Determination of the Mean Values of Conductivity and Dielectric Constant from the Field Structure of a Magnetic Dipole

摘要

The equations for a magnetic dipole in a homogeneous, conductive medium are analyzed. The field is shown to be elliptically polarized in the transition zone between near field and far field. Quantities are introduced which are easy to determine by experiment: from them, the complex propagation constant can be determined at a given distance. Thus, conductivity and dielectric constant can be calculated for a given frequency. The applicability of this method is confined to the region of validity of the basic expressions. This comprises the condition that the cavity which contains transmitter and receiver is small as compared to the wave-length in matter. Measurements at 120 kc/sec satisfied this condition. The principle of measurement and its evaluation are described. The results are compared with results obtained from natural rock samples. (Author)