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LEO satellite constellations can provide a viable alternative to expand connectivity to remote, isolated geographical areas and complement existing IoT terrestrial communication infrastructures. This paper aims to improve LEO satellite communications by implementing a new phased antenna array system that can significantly improve the radio communication link's performance. By adjusting the progressive phase shift to each element of the antenna array system, the direction of the main radiation lobe of the phased antenna array system can be controlled with accuracy. As far as we know, it is the first time that a four-element, three-quarter wavelength phased antenna array system has been successfully realized with the intention of being optimized for implementation in LEO IoT satellite reception systems. The proposed system's high level of performance is confirmed by the measurements, which indicate effective control of the main radiation lobe orientation. The numerical analysis shows a maximum gain close to 12 dBi for about 42° elevation, a Half Power Beamwidth (HPBW) of 32° in the vertical plane, and 80° in the azimuth plane. The experimental measurement results at various main lobe orientation angles revealed an HPBW ranging from 76° to 87° in the azimuth plane and a maximum Front-to-Back ratio (F/B) of 14.5 dB.
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http://dx.doi.org/10.3390/s24061915 | DOI Listing |
ACS Nano
September 2025
School of Physics and Key Lab of Quantum Materials and Devices of the Ministry of Education, Southeast University, Nanjing 211189, P. R. China.
While hexagonal boron nitride (hBN) hosts promising room-temperature quantum emitters for hybrid quantum photonic circuits, scalable deterministic integration and insufficient brightness alongside low photon collection and coupling efficiencies remain unresolved challenges. We present a femtosecond laser nanoengineering platform that enables the site-specific generation of hBN single-photon source (SPS) arrays. First-principles density functional theory (DFT) calculations and polarization-resolved spectroscopy confirm the atomic origin of emission as interfacial defects at hBN/SiO heterojunctions.
View Article and Find Full Text PDFInt J Hyperthermia
December 2025
Department of Radiation Oncology Physics, University of Maryland, Baltimore, MD, USA.
Objective: To develop a deep learning method for fast and accurate prediction of Specific Absorption Rate (SAR) distributions in the human head to support real-time hyperthermia treatment planning (HTP) of brain cancer patients.
Approach: We propose an encoder-decoder neural network with cross-attention blocks to predict SAR maps from brain electrical properties, tumor 3D isocenter coordinates and microwave antenna phase settings. A dataset of 201 simulations was generated using finite-element modeling by varying tissue properties, tumor positions, and antenna phases within a human head model equipped with a three-ring phased-array applicator.
Nat Commun
September 2025
State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, China.
Phased arrays are crucial in various technologies, such as radar and wireless communications, due to their ability to precisely control and steer electromagnetic waves. This precise control improves signal processing and enhances imaging performance. However, extending phased arrays to the terahertz (THz) frequency range has proven challenging, especially for high-frequency operation, broadband performance, two-dimensional (2D) phase control with large antenna arrays, and flexible phase modulation.
View Article and Find Full Text PDFSci Rep
August 2025
Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, 00161, Rome, Italy.
This study explores the potential of Bloch surface waves (BSWs) at the interface of a finite one-dimensional photonic crystal (1D-PC) and vacuum, exploiting spectroscopic ellipsometry in a range that encompasses the mid-infrared (4000 cm to 200 cm). BSWs can be excited in both σ and π polarizations, which in the ellipsometric configuration can be detected at the same time, presenting distinct advantages for sensor applications targeting the growth of thin solid films and molecular monolayers, surface-adsorbed gas molecules, and liquid droplets. Compared to other sensing techniques exploiting mid-infrared vibrational absorption lines for chemical-specific sensitivity, like waveguides, nano-antenna arrays, metasurfaces, attenuated total reflectance (ATR) in crystals or in optical fibers, the present approach features high field enhancements, strong field confinement, and large quality factors of the resonances, all while relying on a rather simple and potentially low-cost configuration.
View Article and Find Full Text PDFLight Sci Appl
August 2025
State Key Laboratory of Quantum Optics Technologies and Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.
Exploring the interplay between topology and nonlinearity leads to an emerging field of nonlinear topological physics, which extends the study of fascinating properties of topological states to a regime where interactions between the particles cannot be neglected. For ultracold atomic systems, although many exotic topological states have been recently observed, the nonlinear effect remains elusive. Here, based on the laser-driven couplings of discrete atomic momentum states, we synthesize a topological trimer array, where the atomic interactions give rise to tunable nonlinearities.
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