On electromagnetic radiation in nonlocal environments—Steps toward a theory of near field engineering

We study the antenna radiation field when the surrounding medium is spatially responsive. The Green´s function of such nonlocal or spatially dispersive media is derived and a spectral expansion is obtained. It is shown that the antenna can launch both backward and forward wave modes into the far zone, and that this occurs also in a natural way in the near zone. We also demonstrate that the medium can localize the field around the antenna, giving rise to a wide range of potentials for future near field engineering.