加热电离层中的电波传播特性研究

发布时间：2018-06-26 18:27

本文选题：电离层加热 + 射线追踪　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：随着科学技术的不断发展,电离层通信也渐渐的成为了人类生活的一部分,如广播、电视、无线通信、全球定位系统(GPS)的定位和导航等人类活动与电波在电离层中的传播息息相关。近年来,自从人们发现人工加热电离层可以明显干预电离层中电磁波的传播特性,该方向的研究就一直备受国内外学者关注。本文基于电离层加热模型与射线追踪方法,对加热电离层中电波的传播特性展开了系统的研究。主要工作如下:1.简要的阐述了人工加热电离层和在加热电离层中电波传播的研究背景和意义。探讨了电离层加热在民用及军事技术应用上的重要性。2.从电离层欧姆加热理论出发,根据电子密度变化的连续性方程、粒子的动量方程和能量守恒方程,介绍了电离层加热的数值仿真模型。并以国际电离层参考模型IRI-2012和中性大气模型MSIS-90为背景,在不同的加热时间和不同的加热功率的条件下,对电离层加热进行了数值仿真。从而确定这加热时间和加热功率对加热电离层的电子密度、电子温度扰动的影响。3.基于射线追踪的Haselgrove方程,在已知背景电离层电子密度梯度的条件下,利用龙格库塔数值计算方法,介绍了在电离层中电波传播的变步长射线追踪模型。根据该射线追踪模型,绘制了电波传播轨迹。并且对电波在常规的、含有Es层的,和含有加热F层的电离层中传播的射线追踪进行了仿真和分析。研究了Es层和加热F层的存在对电磁波在电离层传播的影响。4.介绍了在电离层中电波可能存在的传播模式,从理论上对多径效应进行了分析。其次,给出了电波在电离层传播过程中的传输损耗、吸收损耗和反射损耗的数学表达式并进行了理论分析。接下来,分析研究了电离层竖直方向上的运动,不规则体加热F层的竖直方向上的运动,电离层内电子密度的变化,以及地磁场随时间的变化对多普勒频移的影响。最后通过计算机仿真研究了不同发射仰角和不同发射频率的电波在电离层中的回波效应。5.首先,对电波在电离层不规则体加热F层的散射理论进行了介绍,基于该理论,对电波在电离层不规则体F层中的散射进行了仿真,为定量分析电波在不规则体散射的雷达散射截面RCS提供了理论指导。
[Abstract]:With the development of science and technology, ionospheric communication has gradually become a part of human life, such as radio, television, wireless communications, Human activities such as positioning and navigation of global positioning system (GPS) are closely related to the propagation of radio waves in the ionosphere. In recent years, since it has been found that artificial heating of the ionosphere can significantly interfere with the propagation characteristics of electromagnetic waves in the ionosphere, the research in this direction has been concerned by domestic and foreign scholars. Based on the ionospheric heating model and the ray tracing method, the propagation characteristics of the electric waves in the heated ionosphere are studied systematically in this paper. The main work is as follows: 1. The research background and significance of artificial heating ionosphere and electric wave propagation in heated ionosphere are briefly described. The importance of ionospheric heating in civilian and military applications is discussed. Based on the theory of ionospheric ohmic heating the numerical simulation model of ionospheric heating is introduced according to the continuity equation of electron density the momentum equation of particles and the energy conservation equation. Based on the international ionospheric reference model IRI-2012 and the neutral atmospheric model MSIS-90, the ionospheric heating is numerically simulated under different heating time and different heating power. The effects of heating time and heating power on the electron density and electron temperature disturbance of the heating ionosphere are determined. Based on the Haselgrove equation of ray tracing, the variable step size ray tracing model of radio wave propagation in the ionosphere is introduced by using the Runge-Kutta numerical method under the condition of known background electron density gradient. According to the ray tracing model, the track of radio wave propagation is plotted. The ray tracing in conventional, es and heated F ionosphere is simulated and analyzed. The influence of the existence of es layer and heated F layer on the propagation of electromagnetic wave in the ionosphere is studied. The possible propagation modes of radio waves in the ionosphere are introduced, and the multipath effect is analyzed theoretically. Secondly, the mathematical expressions of transmission loss, absorption loss and reflection loss during ionospheric propagation are given and analyzed theoretically. Then, the motion of the ionospheric vertical direction, the vertical motion of the irregularly heated F layer, the variation of the electron density in the ionosphere and the influence of the geomagnetic field with time on the Doppler frequency shift are analyzed. Finally, the echo effect of radio waves with different elevation angles and different emission frequencies in the ionosphere is studied by computer simulation. First of all, the scattering theory of electric wave in F layer heated by irregularly ionospheric body is introduced. Based on this theory, the scattering of radio wave in F layer of irregularly ionospheric body is simulated. It provides theoretical guidance for quantitative analysis of RCS of radio wave scattering in irregular bodies.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN011

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