Negative refractive index in split ring resonators

Artificially engineered metamaterials have become of considerable interest because extend the electromagnetic properties of conventional materials. To metamaterials, negative refractive index and artificial magnetism are two specific types of behavior that have been demonstrated over the past few years. In this work we have designed and constructed materials with negative refractive index in the microwave region. Here we show that there are frequencies in the split ring resonators (SRR) in which the real part of the refractive index has negative values, the last thing because the direction of the phase velocity is antiparallel to the group velocity. We present simulation results, where we used MEFiSTo, to determining the characteristic resonance frequency for circular and square split ring resonators. For this purpose we used the power curves as a function of frequency. These quantities depend primarily on the dimensions and morphology of the cells used. In the experiment, we employed a signal generator and a spectrum analyzer with an operating frequency from 20 Hz to 20 GHz, and arrangements of circular and square SRR.