Modeling of Practical Multi-Octave-Band Helical Slow-Wave Structures of a Traveling-Wave Tube for Interaction Impedance

Abstract

Theoretical model is developed for evaluating the interaction impedance of practical helical slow-wave structures which are anisotropically and/or inhomogeneously loaded specially for multi-octave bandwidths. The discrete supports have been azimuthally smoothed out into a number of dielectric tubes of different permittivity values, while the metal vanes have been modeled by an axially conducting cylinder suitably located in the structure. Theoretical results agree closely with published experimental results over a wide range of frequencies. © 1992 IEEE