Disertacijoje sprendžiama spiralinių ir meandrinių lėtinimo sistemų su periodiniais netolygumais modeliavimo metodų tobulinimo ir jų tobulesnių konstrukcijų paieškos problema. Pagrindiniai tyrimo objektai – nevienalytės periodinės lėtinimo sistemos ir jų modeliai bei analizės metodai. Darbo tikslas yra tobulinti sudėtingas turinčias periodinių netolygumų spiralines ir meandrines lėtinimo sistemas ir ištirti jų analizės metodus, siekiant atskleisti nevienalyčių lėtinimo sistemų savybes ir jų automatizuoto projektavimo galimybes. / There are investigated issues of modeling techniques improvement and investigation of improved design of helical and meander slow-wave systems with periodical inhomogeneities in the dissertation. Objects of research – models of slow-wave systems with periodical inhomogeneities and their methods of investigation. Aim of the work – improvement of sophisticated helical and meander slow-wave systems with periodical inhomogeneities and investigation of their methods of analysis, in order to reveal general characteristics of inhomogeneous slow-wave systems and capabilities of using computer-aided design.

There are investigated issues of modeling techniques improvement and investigation of improved design of helical and meander slow-wave systems with periodical inhomogeneities in the dissertation. Objects of research – models of slow-wave systems with periodical inhomogeneities and their methods of investigation. Aim of the work – improvement of sophisticated helical and meander slow-wave systems with periodical inhomogeneities and investigation of their methods of analysis, in order to reveal general characteristics of inhomogeneous slow-wave systems and capabilities of using computer-aided design. / Disertacijoje sprendžiama spiralinių ir meandrinių lėtinimo sistemų su periodiniais netolygumais modeliavimo metodų tobulinimo ir jų tobulesnių konstrukcijų paieškos problema. Pagrindiniai tyrimo objektai – nevienalytės periodinės lėtinimo sistemos ir jų modeliai bei analizės metodai. Darbo tikslas yra tobulinti sudėtingas turinčias periodinių netolygumų spiralines ir meandrines lėtinimo sistemas ir ištirti jų analizės metodus, siekiant atskleisti nevienalyčių lėtinimo sistemų savybes ir jų automatizuoto projektavimo galimybes.

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Yes / The main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green’s functions in the spectral domain. In order to validate the computing method and evaluated Matlab® calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction. / This work is part of the POSITION-II project funded by the ECSEL joint Undertaking under grant number Ecsel-7831132-Postitio-II-2017-IA,www. position-2.eu and partly funded by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020- UIDP/50008/2020. This work was also supported in part by the DGRSDT (General Directorate of Scientific Research and Technological Development) - MESRS (Ministry of Higher Education and Scientific Research), Algeria, and RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE).

The use of full wave electromagnetic modeling and simulation tools allows for accurate performance predictions of unique RF structures that exhibit multi-dimensional scales. Full wave simulation tools need to cover the broad range of frequency including RF and terahertz bands that is focused as RF technology is developed. In this dissertation, three structures with multi-dimensional scales and different operating frequency ranges are modeled and simulated. The first structure involves nanostructured solar cells. The silicon solar cell design is interesting research to cover terahertz frequency range in terms of the economic and environmental aspects. Two unique solar cell surfaces, nanowire and branched nanowire are modeled and simulated. The surface of nanowire is modeled with two full wave simulators and the results are well-matched to the reference results. This dissertation compares and contrasts the simulators and their suitability for extensive simulation studies. Nanostructured Si cells have large and small dimensional scales and the material characteristics of Si change rapidly over the solar spectrum. The second structure is a reconfigurable four element antenna array antenna operating at 60 GHz for wireless communications between computing cores in high performance computing systems. The array is reconfigurable, provides improved transmission gain between cores, and can be used to create a more failure resilient computing system. The on-chip antenna array involves modeling the design of a specially designed ground plane that acts as an artificial magnetic conductor. The work involves modeling antennas in a complex computing environment. The third structure is a unique collar integrated zig-zag antenna that operates at 154.5 MHz for use as a ground link in a GPS based location system for wildlife tracking. In this problem, an intricate antenna is modeled in the proximity of an animal. Besides placing a low frequency antenna in a constricted area (the collar), the antenna performance near the large animal body must also be considered. Each of these applications requires special modeling details to take into account the various dimensional scales of the structures and interaction with complex media. An analysis of the challenges and limits of each specific problem will be presented.

Au début du 21ème siècle, l'innovation dans le domaine des instruments de musique se fait surtout par le biais de la synthèse sonore, via des synthétiseurs et des ordinateurs. Cependant, si ces instruments permettent une création presque infinie de sons nouveaux, l'interaction entre le musicien et son instrument est bien plus pauvre qu'avec un instrument mécanique, ce qui provoque une perte d'expressivité musicale et réduit l'utilité d'une grande maîtrise du geste instrumental. Dans le but d'innover tout en conservant ce geste musical, cette thèse propose d'appliquer le contrôle actif aux instruments à vent, en particulier, sur le trombone muni d'une sourdine active et sur la clarinette basse. Son objectif est de modifier les caractéristiques des résonances des instruments à vent afin d'en modifier le son produit (hauteur, timbre) et la jouabilité. Les effets des modifications apportées aux instruments, lors de l'utilisation de deux méthodes de contrôle actif, sont observés sur l'impédance d'entrée des instruments, sur leur fonction de transfert et sur le son rayonné. Un contrôle actif par feedback simple n'utilisant que des gains et des déphasages est appliqué à la sourdine. Cela permet de modifier la fréquence et l'amortissement de sa résonance, avec pour conséquence de modifier l'impédance d'entrée du trombone, et pour l'instrumentiste de faire varier sa jouabilité. Si ce premier contrôle est simple, il ne permet pas de contrôler efficacement un système à plusieurs degrés de liberté. Le deuxième contrôle implémenté est le contrôle actif modal. Il permet, à partir d'un modèle du système à contrôler, de modifier de manière ciblée les paramètres modaux de ses résonances (amortissement et fréquence). Il est appliqué en simulation à un modèle de clarinette puis validé expérimentalement sur une "clarinette basse simplifiée". Il permet d'importantes modifications des résonances, entrainant des changements notables dans le son et l'impédance d'entrée. / The main focus of innovation in musical instrument making in the early 21st century has been sound synthesis using computers or stand-alone electronic synthesisers. However, while these tools enable the creation of a near-infinite range of new sounds, the interaction between the musician and their instrument is much weaker than with a conventional acoustical instrument. This results in a loss of musical expression and reduces the use of musical gesture. With the aim of innovating while keeping the influence of musical gesture, this thesis proposes to apply active control to musical wind instruments. In particular, active control is applied to a trombone equipped with a specially designed mute and to a bass clarinet. The aim of this work is to modify each instrument's resonance characteristics in order to change its radiated sound (pitch, timbre) and playability. The effects of two control methods on the input impedance, transfer function and radiated sound of the instruments are studied. First, a feedback control involving gains and phase shifting is applied to the trombone mute. It allows significant modification of both the frequency and the damping factor of the mute's resonance. The effects of the mute on the trombone's input impedance and playability are studied. This control is simple, but it is not efficient with more complex systems. Second, a modal control is implemented. Using a model of the system, modal active control allows the modal parameters (frequency, damping) of the system's resonances to be modified in a targeted manner. It is first applied to a modelled clarinet, then experimentally validated with a "simplified bass clarinet". Significant independent modifications of the resonances are obtained, as well as noticeable alterations of the sound and input impedance of the instrument.

Yes / In this paper, we present an analytical study for the investigation of the effects of the magnetoelectric elements of a reciprocal and nonreciprocal bianisotropic grounded substrate on the input impedance, resonant length of a dipole antenna as well as on the mutual coupling between two element printed dipole array in three configuration geometries: broadside, collinear and echelon printed on the same material. This study examines also the effect of the considered bianisotropic medium on the electric and magnetic field distributions that has been less addressed in the literature for antenna structures. Computations are based on the numerical resolution, using the spectral method of moments, of the integral equation developed through the mathematical derivation of the appropriate spectral Green’s functions of the studied dipole configuration. Original results, for chiral, achiral, Tellegen and general bi-anisotropic media, are obtained and discussed with the electric and magnetic field distributions for a better understanding and interpretation. These interesting results can serve as a stepping stone for further works to attract more attention to the reciprocal and non-reciprocal Tellgen media in-depth studies.

Magistro baigiamajame darbe tiriamos nevienalyčių plačiajuosčių periodinių sistemų užtvarinės savybės. Aptariamos periodinės sistemos ir jų charakteristikų skaičiavimo metodai. Nevienalyčių periodinių savybių tyrimui panaudoti du modeliai. Pradžioje nagrinėjamos periodinės ilgosios linijos savybės, vėliau taikomas spiralinės sistemos modelis. Modelių analizė atliekama klasikiniu, matriciniu ir daugialaidžių linijų metodais. Taikomas kompiuterinis modeliavimas. Sudarytos įėjimo varžos, perdavimo ir lėtinimo koeficientų, vėlinimo laikų bei pereinamosios charakteristikos skaičiavimo programos. Parodyta, kad linijos su periodiniais netolygumais įgyja užtvarinio filtro savybes, kurios ryškėja, didėjant sistemos nevienalytiškumui. / In order to reveal general properties of the structures, containing periodical inhomogeneities, the inhomogeneous electromagnetic line and the inhomogeneous helical retard structure are considered. The overview of periodical systems and methods of their analysis are presented. The structures, containing periodical inhomogeneities, are analyzed using classical, matrix and multiconductor line methods. The programs for calculation of line input impedance, transfer coefficient, delay coefficient and width of the stop-band are developed. The results show that the stop–band appears due to periodical inhomogeneities and the width of the stop-band and the attenuation in it depend on intensities of periodical inhomogeneities.

The Archimedean spiral antenna is well-known for its broadband characteristics with circular polarization and has been investigated for several decades. Since their development in the late 1950's, establishing an analytical expression for the characteristics of spiral antenna has remained somewhat elusive. This has been studied qualitatively and evaluated using numerical and experimental techniques with some success, but many of these methods are not convenient in the design process since they do not impart any physical insight into the effect each design parameter has on the overall operation of the spiral antenna. This work examines the operation of spiral antennas and obtains a closed-form analytical solution by conformal mapping and transmission line model with high precision in a wide frequency band. Based on the analysis of spiral antenna, we propose two novel design processes for the stripline-fed Archimedean spiral antenna. This includes a stripline feed network integrated into one of the spiral arms and a broadband tapered impedance transformer that is conformal to the spiral topology for impedance matching the nominally-high input impedance of the spiral. A Dyson-style balun located at the center facilitates the transition between guided stripline and radiating spiral modes. Measured and simulated results for a probe-fed design operating from 2 GHz to over 20 GHz are in excellent agreements to illustrate the synthesis and performance of a demonstration antenna. The research in this work also provides the possibility to achieve conformal integration and planar structural multi-functionality for an Unmanned Air Vehicle (UAV) with band coverage across HF, UHF, and VHF. The proposed conformal mapping analysis can also be applied on periodic coplanar waveguides for integrated circuit applications.

Ce travail est une étude de caractérisation de différents composants du réseau basse tension (BT) français dans la bande de fréquence utilisée par les courants porteurs en ligne en bande étroite entre 9 kHz et 500 kHz. L’objectif est de permettre une compréhension approfondie de la propagation du signal CPL dans le réseau BT français. L’approche ascendante est choisie. Elle consiste en la caractérisation du réseau à partir de la caractérisation de chaque composant le constituant. Deux composants essentiels du réseau BT ont été caractérisés : les câbles d’énergie et les installations des clients. Dans la première partie, différentes technologies de câbles de distribution et de branchement ont été caractérisées expérimentalement. Deux modèles ont été choisis, un premier modèle dit ligne simple (LS) qui ne prend pas en compte le couplage et un deuxième modèle dit ligne couplée (LC) plus complet qui prend en compte le couplage inductif et capacitif entre les lignes de transmission des câbles. Dans la deuxième partie, on s’est intéressé à l’obtention des impédances d’entrée des installations des clients vues par le réseau BT. Ces impédances ont été obtenues à partir de la caractérisation du câble électrique domestique ainsi que celle de différents appareils domestiques parmi les plus présents dans les installations. Pour ces différentes caractérisations, trois méthodes expérimentales ont été conçues et mises au point. Une étude paramétrique a été réalisé pour évaluer l’influence des longueurs des câbles ainsi que les valeurs des impédances connectées aux extrémités des lignes de transmission de ces câbles sur l’atténuation, le couplage et l’impédance d’accès. / This work presents the characterization of different components of the French Low Voltage (LV) network in the frequency band used by the narrowband power line communication (PLC) between 9 kHz and 500 kHz. The aim of this work is to provide a deeper understanding of the propagation of the PLC signal in the French LV network. For this, the bottom-up approach is used. This approach consists in LV network characterization starting from the characterization of each component of this LV network. Two essential components of the LV network have been characterized: energy cables and customer installations. In the first part, different distribution and connection cable technologies have been experimentally characterized.Two models have been chosen: a first model called LS consisting on the characterization of cables without taking into account the coupling and a second one more complete called LC which, takes into account the inductive and capacitive coupling between the transmission lines of the cables. In the second part, the work focused on obtaining the input impedance of the customer installations seen by the LV network. These impedances were obtained from the characterization of the domestic electrical cable as well as various domestic appliances among the most present in the installations. Finally, the results of both parts allowed to make a parametric study of the influence of cable lengths and the impedance values connected to the ends of the transmission lines of these cables on attenuation, coupling and access impedances.