Controlling Electromagnetic Scattering of a Cylindrical Obstacle Using Concentric Array of Current Sources

Abstract

In this article, a novel method is proposed to control the electromagnetic scattering due to an infinitely long cylinder, which is based on the concept of the concentric circular array. The method has its roots in the surface equivalence principle, according to which the scattering due to an object can alternatively be represented by putting induced current sources (electric or magnetic) on its surface and then assumed to radiate in an open medium (physical equivalent) or in the presence of the cylinder (induction equivalence). Using this, a cylindrical object is approximated by a circular array obtained by discretizing the induced current. The scattered field is then represented as field radiated by the circular array. Using this representation, it is now possible to tailor the scattering pattern of a cylinder by placing another circular array concentric to the original cylindrical object and controlling its excitation magnitude and phases. In this way, the proposed method also leads to a generalization of the active cloaking concept, in which the excitation amplitude of concentric circular array is negative of that induced on the original cylindrical obstacle’s surface. The method is applied both for plane wave and line-source scattering of infinitely long conducting as well as dielectric cylinders and verified by COMSOL simulations.