A Versatile 3-D Printable Model for Implementing Multiband Waveguide Filters With Flexible Filtering Characteristics

This paper presents a novel multiband waveguide filter model employing cylindrical resonators arranged horizontally and vertically in Olympic and parallel topologies, respectively. The proposed model has the advantages of reduced footprint and the ability to realise more complex filtering functions. 3 $^{\mathrm{ rd}}$ order dual-band, triple-band, quad-band and 5 $^{\mathrm{ th}}$ order dual-band filters in Ku -band were designed to validate the proposed model. Design flexibility in terms of reconfigurability of centre frequencies and bandwidths is demonstrated with dual-band filter examples. The design strategy is presented and validated with a triple-band filter example. For experimental validation of the proposed model, Selective Laser Melting, a metal Additive Manufacturing technique, was used to fabricate triple-band filter prototypes in copper. Since this model has a complex internal structure, 3-D printing allowed us to avoid complicated assembly and manufacture filters in one piece. The measured results of the four prototypes show a good agreement with the simulations and adequate repeatability.