Material challenges in the integration of radar sensors behind painted polymer vehicle components

Abstract

When integrating automotive frequency modulated continuous wave (FMCW) radar sensors for driver assistance systems into the vehicle, the radar sensor cover must be taken into account. Particularly metallic paints on polymer covers lead to high reflections, which impair the radar performance. Therefore, paint properties, which may influence the electromagnetic wave radiated by the sensor, have to be analyzed in realistic experimental setups. Within this paper we show by measurements around 80 GHz that the relative permittivity increases exponentially with increasing pigment volume concentration of the metallic pigments. In general, finer metallic pigments lead to higher relative permittivities. However, very fine pigments may agglomerate and therefore show behavior comparable to coarse pigments. In addition we could show that the type of painting method must be taken into account.