A novel method to examine the effectiveness of a stirrer

In a reverberation chamber, the internal electromagnetic fields are perturbed by a metallic stirrer and thus the stirrer has a significant impact on the chamber performance. How to judge the effectiveness of a stirrer has been a question for years, in this paper, we propose a novel method, based on the principle of eigenmodes perturbation, to examine the effectiveness of a stirrer. Comparing three types of stirrers, we find that a stirrer with bending and in an irregular shape is the most effective, and it has the ability to shift the eigenfrequencies of the chamber most significantly. A new approach to examine the stirrer effectiveness is performed by using spherical chambers. Analysis of the field uniformity in a practical rectangular chamber is conducted to justify the approach