In this thesis, two types of handset antenna design respectively for dual-band GSM850/1900 operation and seven¡Vband LTE/WWAN operation are presented. The proposed antennas can achieve decreased antenna size and enhanced operating bandwidth by shaping the system ground plane of the handset. The seven-band LTE/WWAN antenna is printed on the system circuit board with good radiation characteristics and occupies a small size of 24.5 x 10 mm2. At first, we propose a half-loop antenna structure which integrates its facing edge of the system ground plane as the resonant path of the antenna. In this case, the required length of the half-loop antenna structure is only about a half compared with the traditional loop antenna. Next, to enhance the operating bandwidth of the antenna, a parasitic shorted monopole strip is added and a shaped system circuit board is used. The shaped system circuit board can integrate the battery with the circuit board to help reduce the thickness of handset. Also, much enhanced operating bandwidth for the lower band can be obtained, owing to the enhanced surface current excitation in the system ground plane resulting from properly shaping the system circuit board. Effects of the user¡¦s head and hand on the proposed antenna are studied, and the simulated SAR and HAC results are also analyzed for bio-compatibility issue.

The beginning of the 21 st century is characterised, among others, by the evolution in telecommunications. The rapid growth of mobile communications and the variety of applications proposed for the third generation (3G) systems require long operation time, low weight and cost for terminals, as well as improved link quality. For this reason a good efficiency and low profile antennas with low absorption losses by the user are desirable. The Planar Inverted-F Antenna (PIFA) is shown to result into low SAR values and high efficiency when operating in the proximity of the user. Despite these advantages, PIFA is also characterised by narrow bandwidth that limits its practical use. The first part of this work is dedicated to the measurements and evaluation of the radiation characteristics of the PIFA and other wire antennas both in the near and far fields. In addition, novel methods of PIFA tuning are presented. These include the repositioning of the shorting pin and modification of its capacitance. By using these techniques, the effective bandwidth of the PIFA can be increased to satisfy the GSM900 and DCS 1800 system bandwidth requirements. Dual-band and electronically tuned PIFA prototypes are also included. The effects of the handset size on the mass averaged Specific Absorption Rate (SAR), and antenna efficiency are investigated. The appropriate choice of handset can result in up to 30%-reduced peak SAR. The computed SAR values from PIFA are compared with those resulting from the use of a handset equipped with quarter wavelength monopole antenna. A new measure referred to as the 3dB SAR volume is proposed. This measure provides better understanding of the absorbed power distribution in the operator's head. Results obtained in the course of study show that low profile handset antennas, such as the PIFA, present in addition to dual resonance and low reflection losses, reduced SAR values, high efficiency and low 3dB SAR volume. Finally, SAR and 3dB SAR volume values from simulations on 5- and 10- years old child head models are compared with their equivalents for adult models from which appropriate conclusions are drawn.

Neste trabalho é apresentado o desenvolvimento de programa para cálculo de campos eletromagnéticos baseado no método das Diferenças Finitas no Domínio do Tempo (FDTD). O programa é aplicado no cálculo da Taxa de Absorção Específica (“Specific Absortion Rate” – SAR) em modelos de cabeça de adulto e criança usuários de telefone celular. Para a modelagem da cabeça da criança é feita análise detalhada das principais diferenças das características de cabeças de adulto e criança. Também é desenvolvido um programa para o cálculo do aumento de temperatura relacionado com a Taxa de Absorção Especifica. Os resultados são comparados com dados de outros autores, bem como com as normas relativas a níveis de exposição a ondas eletromagnéticas. / The development of software to compute the electromagnetic fields employing the Finite Difference Time Domain (FDTD) method is shown in this work. This software is used to estimate the Specific Absorption Rate (SAR) in head models of child and adult users of cell phones. A detailed analysis of the main differences between child and adult heads is made in order to model the child head. Software to compute the temperature rise related with the calculated SAR is also developed. The results are compared with results obtained by others authors, as well as with electromagnetic field exposure guidelines.

Nesta pesquisa é feita uma análise da interação do campo eletromagnético gerado por microcomputadores portáteis com o corpo humano, operando na faixa de radiocomunicações WI-FI, através da avaliação da taxa de absorção especifica (SAR). Os modelos de corpo humano heterogêneos utilizados são de um adulto de 34 anos e duas crianças de 6 e 11 anos os quais foram analisados em varias situações típicas de exposição à presença de um microcomputador portátil. Nas simulações dos cenários para avaliar a dosimetria foi utilizada a versão comercial do programa chamado SEMCAD X que é baseado no Método das Diferenças Finitas no Domínio no Tempo (FDTD). Da análise das simulações do modelo de corpo inteiro, o único resultado que ultrapassou a recomendação do (FCC, 1997) para 1 g de tecido foi na situação em que o microcomputador portátil, com a antena dipolo na parte posterior do teclado, está no colo do modelo de 34 anos. Numa segunda etapa, é feito um estudo teórico experimental da intensidade do campo elétrico gerado por dispositivos geradores de sinais Wi-Fi comerciais. Analisa-se à propagação de ondas eletromagnéticas através de paredes, utilizando uma antena monocone não ressonante e de banda larga, mediante o estudo e análise da sua taxa de onda estacionária. As medidas visam avaliar que projetando uma parede com uma espessura determinada consegue a propagação dos campos eletromagnéticos evitando reflexões e pontos quentes que possam produzir uma taxa de absorção maior no corpo humano presente nestes ambientes, além de caracterizar as propriedades dielétricas destas paredes. / This research analyses the interaction of the electromagnetic field generated by portable computers with the human body, operating in the range of radio Wi-Fi, by evaluating the specific absorption rate (SAR). The heterogeneous human body models used were those of a 34 years old adult and two children aged 6 and 11, were analyzed under various standard conditions of exposure to the presence of a portable microcomputer. The commercial version of SEMCAD X which is based on the Finite Difference Method in the Time Domain (FDTD) method was used in the simulations of the scenarios, to evaluate the dosimetry. The analysis of the simulation of the whole body model, the only result that exceeded the recommendation of the (FCC, 1997) for 1g of tissue was the simulation in which the dipole antenna on the back of the keyboard of the laptop resting on the lap of the 34-year old model. In the second stage, a theoretical experimental study was made of the intensity of the electric field created from Wi-Fi band signals generating devices. Subsequently, an analysis is made of the propagation of the electromagnetic waves through walls, using a non-resonant broadband monocone antenna by analyzing its voltage standing wave ratio (VSWR). The measures aim to assess that designing a wall with a given thickness, propagation of electromagnetic waves can be achieved, thus avoiding reflections and hot spots that can lead to higher SAR in the human body present in these environments, moreover to characterize the dielectric properties of these walls.

Nesta pesquisa é feita uma análise da interação do campo eletromagnético gerado por microcomputadores portáteis com o corpo humano, operando na faixa de radiocomunicações WI-FI, através da avaliação da taxa de absorção especifica (SAR). Os modelos de corpo humano heterogêneos utilizados são de um adulto de 34 anos e duas crianças de 6 e 11 anos os quais foram analisados em varias situações típicas de exposição à presença de um microcomputador portátil. Nas simulações dos cenários para avaliar a dosimetria foi utilizada a versão comercial do programa chamado SEMCAD X que é baseado no Método das Diferenças Finitas no Domínio no Tempo (FDTD). Da análise das simulações do modelo de corpo inteiro, o único resultado que ultrapassou a recomendação do (FCC, 1997) para 1 g de tecido foi na situação em que o microcomputador portátil, com a antena dipolo na parte posterior do teclado, está no colo do modelo de 34 anos. Numa segunda etapa, é feito um estudo teórico experimental da intensidade do campo elétrico gerado por dispositivos geradores de sinais Wi-Fi comerciais. Analisa-se à propagação de ondas eletromagnéticas através de paredes, utilizando uma antena monocone não ressonante e de banda larga, mediante o estudo e análise da sua taxa de onda estacionária. As medidas visam avaliar que projetando uma parede com uma espessura determinada consegue a propagação dos campos eletromagnéticos evitando reflexões e pontos quentes que possam produzir uma taxa de absorção maior no corpo humano presente nestes ambientes, além de caracterizar as propriedades dielétricas destas paredes. / This research analyses the interaction of the electromagnetic field generated by portable computers with the human body, operating in the range of radio Wi-Fi, by evaluating the specific absorption rate (SAR). The heterogeneous human body models used were those of a 34 years old adult and two children aged 6 and 11, were analyzed under various standard conditions of exposure to the presence of a portable microcomputer. The commercial version of SEMCAD X which is based on the Finite Difference Method in the Time Domain (FDTD) method was used in the simulations of the scenarios, to evaluate the dosimetry. The analysis of the simulation of the whole body model, the only result that exceeded the recommendation of the (FCC, 1997) for 1g of tissue was the simulation in which the dipole antenna on the back of the keyboard of the laptop resting on the lap of the 34-year old model. In the second stage, a theoretical experimental study was made of the intensity of the electric field created from Wi-Fi band signals generating devices. Subsequently, an analysis is made of the propagation of the electromagnetic waves through walls, using a non-resonant broadband monocone antenna by analyzing its voltage standing wave ratio (VSWR). The measures aim to assess that designing a wall with a given thickness, propagation of electromagnetic waves can be achieved, thus avoiding reflections and hot spots that can lead to higher SAR in the human body present in these environments, moreover to characterize the dielectric properties of these walls.

Neste trabalho é apresentado o desenvolvimento de programa para cálculo de campos eletromagnéticos baseado no método das Diferenças Finitas no Domínio do Tempo (FDTD). O programa é aplicado no cálculo da Taxa de Absorção Específica (“Specific Absortion Rate” – SAR) em modelos de cabeça de adulto e criança usuários de telefone celular. Para a modelagem da cabeça da criança é feita análise detalhada das principais diferenças das características de cabeças de adulto e criança. Também é desenvolvido um programa para o cálculo do aumento de temperatura relacionado com a Taxa de Absorção Especifica. Os resultados são comparados com dados de outros autores, bem como com as normas relativas a níveis de exposição a ondas eletromagnéticas. / The development of software to compute the electromagnetic fields employing the Finite Difference Time Domain (FDTD) method is shown in this work. This software is used to estimate the Specific Absorption Rate (SAR) in head models of child and adult users of cell phones. A detailed analysis of the main differences between child and adult heads is made in order to model the child head. Software to compute the temperature rise related with the calculated SAR is also developed. The results are compared with results obtained by others authors, as well as with electromagnetic field exposure guidelines.

Neste trabalho é apresentado o desenvolvimento de programa para cálculo de campos eletromagnéticos baseado no método das Diferenças Finitas no Domínio do Tempo (FDTD). O programa é aplicado no cálculo da Taxa de Absorção Específica (“Specific Absortion Rate” – SAR) em modelos de cabeça de adulto e criança usuários de telefone celular. Para a modelagem da cabeça da criança é feita análise detalhada das principais diferenças das características de cabeças de adulto e criança. Também é desenvolvido um programa para o cálculo do aumento de temperatura relacionado com a Taxa de Absorção Especifica. Os resultados são comparados com dados de outros autores, bem como com as normas relativas a níveis de exposição a ondas eletromagnéticas. / The development of software to compute the electromagnetic fields employing the Finite Difference Time Domain (FDTD) method is shown in this work. This software is used to estimate the Specific Absorption Rate (SAR) in head models of child and adult users of cell phones. A detailed analysis of the main differences between child and adult heads is made in order to model the child head. Software to compute the temperature rise related with the calculated SAR is also developed. The results are compared with results obtained by others authors, as well as with electromagnetic field exposure guidelines.

Nesta pesquisa é feita uma análise da interação do campo eletromagnético gerado por microcomputadores portáteis com o corpo humano, operando na faixa de radiocomunicações WI-FI, através da avaliação da taxa de absorção especifica (SAR). Os modelos de corpo humano heterogêneos utilizados são de um adulto de 34 anos e duas crianças de 6 e 11 anos os quais foram analisados em varias situações típicas de exposição à presença de um microcomputador portátil. Nas simulações dos cenários para avaliar a dosimetria foi utilizada a versão comercial do programa chamado SEMCAD X que é baseado no Método das Diferenças Finitas no Domínio no Tempo (FDTD). Da análise das simulações do modelo de corpo inteiro, o único resultado que ultrapassou a recomendação do (FCC, 1997) para 1 g de tecido foi na situação em que o microcomputador portátil, com a antena dipolo na parte posterior do teclado, está no colo do modelo de 34 anos. Numa segunda etapa, é feito um estudo teórico experimental da intensidade do campo elétrico gerado por dispositivos geradores de sinais Wi-Fi comerciais. Analisa-se à propagação de ondas eletromagnéticas através de paredes, utilizando uma antena monocone não ressonante e de banda larga, mediante o estudo e análise da sua taxa de onda estacionária. As medidas visam avaliar que projetando uma parede com uma espessura determinada consegue a propagação dos campos eletromagnéticos evitando reflexões e pontos quentes que possam produzir uma taxa de absorção maior no corpo humano presente nestes ambientes, além de caracterizar as propriedades dielétricas destas paredes. / This research analyses the interaction of the electromagnetic field generated by portable computers with the human body, operating in the range of radio Wi-Fi, by evaluating the specific absorption rate (SAR). The heterogeneous human body models used were those of a 34 years old adult and two children aged 6 and 11, were analyzed under various standard conditions of exposure to the presence of a portable microcomputer. The commercial version of SEMCAD X which is based on the Finite Difference Method in the Time Domain (FDTD) method was used in the simulations of the scenarios, to evaluate the dosimetry. The analysis of the simulation of the whole body model, the only result that exceeded the recommendation of the (FCC, 1997) for 1g of tissue was the simulation in which the dipole antenna on the back of the keyboard of the laptop resting on the lap of the 34-year old model. In the second stage, a theoretical experimental study was made of the intensity of the electric field created from Wi-Fi band signals generating devices. Subsequently, an analysis is made of the propagation of the electromagnetic waves through walls, using a non-resonant broadband monocone antenna by analyzing its voltage standing wave ratio (VSWR). The measures aim to assess that designing a wall with a given thickness, propagation of electromagnetic waves can be achieved, thus avoiding reflections and hot spots that can lead to higher SAR in the human body present in these environments, moreover to characterize the dielectric properties of these walls.

L'objectif de cette thèse est de traiter la problématique de la caractérisation et du traitement de la variabilité de l'exposition humaine aux ondes radio à travers l'utilisation de la dosimétrie numérique. En effet, si les progrès dans le domaine du calcul hautes performances ont contribué à significativement réduire les temps de simulation pour l'évaluation de l'exposition humaine, ce calcul du débit d'absorption spécifique reste un processus coûteux en temps. Avec la grande variabilité des usages, cette contrainte fait que la prise en compte de l'influence de paramètres d'entrée aléatoires sur l'exposition ne peut se faire par des méthodes classiques telles que les simulations de Monte Carlo. Nous proposons dans ces travaux deux approches pour répondre à cette problématique. La première s'appuie sur l'utilisation et l'hybridation de méthodes de construction de modèles de substitution afin d'étudier l'influence globale des paramètres d'entrée. La deuxième vise à l'évaluation efficace et parcimonieuse des quantiles à 95% des distributions de sortie et s'appuie sur le développement d'une méthode de planification d'expériences adaptative et orientée couplée à la construction de modèles de substitution. Les méthodes proposées dans ce manuscrit sont comparées et testées sur des exemples analytiques et ensuite appliquées à des problèmes concrets issus de la dosimétrie numérique / The purpose of this thesis is to deal with the problem of the management and the characterization of the variability of the human exposure to radio frequency waves through the use of the numerical dosimetry. As a matter of fact, if the recent advances in the high performance computing domain led to reduce significantly the simulation duration for the evaluation of the human exposure, this computation of the specific absorption rate remains a time-consuming process. With the variability of the usage, this constraint does not allow the analysis of the influence of random input parameters on the exposure to be achieved with classical approaches such as Monte Carlo simulations. In this work, two approaches are proposed to address this problem. The first one is based on the use and the hybridization of construction methods of surrogate models in order to study the global influence of the input parameters. The second one aims at assessing efficiently the 95th-percentiles of the output distributions in a parcimonous way. It is based on the development of an adaptive and oriented methodology of design of experiments combined with the construction of surrogate models. In this manuscript, the proposed methods are compared and tested on analytical examples and then applicated to full-scale problems from the numerical dosimetry

Les recherches en dosimétrie numérique non-ionisante ont connu des avancées considérables notamment grâce à la capacité de calcul croissante des ordinateurs. Ces dernières années, la prise en compte de la variabilité dans la dosimétrie est devenue un enjeu majeur. Les sources de variabilité sont nombreuses, parmi elles, les conditions d'exposition au rayonnement électromagnétique peuvent induire des doses absorbées très différentes. La modélisation de canal de propagation en environnement intérieur a permis d'avoir une connaissance précise des conditions d'exposition d'un corps humain plongé dans cet environnement. Cette thèse a pour but de développer une méthode statistique du calcul de la dose absorbée par le corps et d'adapter le modèle de canal stochastique à la dosimétrie. L'étude statistique de l'exposition a révélé la nécessité d'obtenir les valeurs de Débit d'Absorption Spécifique corps entier dans le cas d'expositions à une onde plane pour tous les angles d'incidence possibles. Compte tenu des temps de calcul particulièrement long en dosimétrie, une méthode d'interpolation efficace, le krigeage, des valeurs de Débit d'Absorption Spécifique a été mise en oeuvre. L'analyse de sensibilité aux paramètres du canal des moments du Débit d'Absorption Spécifique a permis de connaître l'impact de chacun de ces paramètres. Le modèle de canal a pu être simplifié et donc adapté à la dosimétrie tout en quantifiant l'erreur d'approximation qu'implique cette simplification. Cette thèse répond à l'enjeu de la prise en compte de la variabilité en dosimétrie dans un environnement complexe. / Research in non-ionizing numerical dosimetry has been improved thanks to high calculation capacity of computers. These years, integrating variability in the field of dosimetry has become a major issue. Sources of variability are numerous; among them, there are the exposure conditions to electromagnetic radiation which can lead to very different absorbed doses. Indoor channel modeling enables to have a deep knowledge of the exposure conditions of a human body located inside this indoor environment. The aim of this thesis is to develop a statistical method of calculation of the absorbed dose by the human body and to adapt the stochastic channel model to dosimetry. The statistical study of exposure reveals the need to obtain Specific Absorption Rate values for a plane wave exposure for all possible angles of incidence. Taking into account that computation in dosimetry is time consuming, an efficient interpolation method, kriging method, is implemented in order to get whole body Specific Absorption Rate values. Kriging method enables to obtain Specific Absorption Rate for all possible angles of incidence and then to calculate expectation and variance of Specific Absorption Rate. Sensitivity Analysis of expectation and variance to the statistical channel parameters reveals the impact of each parameter. The channel model has been simplified and then adapted to dosimetry by estimating the approximation error induced by this reduction. This thesis answers to the issue of integrating variability in dosimetry in a complex environment and develop the tools that open a new path in studying exposure in any complex environment.