Microwave Filter Theory and Design

The first part of this paper gives the theory cf waveguide filters with arbitrary identical links, and their matching to a line. The treatment differs from that previously presented in the literature, in that the electromagnetic state of the impedors and transducers is described by relations between the incident and reflected waves. This simplifies the analysis of all waveguide systems, because each transformation by a line section results only in a phase shift of these waves. Each filter stage is characterized by two angles which can be determined by simple measurements. The formulas which describe the insertion properties of the filters are given in terms of these angles. The second part gives the application of the theory to direct and quarter-wave coupled band-pass iris filters. The design data are given, including correction factors for irises of finite thickness. Measured insertion loss curves of direct couples filters constructed, show good agreement with the theoretical.