Abstract: The invention relates to an assembly for a vehicle that detects a target object in the environment of the vehicle. The assembly includes a radar sensor with at least one transmit antenna and at least two receive antennas, an arrangement of layers including (i) a primary layer arranged facing the radar sensor with an exit surface for return radar waves, and (ii) at least one secondary layer with an entry surface for return radar waves, and (iii) at least one predetermined non-planar form present in the primary layer or in at least one secondary layer. The exit surface of the primary layer is computed on the basis of the at least one predetermined form such that return waves reach the at least two receive antennas with the same angle of incidence regardless of the position of the target object.