Suspended Microstrip Low-Pass Filter Realized Using FDM Type 3D Printing with Conductive Copper-Based Filament

In this paper, the realization of microwave circuits in suspended microstrip structure with a 3D printed conductive enclosure is presented for the first time. An example of a low-pass filter with a cut-off frequency of 2.5 GHz was designed, manufactured and measured. A Fused Deposition Modeling (FDM) type 3D printing and a conductive copper-based filament recently developed by Multi 3D were employed to realize an enclosure serving both mechanical and electrical purposes. The influence of the ground plane conductivity on the total loss within the circuit was studied, and requirements for the conductive material properties were established. Moreover, the impact of the print parameters as well as the connection between microstrip line and SMA connectors was investigated. The obtained measurements proved that the proposed approach is of potential use for circuits and systems operating within low GHz frequency range.