A Very Compact 3D-Printed Doublet Structure Based on a Double Iris and a Pair of Slanting Rods

A novel very compact structure is proposed to realize a doublet for rectangular waveguide filters. The structure consists of a metal septum with a symmetrical double-iris and two slanting rods connected to the septum center on opposite sides. Two poles are produced, along with two transmission zeroes (TZs) one in the lower and the other in the upper stop band. The position of the TZs can be controlled by the iris width. Such a non-conventional geometry with the presence of the slanting rods has been effectively fabricated with a 3D printer. based on Stereolithography (SLA) followed by electroplating [14]. Two doublets have been manufactured and measured demonstrating the feasibility of the proposed structure.