E-Plane Metal-Insert Filters with Pseudo-Elliptic Response

The paper addresses the design of waveguide bandpass filters with pseudo-elliptic response adopting the metalinsert technology. The constraints imposed by the particular technology are taken into account to identify resonant coupling structures capable to act as shunt series resonators, offering at the same time the required coupling coefficient. The proposed solution maintains the inline geometry of a standard metal-insert filter, allowing to place transmission zeros either below or above the passband, as demonstrated by a design example.