共查询到20条相似文献,搜索用时 31 毫秒
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Min Li Kuang-Ping Ma Hockanson D.M. Drewniak J.L. Hubing T.H. Van Doren T.P. 《Electromagnetic Compatibility, IEEE Transactions on》1997,39(3):225-232
Simple design maxims to restrict slot dimensions in enclosure designs below a half-wave length are not always adequate for minimizing electromagnetic interference (EMI). Complex interactions between cavity modes, sources, and slots can result in appreciable radiation through nonresonant length slots. The finite-difference time domain (FDTD) method can be employed to pursue these issues with adequate modeling of thin slots. Subcellular FDTD algorithms for modeling thin slots in conductors have previously been developed. One algorithm based on a quasistatic approximation has been shown to agree well with experimental results for thin slots in planes. This FDTD thin-slot algorithm is compared herein with two-dimensional (2-D) moment method results for thin slots near corners and plane wave excitation. FDTD simulations are also compared with measurements for slots near an edge of a cavity with an internal source 相似文献
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Min Li Nuebel J. Drewniak J.L. DuBroff R.E. Hubing T.H. van Doren T.P. 《Electromagnetic Compatibility, IEEE Transactions on》2000,42(1):29-38
Electromagnetic interference (EMI) from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a rectangular test enclosure is reported. EMI from a specially designed test enclosure with slots or apertures excited by interior sources was studied experimentally and with finite-difference time-domain (FDTD) modeling. The measurements and FDTD modeling agree well. The results indicate that radiation at cavity mode resonances through slots and apertures of nonresonant dimensions can be as significant as the radiation at aperture or slot resonances. The agreement between the FDTD modeling and measurements demonstrates the usefulness of FDTD for investigating aspects of shielding enclosure design such as coupling to slots and apertures and slot interactions 相似文献
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A subcell model for thin wires in the finite-difference time-domain (FDTD) method using modified telegraphers equations has been developed by Holland et al. Edelvik has previously presented an extension of their algorithm, which allows for arbitrarily located and oriented wires with respect to the Cartesian grid. This is important to be able to accurately model wires that cannot be aligned to the Cartesian grid, e.g., tilted wires and circular loop wires. Recently, a dual set of equations has been proposed for modeling of thin slots. In this paper, we show that using a similar algorithm as for thin wires we can also handle slots of arbitrary location in Cartesian planes. Previous thin slot models have been susceptible for instabilities. We show that a symmetric coupling between field and slot yields a stable time-continuous field-slot system and that the fully discrete field-slot system is stable under a generalized Courant-Friedrich-Lewy (CFL) condition. The proposed method is demonstrated for scattering from a finite-length slot in an infinite conducting wall and a shielding enclosure including a slot. The results are in good agreement with published experimental data. 相似文献
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Denecker B. Olyslager F. Knockaert L. De Zutter D. 《Antennas and Propagation, IEEE Transactions on》2003,51(8):1806-1817
Adapted finite-difference time-domain (FDTD) update equations exist for a number of objects that are smaller than the grid step, such as wires and thin slots. We provide a technique that automatically generates new FDTD update equations for small objects. Our presentation focusses on 2D-FDTD. We start from the FDTD equations in a fine grid where the time derivative is not discretised. This yields a large state-space model that is drastically reduced with a reduced order modeling technique. The reduced state-space model is then translated into new FDTD update equations that can be used in an FDTD simulation in the same way as the existing update equations for wires and thin slots. This technique is applied to a number of numerical problems showing the accuracy and versatility of the proposed method. 相似文献
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Wu Ren Ben-Qing Gao Zheng-Hui Xue Wei-Ming Li Bo Liu 《Antennas and Propagation, IEEE Transactions on》2004,52(9):2436-2444
A rigorous analysis of the resonant characteristics for a broad wall waveguide slot by using the finite-difference time-domain method is presented. Four types of slots including a radiating longitudinal shunt slot, a longitudinal/transverse coupling slot, a centered-inclined coupling slot and a compound coupling slot are analyzed. Lots of slot characteristics such as the resonant length, scattering parameters and normalized admittance in different offsets, tilt angles or slot sizes are obtained. Because the shape of slots is a rectangle with rounded ends in practical fabrication, an accurate modeling and computation for the slots with rounded ends is implemented, and the resonant lengths calculated coincide well with the Stegen's measured data and method of moments results. From these computed results, it is found that all the resonant characteristics of the slots with rounded ends are significantly different from those with normal rectangular ends. 相似文献
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The authors present two methods for incorporating slot wall loss into the finite-difference time-domain (FDTD) calculations. The walls are assumed to be good conductors. Loss is only applied to the current component that flows axially along the slot walls, which is generally the dominant component for slots that are long and narrow. The first method modifies an FDTD equation internal to the slot to include a surface-impedance contribution. This method is appropriate for the usual FDTD thin-slot formalisms. The second method includes the losses into a half-space integral equation that can be used by the recently introduced hybrid thin-slot algorithm. Results based on the two methods are compared for a variety of slot parameters and wall conductivities 相似文献
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Folded slot antennas are attractive for active arrays due to relatively large bandwidth, fabrication simplicity, and ease of integration with devices. Currently, there is little design information for these antennas, especially on thin substrates. The finite-difference time-domain (FDTD) method is applied to the analysis of CPW-fed folded-slot antennas. The paper describes the problems encountered in the analysis, compares the theoretical results and measured data, and provides some design information for folded slots. In addition, it explores the manipulation of input impedance through the use of additional slots, yielding antennas with a broadband 50 Ω input impedance 相似文献
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《Electromagnetic Compatibility, IEEE Transactions on》2009,51(2):284-292
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一种新型矩形波导裂缝天线的分析与设计 总被引:8,自引:0,他引:8
针对任意两个横缝位于馈电矩形波导终端的短路圆盘上的情况.本文运用伽略金方法分析了一种新型双裂缝天线的反射与辐射特性:分析中考虑了缝隙间的内部互耦与外部互耦:根据分析结果,首次设计并研制了这种工作于C波段的新型天线,实验结果和设计指标吻合较好.它适合高速飞行器载体的特殊应用. 相似文献
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Planar infinite arrays, comprising longitudinal slots cut in ridged waveguides, are analysed using a Galerkin formulation for the tangential electric field at both slot interfaces, combined with the finite element method for generating the waveguide Green function used in the integral equation. Computations agree very well with previously documented results 相似文献
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用时域有限差分法对缝隙渐变天线的瞬态电磁场分析 总被引:2,自引:0,他引:2
本文用时域有限差分(FDTD)法分析缝隙渐变天线,分析中对天线缝隙边缘场和薄天线衬底采取了特殊的处理方法,求天线的远区辐射场采用了FDTD中近场到远场的变换方法。本文计算出的缝隙渐变天线的辐射方向图和远区辐射场与实验结果比较一致。本文给出了超短电磁脉冲在天线上传播和辐射过程的瞬态直观图象,同时还研究了这种天线衬底厚度、几何尺寸及介电常数对其辐射特性及频带的影响。 相似文献
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微波脉冲窄缝耦合的数值模拟方法 总被引:3,自引:0,他引:3
本文应用一种近似方法,结合时域有限差分法,模拟了微波脉冲与腔体上有限厚度孔缝的线性耦合过程,给出了耦合场对入射波载频、入射场偏振方向、腔体壁电导率以及孔缝尺寸的依赖关系,得出了微波脉冲与孔缝耦合的共振效应和增强效应等规律。 相似文献
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The design of large waveguide arrays of shunt slots 总被引:3,自引:0,他引:3
It is shown that the method of moments (MM) solution can determine the active admittance of each slot in a finite array and that the infinite array model is quite accurate for the design of large waveguide arrays of shunt slots. Active admittances computed by an infinite array model agree favorably with that of slots in sufficiently large finite arrays. Measured results verify the MM solution, thereby validating the infinite array model accuracy 相似文献
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In this paper, a time domain method is introduced for analyzing microstrip antennas having thin slots. The present method is based on a resolution of Maxwel?s. equtions using the finite difffreence time domain method. A particular investigation has been made for taking thin slots into account, this avoids a prohibitive grid to represent the slots. Two kinds of antennas have been analyzed by this method: the slot antennas and the radiatins patch fed by a line through a slot. 相似文献
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Theory and analysis of leaky coaxial cables with periodic slots 总被引:4,自引:0,他引:4
Frequency band and coupling loss are the two important parameters of leaky coaxial cables with periodic slots. The frequency band can be predicted by analyzing the arrangement of the slots on the outer shield of the cable, but the coupling loss is not so easy to determine by classical methods. In this paper, the finite-difference time-domain (FDTD) method is used to calculate the electric field distribution in the slot cut in the outer conductor of the coaxial cable. The dyadic Green's function is then used to calculate the radiation field of the equivalent surface magnetic current densities. By these two methods, the coupling losses of the leaky coaxial cables with different periods, sizes and shapes of the slots can be accurately obtained. Some results in this paper were verified by the experimental results of leaky coaxial cables designed for railway mobile communications with a frequency band of 100-500 MHz 相似文献