This work presents the design and optimization of an antenna with defected ground structure (DGS) using characteristic mode analysis (CMA) to enhance bandwidth. This DGS is integrated with a rectangular patch with circular meandered rings (RPCMR) in a wearable format fully using textiles for wireless body area network (WBAN) application. For this integration process, both CMA and the method of moments (MoM) were applied using the same electromagnetic simulation software. This work characterizes and estimates the final shape and dimensions of the DGS using the CMA method, aimed at enhancing antenna bandwidth. The optimization of the dimensions and shape of the DGS is simplified, as the influence of the substrates and excitation is first excluded. This optimizes the required time and resources in the design process, in contrast to the conventional optimization approaches made using full wave "trial and error" simulations on a complete antenna structure. To validate the performance of the antenna on the body, the specific absorption rate is studied. Simulated and measured results indicate that the proposed antenna meets the requirements of wideband on-body operation.
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http://dx.doi.org/10.3390/s21072516 | DOI Listing |
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January 2025
Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing, 100191, P. R. China.
A reasonable construction of hollow structures to obtain high-performance absorbers is widely studied, but it is still a challenge to select suitable materials to improve the low-frequency attenuation performance. Here, the FeO@C@NiO nanoprisms with unique tip shapes, asymmetric multi-path hollow cavity, and core-shell heteroepitaxy structure are designed and synthesized based on anisotropy and intrinsic physical characteristics. Impressively, by changing the load of NiO, the composites achieve strong absorption, broadband, low-frequency absorption: the reflection loss of -55.
View Article and Find Full Text PDFSci Rep
January 2025
Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510631, People's Republic of China.
Prominent platforms based on thin-film lithium niobate (TFLN) are superior integrated-photonics platforms for efficient optical parametric amplification (OPA), however, previously few studies have been systematically reported the gain-boosting performance of TFLN waveguides compared to bulk LN waveguides. Here, we optimize two TFLN waveguides with dispersion engineering for high-efficiency and ultra-broadband gain of OPA, then report comparative results about the efficient ultra-broadband OPA of TFLN waveguides in the case of low loss, optimized waveguide length and pump power. Note that the efficient ultra-broadband OPA of TFLN waveguides is represented by the peak gain (71.
View Article and Find Full Text PDFCarbohydr Polym
March 2025
Biofuels Institute, School of Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China. Electronic address:
Due to the increasing pollution of electromagnetic waves and the vigorous development of intelligent electronic devices, there is great interest in finding high-quality electromagnetic wave absorbing materials for integrated control boxes (ICBs) that integrate various electronic components. Polyaniline (PANI) is a new type of absorbing material with great potential due to its designable structure, simple preparation process, low density and adjustable conductivity. Herein, we prepared BCNF/PANI nanoscale conductive fibers with core-shell structure by in-situ growth of PANI on the surface of bacterial cellulose nanofibers (BCNF) by oxidative polymerization and further prepared cellulose/polyaniline/polyvinyl alcohol (BCNF/PANI/PVA) composite aerogel absorbing material by a freeze-drying process.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093, Zürich, Switzerland.
Quantum magnetometers based on spin defects in solids enable sensitive imaging of various magnetic phenomena, such as ferro- and antiferromagnetism, superconductivity, and current-induced fields. Existing protocols primarily focus on static fields or narrow-band dynamical signals, and are optimized for high sensitivity rather than fast time resolution. Here, we report detection of fast signal transients, providing a perspective for investigating the rich dynamics of magnetic systems.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, Henan, People's Republic of China.
Silicon germanium alloy materials have promising potential applications in the optoelectronic and photovoltaic industries due to their good electronic properties. However, due to the inherent brittleness of semiconductor materials, they are prone to rupturing under harsh working environments, such as high stress or high temperature. Here, we conducted a systematic search for silicon germanium alloy structures using a random sampling strategy, in combination with group theory and graph theory (RG), and 12 stable SiGe structures in 2-8 stacking orders were predicted.
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