Ambient RF powered wireless sensor system

Abstract

Energy harvesting is a promising technology for providing an alternative and environmental friendly way to gather energy from the environment. It can potentially alleviate the requirement for battery replacement in IoT systems. Ambient RF energy harvesting, which makes use of ambient RF signals, from human made sources, is a potential approach for energy harvesting that is the focus of this thesis. In this work, I investigate and successfully build an ambient RF powered wireless sensor system, which is powered solely by ambient RF energy. The system includes an antenna for harvesting RF signals, rectennas to convert the harvested electrical energy from ac to dc, PMU to manage and stored the collected energy into a supercapacitor, and a MCU board with a sensor to act as a IoT sensor node powered by the system. A central station is also required to collect the data from each node once they are available. Two prototypes are built, where one is operating at GSM-900 with a larger size and the other one operating at GSM-900, GSM-1800 and UMTS-2100, for comparison. The system can operate automatically from cold start with background ambient power as low as to - 30dBm or lower if cold start is not required. Comprehensive experiments have been undertaken to demonstrate the effectiveness of the system. This includes a university campus, off campus setting and a controlled laboratory environment. With the experiments taken at multiple locations, it is demonstrated that ambient RF energy harvesting is able to power IoT devices, providing a batteryless solution for IoT development.

Date of Award	2022
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Ross MURCH (Supervisor) & Frankie CHIU (Supervisor)