Electromagnetic behaviors in a bilayered metal helical structure

We studied both numerically and experimentally electromagnetic behaviors of a bilayered metal helical structure in the microwave-frequency. Two resonances are found in the transmission spectrum of the circularly polarized wave which has the same handedness with the helices. The resonance frequencies are almost independent on the distance between the two layers. In addition, the center frequency of full width at half-maximum (FWHM) in the transmission spectrum is approximately inversely proportional to the distance between the two layers.