Complete electric and magnetic field solutions of an overhead conductor above a lossy earth are derived in this letter, and “mode transition” from a low-frequency quasi-transverse electromagnetic (TEM) to a high-frequency transverse Magnetic (TM) mode has been investigated by means of axial electric field Ex . The calculated results of Ex show a clear correlation with the line attenuation constant during the mode transition. This characteristic is not observed in the axial electric field evaluated by the classical transmission line approach. The horizontal electric field Ey , vertical electric field Ez , and magnetic field H near to the conductor surface are nearly frequency-independent. As a result, the well-known analytical formulas assuming a perfectly conducting earth agree well with those calculated by the complete field solutions