| 摘要 |
<p>The antenna (22) is mounted on the roof of a vehicle and is directional, with gain provided to the left and right of the vehicle. The antenna has zero gain to the front and rear of the direction of travel of the vehicle. The antenna can also move in the azimuth direction. The antenna beam centre (21) is inclined at an upward angle, to avoid the vehicle roof area. The antenna properties allow communications paths perpendicular to the vehicle to be selected, reducing the returns from other vehicles.</p> |
