volume | PIER Journals

Abstract

Placing microwave absorbing materials into a high-quality factor resonant cavity may in general reduce the large interior electromagnetic fields excited under external illumination. In this paper, we aim to combine two analytical models we previously developed: 1) an unmatched formulation for frequencies below the slot resonance to model shielding effectiveness versus frequency; and 2) a perturbation model approach to estimate the quality factor of cavities in the presence of absorbers. The resulting model realizes a toolkit with which design guidelines of the absorber's properties and location can be optimized over a frequency band. Analytic predictions of shielding effectiveness for three transverse magnetic modes for various locations of the absorber placed on the inside cavity wall show good agreement with both full-wave simulations and experiments, and validate the proposed model. This analysis opens new avenues for specialized ways to mitigate harmful fields within cavities.

1. Robinson, M. P., et al. "Analytical formulation for the shielding effectiveness of enclosures with apertures," IEEE Transactions on Electromagnetic Compatibility, Vol. 40, No. 3, 240-248, 1998.
doi:10.1109/15.709422 Google Scholar

2. Nie, X.-C. and N. Yuan, "Accurate modeling of monopole antennas in shielded enclosures with apertures," Progress In Electromagnetics Research, Vol. 79, 251-262, 2008.
doi:10.2528/PIER07100403 Google Scholar

3. Eng Swee, S., et al. "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, 245-257, 2003.
doi:10.1109/TEMC.2003.810814 Google Scholar

4. Tait, G. B., et al. "On measuring shielding effectiveness of sparsely moded enclosures in a reverberation chamber," IEEE Transactions on Electromagnetic Compatibility, Vol. 55, No. 2, 231-240, 2013.
doi:10.1109/TEMC.2012.2220779 Google Scholar

5. Warne, L. K., et al. "A bound on electromagnetic penetration through a slot aperture with backing cavity," Sandia National Laboratories Report, 2016, SAND2016-9029, Albuquerque, NM, USA, 2016. Google Scholar

6. Campione, S., et al. "Preliminary survey on the effectiveness of an electromagnetic dampener to improve system shielding effectiveness," Sandia National Laboratories Report, 2018, SAND2018-10548, Albuquerque, NM, 2018. Google Scholar

7. Campione, S., et al. "Perturbation theory to model shielding effectiveness of cavities loaded with electromagnetic dampeners," Electronics Letters, Vol. 55, No. 11, 644-646, 2019.
doi:10.1049/el.2019.0656 Google Scholar

8. Campione, S., et al. "Penetration through slots in cylindrical cavities operating at fundamental cavity modes," IEEE Transactions on Electromagnetic Compatibility, doi: 10.1109/TEMC.2020.2977600, 2020. Google Scholar

9. Williams, D. F., "Damping of the resonant modes of a rectangular metal package [MMICs]," IEEE Transactions on Microwave Theory and Techniques, Vol. 37, No. 1, 253-256, 1989.
doi:10.1109/22.20046 Google Scholar

10. Dixon, P., "Cavity-resonance dampening," IEEE Microwave Magazine, Vol. 6, No. 2, 74-84, 2005.
doi:10.1109/MMW.2005.1491270 Google Scholar

11. Campione, S., et al. "Antenna loading impact on the coupling response of a slotted cylindrical cavity," Sandia National Laboratories Report, 2017, SAND2017-5378, Albuquerque, NM, 2017. Google Scholar

12. Harrington, R. F., Time-harmonic Electromagnetic Fields, Chapters 1, 5, 7, Wiley-IEEE Press, 2001.
doi:10.1109/9780470546710

13. ECCOSORB MCS, Emerson & Cuming Microwave Products, https://www.laird.com/rfmicrowave-absorbers-dielectrics/elastomers-films-foams/cavity-resonance-and-surface-wave-absorbers/eccosorb-mcs.
doi:10.1109/9780470546710

Dr. Salvatore Campione

Dr. Larry Kevin Warne

Dr. Isak C. Reines

Dr. Roy K. Gutierrez

Dr. Jeffery T. Williams