Additive Manufacturing of a Very Compact Doublet Structure with Asymmetric Filtering Function

A novel very compact structure is proposed to realize a doublet capable of both symmetric and asymmetric filtering functions for rectangular waveguide filters. The structure consists of two slanting rods connected to a metal septum with a double-iris. This structure is capable of two pole and two transmission zeroes (TZs) that can be positioned both in the upper stop band or one in the lower and the other in the upper stopband. The positions of the TZs can be easily controlled.The proposed structure has a non-conventional geometry that can be effectively fabricated by additive manufacturing techniques. Several doublet structures have been manufactured by Stereolithography (SLA) and measured demonstrating the feasibility of the proposed geometry.