Using Pole-Dipole Array for Measurements of Frequency Dependent Soil Electrical Properties

For a grounding design, the frequency dependent soil parameters should be taken into account, as these parameters appreciably influence transient grounding characteristics. However, additional experimental data are needed for the exploration of this phenomenon in a more general way. In order to perform a large number of measurements of the frequency dependent soil electrical properties, an appropriate measurement method is needed. However, measurement results can be significantly influenced by the electromagnetic coupling between circuits. Thus, the error due to the electromagnetic coupling should be minimized. During measurements, many different factors can influence the results apart from the electromagnetic coupling. Therefore, examining this error by the calculation method is more convenient. In the article, a formula for depth investigation characteristic is derived for the pole-dipole electrode array with the arbitrary location of the measurement electrodes. Then, calculations with the pole-dipole array are performed to examine the error caused by the electromagnetic coupling between measurement circuits. Calculation results are analyzed, and recommendations for the measurements are given.