Beginning of September, Ludivine Le Bars, SIEPEL PhD student presented a paper regarding chaotic reverberation chambers at EMC Europe in Barcelona;

SIEPEL R&D department have worked on the geometry and loading impact inside a reverberation chamber (RC) on different statistical and normative criteria. The purpose was to overcome the challenge of reaching the standard criteria at low frequencies for a small RC.

These tests were performed in three different RCs in France: at the IETR (Rennes) where the lowest usable frequency (LUF) of the RC room is 200 MHz, at the ESYCOM laboratory (Paris) and at SIEPEL factory where the LUF of both cavities is 400 MHz. We drew the same conclusions for all three RCs.

In order to study the geometry of the RC, we made it chaotic by introducing spherical metallic caps on the walls. We noticed an improvement of the performances compared to a classical RC. However, we observed that the normative criterion is less sensitive than the statistical one.

In addition, we questioned ourselves about how to improve the performances of the RCs. Were they supposed to be related to the geometry or to the load added by the spherical caps?

To understand this phenomenon, we worked with a constant quality factor by replacing the spherical caps with absorbers.

Final results have shown that the results between an identical cavity with and without spherical caps were close to each other but with equivalent losses. Indeed, on the one hand, the main effect observed is absorption; on the other hand, the RC seems to be already chaotic without the addition of spherical caps.