Low-Profile Patch Array Antenna with Stable Beam for 77 GHz Automotive Radar Applications

A 2x8 patch array fed by substrate integrated waveguide (SIW) transverse slots was proposed for 77 GHz automotive radar applications. It is a multilayer structure which can be fabricated by printed circuit board (PCB) processing. Four 2x2 sub-arrays were linearly arranged and fed by a symmetrical SIW feeding network with excitation port in the middle space. stable beams in both xoz- and yoz-plane can be achieved benefiting from the symmetry of the feeding network. Good agreement between the simulation and measurement validates the correctness of this design. The proposed low-weight low-cost array antenna possesses an operation frequency band of 5%, a maximum gain of 15.8 dBi, an orthogonal polarization discrimination higher than 30 dB, a profile of 0.137 lambda(0), etc.