Negative refraction using true left-handed metamaterials
Left-handed materials and negative refraction attracted a great amount of attention in recent years due to their unique physical properties. It is possible to obtain a left-handed material by combining a novel artificial structure (split ring resonator) and a wire structure periodically. We investigated the transmission and reflection properties of split ring resonators (SRR), wires and composite metamaterials consisting of SRR and wire structures. We have successfully demonstrated true left-handed behavior in free space with a high transmission peak (-1.2 dB). This is the highest transmission peak reported for a left-handed material. The left-handed transmission band coincides exactly with the region where both dielectric permittivity and magnetic permeability have negative values. We proposed and demonstrated a new method to distinguish the magnetic resonance of the SRR structures. We experimentally confirmed that composite metamaterial has a negative refractive index, at the frequencies where left-handed transmission takes place. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments (-1.87) and the phase shift experiments (-1.78) are in good agreement.