Study Of Radio Propagation Based On Parabolic Equation

Along with the rapid development of high frequency radio technology, predicting characteristics of radio propagation in complex environments has become an important research subject. The accurate electromagnetic data of battlefield environments are absolutely necessary for constructing martial wireless systems such as radar-warning, electronic warfare, automatic command etc. In the process of marking out network, it need to avoid the existence of no-signal areas. So the study of propagation prediction in regions became an important task. As the development of mobile communication, the system has been chosen to satisfy the increasing requirement to the capacity of contemporary system for larger subscribers. On the other hand, the development of mobile communication brings more and more transmitters, which engender heavier electromagnetic pollution and side affects to human bodies. Consequently, it's necessary to analyze the propagation of EM wave. The article compute the loss of propagation with parabolic equation.Among the present radio propagation models, many models which based on ray tracing method can't deal with irregular terrain and complex atmosphere structures synchronously. So they can't predict the radio propagation characteristics in complex environments accurately. But the parabolic equation(PE) method which deduced from the wave equation can overcome the shortcoming, and so the PE model is the most precise one for predicting the radio propagation in troposphere. Accordingly, mainly based on the PE method, the dissertation studies the two-dimensional parabolic equation(2DPE) model which used to predict radio propagation on large size troposphere and the three-dimensional parabolic equation(3DPE) model which used to predict radio propagation in urban micro cells.This dissertation mainly focuses on the PE algorithms applied to the computation of electromagnetic scattering and propagation problems. The main studies are as following: It introduces two numerical solution, Split-Step-Fourier-Transform, the other is Crank-Nicholson, emphases on Crank-Nicholson. To conquer the precision problem, with the rotated method. It analyses the error of PE, and put forward method to improve it; we can get the initial fields with antenna directional map, it is more precise than traditional method.2-D and 3-D absorbing boundary conditions(Perfectly Matched Layer(PML) based on stretched coordinate) were analyzed and deduced carefully. They were not only applied to the computation of electromagnetic scattering, but also dealt with unbounded space electromagnetic wave propagation problems. To apply PE method to every medium, aim at different polarize situation deduce the impedance boundary condition in medium. Comparing several irregular terrain models, the most precise one at present is chosen. It simulate the familiar terrain and environment in the mobile communication, for example, ground,sea(combined with fractal),mountains and several buildings. Considering obvious error of scatters with edges, equivalent edge currents is presented in the paper to solve the problem, new parabolic equation model is constructed by using the electromagnetic potential function, Combine with the knowledge of NN and dynamic optimization method, study the best method to optimize the layout of base station.