RF Energy Harvesting Antennas for IoT Applications

Abstract

Radio Frequency (RF) energy harvesting has become a widely researched area in the last few years. Ambient RF energy available in the environment is an efficient and convenient alternative to existing energy sources. With the advancement in the field of Internet of things (IoT) more and more sens ing devices are being deployed in remote areas for information gathering and control. Wireless powering of IoT devices is important to make them self stainable, portable and more efficient. Due to the wide availability of RF signals in the environment, RF energy harvesting is a promising solution for this purpose and can be used for the efficient charging of low power IoT de vices like Wireless Sensor Networks (WSNs), wireless medical implants and smart devices etc. An RF energy harvester or Rectenna consists of two parts; An antenna that receives the RF signals and a rectifier that converts them into DC voltage. The two are connected via a wideband/multiband matching network to re duce losses. The major challenges of energy harvesting today are the design of broadband antennas and rectifiers that can harvest energy from multiple sources. This research presents a rectenna design that can harvest RF energy from multiple broadcasting and mobile communication sources simultaneously. In this thesis multiband antennas for RF energy harvesting have been designed to scavenge energy from FM, GSM900, GSM1800 and Wi-Fi (2.4 GHz) band. Multiple antennas have been designed and integrated with rectifier in a 3- dimensional cubic structure to harvest energy from all directions with greater gain. An end to end system has been demonstrated to power up IoT based sensors.