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

Au fur et à mesure que le nombre de composants augmente, il existe une forte demande pour identifier les sources de rayonnement pour la prédiction de la compatibilité électromagnétique des circuits électroniques. Le balayage d’une sonde à proximité du circuit est une méthode générale d'identification des sources rayonnantes dans une PCB. La première partie de la thèse consiste à concevoir et à caractériser des sondes magnétiques à haute sensibilité et à haute résolution spatiale. Les sondes conventionnelles basées sur la ligne micro ruban et la configuration coplanaire sont étudiées. À mesure que la longueur de la ligne de transmission connectée à la sonde augmente, le bruit sur le signal de sortie augmente en raison de tensions de mode commun induites par le champ électrique. Afin de supprimer cette tension induite par le champ électrique, une sonde magnétique blindée est conçue et fabriquée à l'aide d'une technologie de circuit imprimé à faible coût (PCB). La performance de la sonde passive est validée dans la bande 1MHz - 1GHz. La sonde blindée est fabriquée sur un substrat FR4 d'une épaisseur de 0,8 mm et se compose de 3 couches avec le signal dans la couche intermédiaire et les couches supérieure et inférieure dédiées aux plans de masse. La taille d'ouverture de la boucle est de 800 μm x 800 μm, avec une résolution spatiale attendue de 400 μm. La haute sensibilité de la sonde est obtenue en intégrant un amplificateur à faible bruit à la sortie de la sonde, ce qui en fait une sonde active. La performance de la sonde blindée avec différentes longueurs de lignes de transmission est faite pour étudier. Une sonde à trois axes capable de mesurer les trois composantes du champ magnétique est également conçue et validée par un balayage en champs proches au-dessus d'une structure standard plan de masse.Dans la deuxième partie, la méthode de la matrice de la ligne de transmission inverse (Inv-TLM) est utilisée, pour reconstruire la distribution source à partir des champs proches (NFS) mesurés au-dessus d'un plan sur la carte PCB. Même si, la résolution de la reconstruction dépend de la longueur d'onde et des paramètres du maillage, la propagation inverse augmente la largeur de l'onde reconstruite. Comme cette méthode corresponde à un problème « mal posé» et entraîne des solutions multiples, nous avons développé une nouvelle méthode basée sur la corrélation croisée bidimensionnelle, qui représente les données de balayage en champ proche sous forme de de dipôles équivalents. Avec cette nouvelle méthode, nous avions pu identifier et de localiser les sources actuelles dans le PCB et est représenté avec des sources équivalentes. La méthode est validée pour les sources avec des orientations différentes. Les données simulées des champs proches utilisant le logiciel commercial CST sont utilisées pour valider les deux méthodes. Le champ lointain prédit à partir de ces sources équivalentes est comparé aux champs simulés. / As the number of components in a confined volume is increasing, there is a strong demand for identifying the sources of radiation in PCBs and the prediction of EMC of electronic circuits. Electromagnetic near field scanning is a general method of identifying the radiating sources in a PCB. The first part of the thesis consists of the design and characterization of printed circuit magnetic probes with high sensitivity and high spatial resolution. Conventional probes based on microstrip and coplanar configuration is studied. As the length of the transmission line connected to the probe increases, the probe output contains noise due to common mode voltages which is many induced by the electric field. In order to suppress the voltage induced due to the electric field, a shielded magnetic probe is designed and fabricated using low cost printed circuit board (PCB) technology. The performance of the passive probe is calibrated and validated from 1MHz – 1GHz. The shielded probe is fabricated on an FR4 substrate of thickness 0.8mm and consists of 3 layers with the signal in the middle layer and top and bottom layers dedicated to ground planes. The aperture size of the loop is 800µm x 800µm, with an expected spatial resolution of 400 µm. The high sensitivity of the probe is achieved by integrating a low noise amplifier at the output of the probe, hence making an active probe. The performance of the shielded probe with a different length of transmission lines is made to study. When the probe has to be operated above 100MHz, it is found that the transmission lines connected to the probe should be short (around 1.5cmm). For frequencies below 100MH, the length of the lines can be up to 12cm. A three-axis probe which is able to measure the three components of the magnetic field is also designed and validated by near field scanning above a standard wire over the ground structure.In The second part, the inverse transmission line matrix method (Inv-TLM) method is used reconstruct the source distribution from the near field scan (NFS) data above a single in plane on the PCB. Even though the resolution of reconstruction depends on the wavelength and the mesh parameter, the inverse propagation increases the width of the reconstructed wave. As this method is found to be ill posed and results in multiple solutions, we have developed a new method based on the two-dimensional cross-correlation, which represents the near field scan data in terms of the equivalent electric currents of the dipole. With the new method, we are able to identify and locate the current sources in the PCB and are represented by an equivalent source. The method is validated for the current sources with different orientations. The simulated near field data using CST microwave studio is used to validate both the methods. The radiated far field from these equivalent sources is compared with the simulated fields.

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-09Bitstream added on 2014-06-13T19:08:07Z : No. of bitstreams: 1 yamanaka_fnr_me_ilha.pdf: 596127 bytes, checksum: 6456b9483b4e3ac56e9f1fded745845f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / 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. / 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.

Диплом посвящен описанию методики моделирования системы передачи данных на симметричных линии передач. Приведена методика построения моделей систем в программной среде NI AWR Design Environment. Производится разбор этапов построения модели. / Diploma is dedicated to the describe method of modeling of transmission system build upon symmetric transmission lines. Method of modeling in NI AWR Design Environment been presented. An extensive explanation of modeling process is given.

Master of Science / Department of Electrical and Computer Engineering / Noel Schulz / Transmission networks are an important part of an electric power system. They help transfer power from the point of generation (power plants) to the substation. In order to minimize losses during power transfer, the lines are operated at high voltages. The high voltage lines not only have a high power transmission capacity, but they are also prone to faults of larger magnitudes. Thus the occurrence of such faults results in a need for the faults to be cleared quickly in order to limit damage caused to the system. Hence, relays are installed at the Buses to provide protection to the lines. Transmission lines in a power system are most commonly protected by distance relays that use directional comparison schemes. However, due to the simplicity of line differential schemes, there has been an increase in the use of differential relays for complex networks. Moreover, since the relays require only current as the operating parameter, their settings can be determined easily. This report discusses the design of a line current differential protection scheme for a transmission line using SEL 311L relays. The relay settings have been determined and then tested for seven fault scenarios, three internal fault points and four external fault points. To set and test the relays, AcSELerator Quickset, SEL 5030 and PowerWorld programs have been used. Real life power system is simulated with the help of SEL AMS (Adaptive Multichannel Source) that acts as the source to provide the required data to the relays. The relays trip and open the breaker contacts for an internal fault. During an external fault, the relays do not trip and the breaker contacts remain closed. The response of the relays in case of communication failures has been discussed.

In pneumatic pressure control applications the influence of tubes that connect the valve with the control volume ist mainly neglected. This can lead to stability and robustness issues and limit either control performance or tube length. Modeling and considering tube behavior in controller design procedure allows longer tubes while maintaining the required performance and robustness properties without need for manual tuning. The author\'s previously published Simplified Fluid Transmission Line Model and the proposed model-based controller design enable the specification of a desired pressure trajectory in the control volume while the pressure sensor is mounted directly at the valve. Thus wiring effort is reduced as well as cost and the chance of cable break or sensor disturbance. In order to validate the simulated results the proposed control scheme is implemented on a real-time system and compared to a state-of-the-art pressure regulating valve

This paper presents the mathematical modeling and the design of an optimal pressure tracking controller for an often used setup in pneumatic applications. Two pneumatic chambers are connected with a pneumatic tube. The pressure in the second chamber is to be controlled using two switching valves connected to the first chamber and based on the pressure measurement in the first chamber. The optimal control problem is formulated and solved using the MPC framework. The designed controller shows good tracking quality, while fulfilling hard constraints, like maintaining the pressure below a given upper bound.

This thesis introduces a comprehensive methodology to improve electromagnetic transient (EMT) modelling of power cables systems. Several improved modelling and validation techniques are proposed at the parameter estimation, time domain simulation and validation stages of the EMT modelling of transmission lines. A novel approach is developed to model sector-shaped cables in electromagnetic transient type programs. First, the applicability of elemental sub-conductor technique is extended to accurately calculate the frequency dependent impedances of sector-shaped cables. The derived admittance and propagation characteristics of the sector-shaped cable are fitted with rational functions using the method of vector fitting in an EMT-type program. The time domain simulations are validated with the numerical inverse Laplace transform method. A novel frequency domain approach is presented to model cascaded transmission systems. The procedure is based on obtaining four composite propagation functions representing the cascaded system. The performance of the technique does not diminish with increased number of cascaded segments and it preserves the intrinsic details of each line segment. This method is capable of modelling cascaded overhead lines or cables with different characteristic admittances and line lengths. This method can be used to validate EMT models of cascaded transmission systems. An improved generalized transmission line model is introduced which is capable of accommodating time steps greater than the travel time of the line. The time step of the conventional EMT models of transmission lines is constrained by the smallest travel time of the line. When the high frequency transients at the line terminations are not of interest, inaccurate nominal π equivalents are used with large time steps to reduce the computational burden. The proposed model not only is more accurate than the π equivalents, but also degenerates to the conventional frequency dependent EMT model when used with time steps smaller than the travel time. Therefore, the proposed model is highly convenient as it can be used for all types of EMT simulations without resorting to nominal π equivalents when the large simulation time steps must be used to reduce computational burden. / February 2017

In the past two decades carbon nanotubes and graphene have attracted a lot of research attention due to their exceptional electronic properties. The research focus on improving the synthesising techniques will eventually lead to their applications in terahertz wave, millimetre wave and microwave frequencies. In this thesis, a modelling technique based on the transmission line theory is proposed to calculate the 2-port S-parameters of vertically aligned CNT arrays with finite sizes and arbitrary cross sections. The process takes into account all the coupling in the array and gives the analytical solution of S-parameters. The simulation results from the proposed technique are compared with results obtained by effective single conductor model and shows a good matching for small arrays and an increasing difference with the increase of array sizes. From the S-parameters, the fundamental properties of CNT arrays such as input impedance and absorption are obtained and compared with measurement results in microwave frequencies. The dependence of these properties on ambient temperature and host medium are also presented to explore the tunability of CNT arrays. From the Fabry-Perot the wave propagating velocity is also calculated for arrays with different sizes and fitted with a power function. The S-parameters allows the extraction of the complex permittivity, permeability and conductivity of the CNT array. The extracted permittivity and absorption are compared with measurement results. The graphene nanoribbons are simulated in the same manner. The graphene sheet on top of a microstrip gap is simulated using transmission line model at microwave frequencies to show the impact of parasitics and contact resistances. Finally, a graphene based microwave absorber is proposed and modelled under both electric and magnetic bias. The absorber shows good broadband absorption rate and a potential for turning transparent and opaque to microwaves under both electric and magnetic bias.

Low-loss waveguides with minimal dispersion are desired throughout the electromagnetic spectrum. These properties are difficult to achieve in the Terahertz (THz) region due to material and geometric constraints. This thesis focuses on the design, fabrication, and testing of waveguide-based devices using two promising technologies: the free-space metallic-slit waveguide (MSWG) and the coplanar strip (CPS) waveguide on a thin (1 um) commercial silicon nitride membrane. The work presented here differs from standard THz waveguide research which commonly uses the field radiated by a photoconductive antenna (THz optics) for excitation and detection. To improve upon system integration, a focus is placed on planar waveguide devices without refractive THz elements. Three main waveguide devices are investigated. First, an edge-coupled MSWG-based linear tapered slot antenna (LTSA) was used for THz-Time Domain Spectroscopy (TDS). This device functions as an alternative to a standard photoconductive switch coupled to a silicon lens and maintains comparable performance. Next an edge-coupled tapered MSWG was investigated. The MSWG conductor separation was increased to a low-loss configuration where the field propagated for 24 mm, after which the conductors were tapered to focus the field onto the receiving active region where a THz-bandwidth pulse was detected. Finally a CPS waveguide was fabricated on a thin silicon nitride membrane where a THz-bandwidth pulse was detected after propagating for 10 mm. The active regions for this device were fabricated using a unique method. This method results in the creation of thousands of small (40 um x 20 um) active regions (from a 4 mm x 4 mm host substrate) which can be placed anywhere for THz excitation and detection. The small active regions in conjunction with the CPS waveguide on the silicon nitride membrane provide an excellent platform for THz system testing. A single membrane can host many THz circuits which can be made ``active" by the placement of a few thin-film photoconductive devices. Main potential future applications include waveguide-based spectroscopy and coherent THz-bandwidth circuit analysis. / Graduate