A Novel Method for Switching and Tuning of PBG Structures

Photonic band-gap (PBG) structures are utilized in microwave components as filters to suppress unwanted signals. In this work, rectangular perforations were created in the ground plane of a microstrip line to construct a PBG structure. A gold-coated alumina substrate was utilized to switch or tune the bandstop characteristics of this structure. It was demonstrated that the bandstop characteristics were switched off from - 35 to - 1 dB at 16 GHz. Tuning of the bandstop edge with a shift of 1.5 GHz was also shown

Enhancement of Microwave Properties of Planar Filters and Antennas using Photonic Bandgap (PBG) Structures

In this thesis, we explore the design, computation, and experimental analysis of photonic crystals, with a special emphasis on structures and devices that make a connection with practically realizable systems. First, we analyze the propenies of photonic-crystal: periodic dielectric structures that have a band gap for propagation. The band gap of periodically loaded air column on a dielectric substrate is computed using Eigen solvers in a plane wave basis. Then this idea is extended to planar filters and antennas at microwave regime. The main objectives covered in this thesis are:• Computation of Band Gap origin in Photonic crystal with the abet of Maxwell's equation and Bloch-Floquet's theorem • Extension of Band Gap to Planar structures at microwave regime • Predict the dielectric constant - synthesized dieletric cmstant of the substrates when loaded with Photonic Band Gap (PBG) structures in a microstrip transmission line • Identify the resonant characteristic of the PBG cell and extract the equivalent circuit based on PBG cell and substrate parameters for microstrip transmission line • Miniaturize PBG as Defected Ground Structures (DGS) and use the property to be implemented in planar filters with microstrip transmission line • Extended the band stop effect of PBG / DGS to coplanar waveguide and asymmetric coplanar waveguide. • Formulate design equations for the PBG / DGS filters • Use these PBG / DGS ground plane as ground plane of microstrip antennas • Analysis of filters and antennas using FDID method

Dispositivos planares integrados utilizando método dinâmico com metamateriais e PBG

This work presents a theoretical, numerical and computation analysis of parameters of a rectangular microstrip antenna with metamaterial substrate, fin line as a coupler and also integrated devices like integrated filter antenna. It is applied theory to full-wave of Transverse Transmission Line - TTL method, to characterize the magnitude of the substrate and obtain the general equations of the electromagnetic fields. About the metamaterial, they are characterized by permittivity and permeability tensor, reaching to the general equations for the electromagnetic fields of the antenna. It is presented a study about main representation of PBG(Photonic Band Gap) material and its applied for a specific configuration. A few parameters are simulated some structures in order to reduce the physical dimensions and increase the bandwidth. The results are presented through graphs. The theoretical and computational analysis of this work have shown accurate and relatively concise. Conclusions are drawn and suggestions for future work

Desenvolvimento de um ressoador retangular de fenda com múltiplas camadas de substrato e com utilização de material PBG para sistema de comunicação sem fio

In the globalized world modern telecommunications have assumed key role within the company, causing a large increase in demand for the wireless technology of communication, which has been happening in recent years have greatly increased the number of applications using this technology. Due to this demand, new materials are developed to enable new control mechanisms and propagation of electromagnetic waves. The research to develop new technologies for wireless communication presents a multidisciplinary study that covers from the new geometries for passive antennas, active up to the development of materials for devices that improve the performance at the frequency range of operation. Recently, planar antennas have attracted interest due to their characteristics and advantages when compared with other types of antennas. In the area of mobile communications the need for antennas of this type has become increasingly used, due to intensive development, which needs to operate in multifrequency antennas and broadband. The microstrip antennas have narrow bandwidth due to the dielectric losses generated by irradiation. Another limitation is the degradation of the radiation pattern due to the generation of surface waves in the substrate. Some techniques have been developed to minimize this limitation of bandwidth, such as the study of type materials PBG - Photonic Band Gap, to form the dielectric material. This work has as main objective the development project of a slot resonator with multiple layers and use the type PBG substrate, which carried out the optimization from the numerical analysis and then designed the device initially proposed for the band electromagnetic spectrum between 3-9 GHz, which basically includes the band S to X. Was used as the dielectric material RT/Duroid 5870 and RT/Duroid 6010.LM where both are laminated ceramic-filled PTFE dielectric constants 2.33 and 10.2, respectively. Through an experimental investigation was conducted an analysis of the simulated versus measured by observing the behavior of the radiation characteristics from the height variation of the dielectric multilayer substrates. We also used the LTT method resonators structures rectangular slot with multiple layers of material photonic PBG in order to obtain the resonance frequency and the entire theory involving the electromagnetic parameters of the structure under consideration. xviii The analysis developed in this work was performed using the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transverse to the real direction of propagation z), thus treating the general equations of the fields electric and magnetic and function. The PBG theory is applied to obtain the relative permittivity of the polarizations for the sep photonic composite substrates material. The results are obtained with the commercial software Ansoft HFSS, used for accurate analysis of the electromagnetic behavior of the planar device under study through the Finite Element Method (FEM). Numerical computational results are presented in graphical form in two and three dimensions, playing in the parameters of return loss, frequency of radiation and radiation diagram, radiation efficiency and surface current for the device under study, and have as substrates, photonic materials and had been simulated in an appropriate computational tool. With respect to the planar device design study are presented in the simulated and measured results that show good agreement with measurements made. These results are mainly in the identification of resonance modes and determining the characteristics of the designed device, such as resonant frequency, return loss and radiation pattern

Materiais supercondutores HTS para arranjos de antenas e aplicação de PBG para micro-ondas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Um estudo de estruturas com PBG e fotônica

One of the objectives of this work is the ana1ysis of planar structures using the PBG (photonic Bandgap), a new method of controlling propagation of electromagnetic waves in devices with dielectrics. Here the basic theory of these structures will be presented, as well as applications and determination of certain parameters. In this work the analysis will be performed concerning PBG structures, including the basic theory and applications in planar structures. Considerations are made related to the implementation of devices. Here the TTL (Transverse Transmission Line) method is employed, characterized by the simplicity in the treatment of the equations that govern the propagation of electromagnetic waves in the structure. In this method, the fields in x and z are expressed in function of the fields in the traverse direction y in FTD (Fourier Transform Domain). This method is useful in the determination of the complex propagation constant with application in high frequency and photonics. In this work structures will be approached in micrometric scale operating in frequencies in the range of T erahertz, a first step for operation in the visible spectra. The mathematical basis are approached for the determination of the electromagnetic fields in the structure, based on the method L TT taking into account the dimensions approached in this work. Calculations for the determination of the constant of complex propagation are also carried out. The computational implementation is presented for high frequencies. at the first time the analysis is done with base in open microstrip lines with semiconductor substrate. Finally, considerations are made regarding applications ofthese devices in the area of telecommunications, and suggestions for future

Aplicações de Dispositivos de Microondas utilizando Substrato EBG/PBG para Comunicações Móveis

The modern society depends on an efficient communications system able to of transmitting and receiving information with a higher speed and reliability every time. The need for ever more efficient devices raises optimization techniques of microstrip devices, such as techniques to increase bandwidth: thicker substrates and substrate structures with EBG (Electromagnetic Band Gap) and PBG (Photonic Band Gap). This work has how aims the study of the application of PBG materials on substrates of planar structures in microstrip, more precisely in directional quadrature couplers and in rat-race and impedance of transformers. A study of the planar structures in microstrip and substrates EBG is presented. The PBG substrates can be used to optimize the radiation through the air, thus reducing the occurrence of surface waves and the resulting diffraction edge responsible for degradation of radiation pattern. Through specific programs in FORTRAN Power Station obtained the frequencies and couplings for each structure. Are used the program PACMO - Computer Aided Design in Microwave. Results are obtained of the frequency and coupling devices, ranging the frequency band used (cellular communication and Wimax systems) and the permittivity of the substrate, comparing the results of conventional material and PBG materials in the s and p polarizations.

Aplicação do método LTT às estruturas retangulares e triangulares em multicamadas e empilhadas em substratos PBG para comunicações móveis

Recently the planar antennas have been studied due to their characteristics as well as the advantages that they offers when compared with another types of antennas. In the mobile communications area, the need for this kind of antennas have became each time bigger due to the intense increase of the mobile communications that needs of antennas which operate in multifrequency and wide bandwidth. The microstrip antennas presents narrow bandwidth due the loss in the dielectric generated by radiation. Another limitation is the radiation pattern degradation due the generation of surface waves in the substrate. In this work some used techniques to minimize the disadvantages (previously mentioned) of the use of microstrip antennas are presented, those are: substrates with PBG material - Photonic Bandgap, multilayer antennas and with stacked patches. The developed analysis in this work used the TTL - Transverse Transmission Line method in the domain of Fourier transform, that uses a component of propagation in the y direction (transverse to the direction real of propagation z), treating the general equations of electric and magnetic field as functions of y and y . This work has as objective the application of the TTL method to microstrip structures with single and multilayers of rectangular and triangular patches, to obtaining the resonance frequency and radiation pattern of each structure. This method is applied for the treatment of the fields in stacked structures. The Homogenization theory will be applied to obtaining the effective permittivity for s and p polarizations of the substrate composed of PBG material. Numerical results for the triangular and rectangular antennas with single layer, multilayers resonators with triangular and rectangular patches are presented (in photonic and isotropic substrates). Conclusions and suggestions for continuity of this work are presented

PBG-assisted shared-aperture dual-band aperture-coupled patch antenna for satellite communication

Design and development of a photonic bandgap (PBG)-assisted shared-aperture dual-band orthogonal aperture-fed rectangular microstrip patch antenna element, which is suitable for a portable very small aperture terminal (VSAT), are presented in this paper. The dual-band dual-polarized antenna element achieves 21% input impedance bandwidth at the S- and C-bands. A comparison of the antenna with and without 2D PBG grids shows that the inclusion of PBG structures (PBGSs) improves the antenna performances. (c) 2005 Wiley Periodicals, Inc.

Fractal PBG assisted co-planar waveguides

In general, conventional electromagnetic bandgap (PBGs) with uniform distribution show spurious ripples in pass-band and poor stop-band responses. This paper presents a detailed investigation in terms of pass-band and stop-band characteristics of uniplanar transmission line loaded with fractal shape PBGs. (c) 2005 Wiley Periodicals, Inc.

Immunoexpression of adrenergic receptors in detrusor from patients with prune belly syndrome: a digital quantification

Introduction: Prune belly syndrome (PBS) presents with large-capacity bladders, high compliance and post-void residual volumes. Operative and conservative treatments are controversial. When histologically compared to normal bladder, bladder outlet obstruction results in an up- or down-regulation of adrenoceptors. Our goal was to study the immunoexpression of adrenoceptors in detrusor from patients with PBS. Materials and methods: Bladder domes from PBS patients (n = 14) were studied (PBG). For normal controls, bladder specimens were obtained at adult surgery (n = 13) (CG1) and at child autopsy (n = 5) (CG2). Staining was performed using antibodies to alpha 1a, alpha 1b, alpha 1d and beta 3 adrenoceptors. Five to 10 images were captured on an optic microscope with a digital camera and analysed with Photoshop(R). The immunocyhistochemical index with arbitrary units was calculated and compared. Results: Mean age was 1.28, 64 and 1.41 years for PBG, CG1 and CG2, respectively. The immunohistochemical index with arbitrary units of alpha 1a receptors was 0.06 in PBG, 0.16 in CG1 and 0.14 in CG2 (p = 0.008); of alpha 1b 0.06, 0.06 and 0.07 (p = 0.781); and of alpha 1d 0.04, 0.04 and 0.05 (p = 0.618). Regarding beta 3 the respective values were 0.07, 0.14 and 0.10 (p = 0.378). Conclusion: Our results show a decrease in ala-adrenoceptor immunostaining intensity in detrusor from children with PBS. Further in vitro studies are needed to determine whether these observations are physiologically significant. (C) 2009 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Dor abdominal aguda como apresentação de porfirias

As porfirias são um grupo de oito doenças metabólicas raras, em resultado de uma deficiência enzimática em cada uma das oito enzimas envolvidas na biossíntese do grupo heme. São doenças maioritariamente hereditárias, mas podem também ser adquiridas aquando da exposição a certos fatores ambientais e/ou patológicos. Estes fatores externos, denominados de porfirinogénicos também têm um papel preponderante no diagnóstico das porfirias, uma vez que mimetizam os sintomas clínicos de um ataque agudo de porfiria, contribuindo para subestimar esta doença, levando a um atraso no diagnóstico e diminuído o sucesso do prognóstico. Os ataques agudos de porfiria, nomeadamente na porfiria aguda intermitente, porfiria variegata, coproporfiria hereditária, e deficiência da desidratase do ácido delta-aminolevulínico, apesar de serem doenças multissistémicas, têm em comum como apresentação clínica, a dor abdominal aguda. A pesquisa de porfobilinogénio (PBG) na urina, através da realização do teste de Hoesch, é uma forma rápida e fácil de excluir a suspeita clínica de porfiria. Pretendemos com este trabalho, alertar para a necessidade de um diagnóstico laboratorial atempado, que pela sua simplicidade poderá descartar ou confirmar se a dor abdominal aguda, tão frequente nas urgências hospitalares, será ou não uma manifestação clínica de um ataque agudo de porfiria. Este estudo contribuirá não só para aumentar o nosso conhecimento acerca destas doenças, como também permitirá uma melhor compreensão dos mecanismos de patogenicidade das porfirias, o qual ainda permanece pouco conhecido.

Estudo, Avaliação e Propostas de melhoria para a Climatização do edifício Biorama do Parque Biológico de Vila Nova de Gaia

A eficiência energética e a preocupação com a sustentabilidade têm vindo a ganhar preponderância na sociedade moderna. Este trabalho é uma contribuição para esta tendência onde se pretendeu avaliar e sugerir alterações ao sistema de climatização do edifício Biorama do Parque Biológico de Vila Nova de Gaia (PBG). Procedeu-se em primeiro lugar a uma caracterização física, química e geográfica dos 5 biomas constituintes do Biorama. Para isso, recorreu-se a documentos fornecidos pelo próprio PBG, visitas ao local e registo de medições de alguns parâmetros (temperatura, humidade relativa, qualidade do ar). Posteriormente foi realizado o balanço térmico dos edifícios, de acordo com a legislação em vigor, recorrendo a expressões e conceitos teóricos. Foram determinados valores dos ganhos térmicos de aquecimento de 15811, 10694, 7939, 9233, e 6621 kWh/ano para Floresta tropical, Mesozoico, Dunas, Savana e Deserto, respetivamente. Foram igualmente determinados valores dos ganhos térmicos no verão de 7093, 4798, 3560, 4144 e 2971 kWh na Floresta tropical, no Mesozoico, nas Dunas, na Savana e no Deserto, respetivamente. As cargas térmicas de aquecimento foram 149, 125, 47, 60 e 51 kW na Floresta tropical, no Mesozoico, nas Dunas, na Savana e no Deserto, respetivamente. As cargas térmicas de arrefecimento foram iguais a 59, 57, 47, 35 e 36 kW na Floresta tropical, no Mesozoico, nas Dunas, na Savana e no Deserto, respetivamente. Algumas soluções são avançadas, bem como alternativas comportamentais de modo a corrigir alguns problemas identificados. Uma proposta é a da instalação de painéis solares e acumuladores de calor, com os quais se estima um ganho médio conjunto de 500 W em cada bioma, e representam um investimento de 1050 euros e terão um retorno de 1 ano. Em relação à humidade é sugerido a utilização mais eficaz dos aspersores existentes e a utilização de esponjas, para fazer subir a humidade relativa para valores superiores a 80%. Em sentido inverso, no inverno, propõem-se a utilização de material higroscópico para fazer baixar a humidade relativa em cerca de 5%. Os custos com os suportes e o material higroscópico rondam os 250 €. Por fim, é sugerido a instalação de um aparelho de ar condicionado de 16 000 BTU no corredor de ligação, pois é a única forma de garantir condições de conforto térmico. Esta proposta de arrefecimento com ar condicionado e ainda o recurso a uma cortina de lâminas de plástico, que servem para efetuar uma separação mais eficiente entre ar frio e ar quente, têm um custo aproximado de 350 €. É ainda sugerida a utilização de lonas ou de uma planta trepadeira com um custo por planta de 5€, nas coberturas dos telhados virados a sul, sendo que a zona do corredor deverá ser totalmente coberta, a fim de evitar a exposição solar direta.

Avaliação do Desempenho Energético e da Qualidade do Ar Interior do Edifício Principal do Parque Biológico de Vila Nova de Gaia

A presente dissertação tem como principal propósito avaliar o desempenho energético e a qualidade do ar interior do edifício principal do Parque Biológico de Vila Nova de Gaia (PBG). Para esse efeito, este estudo relaciona os termos definidos na legislação nacional em vigor até à presente data, e referentes a esta área de atuação, em particular, os presentes no SCE, RSECE, RCCTE e RSECE-QAI. Para avaliar o desempenho energético, procedeu-se numa primeira fase ao processo de auditoria no local e posteriormente à realização de uma simulação dinâmica detalhada, cuja modelação do edifício foi feita com recurso ao software DesignBuilder. Após a validação do modelo simulado, por verificação do desvio entre os consumos energéticos registados nas faturas e os calculados na simulação, igual a 5,97%, foi possível efetuar a desagregação dos consumos em percentagem pelos diferentes tipos de utilizações. Foi também possível determinar os IEE real e nominal, correspondendo a 29,9 e 41.3 kgep/m2.ano, respetivamente, constatando-se através dos mesmos que o edifício ficaria dispensado de implementar um plano de racionalização energética (PRE) e que a classe energética a atribuir é a C. Contudo, foram apresentadas algumas medidas de poupança de energia, de modo a melhorar a eficiência energética do edifício e reduzir a fatura associada. Destas destacam-se duas propostas, a primeira propõe a alteração do sistema de iluminação interior e exterior do edifício, conduzindo a uma redução no consumo de eletricidade de 47,5 MWh/ano, com um período de retorno de investimento de 3,5 anos. A segunda está relacionada com a alteração do sistema de produção de água quente para o aquecimento central, através do incremento de uma caldeira a lenha ao sistema atual, que prevê uma redução de 50 MWh no consumo de gás natural e um período de retorno de investimento de cerca de 4 anos. Na análise realizada à qualidade do ar interior (QAI), os parâmetros quantificados foram os exigidos legalmente, excetuando os microbiológicos. Deste modo, para os parâmetros físicos, temperatura e humidade relativa, obtiveram-se os resultados médios de 19,7ºC e 66,9%, respetivamente, ligeiramente abaixo do previsto na legislação (20,0ºC no período em que foi feita a medição, inverno). No que diz respeito aos parâmetros químicos, os valores médios registados para as concentrações de dióxido de carbono (CO2), monóxido de carbono (CO), ozono (O3), formaldeído (HCHO), partículas em suspensão (PM10) e radão, foram iguais a 580 ppm, 0,2 ppm, 0,06 ppm, 0,01 ppm, 0,07 mg/m3 e 196 Bq/m3, respetivamente, verificando-se que estão abaixo dos valores máximos de referência presentes no regulamento (984 ppm, 10,7 ppm, 0,10 ppm, 0,08 ppm, 0,15 mg/m3 e 400 Bq/m3). No entanto, o parâmetro relativo aos compostos orgânicos voláteis (COV) teve um valor médio igual a 0,84 ppm, bastante acima do valor máximo de referência (0,26 ppm). Neste caso, terá que ser realizada uma nova série de medições utilizando meios cromatográficos, para avaliar qual(ais) são o(s) agente(s) poluidor(es), de modo a eliminar ou atenuar as fontes de emissão.