Coupling Matrix Description of WR-3 Waveguide Filter with Multiple Transmission Zeros Created by Source to Load Cross-Coupling

In this paper, a fourth order source to load (SL) cross-coupled WR-3 band (220–325 GHz) waveguide filter is presented. Due to the dispersive characteristic of the SL cross-coupling, two extra transmission zeros (TZs) are obtained, which are not predicted by the common coupling matrix theory. One of these TZs can be positioned freely on the frequency axis while the position of the second one depends on the position of the first one, allowing the realization of asymmetric filter responses. It is shown that the SL coupling proposed in this filter set-up reveals a quadratic frequency dependency. Based on this observation, a coupling matrix description which agrees well with an appropriate discrete equivalent circuit as well as the simulation results can be found. A prototype is manufactured with a high precision CN C milling machine as proof of concept

Effects of Cutting Planes on Filter Performance of FDM 3D-Printed X-Band Waveguide Filters

In this paper, the impact of E-plane and H-plane cuts on filter performance of 3D-printed waveguide filters manufactured with fused deposition modeling (FDM) is examined. The employed manufacturing procedure consists of FDM 3D-printing and the subsequent electroplating process. A number of samples in both configurations are fabricated and surveyed. The measurement results are quantified and a comparison is conducted. Finally, the differing filter behaviors are discussed