Le travail de recherche proposé dans ce manuscrit consiste à modéliser le rayonnement électromagnétique de conducteurs filaires. En effet l’estimation du rayonnement est un enjeu majeur et l’utilisation de modèles exacts nous semble nécessaire. On propose donc dans ce mémoire une approche analytique qui permet de quantifier les niveaux de champs électromagnétiques rayonnés par les systèmes filaires. Dans un premier temps nous proposons un modèle analytique du calcul du champ électromagnétique rayonné par un système filaire basé sur un développement approfondi des équations de Maxwell. Ce formalisme est issu de la formulation intégrale du potentiel vecteur émis par une antenne filaire dont on supposera connu la distribution de courant. Le modèle analytique ainsi obtenu permet d’estimer aisément les champs sans avoir besoin de discrétiser ni le support de transmission ni l’espace d’observation. Pour enrichir notre modèle nous avons ensuite envisagé les cas où la distribution du courant le long des conducteurs était issu, soit de la théorie des lignes soit d’une simulation numérique basée sur la théorie des antennes, soit de mesures. Dans le cas où c’est la théorie des lignes qui est à la base de la détermination des courants distribués, nous proposons un formalisme analytique du champ électromagnétique rayonné basé uniquement sur la seule connaissance des courants et de leurs dérivées aux extrémités des conducteurs. Nous avons également montré que ce formalisme s’extrapole aisément au cas d’un réseau multifilaire. Dans le cas où la théorie des antennes ou des mesures sont à la base de la connaissance des courants distribués, on identifie ce courant par quelques pôles et résidus grâce à la méthode d’identification Matrix Pencil (MP). Le champ électromagnétique rayonné s’exprime alors par une série finie de termes intégrales. Ce formalisme reste analytique et présente l’avantage d’être adapté aux approches paramétriques et d’optimisations. Nos travaux de recherche ouvrent des perspectives de reconstruction de la distribution du courant par Matrix Pencil à partir de la connaissance du courant et de ses premières dérivées spatiales aux seules extrémités des conducteurs. Le champ électromagnétique rayonné sera alors déduit de notre modèle. / The research presented in this thesis is focused on the modelling of electromagnetic radiation from thin-wire configuration. The radiation assessment is one of the most important issues which strongly requires an accurate modelling. In this work, an analytic approach to evaluate electromagnetic field radiated from thin-wire structure sis proposed. In the first part, we propose an analytical model for calculation of the electromagnetic fields from wire structure derived from the Maxwell equations. This formalism arises from the integral formulation of the magnetic vector potential due to a known current distribution along a wire antenna. The analytical model enables one to readily calculate the fields without requirement of wire structure discretization or involving the propagation effect over the domain of interest. In order to improve the model, we subsequently analyze cases where the current distribution along the conductors is known, either obtained by using the transmission line theory, by numerical simulations based on the antenna theory, or by measurements. On the basis of the known current and its derivative at the ends of a two-wire configuration, obtained by using the transmission line theory, the proposed approach yields an analytical formalism for determination of the radiated electromagnetic field. This analytical formalism is readily extended to multiple wires structures, as well. Once the current distribution is determined by using the antenna theory, the proposed method extracts the corresponding poles and residues by using the Matrix Pencil Method (MPM). In this case, the radiated electromagnetic field is formulated just by few integral terms. The main advantage of the analytical formulation within the framework of the proposal approach is that the method is very suitable for parametric and optimisation studies. This research should be considered as an opener to the subject related to reconstruction of the current distribution by using the Matrix Pencil method (MPM) only based on the current and its first derivative at the wire structure ends. Consequently the radiated electromagnetic field may be subsequently readily calculated by using theproposed analytical model.

This thesis focuses mostly on investigating different potential applications of meta-transmission line (TL), particularly composite right/left handed (CRLH) TL, and analyzing some new phenomena and applications of meta-TL, mostly left-handed (LH) TL. Realization principle will also be studied.   First, the fundamental electromagnetic properties of propagation in the presence of left-handed material (LHM) are illustrated. The transmission line approach for LHM design is described together with a brief review of the transmission line theory. As a generalized model for LHM TL, CRLH TL provides very unique phase response, such as dual-band operation, bandwidth enhancement, nonlinear dispersion, and the existence of critical frequency with zero phase velocity. Based on these properties, some novel applications of the existing CRLH transmission lines are then given, including a notch filter, a diplexer, a broadband phase shifter, a broadband balun, and a dual band rat-ring coupler. In the design of notch filters and diplexers, CRLH TL shunt stub is utilized to provide high frequency selectivity due to the existence of critical frequency with zero phase velocity. The proposed wideband Wilkinson balun, which comprises of one section of conventional transmission lines and one section of CRLH-TL, is shown to have a 180°±10° bandwidth of 2.12 GHz centered at 1.5 GHz. In the analysis of the dual band rat-ring couplers, a generalized formulation of the requirements about impedances and electrical length of the branches are derived, and as an example, a compact dual-band rat-race coupler is designed utilizing the balanced CRLH TL. Furthermore, a low pass filter is also proposed and designed based on a single (epsilon) negative coplanar waveguide (CPW).Various principles to realize meta-transmission lines are investigated. The main conclusions are listed below:Ÿ         Dual composite right/left handed (D-CRLH) transmission line, which is the dual structure of conventional CRLH TL, shows opposite handedness in the high frequencies and low frequencies with CRLH TL. Meanwhile, in the practical implementation, D-CRLH TL always shows a sharp stopband. A notch filter and a dual-band balun are designed based on D-CRLH TL. Ÿ         The lattice type transmission line (LT-TL) shows the same magnitude response with the conventional right-handed (RH) TL, but a constant phase difference in the phase response over a wide frequency band. A wideband rat-race coupler is proposed as an application of the LT-TL. Ÿ         Finger-shorted interdigital capacitors (FSIDCs) are analyzed and it is shown that FSIDC alone can act as a left-handed transmission line. The value of the reactive elements (inductors and capacitors) in the equivalent circuit model is determined by the dimensions of FSIDC. The relationship between them is analyzed.Later, transmission line loaded with negative-impedance-converted inductors and capacitors is illustrated as the first non-dispersive LH transmission line. The design of a negative series impedance converter is given in detail and a wideband power divider is designed as a potential application of the newly proposed meta-transmission lines in is also given. The final part of the thesis focuses on the study of microstrip lines loaded with complementary split ring resonators (SRRs). An equivalent circuit is made for this structure. The circuit model is verified by the experimental results of cases with different periodic lengths. Thereafter, a meander line split ring resonator (MLSRR) is presented. It shows dual band property and the miniature prototypes of complementary MLSRR loaded transmission lines are fabricated. By comparing the resonance frequencies of complementary MLSRR and multiple SRR, it is shown that the complementary MLSRR is very compact. C-MLSRR is applied in rejecting unnecessary frequencies in the ultra wideband antennas. / QC 20100720

Cette thèse présente, dans un premier temps, une nouvelle approche pour traiter les lignes de transmission, appelée la Théorie des Lignes de Transmission Améliorée et Modifiée (TLTAM). Cette extension du formalisme classique de la théorie des lignes de transmission est directement dérivée des équations de Maxwell et ne se limite pas à la seule prise en compte du mode transverse électromagnétique (TEM). Tout en conservant la simplicité du formalisme classique, cette extension aboutit à la définition de paramètres linéiques évolués et associés au mode antenne de la ligne de transmission. Cette solution présente l’avantage d’être compatible avec les noyaux de calcul existants, tout en palliant certaines limitations de la théorie des lignes de transmission (TLT) classique. LA TLTAM est tout d’abord définie pour le cas élémentaire d’une ligne de transmission à conducteur unique. Elle est ensuite généralisée au cas d’un nombre quelconque de conducteurs. Les matrices de paramètres linéiques correspondants sont alors définies. Les capacités de cette nouvelle théorie sont démontrées et validées au moyen de confrontations avec la solution directe des équations de Maxwell et de résultats de mesure. Dans un deuxième temps, le traitement d’une ligne de transmission multiconducteur située à distance d’un plan de référence conducteur est effectué au moyen d’une nouvelle approche désignée sous le nom de Théorie des Lignes de Transmission à Double Référence Intégrée (TLTDRI). Cette approche permet de simplifier l’évaluation des paramètres linéiques du faisceau en scindant le problème initial en deux sous-ensembles de lignes de transmission couplées. Le premier sous-ensemble est composé d'un fil conducteur du faisceau choisi arbitrairement et le plan de référence et constitue le sous-ensemble externe. Le deuxième sousensemble est composé uniquement des fils conducteurs du faisceau, en l’absence du plan de référence et constitue un sous-ensemble interne dont la référence locale est le fil choisi précédemment. On montre alors que seul le sous-ensemble externe nécessite le calcul de paramètres linéiques évolués associés à TLTAM. Le calcul des paramètres linéiques dans le système à référence unique constituée par le plan de référence, est reconstitué à partir de formules de passage permettant leur expression à partir des paramètres linéiques des deux sousensembles. Cette approche est validée et ses résultats sont en très bon accord avec ceux fournis par un calcul numérique direct des équations de Maxwell ainsi que ceux de la TLTAM. Elle permet une simplification très significative du traitement de l’interaction entre le faisceau de câble et la structure conductrice de référence. / This thesis presents, in a first step, a new approach to deal with transmission lines called the Modified Enhanced Transmission Line Theory (METLT). This extension of the classical formalism of the transmission line theory (TLT) is directly derived from Maxwell's equations without the restriction to the transverse electromagnetic (TEM) mode. This extension leads to the definition of enhanced per-unit-length (p.u.l.) parameters taking into account the antenna mode of the transmission line, while it keeps the simplicity of the classical formalism. This solution presents the advantage of being compatible with the existing TLT solvers while overcoming some limitations of the classical TLT. The METLT is firstly developed for the simple case of a single conductor transmission line. It is then generalized to the case of any number of conductors. The corresponding matrices of the p.u.l. parameters are then calculated. The capabilities of this new theory are demonstrated and validated by the means of comparisons with results obtained through a rigorous resolution of Maxwell's equations and measurements results. In a second step, a multi-conductor transmission line sufficiently far from the reference ground plane is assessed through a new approach called: Embedded Double Reference Transmission Line Theory (EDRTLT). This approach allows the simplification of the calculation of the harness p.u.l. parameters by splitting the first set of wires above a ground plane into two subsets of coupled transmission lines. The first subset consists in a conducting wire chosen arbitrarily and the reference ground plane and forms the external subset. The second subset consists only in the conducting wires of the harness, in the absence of the ground plane, and forms an internal subset which local reference is the wire chosen previously. We show that only the external subset requires the calculation of the enhanced p.u.l. parameters with the METLT. The calculation of the harness p.u.l. parameters in the system with a single reference, which is the ground plane only, is made through transformation formulae that allow their extraction from the p.u.l. parameters of the two subsets. This approach is validated and its results are in a very good agreement with those obtained by a rigorous resolution of Maxwell's equations and those of the METLT. It allows a great simplification to assess the interaction between the harness and the reference conducting structure.

This work focuses on a search of available literature on the theory of transmission lines and verify the possibility of simulation processes on these lines using a suitable simulation program. Initially, for the introduction to the parameters and the phenomenon that characterize the line and are important for understanding the issue. These parameters are then measured and compared with traces from the simulation in program PSpice. In another part of the work, the reader is familiar with the basics of reflectometry and fault detection capabilities on transmission lines with the basic reflectometry methods TDR and FDR, as well as with other methods of OTDR, MSR, and PD-FDR. For the TDR, FDR and MSR methods were made experimental measurements with a view to determining the position of the various types of faults on the tested leadership.

Pour répondre aux exigences réglementaires de plus en plus sévères au regard des émissions de CO2, l'industrie automobile voit poindre l'émergence des chaînes de traction électrique dans des structures véhicules en matériaux composites. Dans ce manuscrit, le point de vue du constructeur automobile est considéré. En effet, pour répondre aux exigences automobiles en compatibilité électromagnétique (CEM) pour l'homologation et la protection de la santé des personnes vis-à-vis des champs électriques et magnétiques, le blindage électromagnétique est l'une des solutions de conception les plus utilisées. Afin d'évaluer les meilleurs concepts à moindre coût et réduire autant que possible les délais de prototypage, la modélisation et la simulation numérique doivent encore se développer et être déployées. Les chapitres de ce manuscrit illustrent, étape par étape, la modélisation, la simulation et la validation expérimentale du blindage d'une architecture de chaîne de traction électrique. Dans un premier temps,l'influence d'un matériau composite à savoir l'époxy renforcé en fibres de carbone est étudié sur les émissions conduites et rayonnées en présence d'un câble blindé. Dans un deuxième temps, une méthodologie de modélisation des câbles blindés et des raccords de masse est proposée dans un environnement électromagnétique où la théorie des lignes de transmission classique ne s'applique pas. Pour valider les deux précédentes parties, des bancs de mesure sont proposés et développés. Les résultats expérimentaux sont comparés à la simulation numérique. La dernière partie considère une chaîne de traction électrique simplifiée en présence de boîtiers métalliques, de câbles de puissance blindés, de raccords de blindage et de raccords de masse dans une structure multi-matériaux dans la bande de fréquences 10 kHz - 300 MHz. Les émissions conduites et rayonnées sont analysées en portant une attention particulière à la perturbation de la réception radio. / To reach the increasingly stringent regulatory requirements for CO2 emissions, the automotive industry is improving the electric powertrains in car bodies with composite materials. In this thesis report, the point of view of the car manufacturer is considered. The electromagnetic shielding is one of the most important design solutions to respect the electromagnetic compatibility (EMC) requirements for the homologation and the protection of human health with respect to electrical and magnetic fields. In order to evaluate the best concepts at lower costand to minimize prototyping delays, modeling and numerical simulation still need to be developed and deployed.The chapters of this thesis report illustrate, step by step, the modeling, the simulation and the experimentalvalidation of the shielding applied to an electric powertrain. In a first step, the influence of a composite material such as the carbon fiber reinforced epoxy is studied on the conducted and the radiated emissions in presence of a shielded cable. In a second step, a methodology to model shielded cables and the grounding connectionsis proposed in an electromagnetic environment where classical transmission line theory cannot be applied. Tovalidate the two previous parts, measurement setups are proposed and developed. The experimental results arecompared with the numerical simulation. The last part considers a simplified electric powertrain with metal housings, shielded power cables, shielding connections and grounding connections in a multi-material structurein the 10 kHz - 300 MHz frequency band. The conducted and radiated emissions are analyzed with a particular attention to the disturbance of the radio reception.

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.

Transients encountered by transformers in power stations during normal operation can have complex oscillatory overvoltages containing a large spectrum of frequency components. These transients can coincide with the natural frequencies of the transformers windings, leading to voltages that can be greater or more severe than the current factory proof tests. This may lead to insulation breakdown and catastrophic failures. Existing lumped parameter RLCG transformer models have been proven to be less accurate for very fast transient overvoltages (VFTO) with frequencies over 1 MHz. A white box model for transient analysis of transformer windings has been developed using Multiconductor Transmission Line (MTL) Theory. This model enables the simulation of natural frequencies of the transformer windings up to frequencies of several MHz, and can be used to compute voltages between turns by representing each turn as a separate transmission line. Both continuous and interleaved disk windings have been modelled and a comparison and validation of the results is presented. / May 2017