共查询到19条相似文献,搜索用时 609 毫秒
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杨臻颖 《太赫兹科学与电子信息学报》2006,4(3):175-180
TF/SF(Total Field/Scattered Field)法是FDTD(Finite-Difference Time—Domain)数值算法中引入平面波源的有效方法之一。本文对TF/SF法中的一维辅助渡源法进行改进,首先推导出三维FDTD网格内的电磁波传播群速和相速的近似解析解。为预测离散网格内电磁波传播提供理论基础;然后以此为依据,提出对一维辅助波源的时域群速补偿法。经过实际三维FDTD问题的数值模拟,证实了本文方法在保持一维辅助波源法高效简洁的同时,进一步减少了泄露误差,给FDTD计算散射问题提供了有力工具。 相似文献
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提出了一种基于周期结构split-field FDTD法的近埋地无限长散射体二维算法.该方法根据散射体轴向均匀性将三维split-field FDTD法转化为二维算法,减少了内存和计算量,可分析斜入射脉冲波照射下近地、埋地无限长散射体散射问题.为了进一步减小计算量,连接边界上的入射波(地上为原始入射波和反射波的叠加,地下为透射波)采用一维FDTD法引入.吸收边界采用了UPML匹配层,导出了适用于split-field FDTD算法与有耗介质匹配的UPML方程.通过数值算例,验证了此二维算法应用于近埋地无限长散射体问题的有效性和实用性. 相似文献
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应用分裂平面波时域有限差分(Splitting Plane wave Finite Difference Time Domain,SP-FDTD)方法到三维时域有限差分(Finite Difference Time Domain,DFDTD)中引入高效平面波源.该方法基于分裂场思想,在一维FDTD上构造了新的迭代公式,使得一维FDTD和三维FDTD离散网格之间的数值相速度一致,消除了由于相速不一致而在总场区引起的泄漏误差以及插值带来的数值误差.通过数值算例验证了SP-FDTD方法对不同波源在任意角度(斜入射)下的平面波入射都是有效的,且泄露误差均在-300dB水平. 相似文献
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设计了一种新型一维光子晶体慢光波导结构。在常规波导一侧进行了特殊的设计,使波导具有周期性结构,从而具有特殊的色散关系,获得慢光效应。基于麦克斯韦方程利用平面波展开法对光子晶体慢光波导的色散关系进行了分析,获得了波导模以及相应的慢光频率。并利用时域有限差分法(FDTD)对脉冲在波导的传播进行了时域上的模拟,对慢光效应进行验证。 相似文献
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首先用平面波展开法(PWM)计算了二维光子晶体的能带结构,然后提出了适合THz 波传输的光子晶体波导模型,并采用时域有限差分法(FDTD)研究了THz波在这种波导中的传输特性.在波导的输入输出口采样场值经过傅立叶变换以后进行比较,结果很合理.分析结果表明,位于光子晶体禁带内的THz波在这种波导中的传输是几乎没有损耗的,这为开发性能优良的THz 器件提供了理论依据. 相似文献
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用时域有限差分法(FDTD)分析了二维光子晶体的传输特性,研究了纯平面波源、高斯波源对传输特性的影响,指出在同一种激励源情况,二维光子晶体的传输特性与其入射角有关。 相似文献
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Joo Hwa Lee Dikshitulu K. Kalluri Gary C. Nigg 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(8):1223-1253
Finite-Difference Time-Domain (FDTD) algorithms are applied to study the transformation of a pre-existing electromagnetic plane wave by prescribed time variation of a cold magnetoplasma with a magnetic field along the propagation direction. A one-dimensional FDTD code is used to verify the results obtained earlier using analytical approximations based on (a) WKB method for slow switching of the plasma medium and (b) Green's function technique for rapid switching of the plasma medium. A novel successive reduction method has been developed and applied to obtain the amplitudes and the frequencies of the new modes generated by the switching of the medium. 相似文献
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一种新的FDTD入射场设置方法 总被引:11,自引:1,他引:10
本文提出了一种新的入射场设置方法.采用一维FDTD算法来模拟入射波.所得结果与通常的入射场解析表达式的结果比较表明,采用一维FDTD算法引入的入射波在总场区分布均匀,在散射场区泄漏小. 相似文献
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用FDTD方法求解电磁散射问题中,入射波的设置起着关键性作用。本文从FDTD零场初始条件出发,导出了入射波解析设置时的约束条件,该约束条件表明,在FDTD总场边界上要求入射波逐点延时设置,通过与自由空间及半空间散射数值例子对比,验证了该约束条件下入射波解析设置方法的正确性。 相似文献
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Spectral FDTD: a novel technique for the analysis of oblique incident plane wave on periodic structures 总被引:1,自引:0,他引:1
This paper introduces a new technique which calculates the reflection coefficient for the plane wave incident on planar periodic structures. The method referred to as spectral finite-difference time-domain (SFDTD) replaces the conventional single-angle incident wave, with a constant transverse wavenumber (CTW) wave. Because the transverse wavenumbers are constant, the fields have no delay in the transverse plane (x-y plane), and PBC (periodic boundary condition) can be directly implemented in the time domain for both oblique and normal incident waves. The stability criterion for this new FDTD technique is angle-independent and therefore this method works well for incident angles close to grazing (/spl theta/=90/spl deg/) as well as normal incident (/spl theta/=0/spl deg/). This shows the efficiency of the method compared to other available FDTD techniques for the same purpose that force a more restricted stability criterion as angles turns to grazing. The validity of this method is verified by comparing the reflection coefficient calculated by this method with the analytical results of a grounded slab. The results of this technique are also compared with method of moments for a periodic array of metallic patches and a good agreement is observed. A periodic array of metallic patches above a PEC plate is analyzed and the reflection coefficient is calculated over a wide frequency band for angles varying from 0/spl deg/ to close to 90/spl deg/. 相似文献
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R. Sauleau Ph. Coquet J.-P. Daniel 《Journal of Infrared, Millimeter and Terahertz Waves》2002,23(3):475-498
Accuracy of equivalent circuit models of periodic grids is investigated in amplitude and phase in the visible region. The grids studied here are one-dimensional (1D) and two-dimensional (2D) inductive thin metal meshes. They are located in free space and are illuminated by a plane wave under normal incidence. The range of validity and the accuracy of conventional circuit models are defined by comparison with rigorous results obtained with the Finite-Difference Time-Domain (FDTD) method. In particular, it is shown that electrical models of 1D grids are accurate, whereas equivalent circuits of 2D grids should be used very cautiously. Then, a new formulation is proposed to overcome this major drawback. In the non-diffraction region, the agreement between our model and the FDTD results is within 2% for the power reflectivity and 1° for the phase over a very wide range of strip widths. 相似文献
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Shaobin Liu Jinjun Mo Naichang Yuan 《Journal of Infrared, Millimeter and Terahertz Waves》2002,23(8):1179-1191
A finite-difference time-domain (FDTD) algorithm is applied to study the electromagnetic reflection of conduction plane covered with inhomogeneous, collision, warm, time-varying plasma. The collision frequency of plasma is a function of electron density and plasma temperature. Under the one-dimensional case, transient electromagnetic propagation through various plasmas have been obtained, and the reflection coefficient of EM wave through inhomogeneous time-varying plasma (ITVP), homogeneous time-varying plasma (HTVP) and inhomogeneous plasma (IP) are calculated under different conditions. The results illustrate that a plasma cloaking system can successfully absorb the incident EM wave. 相似文献
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We previously introduced high-accuracy finite-difference time-domain (FDTD) algorithms based on nonstandard finite differences (NSFD) to solve the nonabsorbing wave equation and the nonconducting Maxwell equations. We now extend our methodology to the absorbing wave equation and the conducting Maxwell equations. We first derive an exact NSFD model of the one-dimensional wave equation, and extend it to construct high-accuracy FDTD algorithms to solve the absorbing wave equation, and the conducting Maxwell's Equations in two and three dimensions. For grid spacing h, and wavelength /spl lambda/, the NSFD solution error is /spl epsiv//spl sim/(h//spl lambda/)/sup 6/ compared with (h//spl lambda/)/sup 2/ for ordinary FDTD algorithms using second-order central finite-differences. This high accuracy is achieved not by using higher-order finite differences but by exploiting the analytical properties of the decaying-harmonic solution basis functions. Besides higher accuracy, in the NSFD algorithms the maximum time step can be somewhat longer than for the ordinary second-order FDTD algorithms. 相似文献