Computer-aided synthesis and diagnosis of filters consisting of coupled-resonators and group delay equalizers

Rapid advance of modern satellite and mobile communication systems has imposed extraordinarily stringent specifications on high quality and low manufacturing cost microwave components. Systematic synthesis and diagnosis procedures are necessary for optimum design and post-manufacturing tuning. This dissertation is devoted to the synthesis, diagnosis and tuning of microwave coupled-resonators filters and group delay equalizers.; A systematic synthesis and design procedure, consisting of solving the approximation problem through optimization and synthesis, for microwave coupled resonators group delay equalizers is presented. The effect of the cascading device (circulator or 3dB hybrid coupler) on the flatness of the group delay response is investigated with comparisons made between the externally- and self-equalized structures. A deterministic finite-step tuning algorithm is developed based on the synthesis of the filter network with output short-circuited. The loading effect to the last cavity due to the shift in the reference plane is addressed and effectively removed. A semi-automated tuning procedure, being able to reduce the time required for tuning by at least 50%, is developed through the integration of the algorithm with proper interface development. A new parameter extraction procedure, which eliminates the complexity, inefficiency and non-uniqueness of traditional optimization approach, for symmetric coupled resonators filters is presented. This powerful procedure can also predict the unavoidable spurious couplings between nearby resonators in compact-sized filters. Good agreement with the experimental results demonstrates the feasibility and power of the synthesis and diagnosis procedures.