Date of Award

10-11-2024

Publication Type

Dissertation

Degree Name

Ph.D.

Department

Electrical and Computer Engineering

Keywords

5G;Antenna;Energy Harvesting;IoT;Radio Frequency;Sensors

Supervisor

Rashid Rashidzadeh

Supervisor

Roberto Muscedere

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

The proliferation of low-power Internet of Things (IoT) sensors has accelerated in recent years, driven by advancements in wireless technology and high-speed mmWave communications. These sensors facilitate real-time data transmission and reception across various applications, such as smart buildings, medical monitoring, surveillance, and autonomous vehicles. IoT devices primarily rely on batteries, and their lifespan is significantly influenced by the volume of data they transmit and the frequency of their operations. Battery replacement and maintenance for IoT sensors are both costly and time-intensive. Ambient energy harvesting offers a promising solution to this challenge by reducing maintenance costs and enabling self-sustaining IoT sensor nodes suitable for remote locations. As IoT sensors become more compact and energy-efficient, the design of energy-harvesting circuits becomes increasingly critical. Researchers are focusing on techniques to extract energy from radio frequency (RF) signals to address this need. This approach is particularly advantageous because RF energy is ubiquitous, even in remote areas and locations without light. This availability makes it possible to power IoT sensors in diverse environments where other energy sources might not be accessible. This dissertation presents an efficient RF-to-DC converter that prominently features a novel matching network. Serving as a high-gain passive voltage amplifier, the matching network significantly boosts the induced voltage across the antenna, thereby enhancing RF-to-DC conversion efficiency. Additionally, a 4×4 Butler matrix beamforming network connected to a 2×4 microstrip array patch antenna, operating at 5.8 GHz to enable directional signal transmission is designed. An optimized high-efficiency Dickson rectifier circuit is also designed to convert RF signals to DC over a wide dynamic range at high frequencies. This rectifier is particularly effective for low-power, high-frequency applications due to its voltage multiplication and reduced losses. To mitigate the effects of parasitic capacitance associated with conventional capacitors, interdigital capacitors (IDC) are designed on an FR-4 substrate. This design minimizes parasitic effects and improves the overall performance of the energy harvesting system. The proposed RF-to-DC converter modules were designed and simulated using Advanced Design System (ADS) software and subsequently fabricated on PCBs with an FR4 dielectric. Experimental results demonstrate the effectiveness of these innovative approaches. The RF energy harvester in this work is implemented using microstrip lines to construct the matching circuit, achieving superior RF-to-DC conversion efficiency. The circuit is notable for its simplicity, reduced complexity, and minimal component count, making it highly suitable for powering low-power IoT sensors.

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