The Study Of Software Used To Predict The Electromagnetic Environment Near Communication Base Stations

With the rapid development of the mobile communication technology and the continuous growth of the city people and the individual needs of the wireless communication business, communication base stations are springing up all over the place. Lots of electromagnetic wave from the communication base stations, radio and television transmission system and the radar system is radiating to the space. If the considerable sum of electromagnetic wave is not controlled, it will cause serious pollution. This pollution will interfere with the electronic equipment, so that it will affect the normal work and bring about disease to people. Therefore, according to relevant provisions of our country, we should assess the effects to the environment of the communication base stations before it is established. And this determines the importance of radio wave propagation prediction.At present we use theoretical formulas according to the'Guideline on Management of Radioactive Environmental protection Electromagnetic Radiation Monitoring Instruments and Methods HJ/T 10.2-1996'to assess the effect of the space electromagnetic wave coming from mobile communication base stations, AM radio, short wave radio, FM radio, microwave transmission, TV and other electromagnetic radiations. In these formulas, first, we don't consider the effect of the terrain and the features of the earth around the electromagnetic radiations, such as the distribution of the buildings and etc, and we always assume that the transmitting antenna is sited on the flat and broad ground. Second, we don't distinguish the differences between the methods used to calculate the field close to the emitter and far from it. So there is great deviation compared with the measured value using these theoretical formulas to calculate the field around the emitter. For example, there is hundreds of times of deviation between the value calculated with the theoretical formulas and the actual value in estimating the effect of the electromagnetic wave from AM radio tower to the surrounding area. So we use the ray tracing algorithm in this article to accurately predict the field around the electromagnetic wave emitter.Firstly, in this article, we introduce the theory of the ray tracing algorithm, compare the forward ray tracing algorithm with the reverse algorithm, point out the different occasions they suitable for, and then illustrate the reason why we use the reverse algorithm in this article. The ray propagation mainly includes the direct propagation, the reflection, and the diffraction. The study on the ray propagation is always based on certain propagation environment. Secondly, we give the method how to establish the three-dimensional model. This model is suitable for establishing models of kinds of residential environment. Thirdly, we focus on introducing the efficient 3D path searching for the inverse ray-tracing method and the different formulas for calculating the electric field strength in the direct propagation, the reflection, and the diffraction, and then we development the electromagnetic environment prediction software with the VS 2008 platform. At last, we give the calculated value using the electromagnetic environment prediction software for a certain urban area, and compare it with the measurements. We can find the effectiveness of the 3D path searching for the inverse ray-tracing method and the correctness of the electromagnetic environment prediction software by comparing the results.