Lightweight 3D printed microwave waveguides and waveguide slot antenna

In this work we demonstrate a lightweight 3D printed waveguide and slot antenna. The waveguide is 78% air by weight with a mass of only 2.2 g/cm which is roughly one ninth that of similar sized solid copper/bronze standard waveguide. Interior scaffolding provides structural strength with insignificant dielectric loss. A 3D Systems 5500 MultiJet printer and an acrylic photo-initiated polymer are used to fabricate the structure. This approach provides an extremely smooth surface with 100 nm root mean square surface roughness. Simulations show that a slotted waveguide antenna can achieve an efficiency of 90% with a copper coating. To demonstrate the concept a waveguide and antenna are fabricated using an easily applied but low conductivity coating. Although the coating is about 20 times less conductive than copper the antenna still achieves a good efficiency of 60%. This approach is a step towards realizing low cost lightweight waveguide microwave circuits and antennas for space born and satellite communications.