Low frequency modeling for electromagnetic analysis of arbitrary anechoic chambers

An efficient and accurate method is presented to compensate for the lack of fast methods in anechoic chamber modeling at low frequencies (from 30 to 300 MHz). In this method, surface equivalence principle is applied to model the electromagnetic field scattering inside the chamber, and shooting and bouncing rays technique is utilized to establish the equivalent surface electric and magnetic currents. In order to improve the accuracy of ray tracing at lower frequencies, an approximate image theory for lossy dielectric surfaces is proposed to compute the reflection fields of absorbing materials. Simulations were compared with finite element method results to validate the formulation. Good agreement demonstrate the effectiveness of the porposed method.