A copper pyramidal fractal antenna fabricated with green-laser powder bed fusion

Abstract

Recent advances in additive manufacturing have enabled a new generation of electromagnetic applications to flourish. Complex geometries for dielectrics and conductors can now be simulated and rapidly fabricated from digital data. Powder bed fusion of metals is arguably the most widely adopted additive process by industry and can provide intricately-detailed structures in a wide range of high performance alloys. Copper and copper alloys have remained a challenge in this additive process, as the typical laser wavelength (approximately 1070 nm) used fails to provide sufficient absorption. Moreover, the high thermal conductivity of copper does not allow for the required heat generation for a stable melt pool. However, the recent commercial introduction of the green laser (515 nm wavelength) is enabling the printing of copper, which is particularly interesting for electrical and electromagnetic applications due to the high electrical conductivity and solderability. This paper describes the use of a green laser powder bed fusion system used to fabricate a complex fractal Sierpinski gasket ground structure with an isolated internal pyramid antenna built simultaneously—within and dielectrically isolated from the external ground element: a ship-in-the-bottle design paradigm. The electromagnetic performance, surface finish, dimensional compliance, and conductivity were measured and reported to inform the design of freestanding, geometrically-complex antennas.