| 摘要 |
<p>PURPOSE:To momently and accurately detect the direction and the distance of an obstacle in the front of a vehicle by calculating a ratio signal of signals of two directions inputted from a pair of two-feed beam antennas which receive reflected beams from the obstacle. CONSTITUTION:Two-feed beam antennas 3a and 3b have two directional patterns A1 and B1 and two directional patterns A2 and B2 respectively,a nd therefore, azimuth angles theta1 and theta2 formed between two-feed beam antennas 3a and 3b an obstacle 5 are detected by reception signals of two-feed beam antennas 3a and 3b. Since a distance L between this pair of two-feed beam antennas 3a and 3b is known, a distance R between a vehicle 6 and the obstacle 5 is calculated by trigonometry. Though the azimuth angle theta1 of the obstacle cannot be accurately determined at the time of variance of the transmission output, the azimuth angle theta1 of the obstacle is determined with a high precision based on the ratio signal because this ratio Ib/Ia is fixed independently of the transmission output.</p> |
