Investigation on the use of metamaterials to lower the operating frequency of reverberation chamber

An investigation on the use of metamaterials as walls for the reverberation chamber (RC) to lower its lowest usable frequency (LUF) is presented in this paper. The method used to lower the resonant frequencies is based on the concept of subwavelength cavities. The resonant frequencies of a metamaterial wall 3D cavity are derived and expressed analytically in terms of macroscopic characteristics. Analytical design guidelines are then given to choose the required microscopic parameters for the metamaterials to realize the subwavelength 3D cavity. Our results are in agreement with numerical simulations. The mode density achieved in such subwavelength RCs are then studied using an numerical eigen solver. Compared to traditional RCs, a higher modal density is obtained at low frequencies. The cumulative density function of the numerically calculated electric field in a metamaterial wall RC is finally compared to that of a metallic wall RC for an equivalent modal density to highlight the decrease in frequency which can be achieved using this approach.