Definition and computation of cylindrical conductor internal impedance for large parameters

Exact formulas for internal impedance per unit length of solid and tubular cylindrical conductors energized by time-harmonic current involve Bessel functions. These functions are defined by infinite series, which yield unstable and often erroneous results for large magnitudes of the complex function arguments. For such cases, approximate formulas can be used. Results obtained by exact formula and approximate formulas for computation of internal impedance per unit length of solid and tubular cylindrical conductors are compared.