The work reported In this thesis is concerned with the fabrication and characterisation of microwave lumped element overlay capacitors for used at 10 GHz. The research has included the investigation and selection of suitable materials for use in the component manufacture, and,the development and optimisation of the necessary fabrication processes, which at the outset of' the project, were not available to the author. For this reason, and for the benefit of other research workers involved in the construction of microwave thin film components, the presentation of the processing data in this thesis is biased towards step-by-step accounts of' each of the major processes. The processing data is then readily available in a practical, and useful, form. Of' particular interest in the processing field, is the novel technique developed for the deposition of' the capacitor dielectric material without etching. This work was carried out in collaboration with a fellow research student, and is covered by a U.K. Patent. The microwave measurement of the capacitor properties have been performed using microstrip resonators. To enable these measurementsresonators to be accurately designed, measurements have been performed on, and results documented for, the transmission characteristics of microstrip lines on quartz substrates, and for the properties of micros trip gap discontinuities, and microstrip gap-and-step discontinuities, at X band. The technique for the measurement of the overlay capacitor properties is novel in that the capacitor is measured "in situ", and bond wires, which are a characteristic of' other measurement techniques, are not required. This permits a higher measurement accuracy, due to the reduction in connector parasitics. In addition, the equivalent circuit approach to the calculation of the capacitor properties is used, and not the perturbation approach, which permits large changes in frequency and Q factor during the course of the measurements, and this allows very measurements to be obtained. Results are presented for measurements performed on overlay capacitors, using silicon dioxide and alumina dielectric materials, and these indicate that capacitors with useful values of capacitance and Q factor can be produced at X band. Theories are presented for the capacitor electrode inductance and resistance, and these enable the dielectric constant and Q :factor of the capacitor dielectric materials, to be evaluated from the measured ccapacitor properties. Values of' the dielectric properties thus obtained are shown to be in good agreement with the characteristics of the dielectric materials in isolation, measured by a :fellow research student, using cavity techniques.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:465584 |
| Date | January 1974 |
| Creators | Michie, David |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/71389/ |
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