The Research Of Parabolic Equation In The Troposphere

The duct which happens in the troposphere has great effects on the electromagnetic wave propagating. It can make the wave propagate further with less energy loss, but on the other side, it forms the radar holes in the vicinity. Because of radio wave propagating along the ducts with enhanced fields on the order of the free-space field, the problems of the co-channel interference are more complicate for communication systems with the results of intersystem interference and the formation of other system, and for surveillance system such as radar system. The problems can be radar holes or the extensions of detect range. So in present days, when the wireless technique has been wildly used, the researches on the characteristics of tropospheric ducts environment, propagation and its applications are very important.Tropospheric duct propagations has become a very complicate mufti-discipline problems at present, and be one of the tough and hot issues in the field of tropospheric propagation. In china, the research has been studied for only a few years, we also focus on the forecasting of duct and electromagnetic filed distribution in the troposphere.For the two aspects, firstly, the paper try to introduce the MM5 mesoscale prediction system which used well in weather report into electromagnetic environment of atmosphere researching field, in order to calculate refractive-index, and analyze the results. It is concluded that we can't direct use the MM5 system into our research. It has no sufficient sensitive mechanism, especially for the ducts phenomena. That may be the problem of internal computer system or approxmation degree. Secondly we give a basic view of the methods of calculating the field in the troposphere, make a detail deduce of the parabolic equation and introduce the earth flatting transformation. During modeling, we focus on the problem of absorption layer and initial field, and show the effect of layers with different heights. Then verify the validity of the theoretical model by simulating a plane wave in vacuum in non-earth flatting and earth flatting coordinates. After modeling, we simulate the attribution of the field in the troposphere, and analyze the pass loss of electromagnetic wave launch by Sinclair antenna in various ducts in the troposphere in the earth flattening coordinate. Then we compare the measured date with the calculating results, and the obsolute error of which is 5.93 dB on everage, 14.36 dB on max. The results show the effectivity of the parabolic method in calculating the pass loss of electromagnetic wave propergating in the troposphere near sea surface. At last, we discus the bright propectivity of the parabolic method.