Research on Electromagnetic Wave Propagation Prediction for Advanced Ubiquitous Information Communications

对于未来先进的泛在信息通信，人们预计会使用更高的频率进行无线通信，而周围环境的细节会对电磁波的传播产生影响。因此，无线接入点的正确安装需要有效的解析传播预测方法。我们的研究发现，射弹射线法(SBR)是实现这一目的的有力工具。SBR法是一种高频方法，它将离散的辐射线从天线追踪到传播空间，经历反射和透过墙壁以及周围建筑物角落的绕射。由于不可能考虑所有的多次散射过程，人们必须找到一种有效的算法来提取它们的主要贡献。研究发现，在高频室外传播环境中，直达波、多次反射波和初级边缘绕射波在总场中起着重要作用，而多次反射波和透射波是室内传播的重要组成部分。人们特别注意通过有耗介质(如混凝土墙)的光线跟踪，其中必须找到传播方向的适当定义。波的传播很难理解，因为人们看不到它。我们还研究了电场量的可视化方法，如电场量、磁场量、电磁场和电磁场等和能量流矢量场，通过上色和图形表示。

For future advanced ubiquitous information communications, it would be expected to use higher frequency for wireless communication, where detail surrounding environment would affect for electromagnetic wave propagation. Therefore effective analytical propagation prediction method should be needed for proper installation for wireless access points. By our investigation, Shooting and Bouncing Rays (SBR) method is found to be a powerful tool for such purpose.SBR method is one of the high frequency methods and discretized radiating rays will be traced from an antenna to the propagating space with experiencing reflections and transmissions through walls and diffraction at corners of the surrounding buildings. Since it would be impossible to take into account all multiple scattering processes, one has to find an efficient algorithm for extracting dominant contribution from them.It is found that direct, multiply reflected and primary edge diffracted waves play important roles to the total field for high frequency outdoor propagation environment, whereas multiply reflected and transmitted waves are important components for indoor propagation.Special attention has been made for ray tracing through lossy dielectric medium such as concrete walls, where the proper definition of the propagation direction has to be found.Wave propagation is difficult to understand since one cannot see it We have also studied visualization methods of the electromagnetic field quantities such as electric, magnetic, and energy flow vector field by coloring and expressing graphically.