GHz横电磁波室内场分布特性及其用于屏蔽效果测量的研究
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摘要
本文简要地分析了FDTD法(时域有限差分法)的基本原理，详细讨论和解决了如何利用该方法计算GHz横电磁波室(GTEM Cell)内场的分布。解决了所涉及的几个关键技术问题，如GTEM Cell内网格剖分的方法、激励源的设置和计算、边界条件的设置(包括金属板表面的边界条件，GTEM Cell内倾斜面的边界条件和吸收边界条件等)、计算参数的设置和峰值检测等。
系统地研究了GTEM Cell内场分布的特点及在其电磁兼容测量中的应用，包括：空腔GTEM Cell内电磁场的数值计算和测量；放入金属DUT(Device Under Test)后GTEM Cell内电磁场的数值计算；以及两者的分析比较，测量结果和计算结果基本吻合。计算结果表明GTEM Cell的有效工作区内，场分布近似为均匀场，场强的变化小于4dB，可以满足电磁兼容测量的要求。放入机箱后，场的纵向分量(z分量)增大了，表明场的模式发生了变化，横电磁波场的特性变差。
为测量不同屏蔽材料屏蔽效果，文中设计了试验用机箱，研究了利用GTEM Cell测量机箱屏蔽效果的方法，并对采用不同屏蔽材料的机箱的屏蔽效果进行了测量，给出了大量的测量数据和一些有价值的结论。对计算机机箱的屏蔽措施进行了研究和改进，系统地分析了机箱需要屏蔽的部位，采取了相应的屏蔽方法。还测量了一般计算机机箱增加屏蔽措施前后的屏蔽效果和在试验中普遍存在的电缆的天线效应的影响。
The principle result of the FDTD (Finite-Difference Time-Domain) method is set forth concisely in the thesis. Some key technical problems about using the method to calculate the field distribution in GTEM Cell (GHz transverse electromagnetic transmission cell) are discussed in detail and solved. For example, the gridding dissect; inspiring source's setting and calculating; boundary terms' setting (including boundary terms' on slat exterior, boundary terms of slope slant inner GTEM Cell and absorbing boundary terms); calculating parameter's setting and inspecting peak value etc are involved.
The feature of the field distribution in GTEM Cell and its application in EMC is systematically studied here, such as: the numerical value calculation and measure in hollow GTEM Cell; the numerical value calculation in GTEM Cell when metal DUT added; and the analyse and comparison of both results. Through comparison, the calculation results are in accord with the measure results, the field in GTEM Cell's efficient workground is an equal field. In efficiency workground, when the change of electric field intension is less than 4dB, which can meet the need of EMC measure. When adding the metal case, electric field intension increased. This is because, the region which is not nil between the soleplate and core plate is minished; portrait heft (z heft) accretion. Those indicate that the mode of field changed, characteristic of transverse electromagnetic wave become worse.
Shielding measure of computer case is also studied and improved in this thesis. The possible part to be shielded is systematically analyzed, and the shielding method is given relevantly. The case which can be used to do experiments are designed. The method of how to use GTEM Cell to measure the case's shielding effect is studied. The shielding effect with varies shielding material are measured. Quantities of measurement data and valuable conclusion are given. In the end, this thesis also stated the measurement of the shielding
effect to common computers before and after adding shielding materials, and the antenna effect of cable that commonly exists in these experiments.
系统地研究了GTEM Cell内场分布的特点及在其电磁兼容测量中的应用，包括：空腔GTEM Cell内电磁场的数值计算和测量；放入金属DUT(Device Under Test)后GTEM Cell内电磁场的数值计算；以及两者的分析比较，测量结果和计算结果基本吻合。计算结果表明GTEM Cell的有效工作区内，场分布近似为均匀场，场强的变化小于4dB，可以满足电磁兼容测量的要求。放入机箱后，场的纵向分量(z分量)增大了，表明场的模式发生了变化，横电磁波场的特性变差。
为测量不同屏蔽材料屏蔽效果，文中设计了试验用机箱，研究了利用GTEM Cell测量机箱屏蔽效果的方法，并对采用不同屏蔽材料的机箱的屏蔽效果进行了测量，给出了大量的测量数据和一些有价值的结论。对计算机机箱的屏蔽措施进行了研究和改进，系统地分析了机箱需要屏蔽的部位，采取了相应的屏蔽方法。还测量了一般计算机机箱增加屏蔽措施前后的屏蔽效果和在试验中普遍存在的电缆的天线效应的影响。
The principle result of the FDTD (Finite-Difference Time-Domain) method is set forth concisely in the thesis. Some key technical problems about using the method to calculate the field distribution in GTEM Cell (GHz transverse electromagnetic transmission cell) are discussed in detail and solved. For example, the gridding dissect; inspiring source's setting and calculating; boundary terms' setting (including boundary terms' on slat exterior, boundary terms of slope slant inner GTEM Cell and absorbing boundary terms); calculating parameter's setting and inspecting peak value etc are involved.
The feature of the field distribution in GTEM Cell and its application in EMC is systematically studied here, such as: the numerical value calculation and measure in hollow GTEM Cell; the numerical value calculation in GTEM Cell when metal DUT added; and the analyse and comparison of both results. Through comparison, the calculation results are in accord with the measure results, the field in GTEM Cell's efficient workground is an equal field. In efficiency workground, when the change of electric field intension is less than 4dB, which can meet the need of EMC measure. When adding the metal case, electric field intension increased. This is because, the region which is not nil between the soleplate and core plate is minished; portrait heft (z heft) accretion. Those indicate that the mode of field changed, characteristic of transverse electromagnetic wave become worse.
Shielding measure of computer case is also studied and improved in this thesis. The possible part to be shielded is systematically analyzed, and the shielding method is given relevantly. The case which can be used to do experiments are designed. The method of how to use GTEM Cell to measure the case's shielding effect is studied. The shielding effect with varies shielding material are measured. Quantities of measurement data and valuable conclusion are given. In the end, this thesis also stated the measurement of the shielding
effect to common computers before and after adding shielding materials, and the antenna effect of cable that commonly exists in these experiments.
引文
[1] 高攸纲，高思佳．21世纪电磁兼容技术展望[J]．城市管理与科技，2000，2(2)：15～19
[2] 吕仁清、蒋全兴．电磁兼容性结果设计[M]．南京：东南大学出版社，1990：1～10，149～153
[3] 高攸纲．电磁兼容总论[M]．北京：北京邮电大学出版社，2001：1～46
[4] 高攸纲，刁庆安．展望21世纪的环境电磁学与电磁兼容技术(上)[J]．邮电设计技术，1995，5：1～5
[5] 高攸纲，刁庆安．展望21世纪的环境电磁学与电磁兼容技术(下)[J]．邮电设计技术．1995，6：1～7
[6] 曲长云、蒋全兴、吕仁清．电磁发射和敏感度测量[M]．南京：东南大学出版社，1998：1～15，320～360
[7] 张钰．电子机箱的抗电磁干扰设计[J]．江苏机械制造与自动化，1998，4：23～25
[8] 朱元丽，朱元清，张尉．电磁干扰与电磁兼容设计[J]．电脑开发与应用，2000，13(1)：14～15，17
[9] 包安群，王佳．微机保护装置机械结构设计中的电磁屏蔽措施[J]．电力自动化设备，2001，21(7)：55～57
[10] 冉红艳．电子工程系统中电磁干扰的诊断和控制方法初探[J]．自动控制技术，2002，21(4)：26～29
[16] 陈淑凤，马蔚宇，马晓庆．电磁兼容试验技术[M]．北京：北京邮电大学出版社，2001：1～22，76～91
[17] 周佩白，马乃祥．电磁抗扰度(EMS)的测试[J]，华东电力，1999(10)：51～55
[18] M. L. Crawford, Generation of Standard EM fields using TEM transmission cells[J]. IEEE Trans on Electromagnetic Compatibility, 1974, EMC-16: 189～195
[19] D. Konigstein and D. Hansen, Proc. 7~(th) Inter. Symp. on EMC, 127-132, Zurich, 1987
[20] Wilson P. Simulating open area test emission measurements based on data
obtained in a novel broadband TEM Cell. Inc. IEEE. EMC-s, 1989. 171
[21] Konigstein D., Hansen D. A new family of TEM-CelIs with enlarged band width and optimized working volume. In Proc, 7th Zurich Symp., Techn., Exh, on EMC Mar, 1987. 127～132
[22] R De Leo, T Rozzi, C Svara,et al. Rigorous analysis of the GTEM Cell[J]. IEEE Transactions on Microwave Theory and Techniques. 1991. 39(3): 488～500
[23] 黄志洵，王晓金．微波传输线理论与使用技术[M]．北京：科学出版社，1996．16～20
[24] 黄志洵，赵爱军，贺涛．GTEM室内场强分布的计算分析[J]．计量学报．1997．18(1)：63～71
[25] 黄志洵，贺涛．吉赫横电磁室(GTEM)的波分析[J]．宇航计测技术．1994，13(1)：9～17
[26] 王可，黄卡玛，刘宁，马永东．横电磁传输室中生物组织加热过程的分析[J]，电波科学学报．2000，15(1)：80～83
[27] P. F. Wilson, Mark T Ma. Shielding-effectiveness measurements with a dual TEM Cell [J], IEEE Trans on Electromagnetic Compatibility, 1985, EMC-27 (3): 137～143
[28] M. Kanda. Standard antennas for electromagnetic interference measurements and methods to calibrate them [J], IEEE Transactions on Electromagnetic Compatibility, 1994, 36(4): 261～273
[29] 赖祖武．电磁干扰防护与电磁兼容[M]．北京：原子能出版社，1993：65
[30] Yee K. S. Numerical Solution of Initial Boundary Value Problems Involving Maxwell Equations Isotropic Media. IEEE Trans. Antennas Propagat., 1996, AP-15 (5): 302～307
[31] Holland R. THREDE: A Free-Field EMP Coupling and Scattering Code. IEEE Trans on NS, 1977, 24(6): 2416～2421
[32] Gilbert J, Holland R. Implementation of the Thin-Slot Formulism in the Finite-Difference EMP Code THREDEII. IEEE Trans on NS, 1981, 28(6): 4269～4274
[33] Demarest K R. A Finite Difference-Time Domain Technique for Modeling Narrow aperture In Conduction Scatterings. IEEE Trans on AP, 1987, 35(7): 826～831
[34] Taflove A, et al. Detailed FDTD Analysis of Electromagnetic Fields Penetrating Narrow Slots and Lapped Joints in Thick Conducting Screens. IEEE Trans on AP, 1988, 30(2): 247～257
[35] Riley D J, Turner C D. llybird Thin-Slot Algorithm for the Analysis of Narrow Aperture in Finite-Difference Time-Domain Calculations. IEEE Trans on AP. 1990, 38(12): 1943～1950
[36] D Hansen, D Ristau. T Spaeth, et al. Analysis of the measured field structure in a GTEM 1750[C]. In: IEEE International Symposium on Electromagnetic Compatibility. 1994, Symposium Record: 144～149
[37] T E Hamington. GTEM fields FDTD modeling[C]. In: IEEE International Symposium on Electromagnetic Compatibility, 1997: 614～619
[38] 邹澎，周晓萍，高宇．利用三维FDTD法分析非对称横电磁波室内场的分布[J]．微波学报，2000，16(3)：313～317
[39] 张勇军，王龙根，何国瑜．GTEM小室放置被测物后的场分布[J]．宇航计测技术，2001，21(1)：8～16
[40] 王长清，祝里西．电磁场计算中的时域有限差分法[M]．北京：北京大学出版社，1994．1～45
[41] 周斌．用时域有限差分法分析柱面缝隙和贴片微带天线[D]．南京：南京航空航天大学，2002
[42] 倪光正，钱秀英．电磁场数值计算[M]．北京：高等教育出版社，1996：48～55
[43] Mur G. Absorbing Boundary Condition for the Finite-Difference Approximations of the Time-Domain Electromagnetic-Field Equation. IEEE Trans on EMC, 1981, 23(40): 337-382
[44] 王秉中．计算电磁学[M]．北京：科学出版社，2002．1～10
[45] 葛德彪，闫玉波．电磁波时域有限差分法[M]．西安：西安电子科技大学出版社，2002．1～35
[46] 邹澎，周晓萍．放入 DUT 后非对称横电磁波室内场的分布[J]．微波学报，
2002，18 (1)：67～70
[47] 邹澎等．环境电磁场测量[M]．北京：中国计量出版社，1992
[48] 吴景艳，邹澎．机箱电磁屏蔽的理论分析[J]．河南科学，2004，(2)：171～174
[49] 王庆斌 刘萍 尤利文 林啸天 编著．电磁干扰与电磁兼容技术[M]．北京：机械工业出版社，1999．8
[50] 截止波导在电磁屏蔽中的应用 http://www.emi.net.cn/scrap/3/n3_2.asp
[51] 生建友．电子设备的防电磁泄漏技术研究[J]．军事通信技术，1997，63：60～65
[52] 白同云，吕晓德．电磁兼容设计[M]．北京：北京邮电大学出版社，2001
[53] 蔡仁钢．电磁兼容原理设计和预测技术[M]．北京：北京航空航天大学出版社，1997
[2] 吕仁清、蒋全兴．电磁兼容性结果设计[M]．南京：东南大学出版社，1990：1～10，149～153
[3] 高攸纲．电磁兼容总论[M]．北京：北京邮电大学出版社，2001：1～46
[4] 高攸纲，刁庆安．展望21世纪的环境电磁学与电磁兼容技术(上)[J]．邮电设计技术，1995，5：1～5
[5] 高攸纲，刁庆安．展望21世纪的环境电磁学与电磁兼容技术(下)[J]．邮电设计技术．1995，6：1～7
[6] 曲长云、蒋全兴、吕仁清．电磁发射和敏感度测量[M]．南京：东南大学出版社，1998：1～15，320～360
[7] 张钰．电子机箱的抗电磁干扰设计[J]．江苏机械制造与自动化，1998，4：23～25
[8] 朱元丽，朱元清，张尉．电磁干扰与电磁兼容设计[J]．电脑开发与应用，2000，13(1)：14～15，17
[9] 包安群，王佳．微机保护装置机械结构设计中的电磁屏蔽措施[J]．电力自动化设备，2001，21(7)：55～57
[10] 冉红艳．电子工程系统中电磁干扰的诊断和控制方法初探[J]．自动控制技术，2002，21(4)：26～29
[16] 陈淑凤，马蔚宇，马晓庆．电磁兼容试验技术[M]．北京：北京邮电大学出版社，2001：1～22，76～91
[17] 周佩白，马乃祥．电磁抗扰度(EMS)的测试[J]，华东电力，1999(10)：51～55
[18] M. L. Crawford, Generation of Standard EM fields using TEM transmission cells[J]. IEEE Trans on Electromagnetic Compatibility, 1974, EMC-16: 189～195
[19] D. Konigstein and D. Hansen, Proc. 7~(th) Inter. Symp. on EMC, 127-132, Zurich, 1987
[20] Wilson P. Simulating open area test emission measurements based on data
obtained in a novel broadband TEM Cell. Inc. IEEE. EMC-s, 1989. 171
[21] Konigstein D., Hansen D. A new family of TEM-CelIs with enlarged band width and optimized working volume. In Proc, 7th Zurich Symp., Techn., Exh, on EMC Mar, 1987. 127～132
[22] R De Leo, T Rozzi, C Svara,et al. Rigorous analysis of the GTEM Cell[J]. IEEE Transactions on Microwave Theory and Techniques. 1991. 39(3): 488～500
[23] 黄志洵，王晓金．微波传输线理论与使用技术[M]．北京：科学出版社，1996．16～20
[24] 黄志洵，赵爱军，贺涛．GTEM室内场强分布的计算分析[J]．计量学报．1997．18(1)：63～71
[25] 黄志洵，贺涛．吉赫横电磁室(GTEM)的波分析[J]．宇航计测技术．1994，13(1)：9～17
[26] 王可，黄卡玛，刘宁，马永东．横电磁传输室中生物组织加热过程的分析[J]，电波科学学报．2000，15(1)：80～83
[27] P. F. Wilson, Mark T Ma. Shielding-effectiveness measurements with a dual TEM Cell [J], IEEE Trans on Electromagnetic Compatibility, 1985, EMC-27 (3): 137～143
[28] M. Kanda. Standard antennas for electromagnetic interference measurements and methods to calibrate them [J], IEEE Transactions on Electromagnetic Compatibility, 1994, 36(4): 261～273
[29] 赖祖武．电磁干扰防护与电磁兼容[M]．北京：原子能出版社，1993：65
[30] Yee K. S. Numerical Solution of Initial Boundary Value Problems Involving Maxwell Equations Isotropic Media. IEEE Trans. Antennas Propagat., 1996, AP-15 (5): 302～307
[31] Holland R. THREDE: A Free-Field EMP Coupling and Scattering Code. IEEE Trans on NS, 1977, 24(6): 2416～2421
[32] Gilbert J, Holland R. Implementation of the Thin-Slot Formulism in the Finite-Difference EMP Code THREDEII. IEEE Trans on NS, 1981, 28(6): 4269～4274
[33] Demarest K R. A Finite Difference-Time Domain Technique for Modeling Narrow aperture In Conduction Scatterings. IEEE Trans on AP, 1987, 35(7): 826～831
[34] Taflove A, et al. Detailed FDTD Analysis of Electromagnetic Fields Penetrating Narrow Slots and Lapped Joints in Thick Conducting Screens. IEEE Trans on AP, 1988, 30(2): 247～257
[35] Riley D J, Turner C D. llybird Thin-Slot Algorithm for the Analysis of Narrow Aperture in Finite-Difference Time-Domain Calculations. IEEE Trans on AP. 1990, 38(12): 1943～1950
[36] D Hansen, D Ristau. T Spaeth, et al. Analysis of the measured field structure in a GTEM 1750[C]. In: IEEE International Symposium on Electromagnetic Compatibility. 1994, Symposium Record: 144～149
[37] T E Hamington. GTEM fields FDTD modeling[C]. In: IEEE International Symposium on Electromagnetic Compatibility, 1997: 614～619
[38] 邹澎，周晓萍，高宇．利用三维FDTD法分析非对称横电磁波室内场的分布[J]．微波学报，2000，16(3)：313～317
[39] 张勇军，王龙根，何国瑜．GTEM小室放置被测物后的场分布[J]．宇航计测技术，2001，21(1)：8～16
[40] 王长清，祝里西．电磁场计算中的时域有限差分法[M]．北京：北京大学出版社，1994．1～45
[41] 周斌．用时域有限差分法分析柱面缝隙和贴片微带天线[D]．南京：南京航空航天大学，2002
[42] 倪光正，钱秀英．电磁场数值计算[M]．北京：高等教育出版社，1996：48～55
[43] Mur G. Absorbing Boundary Condition for the Finite-Difference Approximations of the Time-Domain Electromagnetic-Field Equation. IEEE Trans on EMC, 1981, 23(40): 337-382
[44] 王秉中．计算电磁学[M]．北京：科学出版社，2002．1～10
[45] 葛德彪，闫玉波．电磁波时域有限差分法[M]．西安：西安电子科技大学出版社，2002．1～35
[46] 邹澎，周晓萍．放入 DUT 后非对称横电磁波室内场的分布[J]．微波学报，
2002，18 (1)：67～70
[47] 邹澎等．环境电磁场测量[M]．北京：中国计量出版社，1992
[48] 吴景艳，邹澎．机箱电磁屏蔽的理论分析[J]．河南科学，2004，(2)：171～174
[49] 王庆斌 刘萍 尤利文 林啸天 编著．电磁干扰与电磁兼容技术[M]．北京：机械工业出版社，1999．8
[50] 截止波导在电磁屏蔽中的应用 http://www.emi.net.cn/scrap/3/n3_2.asp
[51] 生建友．电子设备的防电磁泄漏技术研究[J]．军事通信技术，1997，63：60～65
[52] 白同云，吕晓德．电磁兼容设计[M]．北京：北京邮电大学出版社，2001
[53] 蔡仁钢．电磁兼容原理设计和预测技术[M]．北京：北京航空航天大学出版社，1997