The PhD work is carried out at the Laboratory of Electronics, Antennas and Telecommunications in the frame of a millimetre detection system in the used for two projects. The INFRADAR Project in collaboration with companies (ATE and Opéra Ergonomie) aims to conceive a flying assistance system for helicopters in order to avoid obstacle as high voltage power line and pylons at long range. The Sakura Project in collaboration with a foreign institute LEAT, (Electronic Navigation Research Institute of Tokyo) is focused on the Foreign Object and Debris detection (FOD) on airport runways. The first chapter is a state of art of millimetre radar and antennas. The chosen antenna for our application is a reflectarray. The second chapter is dedicated to the study of originals elementary cells that allow polarisation conversion and frequency stability. The chapter three describes the three developed reflectarrays with circular polarisation, simultaneous multi-beam operation and low noise radiation level. The chapter four talks about the several measurements campaigns carried out in Tokyo and Sendaï for the Sakura Project. The results will be compared to a theoretic model to define the system limitation. Finally, we discuss in the chapter 5 about the measurements carried out at Aix en Provence and Sophia Antipolis in the framework of the INFRADAR Project. This latter being just started the first results underline the detection capacities for our application.
