Ground Return Parameters of Transmission Lines an Asymptotic Analysis for Very High Frequencies

Wave propagation with ground return is studied in the classical literature, by Carson andothers, for frequencies up to a critical upper limit, where displacement currents in the earth start becoming predominant. This paper derives simple expressions for the additional ground impedances, valid in the super-critical range. Problems when these are relevant are indicated. The new equations, when applied to thehigh frequency Carson range, show perfect coincidence with Carson´s equations. It appears that, at very high frequencies, the penetration depth remains finite, the earth resistance is also finite, while the earth reacrance becomes zero