Study Of Radiowave Propagation Characteristics Based On The Three Dimensional Scalar Parabolic Equation

With the rapid development of modernized radio communication technology, calculating characteristics of radio propagation in complex environments is a more and more significant research topic. Prediction models are the most important part. Although many researchers have been working hard during the past few decades in the area of field strength prediction, there are still numerous problems to be solved. A perfect propagation for the rational layout and make the best use of modern communication resource, the accurate electromagnetic information of the urban environments are very important references. Mobile communication, which is very important in the development of Military and telecommunication system, In the process of selecting network, it need to avoid the existence of no-signal areas. It is a very important task to analyze the loss of propagation prediction in regions. The system has been chosen to satisfy the increasing requirement of communication and the capacity of contemporary system for larger consumers. In addition, the development of mobile communication brings a large number of transmitters, which brings heavier electromagnetic pollution and side affects to the health of bodies. Therefore, it's necessary to analyze the propagation of electromagnetic wave. The dissertation computes the loss of radiowave propagation based on parabolic equations.This dissertation mainly focuses on the PE algorithms applied to the computation of electromagnetic propagation problems. The main studies are listed as follows: First, we introduce some knowledge about the electromagnetic wave propagations. Introduce several basic mechanisms of radiowave propagation. And describe the method to calculate the free-space radiowave propagation, transmission diffraction, refraction, reflection phenomenon. And give the comparative advantages of a few formulas about the radiowave propagation. Second, Analyzing the theory of two dimensional standard parabolic equation, three dimensional standard parabolic equation, vector parabolic equation, Scalar parabolic equation, the expansion of pseudo differential operator is introduced. The accuracy was further improved. Third, we study about how to improve the accuracy of calculating the field energy. For the sake of computing the 3DPE quickly, a highly efficient SSFT algorithm is proposed which is so called approach of decomposed the field into odd and even parts. Numerical solution Split Step Fourier Transform is introduced, it can deal with the numerical solution very quickly and more accuracy, three dimensional parabolic equation model with wide angle is constructed by using the electromagnetic potential function. Comparing it with the earlier others which expressed by an arbitrary field component, the PE model in this paper is not only simple on the form but also efficient on solution. Fourth, the error of PE is analyzed and it can be dealt by putting forward method, introduce the method of sub long to replace the irregular path to reduce the error. we can get the initial fields on the base of antenna directional map, new 2D and 3D absorbing boundary conditions are analyzed and deduced, it is precise than the traditional method. They are dealt with infinite space electromagnetic radiowave propagation problems. Fifth, Analysis parabolic equations propagation characteristics in general medium, in order to deal with different polarize situation at the impedance boundary conditions in media. Sixth, comparing several irregular terrain models, for the present the most precise one is chosen. It simulates the familiar terrain and environments in the mobile communication, for example, ground, sea, mountains and several building, and some application about the loss of radiowave propagation problems in practice. For the case of a single building distributing on flat ground, different 3DPE model dealing with the buildings' vertical boundary incidence are brought forward. For the condition of vertical surfaces under methods of the different wave incidence, an approach of forward difference combining the Fourier transform is proposed. The results of this model are very accurate. In the end, the interface problems of software programmed in Matlab language, under the platform of Matlab have also been discussed. Using the tool of Matlab, It is useful math compute software, to design parameter input interface, making operation easier, the interface is more reasonable. We can set some different environmental parameters, and it can calculate more easily and output the result of the calculation and drawing graphics, very suitable for theoretical simulation.