摘要
本文用一致性几何绕射理论（简称ＵＴＤ），预测了频率为９００ＭＨｚ、１８００ＭＨｚ的窄带和宽带天线电波在隧道中的传播特性，并讨论了隧道的分支、弯曲障碍物对传播特性的影响．其中，窄带和宽带传播特性是分别在空域和时域中研究的。结果表明：在空直隧道中，不同边界条件对窄带信号具有各不相同的传播衰减率；宽带信号具有宽的相关带宽。在弯曲和有分支空隧道中传播衰减较高。在有车辆等障碍物的隧道中接收信号具有宽的相关带宽。在弯曲和有分支空隧道中传播衰减较高。在有车辆等障碍物的隧道中接收信号会有较大起伏、较长的均方根延迟和较高的附加损耗。理论计算结果与实测值非常相符。
The uniform theory of diffraction (UTD) is used to predict the narrow and wide band propagation characteristics in tunnels at both 900 and 1800 MHz frequencies. The narrow band propagation is characterized in spatial domain while the wide-band in time domain in the empty and obstructed tunnels. The computed results are in excellent agreement with measurements. The results show that there exists a distinct boundary with which the narrow band propagation exhibits different attenuation rates in straight and empty tunnel environments. The wide band propagation possesses broad coherent bandwidth. The propagation loss is higher in curved or branched tunnels, as expected. Obstacles, such as vehicles, cause more fluctuation in the received signal and thus result in larger varying RMS delay spreads and additional loss.
出处
《电子学报》
EI
CAS
CSCD
北大核心
1998年第12期26-30,共5页
Acta Electronica Sinica
基金
国家自然科学基金
