WO 2006/005546 A1 discloses a generic device for fastening a sensor assembly, especially a radar sensor, which device is a moulded part arranged behind a bumper of a motor vehicle by means of a collar surrounding at least part of said sensor assembly, wherein said collar consists of a material that absorbs radar radiation. In addition to its electrical shielding effect, said collar largely prevents dirt, moisture and particles from accumulating on the sensor assembly. Furthermore, said known collar can be made of a flexible material in order to reduce or absorb mechanical stress on the sensor assembly, which may occur during normal and intended use as well as in case of a less severe collision, and to prevent mechanical vibrations from being transferred. Moreover, said known collar can be placed immediately next to the bumper and may even serve as a sensor holder.
It has shown, however, that said known device for fastening a radar sensor assembly, i.e. by means of a collar, does not provide optimum protection of said sensor assembly.