Simultaneous mid-range power transfer to multiple devices

Electromagnetic resonators strongly coupled through their near-fields A. Karalis, J. D. Joannopoulos, and M. Soljačić, Ann. Phys. 323, 34 (2008); A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher, and M. Soljačić, Science 317, 83 (2007) are able to achieve efficient wireless power transfer from a source to a device separated by distances multiple times larger than the characteristic sizes of the resonators. This midrange approach is therefore suitable for remotely powering several devices from a single source. We explore the effect of adding multiple devices on the tuning and overall efficiency of the power transfer, and demonstrate this scheme experimentally for the case of coupling objects of different sizes: a large source (1 m2 in area) powering two smaller devices (each ≃0.07 m2 in area).