Electromagnetically coupled resonators using toroidal ferrite core for wireless power transfer

Wireless power transfer technology via electromagnetic resonant coupling shows the probability of removing wires. Many researches have been published and have shown promising results. However, there were few efforts to lower resonance frequency. A low operating frequency in a system is a very important parameter because the lower operating frequency could reduce a system price. We lowered a self-resonant frequency until 500KHz by using a toroidal ferrite core and measured transmission parameter by a vector network analyzer. We achieved a transmission parameter of over 0.5 in a range of antenna diameter and improved the efficiency in the short range with rotating antenna angle.