Single Layer Dual Circularly Polarized Antenna Array Based on Ridge Gap Waveguide for 77 GHz Automotive Radar

A single layer 77 GHz dual circularly polarized (CP) antenna array is proposed based on ridge gap waveguides (RGWs) technology. The antenna consists of eight U-shaped slots, fed by two feeding networks for generation of dual CP. The proposed antenna array has been fabricated and measured. The experimental results show good agreement with the simulations. The axial ratio is below 2 dB, and the return loss and port isolation are better than 13 and 18.6 dB over 76–81 GHz, respectively. The measured gain for the integrated array is 14.8 dBi at the center frequency of 78.5 GHz. With integration of feeding networks and the radiating elements in a single layer, this antenna has potential to be used in automotive radars.