Modeling of the Mode Conversion Effect Induced by Asymmetry/Coating in Floating Multiconductor Cables

This article discovers a special mode conversion effect induced by dielectric coatings and asymmetric structures in floating multiconductor cables illuminated by a plane wave. Accordingly, a semianalytical model is proposed to predict the terminal response induced by this mode conversion effect. To this end, the modes on cables are decomposed into the common-mode (CM) and differential-mode (DM) components. First, the floating multiconductor cables are considered equivalent to a CM single conductor, and the current distribution along this conductor is obtained through full-wave simulations. Second, the transfer inductance matrix, which characterizes the conversion between the CM currents and DM equivalent induced sources, is derived, after which the transmission line model for the DM is constructed. Then, two application examples involving floating three- and four-conductor cables excited by a plane wave are examined to validate the performance. Furthermore, the effect of the dielectric coating thickness on the asymmetry/coating-induced mode conversion effect (ACIMCE) is analyzed by the Monte Carlo method, a regular polygon cross-sectional design method is proposed to eliminate the ACIMCE, and a low-frequency model is provided to understand the CM coupling mechanism. Notably, the existence of ACIMCE and the practical application of its elimination method to actual cables need further experimental validation.