Antenna device for a radar detector, which has a circuit board having an electrically insulating substrate, on which a respective electrically conductive layer is arranged on each of two opposing sides, wherein the layer of at least one first side is configured as at least one main antenna. According to the invention, in addition to the at least one main antenna in each case, at least one antenna structure is provided which is integrated with the substrate, wherein each antenna structure integrated with the substrate comprises: a plurality of cutouts which are formed in the substrate and arranged in a waveguide and in each of which an electrically conductive material is arranged at least partially, and a feeder cable formed by the electrically conductive layer of one of the sides for feeding an electromagnetic wave into the antenna structure integrated with the substrate.