Study On Electromagnetic Modeling And Simulation Of Digital Map Based On Parabolic Equation

In the modern society, the radio-wave propagation is a main way for the information transmission, the analysis of wave propagation characteristics has important reference value for the engineering application, such as mobile communication, wireless device and so on. Complex geography environment is one of the main factors those have influence on wave propagation characteristics, the influences include two aspects:one side, terrain fluctuation leads to multipath propagation phenomenon, and generates the shadow area because of the terrain masking. On the other side, with the change of the propagation path, the change of the surface electromagnetic parameter influences the reflection coefficient, which affects the wave propagation characteristics, so study the wave propagation in the complex geographical environment has a great significance.Parabolic equation takes into account the wave diffraction and refraction, and has been widely used in the study of the wave propagation in the troposphere, so this paper is mainly focused on the modeling of complex geographical environment based on the parabolic equation model, studies the terrain-grid subdivision technology based on the digital elevation model and the modeling of the surface electromagnetic environment. On this basis, this paper simulates and analyzes the wave propagation characteristics in complex geography environment. The main works in this paper are as follows:Firstly, this paper studies the GeoTIFF format of the digital elevation model (DEM) to extract the terrain data from it. Considering the need of calculation of the parabolic equation model, this paper studies the two-dimensional and three-dimensional terrain-grid subdivision technology. At last, this paper introduces the terrain fluctuation information into the parabolic model to analyze the wave propagation characteristics in the real terrain.Secondly, high-resolution geographic image can be clearly observed the distribution of the surface environment, so this paper uses the geographic image to realize the classification of the surface environment. This paper uses an image segmentation algorithm to classify the geographic image’s regions, which combines the spatial relationships and the color feature. In order to introduce the information of the surface environment into the parabolic equation model, this paper marks the classified regions to realize the classification of the surface environment. As the same time to consider the need of calculation of the 3D parabolic equation model, this paper does the grid subdivision to the surface environment. At last, the different surface environment is given the different electromagnetic parameter to realize the modeling of the earth’s surface electromagnetic environment.Finally, this paper uses the DEM data and the geographic image to build the complex geography model that not only includes the terrain information but also includes the surface electromagnetic information. Then, this paper uses the 3DPE model to predict the wave propagation characteristics in the case that the surface environment respectively is the single geographical environment, integrated geographical environment and the PEC. The results show that the different geographical environment has different effects in the wave propagation and the predicted result has a difference. This paper provides a feasible method to study the wave propagation characteristics in the complex geographical environment, it has reference value for the practical engineering application.