An Efficient Model of High-Frequency Electromagnetic Field Coupling to Multiconductor Transmission Lines With the Presence of the Lossy Ground

The modeling of the high-frequency electromagnetic field coupling to multiconductor transmission lines (MTLs) is the essential subject for the protection of power lines. When the wavelength of the electromagnetic wave is smaller than the cross sections between MTLs, the response of MTLs cannot be evaluated by the classical transmission line approximation. Even though the full-wave method can deal with this problem, it is time consuming to evaluate the response of long MTLs. This article presents a theory and an efficient method to solve the problem of the high-frequency electromagnetic field coupling to MTLs with the presence of the lossy ground. The asymptotic method, adopted for its high computational efficiency, is extended to obtain the solutions of MTLs above the lossy ground. The problem is solved semianalytically using the proposed method, which is much more computationally efficient in dealing with long MTLs. Several numerical examples are presented to validate the accuracy and efficiency of the proposed method.