Chiral structure based on bilayered displaced U pair

A type of bilayered chiral structure is introduced. Whereas common bilayered chiral structures are based on rotation, our design is based on the displacement between two U topologies on different layers. This displacement breaks the symmetry of the pattern and generates the chirality. Prototypes are fabricated in the microwave frequency band. Simulated and measured results agree well. Both optical activity and circular dichroism are observed for circularly polarized waves. The amplitude and phase differences for the transmission coefficients of the circularly polarized waves can reach more than 12 dB and 40° at about 13.4 GHz, respectively. Since the chirality of the bilayered structure can be easily controlled by moving the position of one of the two layers, this topology can be used in the designing of tunable chiral metamaterials