The Study Of Over-horizon-transmission Characteristics Of Electromagnetic Waves In The Oceanic Waveguide Duct

The signal can not be spread according to the normal path because of waveguide structure in the air so that it will lead to the sea communication interrupt and communication quality decline. In addition, it will also cause the deterioration of error and performance when peolpe search for the radio target. Considering the over-the-horizon propagation characteristics of the signal in ocean waveguide in In the modern war, communication system and the electronic warfare ability will directly affect the merits of the tide of war. So the investment is necessary and important in this field.Methods of atmospheric duct communication mainly are ray tracing and PE (parabolic) analysis. This paper is to study the tracking of multipath transmission using the ray theory. I use PE method to study the electric field distribution and loss in the waveguide.This paper gives the wave attenuation model by simulation in different sea conditions. This paper analyses in detail the influence of marine environment on the transmission signal within the waveguide. I use the ray tracing to explore the multipath performance and distribution in the evaporation waveguide. I obtain the multipath time delay of the signal100km far from the start point is between10-9and10-7seconds by simulation. Given the reference model of angles of arrival and arrived heights distribution.Through the PE approximation and Fouerier method, I get the air space field and loss distribution in the space of the duct. The description results for different frequency electromagnetic wave propagation characteristics by PE analysis are discussed. We obtain that it is not suitable for the low-frequency radio waves propagation through simulation. The relationship of field distribution and waveguide thickness and strength is discussed. We compare attenuation rule of the different spectral wave in the waveguide in the paper. I study properties of remote communication in the waveguide and prove that propagation loss rate in the waveguide is less than in the normal air in the transmission far10-20kilometers from the transmission point. With the increasing of the distance, energy consumption fades slowly. Cosequently, duct communication strongly supports the ultra long distance communication. At last, the different reasons for loss are discussed in different methods. The advantages and disadvantages of each method are compared and analysised. The innovations of this paper are:the flat earth coordinate is creative used in the waveguide, simulation and analyze on the multipath arrival angle, delay spread, reach the height and amplitude, establishing multi-path model. In addition, in the fourth chapter, the initial field was deduced and setting. in the fifth chapter, I explore the adaptability of PE method on different frequency and the long horizon communication problem.