| 摘要 |
<p>PURPOSE: To evade the incapability of communication or the wrong communication caused by the waves reflected on the structures or passing vehicles at tallgate of an electronic toll collection system(ETCS). CONSTITUTION: An on-vehicle communication antenna 22, a roadside communication antenna 21 which performs the communication of accounting processing and a vehicle detector 320 which detects the vehicles included in a range wider than a communication area 350 are placed at a tallgate. An electromagnetic wave path decision part 150 acquires the shapes, positions, etc., of vehicles passing through the tollgate from a vehicle detection part 130, decides the electromagnetic wave paths formed by the direct and reflected waves and connecting the antenna 21 to the antenna 22 of each vehicle and calculates the receiving field intensity of each path. Then the path of the highest field intensity is selected as a 1st radiation direction with other paths selected as a 2nd radiation direction respectively among those vehicles included in the area 350 to decide a directivity pattern where the 1st radiation direction has the highest radiation intensity and the 2nd radiation direction is defined as a null point respectively. Then the radiation direction of an antenna unit 101 is controlled via a directivity control part 111.</p> |
