Dynamic Energy Beamforming for Multiple IoT Devices With Frequency Diverse Array

We propose a beamforming scheme called dynamic energy beamforming with a frequency diverse array (DEB-FDA) for enhancing the energy harvesting performance of multiple Internet of Things (IoT) devices in radio frequency-based wireless power transfer systems. We adopt the frequency diverse array (FDA) architecture, where the steering vector is a function of the distance and angle, to synthesize beam patterns that depend on both these parameters. We formulate an optimization problem for designing the transmit-beamforming vector and the frequency components of the FDA so that constructive interference occurs simultaneously at the locations of multiple IoT devices. We then develop an algorithm for dynamic energy beamforming based on alternating optimization using the minorize-maximization algorithm. Simulation results show that the proposed DEB-FDA scheme improves the energy harvesting performance of IoT devices in multiple locations.