This dissertation proposes novel solutions for important drawbacks of antenna arrays. One of the main contributions of the presented work is size reduction and nulling performance improvement of traditionally large anti-jam global positioning system (GPS) arrays using miniature antennas and electrically small resonators emulating an engineered metamaterial. Specifically, a miniaturized coupled double loop (CDL) dual band antenna is first introduced as a small antenna element of the compact GPS array. The loops that are capacitively coupled using lumped element capacitor, and employ metallic pins around their perimeter to improve the radiation efficiency by achieving a volumetric current distribution. This design is employed for the implementation of a compact 2x2 GPS array by reducing the inter-element spacing between the adjacent elements. However, having the antenna elements in close proximity of each other yields to a high mutual coupling and potentially degrades the nulling performance. The mutual coupling is performed by observing the magnetic field distribution within the array. It is noticed that the mutual coupling can be reduced by using metamaterial resonators. The right hand circular polarization (RHCP) radiation nature of the array complicates the mutual coupling suppression as compared to linear arrays. It is determined that split ring resonator (SRRs) are effective to mitigate the mutual coupling problem if placed strategically around the antenna elements. The study is verified experimentally where the mutual coupling is reduced by more than 10 dB. Lowering the mutual coupling improved the array's nulling capability by increasing the nulls depth by 8 dB as well as enhancing the accuracy of the nulls' locations. The second major contribution of the presented work is to introduce a novel microfluidic based beam-scanning technique for the implementation of low cost mm-wave antenna arrays. Traditionally, beam scanning capability is obtained using mechanical steering of the entire antenna structure or electronic components such as switches or phase shifters. The former is bulky, whereas the latter technique requires integrating substantial and expensive hardware in the array's feed network. For instance, a beam-scanning 1x8 focal plane array (FPA) would employ 7 single pole double through (SPDT) switches in its feed network. If an 8x8 FPA is desired, then 8x7+8 switches are required that results in an efficient design in terms of power loss and cost. In this dissertation, the microfluidic principles are introduced for designing and implementing affordable beam scanning antenna array with high gain radiation. Specifically, a microfluidic-based focal plane array 1x8 (MFPA) is designed and implemented at 30 GHz. The proposed MFPA consists of microfluidic channels connecting reservoirs. Both of the channels and reservoirs are filled with a low loss dielectric solution, and the antenna is formed by using a small volume of liquid metal. The beam scanning capability is obtained by placing the array at the focal point of a microwave lens and moving the antenna among the reservoirs using a micropump. Therefore, the feed network is extremely simplified by avoiding using SPDT switches. In addition, a strategic design methodology for a completely passive resonant based corporate feed network is discussed. The array is characterized numerically and verified experimentally. The simulated and measured performances are in a very good agreement with ±300 FoV and > 21 dB realized gain. However, the array's radiation pattern exhibits high side lobe level (SLL) due to the resonant nature of the introduced corporate feed network. Consequently, new resonant and non-resonant straight based feed networks are introduced to alleviate the high SLL issue. Moreover, they are modeled with appropriate equivalent circuits in order to analyze the array's performance analytically in terms of -10 dB |S11| bandwidth and power loss. The analytical solution is based on the transmission line theory and two ports network analysis. It is verified with the full wave simulations and a very good agreement is observed. Using the straight feed network reduces the SLL to more than 20 dB relative the pattern's peak. This enhancement in the performance is verified experimentally as well by designing, fabricating and testing a 30 GHz MFPA fed using a resonant based straight network. A ±250 FoV is obtained with a SLL < -20 dB and 4% -10 dB |S11| bandwidth.

Recent years have seen a growing interest in a new kind of periodic structures called ``metamaterials'. These new artificial materials exhibit many new appealing properties, not found in nature, and open many new possibilities in the domain of antenna design. This thesis describes efficient numerical tools and methods for the analysis of infinite and finite periodic structures. A numerical simulation code based on the Method of Moments has been developed for the study of both large phased arrays and periodic metamaterials made of metal and/or dielectrics. It is shown how fast infinite-array simulations can be used in a first instance to approximately describe the fields radiated by large antenna arrays or compute transmission and reflection properties of metamaterials. These infinite-array simulations rely on efficient computation schemes of the doubly periodic Green’s function and of its gradient. A technique based on eigenmode analysis is also described, that allows to efficiently compute the dispersion curves of periodic structures. Accounting for the finiteness of real structures is possible in good approximation thanks to a finite-by-infinite array approach. Moreover, the excitation of large finite periodic structures by a single (non periodic) source can be studied by using a combination of the Array Scanning Method with a windowing technique. All these techniques were validated numerically on several examples and it is finally shown how they can be combined to design high gain antennas, based on metamaterial superstrates excited by a slotted waveguide. The proposed design method relies on the separation of the whole structure in two different problems. An interior problem is used to optimize the input impedance of the antenna, while the radiation pattern can be optimized in the exterior problem.

Based on the Lyapunov stability theorem, a modified stability analysis as well as a modified observer is proposed in this thesis for a class of uncertain nonlinear systems with an existent high gain observer. By assuming that the first two state variables are indirectly measurable, reanalyzing the stability of the error dynamics is presented first. The advantage of this modified analytic method is that the upper bound of the disturbance distribution functions is not required to be known in advance, and the asymptotic stability is still guaranteed. Next, based on this existent observer, a slightly modified observer is presented for systems with disturbances whose upper bound is unknown. An adaptive mechanism is embedded in the proposed observer, so that the upper bound of perturbations is not required to be known beforehand. The resultant dynamics of estimation errors can be driven into the sliding surface in a finite time, and guarantee asymptotic stability. A numerical example and a practical example are given to demonstrate the feasibility of the proposed observer.

In this thesis, we introduce a LHM (Left-Handed Material) with both negative permittivity and permeability. Improvement of gain antenna is achieved by utilizing the characteristics of the LHM which can focus the EM wave. We start with an analysis of electromagnetic characteristic of LHM, especially its negative index of refraction. Structures with only negative permittivity or negative permeability are also analyzed. Then, we design the structure of LHM that can reduce the sensitivity of S11 of an antenna. So that the antenna operating frequency is not changed even in the presence of the LHM. The LHM unit cell structure comes from the idea by combination of two basic SNG (Single Negative) structure. We design a unit cell whose index of refraction is negative and close to zero. Further, we combine LHM and antenna. Simulation and measurement results show that the LHM is effective. The reflection coefficient of antenna does not change much by the combination of proposed LHM. The half power beam¡Ðwidth of antenna become narrower. The antenna gain improvement can be about 3 dB or higher. Finally, the LHM has been miniaturized successfully, resulting in reduction in size by about 50%. Comparing simulation and measurement, we find the LHM is still effective. A dipole antenna is used to verify out design. The antenna gain has been enhanced and the reflection coefficient does not change much.

Syftet med den här undersökning var att se hur mycket jag som gitarrist och producent kan efterlikna olika typer av high gain elgitarrljud. Jag använde mig av modelleringsförstärkare och rördrivna elgitarrförstärkare med högtalarelement. Frågan var vilken av dessa förstärkartyper kommer egentligen närmast ett original? Hur mycket av karaktären ljudet sitter i anslag jämfört med mängd och karaktär av distorsion? För att få en överblick på hur bra jag lyckades att efterlikna olika gitarrljud har jag arbetat med tre olika soundalikes. Dessa tre låtar är tre exempel på hur olika high gain elgitarrer kan låta inom genren metal. Resultatet mynnade ut i att jag som gitarrist fick reda på hur mycket av ett elgitarrljud som faktiskt sitter i min spelstil och anslag. Jag fick även reda på att den förstärkartyp jag är van vid har en stor påverkan på hur jag skapar och försöker efterlikna olika ljud.

Ce manuscrit porte sur la synthèse d'observateurs grand gain pour des systèmes non linéaires à sorties échantillonnées et retardées. Trois contributions sont proposées à la lecture de ce manuscrit. La première contribution, pour une classe de systèmes Multi-entrées / Multi-sorties uniformément observables et dont les sorties sont regroupées en un seul bloc, met en jeu le problème du processus d'acquisition des mesures de sorties (continues, échantillonnées, retardées ou non) et propose un cadre commun pour l'ensemble des cas possibles. La deuxième contribution propose un observateur grand gain filtré sur cette même classe de systèmes dans l'optique de réduire la sensibilité au bruit de mesure, dans le cas où la sortie est continue puis dans le cas où cette dernière est échantillonnée. La dernière contribution vise à étendre la synthèse grand gain standard pour une large classe de systèmes Multi-entrées / Multi-sorties uniformément observables dont les mesures des sorties sont continues. Pour chacune de ces contributions, il a été montré que l'erreur d'observation de chacun des observateurs proposés converge exponentiellement vers zéro en l'absence d'incertitudes sur le système. Toutes ces contributions ont été illustrées par différents exemples issus de plusieurs domaines d'étude. / This manuscript deals with the synthesis of high gain observers for nonlinear systems with sampled and delayed outputs. Three contributions are proposed for consideration in this manuscript. The first contribution, for a class of Multi-input / Multi-output systems whose outputs are grouped into a single block, involves the problem of the acquisition process of output measurements (continuous, sampled, delayed or not) and proposes a common framework for all possible cases. The second contribution proposes a filtered high gain observer on this same class of systems in order to reduce the sensitivity to measurement noise, in the case where the output is continuous and then in the case where the latter is sampled. The last contribution aims to extend the standard high gain synthesis for a large class of uniformly observable Multi-input / Multi-output systems with continuous output measurements. For each of these contributions, it has been shown that the observation error of each of the proposed observers converges exponentially towards zero in the absence of uncertainties in the system. All these contributions have been illustrated through several examples from different fields of study.

A major motivation for Lie group observers is their application as sensor fusion algorithms for an inertial measurement unit which can be used to estimate the orientation of a rigid-body. In the first part of this thesis we propose several types of nonlinear, deterministic, locally exponentially convergent, state observers for systems with all, or part, of their states evolving on the general linear Lie group of invertible matrices. Our proposed Lie group observer with full-state measurement is applicable to left-invariant systems on linear Lie groups and yields linear estimation error dynamics. We also propose a way to extend our full-state observer, to build observers with partial-state measurement, i.e., only a proper subset of the states are available for measurement. Our proposed Lie group observer with partial-state measurement is applicable when the measured states are evolving on a Lie group and the rest of the states are evolving on the Lie algebra of this Lie group. We illustrate our observer designs on various examples, including rigid-body orientation estimation and dynamic homography estimation. In the second part of this thesis we propose a nonlinear, deterministic state observer, for systems that evolve on real, finite-dimensional vector spaces. This observer uses the property of high-gain observers, that they are approximate differentiators of the output signal of a plant. Our new observer is called a composite high-gain observer because it consists of a chain of two or more sub-observers. The first sub-observer in the chain differentiates the output of the plant. The second sub-observer in the chain differentiates a certain function of the states of the first sub-observer. Effectiveness of the composite observer is demonstrated via simulation.

A major motivation for Lie group observers is their application as sensor fusion algorithms for an inertial measurement unit which can be used to estimate the orientation of a rigid-body. In the first part of this thesis we propose several types of nonlinear, deterministic, locally exponentially convergent, state observers for systems with all, or part, of their states evolving on the general linear Lie group of invertible matrices. Our proposed Lie group observer with full-state measurement is applicable to left-invariant systems on linear Lie groups and yields linear estimation error dynamics. We also propose a way to extend our full-state observer, to build observers with partial-state measurement, i.e., only a proper subset of the states are available for measurement. Our proposed Lie group observer with partial-state measurement is applicable when the measured states are evolving on a Lie group and the rest of the states are evolving on the Lie algebra of this Lie group. We illustrate our observer designs on various examples, including rigid-body orientation estimation and dynamic homography estimation. In the second part of this thesis we propose a nonlinear, deterministic state observer, for systems that evolve on real, finite-dimensional vector spaces. This observer uses the property of high-gain observers, that they are approximate differentiators of the output signal of a plant. Our new observer is called a composite high-gain observer because it consists of a chain of two or more sub-observers. The first sub-observer in the chain differentiates the output of the plant. The second sub-observer in the chain differentiates a certain function of the states of the first sub-observer. Effectiveness of the composite observer is demonstrated via simulation.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O setor fotovoltaico, devido ao seu grande crescimento nos Ãltimos anos, vem destacando-se significativamente diante de todas as outras fontes de energia renovÃveis e, por isso, tornou-se a terceira maior fonte limpa de geraÃÃo de energia elÃtrica do mundo. No Brasil, esse setor ainda nÃo possui uma relevÃncia na matriz energÃtica devido à tecnologia de conversores e de painÃis ser, na maioria das vezes, toda importada. Considerando a necessidade do desenvolvimento dessa tecnologia, este trabalho vem propor a pesquisa e a implementaÃÃo de um conversor CC/CC de alto ganho aplicado a sistemas fotovoltaicos, que tem como objetivo principal retirar a energia de um mÃdulo fotovoltaico e injetÃ-la em um barramento constante de corrente contÃnua. Um mÃdulo fotovoltaico à conectado na entrada do conversor de alto ganho com tensÃo de saÃda igual a 17 Vcc. Esse conversor eleva a sua tensÃo de entrada e injeta sua corrente de saÃda em um barramento constante de 311 Vcc, utilizando a busca do ponto de mÃxima potÃncia (MPPT). O protÃtipo implementado em laboratÃrio foi desenvolvido para uma potÃncia nominal de 100 W e nÃo possui capacitores eletrolÃticos, aumentando assim o tempo de vida Ãtil do conversor e permitindo incorporar o conversor ao mÃdulo fotovoltaico. O protÃtipo se mostrou robusto e de baixo custo, caracterÃsticas necessÃrias para um conversor aplicado a fontes renovÃveis de energia. O desempenho do protÃtipo, na busca do ponto de mÃxima potÃncia, superou as expectativas do autor, mostrando que um algoritmo bastante simples pode ser extremamente confiÃvel quando se opta pela configuraÃÃo de um conversor por mÃdulo. / The photovoltaic sector has been distinguishing itself from all other renewable energy sources, due to its large growth through the last years. For this reason, it has become the third major clean source of power generation worldwide. In Brazil, this sector still doesnât have great pertinence in the energy matrix, given the imported technology of converters and panels. Considering the demand to develop this technology, this paper propounds the research and implementation of a high gain DC/ DC converter applied to photovoltaic systems, which aims mainly to remove energy from a photovoltaic module and inject it into a DC constant bus. A photovoltaic module is connected to the input of the high gain converter, with an output voltage equals to 17 Vdc. This converter raises its input voltage and injects its output current at a constant 311 Vdc bus, using the maximum power point tracking (MPPT). The laboratory implemented prototype was designed for a rated power of 100W and it doesnât have electrolytic capacitors, thereby increasing the lifetime of the converter and also allowing the incorporation the converter to the photovoltaic module. The prototype had a strong and low cost performance, necessary characteristics for a converter applied to renewable energy sources. The prototype performance exceeded the authorâs expectations, in relation to the maximum power point tracking. Thus, a quite simple algorithm can be extremely reliable when choosing to configure a converter through a module.

In this work, an innovative approach for effective modeling of substrate integrated waveguide (SIW) devices is firstly proposed. Next, a novel substrate integrated waveguide power splitter is proposed to feed antenna array elements in series. This feed network inherently provides uniform output power to eight quadrupole antennas. More importantly, it led to a compact configuration since the feed network can be integrated inside the elements without increasing the overall array size. Its design procedure is also presented. Then, a series feed network was used to feed a novel compact omnidirectional antenna array. Targeting the 5G 26 GHz mm-wave frequency band, simulated results showed that the proposed array exhibits a broad impedance bandwidth of 4.15 GHz and a high gain of 13.6 dBi, which agree well with measured results. Its attractive features indicate that the proposed antenna array is well suitable for millimeter-wave wireless communication systems.