Design of radio frequency harvesting system for wireless communications
Energy harvesting (EH) is a technique of collecting energy from ambient radio frequency (RF) sources to operate small sensors and devices without batteries. Harvesting energy from the environment is an alternative and cost-effective approach because it reduces the dependency on battery-operated syst...
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| Format: | Thesis |
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2022
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| Summary: | Energy harvesting (EH) is a technique of collecting energy from ambient radio frequency (RF) sources to operate small sensors and devices without batteries. Harvesting energy from the environment is an alternative and cost-effective approach because it reduces the dependency on battery-operated systems significantly. However, the performance and potential of an EH system depend on the design strategy and sensitivity. Therefore, significant research is still ongoing in this area to meet the increasing demand for wireless applications. In this research, the goal is to harvest ambient RF energy and convert it into direct current (DC) electrical energy in an ambient environment. This objective leads to developing the concept, feasibility analysis, design, and implementation where the energy is harvested efficiently from available RF sources. An RF spectral survey in various locations was performed inside the area of the Multimedia University of Cyberjaya, Malaysia within the frequency spectrum of 0.5–3.0 GHz. The approach of harvesting RF energy over multiple frequency bands was investigated to improve the sensitivity and enhance the DC output power. In this research, a quad-band RF harvester was proposed, where good impedance matching and antenna efficiency were obtained, which maximized RF energy harvesting. A maximum power point tracking system or a boost converter was introduced, which controls the scanning of available frequency bands, optimizes the rectenna performance, and ensures that energy is harvested at maximum efficiency. Additionally, the proposed design provides a maximum DC rectification efficiency of 70.02% with an RF input of -20 dBm and more than 40% fractional bandwidth. The rectifier that was designed to implement this system could produce 464.5 mV by harvesting RF energy simultaneously, according to practical measurements. Moreover, this research deals with an overview of the ultra-wideband hybrid (RF and solar) EH technique, design, and implementation of the prototype. The prototype of the hybrid harvester demonstrated that with 360 lux ambient light intensity, the solar cell could generate 122.5 mV energy while the harvester could attain an extra 5–48% energy with ambient RF input level variation from -10 to -20 dBm. Different factors, such as various frequency spacings, low RF input energy levels, and incoherent phase arrangements, were addressed in frequency domain analysis and measurements. |
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