the manufacturing aspects appreciably and also would allow operation with a larger electron beam carrying higher current or requiring lower focusing magnetic field. The reason being a constituent conventional single folded-waveguide structure operating at a low frequency (having larger dimensions), in its twin-folded configuration, would offer operability approximately at double the frequency over almost an octave bandwidth. The analysis of the structure was carried out by parametric approach and validated against numerical simulation and cold-test measurement, for a structure operating at Ka-band and validated against numerical simulation at W-band. © Anita Publications. All rights reserved.
Keywords: Broadbanding, Folded-waveguide slow-wave structure, Twin-folded-waveguide slow-wave structure.

Peer Review Information
Method: Single- anonymous; Screened for Plagiarism? Yes
Buy this Article in Print © Anita Publications. All rights reserve


  1. Hutter R G E, Beam and Wave Electronics in Microwave tubes, (New York: Van Nostrand), 1960.
  2. Na Y H, Chung S W, Choi J J, Analysis of a broadband Q-band folded-waveguide traveling-wave tube, IEEE Trans Plasma Sci, 30(2002)1017–1023.
  3. Han S T, Kim J, Park G S, Design of folded waveguide traveling-wave tube, Microw Opt Technol Lett, 38(2003) 161–165.
  4. Booske J H, Converse M C, Kory C L, Chevalier C T, Gallagher D A, Kreischer K E, Heinen V O,  Bhattacharjee S, Accurate parametric modeling of folded waveguide circuits for millimeter-wave traveling wave tubes, IEEE Trans Electron Devices, 52(2005)685–694.
  5. Sumathy M, Vinoy K J, Datta S K, Analysis of ridge-loaded folded-waveguide slow-wave structure for broad band traveling-wave tubes, IEEE Trans Electron Devices, 37(2010)345–349.
  6. Zhang C, Gong Y, Gong H, Wei Y, Wang W, Investigation of the dielectric-loaded folded waveguide traveling-wave tube amplifier, J Infrared Millim Terahertz Waves, 30(2009)1027–1037.
  7. Indian Patent: Twin-Folded-Waveguide Slow-Wave Structure for Traveling-Wave Tube, Patent No. 322394
  8. Computer Simulation Technique (CST), GmbH. Online:
  9. Sumathy M, Vinoy K J, Datta S K, Non resonanat perturbation formula for measurement of interaction impedance of folded-waveguide slow-wave stucture, Proc IEEE International Vacuum Electronics Conference, 2010, p 98.