Numerical Characterization of Rodent Exposure Imbalances in Large Reverberation Chambers

In the past two decades, reverberation chambers (RCs) have been increasingly utilized in large-scale rodent bioassays to study dose-response relationships for cancer and non-cancer biological endpoints. Computational radio-frequency (RF) dosimetry plays a critical role in the design of these studies, influencing key parameters such as RC size, number, cohort size, and exposure frequencies. Given the complexity of modeling animal-loaded RCs, simplified random plane-wave (PW) superposition techniques have often been used, though full-wave characterizations have also been explored. This study expands previous research by analyzing the effects of line-of-sight (LoS) elimination in the Università Politecnica delle Marche RC at 900 MHz, modeling 96 caged rodents. Using whole-body Specific Absorption Rate (wbSAR) as the key observable, the study highlights asymmetries in RC exposures, showing higher wbSAR values near the mode-stirrer. The study investigates field diffusers and cage repositioning strategies to mitigate these imbalances. Simulations conducted with Transmission-Line Matrix (TLM) and Finite Element Method (FEM) techniques reveal a weaker correlation between wbSAR and rodent mass than previously reported. These findings suggest that real-world RC configurations introduce exposure variations not necessarily captured by idealized Rayleigh field models, impacting the interpretation of rodent bioassay results.