Double bands of negative refractive index in the left-handed metamaterials with asymmetric defects

The authors present a left-handed metamaterial (LHM) with asymmetric defects at microwave frequencies. The LHM is composed of the periodic arrays of hexagonal split ring resonators and wires, and the defects are introduced into the integrated LHM. It is shown with beam shifting experiment that the transmittance spectrum of the sample appears to have two peaks with maximum value frequencies of 9.10 and 9.80 GHz, and double bands of negative refractive index, n=-0.48 and n=-1.09, are clearly found. The LHM proposed here offers the potential applications such as bandpass filters, wavelength divider, and antennas.