Passive field uniformity enhancement in reverberation chambers

Abstract

Much has been written on field uniformity enhancement and different types of stirrers for reverberation chambers. We have distilled the theory and applied this to a full-wave electromagnetic simulation of an empty, rectangular cavity with and without the introduction of shaped conductive structures. In anticipation of real-life applications, both dipole and Yagi-Uda antennas, orientated in the vertical and horizontal, were used as radiators. This study presents attempts to passively distribute the fields more evenly inside a reverberation chamber by supporting more modes with the introduction of conductive structures inside the chamber. A brief theoretical background is given to support the simulation-based analysis reported here. Simulations were conducted for a 1.86 × 2.44 × 2.47 m screened room. The results show that passive field enhancement has improved the standard deviation when compared to an empty chamber. The simulated standard deviation of the internal total electric field distribution over a frequency band of 1 - 2 GHz shows marginal improvement in the field uniformity of between 0.6 dB at lower frequencies and 0.1 dB at higher frequencies when introducing static conductive structures in the cavity and employing a horizontally positioned dipole. However, passive “stirring” of the modes alone does not satisfy the requirements for electromagnetic compatibility testing using reverberation chambers, but it does pose an improvement in the performance of reverberation chambers where dynamic mixing of the modes is done through rotating stirrer structures.