In this thesis, we propose the method to design tag antennas, which are suitable for radio frequency identification system. The fact that the tag antennas design comes with single layer printed circuit board can achieve cost down of the antennas. For the tag antennas, the aim is to design the RFID tag antenna operating in 860¡V960 MHz which are suitable for both the near- and far-field operations worldwide. The method we use to design tag antenna is the dual loop form with Bow-tie antenna, and we focus on the impedance conjugate matching between the RFID strap and antenna to increase impedance bandwidth and improve reading performance. We can adjust parameter to be suitable for different RFID strap in the design framework. The dual loop structure carries out power coupling efficiently in the near field and can allow the RFID strap to work even in the weak EM wave. According to the result of power coupling simulation, we analyze and discuss which factor will affect the reliability of the identification. Such reliability will help to build RFID system.

The operation speed of power delivery system of packages has been upgraded to GHz. The instant current will pass to the power plane of the mother board by way of the IC pins and result in electromagnetic wave propagation between the power plane and the ground plane, then to produce the programs of electromagnetic interference. In this thesis, we will analyze the EMI of power delivery system of packages by finite-difference time-domain in two dimensions structure in three sections. In firist section, to computing EMI in finite-difference time-domain in two dimensions structure. In second section, to analyze more complicated power delivery plane, ex: EBG, in finite-difference time-domain in two dimensions structure. In three section, to add property of capacitors on power plane to reduce EMI in two dimensions structure. Above all, we hope to built a fast computing method to compute EMI to solve the time-consuming problems of full-wave simulated software. And to supply the engineer to deal with the similar problems in packages efficiently.

This thesis presents detailed fuel spray investigations relating to an automotive Gasoline Direct Injection (GDI) pressure-swirl injector, employing a combination of numerical and physical analyses. The emphasis is placed on the near-nozzle in recognition that all later flow processes are dominated by this critical region. To enable the technology to maximise its potential, it is essential to further our understanding of the fundamental flow physics that govern the injection process, which remain largely unknown. The complexity of the spray process has led to many avenues of research. Simplified models are particularly suitable for parametric studies, allowing fast computation of some of the most important design parameters, such as nozzle discharge coefficient, cone angle and initial velocity. More complex methods such as Computational Fluid Dynamics (CFD) offer significantly more detail including the temporal and spatial evaluation of the flow field and fuel distribution, but at the cost of often lengthy computational time, and the need to tune models against physical evidence. Unfortunately none are able to describe all aspects of the injection event simultaneously. A considerable body of existing experimental data gathered under atmospheric conditions has been condensed and carefully presented to provide a comprehensive picture of injector operation. This comprises global spray performance data, spray imaging, and droplet velocity and size maps as a function of time after the Start Of Injection (SOl). These serve to provide a means to develop physical models and to correlate model predictions. Particular attention is drawn to the challenges faced by numerical methods to successfully predict the complex spray behaviour. A fundamental computational study employing the Volume Of Fluid (VOF) method describes droplet break-up under controlled conditions. By varying the Weber number of the flow the expected break-up mechanisms are recovered, and the numerics and case set-up tuned to offer a practical balance between the resource burden and solution accuracy. This paved the way to a detailed 3-D transient analysis of the near-nozzle region of a pressure-swirl injector. Computed results clearly identify the consecutive phases of the fuel spray development, from the initial unsteady jet through to the stable, swirling hollow cone formation. Comparison with experimental measurements revealed that the computational approach is able to capture the main qualitative features of the spray process.

La caractérisation des sources de rayonnement électromagnétique par des techniques de champ proche est aujourd'hui largement utilisée. Ces techniques consistent à mesurer le champ rayonné à proximité de la source pour en déduire, par traitement mathématique, le champ dans d'autres zones de l'espace (champ proche ou champ lointain). Les applications sont nombreuses comme par exemple la caractérisation des diagrammes de rayonnement des antennes ou la détermination des périmètres de sécurité autour des antennes de station de base. Par ailleurs, la mesure en champ proche trouve également des applications dans le diagnostic des sources.Ce travail de thèse porte sur une nouvelle méthode de calcul des coefficients du développement modal à partir d'une mesure sur une surface échantillonnée irrégulièrement ou arbitraire. Ces coefficients permettent ensuite d'évaluer le diagramme de rayonnement de la structure rayonnante dans toutes les directions de l'espace.Le principe de la méthode matricielle consiste à mesurer les composantes tangentielles du champ électromagnétique sur une surface. Les coefficients modaux sont obtenus par l'inversion d'un système d'équations linéaires reliant le champ électrique mesuré et les fonctions d'ondes.Cette méthode permet de désolidariser la géométrie de la surface de mesure du système de coordonnées dans lequel est exprimé le développement modal. Il en résulte de nombreux avantages, comme le choix d'une surface de mesure quelconque, pour des raisons de compacité, de simplicité de mise en œuvre ou de suppression d'erreur de troncature. / The characterization of electromagnetic radiation sources by near field techniques is now widely used. These involve measuring the radiated field close to the source to deduce, by mathematical processing, the field in other areas of space (near field and far field). There are many applications such as the evaluation of the antenna far field radiation patterns or the determination of safety perimeters around base station antennas. Furthermore, the near-field measurement technique can be used in the sources diagnostic.In our study, we present a new method for calculating the modal expansion coefficients from irregularly sampled or arbitrary measurement surfaces. The calculation of these modal coefficients allows the assessment of the radiation pattern of the antenna under test in every spatial directions.The principle of the matrix method is to calculate the modal coefficients by solving a system of linear equations relating the measured electric field and wave functions. Once the modal coefficients are known the far field of the structure is achieved.This method allows the separation between the geometry of the measuring surface and the coordinate system wherein the modal expansion is expressed. This leads to many advantages, such as selecting any measurement surfaces, for the reasons of compactness, implementation simplicity or truncation errors suppression.