Design of a Conformal and Low-Frequency Metasurface for Magnetic Field Shielding in Wireless Power Transfer Systems

This paper investigates the use of an arbitrarily conformal and low-frequency metasurface for magnetic field shielding in Wireless Power Transfer (WPT) systems. Firstly, we carry out the metasurface design by employing an analytical approach, which enables the manipulation and customization of its response, despite the finite nature of the array and the near-field excitation. In particular, we are able to set a 180° phase shift between the current flowing in the WPT active RF driver and those in the metasurface unit-cells. In this way, the metasurface, by interacting with the driver, will produce a magnetic field opposite to the inducing one, accomplishing the desired shielding behavior. Then, a numerical set-up is designed to demonstrate the validity of the proposed approach. The results, obtained through accurate full-wave simulations, show that is possible to achieve a maximum level of shielding effectiveness of approximately 8 dB. The study demonstrates the potential application of conformal magnetic metasurfaces for enhancing WPT systems safety, thereby addressing certain constraints associated with existing devices.