Selective Microwave Wireless Power Beaming for Multiple Devices Using Backscatter CDMA

Microwave power transmission technology using distributed antenna systems is being researched and developed. The distributed WPT system optimizes the transmission phase and supplies higher power by feeding back fluctuations in received power at receivers to the transmit side. In this study, by using a spread spectrum signal as a backscatter signal, independently receiving feedback signals in the same frequency from multiple receivers, similar to the CDMA system was realized. To implement the CDMA system, we implemented a circuit in the power receiver using a CPLD to generate the Gold sequence, which is a spreading code. On the transmitter side, a demodulator for the superimposed spread spectrum was implemented in the power transmission system using DLL. The proposed WPT system was constructed by integrating the developed power receiving terminal and power transmission system. We confirmed the constructed system can selectively supply power to multiple receivers.