Research On The Navigation Station Electromagnetic Signal Prediction Model In The Complex Terrain

Navigation station is of great importance in giving position information to aircraft while it flies, it guides the airplane in bad weather condition and complicated terrain conditions. At present, the increasingly flights demand a more stringent requirements toward electromagnetic environment. And the geographical environments around airports also become more complicated, it affects the spread of electromagnetic signals. In terms of all these conditions, to determine the real distribution of electromagnetic signals in actual terrain environment is very important. This article studies the electromagnetic signal range of the common navigation stations, as to NDB VOR and DME, in airport terminal area.This article researches on the antenna type and basic parameter of each beacon primarily. Then it conducts3-D modeling of electromagnetic signals of common beacon antenna in free space with the help of antenna theory and simulation method, thus to get the space electromagnetic data of each electromagnetic signal model. Considering the terrain environment, earth curvature, atmosphere refraction and using wave propagation theory to calculate the distribution and decay, this article revises the space electromagnetic data. When calculating the terrain effect on electromagnetic signal, it proposed’ boundary fuzzy approximation algorithm’ to simplify the terrain profile to improve efficiency. The algorithm effectively solves the problem of complex computation while it calculates the electromagnetic signal in complex terrain environment and ensures the accuracy of computation.On the basis, the article combined the free space electromagnetic signal with digital terrain model. And it uses boundary fuzzy approximation algorithm to calculate DEM data. Then it issued the detailed algorithm of terrain-effected electromagnetic signal based on wave propagation theory. The detailed algorithm is to calculate the crossing situation of terrain and different elevation signal rays in the profile at certain step length primarily, and applied the profile algorithm at certain step length in azimuth, therefore it can get the whole3-D electromagnetic signal space distribution map in complex terrain environment.