Unambiguous target direction finding methods for automotive millimeter-wave radar

The paper considers and compares the parameters of radar antenna systems built according to the conventional structure with the phase shifters both in the transmitting and receiving antenna arrays and a radar, in which signal processing is performed only on the receiving side. The second case requires orthogonality of the transmitted signals. The radar characteristics with three transmitting and four receiving antennas are compared. Two types of the virtual antenna system are considered. The first one is a linear regular antenna array. The second one is the sparse array with the same number of antennas. For the second type, it is possible to implement a radar with a better angular resolution. The features of used radars as sensors for vehicle safety systems with a wide-angle view are considered. Possibility of the false target acquisition was noted. A method for unambiguous direction finding is proposed.