Ridge Gap Waveguide Slot Antenna Array with Ultra-low Sidelobe Level for Millimeter-Wave Automotive Radar Applications

In this paper, a ridge gap waveguide (RGW) slot array antenna is proposed for 77GHz automotive radar applications. By adjusting the size of the radiation slot, the antenna achieves an ultra- low sidelobe level (SLL) characteristic in H-plane. The unequal power divider with high power ratio is realized by using the structure of discontinuous ridge. The weak coupling approach is used to design the feeding network where the output ports are large power ratios and small phase differences to achieve the ultra- low SLL characteristics of the antenna E-plane. The antenna has a reflection coefficient better than -10dB in the 77-79.3GHz frequency band, and the gain is greater than 22 dBi. The simulated SLLs for both E-plane and H-plane is less than -27 dB in the operating band. The ultra-low SLL antenna array has great application potential in millimeter wave long-range automobile radar system.