Design of a Broadband Comb-Line Array Antenna for Millimeter-Wave Radar Application

To achieve wide impedance bandwidth, the proposed comb-line antenna consists of trapezium matching structure, comb-line unit, slot and rectangular stub. Cutting Obliquely the connecting part with radiating element and opening a slit in the middle of comb-line element reduces the transverse currents greatly, which generate undesired radiation for cross-polarization. In addition, adding the rectangular stub introduces multiple resonance points and increases the vertical currents for co-polarization radiation. From the simulation results, the 12-element comb-line array antenna has an impedance bandwidth of 17.86 GHz (61.46 GHz-79.32 GHz) and relative bandwidth of 25.37%. The peak gain within the impedance bandwidth is 17.1dBi.