Browsing by Author "Bester, Alo-Helene"
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- ItemCharacterisation of the anechoic chamber at Stellenbosch University(Stellenbosch : Stellenbosch University, 2019-12) Bester, Alo-Helene; Meyer, Petrie; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The anechoic chamber at the University of Stellenbosch is used on a weekly basis to measure and characterise antenna radiation patterns. Although excellent comparisons between measurements and simulations are achieved, the chamber itself was never characterised to establish how accurate measurements are and how large the contribution of errors is to the measurement uncertainty. The aim of this thesis is to characterise the chamber to an industry standard. The NIST 18 term error analysis was used for this evaluation. The analysis makes use of statistical analytical methods, measurements, simulations, as well as mathematical calculations to establish the measurement uncertainties. Errors that form part of the chamber environment and setup can influence different sections of the radiation pattern. It can either affect the radiation pattern main lobe or the sidelobes or both. During the investigation, it was determined how significant the influence of the various errors are on the different sections of the radiation pattern and how large the associated uncertainty are. A spin-off from the study was that a mechanical calibration of the chamber setup was done and a complete guide to the calibration process is included in this document.