Wave fields measured inside a negative refractive index metamaterial

Measured spatial variations of field phase and amplitude versus position inside a wire/split ring resonator negative refractive index metamaterial are presented that show that the phase velocity inside a negative index material points toward the source and consequently that phase velocity and energy flow are reversed in such a medium. These measurements directly demonstrate the fundamental behavior of electromagnetic waves in a negative refractive index material. The same internal field measurements are also used to accurately and reliably measure the effective bulk properties of the negative index metamaterial.