Coupled-mode theory for RF and microwave resonators

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dc.contributor.advisorTervo, Richard
dc.contributor.advisorMattar, Saba
dc.contributor.authorElnaggar, Sameh
dc.date.accessioned2023-03-01T16:32:32Z
dc.date.available2023-03-01T16:32:32Z
dc.date.issued2013
dc.date.updated2016-10-24T00:00:00Z
dc.description.abstractThe case of two dielectric resonators inserted in a cavity is fully analyzed. It is shown that the three uncoupled modes interact to form three coupled ones. Accordingly, Energy Coupled-Mode Theory, a coupled mode formalism where energy is conserved, is developed to study the coupling of RF and microwave resonators. The governing equations are written in the form of an eigenvalue problem where the eigenvalues represent the square of the frequencies and the eigenvectors are the fields’ coefficients. Both external and internal boundary conditions are discussed. The coupled mode formalism is capable of analyzing a system consisting of an arbitrary number of resonators. Using the proposed equations, the physical origin of the coupling coefficient is found and interpreted based on the energy conservation principle. The interpretation is general and universal and is believed to encompass cases where dielectrics and conductors are present. An important electron paramagnetic resonance probe, namely a cavity with a tiny insert, is studied. It is shown that when the frequency of the cavity is equal to that of the insert, the resulting fields are complete mixes of the two uncoupled modes. This finding, together with others, finds applications in the magnetic resonance and dielectric measurements fields. Different practical scenarios (large/small cavities, high/moderate relative permittivity values) are discussed in detail. Expressions for field dependent parameters such as coupling coefficients, Q values, filling factors and resonator efficiency are derived. It is shown how these parameters contribute to the probe performance and how, in some circumstances, trade-offs need to be made. Design procedures for electron paramagnetic resonance probes, verified using finite-element simulations, are proposed. It is found that proper design can indeed enhance the electron paramagnetic resonance signal. Particularly, the shield can help in boosting the resonator efficiency of a lossy dielectric resonator. The method of images, area commonly used electromagnetic technique, is used together with the coupled mode theory to study cases where resonators are placed close to conducting planes. The aforementioned situations occur in the field of magnetic resonance spectroscopy when dielectric resonators are used as tuners. These situations also exist when conducting planes are used to enhance wireless power transfer using resonant inductive coupling.
dc.description.copyright© Sameh A. Elnaggar, 2013
dc.description.noteElectronic Only. (UNB thesis number) Thesis 9264. (OCoLC) 961106541.
dc.description.notePh.D., University of New Brunswick, Department of Electrical and Computer Engineering, 2013.
dc.formattext/xml
dc.format.extentxxii, 253 pages
dc.format.mediumelectronic
dc.identifier.oclc(OCoLC) 961106541
dc.identifier.otherThesis 9264.
dc.identifier.urihttps://unbscholar.lib.unb.ca/handle/1882/14068
dc.language.isoen_CA
dc.publisherUniversity of New Brunswick
dc.rightshttp://purl.org/coar/access_right/c_abf2
dc.subject.disciplineElectrical and Computer Engineering
dc.subject.lcshDielectric resonators.
dc.subject.lcshCoupled mode theory.
dc.subject.lcshElectron paramagnetic resonance.
dc.titleCoupled-mode theory for RF and microwave resonators
dc.typedoctoral thesis
thesis.degree.disciplineElectrical and Computer Engineering
thesis.degree.fullnameDoctor of Philosophy
thesis.degree.grantorUniversity of New Brunswick
thesis.degree.leveldoctoral
thesis.degree.namePh.D.

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