CAD of rectangular-ridged waveguide bandpass filters.

摘要

This thesis examines the design of rectangular or ridged waveguide bandpass filters using a computer. It studies the analysis of rectangular and ridged waveguide discontinuities using Mode-Matching (MM) and explains how to obtain the Generalized Scattering Matrix (GSM) form the MM analysis. Then, the thesis shows how to combine all the scattering matrices of a microwave circuit to obtain its overall scattering parameters of the circuit. The combination of the MM and GSM method allows the accurate and fast modeling of microwave bandpass filters with rectangular or ridged waveguide cross-sections. A Computer-Aid-Design (CAD) tool is built for the rigorous analysis of an evanescent-mode waveguide filter using the MM-GSM method. A Graphic-User-Interface (GUI) is part of the CAD tool. The user can enter filter parameters and analyze the accurate response of the filter within seconds. The thesis shows a particular design example of an evanescent-mode waveguide filter using the CAD tool. The filter dimensions found using the CAD tool were used to fabricate the filter. The filter was measured and compared with the simulated results. Good agreement between the two results was obtained.