梯形隧道中电磁波传播近场区分界点研究

Study on division point of near-region propagation mechanisms within trapezoid tunnel

为了精确描述梯形隧道中电磁波传播特性,运用Fresnel区域理论和几何向量知识,推导出隧道中分界点计算公式,结合软件模拟,具体分析了近场区分界点位置与收、发天线高度之间的关系。结果表明:在梯形隧道中,与隧道顶部相比,发射天线位于隧道垂直中间位置时,分界点距离最大;分界点距离和信号频率有关,随着载波频率的增加,分界点距离逐渐增大。

To accurately describe propagation characteristics of electromagnetic wave in trapezoid tunnel,the Fresnel zone theory and geometry vector are employed to deduce the calculation formulas of the division point in trapezium-shaped roadway,combined with software simulation,the relationship between the division point of the near-region and height of the antenna in trapezium-shaped roadway is analyzed intuitively.The results show that the distance of the point is larger when the transmitting antenna is located at the vertical middle of the tunnel comparing to the top of the tunnel.And the division point distance is related to the signal frequency,the point distance gradually increases with the carrier frequency.