Diamond-shaped hole array as a fishnet metamaterial for negative refraction

In this paper, a new design of hole array in a double-layer periodic arrangement is introduced and investigated both numerically and experimentally for the negative refractive index. The structure shows similar behavior to that of the corresponding fishnet metamaterials. The effective constitutive parameters are revealed by using retrieval procedure to verify the negative refraction nature of the proposed structure. A relatively high figure of merit (FOM = -Re (n)/Im (n) =70.05) is achieved at the K-band (18-26.5) frequency region. Finally, a rescaled design is presented to demonstrate the capability of structure for high frequency regime.