The shielding cavity loaded with electronic equipment inside has a high Q value and is in overmode at relatively high frequency as a reverberation chamber (RC), but it does not have stirrers or paddles. However, the electromagnetic environment in the cavity is similar to that in the reverberation chamber working in frequency stirring mode or source stirring mode because of the certain bandwidth of the electronic equipment and the movement of the portable electronic equipment. Therefore, the electric field in the cavity can be predicted based on the theory of reverberation chamber. In order to predict the electric field in a given shielding cavity after loading additional electronic equipment, the determination method of the Q value of the cavity and the absorption cross section (ACS) of the electronic equipment, the influence of the ACS on the Q value of the cavity, and the relationship between the Q value and electric field are analyzed Firstly, the ACS and radiated emission power of the loading electronic equipment are measured in the RC. Then, the Q value of the cavity with the electronic equipment loaded inside is calculated by the known Q value of the cavity without the electronic equipment and the ACS of the electronic equipment. Finally, the electric field in the cavity loaded with electronic equipment is estimated by using the calculated Q value of the loaded cavity and the measured radiated emission power of the electronic equipment. The experimental results verify the effectiveness of the prediction method.
1. Siah, E. S., K. Sertel, J. L. Volakis, V. V. Liepa, and R. Wiese, "Coupling studies and shielding techniques for electromagnetic penetration through apertures on complex cavities and vehicular platforms," IEEE Transactions on Electromagnetic Compatibility, Vol. 45, No. 2, 245-256, 2003. doi:10.1109/TEMC.2003.810814
2. Hill, D. A., Electromagnetic Fields in Cavities: Deterministic and Statistical Theories, Wiley-IEEE Press, New Jersey, 2009. doi:10.1002/9780470495056.app5
3. Tait, G. B., C. E. Hager Iv, T. T. Baseler, and M. B. Slocum, "Ambient power density and electric field from broadband wireless emissions in a reverberant space," IEEE Transactions on Electromagnetic Compatibility, Vol. 58, No. 1, 307-313, 2016. doi:10.1109/TEMC.2015.2503925
4. Gros, J. B., O. Legrand, F. Mortessagne, E. Richalot, and K. Selemani, "Universal behaviour of a wave chaos based electromagnetic reverberation chamber," Wave Motion, Vol. 51, No. 4, 664-672, 2014. doi:10.1016/j.wavemoti.2013.09.006
5. Romero, S. F., G. Gutierrez, and I. Gonzalez, "Universal behaviour of a wave chaos based electromagnetic reverberation chamber," Prediction of the Maximum Electric Field Level Inside a Metallic Cavity Using a Quality Factor Estimation, Vol. 28, No. 12, 1468-1477, 2014.
6. Gradoni, G., D. Micheli, F. Moglie, and V. Mariani Primiani, "Absorbing cross section in reverberation chamber: Experimental and numerical results," Progress In Electromagnetics Research B, Vol. 45, 187-202, 2012. doi:10.2528/PIERB12090801
7. Gifuni, A., H. Khenouchi, and G. Schirinzi, "Performance of the reflectivity measurement in a reverberation chamber," Progress In Electromagnetics Research, Vol. 154, 87-100, 2015. doi:10.2528/PIER15072903
8. Yu, S. P. and C. F. Bunting, "Statistical investigation of frequency-stirred reverberation chambers," 2003 IEEE Symposium on Electromagnetic Compatibility. Symposium Record (Cat. No. 03CH37446), Vol. 1, 155-159, 2003.
9. Zhou, Z., P. Hu, X. Zhou, J. Ji, and Q. Zhou, "Performance evaluation of oscillating wall stirrer in reverberation chamber using correlation matrix method and modes within Q-bandwidth," IEEE Transactions on Electromagnetic Compatibility, Vol. 62, No. 6, 2669-2678, 2020, doi: 10.1109/TEMC.2020.2983981. doi:10.1109/TEMC.2020.2983981
10. West, J. C., J. N. Dixon, N. Nourshamsi, D. K. Das, and C. F. Bunting, "Best practices in measuring the quality factor of a reverberation chamber," IEEE Transactions on Electromagnetic Compatibility, Vol. 60, No. 3, 564-571, 2018. doi:10.1109/TEMC.2017.2753724
11. Ji, J., X. Zhou, and P. Hu, "Frequency-dependent oscillating wall stirrer for measurement of quality factor in a reverberation chamber," 2019 IEEE International Conference on Computation, Communication and Engineering (ICCCE), 142-145, 2019. doi:10.1109/ICCCE48422.2019.9010772
12. West, J. C., V. Rajamani, and C. F. Bunting, "Frequency- and time-domain measurement of reverberation chamber Q: An in-silico analysis," 2016 IEEE International Symposium on Electromagnetic Compatibility, 7-12, 2016. doi:10.1109/ISEMC.2016.7571566
13. Hill, D. A., M. T. Ma, A. R. Ondrejka, B. F. Riddle, M. L. Crawford, and R. T. Johnk, "Aperture excitation of electrically large, lossy cavities," IEEE Transactions on Electromagnetic Compatibility, Vol. 36, No. 3, 169-178, 1994. doi:10.1109/15.305461
14. Arnaut, L. R., "Measurement uncertainty in reverberation chambers,", Report TEQ 2, Ed, 2.0, National Physical Laboratory (UK), 2008.
15. IEC 61000-4-21, "Electromagnetic compatibility (EMC) - Part 4-21: Testing and measurement techniques - Reverberation chamber test methods,", International Electromagnetic Commission (IEC), 2011.