Novel Propagation Model of Degenerate Band Edge Modes Using Dual Non-identical Pair of Coupled Transmission Lines

TL;DR

This paper introduces a new 'butterfly' structure using non-identical coupled transmission lines to generate higher-order dispersion modes, supporting a strong Degenerate Band Edge mode for enhanced RF wave-electron beam coupling.

Contribution

It proposes a novel propagation medium with a unique 'butterfly' structure that supports Degenerate Band Edge modes using coupled transmission lines inside a waveguide.

Findings

Supports strong TM01-like Degenerate Band Edge mode

Enhances coupling of electron beams to RF waves

Demonstrates slow wave characteristics of the structure

Abstract

We present a novel propagation medium using a pair of non-identical coupled transmission lines. The medium is referred to as `butterfly' structure and is composed of four coupled transmission lines. These four coupled transmission lines generate higher-order dispersion modes by coupling the modes supported on each of the transmission lines. When these transmission line pairs are placed inside a circular waveguide, they support a strong TM01-like Degenerate Band Edge mode. This property can be used to enhance coupling of the electron beams to RF waves for high-power Traveling Wave Tubes. In this paper, we present the slow wave characteristics and Degenerate Band Edge mode formation using the coupled pair of transmission lines.