Modelisation et realisation de nouvelles antennes dielectriquqes larges bandes pour les communications sans fil

Abstract

In this work, we propose contribution to modeling, designing and fabricating new dielectric resonator antennas for wireless applications. The first part is devoted to the theoretical study of the characteristics of this type of antennas, including conical forms, modes of operation and feeding techniques, and the description of the finite differences in the time domain (FDTD) method. Then, this method (FDTD) and two other simulation software ( CST Microwave Studio and Ansoft HFSS ) are used to calculate the electromagnetic characteristics of a new stacked dielectric resonator antenna proposed to operate at the frequency band allocated by the Federal Communications Commission (FCC) for Ultra Wideband (UWB) applications, this band is between 3.1 GHz and 10.6 GHz. The second part of this thesis is focused on the practical implementation of the dielectric resonator antennas for wireless systems. The first fabricated antenna consists of a U-shaped resonator fed by an electric printed monopole. This antenna operates in the UWB spectrum and shows an omni-directional radiation pattern. Finally, two original structures that incorporate two hybrid antennas (dielectric / metal) are designed and manufactured. The two structures -proposed for cognitive radio (CR) applications, detection of weapons systems and medical imaging systems -show a transmission coefficient less than -20 dB, which allows an efficient integration.