Magnetic field shielding by metamaterials

Abstract

Magnetic field shielding at low frequencies is a problem of high importance that is known for a long time. Metamaterials, which are known from fancy applications such as the so-called perfect lens and cloaking, also offer a new way to create effcient magnetic shielding by means of anisotropic metamaterials with low permeability in one direction. Such metamaterials can be constructed by assembling arrays of relatively simple LC circuits. In this paper, we analyze different metamaterials and show how they may be designed. We show that typical resistive losses in the coils and capacitors of the LC circuits reduce the shielding quality. Then, we consider the possibility of active electronic loss compensation and discuss the drawbacks of this concept. After this, we propose a purely passive way that benefits from the inhomogeneity of the magnetic field to be shielded. Finally, we present experimental results, which show the performance of metamaterial shields.