We report the results of a Snell's law experiment on a negative index of refraction material in free space from 12.6 to 13.2 GHz. Numerical simulations using Maxwell's equations solvers show good agreement with the experimental results, confirming the existence of negative index of refraction materials. The index of refraction is a function of frequency. At 12.6 GHz we measure and compute the real part of the index of refraction to be -1.05. The measurements and simulations of the electromagnetic field profiles were performed at distances of 14lambda and 28lambda from the sample; the fields were also computed at 100lambda.

A plano-concave lens with negative index of refraction has been designed and fabricated. Such lenses have been postulated for many years, but only recently has their realization been made possible through improved simulation and fabrication procedures. We report here the simulation, fabrication, and performance of such a lens. The lens images the source field and reproduces the results of standard Gaussian optics. The curved lens with negative index of refraction in the microwave frequency region of the electromagnetic spectrum has been compared to a plano-convex Macor positive index of refraction lens having the same radius of curvature.

Negative index of refraction materials have been postulated for many years but have only recently been realized in practice. In the microwave region these materials are constructed of rings and wires deposited on a dielectric substrate to form a unit cell. We have constructed, experimentally characterized and simulated several of these structures operating in the 10 - 15 GHz range. Our simulations using Maxwell's Equations solvers have included wire arrays, ring arrays and assemblies of unit cells comprised of rings and wires. We find good agreement between the numerical simulations and experimental measurements of the scattering parameters and index of refraction. The procedure was to first model ring and wire structures on the unit cell level to obtain scattering parameters from which effective å, ì and n were retrieved. Next an assembled array of unit cells forming a 12 degrees wedge was used for the Snell's Law determination of the negative index of refraction. For the structure examined the computed value of n is within 20% of the one experimentally measured in the Snell's Law experiment from 13.6 to 14.8 GHz.