Analysis of the Independent Positions of Reverberation Chamber Stirrers as a Function of Their Operating Conditions

The independent positions of the stirrers are computed when one or two stirrers rotate inside the chamber. In the case of the two operating stirrers, they are moved in both tuned and stirring modes. In the tuned mode, they are rotated in a synchronized or interleaved way, showing that this second modality yields a larger independent position number. In the stirring mode, both modalities are replicated varying the rotation speed. In the case of one stirrer and two synchronized stirrers, the independent positions are computed using the classical autocorrelation function, whereas in the case of two completely independent stirrers a 2-D autocorrelation is proposed. The result obtained in this second way does not depend on the order chosen to move the stirrers. The performance of the stirrers is also verified checking the ratio between the maximum and the average received power inside the chamber, the statistics of the received power by applying a goodness-of-fit test, and the uniformity of the field in some points of the working volume. Tuned and stirring operating modalities are also compared in terms of measurement time, calibration and software complexity, motor stress, and so on.