Evaluation of stirrer efficiency by means of first reflection

In mode stirred or reverberation chambers statistical electromagnetic measurements are undertaken. For the interpretation of the results it is important that the statistics in the chamber are correct. To ensure this the in most cases mechanical mode stirring must result in the desired field properties inside the chamber. The efficiency of mode stirring is usually decided by those field values. Thus, not the stirrer is evaluated, but the stirrer in connection with the chamber. This paper presents the basic idea of a new approach to rate the stirrer efficiency by its capability to interact with an incoming planar wave. The behaviour of the reflection determined in the far field is observed and ideas are presented on how to decide on the properties of those field values whether the stirrer is efficient or not. Taken into account is the distribution of the electromagnetic energy as well as its variation and the possible change in polarization comparing incoming and reflected waves.