RF energy harvesting for energy autonomous IoT devices

Also providing a view of scalable metamaterial based RF harvesting towards Watt harvesting.<br><br>In parallel, new superdirective rectenna arrays are presented that achieve realised gains exceeding 7 dBi from electrically small apertures. Using parasitic loading and phase-only optimisation, these arrays overcome the efficiency and complexity barriers traditionally associated with superdirectivity. A steerable five-element design further enables 360° beam coverage, maximising sensitivity to weak RF sources without bulky matching networks or amplifiers.<br><br>Finally, the work emphasises system-level co-design, integrating radiating structures with rectifying circuits to maintain efficiency at ultra-low input powers, below −20 dBm.

Fabricated prototypes validate the concepts experimentally, achieving state-of-the-art performance for ambient RF harvesting. <br><br>Together, these contributions establish new methodologies for compact and practical rectennas. By combining metamaterial absorption with superdirective gain, the thesis demonstrates pathways toward scalable, battery-free IoT devices and autonomous wireless systems, with applications in smart cities, environmental monitoring, industrial automation, and biomedical technology.