Integral Equation Technique for Finding the Current Distribution of Strip Antennas in a Gyrotropic Medium

Abstract

Much previous work on the characteristics of wire antennas in gyrotropic media such as a magnetoplasma, for example, either applies to electrically small antennas for which the current distribution along the antenna wire can be assumed given [Ko99], or employs the transmission line theory for determining the current distribution (see [Ad77] and [Oh86]).

In this study, the problem of finding the current distribution of strip antennas in a homogeneous gyrotropic medium is attacked using an integral equation method. Although our approach is applicable to a general gyrotropic medium, our primary attention will be paid to the case of a resonant gyroelectric medium in which the refractive index of one of the characteristic waves tends to infinity when the angle between the wave normal direction and the gyrotropic axis approaches a certain value determined by the medium parameters. In this case, the classical thin-antenna theory cannot be employed readily since no matter how small the cross section of the antenna wire might be physically, it is always possible to find some wave normal direction for which one wavelength in the medium will become less than the wire crosssectional extent and the antenna wire will appear to be “thick.” We do not consider the antenna problem in its full generality, but focus on two particular strip geometries for which the problem is mathematically tractable.