Time Reversal in Subwavelength-Scaled Resonant Media: Beating the Diffraction Limit
Figure 4
(a) The experimentally and numerically studied resonant wire array. The 20 * 20 wires are 1.2 cm periodically spaced on a square grid and are 3 mm in diameter and 40 cm long. Superimposed are mapped the electric field of 4 Bloch modes out of the 400 that are supported by the structure. (b) Shape of the TEM field inside the structure. The transverse magnetic (electric) field is maximum (null) in the middle of the medium of the structure and null (maximum) at the interfaces with air. Only an electric evanescent component exists outside of the medium in the direction. (c) Dispersion relation linking the transverse wavevectors (normalized to π/a) of the modes to their resonant frequencies (normalized to the resonant frequency of a single wire ). The solid curve is analytical (equation (5)), while the symbols represent various modes obtained numerically. This curve shows that the Bloch modes which are evanescent in the direction (the curve is under the light line) show a dispersive behaviour.
