Transmission ellipsometry is governed by the transmission ellipsometric function (TEF) of a film-substrate system. The function can be analyzed through a series of constant-thickness contours and constant-angle-of-incidence contours in the complex plane. It has been observed that these TEF contours for a zero film-substrate system bear strong resemblances to the families of curves that make up the Smith chart for transmission lines. In this thesis we present a comparative study of the TEF and the Smith chart, specifically through the distinct similarities of their respective families of curves. It is shown that both TEF and Smith chart have similar contours in both the positive and negative imaginary half planes. The Smith chart’s contours originate from a complex plane with linear boundaries. It is bisected into symmetric positive and negative imaginary half planes of equal areas that are conjugate of each other. When transformed to the Smith chart, it is normalized and the conjugate relationship remains intact. All contours in the positive imaginary half plane of the Smith chart are symmetric to all of the contours in the negative half plane of the Smith chart. TEF contours originate from a non-complex reduced thickness plane. This plane has a non-linear upper boundary. It is bisected into two equal areas but non-symmetric, half planes. When transformed to the complex τ plane, the likeness of the constant-angle-of-incidence contours and constant-thickness contours to the Smith chart contours become a function of the material indices. As the film-substrate systems material indices are increased, the range of the non-linear boundary of the ф – dr plane is reduced and the TEF contours more closely resemble the Smith chart.

The VSWR is an important entity when assessing the properties of an antenna. This report presents measurements of the VSWR, related to antennas, by means of a Vector Network Analyzer. The open/short/load calibration method is used as a preparation before the actual measurement in order to obtain accurate results. The way that the VSWR depends on frequency is illustrated by three measurment methods: direct measurement of the VSWR, by using 𝑆11, or by using the Smith chart. The results are compared and conclusions are drawn.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-20T17:56:56Z No. of bitstreams: 1 luisguilhermedasilvacosta.pdf: 5093972 bytes, checksum: 6380895e21a76520d3f4a10aad5a3371 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-24T16:50:02Z (GMT) No. of bitstreams: 1 luisguilhermedasilvacosta.pdf: 5093972 bytes, checksum: 6380895e21a76520d3f4a10aad5a3371 (MD5) / Made available in DSpace on 2017-04-24T16:50:02Z (GMT). No. of bitstreams: 1 luisguilhermedasilvacosta.pdf: 5093972 bytes, checksum: 6380895e21a76520d3f4a10aad5a3371 (MD5) Previous issue date: 2012-02-24 / Atualmente, há um grande interesse no desenvolvimento de transceptores PLC (power line communication) para a transmissão banda larga e banda estreita de dados visando, sobretudo, aplicações smart grids e de acesso banda larga. Para o avanço da tecnologia PLC, há grande demanda pela introdução de acopladores com características e desempenhos que viabilizem a conexão dos tranceptores PLC `as redes de energia elétrica, com o mínimo de distorção possível. Neste contexto, a presente contribuição versa sobre o estudo, a investigação, especificação, projeto e análise de acopladores capacitados para transceptores PLC SISO (single input single output) banda larga e banda estreita. Para tanto, são introduzidos acopladores PLC nas seguintes faixas de frequências: de 9 kHz `a 2 MHz, de 1,7 MHz `a 100 MHz e de 1,7 MHz `a 150 MHz. As análises dos projetos e dos protótipos dos acopladores, concebidos para operar nas referidas bandas, mostram as dificuldades encontradas para garantir que as especificações de projeto sejam atendidas quando os componentes passivos são comerciais e a faixa de frequência de operação do acoplador aumenta. Além disso, as análises confirmam a necessidade de consideração de técnicas de prototipação de placas de circuitos impresso para sinais de frequência elevada. Finalmente, os resultados de medição mostram que os acopladores para baixa frequência discutidos podem ser utilizados em sistemas de medição de canais PLC. / Currently, there is a great interest to develop power line communications (PLC) transceivers for broadband and narrowband data communications for smart grids and network access. However, for advancing PLC technologies, there is a great demand for introduction of couplers for connecting the PLC tranceivers to the electric energy circuits with minimum distortion. This contribution addresses the study, investigation, specification, design, and analysis of capacitive couplers for single input single output (SISO), broadband and narrowband PLC transceivers. Capacity and SISO PLC couplers covering the following frequencies bandwidth are addressed: from 9 kHz up to 2 MHz, from 1,7 MHz up to 100 MHz and from 1,7 MHz up to 150 MHz. The analysis performance of the designed and prototyped PLC couplers for operating in the aforementioned frequencies bandwidths, shows the inherent difficulties to guarantee that the design specifications are fulfilled when passive components are commercial ones and the frequency bandwidth increase. Additionally, the analysis confirms the need for taking into account advancing prototyping techniques for dealing with high-frequency signals. Finally, the measurements show that the discussed narrowband PLC couplers can be used in a PLC channel system.