Research On Over-the-horizon Propagation On The Sea

The last hundred years after World War ?,with the emphasis on complex factors affecting marine rights and interests of all countries,the analysis of tropospheric scatter,ducting and other electromagnetic wave propagation has been of concern to all countries' engineer.It's generally believed that the transmission of electromagnetic waves at microwave frequencies and 2GHz bands above the ocean surface is more heavily dependent on the types of the waveguide layer.The transmission signal will be trapped by the ocean-atmosphere and the waveguide,spread in the atmosphere,and spread over the horizon while reducing its attenuation.In recent years,the experimental results show that the communication over the sea,400MHz UHF band electromagnetic wave nearby can achieve ultra-horizon communications with great probability.Therefore,we can extend the scope of the study over the horizon at sea broadband communications to a wider band.To satisfy the high rate point to point communication requirement of naval ship-ship and ship-shore,enhance the construction of naval communications,this paper focuses on the electromagnetic wave propagation models and communication channels on the sea over the horizon.The main work is as follows:First,a comprehensive analysis and study of various types of offshore surface atmospheric ducts show the spatial and temporal distribution.By using the parabolic equation model and the US Navy software AREPS for predicting the path loss of radar communication,we analyze the influence of the three atmospheric duct to the communication of electromagnetic waves on the sea over the horizon,have the simulated analysis for the path loss,figure out the CDF(cumulative distribution function)of different distance and different antenna height,and come to a conclusion of different atmospheric duct.It turns out that we design multi-band electromagnetic transmission systems in practice on the situation of coexistence of multiple mechanisms.Second,the model of small scale fading for electromagnetic wave propagation on the sea over the horizon is established by using the superposition method of sine wave and we conduct the experiment about its simulation and build the point-to-point communication system in practice.We choose the SC-FDE for the access of the system;choose the Turbo and QPSK for the channel code and modulation model;considering the small and large scale fading,finish the research of the transmission of electromagnetic waves on the sea over the horizon.The result shows that this system has a good performance on facing the additive noise and we can choose the electromagnetic wave of different bands for the communication on the sea over the horizon under different situations.The main contribution and innovations of the paper are as follows:this paper analyzes the classification of the atmospheric duct and properties of these atmospheric ducts;makes a study of various types of offshore surface atmospheric ducts of their spatial and temporal distribution near our country;simulates the computing method of path loss for the electromagnetic wave on the condition of atmospheric duct and compare it against AREPS;extends the frequency range of the electromagnetic wave that goes through the atmospheric duct and figure out the selection strategy under different situations;study the channel model and build the small scale fading model;under the condition of small scale fading model,design the simulation system,combine it with parabolic equation,using these systems make a research on the point-to-point communication on the sea over the horizon and draw a conclusion in the end.