發(fā)布時間：2018-05-24 03:52

  本文選題：拋物線方程 + 電波傳播　； 參考：《南京郵電大學(xué)》2017年碩士論文

【摘要】：拋物方程(Parabolic Equation,PE)法的計算公式不僅可以描述不規(guī)則的地形結(jié)構(gòu)、反映不均勻大氣的媒質(zhì)特性給電波傳播帶來的影響,并且該方法具有網(wǎng)格步長不依賴于波長的優(yōu)點,計算效率高。本文在基于二維拋物線方程(Two-Dimensional Parabolic Equation,2DPE)的研究基礎(chǔ)上提出了準三維拋物線方程(Quasi-Three-Dimensional Parabolic Equation,Quasi-3DPE)法來預(yù)測三維空間中電波傳播特性。首先,介紹了直角坐標系下二維格式。通過四種方法對偽微分算子做近似處理,選擇傳播仰角達30°的Feit-Flect法近似處理的PE。對該算法在求解過程中需考慮的邊界條件和初始條件給出了理論知識和計算的實例。其次,建立地形遮蔽模型來處理不規(guī)則地形的邊界,在二維空間用分步傅里葉拋物線方程(Split-Step Fourier Transforms,SSFT)法計算常見地形上的電波傳播問題,來預(yù)測遠距離不規(guī)則地形的電波傳播特性。計算結(jié)果正確地驗證了電波在不規(guī)則地形上的傳播特性。再次,在SSFT法預(yù)測二維空間電波傳播特性的基礎(chǔ)上提出了準三維法來預(yù)測三維空間電波傳播特性。以圓錐幾何體為例,該方法從視圖的角度,將圓錐視為兩個二維圖形,即三角形(垂直面)和圓形(發(fā)射源高度處的水平面),然后分別計算這兩個面上的電波傳播特性。在同一傳播距離、同一高度處將兩個平面上的場值相加,再計算相應(yīng)的傳播因子,即為圓錐的準三維結(jié)果。最后,研究了電波在對流層的復(fù)雜大氣結(jié)構(gòu)條件下的電波傳播特性。結(jié)合PE法,對復(fù)雜的大氣結(jié)構(gòu)進行處理,并通過實例的計算結(jié)果驗證理論的正確性。
[Abstract]:The parabolic equation (PE) method can not only describe the irregular topographic structure, but also reflect the influence of the medium characteristics of the inhomogeneous atmosphere on the radio wave propagation, and the method has the advantage that the grid step size is independent of the wavelength, and the calculation efficiency is high. In this paper, a quasi-three-dimensional parabola equation Quasi-Three-Dimensional Parabolic EquationQuasi-3DPE-based method is proposed to predict the propagation characteristics of radio waves in three-dimensional space based on the study of Two-dimensional Parabolic Equationation2DPE. Firstly, the two-dimensional scheme in right-angle coordinate system is introduced. The pseudo-differential operator is approximated by four methods, and the Feit-Flect method with propagation elevation of 30 擄is selected. The theoretical knowledge and calculation examples are given for the boundary conditions and initial conditions that need to be considered in the solution of the algorithm. Secondly, the terrain shading model is established to deal with the boundary of irregular terrain, and the propagation of radio waves on common terrain is calculated by using the split-step Fourier parabola equation in two-dimensional space to predict the propagation characteristics of radio waves in long distance irregular terrain. The numerical results verify the propagation characteristics of radio waves on irregular terrain. Thirdly, based on the prediction of the propagation characteristics of two-dimensional space radio waves by SSFT method, a quasi-three-dimensional method is proposed to predict the propagation characteristics of three-dimensional space radio waves. Taking the conical geometry as an example, the cone is regarded as two two-dimensional figures from the view angle, that is, the triangle (vertical plane) and the circular (horizontal plane at the height of the source), and then the propagation characteristics of the radio waves on these two planes are calculated respectively. At the same propagation distance and at the same height, the field values on the two planes are added together, and the corresponding propagation factors are calculated, that is, the quasi-three-dimensional results of the cone. Finally, the propagation characteristics of radio waves under the complex atmospheric structure in the troposphere are studied. The complex atmospheric structure is treated with PE method, and the correctness of the theory is verified by the calculation results of an example.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN011

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本文編號：1927585