Analytical Expressions for Uncertainties in Measured Reverberation Chamber Field Strengths

Abstract

Analytical expressions for uncertainties introduced into reverberation chamber field intensity measurements due to imperfect knowledge of the mean field level are derived. Expressions for the normalized root-mean-square error in estimates of the mean field level show that the maximum-likelihood estimation approach is superior to direct averaging of field samples, independent of the number of samples used in the estimate. The probability distribution functions of the ratio of test-field-sample to estimated-mean are then derived, both for the case where the test sample is an additional independent measurement and when the test sample was used in performing the mean estimation. The distributions give a direct representation of the effects mean field level uncertainty on the sample-to-mean ratio statistics. The expressions are general for both one-axis and three-axis field-intensity measurements.