The analysis and design of passive broadband negative group delay (NGD) transmission line phase shifters is presented. By extending the metamaterial transmission line concept to include loss, a NGD unit cell is proposed. Phase shifters are supplemented with NGD unit cells to produce a flattened phase response significantly increasing phase bandwidths. The design methodology of a NGD phase shifter is presented with consideration of nominal phase, frequency, impedance, maximum insertion loss and bandwidth. The relation between gain, bandwidth and group delay signifies a fundamental design limitation and tradeoff. A significant application of NGD phase shifters for removing beam squint in series fed antenna arrays is discussed. Several NGD phase shifters are fabricated and experimentally verified in the UHF band upwards of 1 GHz using planar microstrip transmission lines loaded with passive surface mount RF components with both positive and negative phase shifts.

In this dissertation, the design, fabrication, and characterization of coplanar striplines, vias, and microstrip lines is investigated, from the point of view of developing interconnections for antenna-coupled infrared detectors operating in the 8- to 12-micron wavelength range. To our knowledge, no previous efforts have been made to study the performance of metallic-wire transmission lines at infrared frequencies. Both the design and fabrication of these structures present unique challenges. Because of attenuation and dispersion issues, the analytical formulas for transmission-line parameters that are valid below a few hundred GHz are not applicable in the infrared. Therefore, numerical modeling was performed to characterize the coplanar striplines and microstrip structures in terms of transmission-line parameters: characteristic impedance, attenuation constant and effective index of refraction. These parameters were extracted by fitting the computed impedance as a function of transmission-line length to the usual impedance transformation equation. The material properties used in the model are realistic, having been measured at the frequencies of interest by infrared ellipsometric techniques. The transmission-line parameters cannot be measured directly in the infrared, so experimental validation was carried out by measuring the response of a bolometer, which was connected to a dipole antenna by different lengths of both the coplanar and microstrip transmission lines. The modeled and measured responses for both types of transmission lines was in good agreement. A third type of signal-routing structure was also investigated, that of the vertical via, essentially a low-frequency connection that facilitates location of the bondpads away from the plane of the antenna. In the configuration studied, the vias pass vertically down through the SiO2 isolation layer and a groundplane, which provides electromagnetic isolation between the antenna and the structures that allow for signal-extraction from the bolometer. This type of interconnection will be useful for future detailed studies relating the angular antenna pattern to the spatial response of the antenna-coupled sensor.

<p> The microstrip transmission line has been theoretically analysed using conformal transformation and variational techniques. The variational method has been used to compute the line capacitance, characteristic impedance and guide wavelength of the following microstrip structures: (i) Microstrip transmission lines having negligible and finite strip conductor thickness. (ii) Microstrip transmission lines on two layer dielectric substrates having negligible and finite strip conductor thickness.</p><p> The total losses incurred in microstrip lines on semiconductor substrates have been included. An experimental technique (based on the Deschamps method) for measuring the characteristic impedance of microstrip lines through a lossy junction using a high precision microwave reflection bridge has been described. Measurements of the characteristic impedance of microstrip lines on intrinsic germanium substrates have been carried out at 9.38 GHz, and good agreement between the theoretical and experimental results have been obtained.</p> / Thesis / Master of Engineering (MEngr)

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No description available.

<p> This thesis addresses recent trends and developments of the adjoint-variable method (AVM) for microwave structures with the time-domain transmission-line modeling (TD-TLM) method. </p> <p> Design sensitivity analysis of high-frequency (HF) structures is concerned with estimating the sensitivity of the response with respect to the design parameters. This information is essential at different stages of the design cycle such as the optimization, tolerance analysis, and yield analysis. </p> <p> Traditional approaches of sensitivity calculations involve estimating the sensitivities thought fmite-difference approximations. They suffer from formidable simulation time, as the full-wave analysis of practical HF structure requires extensive computational time. For a structure with N design parameters, at least N+l system analyses are required to extract the design response and its sensitivities. The adjoint variable method, on the other hand, supplies the sensitivity information in a very efficient way. Using at most two system analysis, the algorithm provides the design responses and its sensitivities, regardless of the number of the design parameters. </p> <p> In this thesis two contributions have been achieved which aims at enhancing the efficiency of the TLM-A VM framework. The first contribution is a reformulation of the AVM. This reformulation results in casting both the original and the adjoint systems in mathematically identical forms. It is shown that both systems can thus be modeled using a single TLM simulator with the only difference in the excitation. The second contribution focuses on generalizing the A VM algorithm by employing it for more advanced TLM nodes. The compatibility of the symmetrical condensed node (SCN) with the AVM algorithm has been verified in previous work for a general 3-D problem. Here, this is extended to include the hybrid symmetrical condensed node (HSCN), which is more efficient in terms of memory saving and simulation time. The new approaches are all illustrated through sensitivity estimation of different waveguide structures. </p> / Thesis / Master of Applied Science (MASc)

Yes / In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna’s performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna’s radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results.

The multi-conductor lossy transmission-line model and finite element simulation tool are used to analyze the high-frequency attenuator and the DM transmission-line EMI filter. The insertion gain, transfer gain, current distribution, and input impedance of the filter under a nominal design are discussed. In order to apply the transmission-line EMI filter to power electronics systems, the performance of the filter under different dimensions, material properties, and source and load impedances must be known. The influences of twelve parameters of the DM transmission-line EMI filter on the cut-off frequency, the roll-off slope, and other characteristics of the insertion gain and transfer gain curves are investigated. The most influential parameters are identified. The current sharing between the copper and nickel conductors under different parameters are investigated. The performance of the transmission-line EMI filter under different source and load impedances is also explored. The measurement setups of the DM transmission-line EMI filter using a network analyzer have been discussed. The network analyzer has a common-ground problem that influences the measured results of the high-frequency attenuator. However, the common-ground problem has a negligible influence on the measured results of the DM transmission-line EMI filter. The connectors and copper strips between the connectors and the filter introduce parasitic inductance to the measurement setup. Both simulated and measured results show that transfer gain curve is very sensitive to the parasitic inductance. However, the insertion gain curve is not sensitive to the parasitic inductance. There are two major methods to reduce the parasitic inductance of the measurement setup: using small connectors and applying a four-terminal measurement setup. The transfer gain curves of three measurement setups are compared: the two-terminal measurement setup with BNC connectors, the two-terminal measurement setup with Sub Miniature version B (SMB) connectors, and the four-terminal measurement setup with SMB connectors. The four-terminal measurement setup with SMB connectors is the most accurate one and is applied for all the transfer gain measurements in this dissertation. This dissertation also focuses on exploring ways to improve the performance of the DM transmission-line EMI filter. Several improved structures of the DM transmission-line EMI filter are investigated. The filter structure without insulation layer can greatly reduce the thickness of the filter without changing its performance. The meander structure can increase the total length of the filter without taking up too much space and results in the cut-off frequency being shifted lower and achieving more attenuation. A prototype of the two-dielectric-layer filter structure is built and measured. The measurement result confirms that a multi-dielectric-layer structure is an effective way to achieve a lower cut-off frequency and more attenuation. This dissertation proposes a broadband DM EMI filter combining the advantages of the discrete reflective LC EMI filter and the transmission-line EMI filter. Two DM absorptive transmission-line EMI filters take the place of the two DM capacitors in the discrete reflective LC EMI filter. The measured insertion gain of the prototype has a large roll-off slope at low frequencies and large attenuation at high frequencies. The dependence of the broadband DM EMI filter on source and load impedances is also investigated. Larger load (source) impedance gives more attenuation no matter it is resistive, inductive or capacitive. The broadband DM EMI filter always has more high-frequency attenuation than the discrete reflective LC EMI filter under different load (source) impedances. / Ph. D.

Il existe aujourd'hui un enjeu sociétal majeur à s'intéresser à la propagation du son en milieu extérieur etnotamment, dans notre contexte, à diminuer l'incertitude sur l'estimation des niveaux sonores et améliorer ainsi laprécision des diverses analyses, du bureau d'étude à l'institut de recherche. Dans le cadre de l'acoustiqueenvironnementale, l'influence des conditions météorologiques sur la propagation acoustique en milieu extérieurpeut être importante. Il est donc nécessaire d'appréhender et de quantifier les phénomènes météorologiques demicro-échelles que l'on observe dans la couche limite atmosphérique.Dans ce but, le modèle météorologique de recherche de Météo-France (Meso-NH) a été utilisé. Après avoircomparé les résultats de ce modèle à très fine résolution (de l'ordre du mètre) à l'aide des bases de données de deuxcampagnes expérimentales (Lannemezan 2005 et la Station de Long Terme), il s'est avéré nécessaire de développercet outil en intégrant la prise en compte de la force de traînée des arbres. Dès lors, les résultats issus de Meso-NH surles champs de vent, de température et d'énergie cinétique turbulente aparraissent satisfaisants. Ces informationssont par la suite utilisées en données d'entrée du modèle de propagation acoustique.Le modèle acoustique temporel utilisé est basé sur la méthode Transmission Line Matrix (TLM). Sondéveloppement a été effectué dans le but d'être appliqué à la propagation acoustique en milieu extérieur : prise encompte du relief, de différents types de sol, des conditions atmosphériques, etc. La validation numérique de laméthode TLM, par comparaison avec d'autres modèles (analytique et numérique de type Equation Parabolique), apermis de montrer la pertinence de son utilisation dans le cadre de l'acoustique environnementale.Enfin, à l'aide de ces modèles, des niveaux sonores simulés sous différentes conditions de propagation(favorables, défavorables, homogènes) ont été comparés aux mesures in-situ réalisées lors de la campagneexpérimentale de Lannemezan 2005. Les résultats se sont avérés très satisfaisants au regard de la variabilité desphénomènes observés. Cependant, l'utilisation des champs issus d'un modèle micro-météorologique de type Meso-NH reste délicate du fait de la forte sensibilité du niveau sonore aux profils verticaux de célérité du son. L'étude defaisabilité sur une expérience plus complexe (la Station de Long Terme) est encourageante et, à condition de disposerd'importants moyens de calculs, elle permet de considérer la TLM comme une nouvelle méthode de référence etainsi, d'envisager d'élargir son domaine d'utilisation à d'autres applications. / Actually, it exists a major societal issue to be interested in outdoor sound propagation and specially, in our context, toreduce the uncertainty in noise levels estimation and thus to improve the analyses accuracy, from engineers toresearch institutes. The influence of meteorology on outdoor sound propagation is significant. It is thereforenecessary to understand and quantify the micro scales phenomena into the atmospheric boundary layer.In this way, the French research meteorological model (Meso-NH) has been used. After comparing resultsof this model at very fine resolution (~1 meter) to measurements issued from the databases of two experimentalcampaigns (Lannemezan 2005 and Long Term Monitoring Station: LTMS), it appeared necessary to develop this toolin order to take into account the drag force of the trees. Finally, the Meso-NH results for the wind, temperature andturbulent kinetic energy fields are satisfactory. Then, theses informations can be used as input data for acousticmodels.Our time domain acoustic model is based on Transmission Line Matrix method (TLM). Its development wasdone in order to be applied to outdoor sound propagation: taking into account topography, soil types, meteorologicalconditions, etc. The numerical validation of the TLM method, by comparison with other models (analytical andnumerical: Parabolic Equation), has shown the relevance of its use in the context of environmental acoustics.Finally, thanks to these models, simulated noise levels in different propagation conditions (downward,upward and homogeneous refraction conditions) were compared to in situ measurements carried out during theLannemezan 2005 experimental campaign. Satisfying results were obtained regarding the observed phenomenavariability. However, using the micro-meteorological model Meso-NH is difficult because of the strong acousticsensitivity to the vertical celerity profiles. A feasibility study on a more complex experience (LTMS) is encouragingand, provided having substantial computing resources, it permits to consider the TLM as an accurate method in thecontext of environmental acoustics.

Orientador: Sérgio Kurokawa / Banca: Afonso José do Prado / Banca: Lourenço Matias / Resumo: O objetivo deste projeto é o desenvolvimento de um modelo de linha de transmissão bifásica diretamente no domínio do tempo, que leve em consideração o efeito da freqüência sobre seus parâmetros longitudinais, utilizando os conceitos de variáveis de estado. Os parâmetros longitudinais, variáveis em relação à freqüência, serão aproximados por funções racionais, cujos pólos e resíduos deverão ser determinados por meio do algoritmo vector fitting. Em seguida, as funções racionais que descrevem o comportamento dos parâmetros longitudinais serão associadas com um circuito elétrico equivalente, que será inserido em cada um dos circuitos π, constituindo uma grande quantidade de cascata de circuitos π. O modelo será utilizado para a realização de simulações de transitórios resultantes das operações de manobras e chaveamentos que ocorrem em uma linha bifásica com plano de simetria vertical. Os resultados serão comparados com os resultados obtidos com programas computacionais do tipo EMTP (cascata de circuitos π inserida no EMTP). Ao término do projeto teremos a nossa disposição um modelo de linha de transmissão que não necessita do uso de simuladores do tipo EMTP. / Abstract: The objective of this work is to implement a computational model of two-phase transmission line in time domain taking into account its frequency dependent longitudinal parameters. The line is represented through a cascade of π circuits and the frequency dependence of the longitudinal parameters is approximated by a rational functions that can be associated with an equivalent circuit representation and this equivalent circuit is inserted in each π circuit. After that the cascade is described through state equations. Validating the model, a frequency dependent two-phase line is represented by a cascade of π circuits. The model will be use for typical switching transients in a two-phase transmission line with a vertical symmetrical plan. The simulations were carried out using state space techniques and an EMTP program (in this case, the cascade was inserted in the EMTP program). It is observed that the simulation results obtained with state space representation are in agreement with those results obtained with EMTP. / Mestre