Scalable lens-enhanced broadbeam mmWave harvester delivering tens of milliwatts for wireless power transfer in next-generation smart city environments

As smart cities and next-generation connected environments continue to grow in scale and complexity, the need for sustainable, maintenance-free energy solutions becomes increasingly urgent. The widespread reliance on batteries to power billions of IoT devices poses significant challenges, including frequent maintenance requirements and substantial environmental impact. A compelling alternative involves harnessing 5G networks, which not only enhance communication capabilities but also enable efficient wireless energy harvesting. In this paper, the authors propose a scalable, broadband, dielectric lens-based mmWave energy harvester with wide total solid angular coverage and mW-level harvesting capabilities. The proposed system features a 'pixel' array of rectennas, each incorporating a circularly polarized aperture-coupled stacked patch antenna and a broadband, high-sensitivity rectifier, enhanced by a biconvex dielectric lens to achieve a wide solid angle coverage of 2.68 sr. The single unit cell, using a single transmitter setup, demonstrated a peak captured power of up to 20 mW. By scaling the design to a 2×2 structure, the proof-of-concept (PoC) harvester achieved up to 82 mW using a two-transmitter setup with incident power density of 0.25Formula: see text. When utilizing the full 75 dBm EIRP available at 5G/mmWave, the PoC 2×2 harvester can theoretically capture a peak power up to 105 mW in addition to harvesting mW levels of power at ranges extending up to 120 m. By combining high harvested power with broad-angle coverage, the proposed system outperforms existing state-of-the-art mmWave energy harvesters. With its broadbeam coverage and high efficiency, this architecture presents a compelling pathway to support next-generation smart city applications while minimizing dependence on conventional power infrastructure.