Investigation on 3-D-Printing Technologies for Millimeter- Wave and Terahertz Applications

Three-dimensional-printing technologies have been receiving great attention for a wide variety of applications in recent years for cost effectiveness, eco-friendliness, and process simplicity in complicated structures. This paper describes the challenges and solutions of applying 3-D-printing technologies in fabricating passive millimeter-wave (mmWave) and terahertz (THz) devices. First, we review the state-of-the-art dielectric 3-D-printed passive mmWave and THz devices. Then, we focus on our novel 3-D-printed metallic passive mmWave and THz devices such as horn antennas and waveguides. Next, we analyze the dimensional tolerance and surface roughness of various 3-D-printing technologies in order to provide a guide for choosing an appropriate technology for specific applications. Finally, we summarize the current work and identify the future studies in material powder refinement, surface treatment, optimization of the print process, development of hybrid dielectric and metallic 3-D-printing technology for realizing not only simple mmWave and THz devices but also sophisticated mmWave and THz systems.