21 research outputs found

    Introduction to Radio-frequency Identification (RFID)

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    This project presents the fundamental aspects of the RFID (Radio-frequency identifica-tion) technology used to establish wireless communications. The project focuses on thepassive mode of RFID, where the receiver does not have any power supply, which allowsits miniaturization and low cost.On the other hand, two articles from different authors are analyzed. The first consists onthe design of a very low power passive receiver through various techniques of optimizationin the hardware’s manufacture.In the second, a drone is used as an intermediate element between the transmitter and thereceiver to extend up to 10 times the typical range of passive RFID. The study focuses onthe treatment of the RF signal to considerably eliminate the interferences and to preciselylocalize the receiver.Outgoin

    2009 Index IEEE Antennas and Wireless Propagation Letters Vol. 8

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    This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

    2008 Index IEEE Transactions on Control Systems Technology Vol. 16

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    This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

    Capacitive coupled RFID tag using a new dielectric droplet encapsulation approach

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    Radio frequency identification (RFID) is a well-known and fast-growing technology used to identify people, animals and products. RFID tags are used to replace bar codes in a wide range of applications, to mention just a few, retail, transportation, logistics and healthcare. The two main driving aspects for most of research and development projects concerning RFID tags are the reduction of assembly costs and the downsizing of microchips. In that respect and considering an Industry 4.0 scenario, the study of a new assembly approach for passive and high frequency RFID tags has been proposed and studied in this thesis. In this new approach, which is based on the inkjet printing technology, a specifically designed radio frequency integrated circuit (RFIC) will be delivered, inside a liquid dielectric droplet, onto the antenna and no longer placed and oriented precisely as it happens nowadays with pick-and-place and flip chip machines. After a landing phase, the liquid droplet (with the encapsulated chip) will self-aligns with respect to the contact thanks to capillary forces driven by specifically designed wetting conditions on the substrate of the antenna. Finally, with few additional steps, the complete RFID tag is created. This research project brings to light a considerable simplification and a very high potential of parallelization, compatible with large volume manufacturing methods, in comparison to nowadays existing technologies. This may substantially drive down the fabrication costs. An in-depth analysis of electrical performances have been carefully undertaken and compliance with the ISO/IEC 144443 standard has been verified. Mathematical models have been developed showing fundamental limits for the maximum tag reading range and power requirements of the RFID reader

    Surface Acoustic Wave (saw) Cryogenic Liquid And Hydrogen Gas Sensors

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    This research was born from NASA Kennedy Space Center’s (KSC) need for passive, wireless and individually distinguishable cryogenic liquid and H2 gas sensors in various facilities. The risks of catastrophic accidents, associated with the storage and use of cryogenic fluids may be minimized by constant monitoring. Accidents involving the release of H2 gas or LH2 were responsible for 81% of total accidents in the aerospace industry. These problems may be mitigated by the implementation of a passive (or low-power), wireless, gas detection system, which continuously monitors multiple nodes and reports temperature and H2 gas presence. Passive, wireless, cryogenic liquid level and hydrogen (H2) gas sensors were developed on a platform technology called Orthogonal Frequency Coded (OFC) surface acoustic wave (SAW) radio frequency identification (RFID) tag sensors. The OFC-SAW was shown to be mechanically resistant to failure due to thermal shock from repeated cycles between room to liquid nitrogen temperature. This suggests that these tags are ideal for integration into cryogenic Dewar environments for the purposes of cryogenic liquid level detection. Three OFC-SAW H2 gas sensors were simultaneously wirelessly interrogated while being exposed to various flow rates of H2 gas. Rapid H2 detection was achieved for flow rates as low as 1ccm of a 2% H2, 98% N2 mixture. A novel method and theory to extract the electrical and mechanical properties of a semiconducting and high conductivity thin-film using SAW amplitude and velocity dispersion measurements were also developed. The SAW device was shown to be a useful tool in analysis and characterization of ultrathin and thin films and physical phenomena such as gas adsorption and desorption mechanisms

    Multi-frequency microwave energy harvesting receivers: theory and applications

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    Mención Internacional en el título de doctorEmissions across the electromagnetic spectrum are not only used for communications, but they can also be used for powering electronic devices. This resource has been made more and more abundant in the last years thanks to the recent deployment of 4G and 5G, and the popularization of broadband wireless networks such as WiFi, including traditional services such as TV and radio broadcasting. In order to take advantage of the energy (currently wasted), rectennas (a rectifier integrated with an antenna) are used. This thesis has the objective of studying these rectifying elements, to reduce or eliminate the use of batteries that are employed in millions of low-power devices and sensor networks planned for deployment in the near future. To do this, a self-supply system in situ is required. This could be achieved with photovoltaics or piezoelectrics, but they require the presence of light or vibration. However, the electromagnetic energy produced by mobile communications, TV base stations and radar is noticeable inside a large coverage area, 24 hours a day. This includes difficult access areas where it is nearly impossible to provide appropriate maintenance to replace batteries. As explained through the thesis, energy harvesting applications have a severe limitation on the available levels of power density to scavenge, constraining the RF-DC power conversion effciencies. Therefore, the amount of DC power to feed a sensor is limited and some techniques must be applied to improve the performance. This thesis proposes an alternative for improving the RF-DC power conversion efficiency based on the multiple-tone scenario (the electromagnetic spectrum). Previous studies have been published about an empirical improvement in the power efficiency when working with high Peak to Average Power Ratio (PAPR) multiple-tone signals, compared to a CW signal with the same average power, although the theoretical proof was not accurate enough. A mathematical model that predicts the expected DC current of the diode when excited with multiple tones is proposed along the thesis, having good agreement with simulations and measurements, demonstrating the good performance of the theoretical model. With this mathematical approach, convergence problems in simulation software can be avoided. This document comprises six chapters and it is organized as follows: In the first chapter a brief introduction on the evolution of wireless power transfer is presented, including all the different approaches that compose it, emphasizing the far-filed non-directional powering or harvesting, which is the topic of this thesis. In addition, an analysis of the state of the art is presented with the most signifficant values of conversion effciency, as well as the main characteristics of various designs. In the second chapter, the performance of the diode is explored theoretically. For very low incident power densities (those present in the environment), the diode works in a non-linear region, where a power effciency improvement is obtained when using high PAPR multiple-tone signal instead of a single tone with the same average power. This fact has been empirically tested but an accurate theoretical model has not been accomplished. Therefore, this chapter deals with this issue, showing a novel mathematical analysis of the diode operation in that region for multiple input tones, varying their relative amplitude and frequency. In Chapter 3, the theoretical analysis is compared with simulations and experiments for multiple input tones with a large resulting PAPR using three different rectifier circuits. To properly compare the results, it is necessary to use an accurate Spice diode model (including parasitics) and an appropriate measurement setup. Otherwise, results will differ due to an inadequate characterization of the non-linear device. This chapter addresses those issues. The analysis shows that the relative frequency and amplitude of multiple simultaneous signals impacts the amount of efficiency improvement. Once the recti er element is studied, Chapter 4 deals with the antenna design, which is part of the rectenna deployment. It is seen that different design criteria must be used when working with a WPT directive beaming application or a non-directive harvesting one, as happens in this thesis. The integration between the antenna and the recti er is analyzed, showing possible alternatives. Finally, a rectenna design is built and tested through indoor and outdoor measurements. An analysis of the electromagnetic spectrum is included to demonstrate the feasibility of the rectenna model. In Chapter 5 a wearable rectenna application is shown, with a broadband 2 to 5 GHz rectenna array, implemented on a cotton shirt. This application allows to collect enough energy to power energy-efficient devices. Different rectenna array sizes were tested at different power densities. The single element is a self-complementary tightly-coupled bow-tie. Simulations and measurements were performed over a phantom and over body tissues taking into account the electrical properties of the torso. The thickness of each layer was varied analyzing its influence in the antenna performance, to check what happens under different body compositions (people with more adipose tissue or on the contrary more brous). Finally, Chapter 6 collects the conclusions of the work shown in this thesis and ideas for future work. Some ideas are proposed about Chapter 2 to reduce the error of the mathematical approach when working in the non-linear region. Also, some possible improvements to the printed antenna of Chapter 5 are included such as adding a dual linear polarization.Las emisiones a lo largo de todo el espectro electromagnético no sólo se pueden utilizar para las comunicaciones, sino que también pueden emplearse para la alimentación de dispositivos electr onicos. Este recurso se ha hecho cada vez más abundante en los ultimos años gracias a los recientes despliegues en telefonía móvil de 4G y 5G y a la popularización de las redes inalámbricas de banda ancha (WiFi), sin olvidar las comunicaciones de difusión ya existentes como la radio o televisión. Para poder aprovechar este recurso (actualmente desaprovechado), se utilizan las llamadas rectenas, que son antenas con un elemento rectificador integrado. Esta tesis tiene por objetivo el estudio de estos elementos rectificadores, para desarrollar aplicaciones capaces de reducir o eliminar el uso de baterías en los millones de dispositivos y redes de sensores de bajo consumo existentes hoy día, mediante el autoabastecimiento de energía. Este proceso podría llevarse a cabo con paneles fotovoltaicos o sistemas piezoeléctricos, pero estos requieren de la presencia continua de la fuente que los origina (vibraciones, horas de sol). Sin embargo, la energía electromagnética producida por las estaciones base, de telefonía o televisión, está presente bajo su zona de cobertura las 24 horas del día, lo cual incluye zonas de difícil acceso, en las que es complicado el recambio o mantenimiento de las baterías. Además, estas emisiones tienen como principal limitación la baja densidad de potencia, obteniéndose valores de eficiencia de conversión RF-DC muy bajos. Esto conlleva que los valores de corriente DC para alimentar al sensor sean muy pequeños, de nA o uA, y por tanto, deben emplearse técnicas para la mejora del rendimiento. Esta tesis propone una alternativa para mejorar la eficiencia de conversión, basada en la probada mejora de eficiencia cuando se trabaja con señales con un Peak to Average Power Ratio (PAPR) grande. Esto se da en escenarios multitonales como puede ser el espectro electromagnético. Esta mejora no ha sido abordada teóricamente con resultados precisos en trabajos previos, por lo que en esta tesis se desarrolla un modelo matemático que predice la componente DC de la corriente del diodo, cuando se excita con múltiples tonos. Los resultados obtenidos han sido validados en el laboratorio, demostrándose la mejora en la eficiencia de conversión y el buen comportamiento del modelo teórico. De esta forma, se pueden agilizar los cálculos cuando no se tiene un software de simulación disponible, o cuando este arroja problemas de convergencia. Esta tesis consta de seis capítulos y está organizada de la siguiente manera: En el primer capítulo se expone una breve introducción sobre la evolución de la transferencia inalámbrica de potencia y sobre las diferentes tecnologías que la componen, haciéndose hincapié en la transferencia de potencia no directiva en campo lejano, puesto que se corresponde a la recolección de la energía electromagnética ambiental. Además, se incluye un análisis del estado del arte con los valores más significativos de eficiencia de conversión, así como las principales características de varios diseños (como por ejemplo la potencia o las bandas de trabajo empleadas). En el segundo capítulo se explora el comportamiento del diodo desde el punto de vista matemático. Bajo densidades de potencia pequeñas, como las presentes en este entorno, el diodo opera en su región no lineal, produciendo un incremento de eficiencia cuando se trabaja con señales con gran PAPR, respecto a un tono con la misma potencia media. Este hecho ha sido probado empíricamente pero ningún modelo teórico preciso ha sido realizado. En este capítulo se incluye un novedoso análisis matemático del funcionamiento del diodo en esa región para múltiples tonos de entrada, variando la amplitud y frecuencia de estos. En el capítulo 3 se muestra la comparativa entre el modelo teórico, las simulaciones y las medidas en el laboratorio, usando múltiples tonos entrada en tres rectificadores. Para comparar adecuadamente todos los resultados, es necesario utilizar un modelo Spice del diodo preciso (incluyendo los parásitos del encapsulado) y un correcto setup de medida. De lo contrario, existiría un error en los resultados debido a una caracterización inadecuada del dispositivo no lineal. Este capítulo aborda esos problemas. El análisis muestra que la frecuencia y amplitud relativa de múltiples señales simultáneas afectan a la eficiencia. Una vez estudiado el rectificador, el capítulo 4 de la tesis aborda el diseño de la antena. Para ello, se analizan los diferentes criterios de diseño que deben emplearse cuando se trabaja con una transmisión de potencia inalámbrica directiva o no directiva, como es en caso bajo estudio, así como las técnicas de integración entre rectificador y antena. Para concluir, se diseña y mide una rectena tanto en laboratorio como en espacio abierto, usando la energía ambiental, previamente caracterizada con medidas espectrales. Los resultados demuestran que es posible recolectar y rectificar la energía ambiental. En el capítulo 5 se muestra una posible aplicación al integrarse una rectena impresa en una camiseta para alimentar sensores biológicos o \wearable". Se trata de un diseño de banda ancha que opera en el rango de 2 a 5 GHz, que permite recolectar suficiente energía para alimentar sensores de bajo consumo. Se analiza el funcionamiento de dos tamaños distintos de arrays con diferentes densidades de potencia. Al ser un diseño \wearable", la aplicación ha sido diseñada y probada sobre un maniquí y un cuerpo humano, analizándose el comportamiento de la antena impresa sobre distintas composiciones corporales (personas con más tejido adiposo o por el contrario más fibrosas). Finalmente, el capítulo 6 recopila las conclusiones del trabajo que se muestra en esta tesis e ideas para trabajos futuros, proponiéndose desde enfoques para reducir más el error en la aproximación del comportamiento no lineal del diodo en el capítulo 2, a posibles mejoras en la antena impresa del capítulo 5, incluyendo la doble polarización lineal.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Carlos Martín Pascual.- Secretario: Simon Jacques Hemour.- Vocal: Nuno Miguel G. Borges De Carvalh

    Methods and tools for the design of RFICs

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    Ambient intelligence is going to focus the next advances in wireless technologies. Hence, the increasing demand on radio frequency (RF) devices and applications represents, not only a challenge for technological industries to improve its roadmaps, but also for RF engineers to design more robust, low-power, small-size and low-cost devices. Regarding to communication robustness, in the latest years, differential topologies have acquired an important relevance because of its natural noise and interference immunity. Within this framework, a differential n-port device can still be treated with the classical analysis circuit theory by means of Z-,Y-, h-parameters or the most suitable S-parameters in the radio frequency field. Despite of it, Bockelman introduced the mixed-mode scattering parameters, which more properly express the differential and common-mode behavior of symmetrical devices. Since then, such parameters have been used with a varying degree of success, as it will be shown, mainly because of a misinterpretation. Thereby, this thesis is devoted to extend the theory of mixed-mode scattering parameters and proposes the methodology to analyze such devices. For this proposal, the simplest case of a two-port device is developed. By solving this simple case, most of the lacks of the current theory are filled up. As instance, it allows the characterization and comparison of symmetric and spiral inductors, which have remained a controversy point until now. After solving this case, the theory is extended to a n-port device. Another key point on the fast and inexpensive development of radio frequency devices is the advance on fast CAD tools for the analysis and synthesis of passive devices. In the case of silicon technologies, planar inductors have become the most popular shapes because of its integrability. However, the design of inductors entails a deep experience and acknowledge not only on the behavior of such devices but on the use of electromagnetic (EM) simulators. Unfortunately, the use of EM simulators consumes an important quantity of time and resources. Thereby, this thesis is devoted to improve some of the aspects that slow down the synthesis process of inductors. Therefore, an ‘ab initio’ technique for the meshing of planar radio frequency and microwave circuits is described. The technique presented can evaluate the losses in the component with a high accuracy just in few seconds where an electromagnetic simulator would normally last hours. Likewise, a simple bisection algorithm for the synthesis of compact planar inductors is presented. It is based on a set of heuristic rules obtained from the study of the electromagnetic behavior of these planar devices. Additionally, design of a single-ended to differential low noise amplifier (LNA) in a CMOS technology is performed by using the methods and tools described.L'enginyeria de radiofreqüència i la tecnologia de microones han assolit un desenvolupament inimaginable i avui en dia formen part de la majoria de les nostres activitats diàries. Probablement, la tecnologia mòbil ha tingut un desenvolupament més ràpid que qualsevol altre avenç tecnològic de l'era digital. Avui en dia, podem dir que el paradigma de la mobilitat s'ha assolit i tenim accés ràpid a internet des de qualsevol lloc on podem estar amb un dispositiu de butxaca. No obstant això, encara hi ha fites per endavant. Es més que probable que el paradigma de l’ "ambient intelligence” sigui el centre dels pròxims avenços en les tecnologies sense fils. A diferencia del paradigma de l"ambient intelligence', l'evolució de la tecnologia de la informació mai ha tingut l'objectiu explícit de canviar la societat, sinó que ho van fer com un efecte secundari, en canvi, les visions d' “ambient intelligence” proposen expressament el transformar la societat mitjançant la connexió completa i la seva informatització. Per tant, l'augment de la demanda de dispositius de ràdio freqüència (RF) i de les seves possibles aplicacions representa, no només un repte per a les indústries tecnològiques per millorar els seus plans de treball, sinó també per als enginyers de RF que hauran de dissenyar dispositius de baixa potència, més robusts, de mida petita i de baix cost. Quant a la robustesa dels dispositius, en els últims anys, les topologies de tipus diferencial han adquirit una important rellevància per la seva immunitat natural al soroll i resistència a les interferències. Dins d'aquest marc, un dispositiu de nports diferencial, encara pot ser tractat com un dispositiu 2nx2n i la teoria clàssica d'anàlisi de circuits (és a dir, la temia de quadripols) es pot aplicar a través de paràmetres Z, Y, h o els paràmetres S, més adequats en el camp de freqüència de ràdio. Tot i això, Bockelman i Eisenstadt introdueixen els paràmetres S mixtos, que expressen més adequadament el comportament diferencial i en mode comú de dispositius simètrics o asimètrics. Des de llavors, aquests paràmetres s'han utilitzat amb un grau variable d'èxit, com es mostrarà, principalment a causa d'una mala interpretació. D'aquesta manera, la primera part d'aquesta tesi està dedicada a estendre la teoria dels paràmetres S de mode mixt i proposa la metodologia d'anàlisi d'aquest tipus de dispositius i circuits. D'aquesta forma, en el Capítol 2, es desenvolupa el cas més simple d'un dispositiu de dos ports. En resoldre aquest cas simple, la major part de les mancances de la teoria actual es posen de relleu. Com a exemple, pennet la caracterització i la comparació de bobines simètriques i espiral no simètriques, que han estat un punt de controvèrsia fins ara. Després de resoldre aquest cas, al Capítol 3 s'estén la teOIia a un dispositiu de n-ports dels quals un nombre pot ser single-ended i la resta diferencials. És en aquest moment quan la dualitat existent entre els paràmetres S estàndard i de mode mixt es pot veure clarament i es destaca en el seu conjunt. Aquesta teoria permet, tanmateix, estendre la teoria clàssica d'amplificadors quan s'analitzen per mitjà de paràmetres S. Un altre punt clau en el desenvolupament ràpid i de baix cost dels dispositius de radiofreqüència és l'avenç en les eines CAD ràpides per a l'anàlisi i síntesi dels dispositius passius, en especial dels inductors. Aquests dispositius apareixen tot sovint en el disseny de radio freqüència degut a la seva gran versatilitat. Tot i que hi ha hagut múltiples intents de reemplaçar amb components externs o circuits, fins i tot actius, en el cas de les tecnologies de silici, els inductors planars s'han convertit en les formes més populars per la seva integrabilitat. No obstant això, el disseny d'inductors implica conèixer i posseir una experiència profunda no només en el comportament d'aquests dispositius, però també en l'ús de simuladors electromagnètics (EM). Desafortunadament, l'ús dels simuladors EM consumeix una quantitat important de temps i recursos. Per tant, la síntesi dels inductors representa un important inconvenient actualment. D'aquesta manera, la segona part d'aquesta tesi està dedicada a millorar alguns dels aspectes que frenen el procés de síntesi dels inductors. Per tant, en el Capítol 4, es descriu una tècnica 'ab initio' de generació de la malla per bobines planars en ràdio freqüència i microones. La tècnica es basa en l'estudi analític dels fenòmens d'aglomeració de corrent que tenen lloc a l'interior del component. En aquesta avaluació, no es requereix una solució explícita dels corrents i de les càrregues arreu del circuit. Llavors, el nombre de cel•les de la malla assignades a una tira de metall donada, depèn del valor inicialment obtingut a partir de l'estudi analític. La tècnica presentada pot avaluar les pèrdues en el component amb una gran precisió només en uns pocs segons, quan comparat amb un simulador electromagnètic normalment es necessitaria hores. De la mateixa manera, en el Capítol 5 es presenta un senzill algoritme de bisecció per a la síntesi d'inductors planars compactes. Es basa en un conjunt de regles heurístiques obtingut a partir de l'estudi del comportament electromagnètic d'aquests dispositius planars. D'aquesta manera, el nombre d'iteracions es manté moderadament baix.D'altra banda, per tal d'accelerar l'anàlisi en cada pas, s'utilitza un simulador ràpid electromagnètic planar, el qual es basa en el coneixement que es té del component sintetitzat. Finalment, en el Capítol 6, la metodologia de paràmetres S de mode mixt proposada i les eines CAD introduides s'utilitzen àmpliament en el disseny d'un amplificador de baix soroll “single-ended” a diferencial (LNA), mitjançant una tecnologia estàndard CMOS.L'amplificador de baix soroll és un dels components claus en un sistema de recepció de radio freqüència, ja que tendeix a dominar la sensibilitat i la figura de soroll (NF) de tot el sistema. D'altra banda, les característiques d'aquest circuit estan directament relacionades amb els components actius i passius disponibles en una tecnologia donada. Per tant, la tecnologia escollida, el factor de qualitat dels passius, i la forma com es caracteritzen tindran un alt impacte en les principals figures de mèrit del circuit real

    Advanced Microwave Circuits and Systems

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    Intelligent Sensor Networks

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    In the last decade, wireless or wired sensor networks have attracted much attention. However, most designs target general sensor network issues including protocol stack (routing, MAC, etc.) and security issues. This book focuses on the close integration of sensing, networking, and smart signal processing via machine learning. Based on their world-class research, the authors present the fundamentals of intelligent sensor networks. They cover sensing and sampling, distributed signal processing, and intelligent signal learning. In addition, they present cutting-edge research results from leading experts
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