Miniaturisation et intégration d'antennes imprimées pour systèmes communicants ULB pulsés

摘要

This thesis is part of the project MIMOC (Methods of Integration and Miniaturization of communicating objects), which was completed in partnership with the laboratory IM2NP of Marseille, the company InsightSiP in Sophia Antipolis and Orange Labs La Turbie. The project targets the pulse transmission systems over a very wide band frequency spectrum (Ultra Wide Band signals : UWB). Within this project, the work of this thesis is focused on the development, miniaturization and integration of antennas for UWB communications systems conform to United States (FCC : 3.1 - 10.6 GHz) and European standards (ECC : 6 - 8.5 GHz). The antenna was developed by adjusting the various parameters which influences its matching and radiation. We led a preliminary study to create a database that was useful later in various phases of the project to modify the antenna to fit in its environment changes. A printed radiating element constituted by several rectangular layers, fed by ground coplanar waveguide line (GCPW), matched to the FCC frequency band, served as the basis for this study. This antenna has been studied in two configurations corresponding to two types of applications : credit card and USB key, mainly distinguished by the width of their ground planes. The study began with a large ground plane structure that was miniaturized in a second phase. The miniaturization aimed to reduce the width of the ground planes by changing the geometry of the structure to keep its radio-electrical performances. Several techniques have been studied, including reducing the size by 2D and 3D folding. The most effective technique was the one based on the insertion of slots in the side ground planes as well as in the lower ground planes. A well optimized dimension of these slots has achieved a structure 5 times smaller with a good impedance matching over all the FCC frequency band. These structures were then fabricated and the prototypes have been characterized. The characterization of the prototypes was obtained after several measurement campaigns in the LEAT and Orange Labs La Turbie. A test bench has been fully developed and measured in time and frequency domains. It permits us to extract the performances of antennas : gain, radiation pattern, impulse response, fidelity factor, etc... The capacity of a transmission through these prototypes was tested in a real environment. High data rate up to 500Mbits/s was obtained. The third phase of the work was to model a UWB chip pulse generator and integrate it together with the antenna in the system. This study was performed in the ECC band. A new printed miniature element with a good matching in this frequency band had to be designed. The chip has been fully modeled and parameterized, so it is taken into account in the design of the system. MIMOC project was completed successfully. The good partnership with all members has been very constructive and has achieved the co-design of the antenna and the microelectronics. Following this work, another project aiming to develop UWB communications systems operating in contact with the human body (RUBY) has just started.