Table of Contents
ISRN Optics
Volume 2012, Article ID 856748, 7 pages
http://dx.doi.org/10.5402/2012/856748
Review Article

Propagation of Electric Dipole Radiation through a Medium

1Department of Physics, Millersville University, P.O. Box 1002, Millersville, PA 17551, USA
2Department of Physics and Astronomy, Mississippi State University, P.O. Drawer 5167, Mississippi, MS 39762-5167, USA

Received 23 September 2012; Accepted 11 October 2012

Academic Editors: O. Frazão and V. Matejec

Copyright © 2012 Xin Li and Henk F. Arnoldus. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

When electromagnetic energy propagates through a material medium, the paths of energy flow may be altered, as compared to propagation in free space. We consider radiation emitted by an electric dipole, embedded in a medium with permittivity and permeability . For a linear dipole in free space, the field lines of energy flow are straight, but when the imaginary part of is finite, the field lines in the material become curves in the near field of the dipole. Therefore, the energy flow is redistributed due to the damping in the material. For a circular dipole in free space, the field lines of energy flow wind around the axis perpendicular to the plane of rotation of the dipole moment. When has an imaginary part, this flow pattern is altered drastically. Furthermore, when the real part of is negative, the direction of rotation of the flow lines reverses. In that case, the energy in the field rotates opposite to the direction of rotation of the dipole moment. It is indicated that in metamaterials with a negative index of refraction this may lead to an observable effect in the far field.