京都大学 / 新制・課程博士 / 博士(工学) / 甲第24147号 / 工博第5034号 / 新制||工||1786(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 小嶋 浩嗣, 教授 山本 衛 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

In the present thesis, I have proposed methodology of two stages Dickson charge pump, which is capable of harvesting energy at 2.45 GHz RF signal to power any low powered device. Presented design uses a simple and inexpensive circuit consisting of four microstrip patch antennas, some zero-bias Schottky diodes, Wilkinson power divider and a few passive components. Circuit was fabricated on a 60 mils RO4350B substrate (=3.66), with 1.4 mils copper conductor. Demonstration showed the charge pump provides a good performance, as it drives the low powered devices with as low as 10dBm input power at 1m away from the energy source. Thesis paper will present design techniques illustrated with data obtained on prototype circuits. The objective is to wirelessly gather energy from one RF source and convert it into usable DC power that is further applied to a set of low power electronic devices. Radio Frequency Identification (RFID) tag system could also be improved using this method. RF-to-DC conversion is accomplished by designing and characterizing an element commonly known as a Rectenna, which consists of an antenna and an associated rectification circuitry. The rectenna is fully characterized in this dissertation and is used for charging low powered devices.

In the past decade, artificial materials have attracted considerable attention as potential solutions to meet the demands of modern microwave technology for simultaneously achieving component minimization and higher performance in mobile communications, medical, and optoelectronics applications. To realize this potential, more research on metamaterials is needed. In this dissertation, new bandpass filter and diplexer as microwave metamaterial applications have been developed. Unlike the conventional complementary split ring (CSRR) filters, coupled lines are used to provide larger coupling capacitance, resulting in better bandpass characteristics with two CSRRs only. The modified bandpass filters are used to deisgn a compact diplexer. A new CSRR antenna fed by coplanar waveguide has also been developed as another metamaterial application. The rectangular shape CSRRs antenna achieves dual band frequency properties without any special matching network. The higher resonant frequency is dominantly determined by the outer slot ring, while the lower resonant frequency is generated by the coupling between two CSRRs. The proposed antenna achieves about 35 percent size reduction, compared with the conventional slot antennas at the low resonant frequencies. As a future alternative energy solution, space solar power transmission and wireless power transmission have received much attention. The design of efficient rectifying antennas called rectennas is very critical in the wireless power transmission system. The conventional method to obtain long distance range and high output power is to use a large antenna array in rectenna design. However, the use of array antennas has several problems: the relatively high loss of the array feed networks, difficultiy in feeding network design, and antenna radiator coupling that degrades rectenna array performance. In this dissertation, to overcome the above problems, a reflectarray is used to build a rectenna system. The spatial feeding method of the reflectarray eliminates the energy loss and design complexity of a feeding network. A high gain rectifying antenna has been developed and located at the focal point of the reflectarray to receive the reflected RF singals and genterate DC power. The technologies are very useful for high power wireless power transmission applications.

ABSTRACT Control of spectral thermal emission from surfaces may be desirable in some energy related applications, such as nano-scale antenna energy conversion and thermophotovoltaic conversion. There are a number of methods, from commercially available paints to advanced surface gratings that can be used to modify the thermal emission from a surface. To find out the proper emission controlling technique for a given energy conversion method all the surface emission controlling methods are comprehensively reviewed regarding the emission control capabilities and the range of possible applications. Radiation with high degree of coherence can be emitted using advanced surface emission controlling techniques. The entropy of the thermal radiation, and therefore the exergy, is a function of the degree of coherence. A methodology is presented to calculate the exergy of partially coherent wave fields so that the radiation fields can be evaluated based on exergy. This exergy method is extended to develop a rigorous evaluation criterion for thermal emission controlling methods used in frequency dependent energy conversion applications. To demonstrate these developed criteria using actual data, a surface plasmon emitter is designed and fabricated. Also, possible ways of improving the emitter performance and the research needed to be carryout to fabricate cost effective emitters are described.

In this study, we explore ultra-thin insulators of organic and inorganic composition and their potential role as high-speed rectifiers. Typical applications for these structures include IR sensing, chemical detection, high speed logic circuits, and MEMS enhancements. While there are many elements in the functional group required to create a rectifying antenna (rectenna), the primary thrust of this work is on the rectifier element itself. To achieve these research goals, a very good understanding of quantum tunneling was required to model the underlying phenomenon of charge conduction. The development of a multi-variable optimization routine for tunneling prediction was required. MATLAB was selected as the programming language for this application because of its flexibility and relative ease of use for simulation purposes. Modeling of physical processes, control of electromechanical systems, and simulation of ion implantation were also to be undertaken. To advance the process science, a lithographic mask set was made which utilized the information gleaned from the theoretical simulations and initial basic experiments to create a number of diode test structures. This came to include the creation of generations of mask sets--each optimizing various parameters including testability, alignment, contact area, device density, and process ease. Following this work, a complete toolset for the creation of "soft" contact top metals was required and needed to be developed. Ultra-flat substrates were needed to improve device reliability and measurement consistency. The final phase of research included measurement and characterization of the resultant structures. Basic DC electrical characterization of the organic monolayers would be accomplished using metal probes. Statistical studies of reliability and process yield could then easily be carried out. The rectification ratio (ratio of forward over reverse current at a given voltage magnitude) was found to be a reliable indicator of diode performance in the low frequency ranges. This would mean writing additional code in MATLAB to assist in the automatic analysis for the acquired IV curves. Progression to AC / RF measurements of tunneling performance was to be accomplished using relatively low frequencies (below 100 MHz). Finally, the organic films themselves would be studied for consistency, impedance characteristics, incidence of defects, and thickness by a variety of metrology techniques. This project resulted in a number of advances to the state-of-the-art in nanofabrication using organic monolayers. A very detailed review of the state of alkanethiol research was presented and submitted for publication. A single pot technique was developed to softly deposit metal nanoparticles onto a charged surface with a high degree of control. A temporary contact method using pure, sub-cooled gallium liquid metal was used to probe organic monolayers and plot IV curves with better understanding of surface states than before. An inkjet printer solution was devised for top contact printing which involved the development and production of a work-up free insulator ink which is water soluble and printable to resolutions of about 25 um. Localized selective chemical crosslinking was found to reduce printed ink solubility following deposition. Future work will likely include additional exploration of crosslinkable Langmuir-Blodgett films as MIM insulators. Stability and testing will hinge on the fabrication of enclosures or packages for environmental isolation.

La transmission d'énergie sans fils (TESF) a été initiée dans les années soixante afin de répondre à des préoccupations énergétiques de tout premier ordre. Un demi-siècle plus tard, la question énergétique reste une préoccupation majeure qui ne se pose plus uniquement en termes de ressources mais également en termes d'autonomie et de portabilité. La TESF s'est adaptée à cette situation et est actuellement orientée vers le développement de structures capables de convertir des densités de puissance faibles afin d'améliorer l'autonomie des systèmes électroniques portables ou d'alimenter à distance des dispositifs électroniques inaccessibles ou nomades.Le travail proposé est subdivisé en trois parties : une première partie qui traite de la conversion de puissances faibles et qui présente un circuit rectenna (rectifying antenna) mono-diode fonctionnant sur une gamme de puissance allant de 1 mW à 10 mW. Une seconde partie, traitant de la conversion de puissances importantes, basée sur un convertisseur en pont de diodes capable de convertir des puissances allant jusqu'à 200 mW, et une dernière partie dédiée à l'élévation de la puissance transmise à la charge au travers d'associations de rectenna dont nous présentons plusieurs variantes.La comparaison technologique est à la base de ce travail. En effet, les développements récents des composants CMS permettent aujourd'hui de les utiliser pour la réalisation de circuits RF fonctionnant à des fréquences allant jusqu'à plusieurs gigahertz. Nous proposons dans cette thèse plusieurs circuits basés sur cette technologie que nous comparons à une technologie intégrée qui s'impose comme une alternative aux circuits micro-rubans. Ce travail a également été l'occasion d'introduire certains principes de l'électronique de puissance dans la conception de circuits RF.

In the present thesis, I have proposed methodology of two stages Dickson charge pump, which is capable of harvesting energy at 2.45 GHz RF signal to power any low powered device. Presented design uses a simple and inexpensive circuit consisting of four microstrip patch antennas, some zero-bias Schottky diodes, Wilkinson power divider and a few passive components. Circuit was fabricated on a 60 mils RO4350B substrate (=3.66), with 1.4 mils copper conductor. Demonstration showed the charge pump provides a good performance, as it drives the low powered devices with as low as 10dBm input power at 1m away from the energy source. Thesis paper will present design techniques illustrated with data obtained on prototype circuits. The objective is to wirelessly gather energy from one RF source and convert it into usable DC power that is further applied to a set of low power electronic devices. Radio Frequency Identification (RFID) tag system could also be improved using this method. RF-to-DC conversion is accomplished by designing and characterizing an element commonly known as a Rectenna, which consists of an antenna and an associated rectification circuitry. The rectenna is fully characterized in this dissertation and is used for charging low powered devices.

Les dispositifs électroniques modernes comportent souvent une ou plusieurs phases de veille, dans lesquelles elles attendent un ordre de réveil de la part d'un actionneur distant (une télécommande). Ces types de dispositifs ont tendance à être de plus en plus présents dans les habitations et dans les bâtiments tertiaires, en particulier dans le domaine de la domotique. Les phases de veille sont caractérisées par des niveaux de consommations très inférieures aux consommations en mode actif des dispositifs, mais les durées de veille sont généralement grandes devant les périodes actives. Ce fait, combiné à la multiplication des dispositifs, mène à des consommations annuelles qui peuvent dépasser 10 % de la facture d'électricité des ménages. Cette étude propose une nouvelle approche de réveil des dispositifs en veille. Au lieu d'avoir une écoute permanente en réception et d'envoyer une trame d'informations de réveil, le récepteur est complètement endormi et est réveillé à travers une impulsion d'énergie transmis par d'ondes électromagnétiques. Une fois que l'étage d'interprétation des données est alimenté, un envoi d'informations est effectué pour valider l'ordre de réveil. En vue des portées attendues pour le système et des contraintes normatives liées aux expositions des personnes aux champs électromagnétiques, une faible quantité d'énergie est disponible en réception pour le réveil du dispositif. Plusieurs topologies de circuits de rectification RF-DC (rectenna) en technologies microstrip sont étudiées à travers des simulations circuit et électromagnétiques. La topologie choisie a été optimisée pour fournir un bon niveau de tension DC pour des faibles niveaux de puissance RF incidente. Une adaptation entre le convertisseur et l'antenne de réception différente de 50 W a été utilisée. Tous ces résultats ont été validés expérimentalement. Au niveau du circuit de réception des données, plusieurs scénarios de fonctionnement ont été comparés. L'étage de démodulation utilise la rectenna comme détecteur à diodes, pour réduire au maximum la consommation et la complexité de mise en œuvre. Le système global a été testé et des gains substantiels sont constatés sur le bilan de consommation annuelle de plusieurs types des dispositifs, comparé à un fonctionnement classique. En parallèle, une architecture de récepteur d'énergie électromagnétique reconfigurable est proposée. Il offre l'avantage de pouvoir exploiter une large gamme de puissance incidente, ce qui n'est pas le cas des structures de rectennas classiques. Des rectennas en technologies discrètes et intégrées sont utilisées, connectées à une antenne commune à travers un switch d'antenne intégrée. Le système proposé est adaptatif et les résultats des tests montrent des améliorations notables de la quantité d'énergie collectée par rapport à des rectennas individuelles. Enfin, le phénomène de l'inversion de la tension dans une association déséquilibrée de rectennas est mis en évidence et des solutions sont proposées.

Various nondestructive testing (NDT) technologies for construction and performance monitoring have been studied for decades. Recently, the rapid evolution of wireless sensor network (WSN) technologies has enabled the development of sensors that can be embedded in concrete to monitor the structural health of infrastructure. Such sensors can be buried inside concrete and they can collect and report valuable volumetric data related to the health of a structure during and/or after construction. Wireless embedded sensors monitoring system is also a promising solution for decreasing the high installation and maintenance cost of the conventional wire based monitoring systems. Wireless monitoring sensors need to operate for long time. However, sensor batteries have finite life-time. Therefore, in order to enable long operational life of wireless sensors, novel wireless powering methods, which can charge the sensors’ rechargeable batteries wirelessly, need to be developed. The optimization of RF wireless powering of sensors embedded in concrete is studied here. First, our analytical results focus on calculating the transmission loss and propagation loss of electromagnetic waves penetrating into plain concrete at different humidity conditions for various frequencies. This analysis specifically leads to the identification of an optimum frequency range within 20-80 MHz that is validated through full-wave electromagnetic simulations. Second, the effects of various reinforced bar configurations on the efficiency of wireless powering are investigated. Specifically, effects of the following factors are studied: rebar types, rebar period, rebar radius, depth inside concrete, and offset placement. This analysis leads to the identification of the 902-928 MHz ISM band as the optimum power transmission frequency range for sensors embedded in reinforced concrete, since antennas working in this band are less sensitive to the effects of varying humidity as well as rebar configurations. Finally, optimized rectennas are designed for receiving and/or harvesting power in order to charge the rechargeable batteries of the embedded sensors. Such optimized wireless powering systems exhibit significantly larger efficiencies than the efficiencies of conventional RF wireless powering systems for sensors embedded in plain or reinforced concrete.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22658号 / 工博第4742号 / 新制||工||1741(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 守倉 正博, 教授 小嶋 浩嗣 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM