The Physics of the Ground Loop

A ground loop is often used both as a model to explain the basics of electromagnetic exploration and as a tool in the calibration of AEM systems. A thorough understanding of the underlying physics is essential. During the calibration procedure of an AEM system, the electrical current in the ground loop was measured and recorded. A mathematical model in the form of a differential equation was stated for the current in the ground loop. The solution of the differential equation was calculated allowing for the particular transmitter current wave shape. There is good qualitative conformity between the measured current and modelled current. Quantitative agreement of the current amplitude depends on an accurate knowledge of the geometries of the problem.