| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain accurate information to reliably avoid a collision of a vehicle by respectively emitting a radio wave toward the advancing direction and the ground surface, and detecting ground speed simultaneously when a distance and relative speed with an obstacle is detected. SOLUTION: A slot antenna 10 emits an electromagnetic wave by a burst signal. The electromagnetic wave is emitted in the advancing direction of a vehicle from an upper side slot 11a, and is emitted at an angleθtoward the ground surface G from a lower side slot 11b. A reflected wave from an advancing directional obstacle and the ground surface rejoins to the slot antenna 10. At this time, when one's own vehicle moves, the reflected wave becomes a frequency shifted signal by a Doppler effect according to relative speed with the obstacle, and a reflected wave from the ground surface G also becomes a frequency shifted signal according to ground speed. These signals are transmitted to a mixer 6 by a circulator 7. A signal processor 9 detects a distance between one's own vehicle and the obstacle, relative speed and ground speed from a beat frequency and delay time of a received signal.</p> |
