Metal Additive Manufactured Freeform Antenna

In this letter, we introduce a metal additive manufactured (AM) freeform antenna using thin, overhanging wires. For most AM processes, overhanging features generally require support structures when building at angles of 45° or greater to the build direction. The need for support structures in an AM antenna fabrication limits the minimum wire diameter possible. The design presented here is a three-dimensional (3-D) spherical helix folded dipole antenna, which has been shown to approach the theoretical limit for the size of antennas called Chu's limit in past research. Electron beam melting enables the creation of this type of antenna geometry in one process using thin, overhanging wires without the need for supports. This demonstrates one of the advantages of AM via complex 3-D space filling geometries. In addition, the impact of the rough AM surface on gain is discussed.