Maple algorithm for damping quality of anechoic chambers evaluation

Abstract

Anechoic and semi anechoic chambers are among the necessary equipment that is needed for testing of devices for their electromagnetic compatibility or for experiments with electromagnetic field emitters, receivers, shielding and many more devices. As they require shielding for their proper operation, undesirable reflections occurring inside them are a natural consequence that must be eliminated by suitable absorbers. Naturally, the reflections cannot be eliminated absolutely in any case, but the aim of the constructers of such chambers is always to minimize them as well as possible. As the constructions of the chambers differ, each of them shows different resonant frequencies and standing waves displacement, although it complies with the standards for electromagnetic compatibility measurement. This phenomenon increases in its importance when the chamber is intended to be used for scientific purposes. In some cases, the knowledge of its behavior is crucial for various experiments. Because the standing waves caused by the reflections inside the chamber manifest themselves as resonant peaks occurring in the frequency response measurement, one of the possibility of evaluation of the quality of the reflections’ damping is to identify the resonant peaks and calculate the Q-factor of the chamber, considering it acts as a cavity resonator. As cavity resonators usually show very high Qfactors, the lower value is obtained, the better damping by the absorbers in the chamber is ensured. One of such approaches to evaluate the real chamber that is being operated at Tomas Bata University in Zlin, using an algorithm implemented in Maple software, is described within the framework of this paper. © 2016, North Atlantic University Union. All rights reserved.