Analysis and empirical modeling of rain clutter 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 further. However, the analytical modeling 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 modeled using an empirical approach. The results indicate that reflectivity can be modeled using an inverse-gamma or inverse-Weibull distribution parametrized by rain rate, and that the observed distribution varies with the spatial range considered, highlighting the impact of range-dependent effects on rain clutter modeling.