Beam Squint Suppression of Series-Feed Microstrip Patch Antenna for Automotive Radar

The structuarl model of the series-feed microstrip patch antenna used in automotive radar usually exhibits beam squint issues, which significantly reduce the radar's perception capability. However, there is traditionally no effective design method to suppress beam squint. In this communication, a novel series-feed microstrip patch antenna design method is proposed to suppress beam squint. The method is termed as the amplitude-phase adjustment (APA) method, as it involves the adjustment of the amplitude and phase of each array element. The methods of element division, element equivalent, and element analysis are employed in the treatment of the series-feed microstrip patch antenna. Combining the characteristics of the series structure, the adjustment values of the patch width of each array element and the length of its corresponding transmission line are obtained. After the adjustment is completed, at 77 GHz, the beam squint angle of the linear array radiation pattern has been reduced from -1.60 degrees (based on the traditional method) to -0.01 degrees (based on the APA method). The simulation and measurement results of the manufactured series-feed microstrip patch antenna exhibit excellent consistency. Furthermore, the proposed series-feed microstrip patch antenna helps to enhance the perception ability of automotive radar.