Relation between Discrete Points of DRTM and Diffraction Points

The field estimation is significantly important to design high performance radio communication network links such as mobile communication network system, digital TV broadcasting system, fire and disaster prevention wireless system and so on. We have developed and proposed discrete ray tracing method (DRTM) that enables us to estimate propagation characteristics along land surface structure. However the method still requires a certain time to compute field intensities in case of long path. We have studied to shorten computation time and to save computer memory by considering the discretization rate of the terrain surface with equal interval size of linear piece wise strips. We have realized that intense sampling points are needed at the edge point like a mountain summit to estimate the field intensities in shadow areas following the summit. In this paper, we consider the discretization rate at the mountain summit by checking accuracy of numerical results of electromagnetic (EM) wave analysis by DRTM compared with rigorous solutions given by the Bessel and Hankel functions.