Practical Correlation-Matrix Approaches for Standardized Testing of Wireless Devices in Reverberation Chambers

Abstract

We extend the autocorrelation-based approaches currently used in standards to full correlation-matrix-based approaches in order to identify correlation between both spatially adjacent and non-adjacent samples in reverberation-chamber measurements. We employ a scalar metric that allows users to identify the number of effectively uncorrelated samples in new types of stirring sequences. To make these approaches practical and enhance their accuracy, we implement a thresholding technique that retains correlation related to important aspects of chamber configuration such as loading and undermoded conditions. We develop a method to propagate uncertainty in the complex correlation coefficients through to the number of effective samples for a given reverberation-chamber set-up by use of a bootstrap technique that is accurate even for highly skewed distributions of correlation coefficients. We further apply this method in a sensitivity study regarding the choice of threshold value. Agreement with existing approaches in determining the number of effectively uncorrelated samples is presented for a measurement example where spatially adjacent samples are utilized. Examples are then illustrated for non-spatially-adjacent correlated samples at microwave and millimeter-wave frequencies.