Numerical Study On Negative Refractions In Metallic Metamaterials

Artificial materials with simultaneously negative permittivity and permeability, namely, left-handed materials (LHM), are currently one of the most scientifically interesting topics because of their unusual properties to those conventional electromagnetic media, such as negative refraction and sub-diffraction-limited imaging by planar slab. In this dissertation, numerical simulations, based on full-wave finite element method, are performed to investigate mainly the metallic metamaterials in terms of wedge-based negative refractions, backward phase propagations, flat slab imaging, and scattering parameter calculations.Although it was claimed experimentally that the composite metamaterial comprising metallic split-ring resonators and wires (SRR-Wire) could respond in the way of LHM, there were still certain unclarities remained. It is our objective in the 3rd chapter to confirm numerically whether or not the so-called Snell's law experiments by wedge-shaped SRR-Wire metamaterials were originated from left-handed electromagnetic mechanism. In our work, a wedge-shaped structure made of SRR and wires is numerically simulated to evaluate its refraction behavior. Four frequency bands, that is, the stop band, left-handed band, ultralow-index band, and positive-index band, are distinguished according to the refracted field distributions. Negative phase propagation inside the wedge is also demonstrated in the left-handed band and the Snell's law is conformed in terms of its refraction behaviors in different frequency bands. Our results confirm that negative index of refraction indeed exists in such a composite metamaterial and thus provide a convincing support to the conclusions of previous Snell's law experiments.On the other hand, it was originally supposed that SRR-Wire metamaterials were left-handed just because it had negative permittivity of the wire array and negative permeability of the SRR array, without consideration of the potential interaction between the SRR and wire. Therefore, it was argued that there was deeper physical...