CD and DVD became the major portable and backup data storage devices because their reliability and economical cost when mass produced. As the computer technology grew, higher data storage density on CD/DVD disc was demanded. Using a shorter wavelength light source was the common technique to achieve this goal from both research and industry. However, the limit of wavelength had almost reached for applying it to optical storage. The nano-scale metallic wire polariser that was designed in this thesis provided a possible solution. This thesis introduces the method of using the nano-scale metallic wires to form a grating polariser as the data pit on CD/DVD disc. The polariser is a type of scattering polariser and could transmit one linear polarisation of the light and reject its orthogonal counter part. The designed pattern was tested by using XFDTD, an electromagnetic simulation program based on the finite difference time domain method. As the wave source was a red laser with a wavelength of 650nm, the simulation cell size was set to be 10nm. The dispersive materials were simulated by the Debye model. The electric field results were measured on X, Y, and Z components. The results were analysed by a pre-written Matlab program to find the transmission and crosstalk coefficients. The single polariser simulations showed that there are great potentials in this design. However, inter-cell crosstalk became the major problem in the polariser array simulations. The groove pattern and titanium material were used to optimise the polarisation effect. The simulation showed that a standard-sized disc with a titanium polariser array could have 5.5GB storage capacity and a 15 to 20dB inter-cell extinction ratio for an optical pickup with a red laser (650nm) and a numerical aperture (NA) of 0.6. Although the improvement is only marginal over existing optical data storage technology, there are many further researches possible to carry on such as the fabrication of the polariser arrays.

A new method for the simulation of radio frequency (RF) coils has been developed. This method utilizes the FEM simulation package Ansoft HFSS as a base for the modeling of RF coils with complex biological loading effects. The abilities of this software have been augmented with custom MATLAB code to enable the fast prediction of lumped element values needed to properly tune and match the coil structure as well as to perform the necessary post processing of simulation data in order to quickly generate and evaluate field data of the resonating coil and compare design variations. This method was evaluated for accuracy and implemented in the re-design of an existing four channel breast coil array for clinical imaging of the female breasts. Based on the simulation results, a commercially viable printed circuit board (PCB) implementation was developed and tested in a clinical 1.5 T MR scanner. The new design allows for wide open bilateral access to the breast regions in order to accommodate various interventional procedures. The layout has also increased axillary B1 field coverage with minor penalty to the signal-to-noise ratio of the coil array, enabling high-resolution imaging over a wide field-of-view.

A new approach is presented that relies upon 3D electromagnetic simulation results to characterize the complex permittivity of homogeneous dielectric materials. By modeling the test fixture and obtaining a set of simulated S-parameters through an iterative solution process, the dielectric constant and loss tangent can be found. With further development, the 3D simulation results may be used to replace the need for complex theoretical analysis of the measurement geometry. The method is applied to an X-band rectangular waveguide setup, for which the theoretical S-parameters can be readily calculated. A Teflon sample, for which the dielectric properties are well-known, is used for all measurements and calculations. After presenting a detailed derivation to obtain the theoretical S-parameters, the Teflon sample is measured and compared to the theoretical results, from which the comparison shows great promise. An inverse solution algorithm is used to solve for the material properties from the experimental S-parameters. Low-frequency measurement of the Teflon sheet was performed by using a dielectric capacitor test fixture. The results show the effect of an air gap between the electrode and sample, producing serious errors. / Master of Science

No description available.

Nesta tese desenvolveram-se projetos e modelos de indutores planares para circuitos integrados de radiofrequência nas arquiteturas espiral e cross para as tecnologias CMOS AMS 0,35 ?m e IBM 0,13 ?m, visando representar o desempenho destes na faixa de frequências de corrente contínua até 90% da frequência de ressonância. A modelagem empregada utiliza um circuito elétrico equivalente com nove elementos para representar indutores, para o qual é apresentado um processo para extração dos valores dos seus componentes a partir de dados simulados ou medidos. Foi apresentada uma versão estendida da arquitetura cross original, mais flexível e tratável por algoritmos, com uma indutância 25% maior que a arquitetura espiral de mesma área. Utilizou-se planejamento de experimentos para elaborar conjuntos de amostras de indutores com dimensões geométricas variadas nas arquiteturas e tecnologias estudadas, para os quais desenvolveu-se um conjunto de algoritmos específicos para o projeto dos indutores a partir de suas dimensões. A simulação eletromagnética do layout de cada amostra gerou os resultados empregados no desenvolvimento do processo de extração dos valores dos componentes do circuito equivalente, os quais foram relacionados às dimensões geométricas dos indutores através de equações de projeto elaboradas por meio de análise de regressão multivariada e modelos lineares generalizados. Tanto o processo de extração dos valores dos componentes, como as equações de projeto foram validados estatisticamente pela comparação dos resultados das simulações dos respectivos circuitos equivalentes com os resultados das simulações eletromagnéticas dos layouts dos indutores em cada arquitetura e tecnologia, demonstrando a correspondência entre estes. Discrepâncias observadas em alta frequência entre os resultados de simulação eletromagnética dos indutores e seus respectivos circuitos equivalentes são associados a limitações do modelo de circuito usado, que não considera os fenômenos de correntes de Foucault (correntes de turbilhonamento) e efeito pelicular. O processo de modelagem desenvolvido, devido a sua generalidade, pode ser aplicado ao desenvolvimento de outros modelos de circuito elétrico para indutores, ou mesmo para modelagem de outros componentes passivos para circuitos integrados, como capacitores, resistores e transformadores. / In this thesis were developed designs and models for planar inductors for radiofrequency integrated circuits in the spiral and cross architectures for AMS 0.35 ?m and IBM 0.13 ?m CMOS technologies, aiming to represent the inductors performance in the frequency range of direct current up to 90% of resonant frequency. The employed modeling used an equivalent circuit for inductors with nine elements, for which a process for extracting the values of its components from simulated or measured data is presented. An extended version of the original cross architecture was presented, more flexible and treatable by algorithms, with an inductance 25% larger than the spiral architecture of the same area. Design of experiments was used to elaborate sets of inductor samples with different geometric dimensions in the studied architectures and technologies. Algorithms were developed to design the layout of each inductor considering its architecture and specific dimensions. The layout electromagnetic simulation of each sample generated the results used in the process developed for extracting the values of the components of the equivalent circuit model, which were related to the geometric dimensions of the inductors through design equations elaborated by multivariate regression analysis and generalized linear models. Both the component extraction process and the design equations were statistically validated by comparing the simulation results of the respective equivalent circuit models with the results of the electromagnetic simulations of the inductor layouts in each architecture and technology, demonstrating matching between them. Observed discrepancies at high frequency between the electromagnetic simulation results for the inductors and their respective equivalent circuits are associated with limitations of the circuit model used, which does not consider eddy currents and skin effect phenomena. The modeling process developed, due to its generality, can be applied to the development of other electric circuit models for inductors, or even to model other passive components for integrated circuits, such as capacitors, resistors and transformers.

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.

The global population is constantly rising and with the consequent increase in demand for clean water, the planet is facing a looming freshwater shortage. At the current rate, cities around the globe could lose as much as two thirds of their freshwater supply by 2050. To tackle this, there has been a huge surge on the investigation of novel wastewater treatment technologies. Advanced oxidation processes (AOPs) have shown great promise in this regard. Recently using microwaves with AOPs has been proven to exhibit improved reaction rates and thus there is a push towards developing processes involving microwaves and AOPs to achieve high water treatment efficiencies. However no methodical studies have been conducted to the best of our knowledge, to take the lab scale improvements successfully on to the pilot scale wastewater treatment system. To design such a system by coupling microwaves with Fenton process is the objective of this microwave assisted catalytic treatment of wastewater (MICROCAT) research project. Multiphysics simulation was used for cavity design optimisation and common pesticides found in agricultural wastewater were used as candidate impurities. A heterogeneous Fenton catalyst was prepared by a multi-stage thermal and chemical treatment of polyacrylonitrile (PAN) mesh on polypropylene support structure in collaboration with De Montfort University (DMU). The PAN meshes, after each stage of the treatment process, have been characterised using the field emission gun scanning electron microscope (FEGSEM) and electron dispersive X-ray spectroscopy (EDX) for microstructure and composition. The catalyst was used to study the decomposition of a model compound (e.g., carbetamide) using microwave radiation as well as conventional heating. Two kinds of trials were carried out constant power and constant temperature to observe the effect of variation of process parameters on the reaction rates. It was seen that the use of microwave heating enhanced the rate of decomposition compared to conventional heating in both scenarios. Attempts were also made to modify the composition of the catalyst and the support structure using polyvinylidene fluoride (PVDF) and carbon based additives (graphite and carbon black) to improve the microwave absorption characteristics. The combination of additive and PAN/PVDF mixtures has the potential to help in designing a suitable fabric support for catalyst that could be more receptive to microwaves, thereby helping to improve the energy efficiency of the process. Thorough investigation of dielectric properties and microwave absorption characteristics of the catalyst and support materials were performed independently. The heating rates of the meshes were monitored using an infrared thermal imaging camera. The absorption efficiencies of materials commonly used to build water treatment reactors such as polypropylene (PP), Fibreglass reinforced plastic (FRP), polyvinyl chloride (PVC), glass, PTFE, and fused quartz were assessed by subjecting them to constant microwave power experiments to ascertain their utility for making the reactor parts To take the successful lab scale results (100 ml) to scalable levels (80000 ml) for field trails, a new microwave reactor system was designed and tested. The cavity design was aided by multiphysics simulation of the electromagnetic field and temperature distribution inside the cavity. The model was created using COMSOL and provided valuable insight in making several design choices and improvements. The material data used in the model was determined both from our characterisation results and from corroborative literature data. The cavity itself was fully constructed using aluminium and the internal components were made using polypropylene and PTFE within the project timeline. The cavity was commissioned and initial testing at end user sites involved experiments measuring the rate of decomposition of carbetamide and other pesticides the results again emphasising that microwave treatment improves the reaction rates both from lab scale and in pilot scale water treatment situations in comparison to conventional treatment systems. This augers well for the generic applicability of the microwave assisted catalytic reactor system and its potential for the efficient treatment of contaminated water from hard to treat agricultural. Industrial, medical and defence waste/pollutants in future. An added advantage is that the developed microwave treatment system is mobile (on an ISO-container) and hence can reach the remote, contaminated site and treat it then and there rather than transporting the contaminated fluid to the treatment plant in a faraway location.

Coaxial-to-microstrip launcher and microstrip patch array antenna are designed to work at center frequency of 36.85 GHz with a bandwidth higher than 300 MHz. The antenna array design also includes the feeding network distributing the power to each antenna element. The design parameters are defined on this report and optimized by using an Electromagnetic Simulation software program. In order to verify the theoretical results, microstrip patch array antenna is produced as a prototype. Measurements of antenna parameters, electromagnetic field and circuit properties are interpreted to show compliance with theoretical results. The values of deviation between theoretical and experimental results are discussed as a conclusion.

Fast methods for the electromagnetic simulation of integrated circuit (IC) package modules through model order reduction are demonstrated. The 3D integration of multiple functional IC chip/package modules on a single platform gives rise to geometrically complex structures with strong electromagnetic phenomena. This motivates our work on a fast full-wave solution for the analysis of such modules, thus contributing to the reduction in design cycle time without loss of accuracy. Traditionally, fast design approaches consider only approximate electromagnetic effects, giving rise to lumped-circuit models, and therefore may fail to accurately capture the signal integrity, power integrity, and electromagnetic interference effects. As part of this research, a second order frequency domain full-wave susceptance element equivalent circuit (SEEC) model will be extracted from a given structural layout. The model so obtained is suitably reduced using model order reduction techniques. As part of this effort, algorithms are developed to produce stable and passive reduced models of the original system, enabling fast frequency sweep analysis. Two distinct projection-based second order model reduction approaches will be considered: 1) matching moments, and 2) matching Laguerre coefficients, of the original system's transfer function. Further, the selection of multiple frequency shifts in these schemes to produce a globally representative model is also studied. Use of a second level preconditioned Krylov subspace process allows for a memory-efficient way to address large size problems.

The lunar Cherenkov technique is a promising method to resolve the mystery of the origin of the highest energy particles in nature, the ultra-high energy (UHE) cosmic rays. By pointing Earth-based radio-telescopes at the Moon to look for the characteristic nanosecond pulses of radio-waves produced when a UHE particle interacts in the Moon’s outer layers, either the cosmic rays (CR) themselves, or their elusive counterparts, the UHE neutrinos, may be detected. The LUNASKA collaboration aims to develop both the theory and practice of the lunar Cherenkov technique in order to utilise the full sensitivity of the next generation of giant radio telescope arrays in searching for these extreme particles. My PhD project, undertaken as part of the collaboration, explores three key aspects of the technique. In the first three chapters, I describe a Monte Carlo simulation I wrote to model the full range of lunar Cherenkov experiments. Using the code, I proceed to calculate the aperture to, and resulting limits on, a UHE neutrino flux from the Parkes lunar Cherenkov experiment, and to highlight a pre-existing discrepancy between existing simulation programs. An expanded version of the simulation is then used to determine the sensitivity of past and future lunar Cherenkov experiments to UHE neutrinos, and also the expected event rates for a range of models of UHE CR production. Limits on the aperture of the Square Kilometre Array (SKA) to UHE CR are also calculated. The directional dependence of both the instantaneous sensitivity and time-integrated exposure of the aforementioned experiments is also calculated. Combined, these results point the way towards an optimal way utilisation of a giant radio-array such as the SKA in detecting UHE particles. The next section describes my work towards developing accurate parameterisations of the coherent Cherenkov radiation produced by UHE showers as expected in the lunar regolith. I describe a ‘thinning’ algorithm which was implemented into a pre-existing electromagnetic shower code, and the extensive measures taken to check its veracity. Using the code, a new parameterisation for radiation from electromagnetic showers is developed, accurate for the first time up to UHE energies. The existence of secondary peaks in the radiation spectrum is predicted, and their significance for detection experiments discussed. Finally, I present the data analysis from three runs of LUNASKA’s on-going observation program at the Australia Telescope Compact Array (ATCA). The unusual nature of the experiment required both new methods and hardware to be developed, and I focus on the timing and sensitivity calibrations. The loss of sensitivity from finite-sampling of the electric field is modelled for the first time. Timing and dispersive constraints are used to determine that no pulses of lunar origin were detected, and I use my simulation software to calculate limits on an UHE neutrino flux from the experiment. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1371947 / Thesis (Ph.D.) - University of Adelaide, School of Chemistry and Physics, 2009.