Diode-like asymmetric transmission of linearly polarized waves through twisted split-ring metamaterial structure

In this paper, we propose a novel chiral metamaterial structure that enables asymmetric electromagnetic (EM) waves propagation. The metamaterial is composed of two metallic sheets with periodic split-ring resonator structures on both sides of a dielectric substrate. By full-wave EM simulations and free space measurements, strong diode-like asymmetric transmission of linearly polarized EM waves through such a thin metamaterial slab, has been demonstrated in the microwave band. It allows transmission of linearly polarized EM wave in one direction, while no transmission in the opposite direction. Such phenomenon is due to the strong cross-polarized conversion in the chiral slab with a thickness of one-fifteenth the operational wavelength that could rotate the linear polarization of the incident waves to its orthogonal polarization.