Abstract: A wide beam, flat gain planar array antenna based on beamforming technology is designed for automotive angular radar systems. The array antenna consists of three 1×10 series feed line arrays, which are designed by Dolph-Chebyshev antenna synthesis method with unequal spacing distribution to reduce the side lobes. In order to satisfy the needs of the automotive angle radar wide field of view (FOV), the beamforming techniques are used for the planar array antenna to broaden the beamwidth of the azimuth plane and improve the flatness of the gain. The simulation and the measured results agree well. The measured results show that the 1×10 line array sidelobe level is −19.7 dB; the 3×10 planar array antenna has a 3 dB beamwidth of 106.4°, and the azimuth gain flatness range can reach ± 45°, the maximum gain is 11.3 dBi.