Shielding effectiveness in a two-dimensional reverberation chamber using finite-element techniques

A reverberation chamber is an enclosure consisting of metal walls with a metallic paddle wheel (denoted as a "stirrer" or "tuner") forming a high quality-factor (Q) cavity with continuously variable boundary conditions. Reverberation chambers are attaining an increased importance in determining the electromagnetic susceptibility of avionics equipment. Given the nature of the variable boundary condition, the ability of a given source to couple energy into certain modes and the passband characteristic due the chamber Q, the fields are typically characterized by statistical means. The emphasis of this work is to apply finite-element techniques at cutoff to the analysis of a two-dimensional structure to examine the notion of shielding-effectiveness issues in a reverberating environment. Simulated mechanical stirring is used to obtain the appropriate statistical field distribution. The shielding effectiveness (SE) in a simulated reverberating environment is compared to measurements in a reverberation chamber. A log-normal distribution for the SE is observed with implications for system designers. The work is intended to provide further refinement in the consideration of SE in a complex electromagnetic environment.