This work focuses on the impact of the build orientation on additively manufactured waveguide-based hybrid couplers for D-band frequency range and relates it to other sources of uncertainty within the overall manufacturing process and measurement instrumentation for the D-band frequency range. The designed specimens are first printed from UV curable photopolymer resin and subsequently metal coated by an electroless silver plating process, which in turn is improved by making use of the slotted waveguide approach. Although the requirements toward geometrical precision to achieve phase errors below 10° are in an order of 0.1 mm, a desktop grade DLP printer is utilized in this work in order to point out the prospects and limitations of additive manufacturing. Furthermore, waveguide paths with bends are part of the model and their impact on the measured attenuation is estimated explicitly.

Despite this narrow field of tolerances, one specimen could have been realized, which achieves a measured output magnitude imbalance of 0.7 dB over the frequency range from 120 to 155 GHz while at the same time exhibiting a phase deviation of only <10° from the desired 90°. With these demonstrated results, the proposed approach provides suitability for future applications in the D-band frequency range.

Dyeing wastewater has caused serious environmental problems nowadays. In this work, nickel–phosphorus plating–titanium dioxide (Ni-P-TiO2) electroless plating polyimide (PI) fabric was fabricated as an excellent visible light response composite. First, polyaniline (PANI) was in situ polymerized on the surface of the PI fabric. Second, PANI reduced palladium ions to be active seeds for initiating electroless plating of Ni-P-TiO2 layer. Finally, the Ni-P-TiO2/PANI/PI fabric with all-in-one structure was prepared, which can effectively overcome the drawbacks of poor loading fastness and insensitivity to visible light response. It was characterized by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, and ultraviolet–visible diffuse reflectance spectroscopy. The photocatalytic activity was evaluated by degrading reactive blue 19, methylene blue, and reactive red (M-3BE) under visible light irradiation. The results show that the degradation rates of the all three dyes were over 91% with robust cycle stability for repeated 5 cycles of use. The possible photocatalytic degradation mechanism of fabrics was also proposed based on free radical and hole removal experiments.