Average Number of Significant Modes Excited in a Mode-Stirred Reverberation Chamber

Although the number of significant modes is intuitive, this concept has never been clearly defined, mainly because of the unbound number of modes involved in modal overlap. In the present paper, we show that, for a perfect stirring process, the effect of modal overlap can be modeled as an equivalent filtering formulation. By introducing the statistical-bandwidth concept, we show that the electromagnetic field statistics due to an infinite number of modes can be summarized by a finite number of significant modes. The case of the electric-energy density in an mode-stirred reverberation chamber has been considered and a new expression of its variability has been established. The good agreement found between the new expression and the experimental and simulation results support the several concepts introduced in this paper.