Wireless power transfer system minimizing an influence of a desk

A wireless power transfer system using both a resonant coil and a loop element has been reported. In this report, both a transmitter and a receiver are composed of a resonant coil and a loop element. In another report, only a loop element is employed for a receiver, and the configuration of the receiver is simplified. If there is a mutual coupling between the resonant coil and a surrounding object, a resonant frequency of the resonant coil is shifted. In particular, when a material of the surrounding object is a metal, the resonant frequency of the resonant coil is shifted significantly. When a frequency of the transmitter is restricted in narrowband, the transfer efficiency of the system becomes small. For example, when the transmitter of a wireless power transfer system for a mobile terminal is put on a steel desk, the transfer efficiency of the system becomes small. In this paper, a wireless power transfer system is proposed to minimize the influence of the desk. A transmitter of the proposed system is put on the desk. A receiver of the proposed system is put on the transmitter. Exploiting its thinness, a receiver of the proposed system is installed in a mobile terminal. The effectiveness of the proposed system is confirmed by the measurement data.