A novel 77 GHz circular polarization slot antenna using ridge gap waveguide technology

In this paper, a novel circular polarization (CP) slot antenna using ridge gap waveguide (RGW) technology for 77 GHz automotive application is presented. The circular polarization character is achieved by the cooperation of the rotated rectangle slot realized on the upper plate and the metal ridge in the lower plate. The simulated 3-dB axial ratio (AR) bandwidth of this antenna is from 75-80 GHz. And the impedance bandwidth of this antenna is from 74 GHz to 83 GHz for |S11|<;-10 dB. Moreover, a 1×4 linear slot array is also designed, and its simulated results show that the proposed antenna array has an impedance bandwidth from 74 GHz to 83 GHz for |S11|<;-10 dB, and an AR bandwidth from 75 GHz to 79.8 GHz for AR<;3 dB. In addition, it exhibits a peak gain of 13.5 dBi, and the gain is more than 12.8 dBi over the AR bandwidth.