Asymmetric Strongly Coupled Printed Resonators for Wireless Charging Applications

This paper presents a simple compact design for wireless charging applications using asymmetric strongly coupled printed resonators (SCPR). The proposed resonators are further loaded by surface mounted (SMD) capacitors for miniaturization. The system consists of two substrates. The first transmitting substrate contains a driving loop on the top layer and the high Q-resonator on the bottom layer. Similarly, the second substrate contains the high Q-resonator as the receiver and a loop as the load. An equivalent circuit model is extracted. An analytic design method is proposed to get a high wireless power transfer (WPT) efficiency. Good agreement between electromagnetic simulations, circuit simulations, and measurements was achieved. The proposed system achieves a measured WPT efficiency of 60% at 100 MHz using a receiving resonator of size 20 mm x 20 mm away for a transmission distance of 35 mm from the transmitting resonator of size 30 mm x 30 mm.