Pseudo-elliptic direct-coupled resonator filters based on transmission-zero-generating irises

The paper presents simple realization of pseudo-elliptic bandpass filters where the transmission zeros are generated by coupling irises placed between direct-coupled waveguide cavities. Each iris can be used to generate and control one transmission zero in addition to providing the necessary coupling between the cavities. Example filters are presented to demonstrate the performance of these filters. The same principle is the used to design a bandstop filter with a wide stop-band.