Evaluation of the frequency dependence of the complex conductivity of a resistive chamber by comparing theoretical and measured S-matrices. (28th December 2018)

• Record Type: Journal Article
• Authors: Shobuda, Yoshihiro
• Is Part Of: Progress of theoretical and experimental physics. Volume 2018:Number 12(2018)
• Publication Date: 2018-12-28
• Subjects: G12; Physics -- Periodicals; Mathematical physics -- Periodicals; 530.05
• DOI: 10.1093/ptep/pty124
• Languages: English
• ISSNs: 2050-3911

Abstract

Abstract: For an accurate calculation of the resistive-wall impedance of a resistive chamber, we must know the conductivity of the resistive material. The conductivity of the material at a given frequency can be evaluated by measuring the $S$ -matrix of a propagation mode in a waveguide. However, in most cases, only the absolute value of the $S$ -matrix is used for evaluation under the assumption that the conductivity is pure real, although both the $S$ -matrix and the conductivity are complex numbers in general. To evaluate complex conductivity from a measured complex $S$ -matrix, we derive new theoretical formulae for the $S$ -matrix for the TE$_{11}$ and TM$_{01}$ modes of a waveguide and for the quasi-TEM$_{00}$ (quasi-transverse electromagnetic) mode of a coaxial waveguide, where complex conductivity is assumed. In a reverse way, we can determine the conductivity of a material by using it as a fitting parameter in a comparison of a measured $S$ -matrix with those obtained using theoretical formulae. The three independent methods facilitate triple-checking of the accuracy of the measured conductivity.