A test system for free-field qualification of anechoic chambers

Qualification of anechoic and hemi-anechoic chambers is intended to demonstrate that a chamber adequately supports free-field conditions for a given test sample. However, the common practice of measuring widely spaced points along a traverse line is an inadequate measure of inverse square law performance, particularly for frequencies at and above 1000 Hz. On the other hand, continuous traverses yield a more complete picture of the capabilities and limitations of an anechoic space. A new qualification measurement system has been developed at Georgia Tech to allow for easily repeatable, automated continuous traverse measurements. The highly portable system makes use of Labview and MATLAB tools to perform, control and analyze a complete traverse test, giving real-time access to the data and immediate processing and analysis of the results. This article will describe the new system, present data taken for an anechoic chamber and demonstrate the benefits of this system over current methods.