共查询到18条相似文献,搜索用时 109 毫秒
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由于电磁波在穿越不同介质时会出现折射现象,因此在机载条件下对地下目标成像时,电磁波信号从机载雷达到达地下目标的整个路径不是直线而是折线,此时再利用常规的自由空间中合成孔径成像方法已经不能对目标进行良好成像.基于电磁波的传播规律和地层有耗媒质的特性,文章提出了电磁波传输的三层空间模型,并将其应用到机载条件下的地下目标成像,通过仿真比较,可以明显看出,使用三层空间模型后对地下目标成像效果的改善,验证了三空间模型适用于机载条件下对分层土壤中的地下目标成像. 相似文献
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介绍了一种新型的利用甚低频电磁波进行水雷遥控的方案;利用甚低频的衰减特性,计算出在距发射点约400km处的辐射电场的场强,分析了在水下15m处与30m处的近似场强,根据得到的数据得出了甚低频遥控水雷设计的可行性;在此基础上,进一步论述了用FSK进行数字调制的系统设计方案,详细描述了遥控发射机与接收机的设计方法,水雷的分区编解码原理以及发射与接收天线的设计。 相似文献
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为了研究带有传送带的矩形巷道电磁波传播规律,提出一种基于电磁波传播理论和多波模理论的等效分析法,旨在降低研究电磁波传播计算的复杂性.利用计算机对有传送带的矩形巷道中电磁波传播规律进行仿真,将等效分析法方案计算出的仿真数据分别与矿井巷道中实际测量的3组数据进行对比分析.实验结果表明:等效分析法可以近似分析带有传送带的矩形巷道中的电磁波传播的情况,等高方案在30 m范围内的电磁波衰减规律更加符合实测数据.因此该方法可以应用在大型障碍物巷道中研究电磁波传播影响. 相似文献
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I. B. Bakholdin A. V. Berezin A. A. Kryukov M. B. Markov B. D. Plyushchenkov D. N. Sadovnichii 《Mathematical Models and Computer Simulations》2017,9(2):190-200
A technique for the numerical simulation of electromagnetic wave propagation in materials with permittivity depending on the frequency is presented. The technique is based on numerical solutions of Maxwell equations with additional integral components in the bias current density. The technique to calculate the bias current density in dispersive media is represented and the corresponding modification of finite-difference scheme for Maxwell equations developed earlier is carried out. The electromagnetic pulse propagation in solid-fuel power systems is calculated. 相似文献
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在线监测电缆的局部放电情况是及时发现故障隐患、预测运行寿命及保障电网安全可靠运行的重要手段.简要介绍了超高频传感器的研究方法和原理,并分别对超高频电磁耦合传感器和超高频电容传感器做了分析.根据电磁波在同轴波导中的传播理论,运用高频结构仿真器 (HFSS) 软件对 110 kV 电缆中间接头进行仿真,通过仿真可以得出:局... 相似文献
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Electromagnetic wave propagation in turbulent plasma media during reentry is being investigated. Emphasis is placed on the effects of electron density fluctuations on electromagnetic wave propagation. The objective of this paper is to specify the source of noise in electromagnetic signal reception due to turbulence in the flow about a high velocity flight vehicle. A review of existing ground and flight test data is conducted, including electron density fluctuation measurements. Analytical algorithms deduced from first principles are being developed and validated with experimental measurements. A Navier-Stokes model, three-dimensional parabolized Navier-Stokes, and a coupled boundary-layer and inviscid flow codes are used to estimate the mean and variance of the electron density on the frustum and at the vehicle’s base region. Analytical and numerical solutions solving Maxwell’s equations and a commercial off the shelf code are used to estimate the phenomena of electromagnetic wave propagation in inhomogeneous plasma media. Results include the estimation of signal attenuation and phase shift induced by the mean electron density and by electron density fluctuations in the flowfield. Comparisons are made between the predictions and available data. 相似文献
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Based on the invariable displacement current of anisotropic media, a theoretical model for electromagnetic reconstructing anisotropic media and a basic method for selecting electromagnetic field are proposed. Taking the gypsum crystal as an example, the analytical solution of bi‐axial medium scattering is presented by using the spherical vector wave function of electromagnetic field. The electromagnetic wave scattering of the anisotropic medium spheres are simulated in radiation of electromagnetic waves of different frequency. The electromagnetic analysis of the simulation results shows that the electromagnetic mechanism is consistent with the results of relevant literature. When the anisotropic medium degenerates to the isotropic medium, the results obtained by the model are completely consistent with those obtained by Mie theory. 相似文献
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海中低频水平磁偶极子在空气中产生的电磁场 总被引:1,自引:0,他引:1
采用电磁波进行跨海水-空气界面通讯时,合理的天线形式是影响通信性能的重要因素之一。为了研究环形天线在跨海水-空气界面通讯中的特点,根据磁偶极子性能,考虑海底-海水-空气三层各向同性的分层模型,推导出置于海水中的水平磁偶极子空气中激发的电磁场分量的解析表达式。进一步采用数值方法,计算了顶层空气中电磁场的分布和传播规律。结果表明,海水中的低频水平磁偶极子在空气中激发的电磁场的各个分量在垂直面内有不同的方向性,且在距发射源较近时有快速的衰减,随着距离增大,衰减逐渐减缓,但在一定高度和水平范围内有可测量的量级,说明环形天线在此类型通讯中是可行的。 相似文献
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