Computer Analysis Of The Urban Environment Of Electromagnetic Radiation

As the rapidly develop of the mobile communication technology in recent years, predicting the propagation characteristics for urban area has become an important subject. To accommodate more users with limited resource of frequency, new ceflular size will be much smaller, and it needs some new model to predict the propagation characteristic. At the same time, as more radio source built, electromagnetic pollution in urban area becomes more serious, which do harm to people's healthy and communication system. So it's necessary to simulate the propagation of radio source in urban area by computer.Some predicting models have been presented since 1970's, and in last ten years, more emphases were put on making propagation models, which can predict propagation characteristics for micro cellular radio.Most pvopagation models, which can be adapted to micro cellular are theory method based on ray tracing method. Experiment shows that ray tracing method can simulate the propagation characteristics of micro cellular in urban area exactly. But for the complicated condition of urban area, applying common ray tracing method needs more calculation and memory than the computer technology can get at now time. So we have to find a better way based on ray tracing method.In this paper, we present a new rapid ray tracing method----visible area available ray searching. Base on Geometry Optical Theory (GO) and Uniform Theory of Diffraction (UTD), by creating the visible facets&edges tree, this method can find all propagation paths from a transmitter to a receiver with high computation efficiency.Adopting the method mentioned above, we calculate a simple case about the diffraction of corner, and then compare the result with the published measurements. After that, the propagation characteristics for some tylncal environments in urban area are calculated and analyzed.