Microwave power transmission using a signal-to-leakage-and-noise ratio to protect wireless communication devices

Microwave Power Transmission (MPT) is a promising technology that can be utilized to charge devices wirelessly and remotely. However, most previous studies on MPT focused on improving charging efficiency and have ignored the harmful effects on wireless communication devices that are sensitive to the considerable received signal power caused by the electromagnetic radiation of microwaves. To resolve this problem, this study introduces into MPT the signal-to-leakage-and-noise ratio (SLNR), used to suppress co-channel interference in multi-user Multiple-Input Multiple-Output (MIMO) downlink communications. We establish a beamforming scheme that maximizes SLNR for MPT. Compared with a beamforming scheme that does not consider leakage power, the proposed method transmits power to intended receivers while suppressing leakage power to protected devices. Based on simulations, our method decreases the leak power to protected devices by over 10 dB while maintaining the received power at the targeted receivers, compared with the conventional method.