Bandwidth Enhanced Array Antenna with Low Sidelobe for mm-Wave Automotive Radar Applications

An eight-element microstrip series-fed array antenna is proposed for millimeter (mm)-wave automotive radar applications. The proposed antenna consists of eight radiating elements and nine pairs of parasitic elements, which is fabricated on the thin single-layer dielectric substrate. The excitation of each radiating element adopts a Chebyshev distribution to realize a low sidelobe level. And the excitation amplitudes are modified by changing the width of each radiating element and the distance between neighboring radiating elements. Meanwhile, a wide impedance bandwidth is realized by introducing several parasitic elements around the radiating elements. To verify the performance of the proposed antenna, the antenna has been fabricated and tested. Experimental results display that the 10-dB impedance bandwidth for the antenna is 5.82% (75.40-79.92 GHz) with a low sidelobe of -15.5 dB.