Modelling of Rain Clutter Based on Empirical Data for Automotive Radar Validation

Simulation of precipitation for automotive radar validation requires suitable rain-clutter models to test radars against various weather conditions. Although there have been developments in the investigation of attenuation due to rain, rain back-scattering needs to be explored more. However, the analytical modelling is challenging. Even if the raindrops are considered perfect conducting spheres, the Rayleigh approximation cannot be used to calculate RCS since rain droplets are comparable to automotive radar wavelengths. Therefore, reflectivity measurements at different rain rates were conducted in an indoor rain facility. Based on the measured data, reflectivity from rain back-scattering for automotive radars is modelled using an empirical approach. The results indicate that reflectivity can be modelled using a gamma distribution parameterised by rain rate.