An antenna device for a radar sensor, including: at least one first antenna array that is situated on a surface of a substrate and that includes a defined number of planar antenna elements connected in series; at least one second antenna array that is situated on the surface of the substrate and that includes a defined number of planar antenna elements connected in series; a feed line that is connected at the center of each of the two antenna arrays; with the aid of the feed line a feed signal being feedable into the antenna array in such a way that a feed signal that is phase-shifted by 180 degrees with respect to the second antenna array is suppliable to the first antenna array.