Design of 3-D Printed Wideband THz Spatial Power Dividers Based on Two-Stage Phase Optimization Method for Heterodyne Detector Array Applications

This article presents a 3-dimensional (3-D) printed wideband M × M terahertz (THz) spatial power divider (SPD) based on the two-stage phase optimization method. It consists of a feed source and two cascading transmitarrays (TAs), providing independent manipulation of amplitude and phase for M × M focuses. To generate the electric field distribution with equal amplitude and phase for M × M focuses with a small separation, a two-stage phase optimization method is proposed to tune the phases of TAs. The electric field distribution on the target plane with M × M focuses remains constant within a wide bandwidth by using the height-varying dielectric TA element with a linear phase shift. Two 270-GHz 3-D printed 2× 2 and 4× 4 THz SPDs with a focus separation of 2.2 mm are designed and fabricated. For the 2\times 2 and 4\times 4 THz SPDs, the measured amplitude and phase imbalances are in the range of 0.2–0.7 dB and 6°–10° within 230–320 GHz for the former and 1–1.6 dB and 9°–17° within 250–310 GHz for the latter. The proposed wideband M × M THz SPD can be applied for THz heterodyne detector array applications.