O presente trabalho tem por objetivo avaliar o comportamento dos campos eletromagnéticos no interior de câmaras reverberantes de modos misturados através do método numérico TLM (Transmission Line Matrix). Inicialmente, apresenta-se uma descrição dos diversos tipos de câmaras aplicáveis na avaliação de desempenho de compatibilidade eletromagnética de equipamentos e sistemas elétricos, destacando-se suas principais características físicas e geométricas, com ênfase nas câmaras reverberantes. Os aspectos teóricos relacionados à descrição do método TLM são detalhados e sua aplicação na avaliação do ambiente eletromagnético das câmaras é então abordada. Diversos resultados são apresentados, considerando-se configurações pré-definidas de câmaras reverberantes, ressaltando-se a definição e cálculo de índices de mérito, bem como os principais aspectos relacionados à representação e definição de critérios adotados nas simulações destas. / The aim of this report is the evaluation of the behavior of electromagnetic fields inside reverberation chambers by means of Transmission Line Modeling (TLM). Initially, it is presented a description of several kinds of chambers applicable for electromagnetic compatibility tests followed by a more detailed description regarding reverberation chambers. Theoretical aspects of TLM method and its application for electromagnetic fields solution are covered. Some results are presented, considering pre-defined reverberation chambers configurations, highlighting some merit indicators and the main aspects adopted on its simulation.

O presente trabalho tem por objetivo avaliar o comportamento dos campos eletromagnéticos no interior de câmaras reverberantes de modos misturados através do método numérico TLM (Transmission Line Matrix). Inicialmente, apresenta-se uma descrição dos diversos tipos de câmaras aplicáveis na avaliação de desempenho de compatibilidade eletromagnética de equipamentos e sistemas elétricos, destacando-se suas principais características físicas e geométricas, com ênfase nas câmaras reverberantes. Os aspectos teóricos relacionados à descrição do método TLM são detalhados e sua aplicação na avaliação do ambiente eletromagnético das câmaras é então abordada. Diversos resultados são apresentados, considerando-se configurações pré-definidas de câmaras reverberantes, ressaltando-se a definição e cálculo de índices de mérito, bem como os principais aspectos relacionados à representação e definição de critérios adotados nas simulações destas. / The aim of this report is the evaluation of the behavior of electromagnetic fields inside reverberation chambers by means of Transmission Line Modeling (TLM). Initially, it is presented a description of several kinds of chambers applicable for electromagnetic compatibility tests followed by a more detailed description regarding reverberation chambers. Theoretical aspects of TLM method and its application for electromagnetic fields solution are covered. Some results are presented, considering pre-defined reverberation chambers configurations, highlighting some merit indicators and the main aspects adopted on its simulation.

The purpose of this thesis is to present solutions to overcome several key difficulties that limit the application of numerical modelling in communication cable design and analysis. In particular, specific limiting factors are that simulations are time consuming, and the process of comparison requires skill and is poorly defined and understood. When much of the process of design consists of optimisation of performance within a well defined domain, the use of artificial intelligence techniques may reduce or remove the need for human interaction in the design process. The automation of human processes allows round-the-clock operation at a faster throughput. Achieving a speedup would permit greater exploration of the possible designs, improving understanding of the domain. This thesis presents work that relates to three facets of the efficiency of numerical modelling: minimizing simulation execution time, controlling optimization processes and quantifying comparisons of results. These topics are of interest because simulation times for most problems of interest run into tens of hours. The design process for most systems being modelled may be considered an optimisation process in so far as the design is improved based upon a comparison of the test results with a specification. Development of software to automate this process permits the improvements to continue outside working hours, and produces decisions unaffected by the psychological state of a human operator. Improved performance of simulation tools would facilitate exploration of more variations on a design, which would improve understanding of the problem domain, promoting a virtuous circle of design. The minimization of execution time was achieved through the development of a Parallel TLM Solver which did not use specialized hardware or a dedicated network. Its design was novel because it was intended to operate on a network of heterogeneous machines in a manner which was fault tolerant, and included a means to reduce vulnerability of simulated data without encryption. Optimisation processes were controlled by genetic algorithms and particle swarm optimisation which were novel applications in communication cable design. The work extended the range of cable parameters, reducing conductor diameters for twisted pair cables, and reducing optical coverage of screens for a given shielding effectiveness. Work on the comparison of results introduced ―Colour maps‖ as a way of displaying three scalar variables over a two-dimensional surface, and comparisons were quantified by extending 1D Feature Selective Validation (FSV) to two dimensions, using an ellipse shaped filter, in such a way that it could be extended to higher dimensions. In so doing, some problems with FSV were detected, and suggestions for overcoming these presented: such as the special case of zero valued DC signals. A re-description of Feature Selective Validation, using Jacobians and tensors is proposed, in order to facilitate its implementation in higher dimensional spaces.