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

• Published in: IEEE transactions on microwave theory and techniques Vol. 73; no. 7; pp. 3953 - 3966
• Main Authors: Jun Zhai, Zhen, Lin, Feng, Fai Chan, Ka, Jun Sun, Hou, Wu, Geng-Bo
• Format: Journal Article
• Language: English
• Published: IEEE 01.07.2025
• Subjects: Apertures; Detectors; Electric fields; Feeds; Heterodyne detector array; Optimization methods; Phased arrays; Power dividers; spatial power divider (SPD); terahertz (THz); Terahertz communications; Three-dimensional printing; transmitarray (TA); Wideband
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2024.3507173

This article presents a 3-dimensional (3-D) printed wideband <inline-formula> <tex-math notation="LaTeX">M \times M </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">M \times M </tex-math></inline-formula> focuses. To generate the electric field distribution with equal amplitude and phase for <inline-formula> <tex-math notation="LaTeX">M \times M </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">M \times M </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">4\times 4 </tex-math></inline-formula> THz SPDs with a focus separation of 2.2 mm are designed and fabricated. For the <inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">4\times 4 </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">M \times M </tex-math></inline-formula> THz SPD can be applied for THz heterodyne detector array applications.