Electromagnetic cloaks are devices that make objects undetectable for probing with electromagnetic waves. The known realizations of transformational-optics cloaks require materials with exotic electromagnetic properties and offer only limited performance in narrow frequency bands. Here, we demonstrate a wideband and low-loss cloak whose operation is not based on the use of exotic electromagnetic materials, which are inevitably dispersive and lossy. Instead, we use a simple structure made of metal layers. In this Letter, we present an experimental demonstration of cloaking for microwaves and simulation results for cloaking in the visible range.

We consider a novel method of cloaking objects from the surrounding electromagnetic fields in the microwave region. The method is based on transmission-line networks that simulate the wave propagation in the medium surrounding the cloaked object. The electromagnetic fields from the surrounding medium are coupled into the transmission-line network that guides the waves through the cloak thus leaving the cloaked object undetected. The cloaked object can be an array or interconnected mesh of small inclusions that fit inside the transmission-line network.

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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.