Practical applications of radiative wireless power transfer

For practical use of radiative wireless power transfer (WPT), it is necessary to design a system which is able to supply circuits with a dynamic loading characteristic. In this paper we present a practical way to obtain efficiency and dc output power characteristics of a WPT system. An Avago HSMS-2852 Schottky diode pair is used to rectify the RF power. The diode pair is matched to a 50 Ω input impedance and loaded with an Texas Instruments TI BQ22570 Power Management Circuit. The system is able to deliver 20 mW dc output power during 10 ms with a period of 8.7 s at an RF input power level of -10 dBm. This corresponds to a distance in excess of 9 m having a 6 dBi receiving antenna and using a 3 W EIRP transmitter at 868 MHz.