Development and characterisation of an anechoic chamber

Abstract

This project explores the testing procedures in which the anechoic chamber, located on level 2 of the Faculty of Engineering and Surveying building at the University of Southern Queensland, can be characterised in the way of its performance regarding electromagnetic compatibilities. This characterisation will help further users of the anechoic chamber better understand the results in which are obtained within the chamber as well as know the interference that could be caused by the leakage of signals coming from the chamber. The performance characteristics that will be looked at are first of all the ability for the anechoic chamber to keep environmental noise from entering the chamber walls, creating false measurements, preventing harmful signals escaping and interfering with other commercial bandwidths. Then the pyramidal absorbers themselves will be analysed and their capability of attenuating a wide range of frequencies over a set number of angles of incidences will be recorded. This is the first step in a bigger task of being able to explain the patterns of variation in the electromagnetic field in a two dimensional plane. The way in which the performance of the pyramidal absorbers varies with angle helps explain this, as it gives the magnitude of absorption when a wave is reflected off the wall and interferes with the direct path, This process of following the different paths around the enclosed area is called ray tracing which is touched on in this project, but due to time constraints only the theory of the technique is recalled. From the results that were obtained, the anechoic chamber can now be utilised as to get a more accurate measurement by being able to configure the testing specifications to suit the chambers performance strengths and weaknesses. Even though some characterisation has been logged, there is still the potential for further work to be done to optimise the anechoic chambers useability and hopefully someday match the standards set for a commercial anechoic chamber.