An Efficient Low-Power Rectifier Integrated Antennas for Rf Energy Harvesting and Autonomous Frequency Reconfiguration

Abstract

Various rectifier integrated antenna (RIA) structures are investigated in a search for new RF energy harvesting devices which might be useful for state-of-the-art multi-purpose energy harvesting and autonomous frequency reconfiguration applications. Starting from intuitive concepts to novel RIA device designs, their fabrication procedure, op- timization, and characterizations of these device structures have been carried out within the scope of this thesis. Modern wireless power transmission and energy harvesting technology demand low power, adaptive switching, and high RF to DC conversion ef- ficiency rectifier integrated antennas. To achieve these requirements, various rectify- ing antenna designs like open-loop slot line resonators, monopole, symmetrical slot, and variable feed length-based modified geometrical structures are demonstrated, fab- ricated, and compared the various results with similar kinds of structures reported in the literature. In addition, periodic metamaterial array-based metasurface is utilized as receiving antenna for maximum capture of ambient electromagnetic energy which provides high absorption efficiency, polarization-insensitive, and wide-angle reception. This thesis focuses on high efficient low power RIA designs, which give stable out- put DC voltage for continuous supply to electronic devices. We first demonstrated the rectifier integrated wideband monopole antenna and rectifier integrated dual-band mod- ern Aztec quatrefoil geometrical slotted structure for energy harvesting. The symmetri- cal geometry single band with harmonic suppression and multiband slotline structures are introduced with optimum feed length backed by different reflector structures for consistent unidirectional radiation performance and enhanced gain. In general, a full copper patch reflector is placed behind the antenna at a distance of λ/4, where λ is the free space wavelength at the lowest frequency. Instead of a full copper patch reflec- tor, an artificial magnetic conductor (AMC) and defected reflector structure (DRS) are introduced to reduce the profile of the antenna and enhanced gain. These designs ef- iii fectively capture the ambient electromagnetic energy from low input power levels and transferring to rectifying circuit for further conversion into DC. After successful demonstration of wideband/dual-band rectifier integrated antennas and multiband rectifier integrated antennas with enhanced gain, novel designs of fre- quency reconfigurable rectifier integrated antennas with differential configuration for receiving and rectifying the differential (two signals with equal amplitude and 1800 phase difference) radio frequency signals and a slotline open-loop resonators based fre- quency reconfigurable antenna with autonomous switching of frequency bands have been demonstrated. In addition, an ultra-wideband (UWB) crescent moon shape slotted monopole an- tenna with diplexer and rectifier has been demonstrated for simultaneous microwave energy harvesting and data communication applications. The antenna is composed of four symmetrical circularly slotted patches, a feed line, and a ground plane. A slotline open-loop resonator-based diplexer is implemented to separate the required signal from the antenna without an extra matching circuit. A microwave rectifier based on the volt- age doubler topology is designed for RF energy harvesting. The overall performance of the antenna with a diplexer and rectifier is also studied, and it is found to be suitable for SWIPT applications. Finally, a tri-band metamaterial periodic unit-cell array-based rectifying metasur- face has been investigated for receiving and rectifying the electromagnetic energy from wide-angle and all polarizations. The configurations of antenna design and simula- tion of various parameters are carried out by using Computer Simulation Technologies (CST) Microwave Studio, fabricated using the S103 Proto Mat LPKF PCB machine, and measured using the Agilent Technologies E8363C PNA network analyzer. Simi- larly, the rectifier design and simulations are carried out by using Keysight Technologies Advanced Design System (ADS) high-frequency RF simulator.