A Dual-function Quasi-static Magnetic Device with Cloaking and Concentrating Functions Simultaneously

In previous study, many single-function static/quasi-static magnetic devices, such as cloak and concentrator, have been designed base on transformation optics. However, few have explored devices capable of simultaneously generating two different functions on the static/quasi-static magnetic field. In this study, we propose a dual-function quasi-static magnetic device, which can create a concealed region and concentrated region for quasi-static magnetic field simultaneously. The dual-function quasi-static magnetic device is designed via twice extreme spatial stretching transformation and magnetic null medium, which can be realized by using arrays of superconductors and ferromagnetic materials in specific arrangement. The simulated results verify the performance of the proposed dual-function quasi-static magnetic device, which can simultaneously achieve cloaking and concentrating effect for the magnetic field from DC to 1000 Hz. The quasi-static magnetic field can be enhanced 9 times than the background magnetic field when the side lengths of the internal square pillar and external square pillar of the proposed structure are selected as a = 10 mm and b = 90 mm, respectively. Moreover, the concentrating ratio obtained from theoretical calculation fits well with the results obtained through numerical simulation. The dual-function quasi-static magnetic device designed in this study may have essential application in medical testing for special occasions.