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An investigation of coupling mechanisms in narrowband microwave filters

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2008. / The design of an aperture-coupled coaxial diplexer for R-band, is presented. To
improve the ease of tuning, a tuning procedure for the diplexer with the aid
of a MATLAB application with graphical user interface, is developed. Final
experimental results show good agreement between the circuit model and the
physical structure. Final measurements of the diplexer structure achieved 18.83 dB
and 21.52 dB return loss in the lower and upper frequency band respectively and
insertion loss of 0.58 dB and 0.61 dB was measured for the two frequency bands.
Isolation were measured as 74 dB at 2.01 GHz and 84 dB at 2.17 GHz
The accuracy of two techniques for determining coupling coefficients in coaxial
and waveguide resonators are investigated. One method is the Eigenmode Method
for determining the coupling coefficients in a physical resonator and the other the
circuit model representation, utilising inverters to represent the coupling between
resonators. Results showed that marked differences occur when using the three
different inverter configurations to enable filter dimensioning for a given coupling
coefficient.
Four waveguide filters, utilising posts and irises respectively, are designed using
dimensions obtained from the three inverter configurations as well as the Eigenmode
method for a certain coupling coefficient.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2496
Date03 1900
CreatorsHansmann, Esti Mari
ContributorsMeyer, P., University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
PublisherStellenbosch : University of Stellenbosch
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeThesis
RightsUniversity of Stellenbosch

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