Comparison of methods for determining the number of independent stirrer positions in reverberation chambers

A method for estimating the number of independent stirrer positions in reverberation chambers is described in IEC 61000-4-21 [5]. This standard method is known to have disadvantages that have been discussed e.g. in [7] and [10], but it is a practical way to estimate the number of independent stirrer positions with comparatively low effort. Beside this standard method there are different alternatives methods that have been proposed in the past. An overview is given in [11]. Both the standard method as well as the alternative methods yield an estimation only which means that a reasonable evaluation or comparison of the methods could not be given so far. A general method for determining the number of independent stirrer positions in reverberation chambers was presented in [10] together with a first evaluation of the standard method. It was shown that the general method yields detailed information about the number and distribution of the independent stirrer positions and was therefore deemed to be particularly suitable to evaluate other methods. This is where the following paper ties in. It provides a more detailed evaluation of the standard method and selected alternative methods based on the results from the general method.