Gains maximization via impedance matching networks for wireless power transfer

Wireless Power Transfer (WPT) based on resonant magnetic coupling is an attractive technology for enabling the wireless recharge of electric devices and systems. One of the main drawbacks of this technology is related to the dependence of the efficiency and the power delivered to the load on possible variations of the coupling coefficient and load impedance. In order to alleviate the effects of this dependence, the optimization of appropriate adaptive matching networks is proposed in this paper. The three power gains usually adopted in the context of two-port active networks are assumed as figures of merit in the optimization process. It is theoretically and experimentally demonstrated that the maximum realizable gain of the link is achieved when the conjugate image impedance matching is realized by appropriate matching networks at both the input and output ports of the WPT link