Intelligent Representation Of Semi-Anechoic Chamber Wall Cuts Electromagnetic Simulation Time 95%

Electromagnetic simulation of semi-anechoic chambers is a very difficult task. A very fine mesh is normally required in the wall area to model the performance of absorbers that are used to make the chamber act as if it were an Open Area Test Site (OATS). The fineness of the mesh typically results in very long simulation times, such as the 15 weeks that could be needed on a desktop computer in the past to model chambers to evaluate the effect of the qualification antennas. Simulation is critical in the design process to capture the near-field effects in the 30 to 200 MHz frequency range which cannot be determined by theoretical methods.

Gwenaël Dun, R&D Engineer for Siepel, used a variety of different electromagnetic simulation tools to address this challenge in the past but ran into problems with both poor accuracy and long compute times. He then worked with Flomerics, the developer of MicroStripes electromagnetic simulation software, to implement a feature that makes it possible to model the ferrite absorbers used in the chamber as a boundary condition rather than part of the computational domain. This change made it possible to increase mesh size by a factor of 15, reducing compute time by 95%. The simulation results provided a near-perfect match to physical testing.