3-D Printed Customizable Inserts for Waveguide Filter Design at X-Band

This letter presents the design of a customizable 3-D printed insert that can be placed into a standard WR-90 waveguide to realize an inline waveguide filter. These 3-D printed inserts have a significantly lower manufacturing cost and turnaround time compared to the conventional solid copper or bronze waveguide. A two-pole X-Band filter insert has been designed to demonstrate this unique approach. A Stratasys Fortus 400mc 3-D printer is used to print the exchangeable waveguide inserts with support material that is then removed using a basic lye solution. A seed layer of nickel is then spray coated on, and used to electroplate the inserts with copper. Measured results are in good agreement with simulation results for the two-pole bandpass filter with less than 1.05-dB insertion loss over X-Band. The weight of these inserts electroplated with copper is only 6.65 g. The ease and flexibility of this approach provides an excellent option for tuning and customizing filter designs with a fast turnaround using 3-D printing manufacturing technology.