A Broadband High-Gain Multibeam Ambient Millimeter-Wave Energy-Harvesting System

The rapid development and proliferation of millimeter-wave (mmWave) networks have significantly boosted interest in wireless energy harvesting within this band. This article delineates a novel broadband, high-gain, multibeam ambient mmWave energy harvesting system. The system incorporates a modified Luneburg lens, a dual-polarized ME-dipole rectenna array, and a simple dc combiner to adeptly address the challenges associated with battery charging and replacement within the scope of industrial Internet of Things (IoT) applications. The system leverages frequency, spatial, and polarization diversity to optimize mmWave energy harvesting. The modified Luneburg lens realizes RF combination and multibeam characteristics, while a simplified rectifier network allows for efficient energy conversion. The antenna array has 29 antenna elements, each achieving 50% relative bandwidth covering 24–40 GHz. Beams have a gain of up to 27 dBi, providing 130° of 3-D spatial coverage. The rectifier design has been validated for high RF-to-DC efficiency across the operating frequency. Our prototype shows the system can provide an output dc voltage of 3.5 V, an output dc power of 6 dBm, and an RF-to-DC efficiency of about 40% when two transmitters produce a power density of 0.15 mW/cm2.