3D printing of EM waveguides in AlSi10Mg using LPBF

Details

Supervisors

Lederer, Dimitri ; Simar, Aude

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électricien, à finalité spécialisée

Abstract

The industrial market for electromagnetic waveguide devices and components is currently aiming at applications such as communication chains for space satellite at frequencies above 100GHz or 6G communication chains. In this context, an interest towards metallic-based Additive Manufacturing (AM) techniques, which are more commonly known as metallic 3D printing techniques, has been growing over the past few years. The AM techniques offer lower fabrication costs and time compared to the Computer Numerical Control (CNC) machining technique which is traditionally used to fabricate waveguide components since the printed structures are directly fabricated in one single piece, thus removing the need for assembly. These AM techniques also offer a significant weight and size reduction of the waveguide components, giving them an advantage over CNC machining for installation on self-sustained low-power space satellites. However, additional losses are observed on the transmitted signals due to the increased surface roughness and reduced conductivity of the printed devices. The objective of this study is thus to investigate the viability in terms of electromagnetic performances of the Laser Powder Bed Fusion (LPBF) AM technique compared to the CNC machining technique for the fabrication of electromagnetic waveguide devices and components. To that end, a LPBF printer available at UCLouvain is first used to fabricate straight rectangular waveguides in AlSi10Mg. The printing parameters of these simple structures are optimized to reach the lowest surface roughness possible with an achieved average surface roughness Ra = 3µm. The S-parameters of these structures are then measured with a VNA and compared to CNC machined waveguides. An additional attenuation ranging from 0.0074 to 0.0182dB/mm as well as a weight reduction of about 60% are obtained. Finally, a demonstrator consisting in a D band bandpass filter with spherical resonators is designed, fabricated and measured to validate the use of LPBF for making waveguide structures with a practical industrial application. The simulation results show good agreement with the literature while the measurements show very poor performances and LPBF is thus identified as a viable alternative to CNC machining under some conditions.