Experimental verification of backward-wave radiation from a negative refractive index metamaterial

A composite medium consisting of an array of fine wires and split-ring resonators has been previously used to experimentally verify a negative index of refraction. We present a negative refractive index (NRI) metamaterial that goes beyond the original split-ring resonator/wire medium and is capable of supporting a backward cone of radiation. We report experimental results at microwave frequencies that demonstrate backward-wave radiation from a NRI metamaterial—a characteristic analogous to reversed Cherenkov radiation. The conception of this metamaterial is based on a fresh perspective regarding the operation of NRI metamaterials.