Browsing by Author "Omollo, Nancy A."
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- ItemShielding effectiveness investigations using a reverberation chamber(Stellenbosch : Stellenbosch University, 2019-04) Omollo, Nancy A.; Wiid, P. G.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Electromagnetic interference (EMI) is one of the most common problems encountered in radio astronomy observatories. Interaction of electromagnetic (EM) waves from different sources may result in device malfunction due to misinterpretation of the transferred data or information loss. Most equipment and facilities at a radio astronomy observatory are sensitive to this interference. It is therefore important to find a solution to protect these sensitive instruments from damage that may result due to EMI. Many steps have been taken to provide these solutions, including radio frequency campaigns, careful design of electronic systems, radio frequency propagation investigations and shielding. In the latter case, there have been several materials that have been used in shielding at different levels. However, most of the commonly used materials are costly. This project characterizes alternative affordable commercial materials that can be used for shielding. Characterization of these materials is done using a reverberation chamber and specific to the nested reverberation chamber technique for repeatability purposes. The measurements are done in frequency domain (FD) and validated using time domain (TD) methods. The two sets of measurements are carried out in two different reverberation chambers with different physical dimensions and characteristics. The TD measurement is investigated for measurement time speed-up. Measurement in TD is done using the real time analyser (RTA), which is a high dynamic range instrument with a measurement bandwidth of up to 3 GHz. A few of the investigated materials showed effective shielding. The absorbing sheet material and the radiant barrier roofing material showed shielding values of at least 30dB and above. These cheaper materials are therefore recommended for use at the Square Kilometre Array (SKA) buildings for additional shielding.