A Novel Method for Accurately Predicting NSA Performance of Anechoic EMC Chambers

A novel method is presented to overcome the accuracy problem in the ray tracing method for anechoic EMC chamber modeling, with minimum increase in computing time and resources. The algorithm approximates absorber arrays as multi-layered flat structures through a homogenization technique. The chamber model is simplified by applying the homogenization to all the absorbers-lined walls within the chamber. The model simplification allows us to compute the first-order response of each absorber wall by utilizing the discrete complex image method (DCIM) for the layered media Green's function. In this study, we combine the complex images with the higher order reflections (wall-to-wall reflections) from the ray tracing method to obtain the full responses. A simulation tool based on the presented algorithm has been developed for EMC chamber designs, including both full-anechoic chambers and semi-anechoic chambers. The tool has the ability to model anechoic chambers at low frequencies down to 30 MHz, meanwhile, retaining the efficiency of the ray tracing technique. Comparison against full-wave simulations and measurements demonstrates its excellent accuracy and efficiency.