Broadband Proximity‐Coupled Millimeter‐Wave Microstrip Array Based on SIW Feeding Network for Automotive Radar Applications

ABSTRACT This work presents a novel approach to broadband proximity‐coupled millimeter‐wave microstrip array design based on a substrate integrated waveguide (SIW) feeding network, tailored specifically to automotive radar applications. The antenna array includes a central microstrip line with a series of indirectly adjacent parasitic coupled trapezoidal patches periodically arranged on both sides. By precisely adjusting the gap between these parasitic patches and lines to control the normalized impedance of the radiating elements, it helps to achieve broadband and low sidelobe levels (SLLs) characteristics. To validate the proposed design, two antennas—a 1 × 16 linear array and an 8 × 16 planar array based on the SIW feeding network—are developed to operate within the 77‐ to 81‐GHz range. The measured SLLs are lower than −20 dB, with measured gains exceeding 15 dBi for the 1 × 16 array and 20 dBi for the 8 × 16 array across the 77‐ to 81‐GHz band. The impedance bandwidth of the 8 × 16 planar array reaches 6.8% (76.2 GHz–81.5 GHz).