Time-domain treatment of multi-layer soil in transient analysis of aerial multi-conductor transmission lines

Based on the complex ground return plane method and Maxwell´s equations, the ground return impedance of aerial multi-conductor transmission lines (MTLs) above multi-layer soil is researched in frequency domain, and its time-domain expression is obtained by using the vector fitting method and inverse Laplace transform. After the validity of the method above is tested, the effect of the multi-layer soil is included in the FDTD method based on recursive convolution in order to research the wave process of aerial MTLs. The method proposed is demonstrated to give the same results as the famous software EMTP, and to have a little difference from the results of method of moment (MoM). Finally, two examples are analyzed