Esta dissertação apresenta um estudo que teve por finalidade desenvolver uma solução alternativa para reduzir a intermodulação entre antenas de leitores utilizados em sistemas RFID (Radio Frequency Identification), por esta razão, foi realizada uma pesquisa que consistiu em uma revisão sistemática sobre interferência entre antenas de leitores RFID. Os resultados mostraram que 70% das publicações analisadas foram realizadas em apenas cinco países e que 49% foram publicadas nos últimos três anos. A revisão sistemática também identificou que existem modelos que classificam as técnicas utilizadas para redução da interferenciaentre leitores, porém nenhuma das pesquisas analisadas apresentou uma sintese de classificação que contemplasse todas a técnicas de intermodulação citadas nas pesquisas, o que resultou no desenvolvimento de uma sintese de classificação de intermodulação oriunda de sistemas RFID A revisão identificou que 27% das formas de redução de intermodulação entre antenas manipulava a potência de saída do leitor para redução da área afetada pelas antenas como forma de evitar a intermodulação, porém nenhuma pesquisa propôs realizar alguma modificação nas características das antenas de forma a evitar a interferência ocorrida entre leitores. Esse fato motivou o desenvolvimento de uma antena para a faixa de frequência UHF (Ultra High Frequency) destinada a sistemas RFID com diagrama de radiação ajustável em ambientes de produção. A pesquisa foi desenvolvida com base nos princípios metodológicos de um Modelo para P&D (Pesquisa e Desenvolvimento) para produtos eletrônicos por pequenas equipes, engenheiros independentes e inventores. Como resultado foi obtido um protótipo que foi comparado com antenas comerciais para demonstrar a possibilidade de alterar o lóbulo de radiação. A nova antena desenvolvida também possui um diferencial, que reside na opção de ser utilizada tanto como antena direcional quanto omnidirecional, bastando apenas modificar a configuração de instalação. / This dissertation presents a study that aimed to develop an alternative solution for reducing intermodulation between readers antennas used in RFID systems (Radio Frequency Identification), for this reason, a survey that consisted of a systematic review of interference was carried out between antennas RFID readers. The results showed that 70% of the analyzed publications were performed in only five countries and that 49% have been published in the last three years. The systematic review also found that there are models that classify the techniques used to reduce interferenciaentre readers, but none of the studies analyzed showed a synthesis of classification system encompassing all the intermodulation techniques cited in the research, which resulted in the development of a classification synthesis intermodulation coming from RFID systems. A review showed that 27% of forms of intermodulation reduction between antenna manipulating the reader's output power to reduce the area affected by the antennas in order to avoid intermodulation, but no research proposed to carry some modification in the characteristics of antennas in order to avoid interference occurred between readers. This fact motivated the development of an antenna for the UHF band (ultra high frequency) RFID systems designed with adjustable radiation pattern in production environments. The research was developed based on methodological principles of a model for R & D (Research and Development) for electronic products in small teams, independent engineers and inventors. The result was a prototype which was compared with commercial antennas to demonstrate the ability to change the radiation lobe. The new antenna developed also has a differential, which lies in the option to be used both as directional as omnidirectional antenna by simply modifying the installation configuration.

Dissertation (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 160-167).

Esta dissertação apresenta um estudo que teve por finalidade desenvolver uma solução alternativa para reduzir a intermodulação entre antenas de leitores utilizados em sistemas RFID (Radio Frequency Identification), por esta razão, foi realizada uma pesquisa que consistiu em uma revisão sistemática sobre interferência entre antenas de leitores RFID. Os resultados mostraram que 70% das publicações analisadas foram realizadas em apenas cinco países e que 49% foram publicadas nos últimos três anos. A revisão sistemática também identificou que existem modelos que classificam as técnicas utilizadas para redução da interferenciaentre leitores, porém nenhuma das pesquisas analisadas apresentou uma sintese de classificação que contemplasse todas a técnicas de intermodulação citadas nas pesquisas, o que resultou no desenvolvimento de uma sintese de classificação de intermodulação oriunda de sistemas RFID A revisão identificou que 27% das formas de redução de intermodulação entre antenas manipulava a potência de saída do leitor para redução da área afetada pelas antenas como forma de evitar a intermodulação, porém nenhuma pesquisa propôs realizar alguma modificação nas características das antenas de forma a evitar a interferência ocorrida entre leitores. Esse fato motivou o desenvolvimento de uma antena para a faixa de frequência UHF (Ultra High Frequency) destinada a sistemas RFID com diagrama de radiação ajustável em ambientes de produção. A pesquisa foi desenvolvida com base nos princípios metodológicos de um Modelo para P&D (Pesquisa e Desenvolvimento) para produtos eletrônicos por pequenas equipes, engenheiros independentes e inventores. Como resultado foi obtido um protótipo que foi comparado com antenas comerciais para demonstrar a possibilidade de alterar o lóbulo de radiação. A nova antena desenvolvida também possui um diferencial, que reside na opção de ser utilizada tanto como antena direcional quanto omnidirecional, bastando apenas modificar a configuração de instalação. / This dissertation presents a study that aimed to develop an alternative solution for reducing intermodulation between readers antennas used in RFID systems (Radio Frequency Identification), for this reason, a survey that consisted of a systematic review of interference was carried out between antennas RFID readers. The results showed that 70% of the analyzed publications were performed in only five countries and that 49% have been published in the last three years. The systematic review also found that there are models that classify the techniques used to reduce interferenciaentre readers, but none of the studies analyzed showed a synthesis of classification system encompassing all the intermodulation techniques cited in the research, which resulted in the development of a classification synthesis intermodulation coming from RFID systems. A review showed that 27% of forms of intermodulation reduction between antenna manipulating the reader's output power to reduce the area affected by the antennas in order to avoid intermodulation, but no research proposed to carry some modification in the characteristics of antennas in order to avoid interference occurred between readers. This fact motivated the development of an antenna for the UHF band (ultra high frequency) RFID systems designed with adjustable radiation pattern in production environments. The research was developed based on methodological principles of a model for R & D (Research and Development) for electronic products in small teams, independent engineers and inventors. The result was a prototype which was compared with commercial antennas to demonstrate the ability to change the radiation lobe. The new antenna developed also has a differential, which lies in the option to be used both as directional as omnidirectional antenna by simply modifying the installation configuration.

Esta dissertação apresenta um estudo que teve por finalidade desenvolver uma solução alternativa para reduzir a intermodulação entre antenas de leitores utilizados em sistemas RFID (Radio Frequency Identification), por esta razão, foi realizada uma pesquisa que consistiu em uma revisão sistemática sobre interferência entre antenas de leitores RFID. Os resultados mostraram que 70% das publicações analisadas foram realizadas em apenas cinco países e que 49% foram publicadas nos últimos três anos. A revisão sistemática também identificou que existem modelos que classificam as técnicas utilizadas para redução da interferenciaentre leitores, porém nenhuma das pesquisas analisadas apresentou uma sintese de classificação que contemplasse todas a técnicas de intermodulação citadas nas pesquisas, o que resultou no desenvolvimento de uma sintese de classificação de intermodulação oriunda de sistemas RFID A revisão identificou que 27% das formas de redução de intermodulação entre antenas manipulava a potência de saída do leitor para redução da área afetada pelas antenas como forma de evitar a intermodulação, porém nenhuma pesquisa propôs realizar alguma modificação nas características das antenas de forma a evitar a interferência ocorrida entre leitores. Esse fato motivou o desenvolvimento de uma antena para a faixa de frequência UHF (Ultra High Frequency) destinada a sistemas RFID com diagrama de radiação ajustável em ambientes de produção. A pesquisa foi desenvolvida com base nos princípios metodológicos de um Modelo para P&D (Pesquisa e Desenvolvimento) para produtos eletrônicos por pequenas equipes, engenheiros independentes e inventores. Como resultado foi obtido um protótipo que foi comparado com antenas comerciais para demonstrar a possibilidade de alterar o lóbulo de radiação. A nova antena desenvolvida também possui um diferencial, que reside na opção de ser utilizada tanto como antena direcional quanto omnidirecional, bastando apenas modificar a configuração de instalação. / This dissertation presents a study that aimed to develop an alternative solution for reducing intermodulation between readers antennas used in RFID systems (Radio Frequency Identification), for this reason, a survey that consisted of a systematic review of interference was carried out between antennas RFID readers. The results showed that 70% of the analyzed publications were performed in only five countries and that 49% have been published in the last three years. The systematic review also found that there are models that classify the techniques used to reduce interferenciaentre readers, but none of the studies analyzed showed a synthesis of classification system encompassing all the intermodulation techniques cited in the research, which resulted in the development of a classification synthesis intermodulation coming from RFID systems. A review showed that 27% of forms of intermodulation reduction between antenna manipulating the reader's output power to reduce the area affected by the antennas in order to avoid intermodulation, but no research proposed to carry some modification in the characteristics of antennas in order to avoid interference occurred between readers. This fact motivated the development of an antenna for the UHF band (ultra high frequency) RFID systems designed with adjustable radiation pattern in production environments. The research was developed based on methodological principles of a model for R & D (Research and Development) for electronic products in small teams, independent engineers and inventors. The result was a prototype which was compared with commercial antennas to demonstrate the ability to change the radiation lobe. The new antenna developed also has a differential, which lies in the option to be used both as directional as omnidirectional antenna by simply modifying the installation configuration.

[pt] A representação de várias portadoras SCPC/ FM contiguas por uma banda de ruído não permite obter com exatidão a densidade espectral de potência de intermodulação na saída de uma amplificador não-linear. No entanto, este trabalho mostra que, usada adequadamente, a representação por uma banda de ruído oferece uma solução para o problema de determinação dos efeitos da intermodução, na medida em que permite calcular com grande precisão a potência de intermodulação em RF dentro da faixa de qualquer portadora, o ruído em banda básica pode ser calculado de maneira adequada. Um programa de computador utilizando essa técnica para transponders ocupados por portadoras SCPC/ FM de diferentes níveis foi desenvolvido e como validação do procedimento proposto foram feitas comparações com os resultados obtidos a partir de uma técnica de contagem rápida de produtos de intermodulação recentemente desenvolvida. A representação por bandas de ruído é também útil quando portadoras com diferentes densidades espectrais de potência normalizadas compõem o transponder. / [en] Replacing several contiguous SCPC/ FM carriers by na equivalent band of thermal noise does not lead to the exact intermodulation power spectral density at the output of a nonlinear amplifier. However, this work shows that an appropriate use of the results following from this approach can still lead to a solution for the problem of evaluating intermodulation impairments, since a precise computation of the RF intermodulation power inside the frequency bandwidth of any carrier is indeed performed. Furthermore, if the spectrum shape is taken into account the baseband noise can be found in a proper way. A computer program using this technique for transponders accessed by SCPC/ FM carriers of different levels has been developed. In order to validate the proposed procedure, comparisons have been performed with the results based on another recently developed technique, involving a fast algorithm for counting intermodulation products. Replacing contiguous narrow-band carriers by thermal noise is also useful when carriers with different normalized power spectral densities are accessing the transponder.

L'évolution des télécommunications a fait des produits d'intermodulation passive (PIM) un critère de qualité et de performance du réseau mais également un problème de premier ordre pour les fournisseurs de services comme par exemple les opérateurs de téléphonie mobile. Les travaux présentés dans ce manuscrit constituent une contribution à la résolution d'une partie des problèmes de PIM dans les antennes de station de base et s'articulent autour de trois axes principaux : - la caractérisation des sources d'intermodulation passive au sein des antennes de station de base. De nombreuses études expérimentales ont été réalisées avec l'objectif de déterminer l'influence de différents paramètres sur la PIM générée par les contacts métal-métal (rugosité des surfaces, utilisation de traitement de surface, géométrie et nature des métaux) ou par les circuits imprimés de type micro-ruban (adaptation, largeur de ligne et épaisseur du substrat diélectrique). Les résultats de ces études ont permis d'améliorer les connaissances théoriques et de définir des règles permettant de réduire les niveaux de PIM induits ; - la localisation des sources d'intermodulation passive au sein de systèmes radiofréquences complexes. Pour cela, un banc de mesure PIM spécifique a été conçu. Celui-ci permet de localiser des sources de PIM, de niveau proche de la spécification 3GPP, avec une précision inférieure à 2cm. De plus, pour faciliter la détection des défauts PIM dans une antenne de station de base, différentes méthodes complémentaires ont été développées et associées à ce banc de mesure ; - la modélisation, à partir des résultats des études expérimentales réalisées, de composants non-linéaires intégrables à un simulateur de type circuit. L'utilisation de ces derniers permet aux ingénieurs d'estimer, dès la phase de conception, le comportement PIM des contacts métal-métal et des circuits imprimés de type micro-ruban et tri-plaque suspendue. / The evolution of telecommunications has made passive intermodulation products (PIM) not only a criterion of quality and network performance but also a major problem for service providers such as mobile operators. The work presented in this manuscript is a contribution to the resolution of some of PIM problems in base station antennas and is organized around three main axes : - the characterization of passive intermodulation root causes within base station antennas. Numerous experimental studies have been carried out with the aim of determining the influence of different parameters on the PIM generated by metal-to-metal contacts (roughness of surfaces, use of surface treatment, geometry and nature of metals) or by printed circuits as microstrip type (matching, line width and thickness of dielectric substrate). The results of these studies contributed to improve theoretical knowledge and to define rules to reduce induced PIM levels ; - the localization of passive intermodulation root causes within complex radio frequency systems. For this, a specific PIM measurements bench has been designed. It allows locating PIM root causes, with a level close to the current 3GPP specification, with an accuracy less than 2cm. In addition, to ease the PIM defects detection in a base station antenna, various complementary methods have been developed and associated with the measurements bench ; - the electromagnetic modeling issued from the experimental studies, carried out of non-linear components usable into a circuit-type simulator. The use of these allows designers to estimate, early during the design stage, the PIM behavior of metal-to-metal contacts, microstrip and suspended stripline printed circuits.

Électromagnétisme, sécurité et guerre électronique sont étroitement liés depuis des décennies. Leur association rassemble des applications de surveillance radar, de neutralisation de systèmes électroniques ou de détection d’électroniques cachées. Aujourd’hui, la multiplication des EEI (Engins Explosifs Improvisés) aussi bien sur les théâtres d’opération que dans les milieux urbains conduit à la nécessité de leur détection. Les travaux de cette thèse peuvent entrer dans cette thématique et proposent une nouvelle alternative qui permet de mettre en évidence la présence de récepteurs RF cachés. Le radar non-linéaire est particulièrement adapté à la détection de dispositifs contenant des métaux et des semi-conducteurs (électroniques). Une technique populaire consiste à transmettre une seule fréquence f1 et à recevoir la seconde harmonique générée par la cible. Une autre technique, moins courante, consiste à transmettre deux fréquences, f1 et f2, et à recevoir les produits d'intermodulation d’ordre 3 (2f1 - f2 et 2f2 - f1). Un état de l’art approfondi des systèmes radars non-linéaires est effectué dans un premier chapitre avec une comparaison de leurs caractéristiques. Dans un second chapitre, un banc de test en mode conduit est développé permettant la mesure de l’IM3 réfléchi d’une cible RF. Ainsi des analyses et des ordres de grandeurs seront connus aidant au développement du radar. Dans le chapitre 3, Le démonstrateur du radar à IM3 est développé. Un large panel de systèmes RF, commerciaux ou non, susceptibles d’être trouvé dans des milieux opérationnels est mis sous test. Leur détection va permettre de valider la technique de récupération de l’IM3. Un nouveau bilan de liaison réaliste du radar IM3 est mis en place afin d’estimer la portée de détection réelle du radar, pour différentes cibles RF. Dans le dernier chapitre les travaux s’orientent sur l’identification et la classification d’une cible RF. L’étude porte sur la possibilité d’extraire tous paramètres pouvant aider à une classification (évaluation du danger) de récepteurs RF dans un milieu opérationnel. Le travail de recherche présenté dans ce manuscrit contribue à l’amélioration des techniques de détection d’électroniques cachées. Un protocole de détection a été proposé décrivant les faits et gestes du radar IM3. Il inclut un balayage en fréquence puis en puissance. Les premiers tests ont été effectués sur un Talkie-Walkie démontrant la possibilité de détecter sa bande passante via la réémission d’IM3, à plus de 2 m. La répétabilité des tests sur un panel élargi de récepteurs RF valide le protocole de détection et l’intérêt du radar IM3. Une puissance d’émission du radar IM3 de 40 dBm, à une fréquence d’IM3 de 400 MHz, peut potentiellement détecter un récepteur à 80 m. Enfin dans un dernier travail exploratoire nous avons démontré que, par l’observation de la réponse de l’IM3 réfléchi suite à un balayage en puissance, le radar IM3 peut ajouter de nouveaux critères d’identification discriminant les récepteurs détectés entre eux. / Electromagnetism, security and electronic warfare have been closely linked for decades. Their association gathers applications of radar surveillance, neutralization of electronic systems or detection of hidden electronics. Today, the multiplication of IEDs (Improvised Explosive Devices) both in theatres of operation and in urban environments leads to the need for their detection. The works of this thesis can enter into this theme and propose a new alternative that allows to highlight the presence of hidden RF receivers. The nonlinear radar is particularly suitable for detecting devices containing metals and (electronic) semiconductors. A popular technique is to transmit a single frequency f1 and receive the second harmonic generated by the target. Another less common technique consists of transmitting two frequencies, f1 and f2, and receiving intermodulation products of order 3 (2f1 - f2 and 2f2 - f1). An in-depth state of the art of nonlinear radar systems is made in a first chapter with a comparison of their characteristics. In a second chapter, an inductive test bench is developed to measure the reflected IM3 of an RF target. Thus analyses and orders of magnitude will be known helping the development of radar. In chapter 3, the IM3 radar demonstrator is developed. A wide range of RF systems, commercial and non-commercial, that may be found in operational environments are being tested. Their detection will validate the IM3 recovery technique. A new realistic IM3 radar link budget is implemented to estimate the actual radar detection range for different RF targets. In the last chapter the work focuses on the identification and classification of an RF target. The study focuses on the possibility of extracting all parameters to assist in a classification (hazard assessment) of RF receptors in an operational environment. The research work presented in this manuscript contributes to the improvement of hidden electronic detection techniques. A detection protocol was proposed describing the actions of the IM3 radar. It includes a frequency scan and then a power scan. The first tests were carried out on a walkie-talkie demonstrating the possibility of detecting its bandwidth via IM3 retransmission, at more than 2 m. The repeatability of the tests on an extended panel of RF receivers validates the detection protocol and the interest of the IM3 radar. An IM3 radar transmission power of 40 dBm, at an IM3 frequency of 400 MHz, can potentially detect a receiver at 80 m. Finally in a final exploratory work, we demonstrated that by observing the IM3 response reflected following a power scan the IM3 radar can add new identification criteria that discriminate the hidden receivers detected between them.

Ce mémoire présente la conception, la réalisation et la caractérisation d'un micro-haut-parleur en silicium destiné à des applications électroniques portables, telles que les tablettes et les téléphones cellulaires. L'objectif est d'évaluer le potentiel des microtechnologies pour améliorer la qualité sonore et le rendement électroacoustique, qui sont deux points faibles majeurs des micro-haut-parleurs actuels.En analysant les paramètres dont dépendent le rendement et la qualité sonore, nous montrons que le silicium monocristallin présente des propriétés particulièrement intéressantes pour réaliser la surface émissive et la suspension du transducteur. Une microstructure de la partie mobile est proposée pour satisfaire la double exigence d'une surface émissive très rigide, nécessaire à la qualité sonore, et d'une masse très faible, permettant d'augmenter le rendement. Les aimants et la bobine, qui constituent le moteur électrodynamique, sont également optimisés en utilisant conjointement des modèles analytiques et à éléments finis. La microfabrication du transducteur MEMS est étudiée, étape par étape. Elle repose sur l'utilisation d'un substrat SOI (silicium sur isolant), qui sert de base à la structuration des différents composants, et sur lequel sont rapportés des aimants massifs. La caractérisation électroacoustique des échantillons réalisés montre une très bonne qualité de reproduction sonore. Un niveau sonore de 80 dB à 10 cm est obtenu pour une puissance électrique de 0,5 W, ce qui place le rendement au niveau des micro-haut-parleurs du marché. Ces travaux montrent en outre que les technologies MEMS offrent des possibilités d'augmenter très largement le rendement. / This research work presents the conception, the development, and the characterization of a silicon-based microspeaker for portable electronic device applications, such as tablets and cellular phones. The objective is to investigate the potential of microsystem technologies with the goal of improving the sound quality and the electroacoustic efficiency, which are two main drawbacks of the today’s microspeakers.By analyzing various parameters which influence the efficiency and the sound quality, we show that the monocrystalline silicon has very interesting mechanical properties which make it the proper choice to be deployed for the membrane as well as the suspension of the transducer.A stiffening structure is proposed to satisfy both the rigidity and the lightness of the membrane, for the sake of sound quality and high efficiency respectively. The magnets and the coil, which compose the electromagnetic motor of the device, are also optimized with the help of analytical and finite element models.Afterwards, the microfabrication of the MEMS microspeaker is studied step by step. It is indeed based on a SOI (silicon on insulator) substrate which makes possible the micromachining of the different parts and the assembly of bulk permanent magnets. The electroacoustic characterization of the MEMS microspeaker samples shows a very high sound quality. A sound pressure level of 80 dB at 10 cm is measured for an electrical power of 0.5 W. This classifies the MEMS microspeaker’s efficiency among that of today’s non-MEMS microspeakers.This work presents, moreover, the possibility of increasing even more the efficiency thanks to the MEMS technology.

Photoconductive microwave switches can be used in place of traditional microwave switches to reconfigure antennas and RF circuits. The switch, which consists of a silicon die placed over a gap in transmission line, is controlled by illumination via a fibre optic cable. Hence there is no requirement to design electrical biasing lines which may affect RF performance. This benefit is the main motivation behind further developing and understanding the photoconductive switch. The second motivation is the growing demand for reconfigurable antennas which necessitate certain switching requirements; one specific area of interest is in cognitive radio applications. However, in order to use such a switch in RF circuitry, the photoconductive nature of the switch must be understood. This is addressed in this thesis presenting and applying analytical equations which dictate the material properties in photoconductive silicon. These equations are then used to generate a 3D EM simulation model to investigate transmission loss in the photoconductive switch. The concept of signal planarity is investigated so as to give some insight into the best way to package the switch. In order to potentially reduce loss and facilitate a packaged device, the fabrication of the switch is investigated. Namely, the treatment of the silicon and the addition of contacts on the silicon are discussed as possible methods to improve switch performance. Lastly, linearity, power handing and switching times are presented for the photoconductive switch. This characterisation is important with regards to understanding which types of application the switch can be used in. In particular the single tone and two tone linearity of the switch is measured these values have not previously been reported for this type of photoconductive switch. The results are encouraging and support further development of the switch into a packaged product to be used in reconfigurable antennas and circuitry.