ELECTROMAGNETIC FIELDS OF A SMALL LOOP ANTENNA ON THE SURFACE OF A POLARIZABLE MEDIUM

Abstract

Studies are made in this paper on the characteristics of the electromagnetic fields produced by a small loop antenna placed on the surface of a medium which exhibits induced‐polarization effects. An approximate expression for the effective impedance of a polarizable medium is used for this purpose. Both the real and imaginary parts of the impedance are appreciably frequency‐dependent. Different expressions suitable for specific ranges of time and specific values of the characteristic parameter of the medium are obtained for the fields when the antenna is excited by a step‐function current source. The step‐function responses show marked differences in characteristics as the parameter of the medium is increased from very small values, typical of membrane polarization, to very large values corresponding to electrode polarization. The rate at which the magnitude of the transients decays with time is highly dependent on this parameter. The rate of decay in the initial small part of the transient curve increases, whereas in the remaining major part the rate decreases with rise in the value of the parameter.