La télémétrie biomédicale et l’interfaçage neuronal à base de dispositifs miniatures et autonomes sans fil constituent de nouvelles applications en émergence. Elles visent à répondre à de nombreux enjeux y compris dans les domaines de la santé, du sport et bien être, ou encore de la sécurité au travail et de la défense. Parmi les applications typiques de biotélémétrie, nous pouvons citer le monitoring de certains paramètres physiologiques : température corporelle, pression artérielle, rythme cardiaque, taux de glucose et d’anticorps, détection d’agents chimiques, etc. En ce qui concerne l’interfaçage neuronal, il permet de restaurer les informations sensorielles, d’aider à la réadaptation des amputés, des personnes atteintes de paralysie ou des patients atteints de maladies neurodégénératives. L’objectif principal de cette thèse est de contribuer au développement de dispositifs miniaturisés et communicants pour le monitoring, en continu, de variables physiologiques d’humains ainsi que d’animaux. Ces dispositifs innovants nécessitent un système de communication fiable. Plus particulièrement, il s’agit d’analyser le milieu de propagation à l’intérieur des tissus biologiques et de développer des antennes miniatures innovantes ainsi que des méthodes pour leur analyse et leur caractérisation. Le verrou majeur concerne le rendement des antennes miniatures. Les effets de forte hétérogénéité, dispersion, pertes très élevées des milieux biologiques et les contraintes de miniaturisation et d’intégration dans des dispositifs in-body limitent la portée des systèmes existants à quelques dizaines de centimètres. Tout d’abord, des outils spécifiques de modélisation et d’optimisation ont été développés en collaboration avec l’Université de Bohème de l’Ouest. Ces outils sont indispensables pour l’analyse des composants de systèmes antennaires complexes : le code Agros2D (CAO interne) utilise des méthodes entièrement adaptatives. Cette approche permet de réduire la complexité d’optimisation des antennes in-body jusqu’un seul dégrée de liberté. Puis, la limite fondamentale de rendement des antennes pour les applications in-body a été définie ; les liens entre cette limite et la taille de l’antenne, sa fréquence de fonctionnement, la polarisation et les matériaux utilisés (dont hypothétiques) ont été quantifiés pour la première fois. Ce travail fondamental a d’abord pour objectif l’optimisation des performances de l’antenne actuelle de la capsule e-Celsius de l’entreprise BodyCAP pour accroître la portée de la gélule, en prenant en compte les caractéristiques des matériaux et le milieu de propagation que constituent les tissus biologiques. Dans cette étape on inclut également la fabrication des prototypes de gélules télémétriques ainsi que leurs mesures d’impédance. L’antenne optimisée a une portée trois fois plus importante que celle actuelle tout en occupant le même volume. En utilisant ces principes de conception, nous avons développé et caractérisé une antenne à 434 MHz adaptée à une large gamme d'applications in-body. Des dimensions ultra-miniatures, une robustesse et un rendement accrus permettent de l'utiliser à la fois pour des applications des capsules à implanter et à avaler. Enfin, en développant davantage les méthodes de conception et d’optimisation, nous avons conçu une antenne double-bande. Ayant la même robustesse que son équivalent actuel mono-bande, elle présente également un rendement encore plus élevé, permettant ainsi de fonctionner au-delà de 10 m. La caractéristique double-bande permet de concevoir les dispositifs in-body rechargeables sans fil dans le corps. Les antennes proposées contribuent au développement ultérieur d'une nouvelle génération de dispositifs miniatures in-body qui impliquent une intégration complexe et dense des capteurs, de la logique et de la source d'alimentation. / Emerging wireless biotelemetry using miniature implantable, ingestible or injectable (in-body) devices allows continuously monitor and yield human or animal physiological parameters while maintaining mobility and quality of life. Recent advances in microelectromechanical systems and microfluidics—along with ongoing miniaturization of electronics—have empowered numerous innovations in biotelemetry devices, creating new applications in medicine, clinical research, wellness, and defense. Among the typical applications, I can mention, for example, the monitoring of physiological variables: body temperature, blood pressure, heart rate, detection of antibodies, chemical, or biological agents. Biotelemetry devices require a reliable communication system: robust, efficient, and versatile. Improving the transmission range of miniature in-body devices remains a major challenge: for the time being, they are able to operate only up to a few meters. Among the main issues to face are low radiation efficiencies (< 0.1%), antenna impedance detuning, and strong coupling to lossy and dispersive biological tissues. Thus, the main goal of the thesis is to conduct a multi-disciplinary study on development, optimization and characterization of antennas for in-body biotelemetry devices. After state-of-the-art and the context, I start with the development on both physical and numerical approaches to account for the effect of human tissues on the antenna. I propose the methodology to achieve given electromagnetic properties at a given frequency based on the full factorial experiment and surface response optimization. In addition, I describe the spherical physical phantom for the far-field characterization along with a combination of feed decoupling techniques. I proceed by reviewing the trough-body propagation mechanisms and deriving the optimal frequency for the in-body devices. I formulate the problem using four phantoms (homogeneous and heterogeneous) and perform full-wave analysis using an in-house hp-FEM code Agros 2D. Next, I study the existing antenna used by the BodyCap Company for its e-Celsius capsule and the ways on how to improve its operating range and robustness under strict integration and material constraints. The mechanisms of antenna–body coupling are analyzed and the found solution improves the antenna IEEE gain by 11 dBi (the operating range is at least tripled). The existing matching circuit and balun are optimized too for the given application reducing its size from eleven to seven discrete elements. In the following chapters, I continue studying the decoupling of antennas from a body using specific microstrip designs and dielectric loading via capsule shell. By applying the developed approaches, a high robustness and radiation efficiency can be achieved. At first, I develop a proof-of-concept antenna that demonstrates that the perfect matching (detuning immunity) is achievable for the operation within all human tissues. Based on these results, I develop a miniature and versatile biotelemetry platform: a 17 mm x 7 mm alumina capsule containing a conformal 434 MHz antenna. The antenna is well matched to 50 Ohm within the majority of human tissues and operates with an arbitrary device circuitry. Like this, one can use it ''as is,'' applying it for a wide range of in-body applications. Then, I develop a low profile conformal dual-band antenna operating in 434 MHz and 2.45 GHz bands. Such antenna can integrate both data transmission and wireless powering functionality increasing the available space inside an in-body device and increasing its scope of applications. Finally, I present the perspective developments including in-body sensing methodology. The obtained results contributes to further development of a new generation of miniature in-body devices that involve complex and dense integration of sensors, logic, and power sources.

A multiple-antenna-multiple-equalizer (MAME) system is proposed for overcoming cochannel interference (CCI) in code-division multiple access (CDMA) indoor wireless systems. The main advantage of the MAME system is the enhanced interference suppression capability as compared with many existing approaches. Thus, the use of the MAME system can lead to an increase in the capacity of the CDMA system. In the MAME system, a fractionally-spaced equalizer (FSE) is used to process the signal at each antenna. The number of antennas or the tap spacing of the FSEs is not fixed and inherent flexibility is available to the designer. In particular, CDMA indoor wireless systems are best suited to use the interference suppression capabilities of the MAME system. It is shown that spectral correlation present in user signals is the reason for the interference suppression capability of the MAME system. Moreover, the MAME system is interpreted as a dual-domain diversity combiner. Spatial and bandwidth-domain diversity are used and the relative importance of the diversity domains is discussed. These discussions offer new insights into the interference suppression capabilities of the MAME system and give a clear picture of its workings. Extensive simulation results are presented to illustrate the performance of the MAME system under various conditions. Optimal or minimum mean-squared error (MMSE) results are first presented to illustrate the superior interference suppression performance. The effects of the number of antennas, tap spacing, receive filtering, spectral correlation, diversity domains, and near-far conditions on performance are examined and results obtained support the arguments presented earlier in the thesis. The FSEs in the MAME system are implemented as adaptive filters and the mean-squared- error (MSE) performance is investigated. A quasi-Newton (QN) algorithm is recommended over other adaptive filtering algorithms because of ill-conditioning of the autocorrelation matrix in the MAME system. Simulation results confirm the superior convergence performance of the QN algorithm. Decision-directed equalization is also investigated and bit-error rate (BER) results presented illustrate that the gains in the MMSE performance will most likely translate into gains in BER performance. The BER performance in near-far and birth of interferers conditions illustrate that the MAME system is a promising solution to counter these problems. The thesis concludes with an indoor wireless strategy based on the MAME system which offers the following advantages: 1. More users than the processing gain of the CDMA system can share the same bandwidth. 2. No information about code sequences is needed at the receiver. 3. Simple code sequence allocation schemes can be used at the transmitter. 4. Variable numbers of users can be accommodated. 5. Simple power control and error-correction coding schemes can be used. / Graduate

The objective of this paper is to compare antenna simulations to actual measurements using a simulation software tool. This comparison is done using statistical methods in the far field region where the radiation patterns of antennas are plotted on a polar diagram. Actual antenna measurements are carried out in an anechoic chamber. The residual, correlation and sum of squares between simulated data and measured data are calculated. The theoretical directivity value of an antenna is compared to a calculated simulated directivity value. Different methods of creating a vector norm polarplot are outlined and discussed. The numerical method used by the simulation program is outlined.The results achieved will be presented and analyzed. They will also be compared to what we expected to find. The result provided high calculated values, these depend on how the simulated and measured data are matched.

Antenas fractais são estruturas irradiadoras geradas recursivamente a partir da aplicação reiterada de um fator de conjunto gerador, possuindo a característica marcante de ser auto semelhante. São baseadas na teoria dos fractais desenvolvida por Mandelbrot e cuja aplicação se encontra presente em quase todos os ramos da ciência. Tais antenas possuem hoje inúmeras aplicações, de celulares a antenas de satélites, e têm se mostrado uma alternativa atraente para aplicações que requeiram característica de multibanda associada a alto ganho e miniaturização. O presente trabalho procura apresentar de forma sistemática a teoria básica envolvendo antenas fractais, tendo-se por base não apenas as contribuições pioneiras de pesquisadores no mundo todo, mas também a teoria básica de antenas, a partir das quais é possível chegar-se a formulações importantes na área. O foco é para antenas de microfita, dada a grande popularidade que têm encontrado nas últimas décadas. Além de vasta bibliografia, contou-se com o auxílio da ferramenta computacional HFSS da Ansoft®, um software que simula estruturas em alta frequência. Este programa é utilizado para simular uma antena fractal de microfita proposta pelo autor, e os resultados são analisados tendo-se um duplo propósito: exemplificar o uso de uma antena fractal, por um lado, e fornecer um protótipo que porventura poderá ser utilizado em aplicações especiais, por algum projetista de antenas. Os principais parâmetros fundamentais de antenas são analisados, como Perda de Retorno, VSWR, Ganho, etc., mas será dada ênfase especial à aplicação de estruturas fractais de microfita em dois tipos de aplicações: antenas eletricamente pequenas e antenas independentes da frequência. / Fractal Antennas are radiating structures generated recursively from the reiterated application of a generating array, having the remarkable feature of being self similar. They are based on the theory of fractal developed by Mandelbrot and whose application is present in almost every branches of science. Such antennas have many applications today, from cell phones to satellite antennas, and have proved to be an attractive alternative for applications that required multiband characteristic associated with high gain and miniaturization. This paper aims do present systematically the basic theory involving fractal antennas, and is based not only on the pioneering contributions of researchers around the world, but also the basic theory of antennas, from which is possible to reach important formulations in the area. Besides the extensive bibliography, was used the computational tool HFSS by Ansoft®, a software that simulates high frequency structures. This program is used to simulate a fractal microstrip antenna proposed by the author, and the results are analyzed, having a dual propose: to exemplify the use of fractal antenna on the one hand, and providing a prototype which could possible be used in special applications, for some designer of antennas. The main fundamental parameters of antennas are analyzed, such as Return Loss, VSWR, Gain, etc., but special emphasis will be given to the application of fractal microstrip structures in two kinds of applications: electrically small antennas and frequency independent antennas. / Dissertação (Mestrado)

[pt] Neste trabalho analisa-se o efeito do plano de terra nas características de radiação das torres irradiantes, através do relacionamento entre as variações da impedância de entrada e variações na eficiência de radiação. A distribuição de corrente utilizada é a de King e Wu (três termos) que, ao contrário da distribuição senoidal, permite a análise das antenas cujas alturas estejam próximas a meio comprimento de onda. São apresentados resultados para antenas longas e curtas, na faixa de radiodifusão sonora. / [en] The influence of radial wire ground systems in the radiation characteristics of monopole antennas is analyzed through the relationship between the input impedance and the variations of radiation efficiency. Instead of using the sinusoidal current distribution, King and Wu´s distribution is used in order to analyze antennas with lenghes near one half wavelength. Results for long and short antennas and working frequencies in the broadcast band are presented.

This dissertation presents and develops the Intelligent Picocell as a solution for high bit rate, efficient bandwidth indoor wireless communication. The research has examined different aspects of the indoor radio propagation environment and system implementation in order to highlight key benefits of the proposed architecture. Explosive growth in demand for indoor wireless communications motivates research into this novel radio architecture. The architecture should be capable of tailoring capacity and coverage to the needs of the specific indoor environment, while maximising spectral efficiency. The Intelligent Picocell is based on an evolution of the distributed antenna concept to provide macrodiversity, microdiversity and interference cancellation. The architecture is fully scalable to large numbers of users and can provide plug-and-play operation, with no need for detailed system planning beyond the antenna locations. The research examines different aspects of picocell system performance and design, including: Investigation on the indoor radio environment. Through measurements, the effects of building features on path loss and shadowing are analysed and propagation models are proposed for simulating picocell systems. Analysis of the Intelligent Picocell architecture, two algorithms are proposed for interference reduction, one based on a distributed narrowband optimum combiner and the other on a dynamic channel assignment and allocation scheme. Through simulation, it was demonstrated that the mobile transmitted power for an Intelligent Picocell is lower than the power required in a distributed antennas system. It was also shown that the capacity of the system depends on the number of antennas distributed in the building. Key words: Intelligent picocell, adaptive antennas, diversity, distributed antennas, dynamic channel allocation, propagation measurements.

Le travail de cette thèse concerne la conception de nouvelles architectures d'antennes miniatures ou multifréquences en utilisant la technique inspirée des métamatériaux. Les antennes proposées sont munies de nouvelles formes d'éléments parasites qui permettent d'obtenir des structures compactes et donc facilement intégrables dans les terminaux mobiles. Par la suite, l'étude et la conception d'antennes directives et reconfigurables en diagramme de rayonnement par la technique inspirée des métamatériaux a été menée. En première partie, une étude paramétrique sur les paramètres pertinents de la structure a été effectuée afin de bien comprendre le fonctionnement de celle-ci. En deuxième partie, des antennes miniatures et directives sont proposées. Finalement, de nouvelles structures directives et reconfigurables en diagramme de rayonnement sont présentées. / The work of this thesis concerns the design of new architectures of miniature antennas by using the concept of metamaterials-inspired.The proposed antennas integrate new shapes of parasitic elements that allow to obtain compact structures and therefore easily integrated into mobile devices.

Reflectarrays that emulate paraboloidal main-reflectors, and hyperboloidal or ellipsoidal sub-reflectors, have undergone a great deal of development over the past two decades. More recently, research on the topic has concentrated on overcoming some remaining disadvantages, re-examining certain design issues, and extending reflectarray functionality. This thesis concerns itself with fixed-beam offset-fed single-layer main-reflectarrays and sub-reflectarrays comprised of square or rectangular variable size conducting elements. Both full-wave analyses and experiment are used in all the deliberations. In order to examine reflectarray operating mechanisms the thesis first describes a component-by-component technique whereby the role of the various reflectarray parts can be assessed by determining their individual and aggregate contributions to the reflectarray near- and far-fields. This technique is used to diagnose the fact that feed-image-lobes that appear at off-centre frequencies are caused not only by the groundplane as first thought, but by an imbalance in the complex currents on the patches and groundplane at such frequencies. The use of sub-wavelength elements is shown to suppress such unwanted lobes. The thesis then uses receive- and transmit-modes analysis to show that beam squint at off-centre frequencies, often not accounted for when stating the gain bandwidth of a reflectarray, is due to the shifting of the true focal points away from the geometrical one at these frequencies. It is demonstrated that a two-feed reflectarray arrangement is capable of eliminating beam squint, and that the use of smaller focal length to aperture size (F/D) ratios removes the grating lobes that can appear in such two-feed reflectarrays due to clustering of the aperture amplitude distribution. Finally, the thesis studies the effect of the reality that the angle of incidence of the feed fields on the various reflectarray elements is not the same for all elements, even though this is most often assumed when using element reflection phase versus element size databases in performing reflectarray designs. Careful full-wave analysis reveals that it is not only the dependence of element reflection phase on incidence angle that is important, but that the individual element pattern beamwidths change and distort as this angle increases. This is important not only from the point of view of the coupling of the feed fields to the elements, but also as far as the angular sector within which the reradiated fields are important. Thus sub-reflectarrays, whose radiation patterns are considerably wider than main-reflectors, are more susceptable to incidence angle effects. It is shown that the use of sub-wavelength elements in a reflectarray largely ensures its immunity to such effects.

<p>Satellite Look Angles are the coordinates to which an earth station antenna must point to communicate with a satellite. Each satellite has it's own unique set of look angles. The first method, developed to calculate a satellite's look angles, uses standard plane and spherical trigonometry and assumes a perfectly spherical earth. The second method developed is unique to this paper and wi11 not be found anywhere, including general satellite communication textbooks. This method uses a geodetic reference system which refers to the earth as an ellipsoid rather than a sphere. This second method is a more rigorous approach to determining look angles and readily lends itself to pointing at satellites in any given orbit. Fortran code was written implementing both methods and it is concluded that employing a geodetic reference frame is viable where high degrees of accuracy are required. Fortran code was also developed to calculate the pointing angles for Radio Sources such as pulsars and quasars. This code corrects for precession, nutation, annual aberration, and polar motion of the earth.</p> / Master of Science

Le projet ARTIC, Application de la RFID pour la traçabilité des Instruments chirurgicaux, concerne la mise en place d'une solution d’automatisation de la traçabilité dans le secteur hospitalier, en particulier dans la stérilisation et dans la salle d'opération. Le développement d'une telle solution pose plusieurs problèmes. En effet le contrôle et e suivi des instruments doit être rapide et adapté à l'environnement de travail, en tenant compte des exigences inhérentes à ces instruments: stérilisation à l'autoclave (121-138 ° C, vapeur saturée, 1-2 bar) et utilisation par les chirurgiens. La spécification doit combiner l'ergonomie, la résistance à l'autoclave et la fiabilité, tout en étant rapide et générer un petit coût supplémentaire. De plus, une telle solution, doit permettre un contrôle multiple (identification de plusieurs instruments à la fois) dans toutes les directions spatiales possibles (sachant que les instruments sont posés d’une manière aléatoire dans les bacs de stérilisation). La thèse sur la traçabilité RFID à l'aide de petites antennes a pour but de proposer des solutions prototype basé sur le couplage entre les boucles du lecteur et celle du tag, l’optimisation des prototypes a pour but d’atteindre une distance de communication allant jusqu'à 10cm en utilisant une grande antenne du lecteur (ayant la taille des bacs de stérilisation : 50 cm de longueur) et un tag miniature (quelques millimètres). Plusieurs prototypes sont proposés et développés. (1) un prototype antenne du lecteur incluant des résonateurs, qui permet d'augmenter le couplage du système RFID HF. Cette structure a été simulée, réalisée et mesurée. Afin de mettre un lien entre la simulation et la mesure, nous avons développé des modèles d'équations empiriques qui nous permettent à la fois de retrouver l'inductance propre d'un système lecteur N-boucles et aussi l'inductance mutuelle équivalente du système. (2) Une autre solution est une structure multi-boucles torsadées. Elle est basée sur la réorientation des lignes de champ magnétique. Son intérêt est de permettre une détection des tags quel que soit leurs positionnements angulaires / The ARTIC project, concerns the implementation an automatically system used to Tracking Surgical Instruments with Radio Frequency Identification in hospitals, more precisely particular in sterilization and operating room. The development of such solution needs to solve several problems. The control of the instruments must be rapid and adapted to the sterilization: autoclave sterilization (121-138 ° C, 1-2 bar). The specification must combine ergonomics, autoclave resistance and reliability, while being fast and generating low additional cost. Moreover, such a solution must allow multiple control (identification of several instruments at a time) in all possible spatial directions. The thesis on RFID tracking using small antennas aims to propose prototype solutions based on the magnetic coupling between reader and the tag loops. The purpose of the prototype optimization is to reach a communication distance up to 10 cm using a large reader loop antenna (the size of the sterilization trays: 50 cm length) and a miniature tag (few millimeters). Several prototypes are proposed and developed. (1) a prototype of the reader loop antenna including resonators, which allows to increase the magnetic coupling of the RFID system. This structure is simulated, realized and measured. In order to make a link between simulation and measurement, we developed calculations of the equivalent electrical model that allow to find the equivalent inductance of the N-loop reader antenna and also the equivalent mutual inductance of the system entire system. (2) Another solution is a multiple twisted loop reader antenna. It is based on the reorientation of the magnetic field lines. Its interest is to allow a detection of the tags whatever their angular positioning