平行分层海域中电偶极子源的定位方法研究

针对平行分层海域中电偶极子源的定位问题,提出利用三个电场强度传感器同时确定场源位置、场源强度及分界面方位共9个参量的方法.首先借助镜像法及边界条件推导了三层平行分层海域中电偶极子源在海水中产生电场强度的矩阵表达式,引入场强传递矩阵,然后通过传递矩阵求逆的方法消除电偶极子源的偶极矩参数,得到以电偶极子源位置及分界面方位为未知量的非线性方程组,将待确定的9个未知参数减少为6个待拟合量,并通过拟合的方法得到电偶极子源位置和分界面方位的最优解.最后通过仿真算例检验所提方法的有效性.结果表明,该定位方法在一定条件下可以较精确地确定场源位置、分界面方位.该方法经适当完善还可以应用于鱼雷等水下航行器的制导过程.     

左手介质在增强电偶极子辐射功率上的应用

基于严格的电磁场理论,给出了左手介质壳包围电偶极子后的辐射场本征函数级数解.应用该级数解求解出该情况下的辐射功率,并与自由空间中电偶极子辐射场进行了比较,指出了左手介质在增强电偶极子辐射功率上的应用,并运用微波电路理论对该特性进行了分析验证.     

箔条偶极子的雷达截面积

本文介绍了由于平面电磁波激励在具有有限电导率偶极子上产生电流分布和积分差分方程，采用变分法求解该方程，得到了偶极子的微分散射截面和雷达截面积的计算表达式。实现了计算的微机程序化，计算了偶极了在不同的空间取向了随机分布状态下的雷达截面积。     

在三层介质中运动的时谐水平偶极子产生的电磁场

 为了使舰船轴频电磁场能被真正应用于新型水雷武器引信,本文求解了在三层介质中运动的时谐水平偶极子在固定场点产生的电磁场.求解过程分为两步,首先求解静止时谐偶极子在介质中的固定场点产生的电磁场,然后通过狭义相对论的洛仑兹变换,得到匀速运动的时谐电偶极子在固定场点产生的电磁场.以浅海中低速运动的极低频时谐水平偶极子为例,对其产生的电磁场进行了数值计算,并且通过对比分析不同条件下的计算结果得出了一些有价值的结论.最后通过将计算结果与试验数据的对比,验证了本文的实用性和正确性.     

共形偶极子天线阵的分析与计算

本文对与有限长空心圆柱筒共形的偶极子天线阵进行了分析与计算，采用矩量法（ＭＯＭ），并利用分块求逆求广义导纳矩阵。作为例子，求解了阵中偶极子的单元方向图和输入阻抗。     

基于RWG法分析考虑互耦的阵列方向特性

RWG(Rao-Wihon-Glisson)三角基函数为基础的矩量法是分析偶极子天线阵列的有效方法.通过求解阻抗矩阵和矩量方程,可分析天线互耦特性.偶极子模型法是将包含2个三角的RWG边元的表面电流分布用具有等效偶极子矩量的无穷小偶极子代替来求解天线辐射场.运用偶极子模型法替代传统的电场积分法来求解阵列方向图,对考虑互耦偶极子阵列的方向图进行了仿真,并对比分析了和理想情况下的差异.同通常的电场积分方程法相比,此方法具有计算简便,物理意义明确,可分析任意形状的天线等特点.     

半导体微腔中电偶极子的自发发射

由于反射电场的影响，电偶极子在微腔中的自发发射速度不同于自由空间中的自发发射速度。本文采用镜像法计算了理想平面微腔、金属平面镜组成的半导体微腔和由分布布喇格反射镜（DBR）作为谐振腔的垂直发射激光器（VCSEL）中电偶极子的自发发射速率。计算结果表明：由于微腔的调制作用，在某些情况下电偶极子自发发射速率增加，在一定腔长下电偶极子自发发射速度被抑制。     

填充电各向异性媒质的矩形波导的研究

导出了在直角坐标系中电各向异性媒质中的波动方程，并在单轴晶体填充的矩形波导中进行了求解，研究了场的特性，找出了一些规律性的结论。     

耗散介观电路的量子波函数和零点起伏

运用正则化变换结合路径积分方法，求解了有源介观耗散电路的量子波函数，并进一步研究了介观电路中电荷、电流的量子起伏．     

印刷偶极子的对数周期天线的分析

本文描述有关印刷偶极子对数周期天线的分析。在这篇分析中,应用平面条带偶极子边界条件在笛卡儿座标中求解赫兹电位波动方程。用这种模型,计算出各天线单元的输入电流、各天线单元上的电流分布和整个天线的辐射方向图。其计算结果与实验结果作了比较。     

The electromagnetic field of a vertical electric dipole over theEarth or sea

The analysis of King (1990) of the electromagnetic field of a vertical electric dipole over an imperfectly conducting half-space is applied to obtain the far field when the dipole is at a specified height d. The contributions by the space wave with its 1/r dependence and the lateral surface wave with its 1/r² dependence are separated and studied in detail when the dipole is over a wide range of media such as sea water, wet and dry Earth, lake water and dry sand. Graphs of the far-field patterns are shown     

Far-field radiated from a vertical magnetic dipole in the sea with a rough upper surface

The problem of communication in the sea has been considered as propagation of radio waves in a three-layered medium (air, sea, and ground). With the aid of the perturbation calculus, this paper analyzes the influence exerted onto the electromagnetic field of arrangements radiating a pure transverse electric field in the sea. The sea height varies continuously with the distance from the transmitting end due to sea waves. Knowledge of the solution for the case of uniform sea height is presumed. The problem of the transition conditions at the upper boundary of the sea is solved in the imaging space of a Hankel transformation. Its reversal produces an integral presentation of the interfering field, which was previously quite difficult to evaluate. In this study, closed-form expressions for the far-field of a vertical magnetic dipole embedded below the sea surface are obtained by using a new technique to evaluate this integral with the aid of the complex image theory. The results obtained are compared with those mentioned elsewhere.     

HF Radio Wave Transmission over Sea Ice And Remote Sensing Possibilities

Ground wave propagation is analyzed for a path where sea water is covered by a uniform layer of sea ice. The source is taken to be a vertical electric dipole on or above the ice layer. The solution indicates that a trapped surface wave is significant at short ranges while, at longer ranges, the usual ground wave modes are dominant. The resulting interference pattern may produce rapid variations of the field at intermediate ranges. These characteristics, as well as the height dependence of the observed field strength, are strongly dependent on the thickness of the ice layer.     

层流介质中曲面螺旋桨旋转对腐蚀静电场的影响

为了研究实际海水环境下螺旋桨转速及海水流速对舰船腐蚀静电场的影响,提出了一种层流介质条件下腐蚀静电场的求解方法.结合流体力学及电化学相关理论,建立层流状态下的曲面螺旋桨旋转模型,利用动量积分法和电化学方法分别求解层流介质下曲面桨叶表面的边界层厚度和极限腐蚀电流密度,基于该电流密度建立电偶极子模型对腐蚀静电场进行求解,并通过实验验证结论的正确性.结果表明：层流状态下,静电场的幅值大小随着螺旋桨转速及介质流速的增加而增加,在流速及转速较小时,理论数据与实验数据拟合程度较好.     

Accuracy of predicting the attenuation function with the use of impedance boundary conditions for a two-layer propagation path

An approximate value of the surface impedance for the electromagnetic field of a vertical electric dipole, is obtained. This field is observed over the surface of a homogeneous or two-layer structure and corresponds to the impedance of a plane vertically polarized electromagnetic mode sliding over the interface. The possibility of predicting the electromagnetic field at arbitrary values of relative complex permittivity of two-layer structures is confirmed, in particular, in the presence of forests and sea ice.     

Air to undersea communication with magnetic dipoles

Simplified expressions are derived for the electromagnetic fields produced by a vertical or horizontal magnetic dipole (loop antenna) located in air above the sea. The expressions hold over the quasi-near range in both media subject to certain mild restrictions. The solutions are obtained by first applying the boundary conditions to determine the magnetic Hertz potentialbar{pi}^{ast}in the form of Sommerfeld integrals, and then relating these to two auxiliary integralsU, Vand their derivatives, asymptotic series for which are obtained by extending the work of Baños and Wesley. The horizontal magnetic dipole (loop in the vertical plane) is found to be superior to the vertically-oriented dipole of the same size and excitation from the point of view of field strength induced in the sea at large distances from the source. A comparison with previously published results for the electric dipole shows the magnetic dipole to be better, provided the number of turns in the loop exceeds a certain minimum. An approximate analysis on the basis of equal powers also shows the magnetic dipole to be better except for points near the outer rim of the quasi-near range, where the two types of dipoles are equivalent.     

电偶极子和磁偶极子场分布相似性的一种解释

电偶极子电场与磁偶极子磁场具有相似的空间分布。然而,这种相似性并非显而易见：电偶极子由一对等量异号电荷组成,而磁偶极子则是一个电流回路。本文从矢量场边值问题的唯一性定理出发,得出了面散度源和面旋度源产生的矢量场分布的一种等价关系,进而对电偶极子电场与磁偶极子磁场空间分布的相似性进行了解释。     

海水包裹空心椭球体的低频散射场计算及分析

为了分析水下金属壳体目标的散射场,提出了一种基于移位算子时域有限差分方法的加速计算方法.利用该方法对海水、空气和金属三种媒质材料进行了建模,并计算了水下金属椭球状壳体目标低频散射场的空间分布和起伏海面对低频电磁波传播的影响.通过数值算例测试了所提方法的加速性能,可以得到接近线性的加速比和95%以上的加速效率.计算结果表明,海面会影响水下壳体目标散射场的空间分布,特别是对于电场的空间分布影响比较大,并且由于水下电导率的存在导致海面上方散射场的传播速度要比海面下方的快.     

海水中极低频水平电偶极子电磁场的解析解

将海水看作线性、均匀、各向同性的半无限大导体空间,利用汉克尔变换及开尔文函数的近似展开式,推导求得了极低频时谐水平电偶极子在海水中产生的电磁场的近似解析表达式.运用推导的解析表达式,可以计算海水中任意场点的电磁场值.     

Electromagnetic field of a horizontal electric dipole buried in a medium covering one-dimensionally anisotropic medium

The electromagnetic fields of a horizontal electric dipole buried in a medium covering one-dimensionally anisotropic medium are studied. There are three media, one-dimensionally anisotropic medium covered with a dielectric under the air. The electromagnetic field components are complex because of the multiple reflections from the up and down boundaries. The electromagnetic field components between air and one-dimensionally anisotropic medium are given, the trapped surface waves and lateral waves along the dielectric-anisotropic medium boundary are computed. The results have some practical applications in the communication in sea or lake above one-dimensionally anisotropic earth or sediments.