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A Weibull distribution has been proposed for the probability density function (PDF) of the magnitude of the E-field in a reverberation chamber (RC). However, the Weibull distribution has two parameters, and if the parameters are position sensitive, the use of the Weibull distribution could be very limited. We investigate the sensitivity of the estimated parameters of the Weibull distribution in this study; the measurement results show that the parameters of the Weibull distribution depend on the positions of the antenna (or device under test), but not sensitive, and the statistical behavior of the parameters can be quantified. This means that the model of the Weibull distribution has a wider usable frequency range than that of the Rayleigh distribution and the statistical variation of the parameters needs to be considered.

Reverberation chambers (RCs) have been widely used in the electromagnetic compatibility (EMC) test and over-the-air (OTA) measurement [

The Weibull distribution has been verified at a specific antenna position [

To investigate this problem, we measure the

The Weibull distribution has been introduced to the RC in [

Thus, the Weibull distribution is more general than the Rayleigh distribution (or exponential distribution). By applying the MLE method, the estimated parameters

The random variable

(a) Schematic plot of the measurement. (b) Measurement scenario: the dimensions of the RC are 0.8 m × 1.2 m × 1.2 m; a plastic tube is used to support antenna 2. (c) Measurement positions of antenna 2 in the

The Weibull distribution parameters

Since the Weibull distribution has been verified in the undermoded region [

Estimated

To quantify the statistical behavior of the estimated parameters, the mean values and the relative standard deviations (RSDs) for different heights and polarizations are illustrated in Figure

Mean values and the relative standard deviation (in percentage) of the estimated

Mean values and the relative standard deviation (in percentage) of the estimated

To investigate the parameter stability of the Weibull distribution, we have adopted very fine measurements. 108 positions with three polarizations have been measured with 360 stirrer positions. The measurement results show that the parameters for the Weibull distribution are quite stable in the undermoded region and the statistical variation can be experimentally quantified.

Although the Weibull distribution model is valid in a wide frequency range, we have to note that the parameters have uncertainties. In the uncertainty analysis, we have to consider the uncertainties from two sources: (1) the estimated mean value (the FU definition in [

Calculated

We should note that although the Weibull distribution was found to be a good candidate to characterize the statistical behavior in the undermoded region, it may not be a unique one. There may exist other PDFs with more than two parameters to fit the undermoded region even better.

The data used to support this study are available from the corresponding author upon request.

The authors declare that there are no conflicts of interest regarding the publication of this paper.

This work was supported in part by the National Natural Science Foundation of China under Grant 61701224.