Correlation-Based Uncertainty in Loaded Reverberation Chambers

• Published in: IEEE transactions on antennas and propagation Vol. 66; no. 10; pp. 5453 - 5463
• Main Authors: Becker, Maria G., Frey, Michael, Streett, Sarah, Remley, Kate A., Horansky, Robert D., Senic, Damir
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna measurements; Antennas; Bandwidths; Correlation; electromagnetic measurements; Empirical analysis; Entropy; Loading; measurement correlation; measurement efficiency; Measurement uncertainty; Optimization; reverberation chamber; Reverberation chambers; Stirring; Uncertainty; Uncertainty analysis; wireless system
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2018.2860126

When reverberation chambers are loaded to increase the coherence bandwidth for modulated-signal measurements, a secondary effect is decreased spatial uniformity. We show that an appropriate choice of stirring sequence, consisting of a combination of mode-stirring mechanisms such as paddle and antenna-platform stirring, can mitigate the potential for increased uncertainty. We develop a new mode-stirring sample correlation model for uncertainty due to the stirring sequence. In a comparison with an empirical uncertainty analysis, the model is found to have an agreement within 2.5%. Our analysis is demonstrated for four loading cases in each of three reverberation chambers. The model is used to determine an optimal stirring sequence for a given chamber setup directly from correlations associated with each stirring mechanism. The model can also be understood in terms of the entropy of a measurement and it is shown that maximizing the entropy corresponds to a minimized uncertainty. The method presented here not only provides insight into sources of uncertainty but also allows users to determine an optimal mode-stirring sequence with minimized uncertainty for a given chamber setup.