Modelling of finite size vane-loaded helical slow-wave structures

Author

Zhang, Y. ; Mo, Y.L. ; Li, J.Q. ; Zhou, X.L.

Author_Institution

Inst. of High Energy Electron., Univ. of Electron. Sci. & Technol. of China, Chengdu Sichuan, China

Volume

151

Issue

2

fYear

2004

fDate

4/1/2004 12:00:00 AM

Firstpage

135

Lastpage

142

Abstract

The vane-loaded helical slow-wave structure is widely used in high power, broadband travelling wave tubes (TWTs). Taking the radial thickness of the helix into account, the finite size vane model is suggested for vane-loaded helical slow-wave structures (SWS). The expressions of the dispersion equations, interaction impedance and attenuation constant of this model are derived. Two vane-loaded helical slow-wave structures of the travelling wave tube (TWT) are calculated by the derived equations. The calculated results are compared with the results of measurement and the calculated results of the infinite number of vanes model (INV) that also considered the radial thickness of the helix. The influence on dispersion characteristics is analysed for the thickness of the helix and different centre angles of the vanes. It is interesting to find that the centre angle (2θ) of the vanes has a fixed value when the phase velocity is a minimum.

Keywords

dispersion (wave); slow wave structures; TWT; attenuation constant; broadband travelling wave tube; dispersion characteristic; finite size helical slow-wave structure; finite size vane model; helix radial thickness; interaction impedance; phase velocity; vane centre angle; vane model infinite number;

fLanguage

English

Journal_Title

Microwaves, Antennas and Propagation, IEE Proceedings

Publisher

iet

ISSN

1350-2417

Type

jour

DOI

10.1049/ip-map:20040165

Filename

1275417