Field-to-Wire Coupling Model for Arbitrarily Routed Shielded Cables Above Ground

In this article, transmission line (TL) theory is applied to the modeling of shielded cables with arbitrary routing paths above ground, enabling efficient and accurate prediction of field-to-wire coupling effects. The external electromagnetic field is first modeled either analytically (such as via plane wave illumination) or numerically (such as through nonuniform complex fields), and the cable path is discretized for field sampling along its trajectory. Afterward, a segmented TL-based external-loop circuit model is established, and the current distribution in the external loop is obtained through a recursive chain parameter algorithm. With an appropriate transfer impedance model, a segmented TL-based internal-loop circuit is subsequently formulated to determine the induced terminal currents. The accuracy and efficiency of the proposed model are verified through three representative full-wave simulation cases involving tubular-shield coaxial and multiconductor cables with both straight and arbitrarily routed (Gaussian-modulated helical) paths, including dielectric-coated, lossy, and segmentwise nonuniform shielding configurations, driven by analytical plane wave and numerically simulated fields. Furthermore, the proposed method was validated through radiated susceptibility experiments in a gigahertz transverse electromagnetic cell using three braided-shield coaxial cables arranged along straight and parabolic paths.