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For the purpose of providing initial designs of waveguide cross-slot couplers, the authors present a simplified analysis of cross-slot coupling through the common broad wall of two rectangular waveguides. Straightforwardly implementable equations are presented which not only include a wide range of cross-slot dimensions but also the location as well as the rotation of the cross-slot in a coupler environment. Moreover, asymmetric coupler structures can be easily incorporated. Analyses of individual structures are verified by HFSS. Two examples of cross-slot waveguide couplers demonstrate the applicability of this technique for the initial design of waveguide cross-slot couplers. [ABSTRACT FROM AUTHOR]

Tolerance analyses of bypass-, cross-and direct-coupled rectangular waveguide filters are presented. It is found that, contrary to common belief, standard direct-coupled waveguide filters are not less sensitive with respect to their passband behaviour than filters with cross or bypass couplings. Moreover, they are considerably larger than bypass-coupled TM110-mode cavity designs, which always present the shortest solution and allow a simple implementation of transmission zeros. The general approach of the tolerance analysis is verified through measurements of a large number of fabricated direct-coupled seven-pole inductive-iris filters. It is concluded that both the path and the radius of the manufacturing end-mill cutter influence the return loss and passband spread of the fabricated filter components. [ABSTRACT FROM AUTHOR]

A new design methodology for a stripline-to-microstrip coupler is presented. Using circular apertures in their common ground plane, it is demonstrated that a design based on profiled circular apertures can be realised within a fraction of a wavelength while maintaining a comparable broadband behaviour. Various key points of the design, such as aperture dimensions and the number of apertures, are discussed. The analysis is based on weak coupling, and includes the mutual interactions of apertures. The theory is validated by measurements of prototypes with a constant, a sine and a cosine profile of apertures. [ABSTRACT FROM AUTHOR]