3D printed substrate integrated waveguide filters with locally controlled dielectric permittivity

This paper presents, for the first time, the implementation of SIW filters by 3D printing manufacturing technique. The possibility of locally modifying the effective dielectric permittivity by changing the infill factor of the printing process is exploited and demonstrated. This allows adopting a single filament material to obtain different permittivity values in the various portions of a microwave component. Moreover, the variation of the infill factor allows reducing the dielectric loss tangent of the material: this permits increasing the quality factor of cavity filters even by using the same material. These features are illustrated through the design and experimental verification of two SIW filters, with identical frequency response but fabricated with different infill factor of the printing process, via fused deposition modeling (FDM).