Waveguide bandstop filter with direct relationships

In traditional waveguide bandstop filters resonators are spread at a distance of 3λ_g/4. Resonators are usually implemented in the form of series stubs (in E-plane). Under relaxed requirements for the steepness of the frequency response, it is possible to build filters on resonant circuits with direct coupling. Resonance probes are placed in reference planes of the E-junction. Experience shows, with such a joint at the expense of the additional coupling, the equivalent Q-factor of the stubs and especially the probes is decreased. For reducing this relationship it is possible to use diaphragms or a stub with a smaller waveguide cross-section