Fast and Accurate Assessment of the “Well Stirred Condition” of a Reverberation Chamber From $S_{11}$ Measurements

This paper presents a method to determine the frequency where a reverberation chamber starts to be “well stirred” according to the number of stirring conditions (i.e., different positions of a mode stirrer for a mechanically stirred chamber) considered. The method, based on S
₁₁
measurements of an antenna inserted in the reverberation chamber to be characterized, requires a simple measurement setup, is fast (few minutes) while leading to an excellent level of accuracy (maximum uncertainty of 10%) as demonstrated by the measurement results shown in this paper. The method takes advantage of a reliable definition of the well stirred condition leading to threshold values theoretically justified. Clear measurement guidelines and recommendations on the post-treatment process (available on demand) are also given. The method, proposed to the community of users as an alternative calibration procedure, provides reliable information on the chamber performances in the “grey zone” between the lowest usable frequency defined by standards and the frequency when the chamber is actually well stirred.