Loaded transmission lines illuminated above ground

Stuart, Thomas (1999-12)

Thesis (M.Sc.Ing) -- University of Stellenbosch, 1999.


ENGLISH ABSTRACT: This thesis provides a solution to an EMC problem that arose from an open cast mining system, which suffered from premature detonation. The industry problem is treated as a generic wiring problem, where a transmission line above a ground is illuminated by a plane wave noise source. By choosing appropriate transmission line termination loads, a minimum in the noise power at one termination is sought. Systematic variation of the loads is carried out above both and ideal and a lossy ground. Simulations are performed using NEC4D, which is a well established wire-based method-of-moments frequency-domain code, and MTL_SIM, which is a one-dimensional finite-difference time-domain code. A careful measurement above each type of ground is performed to confirm the accuracy of the measurements. In order to perform a measurement above lossy ground an artificial dielectric with electrical characteristics similar to soil is used. The electrical characteristics of the artificial soil are measured using a stripline system that was developed for that purpose. It was found that by choosing suitable loads the noise power can be considerably reduced. This is a low cost solution to the problem, and is easy to accomplish. At the same time the ability to measure and simulate this type of problem is developed.

AFRIKAANSE OPSOMMING: Hierdie tesis bied 'n oplossing vir 'n EMV probleem wat by 'n oopgroef myn ontstaan het. Ongewenste detonasies is veroorsaak deur onverwagte platvlakgolf straling. Hierdie probleem word as 'n bedraadingsisteem, waar 'n belaste transmissielyn onder die invloed van platvlakgolfstraling verkeer, behandel. Die transmissielyn terminasies word sistematies bokant beide ideale en nie-ideale grondvlakke gevarieer, en die ruisdrywing in die terminasies gemeet. Simulasies is met NEC4D, 'n Momentmetode frekwesiegebiedkode, en MTL_SIM, 'n eendimensionele eindige element tydgebiedkode, uitgevoer. Die akuraatheid van die simulasies word getoets teen resultate van 'n sorgvuldige meetproses. As nie-ideale grondvlak is 'n dielektriese medium met elektriese eienskappe soortgelyk aan die van ware grond gebruik. 'n Strooklyn meetopstelling is ontwerp om die elektriese eienskappe van die dielektrikum te meet. Resultate van simulasies en metings to on duidelik dat die korrekte keuse van transmissielyn terminasies is minimum ruisdrywing in die terminasies tot gevolg kan he. Sodoende word 'n laekoste oplossing vir die spesifieke probleem daargestel terwyl insig in die oplossing van die soort EMV -probleme in die algemeen verkry word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/51324
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