共查询到17条相似文献,搜索用时 532 毫秒
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在用时域有限差分法(FDTD)分析色散媒质电磁问题过程中,采用无限冲激响应滤波器模拟媒质的色散特性,讨论了包括冲激响应不变法和双线性变换法等滤波器设计方法在这一新领域中的应用。改进的FDTD法利用成熟的数字信号处理技术分析处理了色散媒质瞬变电磁场问题,为数字信号处理技术在时域电磁场分析领域的应用提供了新的思路。为验证此方法的有效性和可靠性,分别用滤波器系统模拟了不同色散媒质。并在此基础上用FDTD对色散媒质电磁问题进行了分析计算,同时验证了结果。 相似文献
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提出了一种新的N阶色散媒质的时域分析方法,并将其表征为一组无限冲击响应滤波器,将色散媒质在FDTD中的表述问题转化为数字滤波器(IIR)的设计问题。改进FDTD能分析处理与频率有关的电磁场问题。为验证此方法的有效性和可靠性,用此方法计算了高斯平面波脉冲入射N阶色散媒质的情况,计算结果与解析值非常吻合。 相似文献
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N阶色散媒质的瞬态散射特性 总被引:3,自引:2,他引:1
本文提出了N阶色散媒质瞬态特性的时域分析方法,结合Z变换对常规的时域有限差分(FDTD)法进行了修正,改进后的FDTD法能分析和与频率有关的电磁场问题,具有方法简洁、易实现等优点。为验证此方法的有效性和可靠性,对N阶色散媒质的反向系数进行了分析与计算,并与已知的解析结果进行了比较,同时,采用此时域方法对N阶色散媒质和导体覆盖N阶色散媒质散射场进行了计算和分析。 相似文献
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基于交替方向隐式(ADI)技术的时域有限差分法(FDTD)是一种非条件稳定的计算方法,该方法的时间步长不受Courant稳定条件限制,而是由数值色散误差决定。与传统的FDTD相比, ADI-FDTD增大了时间步长, 从而缩短了总的计算时间。该文采用递归卷积(RC)方法导出了二维情况下色散媒质中ADI-FDTD的完全匹配层(PML)公式。应用推导公式计算了色散土壤中目标的散射,并与色散媒质中FDTD结果对比,在大量减少计算时间的情况下,两者结果符合较好。 相似文献
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为模拟一般Davidson-Cole色散媒质中的电波传播,本文提出了一种时域有限差分(FDTD)改进方案,改进之处体现在:(1)适用媒质从单极推广到多极情形;(2)适用媒质从无磁推广到有磁情形;(3)保留了色散模型公式的静态电导率项;(4)补充了三维问题算例.改进方案中,面临的主要困难是差分离散分数阶导数.首先,利用帕德(Padé)多项式近似媒质的介电常数;其次,通过傅里叶逆变换(IFT)导出了一组整数阶的辅助微分方程(ADEs),从而巧妙克服了该困难.几个算例的结果和分析,初步证实了改进方案的可行性和有效性. 相似文献
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引入一种新的数值计算方法 —辛算法求解Maxwell方程,即在时间上用不同阶数的辛差分格式离散,空间分别采用二阶及四阶精度的差分格式离散,建立了求解二维Maxwell方程的各阶辛算法,探讨了各阶辛算法的稳定性及数值色散性.通过理论上的分析及数值计算表明,在空间采用相同的二阶精度的中心差分离散格式时,一阶、二阶辛算法(T1S2、T2S2) 的稳定性及数值色散性与时域有限差分(FDTD)法一致,高阶辛算法的稳定性与FDTD法相当;四阶辛算法结合四阶精度的空间差分格式(T4S4) 较FDTD法具有更为优越的数值色散性.对二维TMz波的数值计算结果表明,高阶辛算法较FDTD法有着更大的计算优势. 相似文献
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Z-transform theory and the FDTD method 总被引:12,自引:0,他引:12
《Antennas and Propagation, IEEE Transactions on》1996,44(1):28-34
In implementing the finite-difference time-domain (FDTD) method on materials which are dispersive or nonlinear, the relationship between the flux density and the electric field can be the most complicated part of the problem. Because the FDTD method is a sampled time-domain method, this relationship can be can be looked upon as a digital filtering problem. The Z transform is typically used in digital filtering and signal processing problems. The paper illustrates the use of the Z transform in implementing the FDTD method where complicated dispersive or nonlinear materials are involved 相似文献
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The full-wave analysis of multiconductor transmission lines on an inhomogeneous medium is performed by using the two-dimensional finite-difference time-domain (FDTD) method. The FDTD data are analyzed by using signal-processing techniques. The use of high-resolution signal-processing techniques allows one to extract the dispersive characteristics and normal-mode parameters, which include decoupled modal impedances and current and voltage eigenvector matrices. A new algorithm for extracting frequency-dependent equivalent-circuit parameters is presented in this paper. Smaller CPU time and memory are required as compared to the three-dimensional FDTD case. Numerical results are presented to demonstrate the accuracy and efficiency of this method 相似文献
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DC power-bus design using FDTD modeling with dispersive media andsurface mount technology components
Xiaoning Ye Koledintseva M.Y. Min Li Drewniak J.L. 《Electromagnetic Compatibility, IEEE Transactions on》2001,43(4):579-587
DC power-bus modeling in high-speed digital design using the finite-difference time-domain (FDTD) method is demonstrated herein. The dispersive character of the dielectric layers used in printed circuit board substrates is taken into account in this study. In particular, FR-4 is considered. The complex permittivity of the dielectric is approximated by a Debye model. A wide-band frequency response (100 MHz-5 GHz) is obtained through a single FDTD simulation. Good agreement is achieved between the modeled and measured results for a typical dc power-bus structure with multiple surface mount technology (SMT) decoupling capacitors placed on the printed circuit board (PCB). The FDTD method is then applied to investigate some general approaches of power-bus noise decoupling 相似文献
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The finite-difference time-domain (FDTD) method has been widely used to simulate the electromagnetic wave propagation in biological tissues. The Cole-Cole model is a formulation which can describe many types of biological tissues accurately over a very wide frequency band. However, the implementation of the Cole-Cole model using the FDTD method is difficult because of the fractional order differentiators in the model. In this letter, a new FDTD formulation is presented for the modeling of electromagnetic wave propagation in dispersive biological tissues with the Cole-Cole model. The Z-transform is used to represent the frequency dependent dielectric properties. The fractional order differentiators in the Cole-Cole model is approximated by a polynomial. The coefficients of the polynomial are found using a least-squares fitting method 相似文献
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Dong Xiaoting Jiang Yansheng Wang Wenbing 《Microwave and Wireless Components Letters, IEEE》2001,11(6):267-269
The propagation of electromagnetic waves in a linear, dispersive Lorentz medium is calculated using the finite-difference time-domain (FDTD) method; their time-frequency (TF) characteristics are studied using the Gabor extension. Numerical results show that the TF spectrum gives a clear interpretation for transient evolution of ultra wideband pulse propagation through a Lorentz medium 相似文献
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Hongwei Yang R. S. Chen Yongchun Zhou 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(9):751-758
In this paper, a novel finite-difference time-domain (FDTD) method with recursive relationships among operators is developed for magnetized dispersive medium, named as the shift operator FDTD(SO-FDTD). The dielectric property of magnetized dispersive medium is written as rational polynomial function, the relationship between D and E is deduced in time-domain. And its high accuracy and efficiency are verified by calculating the reflection and transmission coefficients of electromagnetic waves through a collision plasma slab. 相似文献
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In this study, an alternative algorithm is proposed for modeling narrowband and wideband Lorentzian dispersive materials using the finite-difference time-domain (FDTD) method. Previous algorithms for modeling narrowband and wideband Lorentzian dispersive materials using the FDTD method have been based on a recursive convolution technique. They present two different and independent algorithms for the modeling of the narrowband and wideband Lorentzian dispersive materials, known as the narrowband and wideband Lorentzian recursive convolution algorithms, respectively. The proposed alternative algorithm may be used as a general algorithm for both narrowband and wideband Lorentzian dispersive materials modeling with the FDTD method. The second-order motion equation for the Lorentzian materials is employed as an auxilary differential equation. The proposed auxiliary differential-equation-based algorithm can also be applied to solve the borderline case dispersive electromagnetic problems in the FDTD method. In contrast, the narrowband and wideband Lorentzian recursive convolution algorithms cannot be used for the borderline case. A rectangular cavity, which is partially filled with narrowband and wideband Lorentzian dispersive materials, is presented as a numerical example. The time response of the electric field z component is used to validate and compare the results 相似文献