Numerical investigation of multiple rectangular aperture irises in rectangular waveguide

It is known that rectangular irises are conventional elements of microwave waveguide circuits. However their application area is limited essentially by their low quality factor. Using multiple aperture irises makes it possible to design circuits with nonconventional features. For example, a design of easily manufactured bandpass filters based on multiple irises with four equal apertures was reported. Frequency response of multiple rectangular irises with different apertures was studied. It appears that such irises have a bandstop feature but this attractive result has been obtained on the basis of an approximate model. So, development of a proper rigorous model is of particular interest. The purpose of this paper is to develop rigorous numerical models of multiple rectangular irises with different apertures and to study their frequency response