  It is shown that a system of two coupled planar material sheets possessing
surface mode (polariton) resonances can be used for the purpose of evanescent
field restoration and, thus, for the sub-wavelength near-field imaging. The
sheets are placed in free space so that they are parallel and separated by a
certain distance. Due to interaction of the resonating surface modes
(polaritons) of the sheets an exponential growth in the amplitude of an
evanescent plane wave coming through the system can be achieved. This effect
was predicted earlier for backward-wave (double-negative or Veselago) slab
lenses. The alternative system considered here is proved to be realizable at
microwaves by grids or arrays of resonant particles. The necessary
electromagnetic properties of the resonating grids and the particles are
investigated and established. Theoretical results are supported by microwave
experiments that demonstrate amplification of evanescent modes.
