Metamaterial matching of high-permittivity coatings for 79 GHz radar sensors

Future automotive radar sensors in the 79 GHz regime are intended to be integrated behind painted, plastic fascia. This integration has to be carefully studied, concerning reflections coming from the bumper in line of sight of the sensor. To reduce these reflections, impedance matching of multilayer structures with high permittivities (e.g. metallic paints) is mandatory. Besides conventional matching techniques, metamaterials are a possibility to realize a matching layer. Based on an adopted parameter extraction algorithm for multilayer dielectrics, a bandwidth evaluation of a possible metamaterial design is shown. The measurement results show that for a bandwidth up to 3.8 GHz the metamaterial outperforms the benchmark.