Research On Radio Wave Propagation In Complex Ocean Environment Based On Two-way Parabolic Equation

With the development of radio technology and the in-depth study of electromagnetic research,wireless communication system has been widely used in various fields of human life,such as satellite communication,GPS positioning,radar warning,remote sensing and telemetry system,etc..The prediction of radio wave propagation in complex environment has gradually become an important research topic.Since the ocean is large in area and abundant in resources,it is very important for t he national economic development and strategic deployment to study the radio waves propagation in the marine environment.The parabolic equation method is a numerical solution for predicting the electromagnetic field propagation in the troposphere.It can handle irregular boundary conditions and atmospheric waveguide environment at the same time.The parabolic equation is widely used in the prediction of radio waves in various environments because its relatively simple calculation method.The traditional parabolic equation method is a two-dimensional one-way algorithm,which only considers the forward propagation of the radio wave and ignores the backward propagation.The error between the result and the true value is large.When there is an obstacle in the propagation process,the prediction result of the traditional parabolic equation method will produce a large error compared to the real value.Therefore,in this paper,the two-way parabolic equation is applied to solve the wave propagation characteristics in various complex marine environments.The complex marine environments include rough sea surface,atmospheric waveguide,island terrain and other factors.The two-way parabolic equation(2WPE)was solved by finite difference method,and the improved fractal model was applied to simulate rough sea surface to analyze the influence of the rough sea on the propagation of electric waves under wind.Finally,we study the two-way three-dimensional parabolic equation and its alternative direction implicit(ADI)solution.Firstly,from the Maxwell equations,through a series of deformations and simplifications,the elliptic wave method is transformed into a parabolic equation.In the forward and backward parabolic equations,the finite difference method is used to solve them.The process of solving the two-way parabolic equation by the finite difference method is deduced in detail.We introduced the processing method of irregular terrain and impedance boundary conditions in the calculation process of forward and backward parabolic equations.Secondly,a new improved fractal model is used to simulate the rough sea surface under different wind speed conditions,and the propagation of radio waves in this model is calculated.In the process of forward and backward propagation of radio waves,the improved fractal model is used to simulate the rough sea surface profile,and the propagation characteristics of radio waves in this model under different wind speed conditions are analyzed.Under the same conditions,the two-way propagation factors of radio waves simulated by the improved fractal model and the classic Miller Brown model are compared to verify the effectiveness of the improved fractal model in the two-way propagation of radio waves.Finally,the propagation factors of two-way radio waves in the improved fractal model are calculated by combining the model with the common types of atmospheric waveguides over the sea.Finally,the forward and backward propagation of electric wave in three-dimensional environment is studied.First,according to the crank Nicolson finite difference method,the difference scheme of the three-dimensional parabolic equation is derived.The ADI method is proposed to solve the three-dimensional two-way parabolic equation for the first time,and the ADI solution formula of the three-dimensional forward and backward parabolic equation is derived in detail.Finally,the two-way propagation characteristics of the three-dimensional environmental radio wave are solved by an example.