How to Avoid Unstirred High Frequency Components in Mode Stirred Reverberation Chambers

The Role of Losses in the Definition of the Overmoded Condition for Reverberation Chambers and Their Statistics

“…A similar conclusion was also suggested in a study based on a canonical modal representation [16], though the lack of an analytic approach hindered the development of predictive/design tools; moreover, the possibility of non-compliancy above the LUF was not pointed out. Indeed in [14], [15], no doubt could subsist about the stirrer efficiency at those frequencies where the field statistics was shown not to comply with the asymptotic probability laws predicted by continuous plane-wave spectrum models, especially because they occurred over a small subset of scattered frequencies.…”

“…Under these conditions, experimental data have been presented in [12], [13], [14], [15], providing clear clues that the overmoded condition is actually not based on a threshold level for the modal density and that losses can have a beneficial impact on field statistics [12], [13]. A similar conclusion was also suggested in a study based on a canonical modal representation [16], though the lack of an analytic approach hindered the development of predictive/design tools; moreover, the possibility of non-compliancy above the LUF was not pointed out.…”

The reverberation chamber's unstirred field: A validation of the image theory interpretation

“…Thus, the effectiveness of using directional antennas strongly depends on how these antennas and the corresponding "source" antenna images are oriented with respect to one another. As suggested in [15], the effectiveness of directional antennas may be improved by pointing their main beams toward the stirrers. From our image-blocking model, we see that this will effectively shunt power from the unobstructed ray paths to those blocked by the stirrers.…”

A statistics-based definition of the overmoded condition for reverberation chambers

“…Although such type of model well approximates the behavior of real-life RCs in their high-frequency range, it is well-known that there might exist some frequencies where it is incapable of predicting a drift from it [6]. These disagreements are often explained through a stirrer inefficiency or a sub-optimal alignment for the sources [7], though we are quite skeptical of these explanations [8], whereas in the lower frequency range they are usually just fitted to alternative probability distribution functions [9].…”