Feeding Analysis of a 79 GHz Phased Microstrip Antenna Array for Autonomous Vehicle Radar Applications

Automotive radar is known as a promising sensing technology in autonomous vehicles due to its reliability. In current autonomous vehicles, the 77 – 81 GHz frequency band is the principal operating band for automotive radars. For the efficient operation of automotive radars, the radar antenna needs to be highly accurate. However, higher operating frequencies may present challenges in radar antenna design, requiring high gain, wide bandwidth, and low sidelobe levels (SLL). To address this issue, this study aims to adapt a planar series-fed linear antenna array to 79 GHz automotive radar applications using three different grounded coplanar waveguide (GCPW) feed configurations, including coplanar gap source port, vertical ground bridge, and wave port. Simulations were conducted to evaluate the performance of the antenna with the feed configurations. According to the results, it was shown that the antenna with wave port feed achieved the best impedance bandwidth (>3 GHz), whereas the antenna with either the coplanar gap source port or the vertical ground bridge configurations exhibited better main lobe phase centering and a higher gain (>18.4 dBi), with an acceptable SLL below -16.28 dB. It is believed that these findings may contribute to the development of high-performance radar antennas for next-generation autonomous vehicles.