This thesis introduces, for the first time, a novel 4-bit, metal-oxide-metal (MOM) digital capacitor switching array (MOMDCSA) which has been implemented into a wideband CMOS voltage controlled oscillator (VCO) for 5 GHz WiMAX/WLAN applications. The proposed MOMDCSA is added both in series and parallel to nMOS varactors. For further gain linearity, a wider tuning range and minor phase noise variations, this varactor bank is connected in parallel to four nMOS varactor pairs, each of which is biased at a different voltage. Thus, VCO tuning gain reduces and optimal phase noise variation is obtained across a wide range of frequencies. Based on this premise, a wideband VCO is achieved with low phase noise variation of less than 4.7 dBc/Hz. The proposed VCO has been designed using UMC 130 nm CMOS technology. It operates from 3.45 GHz to 6.23 GHz, with a phase noise of -133.80 dBc/Hz at a 1 MHz offset, a figure of merit (FoM) of -203.5 dBc/Hz. A novel microstrip low-phase noise oscillator is based on a left-handed (LH) metamaterial bandpass filter which is embedded in the feedback loop of the oscillator. The oscillator is designed at a complex quality factor Qsc peak frequency, to achieve excellent phase noise performance. At a centre frequency of 2.05 GHz, the reported oscillator demonstrates, experimentally, a phase noise of -126.7 dBc/Hz at a 100 kHz frequency offset and a FoM of -207.2 dBc/Hz at a 1 MHz frequency offset. The increasing demands have been placed on the electromagnetic compatibility performance of VCO devices is crucial. Therefore, this thesis extends the potential of highly flexible and conductive graphene laminate to the application of electromagnetic interference (EMI) shielding. Graphene nanoflake-based conductive ink is printed on paper, and then it is compressed to form graphene laminate with a conductivity of 0.43×105 S/m. Shielding effectiveness is experimentally measured at above 32 dB as being between 12GHz and 18GHz, even though the thickness of the graphene laminate is only 7.7µm. This result demonstrates that graphene has great potential for offering lightweight, low-cost, flexible and environmentally friendly shielding materials which can be extended to offering required shielding from electromagnetic interference (EMI), not only for VCO phase noise optimisation, but also for sensitive electronic devices.

[pt] Linhas de transmissão de energia são estruturas importantes em um sistema de energia elétrica. Devido à elevada energia transportada por essas redes, falhas em linhas de transmissão podem ter reflexos severos no fornecimento aos consumidores, não raro levando a apagões em áreas geograficamente extensas. Entre as possíveis origens de falhas está o rompimento dos cabos elétricos pela fadiga provocada pela vibração eólica. As grandes extensões territoriais percorridas pelas linhas de transmissão e a variedade de climas, relevos, vegetação e condições meteorológicas aos quais estão submetidas dificultam qualquer trabalho de previsão da ação do vento. A medição da vibração permite detectar de antemão a aproximação da falha, porém os instrumentos convencionais dependem de transdutores elétricos os quais, além de exigirem uma fonte de energia (normalmente não disponível junto a linhas de transmissão) para seu funcionamento, sofrem influência dos intensos campos elétricos e magnéticos existentes em torno dos cabos de energia. A imunidade das fibras ópticas a campos elétricos e magnéticos e a possibilidade de uso de sinal de entrada de baixa potência oferecem uma alternativa para a criação de instrumentos de medição usando a técnica das redes de Bragg. A presente dissertação contribui com o desenvolvimento de um acelerômetro biaxial a redes de Bragg para medição de vibração em cabos de linhas de transmissão de energia. Além dos aspectos teóricos e práticos envolvidos, são discutidos os resultados de ensaios de calibração de elevada exatidão e outros ensaios especiais que fundamentaram a avaliação metrológica e o estabelecemento da eficácia do referido instrumento. / [en] Overhead transmission lines play an important role on electric systems. Due to the high energy carried through those networks, failures on overhead lines can bring severe constraints on consumers supply, occasionally taking the form of blackouts in large geographic regions. Among the reasons of such failures is the breaking of electric cables caused by the fatigue originated from cyclic bending due to aeolian vibration. The large areas covered by overhead lines and the variety of climate, relief, vegetation and meteorological conditions under which they have to operate make it difficult to foresee the impact of wind Vibration measurements would allow anticipating the failure but conventional instruments depend upon electric transducers which, besides demanding a local source of energy (usually unavailable near overhead lines), suffer the influence of the high electric and magnetic fields around the energized cables. Optical fibers immunity against environments subjected to electrical and magnetic fields and the possibility of using low energy input signals offer the alternative of creating measuring instruments using Bragg gratings technique. This Master dissertation contributes with the development of a fiber Bragg grating biaxial accelerometer for measuring the vibration of overhead transmission line cables. Besides the theoretical and practical aspects related to the subject, the results of high precision calibration tests are discussed, together with other special tests which set the basis of the metrological evaluation and the establishment of the efficacy of the instrument.

<div> <div> <div> <div> <p>This dissertation presents and develops a novel method of wireless power transfer that relies on electromagnetic coupling from open-wire transmission lines instead of tra- ditional methods. Wireless power transfer techniques are being rapidly pursued in re- search currently due to the potential utility of powering devices over the air instead of with direct electrical connections. Uses for such techniques include an array of ap- plications from consumer electronics, to medical devices, to cars and UAVs. While con- ventional wireless power transfer techniques exist, it is shown here that open-wire trans- mission line methods present distinct advantages for certain applications. In particular, wireless power transfer using Goubau and twin-lead line architectures will be conceptual- ized and investigated in terms of their theory, design, and efficiency performance. Fur- ther, a circuit model theory will be developed in this work to provide a generalized for- mulation for open-wire-line wireless power transfer analysis. Additionally, receiver de- sign techniques will be outlined and geometries based on metamaterial principles will be pursued in order to achieve receiver miniaturization and access the applications this af- fords. </p> </div> </div> </div> </div>

<p>Nonlinear transmission lines (NLTLs) are of great interest for high power microwave (HPM) generation because they can sharpen pulses to create an electromagnetic shockwave to produce oscillations from 100 MHz to low GHz. NLTLs provide frequency agility, compactness, durability and reliability, providing a solid-state radiofrequency (RF) source for producing HPM. The essential component of NLTLs is the nonlinear material, typically a dielectric that varies with voltage or a magnetic material whose permeability varies with current, incorporated in the transmission line in various topologies. This thesis presents an alternative approach involving designing composites comprised of nonlinear dielectric inclusions (barium strontium titanate (BST)) and/or nonlinear inductive inclusions (nickel zinc ferrites (NZF)) in a polymer base host material, analogous to electromagnetic interference designs that incorporate stainless steel inclusions of various shapes in a plastic to tune the composite’s electromagnetic properties at GHz. Appropriately designing NLTL composites requires predicting these effective properties both in linear (for a fixed and low voltage and current) and nonlinear regions (permittivity and permeability become voltage dependent and current dependent, respectively) prior to designing HPM systems comprised of them. As a first step, this thesis evaluates and benchmarks composites models in the commercial software CST Microwave Studios (CST MWS) to various effective medium theories (EMTs) to predict the permittivity and permeability of composites of BST and/or NZF inclusions in the linear regime, compared with experimental measurements. The manufacturing and measurement of the nonlinear composites will be briefly discussed with an analysis of the homogeneity of a composite sample using 3D X-ray scan. Long-term application of these approaches to predicting the effective nonlinear composite permittivity and permeability and future work will be discussed.</p>

<p>Nonlinear transmission lines (NLTLs) provide a solid state alternative to conventional vacuum based high power microwave (HPM) sources. The three most common NLTL implementations are the lumped element, split ring resonator (SRR), and the nonlinear bulk material based NLTLs. The nonlinear bulk material implementation provides the highest power output of the three configurations, though they are limited to pulse voltages less than 50 kV; higher voltages are possible when an additional insulator is used, typically SF₆ or dielectric oil, between the nonlinear material and the outer conductor. The additional insulator poses a risk of leaking if structural integrity of the outer conductor is compromised. The desire to provide a fieldable NLTL based HPM system makes the possibility of a leak problematic. The work reported here develops a composite based NLTL system that can withstand voltages higher than 50 kV and not pose a risk of catastrophic failure due to a leak while also decreasing the size and weight of the device and increasing the output power.</p> <p>Composites with barium strontium titanate (BST) or nickel zinc ferrite (NZF) spherical inclusions mixed in a silicone matrix were manufactured at volume fractions ranging from 5% to 25%. The dielectric and magnetic parameters were measured from 1-4 GHz using a coaxial airline. The relative permittivity increased from 2.74±0.01 for the polydimethylsiloxane (PDMS) host material to 7.45±0.33 after combining PDMS with a 25% volume fraction of BST inclusions. The relative permittivity of BST and NZF composites was relatively constant across all measured frequencies. The relative permeability of the composites increased from 1.001±0.001 for PDMS to 1.43±0.04 for a 25% NZF composite at 1 GHz. The relative permeability of the 25% NZF composite decreased from 1.43±0.05 at 1 GHz to 1.17±0.01 at 4 GHz. The NZF samples also exhibited low dielectric and magnetic loss tangents from 0.005±0.01 to 0.091±0.015 and 0.037±0.001 to 0.20±0.038, respectively, for all volume fractions, although the dielectric loss tangent did increase with volume fraction. For BST composites, all volume fraction changes of at least 5% yielded statistically significant changes in permittivity; no changes in BST volume fraction yielded statistically significant changes in permeability. For NZF composites, the change in permittivity was statistically significant when the volume fraction varied by more than 5% and the change in permeability was statistically significant for variations in volume fraction greater than 10%. The DC electrical breakdown strength of NZF composites decreased exponentially with increasing volume fraction of NZF, while BST composites exhibited no statistically significant variation with volume fraction. </p> <p>For composites containing both BST and NZF, increasing the volume fraction of either inclusion increased the permittivity with a stronger dependence on BST volume fraction. Increasing NZF volume fraction increased the magnetic permeability, while changing BST volume fraction had no effect on the composite permeability. The DC dielectric breakdown voltage decreased exponentially with increased NZF volume fraction. Adding as little as 5% BST to an NZF composite more than doubled the breakdown threshold compared to a composite containing NZF alone. For example, adding 10% BST to a 15% NZF composite increased the breakdown strength by over 800%. The combination of tunability of permittivity and permeability by managing BST and NZF volume fractions with the increased dielectric breakdown strength by introducing BST make this a promising approach for designing high power nonlinear transmission lines with input pulses of hundreds of kilovolts.</p> <p>Coaxial nonlinear transmission lines are produced using composites with NZF inclusions and BST inclusions and driven by a Blumlein pulse generator with a 10 ns pulse duration and 1.5 ns risetime. Applying a 30 kV pulse using the Blumlein pulse generator resulted in frequencies ranging from 1.1 to 1.3 GHz with an output power over 20 kW from the nonlinear transmission line. The output frequencies increased with increasing volume fraction of BST, but the high power oscillations characteristic of an NLTL did not occur. Simulations using LT Spice demonstrated that an NLTL driven with a Blumlein modulator did not induce high power oscillations while driving the same NLTL with a pulse forming network did. </p> <p>Finally, a composite-based NLTL could be driven directly by a high voltage power supply without a power modulator to produce oscillations both during and after the formed pulse upon reaching a critical threshold. The output frequency of the NLTLs is 1 GHz after the pulse and ranged from 950 MHz to 2.2 GHz during the pulse. These results demonstrate that the NLTL may be used as both a pulse forming line and high power microwave source, providing a novel way to reduce device size and weight, while the use of composites could provide additional flexibility in pulse output tuning. </p>

Cette thèse traite des problématiques relatives à la modélisation, l’analyse et la simulation des systèmes électriques interconnectés. Elle a été principalement motivée par le besoin de comprendre et de clarifier les niveaux de modélisation de certains composants électriques comme les lignes de transmission ainsi que leur habilité à reproduire les différents phénomènes qui présentent un intérêt dans le système. En effet, pour faciliter les études et les simulations, les modèles les plus détaillés et les plus complexes sont généralement remplacés par des modèles plus simples selon le type des phénomènes visés. Usuellement, la structure dynamique de l’ensemble du système n’est pas prise en compte dans l’étape de simplification, ce qui fait que, dans la plupart du temps, des validations expérimentales sont nécessaires. C’est pourquoi un cadre structurel et une vision systémique sont proposés dans cette thèse afin d’apporter des solutions plus générales et plus fiables qui s’adaptent mieux à l’approximation des systèmes électriques. Le cadre proposé il nous a permis : d’une part, d’expliquer par le biais de la réduction l’approximation du modèle à paramètres distribués d’une ligne par un modèle plus simple de dimension finie appelé π et d’autre part, d’étendre les investigations à une échelle plus grande où une nouvelle méthodologie de troncature est proposée pour l’approximation des modèles dynamiques de grande taille. Elle se distingue des méthodes standards par l’efficacité d’évaluation des dynamiques du système même dans des situations particulières ainsi que la prise en compte de divers besoins pratiques. Il s’agit d’une approche mixte qui combine, d’une part, le principe de la troncature modale et, d’autre part, l’énergie de la réponse impulsionnelle afin de préserver les structures dynamique et physique du système. A cela s’ajoute également la question du nombre et choix des entrées des systèmes à paramètres distribués qui est posée ici d’un point de vue de l’automatique afin de lui donner plus d’utilité pratique, surtout dans les simulateurs numériques. L’approche utilisée à cet effet est algébrique, et la contribution est une étude assez détaillée de l’état de l’art sur le sujet qui a finalement affiné d’avantage la problématique et conduit à de nouvelles pistes plus prometteuses car la question est jusqu’alors partiellement résolue. Plus précisément, les investigations doivent se concentrer désormais sur les commandes dites aux bords ou frontières.D’un point de vue pratique, les résultats obtenus dans cette thèse peuvent être exploités dans l’avenir pour améliorer et facilité les techniques actuelles de simulation et d’analyse en adaptant, par exemple, chaque modèle utilisé aux phénomènes à reproduire. / This thesis was motivated by the need to better understand the connection between the models used in simulation of the power systems dynamics and the phenomena which have to be analyzed or reproduced by the simulation. Indeed, to study and to simulate the behavior of the interconnected power systems, the sophisticated models such as the one of the transmission lines are generally replaced by simple ones. Usually, a dynamic structure of the whole system is not taken into account in a simplification step. As a consequence, experimental validations are generally needed to assess the result of the approximation. For this reason, a structural framework and a systemic viewpoint are proposed to make the solutions more general and more appropriate to the approximation of power systems. First, this allows explaining the link between the distributed parameters model of the transmission lines and the finite dimensional one called π model based on the model reduction. Next, a novel mixed approximation methodology for large-scale dynamic models is proposed which allows one to better rate the dynamics of the system in different situations, and to take into account several practical needs. This methodology is based on a mixture between the modal truncation and the energy of the impulse response so that the dynamical and the physical structures of the system remain unchanged. Moreover, in the context of the automatic control theory, the issue related to a number and a choice of input variables for distributed parameters systems is discussed. To address this issue, an algebraic approach is applied. Here, the main contribution is the detailed study conducted on the basis of the state of the art by which a new way is proposed. Because the issue is not fully solved, more investigations have to be focused on the so called boundary control variables. For practical applications, all the results presented in this study can be exploited to further improve numerical simulations and behavioral studies of large-scale power systems.

With increasing frequency up to the THz frequency range and the desire to optimize performance of modern applications, precise knowledge of the dielectric material parameters of a substrate being used in a planar application is crucial: High performance of the desired device or circuit can often be achieved only by properly designing it, using specific values for the material properties. Especially the integration of planar devices for very broadband applications at high frequencies often demands specific dielectric properties such as a low permittivity, dispersion and loss, assuring a predictable performance over a broad frequency range. Therefore, material characterization at these frequencies is of interest to the developing THz community, although not a lot of methods suitable in terms of frequency range and measurement setup exist yet. In this work, a comprehensive method for dielectric material parameter determination from S-Parameter measurements of unloaded and loaded planar transmission lines up to THz frequencies is developed. A measurement setup and methodology based on wafer prober measurements is established, which allows for characterization of planar substrates and bulk material samples alike. In comparison with most existing methods, no specialized measurement cell or cumbersome micro-machining of material samples is necessary. The required theory is developed, including a discussion of effective parameter extraction methods from measurement, identification of and correction for undesired transmission line effects such as higher order modes, internal inductance and surface roughness, as well as mapping and modelling procedures based on physical permittivity models and electromagnetic simulations. Due to the general approach and modular structure of the developed method, new models to cover additional aspects or enhance its performance even further are easily implementable. Measurement results from 100 MHz to 500 GHz for planar substrates and from 100 MHz to 220 GHz for bulk material samples emphasize the general applicability of the developed method. It is inherently broadband, while the upper frequency limit is only subject to the fabrication capabilities of modern planar technology (i.e. minimum planar dimensions of transmission lines and height of substrate) and thus is easily extendable to higher frequencies. Furthermore, the developed method is not bound to a specific measurement setup and applicable with other measurement setups as well, as is exemplary presented for a free-space setup using antennas, enabling measurement of large, flat material samples not fitting on the wafer prober. Several substrate and bulk material samples covering a wide range of permittivities and material classes are characterized and compared with reference values from literature and own comparison measurements. The uncertainties for both planar substrate as well as bulk material sample measurements are estimated with a single-digit percentage. For all measurements, the order of magnitude of the dielectric loss tangent can be determined, while the lower resolution boundary for bulk material sample measurements is estimated to 0.01. Concerning measurements in the wafer prober environment, fixture-related issues are a main cause of measurement uncertainty. This topic is discussed as well as the design of on-wafer probe pads and custom calibration standards required for broadband operation at THz frequencies. / Mit zunehmender Erschließung des THz-Frequenzbereichs und der zugehörigen Optimierung moderner Anwendungen ist eine genaue Kenntnis der dielektrischen Materialparameter verwendeter planarer Substrate unabdingbar: Eine hohe Performance angestrebter Bauteile oder Schaltungen kann nur durch einen präzisen Entwurf sichergestellt werden, wofür spezifische Werte für die Materialeigenschaften bekannt sein müssen. Insbesondere die Integration planarer Bauelemente für sehr breitbandige Anwendungen bei hohen Frequenzen bedingt spezifische dielektrische Materialeigenschaften, wie bspw. geringe Permittivität, Dispersion und Verluste, sodass eine vorhersagbare Performance über einen breiten Frequenzbereich sichergestellt werden kann. Materialcharakterisierung bei diesen Frequenzen ist folglich von Interesse für die sich entwickelnde THz-Forschungslandschaft, wenngleich derzeit kaum Verfahren existieren, die geeignet in Bezug auf den Frequenzbereich oder Messaufbau sind. Im Rahmen dieser Arbeit wird ein umfassendes Verfahren zur Bestimmung der dielektrischen Materialparameter aus S-Parameter-Messungen unbelasteter und belasteter planarer Leitungen bis in den THz-Bereich entwickelt. Ein Messaufbau mitsamt Messmethodik basierend auf Wafer Prober-Messungen wird entworfen, welcher die Charakterisierung von planaren Substraten und losen Materialproben ermöglicht. Im Vergleich zu existierenden Verfahren ist weder eine spezielle Messzelle noch eine umständliche Mikrobearbeitung der Materialproben notwendig. Die Entwicklung der hierfür notwendigen Theorie beinhaltet eine Diskussion von Methoden zur Extraktion effektiver Parameter aus Messungen, die Identifikation und Korrektur unerwünschter Leitungseffekte wie bspw. höherer Moden, interner Induktivität und Oberflächenrauhigkeit sowie Zuordnungs- und Modellierungsverfahren basierend auf physikalischen Permittivitätsmodellen und elektromagnetischen Simulationen. Durch den allgemeinen, modularen Ansatz des entwickelten Verfahrens lassen sich neue Modelle zur Berücksichtigung zusätzlicher Effekte oder weiteren Verbesserung der Performance einfach einarbeiten. Messergebnisse von 100 MHz bis 500 GHz für planare Substrate und von 100 MHz bis 220 GHz für lose Materialproben unterstreichen die allgemeine Anwendbarkeit des entwickelten Verfahrens. Es ist inhärent breitbandig, wobei eine obere Frequenzgrenze nur durch die Fertigungstoleranzen moderner planarer Technologien gegeben ist (minimale Leitungsdimensionen und Substrathöhe), sodass es einfach zu höheren Frequenzen hin erweiterbar ist. Weiterhin ist das entwickelte Verfahren nicht an einen bestimmten Messaufbau gebunden und auch mit weiteren Aufbauten anwendbar, wie beispielhaft an einem Freiraum-Aufbau mit Antennen präsentiert wird. Eine Vielzahl planarer Substrate und loser Materialproben, die ein weites Spektrum an Permittivitäten und Materialklassen abdecken, werden charakterisiert und mit Referenzdaten aus der Literatur sowie eigenen Messungen verglichen. Die Messunsicherheiten der Permittivitätsmessungen werden im einstelligen Prozentbereich abgeschätzt und der dielektrische Verlustwinkel kann in seiner Größenordnung bestimmt werden. Aufbaubezogene Einflüsse als eine Hauptursache für Messunsicherheiten am Wafer Prober werden adressiert, ebenso wie der Entwurf von On-Wafer Probe Pads und selbsterstellter Kalibrierstandards, die notwendig sind für den Einsatz bei THz-Frequenzen.

[pt] Muitos drones subaquáticos (DSs) modernos usados no monitoramento militar e ambiental operam no oceano e são concebidos como transceptores intermediários entre sua estação base (EB) e redes de sensores sem fio subaquáticas (RSSFSs). Devido a salinidade e consequentemente a condutividade da água do mar, DSs não podem usar transmissões de rádio frequência (RF) convencionais, tanto para alimentar quanto para se comunicar com os nós sensores (NSs). Tentando superar essas limitações, sistemas de transmissão indutiva de energia (TIE) têm sido apontados como uma alternativa para RSSFSs assistidas por DSs confiáveis. TIE apresenta perdas menores do que técnicas de campo distante em meios complexos, mas é extremamente limitada em termos de distância de operação. Baseado nisso, a presente tese visa uma solução mais integrada para sistemas de monitoramento assistidos por DSs baseado em sistemas de TIE usando lentes e refletores de metamaterial (MTM) dedicados a aprimorar ambas a eficiência na transmissão de energia e a razão sinal-ruído dos dados transmitidos. Um novo modelo do canal magnético, baseado no modelo de linhas de transmissão magnéticas virtuais, incorporando os ganhos dos MTMs e as perdas da água do mar, também é apresentado de modo a facilitar a futura sistematização das RSSFSs. / [en] Most modern underwater drones (UDs) employed in military and environmental monitoring operate in the ocean and are conceived as intermediary transceivers between their base station (BS) and underwater wireless sensor networks (UWSNs). Due to the salinity and consequently the conductivity of seawater, UDs cannot use conventional radiofrequency (RF) transmissions, either for powering or communicating with the sensor nodes (SNs). Trying to overcome these limitations, inductive power transmission (IPT) systems have been pointed out as an alternative for reliable UD-assisted UWSNs. IPT presents lower losses than far-field-based techniques in complex media but is extremely limited in terms of operating distance. Based on that, the present thesis aims an all-integrated solution for UD-assisted monitoring systems based on IPT systems using metamaterial (MTM) lenses and reflectors dedicated to improving both the power transfer efficiency and the signal-noise ratio of the transmitted data. A new model of the magnetic channel, based on the virtual magnetic transmission line model, incorporating the MTM gains and the seawater losses, is also presented in order to facilitate the future systematization of UWSNs.

Диплом посвящен описанию методики моделирования системы передачи данных на симметричных линии передач. Приведена методика построения моделей систем в программной среде NI AWR Design Environment. Производится разбор этапов построения модели. / Diploma is dedicated to the describe method of modeling of transmission system build upon symmetric transmission lines. Method of modeling in NI AWR Design Environment been presented. An extensive explanation of modeling process is given.

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