Analysis of a Coaxial Waveguide with Finite‐Length Impedance Loadings in the Inner and Outer Conductors

Feray Hacıvelioğlu,Alinur Büyükaksoy

doi:10.1155/2009/473616

Feray Hacıvelioğlu, Alinur Büyükaksoy

Open Access

https://doi.org/10.1155/2009/473616

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Abstract

A rigorous Wiener‐Hopf approach is used to investigate the band stop filter characteristics of a coaxial waveguide with finite‐length impedance loading. The representation of the solution to the boundary‐value problem in terms of Fourier integrals leads to two simultaneous modified Wiener‐Hopf equations whose formal solution is obtained by using the factorization and decomposition procedures. The solution involves 16 infinite sets of unknown coefficients satisfying 16 infinite systems of linear algebraic equations. These systems are solved numerically and some graphical results showing the influence of the spacing between the coaxial cylinders, the surface impedances, and the length of the impedance loadings on the reflection coefficient are presented.

Highlights

Coaxial discontinuity structures are widely used as an element of microwave devices, and in the permeability and permittivity measurement for materials 1–3
In order to observe the influence of the different parameters such as the surface impedances η1 and η2, the width l of the impedance loadings, and the distance b − a between the two coaxial cylinders on the reflection coefficient, some numerical results are presented
In order to obtain the explicit expressions of the reflection coefficient, the problem is first reduced into two coupled modified Wiener-Hopf equations and solved exactly in a formal sense by using the factorization and decomposition procedures

Summary

Introduction

Coaxial discontinuity structures are widely used as an element of microwave devices, and in the permeability and permittivity measurement for materials 1–3. In 8, 9 the scattering of a shielded surface wave in a coaxial waveguide by a wall impedance discontinuity in the inner cylinder has been analyzed. These classical results are related mostly with isolated discontinuities, and fail when there are several of them close enough to interfere with each other. The aim of the present work is to consider a new canonical scattering problem consisting of the propagation of the dominant TEM mode at the finite-length impedance discontinuities in the inner and outer conductors of a coaxial waveguide see Figure 1.

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Conclusion