Wirelessly Powered IoT Sensor Facilitated by A Planar Electrically Small Huygens Rectenna

A wirelessly powered Internet-of-Things (IoT) sensor system is presented in this paper. It is facilitated by a highly compact, planar electrically small Huygens rectenna. The rectenna is based on two metamaterial-inspired electrically small structures, an Egyptian axe dipole (EAD) and a capacitively loaded loop (CLL). The near-field resonant parasitic EAD and CLL structures are carefully designed to be a compact entity that excites a short dipole. A highly efficient rectifier circuit is seamlessly connected to this driven dipole, forming a rectenna. The whole rectenna system is fabricated on a single piece of PCB substrate. It is electrically small, has an ultra-thin profile, and is low cost and lightweight. The developed rectenna is able to wirelessly power IoT devices to realize battery-free systems. A wirelessly powered light detection sensor system is successfully demonstrated by augmenting the rectifier with a photocell.