Computation of Current Distribution of Cylindrical Antennas and Scatterers in Multi-Layer Media Using a Multi-Wire Model

Abstract

ABSTRACT In this paper, a new multi-wire model is developed to solve the important problem of the determination of the longitudinal current distribution along and around a wire antenna protruding through multi-layer medium. This problem is important because the longitudinal directed current distribution on a wire antenna near the interface between two layered medium is not uniform as a function of the angle around the antenna because of proximity effects and because the longitudinal current distribution along the antenna can vary significantly when the antenna passes through layers having different electrical properties. In the past, almost all numerical methods have treated this wire antenna problem by assuming a longitudinal current that was uniform in the azimuthal direction around the antenna. With the new model, the magnitude of the longitudinal current azimuthal around the wire antenna can be modeled in terms of many small thin wires in a cylindrical cage-like configuration. A moment method procedure based on this model and the mixed potential integral equation (MPIE) has also been developed for analysis of this problem which is fast and convenient as compared to standard formulations. The validity and convergence of the new model are verified by comparing with experimental and other numerical results. Several different cases are analyzed using the cage model presented in this paper for verification of the model. The results presented in this paper can also be considered as bench mark problems that can be used for verifications of other numerical techniques.