Article
Engineering, Electrical & Electronic
Kirill Klionovski, Sergey Bankov
Summary: Recent studies have shown interest in investigating the diffraction of surface waves by junctions of surfaces with different boundary conditions. Many practically applicable surfaces for THz surface waveguides can be described using nontransparent or semitransparent impedance boundary conditions. In this study, rigorous solutions to electromagnetic wave diffraction are found for the junction of a nontransparent impedance wedge and a semitransparent half-plane, as well as the junction of two semitransparent half-planes. These semitransparent surfaces are characterized by generalized semitransparent boundary conditions.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Geochemistry & Geophysics
Ahmet Sefer, Ali Yapar
Summary: This paper presents an algorithm for reconstructing locally rough inaccessible surface profiles using scattered field data and the impedance boundary condition. The algorithm solves the surface integral equation iteratively with the data equation to obtain the image of the surface profile. Numerical examples demonstrate the feasibility and effectiveness of the method.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Tommi E. Rimpilainen, Riku Jantti
Summary: This article presents a method of synthetic beamforming for reconfigurable intelligent surfaces (RIS) using a T-matrix-based multiple scattering model. The method assumes infinite circular cylindrical RIS elements to simplify the 2-D model and assumes that the elements satisfy the impedance boundary condition (IBC) to adjust the phase shift of the scattered field. The beam synthesis is demonstrated analytically and numerically, showing its efficacy in a test case with a linear array of RIS elements.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Computer Science, Information Systems
Varsha Mishra, Filippo Costa, Agostino Monorchio
Summary: A methodology for analyzing the attenuation constant of surface waves in general multilayer structures is proposed, utilizing transmission line theory to define the characteristic equation. The results are validated using completely shielded waveguide structures and applied to analyze surface wave modes in various examples, within a frequency range of 1 to 12 GHz.
Article
Engineering, Electrical & Electronic
Yiqian Mao, Qiwei Zhan, Dezhi Wang, Runren Zhang, Qing Huo Liu
Summary: This paper proposes a method to efficiently simulate thin structures in the finite-element method. By incorporating the surface current boundary condition into the framework of the spectral-element spectral-integral method and treating the thin structures as zero-thickness surfaces, the need for a dense mesh is eliminated. Furthermore, a fast formulation is developed to evaluate the tangential field in the background of doubly periodic structures, improving the accuracy and efficiency of the computations.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Physics, Applied
Jiyeon Lee, Sanghoon Kim, Aobo Li, Dan Sievenpiper
Summary: This paper introduces a shield pattern generated by the point shifting method, which is extended to reduce scattering for apertures and minimize leakage of surface waves. The smooth impedance transition between high and low impedances on the shield patterns enables reduced scattering, which was confirmed through simulations and measurements.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Computer Science, Software Engineering
Yong-Xia Hao, Ting Li
Summary: This paper presents a novel approach to construct quasi-Bezier surfaces from the boundary information based on a general second order functional. The problem is transformed into solving simple linear equations to obtain the internal control points of the resulting quasi-Bezier surface. Representative examples demonstrate the effectiveness of the method.
Article
Engineering, Electrical & Electronic
Do-Hoon Kwon
Summary: This paper presents a method for designing planar modulated reactance surfaces, which are passive and lossless everywhere by optimizing the evanescent part of the aperture fields. When excited by a TM-polarized surface wave, these aperture surfaces can radiate space waves with a prescribed far-zone pattern.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Nanoscience & Nanotechnology
Jooyeon Shin, Jong-Gu Lee, Gunhee Lee, Peter Pikhitsa, Sang Moon Kim, Mansoo Choi, Yong Whan Choi
Summary: This study presents a smart switching surface that can generate and remove wrinkles reversibly to adapt to both wet and dry environments, enabling robots to complete tasks in different conditions. The wrinkles on denser and smaller hexagonal patterns generate six times more friction than non-switching flat surfaces in wet environments, and a similar amount of friction to the flat surfaces in dry environments.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Yunfan Wang, Wenhua Chen, Xingcun Li, Jiaxian Chen, Long Chen, Fei Huang, Shuyang Li, Zhaozhuo Wang
Summary: This article presents a highly efficient terahertz beam-steerable integrated radiator based on tunable boundary conditions. The radiation patterns of the central slot radiator can be altered by tuning the boundary conditions with switched slots. This technique enables a beam-steerable THz antenna with high radiation efficiency. Additionally, the article proposes a 2-D harmonic boosting technique to boost the DC-THz efficiency of the VCO.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2022)
Article
Chemistry, Physical
Danilo Roque Huanca
Summary: The study showed that depositing aluminum on silicon substrates and sintering it leads to the formation of rectangular pits resembling inverted pyramids, with aluminum and oxygen diffusing into the silicon during the process. The concentration of aluminum inside silicon is proportional to sintering time, while oxygen reaches maximum concentration after four hours of sintering.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Binghan Wu, Defeng Yan, Junyi Lin, Jinlong Song
Summary: Superhydrophobic nickel surfaces have superior corrosion protection compared to traditional methods, and the wire electrochemical etching method improves fabrication efficiency. This research contributes to the theory and technology of fabricating superhydrophobic nickel surfaces.
Article
Engineering, Mechanical
Yongdu Ruan, Xu Liang
Summary: The paper proposes a surface impedance matched method for designing reflective elastic metasurfaces and demonstrates their effective control over reflected waves. The results show that the designed metasurface can accurately redirect reflected waves and efficiently suppress scattering waves, potentially enabling functionalities of flexural wave manipulation.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Review
Chemistry, Analytical
Perrine Robin, Sandrine Gerber-Lemaire
Summary: Despite their high sensitivity and miniaturization potential, the reproducibility and specificity of biosensors are still limited for clinical use. This article provides an updated overview of capacitive biosensors in medical applications and summarizes the strategies for fabricating sensing surfaces. It also discusses the characteristics governing the performance of sensing surfaces and recent developments to overcome their current limitations.
Article
Mathematics
Matthias Eller, Illya M. Karabash
Summary: This study focuses on Maxwell equations in Lipschitz domains, describing all dissipative boundary conditions and applying the results to generalized impedance and Leontovich boundary conditions, including cases of singular, degenerate, and randomized impedance coefficients. By constructing Riesz bases and modifying boundary triples, the problem is translated into the operator-theoretic settings of abstract Maxwell operators.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2022)
Article
Engineering, Electrical & Electronic
Mario Vala, Stefania Faria, Pedro Coimbra, Nuno Leonor, Joao M. Felicio, Carlos A. Fernandes, Carlos Eduardo do Rego da Costa Salema, Rafael F. S. Caldeirinha
Summary: This article studies the fading of radiowaves caused by fire plumes resulting from burning piles of pine needles. It presents a detailed characterization of the impact of fire on excess loss in UHF frequencies, particularly in the L-band, under two different ignition sources. The study used a small-scale fire scenario with a metallic grid covered in pine needle fuel above a gas burner to simulate an underbrush situation. The results demonstrate significant changes in the propagation medium due to the influence of the plume, including deep fades and median excess loss. These findings are important for future work in mission-critical communication networks planning.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Engineering, Electrical & Electronic
Stefania Faria, Mario Vala, Pedro Coimbra, Nuno Leonor, Joao M. Felicio, Carlos A. Fernandes, Carlos Salema, Rafael F. S. Caldeirinha
Summary: This letter presents measurement results and initial physical modeling of radio wave propagation phenomena in the presence of fire using Pinus pinaster fuel heaps. Small-scale measurement trials at 700 MHz were carried out on a Pinus pinaster fuel bed on fire, and subsequent simulation results of the propagation phenomena behavior were validated using both the fire dynamics simulator and the cold plasma model. Excessive attenuation of up to 1.52 dB was observed in the measured results, which is considered critical considering the small-scale fire scenario with a 1 x 1 m(2) area and 0.6 kg of pine needles.
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Alvaro F. Vaquero, Jorge Teixeira, Sergio A. Matos, Manuel Arrebola, Jorge R. Costa, Joao M. Felicio, Carlos A. Fernandes, Nelson J. G. Fonseca
Summary: Mechanical beam steering using a single transmitarray can achieve wide-angle scanning for a high-gain antenna, but aberrations caused by the mechanical movement limit the scanning range. This study presents a novel design method for correcting these aberrations and improving scanning performance. A multifocal transmitarray design was manufactured and demonstrated with a scanning range of 50 degrees and a gain of 25 dBi at 30 GHz.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Physics, Multidisciplinary
Tatiana G. Rappoport, Tiago A. Morgado, Sylvain Lannebere, Mario G. Silveirinha
Summary: The study finds that low-symmetry two-dimensional metallic systems can achieve distributed transistor response and characterizes the optical conductivity. By applying strain to bilayer graphene, optical gain can be realized, leading to a distributed transistor response.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Mario G. Silveirinha
Summary: Topological photonics offers a valuable framework to explain complex wave phenomena in electromagnetic systems. The topological index of a physical system is a global property dependent on the operators describing wave propagation. We establish a significant geometric connection between topological physics and the topological theory of mathematical surfaces. Our findings demonstrate that topological band theory extends the surface topological theory, wherein the surface genus can be considered as a Chern number of a suitable surface operator. We also explore the implications of topology in radiation problems and the bulk-edge correspondence in physical systems.
Article
Nanoscience & Nanotechnology
Filipa R. Prudencio, Mario G. Silveirinha
Summary: In this study, it is demonstrated that isorefractive spacetime crystals with a travelling-wave modulation can rigorously mimic the response of moving material systems. Unlike generic spacetime crystals, which exhibit bi-anisotropic coupling in the co-moving frame, isorefractive crystals show an observer-independent response, resulting in isotropic constitutive relations without any bianisotropy. The researchers show how this property can be utilized in calculating the band diagrams of isorefractive spacetime crystals in the laboratory frame and studying synthetic Fresnel drag. Additionally, the impact of considering either a Galilean or a Lorentz transformation in the homogenization of spacetime crystals is discussed, revealing that the effective response is independent of the transformation considered.
Article
Physics, Applied
Filipa R. Prudencio, Mario G. Silveirinha
Summary: We demonstrate that space-time modulations can be used to achieve complex nonreciprocal couplings, particularly the elusive axion response. We develop an analytical formalism for homogenizing anisotropic space-time crystals in the long wavelength limit and find that space-time crystals with appropriate glide-rotation symmetry can exhibit a giant axion-type response, several orders of magnitude larger than in natural materials. The nonreciprocal axion response has interesting potential applications in optics, such as electromagnetic isolation, and can enable exciting forms of light-wave interactions.
PHYSICAL REVIEW APPLIED
(2023)
Article
Engineering, Electrical & Electronic
Matteo Savazzi, Olympia Karadima, David O. Rodriguez Duarte, Jorge Tobon Tobon, Francesca Vipiana, Panagiotis Kosmas, Carlos A. A. Fernandes, Joao M. M. Felicio, Raquel C. C. Conceicao
Summary: This paper assesses the application of microwave tomography (MWT) for the detection of axillary lymph nodes (ALNs) in breast cancer patients. The effects of limited angular view and the possibility of acquiring data in two consecutive steps are numerically studied. The experiments on anthropomorphic phantoms show that the MWT system can detect ALNs in different positions, and it is the first paper to assess ALN MWT in a realistic 3-D experimental scenario.
IEEE JOURNAL OF ELECTROMAGNETICS RF AND MICROWAVES IN MEDICINE AND BIOLOGY
(2023)
Editorial Material
Multidisciplinary Sciences
Mario G. Silveirinha
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Optics
Konstantin Y. Bliokh, Ebrahim Karimi, Miles J. Padgett, Miguel A. Alonso, Mark R. Dennis, Angela Dudley, Andrew Forbes, Sina Zahedpour, Scott W. Hancock, Howard M. Milchberg, Stefan Rotter, Franco Nori, Sahin K. Ozdemir, Nicholas Bender, Hui Cao, Paul B. Corkum, Carlos Hernandez-Garcia, Haoran Ren, Yuri Kivshar, Mario G. Silveirinha, Nader Engheta, Arno Rauschenbeutel, Philipp Schneeweiss, Juergen Volz, Daniel Leykam, Daria A. Smirnova, Kexiu Rong, Bo Wang, Erez Hasman, Michela F. Picardi, Anatoly Zayats, Francisco J. Rodriguez-Fortuno, Chenwen Yang, Jie Ren, Alexander B. Khanikaev, Andrea Alu, Etienne Brasselet, Michael Shats, Jo Verbeeck, Peter Schattschneider, Dusan Sarenac, David G. Cory, Dmitry A. Pushin, Michael Birk, Alexey Gorlach, Ido Kaminer, Filippo Cardano, Lorenzo Marrucci, Mario Krenn, Florian Marquardt
Summary: Structured waves are found in all areas of wave physics, both classical and quantum, where the wavefields are inhomogeneous and cannot be approximated by a single plane wave. These complex wavefields with inhomogeneities are crucial in various fields such as nanooptics, photonics, quantum matter waves, acoustics, water waves, etc. This Roadmap surveys the role of structured waves in wave physics, providing background, current research, and anticipating future developments.
Article
Physics, Applied
Antonio Alex-Amor, Carlos Molero, Mario G. Silveirinha
Summary: This paper presents an analytical framework to study scattering and diffraction phenomena in space-time-modulated metallic gratings. By using a Lorentz transformation, it is shown that a specific class of space-time-modulated gratings acts as moving media. The authors take advantage of this property to derive a closed analytical solution for the wave scattering problem, which allows the avoidance of space-time Floquet-Bloch expansions.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Joao C. Serra, Mario G. Silveirinha
Summary: We introduce a homogenization approach to characterize the dynamical response of a generic dispersive space-time crystal in the long-wavelength limit. The theory is applied to dispersive space-time platforms with a traveling-wave modulation, and it is shown that for long wavelengths the effective response may be described by a frequency-dependent permittivity. The article discusses the peculiar physics exhibited by dispersive space-time crystals, such as anomalous permittivity dispersion, alternate gain and loss regimes, and multiple resonances in the quasistatic regime.
Article
Materials Science, Multidisciplinary
Joao C. Serra, Mario G. Silveirinha
Summary: Topological photonics is a general framework for designing unidirectional edge waveguides and other platforms with extreme nonreciprocal wave phenomena. This study focuses on the topological classification of photonic crystals formed by inclusions subjected to spacetime rotating-wave modulation. The results show that these crystals have a bianisotropic response that breaks time-reversal symmetry and can lead to nontrivial topologies. A proposal for implementing the Haldane model in a spacetime modulated photonic crystal is also presented.
Article
Computer Science, Information Systems
Kesia C. Santos, Carlos A. Fernandes, Jorge R. Costa
Summary: This study systematically evaluates the effectiveness of an air-operated microwave imaging system for detecting thin fractures in superficial bones. It proposes a compact, portable setup with a single Vivaldi antenna for scanning the limb. The antenna operates in monostatic radar mode without contact to ensure hygiene and patient comfort. The study investigates the system resolution, robustness to tissue properties, and patient movement, and confirms the effectiveness and feasibility of the method through experimental validation on an ex-vivo animal leg.
