Design of a Broadband Low Sidelobe Comb-Line Array Antenna

A broadband low sidelobe comb-line array antenna for millimeter-wave (MMW) automotive radar applications is proposed. The conductance is determined using unit simulation method. To reduce the transverse current flows on the over-width radiating element, the width of the connecting part with the feeding line in the radiating element is narrowed.For the problem that the resonance of the over-width unit is not obvious, the slot is opened for the middle unit. The final realized $1 \times 12$ array antenna has an impedance bandwidth of 75.35-79.47 GHz, an absolute bandwidth of 4.12 GHz and a relative bandwidth of 5.35%, which is 2.6 GHz higher than the conventional standing wave comb array. The peak gain within the impedance bandwidth is 14.67dBi, and the sidelobe level (SLL) is below −20dB within the impedance bandwidth, with stable gain characteristic.