Conference Agenda

This paper investigates the statistical characterization of complex electromagnetic environments (EMEs), which often resemble "good but imperfect" reverberation chambers (RCs). Traditional RC models typically assume ideal reverberant conditions, leading to discrepancies when applied to real-world EME field distributions. Inspired by the analogy between these EMEs and "good but imperfect" RCs, we assess the performance of various statistical models from the literature that aim to characterize the field distribution within these complex EMEs. The statistical models examined and compared are derived from wireless communication systems and RC theory. We utilized electric field measurement data from two buildings with different wall materials—steel and sheetrock/aluminum—with ultra-wideband measurements ranging from 2 to 8 GHz. This research highlights the limitations of traditional ideal RC models while demonstrating the promise of a proposed bivariate approach for “good but imperfect” RC, providing a more accurate and physically interpretable characterization of complex EMEs. The findings of this study contribute to the advancement of methods for characterizing complex EMEs, potentially improving the design and testing of electronic systems for electromagnetic compatibility.

In reverberation chamber studies, time series have been used to model field correlations induced by stirring processes. Traditionally, linear time series (LTS) models were applied even for rotating stirrers, despite their limitations. Recent work [1] introduced a circular time series (CTS) model that more accurately captures the behavior of rotating stirrers. This paper extends the CTS model by deriving its associated probability density function (PDF) and presents a revised PDF expression better suited for linear stirrers. The revised PDF significantly improves upon models commonly used in the electromagnetic compatibility (EMC) community. By deriving the lag-1 correlation coefficient PDF for both rotating and linear stirrers, this work provides more appropriate statistical descriptions of stirring-induced correlations. The proposed framework enhances the accuracy and applicability of time-series models in reverberation chamber studies, and the theoretical results are validated through experimental measurements.

In this study, the variation of resonant frequencies in a vibrating intrinsic reverberation chamber (VIRC) is investigated as a metric for evaluating mode-stirring strategies. A method is presented that correlates the variation of the first three resonant modes with changes in the geometric dimensions of a rectangular cavity. Therefore, undesired uneven directional changes in the boundary condition can easily be found, which can be used to further optimize the stirring strategy. These may remain undetected by use of conventional metrics due to the influence of positional stirring. Using this approach, practical measurements were performed to assess the impact of different stirring strategies on the efficiency of the mode-stirring process. A good correspondence with the theoretical predictions of the cavity resonator theory was observed. It was found that the variation of resonant frequencies can be used to predict stirring performance in the overmoded regime, where conventional methods based on field uniformity are commonly employed. The results demonstrate that an effective stirring strategy should involve dimensional changes in all spatial directions. Additionally, experiments have shown that the insertion of a mechanical mode-stirrer moves the first resonance frequency of a cavity resonator downwards and thus influences the effective dimensions of the cavity.

Pulsed radiated susceptibility tests based on the measured absorption cross section ratio has been performed on a EUT within a reverberation chamber. The ACSR is used to identify frequencies where the absorption of the EUT is high. Whether the ratios of the ASCR together with a single susceptibility level can be used to infer the EUT’s behaviour over a wider frequency band or not is investigated.