Research on Electromagnetic Wave Propagation Prediction for Advanced Ubiquitous Information Communications

在未来先进的泛在信息通信中，无线通信有望采用更高的频率，而周围环境的细节会影响电磁波的传播。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。通过我们的调查，发现射回射线法（SBR）是实现这一目的的有力工具。SBR方法是一种高频方法，它将离散的辐射射线从天线跟踪到传播空间，并在周围建筑物的角落经历反射和传播，并在墙壁和衍射处发生衍射。由于不可能考虑到所有多个散射过程，因此必须找到一种有效的算法来从中提取主导贡献。研究发现，在室外高频传播环境中，直接波、多次反射波和一次边缘绕射波对总场有重要影响，而在室内高频传播环境中，多次反射波和透射波对总场有重要影响。特别注意的是通过有损耗的介电介质（如混凝土墙壁）的光线追踪，在那里必须找到传播方向的适当定义。波的传播是难以理解的，因为我们看不到它。我们还研究了电磁场量的可视化方法，如电、磁、能量流矢量场，通过着色和图形化表示。

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.