BW media-media with negative parameters, capable of supporting backward waves

Both isotropic and uniaxially anisotropic media capable of supporting backw ard waves are reviewed. Such an effect recently has been of great interest, and certain man-made composite media hate been introduced tinder the names "media with negative refraction factor" or "left-handed materials," effect ive in a certain band of microwaves. Neither of these names appears to be w ell founded, and "backward-wave medium" (or BW medium) is suggested instead . It is shown that, at an interface of a regular and a BW medium, Snell's l aw does not imply a negative refraction factor. However, the refraction is anomalous in the sense that the transmitted plane wave is a backward wave w ith a Poynting vector and a wave vector pointing in opposite lateral direct ions. The significance of the Zenneck wave and guided modes in a cylindrica l guide made of BW medium is discussed. Finally, the BW property is extende d to uniaxially, anisotropic media, and its occurrence is studied fbr diffe rent value combinations of its medium parameters. It is shown that a latera l backward wave can arise when a plane wave is transmitted through an inter face when one of the four parameters of the uniaxial medium is negative. (C ) 2001 John Wiley & Sons, Inc.