The researches of this thesis are divided into two parts. One is to investigate the applicability of ANSI C63.5 in high frequencies of 1 GHz to 6 GHz. In general, the Standard Site Method (SSM) of C63.5 is usually used to calculate the antenna factors for the calibration of broadband antennas. Through the theoretical calculations, the numerical simulations and measurements, we found that the discrepancies between the calibrated results of horizontal and vertical polarization related to the un-dipole-like pattern in higher frequencies. Furthermore, we analyzed the relations of the antenna factors, the heights of receive antennas and the radiation patterns. We also found that the predicted calibration results can be close to the practical ones by including the effects of radiation patterns. The other research is to study the issue about the ground plane size of a test site. The ground plane size of a qualified test site must be larger than the minimum size defined by C63.7. For this reason, we provide a method which combines the tilted antennas measurement with a trapezoid shape ground. By using this method in the smaller ground size, we can obtain the measured results close to those obtained in the larger ground size. This method can effectively reduce the required ground size and then decrease the installation cost of a test site. Meanwhile, this method can be applied for both of the horizontal and vertical polarizations.

<p>In this report we describe simulation of the surface current density on a PEC cylinder and the diffracted field for a line source above a finite PEC ground plane as a means to verify the Nero2D program. The results are compared with the exact solution and give acceptable errors. A terrain model for a communication link is studied in the report and we simulate the wave propagation for terrain with irregular shapes and different materials. The Nero2D program is based on the fast multipole method (FMM) to reduce computation time and memory. Gaussian sources are also studied to make the terrain model more realistic</p>

In this report we describe simulation of the surface current density on a PEC cylinder and the diffracted field for a line source above a finite PEC ground plane as a means to verify the Nero2D program. The results are compared with the exact solution and give acceptable errors. A terrain model for a communication link is studied in the report and we simulate the wave propagation for terrain with irregular shapes and different materials. The Nero2D program is based on the fast multipole method (FMM) to reduce computation time and memory. Gaussian sources are also studied to make the terrain model more realistic

In this study, we establish a car body PEC model by using a NEC-2-based numerical software. Based on this model, we then carry out a series of simulations and analysis in the FM band concerning the effects of various car structures on antenna patterns. The results have been compared with those available in open literature in order to verify our model. The simulation results show that the roof support pillars significantly affect the antenna patterns. We investigate the ripples caused by the finite ground plane in the antenna patterns, and propose a new edge treatment technique. Our results indicate that a significant reduction of these unwanted ripples can be obtained, if the proposed technique is applied. The effect of car glasses and human body is also taken into consideration. At last, the issue of studying the effects at higher frequencies is addressed. Two approaches are used, including UTD, and PO. Satisfactory results are obtained.

The power/ground plane structure within an electronic system not only delivers power, but also provides return path for the currents associated with the propagating signals. The cavity resonances within the power/ground plane structure affect the signal integrity of the system at high frequencies. The chip complexity and clock speed continue to increase and new structures, such as meshed planes and electromagnetic bandgap structures, are used in plane pair structure design. The signal integrity analysis of the power/ground plane structure becomes exceedingly important and challenging.The primary goal of this research is an in-depth investigation of the impact of the cavity resonances associated with the plane pair structure on the signal integrity. This includes development of modeling, simulation, and measurement methodologies for accurate and efficient characterization or prediction of the time/frequency domain electrical characteristics of power/ground plane pair structures. This research is divided into three parts. First, new SPICE compatible models are proposed for the new structures, such as the meshed plane and EBG embedded plane pair designs, so that the power/ground plane designs with these new structures can be simulated efficiently. Second, the accuracy of the simulation results is vital. The behavior of the benchmark structures is simulated and simulation results are verified either experimentally or by comparing with those from tools that are proven to be accurate. Third, high frequency measurement data is vulnerable to all parasitic parameters. The factors that affect the accuracy of measured data are investigated and methods to improve the accuracy of the measured data are proposed and verified.

No description available.

Este trabalho apresenta um estudo do efeito do substrato em transistores SOI de camada de silício e óxido enterrado ultrafinos (Ultra Thin Body and Buried Oxide - UTBB). A análise do trabalho foi realizada baseando-se em modelos teóricos, simulações numéricas e medidas experimentais. Experimentalmente pode-se notar que a presença do plano de terra (Ground Plane, GP) abaixo do óxido enterrado elimina e/ou minimiza alguns efeitos indesejados do substrato, tais como a variação do potencial na terceira interface (óxido enterrado/substrato). A densidade de armadilhas de interfaces (Nit) foi um parâmetro importante no ajuste da simulação para se obter curvas de corrente de dreno (IDS) em função da tensão de porta (VGF) e em função da tensão de substrato (VGB) similares às experimentais. As densidades de armadilhas de interface da primeira e da segunda interface foram ajustadas para o valor de 2x1011eV-1cm-2 depois de analisadas as curvas experimentais. Assim, a partir dessas simulações pode-se notar que o modelo usado no simulador era compatível com os resultados experimentais, com erro menor que 10%. Observou-se que o modelo analítico de efeito do substrato proposto por Martino et al. para transistores SOI totalmente depletados com camadas de silício mais espessas (acima de 40 nm) pode ser utilizado para dispositivos UTBB SOI de canal longo (10 m) até a segunda interface (camada de silício/óxido enterrado) entrar em inversão, quando o modelo perde a validade. Utilizando o modelo analítico também foi possível determinar os valores de tensão de substrato máximo (VGBmax) e mínimo (VGBmin), que determinam a tensão que, aplicada no substrato, mudam o estado da terceira interface de inversão para depleção (VGBmin) e de depleção para acumulação (VGBmax). Os valores de VGBmax variaram de 0,57 V à 0,75 V e os de VGBmin de -0,08 V à -3,39 V. O modelo analítico utilizado tem uma concordância ainda maior (menor que 10%) para transistores de canal curto (L=70 nm) em relação ao de canal longo (L=10m), provavelmente devido ao acoplamento eletroestático de fonte/dreno e 6 canal que posterga a formação da camada de inversão da terceira interface, ampliando a faixa de validade do mesmo. Por meio das simulações numéricas também foi possível analisar a concentração de elétrons ao longo do canal do transistor. Observou-se que a condição de polarização da terceira interface (óxido enterrado/substrato) tem grande influência no comportamento da segunda interface (camada de Silício/óxido enterrado) e da primeira (óxido de porta/camada de Silício) nos transistores UTBB SOI. Quando a terceira interface (óxido enterrado/substrato) está em acumulação, a primeira interface possui uma concentração de elétrons menor que a segunda interface, caracterizando assim, uma condução maior pela segunda interface. O simulador também foi utilizado para analisar o potencial interno do transistor ao longo da profundidade. Foram feitas simulações com e sem GP e variando-se a temperatura de operação dos transistores. Foi observado que quanto maior a temperatura de operação, os efeitos do substrato são minimizados devido à diminuição do nível de Fermi. Com a presença do GP a queda de potencial no substrato é praticamente zero enquanto nos dispositivos sem GP variam entre 0,2V e 0,6V. Como nos dispositivos com GP a queda do potencial no substrato é praticamente zero, a queda nos óxidos aumentou em relação aos dispositivos sem GP, podendo causar problemas de confiabilidade. / This work presents a study of the substrate effect on Ultra Thin Body and Buried Oxide (UTBB) SOI transistors. The work analysis was performed based on theoretical models, numerical simulations and experimental measurements. Experimentally, it is possible to notice that the presence of the ground plane implantation (GP) below the buried oxide eliminates and/or minimizes some undesirable effects of the substrate, as the variation of potential drop on third interface (buried oxide/substrate). The interface trap density (Nit) was an important parameter on simulation adjustment to obtain drain current curves as function of front gate bias and back gate bias close to the experimental. The interface trap density of the front and back interface were adjusted to the value of 2x10¹¹ e V-1 cm-2 after the experimental curves were analyzed. So from these simulations, it can be verified that the model used in the simulator was compatible with the experimental results, with error < 10%. It is noted that the analytic model proposed by Martino et al. to analyze the substrate effect for fully depleted SOI transistor with thicker silicon thickness (above 40 nm) is useful for UTBB SOI devices with long channel (L=10 m) until the back interface reach the inversion, when the model is no longer valid. Using the analytic model, it was also possible to determine the values of VGBmax and VGBmin, which represents the back voltage required to change de third interface from inversion to depletion mode (VGBmin), and the depletion to accumulation mode (VGBmax). The value of VGBmax ranged from 0,57 V to 0,75 V and for VGBmin ranged from -0,08 V to -3,39 V. The analytic model has more agreement for short channel (L = 70nm) transistor than the longer one (L = 10m), probably due to the electrostatic coupling between de drain/source and the channel that delays the formation of inversion channel on third interface extending the validity range of the model. By the numerical simulation, it was possible to analyze the electron concentration along the transistor. It was observed that the mode of the third 8 interface influences directly the condition of the back and front interfaces on UTBB SOI transistor. When the third interface is in accumulation mode, the front interface has an electron concentration lower than the back interface, so the current flows mainly on the back interface. This makes the value of the front threshold voltage is less than the analytic model, once the model is valid only if while the back interface is on depletion mode. The numerical simulation was also used to analyze the potential drop on SOI transistor. Simulation was performed with and without GP and varying the temperature. It was observed that for higher temperature, the substrate effect was minimized dur to the decrease of the Fermi level towards the mid-band. With GP, the substrate potential drop is almost zero, while on devices without GP it changes from 0,2 V to 0,6 V For devices with GP the potential, as the drop on substrate is almost zero, the potential drop on front and buried oxide increases, which can causes reliability problems.

To teleoperate an unmanned vehicle a rich set of information should be gathered from surroundings.These systems use sensors which sends high amounts of data and processing the data in CPUs can be time consuming. Similarly, the algorithms that use the data may work slow because of the amount of the data. The solution is, preprocessing the data taken from the sensors on the vehicle and transmitting only the necessary parts or the results of the preprocessing. In this thesis a 180 degree laser scanner at the front end of an unmanned ground vehicle (UGV) tilted up and down on a horizontal axis and point clouds constructed from the surroundings. Instead of transmitting this data directly to the path planning or obstacle avoidance algorithms, a preprocessing stage has been run. In this preprocess rst, the points belonging to the ground plane have been detected and a simplied version of ground has been constructed then the obstacles have been detected. At last, a simplied ground plane as ground and simple primitive geometric shapes as obstacles have been sent to the path planning algorithms instead of sending the whole point cloud.

This thesis condenses open public space on an urban site in order to create an animated environment for public use. Maximizing use of an open lot in Sao Paulo, Brazil, an elevated concrete plate layers the site into a covered plaza below with sport and recreation program above. By lifting a programmable ground surface above street level, the project maintains the ground plane as an extension of the urban surroundings. The underside of the elevated plate becomes a horizontal elevation, or sixth façade, which is the new public interface of the project. Essentially a double-sided surface that is formally manipulated, the elevated structure both defines and unifies the two zones, mediating between them while creating different conditions and atmospheres, each with their own potential to invite public activity.

Simulation and experiments quantify the effect of moving a horizontal dipole antenna close to a metal ground plane. Solutions to the radiation problems are offered.