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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Power-efficient Radio Frequency Energy-harvesting Circuit

Khoury, Philip 10 January 2013 (has links)
This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.
2

A Power-efficient Radio Frequency Energy-harvesting Circuit

Khoury, Philip 10 January 2013 (has links)
This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.
3

A Power-efficient Radio Frequency Energy-harvesting Circuit

Khoury, Philip January 2013 (has links)
This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.
4

Antenna and rectifier designs for miniaturized radio frequency energy scavenging systems

Ding, Yi January 2015 (has links)
With ample radio transmitters scattered throughout urban landscape, RF energy scavenging emerges as a promising approach to extract energy from propagating radio waves in the ambient environment to continuously charge low power electronics. With the ability of generating power from RF energy, the need for batteries could be eliminated. The effective distance of a RF energy scavenging system is highly dependent on its conversion efficiency. This results in significant limitations on the mobility and space requirement of conventional RF energy scavenging systems as they operate only in presence of physically large antennas and conversion circuits to achieve acceptable efficiency. This thesis presents a number of novel design strategies in the antenna and rectifier designs for miniaturized RF energy scavenging system. In the first stage, different energy scavenging systems including solar energy scavenging system, thermoelectric energy scavenging system, wind energy scavenging system, kinetic energy scavenging system, radio frequency energy scavenging system and hybrid energy scavenging system are investigated with regard to their principle and performance. Compared with the other systems, RF energy scavenging system has its advantages on system size and power density with relatively stable energy source. For a typical RF energy scavenging system, antenna and rectifier (AC-DC convertor) are the two essential components to extract RF energy and convert to usable electricity. As the antenna occupies most of the area in the RF energy scavenging system, reduction in antenna size is necessary in order to design a miniaturized system. Several antennas with different characteristics are proposed in the second stage. Firstly, ultra-wideband microstrip antennas printed on a thin substrate with a thickness of 0.2 mm are designed for both half-wave and full-wave wideband RF energy scavenging. Ambient RF power is distributed over a wide range of frequency bands. A wideband RF energy scavenging system can extract power from different frequencies to maximize the input power, hence, generating sufficient output power for charging devices. Wideband operation with 4 GHz bandwidth is obtained by the proposed microstrip antenna. Secondly, multi-band planar inverted-F antennas with low profile are proposed for frequency bands of GSM 900, DCS 1800 and Wi-Fi 2.4 GHz, which are the three most promising frequency bands for RF energy scavenging. Compared with previous designs, the triple band antenna has smaller dimensions with higher antenna gain. Thirdly, a novel miniature inverted-F antenna without empty space covering Wi-Fi 2.4 GHz frequency band is presented dedicated for indoor RF energy scavenging. The antenna has dimensions of only 10 × 5 × 3.5 mm3 with appreciable efficiency across the operating frequency range. In the final stage, a passive CMOS charge pump rectifier in 0.35 μm CMOS technology is proposed for AC to DC conversion. Bootstrapping capacitors are employed to reduce the effective threshold voltage drop of the selected MOS transistors. Transistor sizes are optimized to be 200/0.5 μm. The proposed rectifier achieves improvements in both power conversion efficiency and voltage conversion efficiency compared with conventional designs. The design strategies proposed in this thesis contribute towards the realization of miniaturized RF energy scavenging systems.
5

Dispositif conformable de récupération d'énergie radiofréquence : vers l'autonomie des objets communicants / Development of rectenna on flexible and semi-rigid substrates for autonomous sensors

Berges, Romain 12 July 2018 (has links)
Parmi les principaux verrous à lever pour la mise en place de l’IoT, l’un des plus difficiles concerne l’autonomie des objets. Il est en effet difficilement concevable, vu le grand nombre de composants déployés, d’intervenir sur chacun pour remplacer, ou recharger, leur batterie. Dans ce contexte ma thèse a pour objectif de proposer des solutions éco-énergétique afin de rendre tout ou partie autonome des objets communicants, type capteur. Une des solutions est de développer des récupérateurs d’énergie radiofréquences fonctionnant aux fréquences dans la bande ISM, 900 MHz et/ou 2,4 GHz. Grâce aux modules de récupération d’énergie le capteur pourra fonctionner sur une période théoriquement illimitée, grâce à un module de stockage d’énergie embarqué rechargeable. En pratique, la fiabilité de l’élément de stockage définira le temps de vie du capteur, estimé à une vingtaine d’années avec les cellules de stockage rechargeables actuelles. Les solutions existantes dans le commerce sont presque exclusivement développées sur substrat époxy (ou dérivé). Cette solution est généralement robuste et performante. En revanche la rigidité mécanique du substrat réduit l’intégration des nœuds dans notre environnement, elle devient rédhibitoire dans le cas des réseaux corporels. Afin de permettre au capteur autonome de s’intégrer plus facilement, et d’adresser notamment des applications de type biomédicales, celui-ci sera développé sur substrat souple. Cet objectif pose certains défis quant à la maitrise des procédés de fabrication et de report des composants pour les performances des parties radiofréquences / Electronics has undergone an unquestionable evolution in recent years. The progress made gives more efficient circuits and smaller, but especially more and more energy efficient. This evolution, combined with advances in the digital and IT domain, has enabled the expansion of Internet of Things (IoT) applications based on the massive deployment of autonomous wireless communicating sensors. The first generations of sensor could only work during the time of discharge of their battery. One of the proposed ways to extend the autonomy of objects is to use the ambient energy. Several technologies have been developed to optimize the energy harvesting depending on the environment of the sensor. The work of this thesis allows developing RF energy harvesters in three steps. The first part studies antennas structures compatible with the energy harvesting. Each antenna is optimized to either recover more energy or better integrate into the environment. The second step focuses on the RF / DC conversion circuit. The study of different circuits architectures, diodes and number of stages potentially relevant for our application, allowed realising circuits able to work with our antennas. Each circuit was then optimized to increase its conversion efficiency and its sensitivity. The final step was to assemble an antenna with a rectifier to characterize the complete harvester according two different scenarios: opportunistic energy harvesting and energy transfer conditions.
6

A RECTENNA FOR 5G ENERGY HARVESTING

Efthymakis, Panagiotis 01 January 2018 (has links)
This thesis describes the design of a rectenna that is capable of operating in 5G. 5G’s availability will create the opportunity to harvest energy everywhere in the network’s coverage. This thesis investigates a Rectenna device with a new proposed topology in order to eliminate coupling between input and output lines and increase the rectification efficiency. Moreover, it is designed to charge a rechargeable battery of 3V, 1mA, with a 4.8mm diameter. The current design describes using one antenna for energy harvesting; this could be expanded to use an antenna array, which would increase the input power. This would lead to higher output currents, leading to the ability to efficiently charge a wide variety of batteries. Because of its small size, the rectenna could be used for the remote charging of an implantable sensor battery or for other applications where miniaturization is a design consideration.
7

DESIGN AND ANALYSIS OF COGNITIVE MASSIVE MIMO NETWORKS WITH UNDERLAY SPECTRUM SHARING

Al-Hraishawi, Hayder Abed Hussein 01 August 2017 (has links)
Recently, massive multiple-input multiple-output (MIMO) systems have gained significant attention as a new network architecture to not only achieving unprecedented spectral and energy efficiencies, but also to alleviating propagation losses and inter-user/inter-cell interference. Therefore, massive MIMO has been identified as one of the key candidate technologies for the 5th generation wireless standard. This dissertation thus focuses on (1) developing a performance analysis framework for cognitive massive MIMO systems by investigating the uplink transmissions of multi-cell multi-user massive MIMO secondary systems, which are underlaid in multi-cell multi-user primary massive MIMO systems, with taking into consideration the detrimental effects of practical transmission impairments, (2) proposing a new wireless-powered underlay cognitive massive MIMO system model, as the secondary user nodes is empowered by the ability to efficiently harvest energy from the primary user transmissions, and then access and utilize the primary network spectrum for information transmission, and (3) developing a secure communication strategy for cognitive multi-user massive MIMO systems, where physical layer secure transmissions are provisioned for both primary and secondary systems by exploiting linear precoders and artificial noise (AN) generation in order to degrade the signal decodability at eavesdropper. The key design feature of the proposed cognitive systems is to leverage the spatial multiplexing strategies to serve a large number of spatially distributed user nodes by using very large numbers of antennas at the base-stations. Moreover, the fundamental performance metrics, the secondary transmit power constraints, which constitute the underlay secondary transmissions subject to a predefined primary interference temperature, and the achievable sum rates of the primary and secondary systems, are characterized under different antenna array configurations. Additionally, the detrimental impact of practical wireless transmission impairments on the performance of the aforementioned systems are quantified. The important insights obtained throughout these analyses can be used as benchmarks for designing practical cognitive spectrum sharing networks.
8

Wide-Range Highly-Efficient Wireless Power Receivers for Implantable Biomedical Sensors

Ouda, Mahmoud 11 1900 (has links)
Wireless power transfer (WPT) is the key enabler for a myriad of applications, from low-power RFIDs, and wireless sensors, to wirelessly charged electric vehicles, and even massive power transmission from space solar cells. One of the major challenges in designing implantable biomedical devices is the size and lifetime of the battery. Thus, replacing the battery with a miniaturized wireless power receiver (WPRx) facilitates designing sustainable biomedical implants in smaller volumes for sentient medical applications. In the first part of this dissertation, we propose a miniaturized, fully integrated, wirelessly powered implantable sensor with on-chip antenna, designed and implemented in a standard 0.18μm CMOS process. As a batteryless device, it can be implanted once inside the body with no need for further invasive surgeries to replace batteries. The proposed single-chip solution is designed for intraocular pressure monitoring (IOPM), and can serve as a sustainable platform for implantable devices or IoT nodes. A custom setup is developed to test the chip in a saline solution with electrical properties similar to those of the aqueous humor of the eye. The proposed chip, in this eye-like setup, is wirelessly charged to 1V from a 5W transmitter 3cm away from the chip. In the second part, we propose a self-biased, differential rectifier with enhanced efficiency over an extended range of input power. A prototype is designed for the medical implant communication service (MICS) band at 433MHz. It demonstrates an efficiency improvement of more than 40% in the rectifier power conversion efficiency (PCE) and a dynamic range extension of more than 50% relative to the conventional cross-coupled rectifier. A sensitivity of -15.2dBm input power for 1V output voltage and a peak PCE of 65% are achieved for a 50k load. In the third part, we propose a wide-range, differential RF-to-DC power converter using an adaptive, self-biasing technique. The proposed architecture doubles the dynamic range of conventional rectifiers. Unlike the continuously self-biased rectifier proposed in the second part, this adaptive rectifier extends the dynamic range while maintaining both the high PCE peak and the sensitivity advantage of the conventional cross-coupled scheme, and can operates in the GHz range.
9

Nositelná rektifikační anténa pro RF sklízení energie / Wearable rectifying antenna for RF energy harvesting

Kokolia, Martin January 2016 (has links)
The aim of this thesis is to design and rectena that would be able to integrate into a cloth thanks to use of textile substrate. The first part deals with the possibilities of using various communication channels and services for maximizing the useable power. Attention is focused mainly on the use of textile materials for implementing microstrip circuits. It is made valorization of all the typical characteristics and problems using different fabrics as a microwave substrate and the possibilities of realization of conductive structures of microwave patch antenna and microstrip circuits. At the second part are identified parameters and constraints used for the design of the overall device with a rectifying antenna, which will be after the verification of the function in real implementation used for the final concept using textile structures. The design is verified by simulations by CST Microwave Studio and Microwave Designer. The initial design is being gradually extended by other concepts, the use of other materials and technologies. Several design are made, their properties evaluated and the best ones are then compared based on real measurements.
10

Towards Perpetual Energy Operation in Wireless Communication Systems

Benkhelifa, Fatma 11 1900 (has links)
Wireless is everywhere. Smartphones, tablets, laptops, implantable medical devices, and many other wireless devices are massively taking part of our everyday activities. On average, an actively digital consumer has three devices. However, most of these wireless devices are small equipped with batteries that are often limited and need to be replaced or recharged. This fact limits the operating lifetime of wireless devices and presents a major challenge in wireless communication. To improve the perpetual energy operation of wireless communication systems, energy harvesting (EH) from the radio frequency (RF) signals is one promising solution to make the wireless communication systems self-sustaining. Since RF signals are known to transmit information, it is interesting to study when RF signals are simultaneously used to transmit information and scavenge energy, namely simultaneous wireless information and power transfer (SWIPT). In this thesis, we specifically aim to study the SWIPT in multiple-input multiple-output (MIMO) relay communication systems and in cognitive radio (CR) networks. First, we study the SWIPT in MIMO relay systems where the relay harvests the energy from the source and uses partially/fully the harvested energy to forward the signal to the destination. For both the amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols, we consider the ideal scheme where both the energy and information transfer to the relay happen simultaneously, and the practical power splitting and time switching schemes. For each scheme, we aim to maximize the achievable end-to-end rate with a certain energy constraint at the relay. Furthermore, we consider the sum rate maximization problem for the multiuser MIMO DF relay broadcasting channels with multiple EH-enabled relays, and an enhanced low complex solution is proposed based on the block diagonalization method. Finally, we study the energy and data performance of the SWIPT in CR network where either the primary receiver (PR) or the secondary receiver (SR) is using the antenna switching (AS) technique. When the PR is an EH-enabled node, we illustrate the incentive of spectrum sharing in CR networks. When the SR is an EH-enabled node, we propose two thresholding-based selection schemes: the prioritizing data selection scheme and the prioritizing energy selection scheme.

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