Etude, conception et développement d’antennes compactes pour les applications ULB.

Abstract

The objective of this work concerns the study, design and development of compact antennas for Ultra Wide Band (UWB) applications. This work is divided into two essential parts. In the first part, we have presented the theoretical study, characteristics of compact UWB antennas and generalities of UWB technology. We also detailed all the necessary points related to the terms of the UWB compact antennas such as, the bandwidth enlargement of the compact planar antenna, the different geometries of compact antennas and the iniaturization techniques. Then, a state of art on UWB compact antennas was carried out to show the different techniques that are used in compact UWB antennas. The second part of this work is dedicated to the study, development and practical realization of compact UWB antenna structures operating in the 3.1 GHz to 10.6 GHz band. Two different antenna types are studied therein. The first type is a compact hexagonal planar monopole antenna with rejected narrow bands characteristics. This fabricated antenna shows a good agreement between measured and simulated results in terms of radiation pattern and reflection coefficient. The second type is a slot antenna with two feeding types. A compact slot antenna is fed by microstrip line. In this antenna, a stepped slot has been integrated in the ground plane to obtain an ultra-wideband resonance. In order to reject frequency bands, L-shaped slots are etched in the ground plane. After the fabrication process of this antenna, we have compared the measured and simulation results, which were very probatory. The other antenna is fed by coplanar wave guide (CPW) to achieve circular polarization. Both types of antennas have a very compact size compared to other antennas in the literature.