Abstract
Modem fabrication processes offer the microwave and millimetre-wave circuit designers a wide range of techniques and materials for realising planar circuits. Consequently, an in-depth analysis of the materials properties and their influence on particular planar design is needed to support the design process. The outcome of the research described in this thesis provides microwave and millimetre circuit designers with information on microwave performance of thick film conductors on 96% alumina substrates. Design procedures for single layer and multilayer edge-coupled bandpass filters (ECBPFs) are developed and validated through practical measurements. These filter circuits were fabricated using photoimageable thick film technology at different frequencies. The influence of the fabrication process on the performance of single layer and multilayer ECBPFs circuits has been investigated. The measured results of multilayer ECBPFs are compared with those from conventional single layer circuits. The results have shown that the filters in multilayer structure can overcome the limitation of the conventional single layer components. The outcomes of the research work showed the performance benefits that accrue from the use of multilayer circuits, in terms of a significant improvement in bandwidth while maintaining the quality of filter roll-off. It is evident that high quality components with wide bandwidth are feasible with low cost fabrication processes using multilayer structures. An analysis of the fabrication error provided essential guidelines to the circuit designers for deciding the degree of alignment accuracy needed for a particular application.