Near-zero-index (NZI) media, a medium with near zero permittivity and/or permeability, exhibits unique wave phenomena and exciting potential for multiple applications. However, previous proof-of-concept realizations of NZI media based on bulky and expensive platforms are not easily compatible with low-cost and miniaturization demands. Here, we propose the method of substrate-integrated (SI) photonic doping, enabling the implementation of NZI media within a printed circuit board (PCB) integrated design. Additionally, the profile of the NZI device is reduced by half by using symmetries. We validate the concept experimentally by demonstrating NZI supercoupling in straight and curve substrate integrated waveguides, also validating properties of position-independent photonic doping, zero-phase advance and finite group delay. Based on this platform, we propose design of three NZI devices: a high-sensitivity dielectric sensor, an efficient acousto-microwave modulator, and an arbitrarily-curved ‘electric fiber’. Our results represent an important step forward in the development of NZI technologies for microwave/terahertz applications.

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The influence of surface energies on line resolution in screen printing was studied in this paper. Ink wettability on surfaces is decreased by decreasing the surface energies of substrates-the reduction in wettability improves the line resolution. For such high surface-energy substrates as ceramics, the effective means to improve the line resolution is to use high thixotropic inks. On the other hand, for low surface energy polymer substrates, the line resolution can be heightened by increasing the surface energies of inks. If the critical surface tension of a substrate is lower than the surface energy of inks, good line resolution can be achieved even though low viscosity inks were used. The use of low viscosity inks has quite a lot of advantages.

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