Figures of merit study

Medical implants that require recharging typically use magnetic resonant coupling of transmit (external) and receive (internal) RF coils. When designing the wireless power transfer (WPT) system, we strive to increase the efficiency of the system, that is to increase the transmitted power per unit RF input power. The efficiency of the WPT system depends on the efficiency of the transmit RF coil and receive RF coil. In this paper, we derivethe values that serve as figures of merit for the RF coils. Additionally, we demonstrate how to experimentally measure these values in the lab.