High-Density Implementation Techniques for Long-Range Radar Using Horn and Lens Antennas


IEICE TRANSACTIONS on Electronics   Vol.E104-C   No.10   pp.596-604
Publication Date: 2021/10/01
Publicized: 2021/03/12
Online ISSN: 1745-1353
DOI: 10.1587/transele.2021MMP0006
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technologies)
77 GHz long-range radar,  horn and lens antenna,  antenna isolation,  direction of arrival estimation,  compact implementation,  

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Long-range radars (LRRs) for higher level autonomous driving (AD) will require more antennas than simple driving assistance. The point at issue here is 50-60% of the LRR module area is used for antennas. To miniaturize LRR modules, we use horn and lens antenna with highly efficient gain. In this paper, we propose two high-density implementation techniques for radio-frequency (RF) front-end using horn and lens antennas. In the first technique, the gap between antennas was eliminated by taking advantage of the high isolation performance of horn and lens antennas. In the second technique, the RF front-end including micro-strip-lines, monolithic microwave integrated circuits, and peripheral parts is placed in the valley area of each horn. We fabricated a prototype LRR operating at 77 GHz with only one printed circuit board (PCB). To detect vehicles horizontally and vertically, this LRR has a minimum antenna configuration of one Tx antenna and four Rx antennas placed in 2×2 array, and 30 mm thickness. Evaluation results revealed that vehicles could be detected up to 320 m away and that the horizontal and vertical angle error was less than +/- 0.2 degrees, which is equivalent to the vehicle width over 280 m. Thus, horn and lens antennas implemented using the proposed techniques are very suitable for higher level AD LRRs.