Differential mode for four-conductor nonuniform transmission line with grounded wire at high frequency

This work presents the numerical characterization of the balanced differential mode for an overhead four-conductor nonuniform transmission line above lossy earth with grounded wire at high frequency over the 1-30MHz ranges. The nonuniform multiconductor transmission line can be subdivided into sections of uniform MTL to compute the elementary ABCD matrices. This technique is used to calculate the transmitted power efficiency when the overhead wires have sag with ground wire. A comparison between uniform and nonuniform MTL is made to quantify the effect of the sag in the balanced differential mode. It appears that the effect of the sag is negligible for the power efficiency of the four-conductor transmission line working in balanced differential mode over a large frequency range. In this case, the ideal available span for PLC reaches 5000m.