Performance enhancement of wireless power transfer rectenna system for IoT applications

Abstract

The rapid growth of the Internet of Things (IoT) has led to an increased demand for monitoring various types of data for different applications, including home automation, smart cities, and industrial applications. However, due to the limited battery capacity of IoT sensor nodes, replacing or recharging a large number of batteries can be prohibitively costly and labor-intensive. Therefore, Wireless Power Transfer (WPT) is a potential option that uses a dedicated RF transmitter (Tx) and a rectenna (Rx) system deployed at the IoT sensor node for remote battery recharge or even battery-less operations. However, real-world applications continue to necessitate the optimal design of a rectenna. The cutting-edge designs suffer from significant research problems such as angular misalignment, non-uniform 3-D coverage, and non-scalability in WPT rectenna systems. This thesis is divided into seven chapters. The first two chapters present the research problems and a fundamental description of WPT rectennas. Chapter 3 presents an analytical framework for mitigating angular misalignment by driving specific conditions on the DC power pattern. Following the analytical framework, three antennas with omnidirectional capabilities in the azimuth plane are designed to improve power conversion efficiency (PCE). Furthermore, chapter 4 analyzes the non-uniform coverage of the transmitter (Tx) by employing two novel fully integrated planar multi-sector rectenna arrays to obtain substantially uniform 3D spherical DC coverage. Chapter 5 presents dynamic power harvesting and polarization-insensitive operations employing a scalable plug-in-type WPT system. The scalable technique eliminates the need to design various rectenna modules if the energy needs or orientation of the sensor nodes change in an IoT application, resulting in a low-cost system. Chapter 6 presents several WPT-enabled IoT antennas for long reading range, robustness, and platform tolerance. Chapter 7 presents the conclusion and future work in the WPT rectenna system. Thus, this thesis presents a new WPT system that can be used for future applications that require efficient WPT.