Abnormal refraction of microwave in ferrite/wire metamaterials

We report the experimentally observed abnormal refraction in metamaterials (MMs) consisting of ferrite rods and metallic wires with two kinds of configurations. Negative refraction (NR) and positive refraction (PR) are demonstrated in an MM constructed with parallel-arranged rods and wires. The frequencies of both NR and PR can be adjusted dynamically and together by an applied magnetic field and the PR occurs at frequencies slightly lower than that of the NR. The NR is attributed to simultaneously negative effective permittivity and permeability, and the PR is resulted from positive effective permittivity and permeability with the positive effective permittivity originating from electromagnetic coupling between the closest rod and wire. By making the rod cross the wire to reduce the coupling, we observed sole NR in an MM consisting of the cross-arranged rods and wires. Theoretical analysis explained qualitatively the abnormal refraction behaviors of microwave for the two kinds of MMs and it is supported by the retrieved effective parameters and field distributions.