Paper on PCB absorption cross-section measurements in reverberation chamber

Paper on measured average absorption cross-section of printed circuit boards (PCBs) accepted for publication in IEEE Transaction on Electromagnetic Compatibility.

Absorption by the contents of an equipment enclosure, particularly PCBs, affect the enclosure’s shielding performance. At high frequencies we propose that this absorption can be quantified using the angle of arrival and polarization averaged absorption cross-section (ACS), which can be measured in a reverberation chamber. This paper presents the measured average ACS of a large number of PCBs taken from contemporary information and communication technology (ICT) equipment to provide a unique and comprehensive dataset for developing high frequency shielding methodologies.

The images above show a photograph of one PCB from each of the classes of PCB identified and the measured average ACS of the all the PCBs coloured according to their class.

This work was part of the collaborative shielding measurement of electrically large enclosures with contents project between Huawei Technologies and the AEG. See the paper (Flintoft et al., 2016) for details.

References

1. Flintoft, I.D., Parker, S.L., Bale, S.J., Marvin, A.C., Dawson, J.F. and Robinson, M.P., 2016. Measured average absorption cross-sections of printed circuit boards from 2 to 20 GHz. IEEE Transactions on Electromagnetic Compatibility, 58(2), pp.553–560.
   

   Absorption by the contents of an equipment enclosure, particularly printed circuit boards (PCBs), affect the enclosure’s shielding performance. At high frequencies, this absorption can be quantified using the angle of arrival and polarization averaged absorption cross-section (ACS). However, there is no available data on the high-frequency absorption characteristics of modern PCBs. In this study, we apply a reverberation chamber to the determination of the average ACS of a large number of PCBs taken from contemporary information and communication technology (ICT) equipment to provide a unique and comprehensive dataset. The ACS was found to range from 4 × 10-4-10-2 m2 from 2-20 GHz and different classes of PCB could be identified according to their surface characteristics. The “shadowing effect” of densely packed PCBs was also quantified for a subset of the PCBs. It was found that the ACS of a PCB in the stack was reduced by 20%-40% compared to its value when isolated. By way of a review of the general power balance analysis of an electrically large populated equipment enclosure in an external environment, we show how the acquired data will be useful for future qualification methodologies for ICT enclosures and PCBs.

   @article{Flintoft2016a,
     author = {Flintoft, I. D. and Parker, S. L. and Bale, S. J. and Marvin, A. C. and Dawson, J. F. and Robinson, M. P.},
     title = {Measured average absorption cross-sections of printed circuit boards from 2 to 20 GHz},
     journal = {IEEE Transactions on Electromagnetic Compatibility},
     year = {2016},
     volume = {58},
     number = {2},
     pages = {553-560},
     month = apr,
     issn = {0018-9375},
     note = {Date of acceptance: 29/12/2015. © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.},
     doi = {10.1109/TEMC.2016.2515658},
     file = {:pdfs/TEMC58-Flintoft-553.pdf:PDF},
     keywords = {shielding, printed circuit board, absorption cross-section, reverberation chamber, immunity, emissions, power balance},
     postprint = {https://pure.york.ac.uk/portal/files/46384073/TEMC58_Flintoft_et_al_553_postprint.pdf},
     publisher = {IEEE}
   }