1887
Volume 22 Number 3
  • E-ISSN: 1365-2478

Abstract

A

The voltage induced in a horizontal loop on a layered ground has been calculated for the case where the loop is excited by a step current and measurements are made during the off‐cycle.

The expressions derived for a uniform ground show that for large time the induced voltage is approximately given by ≃— (αμ/20) (σμ2/)3/2 where σ is the conductivity of the ground, μ the permeability, the loop radius, and the amplitude of the current step. For small times the corresponding result is ≃—μ/2

When the ground is composed of a number of layers a numerical procedure for calculating the induced voltage is described.

The calculated responses of various multilayered structures show that at short times the induced voltage is asymptotic to that produced in the case of a uniform ground of conductivity equal to the top layer.

Interference effects in the top layer can lead to anomalous decay curves which may result in the underestimation of the conductivity of a buried layer.

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2006-04-27
2024-03-29
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