Caract\'erisation \'electromagn\'etique de milieux h\'et\'erog\`enes naturels - Application \`a la mesure de l'humidit\'e du sol par radiom\'etrie micro-onde

The work which we present takes place within the framework of mission SMOS of the ESA which will consist to send a radiometer (1.4 GHz) in space. The goal of the research which we propose is the improvement of the comprehension of the effects of structure soil and litter. The effects of the litter and heterogeneities of the ground are probably important but still are very ignored. So we developed an experimental approach in laboratory and in situ. That makes it possible to take measurements for various configurations (frequency, temporal, polarization, incidence, Bi-statics, Brewster effect...) and in term of surface conditions(homogeneous or heterogeneous ground, more or less wet, presence of litter...). Measurements at the laboratory with waveguide enabled us to characterize the various components of the geological structure (ground, rocks) and to check the model of Dobson usually used.