volume | PIER Journals

Abstract

An analytical model based on the Bethe's theory of diffraction by small holes is presented to predict the shielding effectiveness (SE) of metallic rectangular enclosure with electrically large aperture under plane wave illumination over a wide frequency range (0~3 GHz). In this model, the aperture is represented as electric and magnetic dipoles located at the center of the aperture, and the coupling relation between external plane wave and electromagnetic field inside the enclosure is established. The approximate solution of electromagnetic field distribution inside the enclosure is obtained in terms of the integrals of the electric and magnetic dynamic Green function. Finally, the influence of enclosure thickness on SE is calculated by introducing thickness attenuation coefficient. The model considers the effect of the thickness on the calculation results and is simple with low computation complex and high estimation accuracy. Besides, the effects of parameters like enclosure and aperture dimensions, aperture and observation point positions, incident and polarization direction of the plane wave on SE can be analyzed comprehensively based on the model. Simulation results of the proposed model are in accord with that of the TLM method, which verifies the accuracy and reliability of the model.

1. Carpes, W. P., Jr., et al. "TLM and FEM methods applied in the analysis of electromagnetic coupling," IEEE Transactions on Magnetics, Vol. 36, No. 4, 982-985, 2000.
doi:10.1109/20.877606

2. Dehkhoda, P., A. Tavakoli, and M. Azadifar, "Shielding effectiveness of an enclosure with finite wall thickness and perforated opposing walls at oblique incidence and arbitrary polarization by GMMoM," IEEE Transactions on Electromagnetic Compatibility, Vol. 54, No. 4, 792-805, 2012.
doi:10.1109/TEMC.2012.2188855

3. Jiao, C., et al. "Subcell FDTD analysis of shielding effectiveness of a thin-walled enclosure with an aperture," IEEE Transactions on Magnetics, Vol. 42, No. 4, 1075-1078, 2006.
doi:10.1109/TMAG.2006.871638

4. Robinson, M. P., et al. "Shielding effectiveness of a rectangular enclosure with a rectangular aperture," Electronics Letters, Vol. 32, No. 17, 1559-1560, 1996.
doi:10.1049/el:19961030

5. Po'Ad, F. A., et al. "Analytical and experimental study of the shielding effectiveness of a metallic enclosure with off-centered apertures," International Zurich Symposium on Electromagnetic Compatibility, 2006, Emc-Zurich, 618-621, IEEE Xplore, 2006.

6. Dan, S., Y. Shen, and Y. Gao, "3 high-order mode transmission line model of enclosure with off-center aperture," International Symposium on Electromagnetic Compatibility, 361-364, IEEE, 2007.

7. Nie, B. L. and P. A. Du, "An efficient and reliable circuit model for the shielding effectiveness prediction of an enclosure with an aperture," IEEE Transactions on Electromagnetic Compatibility, Vol. 57, No. 3, 357-364, 2015.
doi:10.1109/TEMC.2014.2383438

8. Liu, E., P. A. Du, and B. Nie, "An extended analytical formulation for fast prediction of shielding effectiveness of an enclosure at different observation points with an off-axis aperture," IEEE Transactions on Electromagnetic Compatibility, Vol. 56, No. 3, 589-598, 2014.
doi:10.1109/TEMC.2013.2289742

9. Azaro, R., et al. "A circuital approach to evaluating the electromagnetic field on rectangular apertures backed by rectangular cavities," IEEE Transactions on Microwave Theory & Techniques, Vol. 50, No. 10, 2259-2266, 2002.
doi:10.1109/TMTT.2002.803434

10. Konefal, T., et al. "A fast multiple mode intermediate level circuit model for the prediction of shielding effectiveness of a rectangular box containing a rectangular aperture," IEEE Transactions on Electromagnetic Compatibility, Vol. 47, No. 4, 678-691, 2006.
doi:10.1109/TEMC.2005.853715

11. Yin, M. C. and P. A. Du, "An improved circuit model for the prediction of the shielding effectiveness and resonances of an enclosure with apertures," IEEE Transactions on Electromagnetic Compatibility, Vol. 58, No. 2, 448-456, 2016.
doi:10.1109/TEMC.2016.2517163

12. Shim, J., et al. "Circuital modeling and measurement of shielding effectiveness against oblique incident plane wave on apertures in multiple sides of rectangular enclosure," IEEE Transactions on Electromagnetic Compatibility, Vol. 52, No. 3, 566-577, 2010.
doi:10.1109/TEMC.2009.2039483

13. Hao, J.-H., P.-H. Qi, J.-Q. Fan, and Y.-Q. Guo, "Analysis of shielding effectiveness of enclosures with apertures and inner windows with TLM," Progress In Electromagnetic Research M, Vol. 32, 73-82, 2013.
doi:10.2528/PIERM13060312

14. Solin, J. R., "Formula for the field excited in a rectangular cavity with a small aperture," IEEE Transactions on Electromagnetic Compatibility, Vol. 53, No. 1, 82-90, 2011.
doi:10.1109/TEMC.2010.2053711

15. Solin, J. R., "Formula for the field excited in a rectangular cavity with an electrically large aperture," IEEE Transactions on Electromagnetic Compatibility, Vol. 54, No. 1, 188-192, 2012.
doi:10.1109/TEMC.2011.2179941

16. Tesche, F. M., M. V. Ianoz, and T. Karlsson, EMC Analysis Methods and Computational Models, Wiley, 1997.

17. Cohn, S. B., "Microwave coupling by large apertures," Proceedings of the IRE, Vol. 40, No. 6, 696-699, 1952.
doi:10.1109/JRPROC.1952.274063

18. Pozar, D. M., Microwave Engineering, Academic, 2006.

19. Mcdonald, N. A., "Polynomial approximations for the electric polarizabilities of some small apertures," IEEE Xplore, Vol. 33, No. 11, 1146-1149, 1985.

20. Mcdonald, N. A., "Polynomial approximations for the transverse magnetic polarizabilities of some small apertures," IEEE Transactions on Microwave Theory & Techniques, Vol. 35, No. 1, 20-23, 2003.
doi:10.1109/TMTT.1987.1133589

21. Mcdonald, N. A., "Simple approximations for the longitudinal magnetic polarizabilities of some small apertures," IEEE Transactions on Microwave Theory & Techniques, Vol. 36, No. 7, 1141-1144, 2002.
doi:10.1109/22.3648

22. Nitsch, J. B., S. V. Tkachenko, and S. Potthast, "Transient excitation of rectangular resonators through electrically small circular holes," IEEE Transactions on Electromagnetic Compatibility, Vol. 54, No. 6, 1252-1259, 2012.
doi:10.1109/TEMC.2012.2201724

23. Li, L. W., et al. "On the eigenfunction expansion of electromagnetic dyadic Green's functions in rectangular cavities and waveguides," IEEE Transactions on Microwave Theory & Techniques, Vol. 43, No. 3, 700-702, 1995.
doi:10.1109/22.372122

24. Crawhall, R. J. H., EMI Potential of Multiple Sources within a Shielded Enclosure, 1993.

25. Goudos, S. K., E. E. Vafiadis, and J. N. Sahalos, "Monte Carlo simulation for the prediction of the emission level from multiple sources inside shielded enclosures," IEEE Transactions on Electromagnetic Compatibility, Vol. 44, No. 2, 291-308, 2002.
doi:10.1109/TEMC.2002.1003394

Dr. Pu-Yu Hu

Dr. Xiaoying Sun