| 摘要 |
<p>PURPOSE:To freely select the installation height of an antenna and to reduce the influence of reflection from a road surface and an unwanted reflecting object. CONSTITUTION:A radar device 4 is fitted to the bumper part of the front end of an automobile 1. The gain of the antenna is provided with a vertical directivity pattern 7. The vertical directivity pattern 7 is provided with gain characteristics proportional to cosec<2>theta relating to the angle of elevation theta so as to prevent the useless reflecting object such as an overpass and a tunnel ceiling, etc., from being detected thereafter to prevent erroneous operations from being performed. Thus, an object 6 from a certain height (h) can be detected with a certain reception strength regardless of a distance R and the inter-vehicle distance with the proceeding automobile 3 travelling on a road 2 or the like can be effectively detected.</p> |
