Analysis of EM wave scattering from asphalt and its application to automotive radar

Abstract

The driver’s safety is one of the problems that is considered by modern vehicle technologies. Many accidents occur due to extreme weather conditions, such as snow or freezing rain. Such weather causes decreases in the friction of the road surface, which cause danger for drivers in this kind of area. To improve the driver’s safety, ADAS (Advanced Driver Assistance Systems) can be used to recognize different road surface conditions and warn the driver to avoid them. To do this, ADAS needs to perform classifications on the surface, and radars operating above 77 GHz have shown potential for this kind of task. The polarimetric information of the surface is needed as the prior knowledge for radar to perform the classification properly, which can be obtained from the scattering of the surface. The scattering properties of the asphalt surface at 76 GHz is a complex problem and it is difficult to have a comprehensive solution. In the existing research, there is no research that used a full-wave numerical approach with a simulation model for the kind of problem in the 76 GHz frequency band. In this thesis, a numerical model is developed in the electromagnetic software suite FEKO to simulate asphalt surface scattering. The model considers surface roughness, dielectric medium, source polarization, and incidence angles for scattering from the asphalt surface. Based on the model simulations, statistical analysis is performed using the Monte Carlo method. The results of the model in the case of an RMS height of 2 mm and correlation length of 2mm show that for a very rough surface, the RCS of the surface decreases as the incidence angle is larger, and the value of the two polarization components is close to each other. By verifying the numerical model with SPM theory, it has been shown that the designed model can give accurate results in the designed scenarios, which proves that the designed model can be used for investigate rough surface scattering properties.