Selective Laser Melting aluminum waveguide attenuation at K-band

Additive manufacturing allows for fabrication of highly complex structures that efficiently use a 3D volume of space. Current state of the art metal additive manufacturing methods such as Selective Laser Melting (SLM) allow for intricate parts with high mechanical strength but at the cost of increased surface roughness on internal faces of waveguide structures. This paper investigates the contribution to loss of the increased surface roughness on a set of SLM WR42 waveguides printed with a standard ALSi10Mg aluminum powder, and compares their attenuation performance to purchased single-piece WR42 waveguides and to an industry-standard method for CNC machining waveguide multi-piece assemblies. Single-piece construction of RF parts produces lower attenuation than multi-piece assembly, and lower surface roughness directly leads to lower attenuation, as expected. SLM RF waveguides had better part consistency and comparable or better attenuation performance compared to CNC waveguides, showing that this manu-facturing method has reached the point where it can be used in RF waveguide assemblies.