Horn and lens antenna with a small antenna substrate and high production tolerance for 77-GHz automotive long-range Radar

An antenna composed of a pyramidal horn and a dielectric lens with a small antenna substrate and high production tolerance for 77-GHz long-range radar was investigated. By employing a new horn-to-microstrip transition with a single microstrip antenna incorporated in the input aperture of the pyramidal horn, the antenna could be connected to monolithic microwave-integrated circuits (MMICs) using a microstrip line. This structure enables integration of the antenna and MMICs on the same surface of an antenna substrate, which reduces material and production costs. A fabricated antenna had an antenna gain of 23.5 dBi, where the size of the antenna substrate was less than 20 x 20 mm. The antenna had half-power beamwidths of 4.5 degrees and 16 degrees in elevation and azimuth, respectively. Moreover, the horn-to-microstrip transition was designed to provide robustness against misalignment of the horn and the microstrip antenna due to mechanical deviation during mass production. Measurement results showed that the antenna gain was degraded by less than 0.2 dB and that the beam was tilted less than 0.6 degrees and 0.7 degrees in elevation and azimuth, respectively, where the horn was misaligned to the microstrip antenna by 0.1 mm. (c) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.