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1.
小孔矩形腔体屏蔽特性的研究 总被引:3,自引:0,他引:3
本文提出了有孔腔体远、近场电磁屏蔽效能的计算方法,体研究了矩形腔体的屏蔽特性,讨论了各类孔对屏蔽能的影响程度。数值结果表明,理论计算与实验数据吻合较好。 相似文献
2.
Min Li Nuebel J. Drewniak J.L. DuBroff R.E. Hubing T.H. Van Doren T.P. 《Electromagnetic Compatibility, IEEE Transactions on》2000,42(3):265-275
Aperture arrays designed to provide airflow through shielding enclosures can provide part of the coupling path from interior sources to external electromagnetic interference (EMI). In this work, radiation through aperture arrays is investigated numerically and experimentally. FDTD modeling is compared with measurements on aperture arrays in a test enclosure. The method of moments (MoM) is also utilized to study radiation from apertures and to investigate the mutual coupling between apertures in an infinite conducting plane. A simple design equation for the relation between aperture size and number and shielding effectiveness is proposed 相似文献
3.
《Electromagnetic Compatibility, IEEE Transactions on》2008,50(4):928-939
4.
Shielding effectiveness of metallic enclosures at oblique and arbitrary polarizations 总被引:1,自引:0,他引:1
Khan Z.A. Bunting C.F. Deshpande M.D. 《Electromagnetic Compatibility, IEEE Transactions on》2005,47(1):112-122
Shielding effectiveness of metallic enclosures with apertures when illuminated by an oblique incidence arbitrary polarized plane wave has been studied by using an efficient hybrid modal/moment technique. Shielding effectiveness of rectangular enclosures with one, two, and four apertures at multiple points inside the enclosures for various frequencies has been calculated when the illuminating source flies by the front of the enclosure. The work shows that the shielding effectiveness is seriously affected by frequency, angle of incidence and polarization of the illuminating field; the number and orientation of apertures; and the location inside the cavity. It has been shown that the usual assumption about the normal incidence being the worst-case scenario for shielding effectiveness values may not be valid when there is more than one aperture in the cavity. The paper emphasizes the need for the statistical investigation of shielding effectiveness problem of metallic enclosures with apertures. 相似文献
5.
Efficient EMC Simulation of enclosures with apertures residing in an electrically large platform using the MM-UTD method 总被引:2,自引:0,他引:2
The moment method coupled with the uniform theory of diffraction is employed in this paper to simulate the electromagnetic shielding performance of an enclosure with apertures residing in a very large platform, in which the moment method is used to accurately model the enclosure with apertures, and the influence of the large platform is efficiently calculated by using the uniform theory of diffraction. These two methods are coupled through the tangential electromagnetic fields on the apertures of the enclosure. In this paper, the accuracy of this coupled method developed is validated, and we apply this method for simulating the shielding effectiveness with the sources inside/outside the enclosure. The simulation results show that this coupled technique is able to simultaneously model the effects of the smaller structures and the large platform on the total electromagnetic property. It further demonstrates that this coupled method is a very flexible and powerful technique for analysis of the electromagnetic compatibility problems with smaller objects mounted on a larger platform. 相似文献
6.
为研究任意入射角度平面波对多面开孔腔体的孔缝耦合效应,根据矢量分析和矩形波导内场强分布对等效传输线法进行了改进,计算了多面开孔腔体内任意位置的屏蔽效能。将改进等效传输线法计算结果与CST仿真结果、实验测量结果进行比较,验证了改进等效传输线法的正确性,相比数值计算方法,改进等效传输线法所需计算时间和内存更少。采用改进等效传输线法对相同体积不同尺寸的多面开孔腔体的屏蔽效能进行了研究,结果表明:在相同体积下,腔体为正方体时的屏蔽效能和其他尺寸腔体的屏蔽效能基本一致,但是正方形的屏蔽效能极小值点大大减少,从而减少了电子设备受电磁干扰的几率。 相似文献
7.
Reddy C.J. Deshpande M.D. Cockrell C.R. Beck F.B. 《Antennas and Propagation, IEEE Transactions on》1996,44(10):1327-1333
A technique using the hybrid finite element method (FEM)/method of moments (MoM) and geometrical theory of diffraction (GTD) is presented to analyze the radiation characteristics of cavity fed aperture antennas in a finite ground plane. The cavity which excites the aperture is assumed to be fed by a cylindrical transmission line. The electromagnetic (EM) fields inside the cavity are obtained using finite element method (FEM). The EM fields and their normal derivatives required for FEM solution are obtained using: (1) the modal expansion in the feed region and (2) the MoM for the radiating aperture region (assuming an infinite ground plane). The finiteness of the ground plane is taken into account using GTD. The input admittance of open-ended circular, rectangular, and coaxial line radiating into free space through an infinite ground plane are computed and compared with earlier published results. Radiation characteristics of a coaxial cavity-fed circular aperture in a finite rectangular ground plane are verified with experimental results 相似文献
8.
电子设备屏蔽效能的好坏直接影响着电路系统的电磁兼容性能,而其金属壳体上的孔缝造成的电磁泄漏是一个不容忽视的问题。以内置电路板的开缝屏蔽壳体为研究对象,应用FEM(有限元法)分析了不同的孔缝尺寸、电路板尺寸、电路板位置对壳体屏蔽效能的影响。并进一步研究了电路板上金属微带线受电磁干扰信号影响而产生感应电流的变化规律:走线越长,离缝隙越近,感应电流数值越大,其峰值出现在腔体的谐振频率处。根据计算结果,提出了优化设计屏蔽腔及其腔内电子设备的建议。本文研究对于更为有效地利用金属壳体防御电磁干扰,提高系统电磁兼容性具有指导意义。 相似文献
9.
Xian-jin Li Bi-hua Zhou Tong-bin Yu Gao Cheng Li-hua Shi Chun-Lan Lu 《Electromagnetic Compatibility, IEEE Transactions on》2007,49(1):133-142
Due to a nearby lightning return stroke, the coupled electromagnetic (EM) fields inside a rectangular shielding enclosure, on the finitely conducting ground, with an aperture in one wall are calculated numerically by using the finite-difference time-domain (FDTD) method. First, the near fields generated by the return stroke are obtained in two-dimensional (2-D) cylindrical coordinates by the FDTD method. Then, the coupled fields inside a rectangular shielding enclosure are calculated in three-dimensional (3-D) rectangular coordinates through the total field-scattered field connecting boundary, with the sources obtained by coordinates transformations of the return stroke near fields 相似文献
10.
Analoni M. Kagawa Y. Kagami Y. Nishimura F. 《Electromagnetic Compatibility, IEEE Transactions on》1995,37(3):443-448
High-frequency (HF) operated lamps, such as HF fluorescent lamps, have several advantages over conventional ones but they contaminate the environment with their EM field emissions. The shielding of the electromagnetic emission should be realized without much effect on the emission of the light. Enclosing the lamps in a housing made of widely spaced thin wires could be an appropriate way to shield the electromagnetic field. The paper studies the effectiveness of some wire structures for shielding the electromagnetic emission from HF fluorescent lamps. An analytical study, method of moments (MoM), and measurements have been carried out to evaluate the strength of the near-field and the shielding effectiveness of the structures 相似文献
11.
Validation of modal/MoM in shielding effectiveness studies of rectangular enclosures with apertures 总被引:1,自引:0,他引:1
Rajamani V. Bunting C.F. Deshpande M.D. Khan Z.A. 《Electromagnetic Compatibility, IEEE Transactions on》2006,48(2):348-353
This paper discusses the validation of Modal/method of moments (MoM) including cases when the apertures are made as big as the wall of the enclosure (equivalent to having one side of the cavity open). The validation is done using field computations involving bodies of arbitrary shape (FEKO), a commercially available code. The results show that Modal/MoM predicts the results close to the analytical results of Robinson et al. Electron. Lett., 32 (17), 1996; Robinson et al., IEEE Trans. Electromagn. Compat., 40 (3), 240-247, 1998 for single-aperture cases and for most double-aperture cases. Also, for the cases of considering oblique incident plane waves, through validation, it has been found that Modal/MoM can predict the shielding effectiveness close to measured results for smaller angles and not for larger angles of incidence due to the edge effects. In this work, the shielding effectiveness is calculated at only one point, the center of the cavity assuming it to be the worst case. This work discovers the limitation of Modal/MoM for certain applications. 相似文献
12.
13.
Wallyn W. De Zutter D. Rogier H. 《Electromagnetic Compatibility, IEEE Transactions on》2002,44(1):130-138
A new method of moments (MoM) formulation is proposed to evaluate the shielding efficiency of metallic rectangular enclosures. To this end, a mixed potential integral equation (MPIE) is formulated for the magnetic currents in the apertures using the exact Green's function of the enclosure. The accuracy of the method is demonstrated by a number of examples. The method allows the quality factor of the resonances to be predicted. Finally, the effect of partitioning the enclosure by metallic planes is also investigated 相似文献
14.
Electromagnetic wave penetration into a rectangular cavity with multiple rectangular apertures is studied. The Fourier transform and the mode matching method are used to obtain simultaneous equations for the modal coefficients. The simultaneous equations are solved to represent the cavity field in series forms, which are suitable for numerical computations. Numerical computations are performed to investigate the field penetration into a cavity in terms of the shielding effectiveness for a various geometry 相似文献
15.
Jui-Ching Cheng Dib N.I. Katehi L.P.B. 《Antennas and Propagation, IEEE Transactions on》1995,43(9):1003-1013
A hybrid technique that combines the method of moments (MoM) and the finite element method (FEM) to analyze cavity-backed patch antennas is presented. This technique features the use of FEM in solving the electromagnetic field distribution in the cavity and the use of MoM in solving integral equations outside the cavity. The results of MoM and FEM are combined through the continuity conditions on the boundary of the cavity. Due to the flexibility of FEM, complex cavities filled with inhomogeneous media can be analyzed by this technique. The results obtained by this hybrid technique are compared to the finite difference time domain (FDTD) results and good agreement is found 相似文献
16.
为研究双面含孔矩形金属腔体的屏蔽效能问题,运用矢量分解和等效传输线相结合的原理,给出了双面含单孔的矩形金属腔体内部中心点屏蔽效能计算方法,通过与电磁数值软件CST 的计算结果对比,验证了该计算方法的有效性,且耗时少、收敛快,运用该方法进一步研究了双面含孔阵矩形金属腔体屏蔽效能,得到了腔体内部多模谐振规律。在共振频率附近,腔体内中心点的耦合电场较强,当频率低于主频谐振时,屏蔽效能随着频率的降低而增大;在2GHz 频率范围内,腔体内部各个方向的屏蔽效能都存在多模谐振的现象,且谐振模式不相同;开有相同面积的孔阵屏蔽效能比单孔差,谐振模式变化不大。 相似文献
17.
Ali S. Weile D.S. Clupper T. 《Electromagnetic Compatibility, IEEE Transactions on》2005,47(2):367-373
The electromagnetic coupling through an infinite conducting sheet perforated with a finite array of apertures excited by a metal radiator placed in its near field is investigated. The coupling is analyzed numerically by the method of moments (MoM) with an emphasis on understanding the effect of the interactions between the array of apertures and the metal radiator placed in its proximity. The radiation leakage through the array of apertures is found to be significant due to the proximity to the antenna, even if the apertures are electrically small. The effect of a number of other factors like antenna size, antenna type, aperture spacing, and aperture sizes on the extent of radiation leakage occurring due to coupling between the array of apertures and the radiator is also investigated. Numerical results confirm that plane wave theory underestimates the electromagnetic coupling through small apertures by antennas placed in their near field. 相似文献
18.
Robinson M.P. Benson T.M. Christopoulos C. Dawson J.F. Ganley M.D. Marvin A.C. Porter S.J. Thomas D.W.P. 《Electromagnetic Compatibility, IEEE Transactions on》1998,40(3):240-248
An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with an aperture. Both the magnetic and electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Theoretical values of shielding effectiveness are in good agreement with measurements. The theory has been extended to account for circular apertures, multiple apertures, and the effect of the enclosure contents 相似文献
19.
Yong-Lun Luo Kwai-Man Luk Siu-Ming Shum 《Antennas and Propagation, IEEE Transactions on》1998,46(12):1833-1841
The finite-difference (FD) method is a basic technique for solving differential equations. The disadvantage of it for electromagnetic (EM) problems of an open region is that the mesh needs to be terminated with the application of a proper boundary condition. In this paper, a novel exact two-point field equation (2PFE) is derived from rigorous analysis of the radiation field and it is proposed to be used as the termination boundary condition (BC) for solving EM scattering problems in the open region by the iterative FD method. This 2PFE-BC approaches its exact solution through the iteration process and, at the same time, the scattered field and the induced current density approach their exact solutions. The novel 2PFE is simple in concept and easy to apply. The validity of the 2PFE and the iterative FD method has been tested. Several two-dimensional (2-D) scattering problems have been successfully solved. The results agree very well with those obtained by method of moments (MoM) or measured equation of invariance (MEI) 相似文献
20.
《Antennas and Propagation, IEEE Transactions on》2009,57(5):1452-1460