The electrically short sheathed dipole: Experimental relationship between its measured admittance and the permittivity of the external medium

Motivated by a study of the electrical properties of deep polar ice, a technique was developed to interpret the measured admittance of an electrically short sheathed dipole probe in terms of the complex relative permittivity of the surrounding material. With the related analytical problem unsolved, the experimental study described herein provides new information for evaluating theoretical models as well as guidelines for the full-scale design of systems to measure the properties of ice or other materials in similar circumstances, and bounds on the measured sample volume. Reduction of the admittance data is accomplished with the aid of a three-element equivalent circuit resulting from a laboratory model study that is also described. Potential applications include measure-merit of the in situ properties of rock and naturally occurring ice masses surrounding deep drill holes. Preliminary results from the Antarctic ice sheet at Byrd Station are included by way of illustration.