Interpolation-based modelling of microwave ring resonators

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dc.contributor.advisor Meyer, P. Schoeman, Marlize en_ZA
dc.contributor.other University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. 2008-07-28T13:52:51Z en_ZA 2010-06-01T08:13:12Z 2008-07-28T13:52:51Z en_ZA 2010-06-01T08:13:12Z 2006-12
dc.description Thesis (PhD (Electical and Electronic Engineering))--University of Stellenbosch, 2006.
dc.description.abstract Resonant frequencies and Q-factors of microwave ring resonators are predicted using interpolation- based modelling. A robust and efficient multivariate adaptive rational-multinomial combination interpolant is presented. The algorithm models multiple resonance frequencies of a microwave ring resonator simultaneously by solving an eigenmode problem. To ensure a feasible solution when using the Method of Moments, a frequency dependent scaling constant is applied to the output model. This, however, also induces a discontinuous solution space across the specific geometry and requires that the frequency dependence be addressed separately from other physical parameters. One-dimensional adaptive rational Vector Fitting is used to identify and classify resonance frequencies into modes. The geometrical parameter space then models the different mode frequencies using multivariate adaptive multinomial interpolation. The technique is illustrated and evaluated on both two- and three-dimensional input models. Statistical analysis results suggest that models are of a high accuracy even when some resonance frequencies are lost during the frequency identification procedure. A three-point rational interpolant function in the region of resonance is presented for the calculation of loaded quality factors. The technique utilises the already known interpolant coefficients of a Thiele-type continued fraction interpolant, modelling the S-parameter response of a resonator. By using only three of the interpolant coefficients at a time, the technique provides a direct fit and solution to the Q-factors without any additional computational electromagnetic effort. The modelling algorithm is tested and verified for both high- and low-Q resonators. The model is experimentally verified and comparative results to measurement predictions are shown. A disadvantage of the method is that the technique cannot be applied to noisy measurement data and that results become unreliable under low coupling conditions. en_ZA
dc.language.iso en en_ZA
dc.publisher Stellenbosch : University of Stellenbosch
dc.subject Adaptive interpolation-based modelling en_ZA
dc.subject Vector Fitting en_ZA
dc.subject Thiele-type continued fractions en_ZA
dc.subject Ring resonators en_ZA
dc.subject Resonant frequencies en_ZA
dc.subject Q-factors en_ZA
dc.subject Theses -- Electrical and electronic engineering en_ZA
dc.subject Dissertations -- Electrical and electronic engineering en_ZA
dc.subject.lcsh Microwave devices en_ZA
dc.subject.other Electrical and Electronic Engineering en_ZA
dc.title Interpolation-based modelling of microwave ring resonators en_ZA
dc.type Thesis
dc.rights.holder University of Stellenbosch
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