Abstract
In the frame of outdoor meshed Wi-Fi network operating in the 2.4 GHz frequency band, we conceive sectoral antennas with very low front to back radiation ratio. This should limit co-channel interferences between neighboring base stations. We first study radiating elements in microstrip technology associated with a reflector based on metamaterials. The latter is based on the structure of Sievenpiper, the so-called "mushroom" structure. This structure comprises periodic pattern sprinted on a substrate. Simulations of the dispersion diagram and of the phase of the reflection coefficient, linked to numerous results from the literature, allow us to perform a full-through characterization of these reflectors. We can therefore propose a criterion on the geometry of the patterns bringing the high-impedance frequency band within the forbidden electromagnetic bandgap. The behavior of the overall antenna, radiant element and reflector, exhibits very interesting performances considering bandwidth and radiation lobes. For economic reasons, this structure is not retained and we switch to a simple perfect electric conductor plane. A part of this thesis explores the impact of printed antenna geometry and its associated reflector on the gain and front to back ratio characteristics. We finally choose a loop geometry. This work is achieved with 3D electromagnetic simulations and with outdoor measurements. On-field experiments on a prototype comprising 3 tri-sectoral antennas assembled under a Radome validate and concludes the study.