Characterization of 3D-printed dielectric substrates with different infill for microwave applications

This paper presents the characterization of a 3D printed material based on Ninjaflex filament, through different techniques: the dielectric properties of the material are preliminary retrieved by a waveguide-based method, where a 3D-printed dielectric sample is inserted into a hollow metallic waveguide: this method allows for an accurate and narrow-band characterization. Subsequently, two microstrip lines with different length, realized on a 3D-printed substrate, are used for the broadband characterization in the frequency band from 2 GHz to 20 GHz. The effect of the infill percentage on the dielectric permittivity and loss tangent of the printed material are rigorously investigated and experimentally demonstrated, showing a large tunability when varying the infill from 25% to 100%. These results pave the road to the implementation of novel microwave components, based on the local variation of the dielectric permittivity, and suggest a technique to effectively reduce dielectric losses.