Analysis of the Effects of Rainwater Covered Bumper on the Automotive Radar Signals

This paper studies the effect of the rainwater covered bumper on the automotive radar signal. The rainwater on the painted bumper is modeled in two ways: continuous thin layer and droplets. In the continuous thin layer approach, a uniform water layer is considered on the painted bumper's surface. In contrast, for the droplet approach, multiple hemispheres with equal diameter and spacing are considered on the painted bumper's surface. Moreover, to replicate a real scenario, the presented study considers a water covered painted bumper near a radar antenna. Different cases are studied using the transmission coefficient, S-parameter, and gain parameters to analyze the effect of rainwater on the radar performance. Based on this study, it is found that the transmission through the continuous thin film of water is better than that of droplets. Also, this study aids in selecting the appropriate paint layer such that transmission through the bumper is significant.