Internal Impedance of Two-Layer Cylindrical Conductors

Abstract

Computation of the internal impedance per unit length of solid and tubular cylindrical conductors, energized by time-harmonic current, needs to take into account the skin effect. Computation algorithm involves direct numerical manipulations with Bessel functions. These functions are defined by infinite series, which yield unstable and often erroneous results, particularly for large magnitudes of the function argument at high frequencies. Therefore, different approximate formulas are used in order to alleviate this problem. In this paper, exact formulas, with scaled Bessel and Neumann functions and scaled coefficients, for internal impedance of two-layer cylindrical conductors are presented. In two numerical examples presented, results for internal impedances per unit length of two-layer conductors computed by exact formulas are compared with results based on Amos subroutines, which are used in program package MATLAB
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