Low-microwave-permeability metamaterials formed by millimeter-sized metal coils

Based on the characteristics of inductance, resistance and capacitance of millimeter-sized metal single-turn (or multi-turn) coil, it is predicted that array formed by millimeter-sized metal coils with high-density distribution may hold near-zero permeability in a broadband of microwave frequency range. Simulations and experiments show that real part of relative permeability of ring-shaped array formed by copper coils is smaller than one and will decrease with the increase in either cross-sectional area or number of the coils; the imaginary part of the permeability remains small always, which is consistent with theoretical analysis. Our work may provide a convenient way to fabricate the broadband low-microwave-permeability metamaterials with low energy losses by using millimeter-sized single-turn (or multi-turn) coils.