Thesis (PhD)--Stellenbosch University, 1994. / ENGLISH ABSTRACT: An artificial chiral medium can be made by embedding metal helices (chiral or handed structures) with random orientation inside au achiral hnst medium. The electromagnetic behaviour of such artificial chiral media can be explained by an additional (to p. and t') constitutive parameter, the chirality parameter e. Chiral media have certain special properties of which optical activity is the most prominent. Optical activity is the term used to describe the rotation of the polarization plane of a linearly polarized wave as it travels through a chiral medium. The chirality parameter is directly linked with this rotation. The reflection and the transmission coefficients from a chiral slab are well known in terms of the constitutive parameters and the thickness of the sample. In the thesis a set of .inversion equations are derived that can be used to determine the constitutive parameters (p., £, e) of a chiral medium from the measured S-parameters 811, S21x and S2l'jJ (Le. the reflection and co- and cross-polarized transmission coefficients respectively). An accuracy analysis of the measurement method is made. This is done by using the first order partial derivatives of the inversion equations. A sensitivity analysis is done on the inversion equations and the results are in an analytical form. This makes it possible to determine the contribution of each of the measurement errors to the total expected error. A statistical root mean square method is used to predict the expected error in the measured constitutive parameters. Several artificial chiral samples are measured and an accuracy analysis done on the measurements. The inaccuracy of the method of inversion for low loss samples that are multiples of half a wavelength thick is illustrated by example and explained by the sensitivity analysis. The free-space system (11-17 GHz) used to measure the S-parameters is described in detail. The radiation patterns of the focused lens antennas are measured and compared to those obtained from two theoretical models. A free-space calibration procedure is developed and the dispersion in the focal region of the antennas incorporated into it. The results from different combinations of calibration standards are compared and related to the idea of minimum sensitivity calibration. The possible use of an artificial chiral medium as a microwave absorber is also discussed. / AFRIKAANSE OPSOMMING: Kunsmatige kirale media kan gemaak word deur metaalhelikse lukraak te orienteer in 'n mekirale (bv. diEHektriese) medium. Die mikrogolfeienskappe van kirale media kan toegeskryf word aan die anti-simmetrie van die mikroskopiese insluitings. 'n Voorwerp word as kiraal beskryf indien dit nie deur translasie of rotasie op die spieelbeeld daarvan gepas kan word nie. Die menslike hand is 'n goeie voorbeeld van so 'n kirale struktuur. Die elektromagnetise eienskappe van 'n kunsmatige kirale medium kan beskryf word deuT 'n addisionele (tot j.t en E) samestellingsparameter, die kiraliteitsparameter ~. Kirale media het verskeie ongewone eienskappe waarvan opti~se aktiwiteit waarskynlik die prominentste is. Optiese aktiwiteit beskryf die verskynsel waar die polarisasierigting van 'n lineer-gepolariseerde golf geroteer word terwyl dit deur 'n kirale medium beweeg. 'n Direkte verband bestaan tussen die rotasie en die kiraliteitsparameter. Die weerkaats- en transmissiekotHfisiente van 'n kirale plaat is bekend in terme van die samestellingsparameters (j.t, f. en {) en die dikte van die plaat. In die tesis word 'n ste1 inversievergelykings afgelei wat gebruik kan word om die samestellingsparameters van 'n kirale medium te bepaal vanuit die gemete weerkaats- en transmissiekoeffisiente, Sl1, S'lIz en SUg. (S213/ is die kruis-gepolariseerde komponent van die transmissiekoeffisient wat 'n aanduiding van die rotasie gee.) ,n Analise word gedoen op die akkuraatheid waarmee metings uitgevoer kan word. Dit word gedoen deur gebruik te maak van die eerste orde parsHHe afgeleide van die inversievergelykings. 'n Sensitiwiteitsanalise van die inversievergelykings word gedoen en in 'n analitiese vurm aangebied. Die vorm maak dit moontlik om die bydrae van elke meetfout in S11, S2l:c en S21'!J tot die totale meetfout in p., € en ete bepaal. 'n Statistiese metode (wortel gemiddelde kwadraat) word gebruik om die verwagte foutwaardes in die gemete samestellingsparameters te bepaal. Verskeie kunsmatige kirale media word gemeet en 'n analise word gedoen op die akkuraatheid waarmee elk gemeet is. Die onakkuraatheid van die inversiemetode vir plate met lae verliese en wat veelvoude van 'nhalwe golflengte dik is, word getoon deur middel van 'n sensitiwiteitsanalise. Die vryeruimte meetstelsel (11-17 GHz) wat gebruik word om die weerkaats- en transmissiekoeffisH~ nte te meet, word breedvoerig bespreek. Die gemete stralingspatrone van die gefokusseerde lens antennes word vergelyk met teoreties bepaalde waardes. 'n Vryeruimte kalibrasietegniek word ontwikkel en die gemete dispersie in die fokusgebied word daarby ingesluit. Die resultate, soos verkry van verskillende kalibrasiestandaarde, word vergelyk en in verband gebring met die tegniek van kalibrasie-met-minimum-sensitiwiteit. Ten slotte word die moontlike gebruik van kunsmatige kirale media as mikrogolfabsorbeerders ondersoek.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Due to the expensive nature of high frequency measurements in the EMC (Electromagnetic Compatability) field, more affordable methods of measurement instrumentation and environments are investigated. Different calibration methods for an Automatic Network Analyser (ANA) are evaluated against each other to determine the most cost-effective method of calibration. The mathematics for all the calibration methods are used in MATLAB programs which perform the error-calculation and correction which is usually done by the ANA software. These programs can be used to develop a simplified homebuilt ANA at reduced cost. The MATLAB program calibrations are compared to actual ANA calibrations to determine accuracy. Different measurement environments are considered as well to decide on a best compromise between cost and accuracy. To achieve this a reverberation chamber was built in which measurements were done and compared to measurements done on an Open Area Test Site. The Device Under Test was a standard radiator constructed specifically for such measurements. The development of both the radiator and the reverberation chamber are discussed and all the measurement results are considered in this thesis.

La cohabitaion, dans une même enceinte, des systèmes électroniques de puissance et decommande est un risque majeur pour le bon fonctionnement des systèmes électroniquesembarqués (Automobile, Aéronautique et Spatial). La maitrise de la CEM de ces systèmes estun défit surtout avec la difficulté de rendre compte des phénomènes EM.Ce mémoire décrit la modélisation des émissions conduites et des émissions EM rayonnéespar le câblage des systèmes électroniques embarqués. On explique d’abord le choix del’utilisation de la méthode de modélisation PEEC puis on décrit sa formulationmathématique et on présente les différents phénomènes EM qu’elle prend en compte dansle contexte de câblage.Dans le deuxième chapitre, un calcul tridimensionnel des émissions EM rayonnées a étéproposé. Il prend en compte de la géometrie des cellules de discrétisation et permet unemeilleure considération de la montée en fréquence. Il permet ainsi de se rapprocher au plusprès de la structure. Une validation de ce calcul a été effectuée en comparant les résultatsde simulation à ceux obtenus par d’autres calculs analytiques, par modélisation « élémentsfinis » et aussi par des mesures en champ proche.Le troisième chapitre est consacré aux applications aux systèmes électroniques embarqués.Dans une première partie, une étude d’un système de câblage, qui reflète les différentsphénomènes rencontrés en automobile, a été faite. Ensuite, un câblage est associé à unconvertisseur DC/DC. Ce convertisseur est utilisé comme un générateur de perturbations EMen Hautes fréquences. Dans cette partie du travail, on présente une modélisation de cesperturbations qui se propagent vers le câblage et qui se transforment en émissions EMrayonnées. / The calculation of radiated electromagnetic (EM) fields from wiring systems such as cables in automotive/aeronautic applications is an important issue for the prediction and the prevention of EM Interference (EMI) and EM Compatibility (EMC) problems. Many numericalmethods of electromagnetic modeling are available and can be used for EM analysis. Amongthese methods, the Partial Element Equivalent Circuit method (PEEC) is particularly wellsuited. Usually the PEEC approach is an efficient way to deal with circuit simulation ofdistributed structures. In automotive/aeronautic applications, the electronic systemsoperate at increasingly higher frequencies. So, the radiation of cables cannot be neglected. A3D model based on the PEEC method was proposed in order to take into account the size ofautomotive wiring systems. It includes resistive, inductive and capacitive effects. This 3Dapproach was shown to accurately predict the conducted disturbances by cables above largeground planes.In this work a new 3D calculation approach based on Maclaurin expansion is developed toevaluate the radiated fields with the PEEC method. The originality of this work is consideringboth radiated and conducted disturbances in the framework of a PEEC method for large sizestrcutures. In a first step the current carried by the conductors are determined from thecircuit model deduced with the 3D PEEC method. Then in a second step the field radiated bythe wiring systems is evaluated using an analytical calculation deduced from the distributionof currents.The third part of this work is to identify the disturbances generated

A magnetohidrodinâmica, ou simplesmente MHD, é um campo da ciência que estuda os movimentos de fluidos condutores submetidos a forças eletromagnéticas e une conceitos da fluidodinâmica e eletromagnetismo. Nos últimos anos, a MHD vem sendo aplicada em diversas áreas tecnológicas, desde a propulsão eletromagnética até dispositivos biológicos. Neste trabalho, são mostradas a construção e a operação de um dispositivo MHD, um canal retangular preenchido com um fluido eletrolítico conhecido como macrobomba, isento de partes mecânicas móveis. Os imãs geram um campo magnético externo e os eletrodos criam um campo elétrico, perpendicular ao escoamento, que move o fluido. O modelo MHD é calculado a partir das equações de Navier Stokes acopladas às equações de Maxwell para um fluido incompressível newtoniano. As forças eletromagnéticas que surgem resultam do produto vetorial da densidade de corrente e da densidade de fluxo magnético - essa é a força de Lorentz. Os resultados são apresentados em simulações 3D numéricas, assim como em dados experimentais. O objetivo é relacionar o campo magnético com o elétrico e com a quantidade de movimento produzida, e calcular a densidade de corrente e o perfil de pressão e de velocidade. Um perfil U e M de pressões e velocidades é esperado no experimento. Dados experimentais e computacionais são comparados para validação e posterior uso para futuros trabalhos. / Magnetohydrodynamics or simply (MHD) is a field of science that studies the movement of conductive fluids subjected to electromagnetic forces. Such a phenomenon brings together concepts of fluid dynamics and electromagnetism. Over the years, MHD has been encountered in a wide area of technological applications electromagnetic propulsion to biological devices. The present work didactically shows the construction (materials and equipment) and operation of an MHD device; a rectangular closed circuit filled with an electrolyte fluid, known as macro pumps, where a permanent magnet generates a magnetic field and electrodes generate the electric field, perpendicular to the flow, moving the fluid. The MHD model has been derived from the Navier-Stokes equation and coupled with the Maxwell equations for Newtonian incompressible fluid. Electric and magnetic components engaged in the test chamber assist in creating the propulsion of the electrolyte fluid. The electromagnetic forces that arise are due to the cross product between the vector density of current and the vector density of magnetic field applied. This is the Lorentz force. Results are present of 3D numerical MHD simulation for Newtonian fluid as well as experimental data. The goal is to relate the magnetic field with the electric field and the amounts of movement produced, and calculate de current density and fluid´s pressure and velocity. An u-shaped and m-shaped velocity and pressure profiles are expected in the experiment. Computational and experimental data are compared for validation and future analysis.

Dans le domaine de la sécurisation des circuits intégrés, tel que les cartes à puce, les concepteurs de circuits sont contraints à innover, inlassablement, afin de trouver de nouvelles parades aux nouvelles attaques, notamment par canaux cachés. En effet, ces attaques, comme l'analyse des émissions électromagnétiques, permettent d'extraire des informations, contenues à l'intérieur des circuits, sensées être secrètes. Partant de ce constat, dans cette thèse, nous nous sommes focalisés sur l'étude et l'analyse électromagnétique et ce afin de quantifier les possibilités de ces attaques. Ce manuscrit est organisé de la manière qui suit. Dans un premier temps, une plateforme de mesures des émissions électromagnétiques temporelles, que nous avons développées, est présentée, ainsi que des résultats qui ont été obtenus, avec celle-ci, sur différents circuits. A partir de ces résultats, une synthèse des possibilités, relatives à la menace sécuritaire que constituent les analyses électromagnétiques est proposée ainsi que, des propositions de solutions, visant à réduire le rayonnement électromagnétique des circuits intégrés. Dans un second temps, nous nous sommes intéressés aux méthodes de simulation de ces émissions électromagnétiques. Un état de l'art, des outils de simulation existants aujourd'hui, nous a permis de mettre en évidence qu'aucun d'eux ne permet d'avoir une résolution suffisamment fine en termes d'émissions électromagnétiques. Afin de combler ce manque, un flot de simulation a été développé. Pour valider ce flot, une comparaison entre les résultats de mesure et les résultats de simulation a été effectuée. / In the area of secure integrated circuits, such as smart cards, circuit designers are always looking to innovate to find new countermeasures against attacks by the various side channels that exist today. Indeed, side channels attacks such as the analysis of electromagnetic emissions permit to extract secret information contained in circuits. Based on this observation, in this thesis, we focused on the study of electromagnetic analysis to observe the analysis possibilities. This manuscript is organized as follows. Initially, we presented a measurement system for electromagnetic emissions in time domain, and the results obtained on different circuits. From these results, a summary of opportunities, relating to the security threat, posed by electromagnetic analysis, is proposed as well as solutions proposals to reduce electromagnetic radiations of integrated circuits. In a second step, we are interested in the simulation of electromagnetic emissions. A state of the art of simulation tools which exist today, has allowed us to demonstrate that none of them allowed to have a fine enough resolution in terms of electromagnetic emissions. To fill this gap, a simulation tool has been developed and to validate this flow, a comparison between measurement results and simulation results was performed.

This study is performed as a partial aid to a larger study that aims to determine if electromagnetic fields produced by underwater power cables have any effect on marine species. In this study, a new numerical method for calculating magnetic fields around subsea power cables is presented and tested. The numerical method is derived from electromagnetic theory, and the program, Matlab, is implemented in order to run the simulations. The Matlab code is validated by performing a series of tests in which the theoretical code is compared with other previously validated magnetic field solvers. Three main tests are carried out; two of these tests are physical and involve the use of a magnetometer, and the third is numerical and compares the code with another numerical model known as Ansys. The data produced by the Matlab code remains consistent with the measured values from both the magnetometer and the Ansys program; thus, the code is considered valid. The validated Matlab code can then be implemented into other parts of the study in order to plot the magnetic field around a specific power cable. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

A magnetohidrodinâmica, ou simplesmente MHD, é um campo da ciência que estuda os movimentos de fluidos condutores submetidos a forças eletromagnéticas e une conceitos da fluidodinâmica e eletromagnetismo. Nos últimos anos, a MHD vem sendo aplicada em diversas áreas tecnológicas, desde a propulsão eletromagnética até dispositivos biológicos. Neste trabalho, são mostradas a construção e a operação de um dispositivo MHD, um canal retangular preenchido com um fluido eletrolítico conhecido como macrobomba, isento de partes mecânicas móveis. Os imãs geram um campo magnético externo e os eletrodos criam um campo elétrico, perpendicular ao escoamento, que move o fluido. O modelo MHD é calculado a partir das equações de Navier Stokes acopladas às equações de Maxwell para um fluido incompressível newtoniano. As forças eletromagnéticas que surgem resultam do produto vetorial da densidade de corrente e da densidade de fluxo magnético - essa é a força de Lorentz. Os resultados são apresentados em simulações 3D numéricas, assim como em dados experimentais. O objetivo é relacionar o campo magnético com o elétrico e com a quantidade de movimento produzida, e calcular a densidade de corrente e o perfil de pressão e de velocidade. Um perfil U e M de pressões e velocidades é esperado no experimento. Dados experimentais e computacionais são comparados para validação e posterior uso para futuros trabalhos. / Magnetohydrodynamics or simply (MHD) is a field of science that studies the movement of conductive fluids subjected to electromagnetic forces. Such a phenomenon brings together concepts of fluid dynamics and electromagnetism. Over the years, MHD has been encountered in a wide area of technological applications electromagnetic propulsion to biological devices. The present work didactically shows the construction (materials and equipment) and operation of an MHD device; a rectangular closed circuit filled with an electrolyte fluid, known as macro pumps, where a permanent magnet generates a magnetic field and electrodes generate the electric field, perpendicular to the flow, moving the fluid. The MHD model has been derived from the Navier-Stokes equation and coupled with the Maxwell equations for Newtonian incompressible fluid. Electric and magnetic components engaged in the test chamber assist in creating the propulsion of the electrolyte fluid. The electromagnetic forces that arise are due to the cross product between the vector density of current and the vector density of magnetic field applied. This is the Lorentz force. Results are present of 3D numerical MHD simulation for Newtonian fluid as well as experimental data. The goal is to relate the magnetic field with the electric field and the amounts of movement produced, and calculate de current density and fluid´s pressure and velocity. An u-shaped and m-shaped velocity and pressure profiles are expected in the experiment. Computational and experimental data are compared for validation and future analysis.

by Hung King Fai Kevin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 82-85 (2nd gp.)). / Abstracts in English and Chinese. / ACKNOWLEDGEMENT --- p.ii / ABSTRACT --- p.iii / 摘要 --- p.v / TABLE OF CONTENTS --- p.vi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- OBJECTIVES --- p.1 / Chapter 1.2 --- NEED FOR PATIENT-MONITORING SYSTEM --- p.1 / Chapter 1.2.1 --- Aging Population --- p.1 / Chapter 1.2.2 --- Increasing Population with Heart Diseases --- p.2 / Chapter 1.3 --- ECG BASICS --- p.3 / Chapter 1.4 --- EXISITING ECG-MONITORING TECHNOLOGIES --- p.4 / Chapter 1.5 --- CHALLENGES IN PATIENT-MONITORING --- p.5 / Chapter 1.6 --- DEVELOPMENT OF AN ECG-MONITORING SYSTEM --- p.6 / Chapter 1.6.1 --- Overall Structure --- p.6 / Chapter 1.6.2 --- Considerations --- p.7 / Chapter CHAPTER 2 --- EMI FILTERS IN ECG ACQUISITION CIRCUIT --- p.8 / Chapter 2.1 --- OVERVIEW OF NOISE SOURCES IN ECG ACQUISITION --- p.8 / Chapter 2.1.1 --- Other Biopotentials --- p.8 / Chapter 2.1.2 --- Motion Artifact --- p.8 / Chapter 2.1.3 --- Power-line Interference --- p.10 / Chapter 2.1.4 --- High-Frequency Electromagnetic Interference --- p.15 / Chapter 2.2 --- EMI FILTERS --- p.16 / Chapter 2.2.1 --- Introduction to EMI Filters --- p.16 / Chapter 2.2.2 --- Types of EMI Filter --- p.17 / Chapter 2.2.3 --- EMI Filters in ECG Monitoring --- p.21 / Chapter 2.3 --- MODELING OF INTERFERENCE IN ECG-MONITORING SYSTEM --- p.22 / Chapter 2.3.1 --- Model and Parameters --- p.22 / Chapter 2.3.2 --- Method --- p.24 / Chapter 2.3.2 --- Results --- p.27 / Chapter 2.3.3 --- Discussion --- p.30 / Chapter 2.4 --- BUILDING AN ECG ACQUISITION CIRCUIT WITH EMI FILTERS --- p.30 / Chapter 2.4.1 --- Purpose --- p.30 / Chapter 2.4.2 --- Experimental Setup and Method --- p.30 / Chapter 2.4.3 --- Results --- p.32 / Chapter 2.4.4 --- Discussion --- p.46 / Chapter CHAPTER 3 --- ADAPTIVE FILTER --- p.48 / Chapter 3.1 --- OBJECTIVE --- p.48 / Chapter 3.2 --- INTRODUCTION TO ADAPTIVE FILTER --- p.48 / Chapter 3.3 --- METHOD --- p.50 / Chapter 3.4 --- RESULTS --- p.52 / Chapter 3.5 --- DISCUSSION --- p.57 / Chapter CHAPTER 4 --- WAP-BASED TELEMEDICINE APPLICATIONS --- p.59 / Chapter 4.1 --- INTRODUCTION TO TELEMEDICINE --- p.59 / Chapter 4.2 --- INTRODUCTION TO WAP --- p.59 / Chapter 4.3 --- WAP APPLICATIONS --- p.60 / Chapter 4.4 --- SYSTEM IMPLEMENTATION --- p.63 / Chapter 4.4.1 --- Overall Structure --- p.63 / Chapter 4.4.2 --- Relational Database --- p.63 / Chapter 4.4.3 --- Program Flow --- p.64 / Chapter 4.4.4 --- ECG Browsing and Feature Extraction --- p.70 / Chapter 4.5 --- EMULATION --- p.72 / Chapter 4.6 --- EXPERIENCE WITH WAP PHONE --- p.74 / Chapter 4.7 --- DISCUSSION AND CONCLUSION --- p.75 / Chapter CHAPTER 5: --- CONCLUSION AND FUTURE WORK --- p.77 / Chapter 5.1 --- CONCLUSION --- p.77 / Chapter 5.2 --- FUTURE WORK --- p.77 / Chapter 5.3 --- MARKET ANALYSIS --- p.79 / BIBLIOGRAPHY --- p.80

This thesis investigates geo-electric fields in the United Kingdom with particular regard to Geomagnetically Induced Currents (GIC) in the Scottish Power electricity transmission network (SPTN). The joint spectral characteristics of Scottish Power GIC and Eskdalemuir magnetic observatory data are analysed, and GIC are shown to be coherent with magnetic field variations over the period range 2-1100s. A bi-variate transfer function model of the physical link between magnetic field variations and GIC demonstrates that long-period (>200s) induction makes a first order contribution to the observed GIC at one SPTN site, and dominates the response at another. Thin-sheet modelling at a period of 750s is used to explore the relative influence of three factors on the size and spatial distribution of the calculated electric field: (i) the contrast in conductance between the sea and the land; (ii) variations in conductance due to sea depth; (iii) lateral variations in conductance representative of those in the geographic area occupied by the SPTN. The modelling suggests that a `coast-only' model (i) will over-predict electric field magnitudes in the SPTN region by a factor of 2-5 in comparison with model (iii). Distortion analysis of Magnetotelluric (MT) data at a period of 750s acquired over numerous field campaigns reveal pervasive galvanic distortion of the electric field in the SPTN region. GIC transfer functions of one site are consistently interpreted as proxy MT responses, and it is shown that galvanic distortion of the electric field modifies significantly the GIC amplitude response. A prototype model of the SPTN developed by the British Geological Survey and the Finnish Meteorological Institute is used to calculate GIC. It is shown that neglect of lateral variations of conductivity may lead to false conclusions about the direction of the external electric field that maximises GIC. Time derivatives of the Eskdalemuir horizontal magnetic field are used as an index of GIC activity, and to select events which may have led to large GIC in the time period (1983-2000) prior to the monitoring of GIC by Scottish Power. Backwards-prediction using the GIC transfer functions and observatory magnetic data suggests that GIC at the Scottish Power monitoring sites have amplitudes less than approximately 30A.

Modern gridded ion thrusters for CubeSats operate by generating high power and canpose challenging problems with Electromagnetic Interference (EMI). In order to verifycompatibility with neighbouring equipment, strict standards such as the militarystandard MIL-STD-461G, are required to be followed to achieve ElectromagneticCompatibility (EMC). To avoid abrupt and cataclysmic delays in production time, incase the product fails to comply with the requirements, companies integrate in-housepre-compliance tests into their development phase. The objective is to implementin-house measurement methods on an electric propulsion model NPT30 developedby ThrustMe. This document explains the process and methods to perform conductedemission test on power lines and radiated emission tests in the magneticfield. A custom measurement system integrity verification was developed for theradiated emission test. The presented results provide the engineers at ThrustMe aninsight on the electromagnetic behaviour on the ion thruster NPT30 and whethermodifications need to be included in the next development iteration to mitigate forthe detected excessive emission levels. When EMC methods are implemented earlyon in the development process, there are more pre-emptive mitigation options withless costs in time and money. By performing in-house pre-compliance tests andtaking measures to prepare for the tests at a certified EMC test house, the companycan be more confident in their product at passing the EMC tests. Based on the twoperformed in-house tests, the engineers at ThrustMe began to include mitigationmethods in the following circuit design iterations.