Multiband Ambient RF Energy Harvesting for Autonomous IoT Devices

This letter presents a novel multiband rectenna for the ambient wireless energy harvesting of an autonomous internet of thing (IoT) sensor. A bow-tie antenna with slits is proposed to obtain four frequency bands at 840 MHz, 1.86, 2.1, and 2.45 GHz, respectively. Furthermore, a multiband rectifying circuit combined of four single ring-loop rectifiers is designed with high conversion efficiency. Finally, a power management circuit with storing and converting the harvested voltage is proposed for smoothing dc output voltage. The energy harvester can be used in practical wireless sensor applications.