Systematic characterisation of scattering behaviour of natural (oceans, snow, sand) and manmade (roads...) rough surfaces is required in many radar applications. The scattering elements of such surfaces have complex geometry and are randomly distributed; so their radar scattering involves complex interactions. Moreover, in general, it is found that the overall scattering response of such surfaces is composed of surface (which is function of the surface height statistics) and volume scattering components (due to inclusions underneath the rough interface). During this thesis, we propose and set out rigorous analytical formulations to calculate the scattered power by rough surfaces : Integral Equation Method (IEM) is used to work out the surface scattering and the Radiative Transfer Theory (RTT) is applied to model the volume scattering. The applications of our work are focused on road surfaces such as asphalt and concrete. We studied the evolution of the monostatic scattering coefficients from the nadir to the hardly ever developed grazing incidence, even at millimeter-waves frequencies, in response to large requirements in modeling from remote sensing up to safety in road traffic. Then we evaluated the general bistatic scattering coefficients (scattering in the directions other than incidence direction). An other interesting stage of our work was focused on the evaluation of the behaviour of an object in its close environment. Actually, it is sometimes necessary to take into account the contribution of the coupling of the targets and their immediate environment. We developed a method which evaluates the Radar Cross Section (RCS) of target considering their immediate environment influence, using both the bistatic scattering coefficients from the target and the terrain around it.
Modelling of rough natural and manmade surfaces at millimetre-wave frequencies – study of the interactions between a target and its natural environment