Design of a wireless energy harvesting system with a high polarization-purity circularly polarized array

Abstract

As the search continues for alternate forms of energy sources, one that shows great promise and feasibility is wireless energy harvesting (WEH), which is the ability to harvest radio frequency (RF) energy from ambient or dedicated sources. Wireless energy harvester systems aren’t known for harvesting large amounts of power, however, with the development of the Internet of Things (IoT), WEH technology is seen as a great source of energy for low power wireless sensors in IoT applications due to their ease of implementation and low cost. The purpose of this work is to design a WEH system at Wi-Fi band (2.45 GHz) and examine its efficiency to harvest RF energy from ambient and dedicated sourced. The system developed consists of a circularly polarized receiver patch antenna which uses a U slot configuration to achieve the desired polarization as well as a wide bandwidth, and a half wave rectifier circuit with an integrated matching network. For more efficient harvesting, a sequentially rotated 22 planar array using U-slot patch antenna elements is also designed. The antenna array not only increases the receiver gain compared to a system with a single receiver antenna, it also significantly improves the polarization purity of the receiver and thus the overall efficiency of the system. The above subsystems as well as a two-stage Dickson multiplier circuit is designed, simulated, and analyzed in CAD software. The design process for the aforementioned WEH system aims to lay a foundation for future work in the area of WEH so that the need for batteries and power cords in IoT sensor systems can be eliminated.