Detection in collision avoidance radar using active versus passive phased arrays

This paper presents two designs for phased arrays for collision avoidance radar operating at the 76 GHz band. The two designs for the antenna use a linear waveguide horn array that is fed with a waveguide power-dividing network and is tapered to produce low side-lobe levels for low-error detection. The taper is based on a 40-dB Taylor distribution. The first design uses passive phased arrays that are stacked and bore-sighted in different directions to produce scanned beams through switching. The second design uses a single phased array with MEMS phase shifters embedded in the last stage of the waveguide power divider. The phase shifters are integrated with the help of MIC/MMIC-to-waveguide or waveguide-to-coplanar-waveguide (CPW) transitions that are housed in the waveguide sections that feed the array elements. The antenna and detection system measurement results of the passive array design are presented, along with the simulation results of the active array design.