Design of a new open-type active electromagnetic metamaterial for magnetic field control based on numerical method

Controlling magnetic field with active electromagnetic metamaterial (AEM) consisting of a group of wires with precise arrangements of currents, essential for a wide range of applications, is limited by the structure where the source is fully surrounded by the concentric cylindrical AEM. We propose an open-type AEM design method based on the transformed medium theory and finite-element calculation method to overcome this stringent limitation. We experimentally demonstrate that an open-type AEM with negative magnetic permeability controls the magnetic field of a straight current wire at a distance outside the AEM. Our strategy leads to focus on the magnetic field in empty space with various structural forms and may broaden the application scope of electromagnetic metamaterials.