Terahertz Free-Space Measurement System Using Low-Cost 3D-Printed Hemispherical Lens Antenna

This paper presents a terahertz free-space (THz) measurement technique using a photopolymer-based additive manufactured hemispherical lens antenna directly fed by a WR-3 rectangular waveguide with an operating frequency range of 220 GHz to 320 GHz. The hemispherical lens antenna is fabricated by in-house custom-made low-cost photopolymer 3D printing using a digital light processing (DLP) technique to fabricate layer-by-layer using Monocure 3DR3582C printing material. An asymptotically single-mode all-dielectric Bragg fiber is used to investigate the performance of the developed free-space measurement setup. From the measurement results, the propagation loss in this work has an accuracy compared with an analytical calculation and conventional free-space measurement setup of 83.36% and 88.08%, respectively. Moreover, the use of a 3D-printed hemispherical lens antenna for the THz free-space measurement reduces the complexity of the measurement setup.