Properties of 50–110-GHz Waveguide Components Fabricated by Metal Additive Manufacturing

This paper presents several V-band (50–75 GHz) WR-15 and W-band (75–110 GHz) WR-10 waveguide components fabricated using both direct metal laser sintering in aluminum, nickel-chromium, maraging steel (MS), and copper alloys and stereolithography in copper-coated plastic. Printing resolution is analyzed with respect to feature creation. The RF performance and surface roughness are measured, and the loss due to surface roughness quantified. The measured loss for WR-10 at 92.5-GHz ranges from 5.5 dB/m for the copper-plated plastic waveguides to 36.9 dB/m for the nickel alloy and for WR-15 at 62.5-GHz ranges from 11.0 dB/m for the aluminum alloy to 14.4 dB/m for the MS alloy. From a loss budget study, it is found that standard models do not accurately predict loss due to surface roughness for rough surfaces where the height variation is much larger than skin depth $\delta$ . It is also found that for internally complex printing, the MS alloy versions maintain the closest structure to designed components and expected RF performance. This paper presents the current state-of-the-art in available additive-manufactured waveguide components at V- and W-bands.