A 76-GHz antenna with highly-tapered aperture for collision avoidance systems

Vehicle-mounted radar systems for collision avoidance require receive antennas with scanned narrow beams in azimuth and a broad beam in elevation. This paper presents a pyramidal horn array of 32 elements, designed at 76 GHz with a 40-dB Taylor aperture distribution. A tightly spaced waveguide power divider provides the tapered distribution with adjusted waveguide lengths between the different stages in order to achieve the uniform phase in all paths. The last stage of the power divider uses equal power splits because of space limitations, which results in slightly higher side-lobes and low-level grating lobes. The fabricated array shows results that match the HFSS-simulated results.