Analysis of Electromagnetic Wave Propagation along Rough Surface by Using Discrete Ray Tracing Method

The electromagnetic wave scattering by rough surfaces has attracted researchers’ attention from technical view point of radar cross section in relation to remote sensing technology [1], [2]. Recently, a rapid progress has been made in the area of sensor networks to gather physical data and to control natural environments. Sensors are usually distributed on terrestrial surfaces such as deserts, vegetable fields, hills and forests and so on. These surfaces are considered to be random rough surfaces, and thus it is important to investigate propagation characteristics along random rough surfaces to promote sensor networks. [3], [4]. As far as 1D rough surfaces are concerned, analyses based on ray tracing method (RTM) [3] and FVTD method [4] have been reported so far. However, the former method requires much computation time to search many reflection and diffraction rays, and the latter needs much computer memory to deal with relatively large area of rough surfaces compared with the wave length. In this paper, we propose discrete ray tracing method (DRTM) to numerically analyze electromagnetic wave propagation along 1D rough surface as shown in Fig. 1 as well as along 2D rough surface as shown in Fig. 2. In the present DRTM analyses, we have made some assumptions in order to simplify ray searching algorithm to save computation time. Numerical calculations are carried out for 1D and 2D random rough surfaces, and electric field distributions are shown to check the effectiveness of the proposed DRTM.