Design of unit cell for metamaterials applied in a wireless power transfer system

Magnetic superlens is a homogeneous and isotropic solid planar slab with negative permeability (usually -1) and can be applied in a wireless power transfer system to enhance the power transfer efficiency. Metamaterials with negative permeability could be achieved by split-ring resonators (SRRs). To be applied in wireless power transfer systems, the metamaterials need to be low loss, low cost, compact and capable of high power, so we usually use a variant of SRRs - plane spirals printed on PCB board as a metamaterial unit cell. The plane spirals can reduce the size of the unit cell relative to the wavelength because it introduces much more capacitance than SRRs. In this paper, we propose a guideline to design the unit cell for the magnetic superlens. We demonstrate how the parameters of the unit cell affect its effective permeability and how the effective permeability of the metamaterial slab affects its performance in a wireless power transfer system.