Optimization using transmitting circuit of multiple receiving antennas for wireless power transfer via magnetic resonance coupling

Electromagnetic resonance coupling technology has received more attention than other wireless power transfer technologies due to its capability to transfers energy across large air gap with high efficiency. The fundamental characteristics of a paired transmitting antenna and receiving antenna have been examined. However, in practical use, more than one receiving antenna is sometimes used, and some applications require multiple receiving antennas. In particular, this electromagnetic resonance coupling technology is desirable for powering multiple receiving antennas simultaneously because it is robust to displacement. In this paper, the multiple antennas efficiency optimization by transmitting circuit considering effect of cross coupling and sign of mutual inductances, are proposed. The equivalent circuits for multiple antennas enable calculation of impedance matching circuit´s parameters which will be used to optimize the transmitting antenna to achieve high efficiency. The equivalent circuits for multiple antennas enable to calculate high efficiency and it is optimized by changing transmitting circuit. This is also verified by electromagnetic field analysis, experiment and equivalent circuit theory. Proposed method is suitable for designing multiple antenna power supply system.