In this study, a novel wideband near-coupled millimeter-wave microstrip array antenna is proposed, specifically designed for 77-81 GHz medium- and long-range automotive radar applications.The antenna array comprises a microstrip line and series of rectangular and polygonal radiation units.These units are periodically distributed on both sides of the microstrip line and separated by approximately half of the guiding wavelength.The rectangular and polygonal radiation elements are designed to enhance excitation coupling.In addition, the impedance bandwidth is widened and out-of-band frequency is suppressed.Different radiation elements and rectangular reflection slots are matched to achieve the beam shaping effect and realize a flat shoulder radiation pattern.The normalized resistance of the radiation unit is controlled by adjusting the interval between the radiation unit and microstrip line.At the operating frequency range of 77-81 GHz, the gain of the array antenna exceeds 14 dBi, and the impedance bandwidth reaches 7.47%(76.5-82.4 GHz).An actual example was processed and tested, and the accuracy of the design was confirmed by simulations and actual measurements.