An investigation of radiated EMI induced in wire-connected electronic systems : numerical modelling and experimental measurements

Date
1996
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: In this thesis the coupling of radiated energy into transmission lines is investigated for electromagnetic compatibility (EMC) purposes. This was done with NEC (Numerical Electromagnetics Code), a widely used moment method code for numerical modelling of the electromagnetic behaviour of wire systems. In the investigation an LPDA (log periodic dipole array) was used to illuminate transmission lines above a ground plane and the resulting coupling to a resistive load at the end of each transmission line was determined. NEC was used to predict this coupling. To check the accuracy of the predictions, careful measurements were performed with a network analyser. The LPDA antennas which were used for the measurements had to be extensively modified at the feed point to ensure that they were properly fed in the diferential mode. An infinite balun (balanced to unbalanced transformer) technique was used and the implementation therof is presented. The transmission line also needed balancing. The balun employed for this purpose and a way to remove its effect on measured data are described. EMC, EMC requirements and the bodies responsibilities for creating and enforcing the EMC standards are also discussed.
AFRIKAANSE OPSOMMING: In hierdie tesis word die koppeling van gestraalde energie na transmissielyne, uit 'n elektromagnetiese aanpasbaarheids oogpunt, ondersoek. Dit word gedoen met NEC (Numerical Electromagnetic Code), 'n algemeen gebruikte moment metode program wat die elektromagnetiese gedrag van draad stelsels numeries modelleer. In die ondersoek word 'n LPDA (log periodic dipole array) gebruik om 'n transmissielyn te belig en die koppeling, na ;n resistiewe las aan die einde van die lyn, word met NEC bepaal. Versigtige metings word met 'n netwerk analiseerder gedoen om die akkuraatheid van die NEC voorspellings te evalueer. Die LPDA antenna wat vir die metings gebruik is, moes baie by die voerpunt verander word. Dit was nodig sodat die antenna in 'n suiwer differensiële modus gevoer kon word. 'n Oneindige balon (balans na onbalans transformator) is hiervoor gebruik en 'n manier om dit te implementeer word bespreek. Die transmissielyn moes ook gebalanseerd gemeet word en die balon wat daarvoor gebruik is, asook die resultate wat daaruit spruit, word bespreek. Elektromagnetiese aanpasbaarheid (EMA), EMA verseistes, die liggame wat EMA standaarde opstel and die liggame wat die standaarde afdwin, word ook bespreek.
Description
Thesis (MEng)--University of Stellenbosch, 1996.
Keywords
Electromagnetic interference -- Data processing, Electric lines -- Data processing, Signal integrity (Electronics), Electromagnetic measurements
Citation