An X-band lightweight 3-D printed slotted circular waveguide dual-mode bandpass filter

This paper presents an X-band eighth-order quasi-elliptic circular waveguide dual-mode bandpass filter (BPF) that is manufactured using a fast and low-cost stereolithography-based 3-D printing technique. The 3-D printed filter has advantages of a more convenient integration free of either assembly or post fabrication tuning and furthermore a lightweight of 111 g. A ceramic-filled resin with an enhanced thermal handling capability is used as the filter's building material, which makes the filter capable of operating under much higher temperatures than the one made from ordinary photosensitive resins. Surface metallization of the filter is realized by a layer of electroless plated copper. In the measured passband 8.01–8.44 GHz, the filter exhibits a return loss over 10 dB and a corresponding insertion loss of 0.32–0.68 dB.