WorldWideScience

Sample records for composite electromagnetic wave

  1. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  2. Electromagnetic Waves

    OpenAIRE

    Blok, H.; van den Berg, P.M.

    2011-01-01

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc.

  3. Selective wave-transmitting electromagnetic absorber through composite metasurface

    Science.gov (United States)

    Sun, Zhiwei; Zhao, Junming; Zhu, Bo; Jiang, Tian; Feng, Yijun

    2017-11-01

    Selective wave-transmitting absorbers which have one or more narrow transmission bands inside a wide absorption band are often demanded in wireless communication and radome applications for reducing the coupling between different systems, improving anti-jamming capability, and reducing antennas' radar cross section. Here we propose a feasible method that utilizing composite of two metasurfaces with different polarization dependent characteristics, one works as electromagnetic polarization rotator and the other as a wideband polarization dependent electromagnetic wave absorber. The polarization rotator produces a cross polarization output in the wave-transmitting band, while preserves the polarization of the incidence outside the band. The metasurface absorber works for certain linear polarization with a much wider absorption band covering the wave-transmitting frequency. When combining these two metasurfaces properly, the whole structure behaves as a wideband absorber with a certain frequency transmission window. The proposal may be applied in radome designs to reduce the radar cross section of antenna or improving the electromagnetic compatibility in communication devices.

  4. Surface waves in three-dimensional electromagnetic composites and their effect on homogenization.

    Science.gov (United States)

    Xiong, Xiaoyan Y Z; Jiang, Li Jun; Markel, Vadim A; Tsukerman, Igor

    2013-05-06

    Reflection and transmission of electromagnetic waves at the boundaries of periodic composites (electromagnetic/optical metamaterials) depends in general on both bulk and surface waves. We investigate the interplay of these two contributions using three-dimensional full-wave numerical simulations and a recently developed non-asymptotic homogenization theory.

  5. Electromagnetic ultrasonic guided waves

    CERN Document Server

    Huang, Songling; Li, Weibin; Wang, Qing

    2016-01-01

    This book introduces the fundamental theory of electromagnetic ultrasonic guided waves, together with its applications. It includes the dispersion characteristics and matching theory of guided waves; the mechanism of production and theoretical model of electromagnetic ultrasonic guided waves; the effect mechanism between guided waves and defects; the simulation method for the entire process of electromagnetic ultrasonic guided wave propagation; electromagnetic ultrasonic thickness measurement; pipeline axial guided wave defect detection; and electromagnetic ultrasonic guided wave detection of gas pipeline cracks. This theory and findings on applications draw on the author’s intensive research over the past eight years. The book can be used for nondestructive testing technology and as an engineering reference work. The specific implementation of the electromagnetic ultrasonic guided wave system presented here will also be of value for other nondestructive test developers.

  6. Propagation of shear elastic and electromagnetic waves in one dimensional piezoelectric and piezomagnetic composites.

    Science.gov (United States)

    Shi, P; Chen, C Q; Zou, W N

    2015-01-01

    Coupled shear (SH) elastic and electromagnetic (EM) waves propagating oblique to a one dimensional periodic piezoelectric and piezomagnetic composite are investigated using the transfer matrix method. Closed-form expression of the dispersion relations is derived. We find that the band structures of the periodic composite show simultaneously the features of phononic and photonic crystals. Strong interaction between the elastic and EM waves near the center of the Brillouin zone (i.e., phonon-polariton) is revealed. It is shown the elastic branch of the band structures is more sensitive to the piezoelectric effect while the phonon-polariton is more sensitive to the piezomagnetic effect of the composite. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. One-way absorber for linearly polarized electromagnetic wave utilizing composite metamaterial.

    Science.gov (United States)

    Zhao, Junming; Sun, Liang; Zhu, Bo; Feng, Yijun

    2015-02-23

    This paper presents the proposal and practical design of a one-way absorber for selective linearly polarized electromagnetic (EM) wave. The EM wave polarization rotation property has been combined with polarization selective absorption utilizing a composite metamaterial slab. The energy of certain linearly polarized EM wave can be absorbed along one particular incident direction, but will be fully transmitted through the opposite direction. For the cross polarized wave, the direction dependent propagation properties are totally reversed. A prototype designed with a total slab thickness of only one-sixth of the operating wavelength is verified through both full-wave simulation and experimental measurement in the microwave regime. It achieves absorption efficiency over 83% along one direction, while transmission efficiency over 83% along the opposite direction for one particular linearly polarized wave. The proposed one-way absorber can be applied in EM devices achieving asymmetric transmission for linearly polarized wave or polarization control. The composite metamaterial that combines different functionalities into one design may provide more potential in metamaterial designs for various applications.

  8. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  9. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature.

    Science.gov (United States)

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-19

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4 · 7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  10. "Hearing" Electromagnetic Waves

    Science.gov (United States)

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  11. Application of Local Time Dependent Ion Composition to Observations, Modeling, and Effects of Electromagnetic Ion Cyclotron Waves

    Science.gov (United States)

    Lee, J. H.; Angelopoulos, V.; Chen, L.; Thorne, R. M.

    2014-12-01

    Numerous global magnetospheric studies on electromagnetic ion cyclotron (EMIC) waves have revealed the typical wave properties observed throughout the Earth's magnetosphere. The observed trends in the wave properties at various geocentric distances and local time sectors, although in general agreement, elude satisfactory explanation without further details on the ambient plasma properties, the low-energy (few to ~100 eV) ions in particular. Recent studies also described techniques to deduce the presence and properties of low-energy ions and the application of such a technique to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data has revealed the typical low-energy ion compositional properties throughout the Earth's magnetosphere. Motivated by the recent work on EMIC waves and low-energy ion composition, we analyze typical wave cases observed at each local time sector by the THEMIS satellites and apply the composition techniques or the statistical low-energy ion composition data to constrain the low-energy components in modeling of each wave case in the context of linear hot plasma theory. We find that the observed waves are modeled well with hot plasma theory and both are fully consistent with the composition of the ambient plasma. Our results suggest that combined ion composition and wave measurements are critical for further assessment of the effects of the waves on energetic particles. In the cases we report on here, we find the waves could resonantly interact with electrons at energies in excess of 2 MeV and therefore do not have an effect on the dominant trapped electron population.

  12. REFLECTION OF ELECTROMAGNETIC WAVES FROM SOUND WAVES

    Science.gov (United States)

    The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave is discussed. By analogy with the...with the sound frequency. An experiment is described in which the Bragg reflection of 3 cm electromagnetic waves from a standing sound wave beneath a water surface is observed.

  13. Metamaterial electromagnetic wave absorbers.

    Science.gov (United States)

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electromagnetic fields and waves

    CERN Document Server

    Iskander, Magdy F

    2013-01-01

    The latest edition of Electromagnetic Fields and Waves retains an authoritative, balanced approach, in-depth coverage, extensive analysis, and use of computational techniques to provide a complete understanding of electromagnetic—important to all electrical engineering students. An essential feature of this innovative text is the early introduction of Maxwell's equations, together with the quantifying experimental observations made by the pioneers who discovered electromagnetics. This approach directly links the mathematical relations in Maxwell's equations to real experiments and facilitates a fundamental understanding of wave propagation and use in modern practical applications, especially in today's wireless world. New and expanded topics include the conceptual relationship between Coulomb's law and Gauss's law for calculating electric fields, the relationship between Biot-Savart's and Ampere's laws and their use in calculating magnetic fields from current sources, the development of Faraday's law from e...

  15. Porous CNTs/Co Composite Derived from Zeolitic Imidazolate Framework: A Lightweight, Ultrathin, and Highly Efficient Electromagnetic Wave Absorber.

    Science.gov (United States)

    Yin, Yichao; Liu, Xiaofang; Wei, Xiaojun; Yu, Ronghai; Shui, Jianglan

    2016-12-21

    Porous carbon nanotubes/cobalt nanoparticles (CNTs/Co) composite with dodecahedron morphology was synthesized by in situ pyrolysis of the Co-based zeolitic imidazolate framework in a reducing atmosphere. The morphology and microstructure of the composite can be well tuned by controlling the pyrolysis conditions. At lower pyrolysis temperature, the CNTs/Co composite is composed of well-dispersed Co nanoparticles and short CNT clusters with low graphitic degree. The increase of pyrolysis temperature/time promotes the growth and graphitization of CNTs and leads to the aggregation of Co nanoparticles. The optimized CNTs/Co composite exhibits strong dielectric and magnetic losses as well as a good impedance matching property. Interestingly, the CNTs/Co composite displays extremely strong electromagnetic wave absorption with a maximum reflection loss of -60.4 dB. More importantly, the matching thickness of the absorber is as thin as 1.81 mm, and the filler loading of composite in the matrix is only 20 wt %. The highly efficient absorption is closely related to the well-designed structure and the synergistic effect between CNTs and Co nanoparticles. The excellent absorbing performance together with lightweight and ultrathin thickness endows the CNTs/Co composite with the potential for application in the electromagnetic wave absorbing field.

  16. Electromagnetic waves in stratified media

    CERN Document Server

    Wait, James R; Fock, V A; Wait, J R

    2013-01-01

    International Series of Monographs in Electromagnetic Waves, Volume 3: Electromagnetic Waves in Stratified Media provides information pertinent to the electromagnetic waves in media whose properties differ in one particular direction. This book discusses the important feature of the waves that enables communications at global distances. Organized into 13 chapters, this volume begins with an overview of the general analysis for the electromagnetic response of a plane stratified medium comprising of any number of parallel homogeneous layers. This text then explains the reflection of electromagne

  17. Yolk-Shell Ni@SnO2 Composites with a Designable Interspace To Improve the Electromagnetic Wave Absorption Properties.

    Science.gov (United States)

    Zhao, Biao; Guo, Xiaoqin; Zhao, Wanyu; Deng, Jiushuai; Shao, Gang; Fan, Bingbing; Bai, Zhongyi; Zhang, Rui

    2016-10-26

    In this study, yolk-shell Ni@SnO2 composites with a designable interspace were successfully prepared by the simple acid etching hydrothermal method. The Ni@void@SnO2 composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicate that interspaces exist between the Ni cores and SnO2 shells. Moreover, the void can be adjusted by controlling the hydrothermal reaction time. The unique yolk-shell Ni@void@SnO2 composites show outstanding electromagnetic wave absorption properties. A minimum reflection loss (RLmin) of -50.2 dB was obtained at 17.4 GHz with absorber thickness of 1.5 mm. In addition, considering the absorber thickness, minimal reflection loss, and effective bandwidth, a novel method to judge the effective microwave absorption properties is proposed. On the basis of this method, the best microwave absorption properties were obtained with a 1.7 mm thick absorber layer (RLmin= -29.7 dB, bandwidth of 4.8 GHz). The outstanding electromagnetic wave absorption properties stem from the unique yolk-shell structure. These yolk-shell structures can tune the dielectric properties of the Ni@air@SnO2 composite to achieve good impedance matching. Moreover, the designable interspace can induce interfacial polarization, multiple reflections, and microwave plasma.

  18. Synthesis and Characterization of Composite UPR/Fe3O4 for Its Use as Electromagnetic Wave Absorber

    Science.gov (United States)

    Yusmaniar; Adi, W. A.; Taryana, Y.; Muzaki, R.

    2017-05-01

    Synthesis and characterization of UPR/Fe3O4 composite were performed to evaluate its potency as a electromagnet absorbent. The composite was prepared from the mixture of unsaturated polyester resin and magnetite powder of iron oxide. Fe3O4 was used as filler and unsaturated polyester resins (UPR) was used as a matrix. Fe3O4 magnetite was synthesized from iron objects using electro synthesis method. The raw material was blended in the beaker glass for 120 min and then pressed at temperature of 60 °C for 30 min. The composite is in a semi-crystalline form that consists of amorphous matrix and the various crystalline fillers. The functional group’s analysis of the composite showed that crosslink (bridges) was formed between the chains of individual polymer and between Fe3O4 magnetite filler and UPR matrix. The performance of microwave absorbent measured by VNA method showed the highest RL at the frequency of 10.44 GHz and 11.74 dB. This value was achieved with a composition of 10wt% Fe3O4 and 90wt% UPR. We concluded that the composite of UPR/Fe3O4 has been successfully demonstrated as an electromagnetic wave absorber.

  19. Wave propagation in electromagnetic media

    CERN Document Server

    Davis, Julian L

    1990-01-01

    This is the second work of a set of two volumes on the phenomena of wave propagation in nonreacting and reacting media. The first, entitled Wave Propagation in Solids and Fluids (published by Springer-Verlag in 1988), deals with wave phenomena in nonreacting media (solids and fluids). This book is concerned with wave propagation in reacting media-specifically, in electro­ magnetic materials. Since these volumes were designed to be relatively self­ contained, we have taken the liberty of adapting some of the pertinent material, especially in the theory of hyperbolic partial differential equations (concerned with electromagnetic wave propagation), variational methods, and Hamilton-Jacobi theory, to the phenomena of electromagnetic waves. The purpose of this volume is similar to that of the first, except that here we are dealing with electromagnetic waves. We attempt to present a clear and systematic account of the mathematical methods of wave phenomena in electromagnetic materials that will be readily accessi...

  20. Facile Synthesis of Porous Nickel/Carbon Composite Microspheres with Enhanced Electromagnetic Wave Absorption by Magnetic and Dielectric Losses.

    Science.gov (United States)

    Qiu, Song; Lyu, Hailong; Liu, Jiurong; Liu, Yuzhen; Wu, Nannan; Liu, Wei

    2016-08-10

    Porous nickel/carbon (Ni/C) composite microspheres with diameters of ca. 1.2-1.5 μm were fabricated by a solvothermal method combined with carbon reduction. The pore size of the synthesized Ni/C composite microspheres ranged from several nanometers to 50 nm. The porous Ni/C composite microspheres exhibited a saturation magnetization (MS) of 53.5 emu g(-1) and a coercivity (HC) of 51.4 Oe. When tested as an electromagnetic (EM) wave absorption material, the epoxy resin composites containing 60% and 75% porous Ni/C microspheres provided high-performance EM wave absorption at thicknesses of 3.0-11.0 and 1.6-7.0 mm in the corresponding frequency ranges of 2.0-12 and 2.0-18 GHz, respectively. The superior EM wave absorption performances of porous Ni/C composite microspheres were derived from the synergy effects generated by the magnetic loss of nickel, the dielectric loss of carbon, and the porous structure.

  1. Longitudinal elliptically polarized electromagnetic waves in off-diagonal magnetoelectric split-ring composites.

    Science.gov (United States)

    Chui, S T; Wang, Weihua; Zhou, L; Lin, Z F

    2009-07-22

    We study the propagation of plane electromagnetic waves through different systems consisting of arrays of split rings of different orientations. Many extraordinary EM phenomena were discovered in such systems, contributed by the off-diagonal magnetoelectric susceptibilities. We find a mode such that the electric field becomes elliptically polarized with a component in the longitudinal direction (i.e. parallel to the wavevector). Even though the group velocity [Formula: see text] and the wavevector k are parallel, in the presence of damping, the Poynting vector does not just get 'broadened', but can possess a component perpendicular to the wavevector. The speed of light can be real even when the product ϵμ is negative. Other novel properties are explored.

  2. Focusing of electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Dhayalan, V.

    1996-12-31

    The focusing of electromagnetic waves inside a slab has been examined together with two special cases in which the slab is reduced to a single interface or a single medium. To that end the exact solutions for the fields inside a layered medium have been used, given in terms of the outside current source in order to obtain the solutions for the focused electric field inside a slab. Both exact and asymptotic solutions of the problem have been considered, and the validity of the latter has been discussed. The author has developed a numerical algorithm for evaluation of the diffraction integral with special emphasis on reducing the computing time. The numerical techniques in the paper can be readily applied to evaluate similar diffraction integrals occurring e.g. in microstrip antennas. 46 refs.

  3. A wormhole-like porous carbon/magnetic particles composite as an efficient broadband electromagnetic wave absorber.

    Science.gov (United States)

    Fang, Jiyong; Liu, Tao; Chen, Zheng; Wang, Yan; Wei, Wei; Yue, Xigui; Jiang, Zhenhua

    2016-04-28

    A method combining liquid-liquid phase separation and the pyrolysis process has been developed to fabricate the wormhole-like porous carbon/magnetic nanoparticles composite with a pore size of about 80 nm (WPC/MNPs-80). In this work, the porous structure was designed to enhance interaction between the electromagnetic (EM) wave and the absorber, while the magnetic nanoparticles were used to bring about magnetic loss ability. The structure, morphology, porosity and magnetic properties of WPC/MNPs-80 were investigated in detail. To evaluate its EM wave attenuation performance, the EM parameters of the absorber and wax composite were measured at 2-18 GHz. WPC/MNPs-80 has an excellent EM wave absorbency with a wide absorption band at a relatively low loading and thin absorber thickness. At the absorber thickness of 1.5 and 2.0 mm, minimum RL values of -29.2 and -47.9 dB were achieved with the RL below -10 dB in 12.8-18 and 9.2-13.3 GHz, respectively. The Co and Fe nanoparticles derived from the chemical reduction of Co0.2Fe2.8O4 can enhance the graphitization process of carbon and thus improve dielectric loss ability. Polarizations in the nanocomposite absorber also play an important role in EM wave absorption. Thus, EM waves can be effectively attenuated by dielectric loss and magnetic loss through multiple reflections and absorption in the porous structure. WPC/MNPs-80 could be an excellent absorber for EM wave attenuation; and the design strategy could be extended as a general method to synthesize other high-performance absorbers.

  4. Parametric Instabilities of Electromagnetic Waves in Plasmas,

    Science.gov (United States)

    A simple formalism for the parametric decay of an intense, coherent electromagnetic wave into an electrostatic wave and scattered electromagnetic ... waves in a homogeneous plasma is developed. Various instabilities including Brillouin and Raman backscattering, Compton scattering, filamentation and

  5. Radiation and propagation of electromagnetic waves

    CERN Document Server

    Tyras, George; Declaris, Nicholas

    1969-01-01

    Radiation and Propagation of Electromagnetic Waves serves as a text in electrical engineering or electrophysics. The book discusses the electromagnetic theory; plane electromagnetic waves in homogenous isotropic and anisotropic media; and plane electromagnetic waves in inhomogenous stratified media. The text also describes the spectral representation of elementary electromagnetic sources; the field of a dipole in a stratified medium; and radiation in anisotropic plasma. The properties and the procedures of Green's function method of solution, axial currents, as well as cylindrical boundaries a

  6. Landau levels for electromagnetic wave

    CERN Document Server

    Zyuzin, Vladimir A

    2016-01-01

    In this paper we show that the frequencies of propagating electromagnetic wave (photon) in rotating dielectric media obey Landau quantization. We show that the degeneracy of right and left helicities of photons is broken on the lowest Landau level. In spatially homogeneous system this level is shown to be helical, i.e. left and right helical photons counter-propagate.

  7. Electromagnetic van Kampen waves

    Energy Technology Data Exchange (ETDEWEB)

    Ignatov, A. M., E-mail: aign@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2017-01-15

    The theory of van Kampen waves in plasma with an arbitrary anisotropic distribution function is developed. The obtained solutions are explicitly expressed in terms of the permittivity tensor. There are three types of perturbations, one of which is characterized by the frequency dependence on the wave vector, while for the other two, the dispersion relation is lacking. Solutions to the conjugate equations allowing one to solve the initial value problem are analyzed.

  8. Millimeter waves: acoustic and electromagnetic.

    Science.gov (United States)

    Ziskin, Marvin C

    2013-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. Copyright © 2012 Wiley Periodicals, Inc.

  9. Study of Electromagnetic Wave Absorption Properties of Carbon Nanotubes-Based Composites

    Science.gov (United States)

    2012-11-29

    Publications: [1]. G. L. Zhao, Z. Ye, Z. Li, J. A. Roberts, "New carbon nanotube-epoxy composite for dampening microwave cavity resonance", IEEE Xplore ...Nanotechnology ( IEEE - NANO), 2012 12th IEEE Conference on 20-23 Aug. 2012. [2]. Z. Li, G. L. Zhao, P. Zhang, S. Guo, J. Tang, " Thermoelectric

  10. Science 101: Can Electromagnetic Waves Affect Emotions?

    Science.gov (United States)

    Robertson, Bill

    The answer to this month's question, "Can electromagnetic waves affect emotions," is yes. Wherever there are electromagnetic (EM) waves (basically everywhere!), there is the potential for them directly or indirectly to affect the emotions. But what about the likely motivation behind the originally-posed question? Can EM waves affect your…

  11. Flexible SiC/Si3N4 Composite Nanofibers with in Situ Embedded Graphite for Highly Efficient Electromagnetic Wave Absorption.

    Science.gov (United States)

    Wang, Peng; Cheng, Laifei; Zhang, Yani; Zhang, Litong

    2017-08-30

    SiC/Si3N4 composite nanofibers with in situ embedded graphite, which show highly efficient electromagnetic (EM) wave absorption performance in gigahertz frequency, were prepared by electrospinning with subsequent polymer pyrolysis and annealing. By means of incorporating graphite and Si3N4 into SiC, the EM wave absorption properties of the nanofibers were improved. The relationship among processing, fiber microstructure, and their superior EM wave absorption performance was systematically investigated. The EM wave absorption capability and effective absorption bandwidth (EAB) of nanofibers can be simply controlled by adjusting annealing atmosphere and temperature. The nanofibers after annealing at 1300 °C in Ar present a minimum reflection loss (RL) of -57.8 dB at 14.6 with 5.5 GHz EAB. The nanofibers annealed in N2 at 1300 °C exhibit a minimum RL value of -32.3 dB at a thickness of 2.5 mm, and the EAB reaches 6.4 GHz over the range of 11.3-17.7 GHz. The highly efficient EM wave absorption performance of nanofibers are closely related to dielectric loss, which originated from interfacial polarization and dipole polarization. The excellent absorbing performance together with wider EAB endows the composite nanofibers potential to be used as reinforcements in polymers and ceramics (SiC, Si3N4, SiO2, Al2O3, etc.) to improve their EM wave absorption performance.

  12. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    Science.gov (United States)

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  13. Magnetically Aligned Co-C/MWCNTs Composite Derived from MWCNT-Interconnected Zeolitic Imidazolate Frameworks for a Lightweight and Highly Efficient Electromagnetic Wave Absorber.

    Science.gov (United States)

    Yin, Yichao; Liu, Xiaofang; Wei, Xiaojun; Li, Ya; Nie, Xiaoyu; Yu, Ronghai; Shui, Jianglan

    2017-09-13

    Developing lightweight and highly efficient electromagnetic wave (EMW) absorbing materials is crucial but challenging for anti-electromagnetic irradiation and interference. Herein, we used multiwalled carbon nanotubes (MWCNTs) as templates for growth of Co-based zeolitic imidazolate frameworks (ZIFs) and obtained a Co-C/MWCNTs composite by postpyrolysis. The MWCNTs interconnected the ZIF-derived Co-C porous particles, constructing a conductive network for electron hopping and migration. Moreover, the Co-C/MWCNTs composite was aligned in paraffin matrix under an external magnetic field, which led to a stretch of the MWCNTs along the magnetic field direction. Due to the anisotropic permittivity of MWCNTs, the magnetic alignment considerably increased the dielectric loss of the Co-C/MWCNTs composite. Benefiting from the conductive network, the orientation-enhanced dielectric loss, and the synergistic effect between magnetic and dielectric components, the magnetically aligned Co-C/MWCNTs composite exhibited extremely strong EMW absorption, with a minimum reflection loss (RL) of -48.9 dB at a filler loading as low as 15 wt %. The specific RL value (RL/filler loading) of the composite was superior to that of the previous MOF-derived composite absorbers. It is expected that the proposed strategy can be extended to the fabrication of other lightweight and high-performance EMW-absorbing materials.

  14. Efficient transformer for electromagnetic waves

    Science.gov (United States)

    Miller, R.B.

    A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

  15. Scattering theory of stochastic electromagnetic light waves.

    Science.gov (United States)

    Wang, Tao; Zhao, Daomu

    2010-07-15

    We generalize scattering theory to stochastic electromagnetic light waves. It is shown that when a stochastic electromagnetic light wave is scattered from a medium, the properties of the scattered field can be characterized by a 3 x 3 cross-spectral density matrix. An example of scattering of a spatially coherent electromagnetic light wave from a deterministic medium is discussed. Some interesting phenomena emerge, including the changes of the spectral degree of coherence and of the spectral degree of polarization of the scattered field.

  16. Electromagnetic wave analogue of electronic diode

    OpenAIRE

    Shadrivov, Ilya V.; Powell, David A.; Kivshar, Yuri S.; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2010-01-01

    An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by ...

  17. Coupled seismic and electromagnetic wave propagation

    NARCIS (Netherlands)

    Schakel, M.D.

    2011-01-01

    Coupled seismic and electromagnetic wave propagation is studied theoretically and experimentally. This coupling arises because of the electrochemical double layer, which exists along the solid-grain/fluid-electrolyte boundaries of porous media. Within the double layer, charge is redistributed,

  18. Scattering of electromagnetic waves by obstacles

    CERN Document Server

    Kristensson, Gerhard

    2016-01-01

    The main purpose of Scattering of Electromagnetic Waves by Obstacles is to give a theoretical treatment of the scattering phenomena, and to illustrate numerical computations of some canonical scattering problems for different geometries and materials.

  19. Chemical Ni-C Bonding in Ni-CNT Composite by a Microwave Welding Method and Its Induced High-frequency Radar Frequency Electromagnetic Wave Absorption.

    Science.gov (United States)

    Sha, Linna; Gao, Peng; Wu, Tingting; Chen, Yujin

    2017-11-01

    In this work, a microwave welding method has been used for the construction of chemical Ni-C bonding at the interface between carbon nanotubes (CNTs) and metal Ni in order to provide a different surface electron distribution, which determined the electromagnetic (EM) wave absorption properties based on a surface plasmon resonance (SPR) mechanism. Through a serial of detailed examinations, such as XRD, SEM, TEM, HRTEM, XPS and Raman spectrum etc., the as-expected chemical Ni-C bonding between CNTs and metal Ni has been confirmed. And the BET and surface Zeta potential measurements uncovered the great evolution of structure and electronic density compared with CNTs, metal Ni and Ni-CNT composite without Ni-C bonding. Correspondingly, except the EM absorption due to CNTs and metal Ni in the composite, another wide and strong EM absorption band ranging from 10 GHz to 18 GHz was found, which was induced by the Ni-C bonded interface. The absorption bandwidth with reflection loss less than -10 dB is up to 6.5 GHz (in the frequency range of 10.1-16.6 GHz). With a thinner thickness and more exposed Ni-C interfaces, the Ni-CNT composite displayed a minimum reflection loss, which means that more than 99% EM wave energy attenuated by the absorber.

  20. Special inhomogeneous electromagnetic waves in hyperbolic metamaterials

    Science.gov (United States)

    Kurilkina, S. N.; Petrov, N. S.; Zimin, A. B.; Belyi, V. N.

    2017-12-01

    Herein, it is shown that under conditions of total internal reflection of plane homogeneous electromagnetic waves at the interface of a hyperbolic metamaterial (HMM) and an ordinary isotropic medium, special inhomogeneous electromagnetic waves are excited in certain circumstances near the surface of the metamaterial and their amplitude changes with distance according to the non-exponential law. The existence conditions for such waves are established for the case when the optical axis is located within the interface plane and forms an angle with the plane of incidence. The energy flux and density of energy of special inhomogeneous waves in a HMM are determined.

  1. Propagation of SLF/ELF electromagnetic waves

    CERN Document Server

    Pan, Weiyan

    2014-01-01

    This book deals with the SLF/ELF wave propagation, an important branch of electromagnetic theory. The SLF/ELF wave propagation theory is well applied in earthquake electromagnetic radiation, submarine communication, thunderstorm detection, and geophysical prospecting and diagnostics. The propagation of SLF/ELF electromagnetic waves is introduced in various media like the earth-ionospheric waveguide, ionospheric plasma, sea water, earth, and the boundary between two different media or the stratified media. Applications in the earthquake electromagnetic radiation and the submarine communications are also addressed. This book is intended for scientists and engineers in the fields of radio propagation and EM theory and applications. Prof. Pan is a professor at China Research Institute of Radiowave Propagation in Qingdao (China). Dr. Li is a professor at Zhejiang University in Hangzhou (China).

  2. Electromagnetic waves, gravitational waves and the prophets who predicted them

    OpenAIRE

    Papachristou, Costas J.

    2016-01-01

    Using non-excessively-technical language and written in informal style, this article introduces the reader to the concepts of electromagnetic and gravitational waves and recounts the prediction of existence of these waves by Maxwell and Einstein, respectively. The issue of gravitational radiation is timely in view of the recent announcement of the detection of gravitational waves by the LIGO scientific team.

  3. Relativistic particle motion in nonuniform electromagnetic waves

    Science.gov (United States)

    Schmidt, G.; Wilcox, T.

    1973-01-01

    It is shown that a charged particle moving in a strong nonuniform electromagnetic wave suffers a net acceleration in the direction of the negative intensity gradient of the wave. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities can result.

  4. Terrestrial propagation of long electromagnetic waves

    CERN Document Server

    Galejs, Janis; Fock, V A

    2013-01-01

    Terrestrial Propagation of Long Electromagnetic Waves deals with the propagation of long electromagnetic waves confined principally to the shell between the earth and the ionosphere, known as the terrestrial waveguide. The discussion is limited to steady-state solutions in a waveguide that is uniform in the direction of propagation. Wave propagation is characterized almost exclusively by mode theory. The mathematics are developed only for sources at the ground surface or within the waveguide, including artificial sources as well as lightning discharges. This volume is comprised of nine chapte

  5. Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

    Science.gov (United States)

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-01-01

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7–50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was −25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at −10 dB was up to 5.8 GHz within the frequency range of 2–18 GHz. PMID:25007783

  6. Fundamentals of electromagnetics 2 quasistatics and waves

    CERN Document Server

    Voltmer, David

    2007-01-01

    This book is the second of two volumes which have been created to provide an understanding of the basic principles and applications of electromagnetic fields for electrical engineering students. Fundamentals of Electromagnetics Vol 2: Quasistatics and Waves examines how the low-frequency models of lumped elements are modified to include parasitic elements. For even higher frequencies, wave behavior in space and on transmission lines is explained. Finally, the textbook concludes with details of transmission line properties and applications. Upon completion of this book and its companion Fundame

  7. BIOLOGICAL EFFECTS OF HIGH-FREQUENCY ELECTROMAGNETIC WAVES

    Science.gov (United States)

    In this report the author discusses the influence of high-frequency electromagnetic waves on living matter, especially in the field of microwaves. He...of electromagnetic waves . Symptoms of damage are listed and methods of protection discussed.

  8. Electromagnetic wave propagations in conjugate metamaterials.

    Science.gov (United States)

    Xu, Yadong; Fu, Yangyang; Chen, Huanyang

    2017-03-06

    In this work, by employing field transformation optics, we deduce a special kind of materials called conjugate metamaterials, which can support intriguing electromagnetic wave propagations, such as negative refractions and lasing phenomena. These materials could also serve as substrates for making a subwavelength-resolution lens, and the so-called "perfect lens" is demonstrated to be a limiting case.

  9. Vector plane wave spectrum of an arbitrary polarized electromagnetic wave.

    Science.gov (United States)

    Guo, Hanming; Chen, Jiabi; Zhuang, Songlin

    2006-03-20

    By using the method of modal expansions of the independent transverse fields, a formula of vector plane wave spectrum (VPWS) of an arbitrary polarized electromagnetic wave in a homogenous medium is derived. In this formula VPWS is composed of TM- and TE-mode plane wave spectrum, where the amplitude and unit polarized direction of every plane wave are separable, which has more obviously physical meaning and is more convenient to apply in some cases compared to previous formula of VPWS. As an example, the formula of VPWS is applied to the well-known radially and azimuthally polarized beam. In addition, vector Fourier-Bessel transform pairs of an arbitrary polarized electromagnetic wave with circular symmetry are also derived.

  10. Expanded graphite/Novolac phenolic resin composite as single layer electromagnetic wave absorber for x-band applications

    Science.gov (United States)

    Gogoi, Jyoti P.; Bhattacharyya, Nidhi Saxena

    2013-01-01

    Expanded graphite/novolac phenolic resin (EG/NPR) composites are developed as dielectric absorbers with 4mm thickness and its microwave absorption ability studied in the frequency range 8.4 to 12.4 GHz. A high reflection loss ~ -43 dB is observed at 12.4 GHz for 5 wt. % EG/NPR composites. With the increase in EG concentration in the composite the reflection loss decreases and the absorption peak shifts towards lower frequency. 7 wt. %, 8 wt. % and 10 wt. % composites shows a 10dB absorption bandwidth of order of 1GHz. Light weight EG/NPR composite shows potential to be used as cost-effective broadband microwave absorber over the X-band.

  11. Principles of electromagnetic waves in metasurfaces

    Science.gov (United States)

    Luo, XianGang

    2015-09-01

    Metasurfaces are artificially structured thin films with unusual properties on demand. Different from metamaterials, the metasurfaces change the electromagnetic waves mainly by exploiting the boundary conditions, rather than the constitutive parameters in three dimensional (3D) spaces. Despite the intrinsic similarities in the operational principles of metasurfaces, there is not a universal theory available for the understanding and design of these devices. In this article, we propose the concept of metasurface waves (M-waves) and provide a general theory to describe the principles of such waves. Most importantly, it is shown that the M-waves share some fundamental properties such as extremely short wavelength, abrupt phase change and strong chromatic dispersion, which making them different from traditional bulk waves. We show that these properties can enable many important applications such as subwavelength imaging and lithography, planar optical devices, broadband anti-reflection, absorption and polarization conversion. Our results demonstrated unambiguously that traditional laws of diffraction, refraction, reflection and absorption can be overcome by using the novel properties of M-waves. The theory provided here may pave the way for the design of new electromagnetic devices and further improvement of metasurfaces.

  12. Excitation of surface electromagnetic waves on water.

    Science.gov (United States)

    Singh, A K; Goben, C A; Davarpanah, M; Boone, J L

    1978-11-01

    Excitation of surface electromagnetic waves (SEW) on water was studied using optical coupling techniques at microwave frequencies. Excitation of SEW was also achieved using direct horn antenna coupling. The transmitted SEW power was increased by adding acid and salt to water. The horn antenna gave the maximum excitation efficiency 70%. It was increased to 75% by collimating the electromagnetic beam in the vertical direction. Excitation efficiency for the prism (0 degrees pitch angle) and grating couplers were 15.2% and 10.5% respectively. By changing the prism coupler pitch angle to +36 degrees , its excitation efficiency was increased to 82%.

  13. Effect of electromagnetic waves on human reproduction.

    Science.gov (United States)

    Wdowiak, Artur; Mazurek, Paweł A; Wdowiak, Anita; Bojar, Iwona

    2017-03-31

    Electromagnetic radiation (EMR) emitting from the natural environment, as well as from the use of industrial and everyday appliances, constantly influence the human body. The effect of this type of energy on living tissues may exert various effects on their functioning, although the mechanisms conditioning this phenomenon have not been fully explained. It may be expected that the interactions between electromagnetic radiation and the living organism would depend on the amount and parameters of the transmitted energy and type of tissue exposed. Electromagnetic waves exert an influence on human reproduction by affecting the male and female reproductive systems, the developing embryo, and subsequently, the foetus. Knowledge concerning this problem is still being expanded; however, all the conditionings of human reproduction still remain unknown. The study presents the current state of knowledge concerning the problem, based on the latest scientific reports.

  14. Landau levels for an electromagnetic wave

    Science.gov (United States)

    Zyuzin, Vladimir A.

    2017-10-01

    In this paper we show that the frequencies of propagating electromagnetic waves (photons) in a rotating dielectric medium obey Landau quantization. We show that the degeneracy of right and left helicities of photons is broken on the lowest Landau level. In homogeneous space this level is shown to be helical; i.e., left and right helical photons counterpropagate. This leads to a helical vortical effect for photons, which can be understood as an inverse of the optical torque.

  15. Electromagnetic Wave Interactions with a Metamaterial Cloak

    Science.gov (United States)

    Chen, Hongsheng; Wu, Bae-Ian; Zhang, Baile; Kong, Jin Au

    2007-08-01

    We establish analytically the interactions of electromagnetic wave with a general class of spherical cloaks based on a full wave Mie scattering model. We show that for an ideal cloak the total scattering cross section is absolutely zero, but for a cloak with a specific type of loss, only the backscattering is exactly zero, which indicates the cloak can still be rendered invisible with a monostatic (transmitter and receiver in the same location) detection. Furthermore, we show that for a cloak with imperfect parameters the bistatic (transmitter and receiver in different locations) scattering performance is more sensitive to ηt=μt/γt than nt=μtγt.

  16. Chiral braided and woven composites: design, fabrication, and electromagnetic characterization

    Science.gov (United States)

    Wheeland, Sara; Bayatpur, Farhad; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2011-04-01

    This work presents a new chiral composite composed of copper wires braided with Kevlar and nylon to form conductive coils integrated among structural fiber. To create a fabric, these braids were woven with plain Kevlar fiber. This yielded a composite with all coils possessing the same handedness, producing a chiral material. The electromagnetic response of this fabric was first simulated using a finite element full-wave simulation. For the electromagnetic measurement, the sample was placed between two lens-horn antennas connected to a Vector Network Analyzer. The frequency response of the sample was scanned between 5.5 and 8GHz. The measured scattering parameters were then compared to those of the simulated model. The measured parameters agreed well with the simulation results, showing a considerable chirality within the measured frequency band. The new composite combines the strength and durability of traditional composites with an electromagnetic design to create a multifunctional material.

  17. Electromagnetic Fields and Waves in Fractional Dimensional Space

    CERN Document Server

    Zubair, Muhammad; Naqvi, Qaisar Abbas

    2012-01-01

    This book presents the concept of fractional dimensional space applied to the use of electromagnetic fields and waves. It provides demonstrates the advantages in studying the behavior of electromagnetic fields and waves in fractal media. The book presents novel fractional space generalization of the differential electromagnetic equations is provided as well as a new form of vector differential operators is formulated in fractional space. Using these modified vector differential operators, the classical Maxwell's electromagnetic equations are worked out. The Laplace's, Poisson's and Helmholtz's

  18. Electromagnetic Energy Localization and Characterization of Composites

    Science.gov (United States)

    2013-01-01

    Drewniak, and B. Archam- beault, “Numerical modeling of periodic composite media for electromagnetic shield - ing application,” 2007 IEEE Int. Symp. on...Electromagnetic Compatibility ( EMC 2007), July 9–13, 2007, pp. 1–5. [40] M. Luo, C. Liu, and H. P. Pan, “Numerical simulation on dielectric enhancement of

  19. Surface-plasmon-assisted electromagnetic wave propagation.

    Science.gov (United States)

    Yang, Wenbo; Reed, Jennifer M; Wang, Haining; Zou, Shengli

    2010-10-21

    Using electrodynamics tools, we investigated the effect of surface plasmons on the propagation direction of electromagnetic waves around a spherical silver nanoparticle and nano-structured silver film. The studies showed that the calculated effective index of refraction of a spherical silver nanoparticle from the Kramers-Kronig transformation method may not represent the index of refraction of the system but is consistent with the Poynting vector (the energy flow) direction at the microscopic scale. Using a silver film composed of periodic triangular prisms, we numerically demonstrated that electromagnetic waves may propagate along different directions depending on the incident polarization direction. When the incident polarization is in the plane of incidence and the surface plasmons are excited, the refracted light ray propagates along the same side of the surface normal as the incident wave. When the incident polarization is perpendicular to the plane of incidence, the refracted light ray always propagates on the opposite side of the surface normal. The results show that a silver film composed of periodic nano-sized triangular prisms may be used as a filter to simultaneously generate two polarized light rays of orthogonal polarizations from one light source.

  20. Do electromagnetic waves always propagate along null geodesics?

    CERN Document Server

    Asenjo, Felipe A

    2016-01-01

    We find exact solutions to Maxwell equations written in terms of four-vector potentials in non--rotating, as well as in G\\"odel and Kerr spacetimes. Exact electromagnetic waves solutions are written on given gravitational field backgrounds where they evolve. We find that in non--rotating spherical symmetric spacetimes, electromagnetic plane waves travel along null geodesics. However, electromagnetic plane waves on G\\"odel and Kerr spacetimes do not exhibit that behavior.

  1. Carbon nanostructure composite for electromagnetic interference ...

    Indian Academy of Sciences (India)

    2015-05-30

    based composite materials for electromagnetic interference (EMI) shielding. With more and more electronic gadgets being used at different frequencies, there is a need for shielding them from one another to avoid interference.

  2. Electromagnetic Wave Propagation in Random Media

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1984-01-01

    The propagation of a narrow frequency band beam of electromagnetic waves in a medium with randomly varying index of refraction is considered. A novel formulation of the governing equation is proposed. An equation for the average Green function (or transition probability) can then be derived....... A Fokker-Planck type equation is contained as a limiting case. The results are readily generalized to include the features of the random coupling model and it is argued that the present problem is particularly suited for an analysis of this type....

  3. Self‐propagating Combustion Triggered Synthesis of  3D Lamellar Graphene/BaFe12O19 Composite and Its  Electromagnetic Wave Absorption Properties

    Directory of Open Access Journals (Sweden)

    Tingkai Zhao

    2017-03-01

    Full Text Available The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self‐propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB. The 3D lamellar graphene structures could consume the incident waves through multiple Reflection and scattering within the layered structures, Prolonging the propagation path of electromagnetic waves in the absorbers.

  4. Complex space source theory of spatially localized electromagnetic waves

    CERN Document Server

    Seshadri, SR

    2013-01-01

    The author highlights that there is a need obtain exact full-wave solutions that reduce to the paraxial beams in the appropriate limit. Complex Space Source Theory of Spatially Localized Electromagnetic Waves treats the exact full-wave generalizations of all the basic types of paraxial beam solutions. These are developed by the use of Fourier and Bessel transform techniques and the complex space source theory of spatially localized electromagnetic waves is integrated as a branch of Fourier optics.

  5. influence of electromagnetic waves produced by an amplitude ...

    African Journals Online (AJOL)

    PROF EKWUEME

    2. Theory. 2.1. Excess minority carriers' density. Polycrystalline back surface field silicon solar cell with n+-p-p+ structure is studied under monochromatic illumination and under electromagnetic waves (figure 1). Figure 1: Silicon solar cell illuminated by monochromatic light and under electromagnetic waves influence.

  6. Influence of electromagnetic waves produced by an amplitude ...

    African Journals Online (AJOL)

    This article presents a one dimensional modeling of the influence of electromagnetic waves on the electric power delivered by a silicon solar cell under monochromatic illumination in steady state. The electromagnetic waves are produced by an amplitude modulation radio antenna of 2MW power of radiation and located at a ...

  7. The plane wave spectrum representation of electromagnetic fields

    CERN Document Server

    Clemmow, P C

    1966-01-01

    The Plane Wave Spectrum Representation of Electromagnetic Fields presents the theory of the electromagnetic field with emphasis to the plane wave. This book explains how fundamental electromagnetic fields can be represented by the superstition of plane waves traveling in different directions. Organized into two parts encompassing eight chapters, this book starts with an overview of the methods whereby plane wave spectrum representation can be used in attacking different characteristic problems belonging to the theories of radiation, diffraction, and propagation. This book then discusses the co

  8. High latitude electromagnetic plasma wave emissions

    Science.gov (United States)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  9. Interface Polarization Strategy to Solve Electromagnetic Wave Interference Issue.

    Science.gov (United States)

    Lv, Hualiang; Guo, Yuhang; Wu, Guanglei; Ji, Guangbin; Zhao, Yue; Xu, Zhichuan J

    2017-02-15

    Design of an interface to arouse interface polarization is an efficient route to attenuate high-frequency electromagnetic waves. The attenuation intensity is highly related to the contact area. To achieve stronger interface polarization, growing metal oxide granular film on graphene with a larger surface area seems to be an efficient strategy due to the high charge carrier concentration of graphene. This study is devoted to fabricating the filmlike composite by a facile thermal decomposition method and investigating the relationship among contact area, polarization intensity, and the type of metal oxide. Because of the high-frequency polarization effect, the composites presented excellent electromagnetic wave attenuation ability. It is shown that the optimal effective frequency bandwidth of graphene/metal oxide was close to 7.0 GHz at a thin coating layer of 2.0 mm. The corresponding reflection loss value was nearly -22.1 dB. Considering the attenuation mechanism, interface polarization may play a key role in the microwave-absorbing ability.

  10. Switchable metamaterial reflector/absorber for different polarized electromagnetic waves

    OpenAIRE

    Zhu, Bo; Feng, Yijun; Zhao, Juming; Huang, Ci; Jiang, Tian

    2010-01-01

    We demonstrate a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes. Through biasing at different voltages to turn ON and OFF the diodes, we are able to switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave. By arranging orthogonally orientated resonant cells, the metamaterial can react to different polarized waves by s...

  11. Search For Gravitational Waves Through the Electromagnetic Faraday Rotation

    OpenAIRE

    Halilsoy, Mustafa; Gürtuğ, Özay

    2006-01-01

    A method is given which renders indirect detection of strong gravitational waves possible. This is based on the reflection (collision) of a linearly polarized electromagnetic shock wave from (with) a cross polarized impulsive and shock gravitational waves in accordance with the general theory of relativity. This highly non-linear process induces a detectable Faraday rotation in the polarization vector of the electromagnetic field. The file in this item is the publisher version (published v...

  12. Electromagnetic wave probing of Earth's environment

    Science.gov (United States)

    Kong, Jin AU

    1988-01-01

    Polarimetric radar backscattering from anisotropic Earth terrain such as snow-covered ice fields and vegetation fields with row structures provides a challenging modeling problem from the electromagnetic wave point of view. Earth terrain covers are modeled as random media characterized by different dielectric constants and correlation functions. A three-layer model will be used to simulate a vegetation field or a snow-covered ice field with the top layer being snow or leaves, the middle layer being ice of trunks, and the bottom layer being sea water or ground. The volume scattering effects of snow-covered sea ice are studied with a three-layer random medium model for microwave remote sensing. The strong fluctuation theory and the bilocal approximation are applied to calculate the effective permittivities for snow and sea ice. The wave scattering theory in conjunction with the distorted Born approximation is then used to compute bistatic coefficients and backscattering cross sections. Theoretical results are illustrated by matching experimental data for dry snow-covered thick first-year sea ice at Point Barrow. The results derived can also be applied to the passive remote sensing by calculating the emissivity from the bistatic scattering coefficients.

  13. Metamaterial Composites with Tunable Electromagnetic Properties

    Science.gov (United States)

    Wheeland, Sara Ruth

    A broadening application range has increased demand for advanced RF control. Recent research has identified several metamaterials to provide this control. This work seeks to expand this idea through several novel metamaterials with enhanced electromagnetic properties. First copper wires braided with Kevlar and nylon to form conductive coils are woven among structural fiber to create a fabric. This yielded a composite with all coils possessing the same handedness, producing a chiral material. The measured scattering parameters showed considerable chirality within the 5.5-8GHz frequency band, agreeing with simulation results. Electronic chirality tuning is investigated by integrating varactor diodes into an array of helical elements on a printed circuit board. Applying a varied reverse bias voltage across the sample effectively tunes the chiral behavior of the material. The measurements demonstrate the feasibility of creating a rigid helix composite with tuned chirality in the 5.5-12.4GHz frequency band. Chirality can be further tuned mechanically through the deformation of an array of conductive coils. Parallel, metallic helices embedded in a polyurethane matrix are subjected to mechanical stretching for pitch adjustment. This change in pitch directly affects the overall chirality of the composite. Repeatable elastic deformation is achieved up to 50% axial strain. Over the 5.5-12.5GHz frequency range, an increase of 30% axial strain yields an ˜18% change in axial chirality. Hyperbolic microwave focusing is explored through an indefinite medium with anisotropic permittivity. An array of 12-gauge brass wires is embedded in Styrofoam and scanned over the 7-9GHz frequency band to establish focusing patterns. A soft-focusing spot is observed at 7.6GHz with a relative gain of ˜7dB over averaged background. Applying an axial refractive gradient to a coil composite creates a lens capable of fine adjustment in the microwave range. The gradient required to achieve sharp

  14. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium.

    Science.gov (United States)

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-06-15

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium.

  15. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    Science.gov (United States)

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  16. Do electromagnetic waves always propagate along null geodesics?

    Science.gov (United States)

    Asenjo, Felipe A.; Hojman, Sergio A.

    2017-10-01

    We find exact solutions to Maxwell equations written in terms of four-vector potentials in non-rotating, as well as in Gödel and Kerr spacetimes. We show that Maxwell equations can be reduced to two uncoupled second-order differential equations for combinations of the components of the four-vector potential. Exact electromagnetic waves solutions are written on given gravitational field backgrounds where they evolve. We find that in non-rotating spherical symmetric spacetimes, electromagnetic waves travel along null geodesics. However, electromagnetic waves on Gödel and Kerr spacetimes do not exhibit that behavior.

  17. Electromagnetic shock wave in nonlinear vacuum: exact solution.

    Science.gov (United States)

    Kovachev, Lubomir M; Georgieva, Daniela A; Kovachev, Kamen L

    2012-10-01

    An analytical approach to the theory of electromagnetic waves in nonlinear vacuum is developed. The evolution of the pulse is governed by a system of nonlinear wave vector equations. An exact solution with its own angular momentum in the form of a shock wave is obtained.

  18. Electromagnetic Wave Absorption Coating Material with Self-Healing Properties.

    Science.gov (United States)

    Wang, Ya-Min; Pan, Min; Liang, Xiang-Yong; Li, Bang-Jing; Zhang, Sheng

    2017-11-02

    Electromagnetic wave absorption coatings can effectively minimize electromagnetic radiation and are widely used in the military and civil field. However, even small scratches on the coating can lead to a large decline of absorption ability and bring serious consequences. To enhance the lifetime of electromagnetic wave absorbing coating, a kind of self-healing electromagnetic wave absorbing coating is developed by introducing host-guest interactions between the absorbing fillers and polymer matrix. After being damaged, the cracks on this coating can be healed completely with the aid of small amounts of water. Simultaneously, the electromagnetic absorbing ability of the coating is restored along with the self-healing process. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Electromagnetic radiation accompanying gravitational waves from black hole binaries

    Science.gov (United States)

    Dolgov, A.; Postnov, K.

    2017-09-01

    The transition of powerful gravitational waves, created by the coalescence of massive black hole binaries, into electromagnetic radiation in external magnetic fields is considered. In contrast to the previous calculations of the similar effect we study the realistic case of the gravitational radiation frequency below the plasma frequency of the surrounding medium. The gravitational waves propagating in the plasma constantly create electromagnetic radiation dragging it with them, despite the low frequency. The plasma heating by the unattenuated electromagnetic wave may be significant in hot rarefied plasma with strong magnetic field and can lead to a noticeable burst of electromagnetic radiation with higher frequency. The graviton-to-photon conversion effect in plasma is discussed in the context of possible electromagnetic counterparts of GW150914 and GW170104.

  20. fdtd modelling of electromagnetic waves in stratified medium

    African Journals Online (AJOL)

    BRIAN

    (perfect electromagnetic conductors) based on. FDTD technique. The first is an analytic approach, based on the propagators and wave- splitting technique and the second is the numerical FDTD method. Hybrid finite element finite-difference time-domain. (FE/FDTD) technique for solving complex electromagnetic problems ...

  1. Electromagnetic Lead Screw for Potential Wave Energy Application

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Wu, Weimin

    2014-01-01

    This paper presents a new type electromagnetic lead screw (EMLS) intended for wave energy application. Similar to the mechanical lead screw, this electromagnetic version can transfer slow linear motion to high-rotational motion, offering gearing effects. Compared with the existing pure magnetic...

  2. Electromagnetic aquametry electromagnetic wave interaction with water and moist substances

    CERN Document Server

    Kupfer, Klaus

    2006-01-01

    This book covers all aspects of Electromagnetic Aquametry. It summarizes the wide area of metrology and its applications in electromagnetic sensing of moist materials. The physical properties of water in various degrees of binding interacting with electromagnetic fields is presented by model systems. The book describes measurement methods and sensors in the frequency domain, TDR-techniques for environmental problems, methods and sensors for quality assessment of biological substances, and nuclear magnetic resonance techniques. Environmental sciences, as well as civil and geoengineering, fossil fuels, food and pharmaceutical science are the main fields of application. A very wide frequency sprectrum is used for dielectric measurement methods, but the microwave range is clearly dominant. Multiparameter methods as well as methods of principal components and artificial neural networks for density independent measurements are described.

  3. Electromagnetic wave propagation in alternating material-metamaterial layered structures

    CERN Document Server

    Carrera-Escobedo, V H

    2016-01-01

    Using the transfer matrix method, we examine the parametric behavior of the transmittance of an electromagnetic plane wave propagating in the lossless regime through a periodic multilayered system as a function of the frequency and angle of incidence of the electromagnetic wave for the case in which the periodic structure comprises alternating material-metamaterial layers. A specific example of high transmittance at any angle of incidence in the visible region of the spectrum is identified

  4. Efficient and Lightweight Electromagnetic Wave Absorber Derived from Metal Organic Framework-Encapsulated Cobalt Nanoparticles.

    Science.gov (United States)

    Wang, Haicheng; Xiang, Long; Wei, Wei; An, Jing; He, Jun; Gong, Chunhong; Hou, Yanglong

    2017-12-06

    Porous-carbon-based nanocomposites are gaining tremendous interest because of good compatibility, lightweight, and strong electromagnetic wave absorption. However, it is still a great challenge to design and synthesize porous-carbon-based composites with strong absorption capability and broad frequency bandwidth. Herein, a facile and effective method was developed to synthesize Co magnetic nanoparticles/metal organic framework (MOF) (Co NPs/ZIF-67) nanocomposites. Co NPs/porous C composites were subsequently obtained by annealing Co NPs/ZIF-67 nanocomposites at different temperatures under an inert atmosphere. The carbonized nanocomposites showed highly efficient electromagnetic wave absorption capability. Specifically, the optimal composite (i.e., Co/C-700) possessed a maximum reflection loss (RL) value of -30.31 dB at 11.03 GHz with an effective absorption bandwidth (RL ≤ -10 dB) of 4.93 GHz. The electromagnetic parameters and the absorption performance of the composites are readily tunable by adjusting the carbonization temperature and the concentration of Co NPs in the composites. Because of the combination of good impedance matching, dual-loss mechanism, and the synergistic effect between Co NPs and porous carbon composites, these Co NPs/MOF-derived composites are attractive candidates for electromagnetic wave absorbers.

  5. Nonlinear multi-frequency electromagnetic wave propagation phenomena

    Science.gov (United States)

    Valovik, Dmitry V.

    2017-11-01

    A generalisation of the concept of monochromatic electromagnetic waves guided by layered waveguide structures filled with non-linear medium is introduced. This generalisation leads to guided waves of a novel type: a non-linear multi-frequency guided wave. The existence of such waves, in particular guide structures, is proven using the perturbation method. Numerical experiments are presented for non-linear 1- and 2-frequency guided waves in plane and cylindrical (with a circular cross-section) waveguides. Numerically, a novel non-linear effect is found for particular cases of non-linear multi-frequency guided waves. The suggested generalisation gives not only a unified approach to treat various electromagnetic wave propagation problems but also paves the way to study non-linear interactions of guided waves.

  6. Nanometer-scale surface modification of epoxy with carbon black and electromagnetic waves.

    Science.gov (United States)

    Kim, Bu Gi; Lee, Dai Gil

    2010-05-07

    The surface morphology of polymers and polymer composites strongly influences both the adhesive bonding strength of composite structures and the electrical conduction through carbon fiber composites. Conventional surface modification techniques (such as mechanical abrading, chemical treatment, plasma treatment and flame treatment) not only damage the surfaces of polymers and polymer composites but also increase production cost. In this study, the surface of epoxy was modified by heating carbon black with electromagnetic waves in order to generate nanometer-sized grooves. A thermal transfer model was developed to investigate the generation mechanism of the grooves and the process variables. In the surface modification technique, electromagnetic waves and carbon black were used to improve both the bonding strength and the electrical conductivity of the composite in a fast and efficient way.

  7. On new electromagnetic waves in a multicomponent insulator

    NARCIS (Netherlands)

    Dubovik, V. M.

    The dispersion equation for additional transverse electromagnetic waves in a multicomponent amorphous insulator is analyzed in the vicinity of a narrow absorption line. Such waves can be excited due to spatial dispersion associated with fluctuation of the polarizability of insulator molecules. The

  8. An Apparatus for Constructing an Electromagnetic Plane Wave Model

    Science.gov (United States)

    Kneubil, Fabiana Botelho; Loures, Marcus Vinicius Russo; Amado, William

    2015-01-01

    In this paper we report on an activity aimed at building an electromagnetic wave. This was part of a class on the concept of mass offered to a group of 20 pre-service Brazilian physics teachers. The activity consisted of building a plane wave using an apparatus in which it is possible to fit some rods representing electric and magnetic fields into…

  9. Statistical Characterization of Electromagnetic Wave Propagation in Mine Environments

    KAUST Repository

    Yucel, Abdulkadir C.

    2013-01-01

    A computational framework for statistically characterizing electromagnetic (EM) wave propagation through mine tunnels and galleries is presented. The framework combines a multi-element probabilistic collocation method with a full-wave fast Fourier transform and fast multipole method accelerated surface integral equation-based EM simulator to statistically characterize fields from wireless transmitters in complex mine environments. 1536-1225 © 2013 IEEE.

  10. Joint evaluation of fracture azimuth by electromagnetic wave and elastic wave

    Science.gov (United States)

    Feng, Xuan; Liu, Cai; Wang, Qiao; Wang, Kai; Lu, Qi; Xue, Jian; Liang, Wenjing; Yu, Yue; Ren, Qianci

    2013-12-01

    With the multi-wave, multi-component seismic wave exploration, one can apply the anisotropy of fracture media to analyze the attributes of the fracture media, including the fracture azimuth. In the meantime, the techniques of full-polarimetric electromagnetic wave, including full-polarimetric borehole radar, can also be used to analyze the attributes of the fracture. However, the analysis precision of both the multi-component elastic wave exploration and full-polarimetric electromagnetic wave exploration is prone to the influence of noise and other factors. So far, some researchers have conducted studies on the joint inversion of electromagnetic waves and seismic waves. This paper develops evaluation techniques of fracture azimuth by electromagnetic wave, elastic wave, and joint analysis of coincident elastic reflection and electromagnetic data. Firstly, based on the shear wave splitting of elastic waves, this paper develops a statistical analysis technique which applies Pearson correlation coefficient to count and analyze the azimuth angle of fracture. Secondly, based on the information of electromagnetic polarization rotated by fracture, this paper develops a statistical analysis method of full-polarimetric electromagnetic waves which applies the maximum amplitude ratio between the co-polarization and cross-polarization to analyze the azimuth angle of fracture. Furthermore, based on the analysis result of the elastic wave and full-polarimetric electromagnetic wave, this paper develops a joint analysis technique which adopts the standard deviation. At last, authors in this study conduct joint detection experiments on the coincident fracture medium by using the ultrasonic and full-polarimetric ground penetrating radar. The experimental result indicates that both single geophysical methods are capable of analyzing the fracture azimuth angle, but the joint analysis is more accurate.

  11. Transition operators in electromagnetic-wave diffraction theory - General theory

    Science.gov (United States)

    Hahne, G. E.

    1992-01-01

    A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.

  12. Metamaterial-based wideband electromagnetic wave absorber.

    Science.gov (United States)

    La Spada, Luigi; Vegni, Lucio

    2016-03-21

    In this paper, an analytical and numerical study of a new type of electromagnetic absorber, operating in the infrared and optical regime, is proposed. Absorption is obtained by exploiting Epsilon-Near-Zero materials. The structure electromagnetic properties are analytically described by using a new closed-form formula. In this way, it is possible to correlate the electromagnetic absorption properties of the structure with its geometrical characteristics. Good agreement between analytical and numerical results was achieved. Moreover, an absorption in a wide angle range (0°-80°), for different resonant frequencies (multi-band) with a large frequency bandwidth (wideband) for small structure thicknesses (d = λp/4) is obtained.

  13. Relativistic electromagnetic waves in an electron-ion plasma

    Science.gov (United States)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  14. Absorption of electromagnetic and gravitational waves by Kerr black holes

    Science.gov (United States)

    Leite, Luiz C. S.; Dolan, Sam R.; Crispino, Luís C. B.

    2017-11-01

    We calculate the absorption cross section for planar waves incident upon Kerr black holes, and present a unified picture for scalar, electromagnetic and gravitational waves. We highlight the spin-helicity effect that arises from a coupling between the rotation of the black hole and the helicity of a circularly-polarized wave. For the case of on-axis incidence, we introduce an extended 'sinc approximation' to quantify the spin-helicity effect in the strong-field regime.

  15. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    Science.gov (United States)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-01-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet–height and diameter– and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials. PMID:26354891

  16. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets.

    Science.gov (United States)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-09-10

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  17. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    Science.gov (United States)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2015-09-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  18. Electromagnetic wave chaos in gradient refractive index optical cavities.

    Science.gov (United States)

    Wilkinson, P B; Fromhold, T M; Taylor, R P; Micolich, A P

    2001-06-11

    Electromagnetic wave chaos is investigated using two-dimensional optical cavities formed in a cylindrical gradient refractive index lens with reflective surfaces. When the planar ends of the lens are cut at an angle to its axis, the geometrical ray paths are chaotic. In this regime, the electromagnetic mode spectrum of the cavity is modulated by both real and ghost periodic ray paths, which also "scar" the electric field intensity distributions of many modes. When the cavity is coupled to waveguides, the eigenmodes generate complex series of resonant peaks in the electromagnetic transmission spectrum.

  19. Electromagnetics

    CERN Document Server

    Rothwell, Edward J

    2009-01-01

    Introductory concepts Notation, conventions, and symbology The field concept of electromagneticsThe sources of the electromagnetic field Problems Maxwell's theory of electromagnetism The postulate Maxwell's equations in moving frames The Maxwell-Boffi equations Large-scale form of Maxwell's equationsThe nature of the four field quantities Maxwell's equations with magnetic sources Boundary (jump) conditions Fundamental theorems The wave nature of the electromagnetic field ProblemsThe static electromagnetic field Static fields and steady currents ElectrostaticsMagnetostatics Static field theorem

  20. A metasurface carpet cloak for electromagnetic, acoustic and water waves.

    Science.gov (United States)

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-29

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.

  1. Enhanced transmission of electromagnetic waves through 1D plasmonic crystals.

    Science.gov (United States)

    So, Jin-Kyu; Jung, Hoe-Cheon; Min, Sun-Hong; Jang, Kyu-Ha; Bak, Seung-Ho; Park, Gun-Sik

    2010-09-13

    Transmission of electromagnetic waves through thick perfect conducting slabs perforated by one-dimensional arrays of rectangular holes was studied experimentally in the microwave frequency range. The observed thickness-dependent transmission clearly exhibits the evanescent and propagating nature of the involved electromagnetic excitations on the considered structures, which are effective surface plasmons and localized waveguide resonances, respectively. The 1D crystals showing transmission based on localized resonances further manifests the frequency-dependent effective refractive index depending on the filling ratio of the holes and accompanies resonant guided wave propagation.

  2. Cell therapy for spinal cord injury informed by electromagnetic waves.

    Science.gov (United States)

    Finnegan, Jack; Ye, Hui

    2016-10-01

    Spinal cord injury devastates the CNS, besetting patients with symptoms including but not limited to: paralysis, autonomic nervous dysfunction, pain disorders and depression. Despite the identification of several molecular and genetic factors, a reliable regenerative therapy has yet to be produced for this terminal disease. Perhaps the missing piece of this puzzle will be discovered within endogenous electrotactic cellular behaviors. Neurons and stem cells both show mediated responses (growth rate, migration, differentiation) to electromagnetic waves, including direct current electric fields. This review analyzes the pathophysiology of spinal cord injury, the rationale for regenerative cell therapy and the evidence for directing cell therapy via electromagnetic waves shown by in vitro experiments.

  3. Electromagnetic Wave Propagation Models for Multiple-Diffraction Scenarios

    Directory of Open Access Journals (Sweden)

    Mehmet Barış TABAKCIOĞLU

    2014-04-01

    Full Text Available Electromagnetic wave propagation models have been used for coverage estimation and field prediction at the receiver to make more reliable and efficient digital broadcasting systems. Propagation models can be classified into two groups as numerical and ray tracing based models. There is a tradeoff between computation time and accuracy of field prediction among electromagnetic wave propagation models. Although numerical models predict accurately, it requires more computation times. Ray tracing based models predicts the field strength less accurately with lower computation time. Many propagation models have been developed to provide optimum solution for accuracy and computation time

  4. Study of a condition for the mode conversion from purely perpendicular electrostatic waves to electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Kalaee, Mohammad Javad, E-mail: mjkalaee@ut.ac.ir [Space Physics Group, Institute of Geophysics, University of Tehran (Iran, Islamic Republic of); Katoh, Yuto, E-mail: yuto@stpp.gp.tohoku.ac.jp [Department of Geophysics, Graduate School of Science, Tohoku University (Japan)

    2016-07-15

    One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma waves (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.

  5. Propagation of Electromagnetic Waves in Extremely Dense Media

    CERN Document Server

    Masood, Samina

    2016-01-01

    We study the propagation of electromagnetic (EM) waves in extremely dense exotic systems with very unique properties. These EM waves develop a longitudinal component due to its interaction with the medium. Renormalization scheme of QED is used to understand the propagation of EM waves in both longitudinal and transverse directions. The propagation of EM waves in a quantum statistically treatable medium affects the properties of the medium itself. The electric permittivity and the magnetic permeability of the medium are modified and influence the related behavior of the medium. All the electromagnetic properties of a medium become a function of temperature and chemical potential of the medium. We study in detail the modifications of electric permittivity and magnetic permeability and other related properties of a medium in the superdense stellar objects.

  6. An investigation into underground navigation using electromagnetic waves

    CERN Document Server

    Tillema, N J

    2000-01-01

    findings. The lateral wave starts at the source underground, travels to the boundary, follows the air-ground boundary and then propagates back into the ground to the receiver antenna. As the wave travels a significant part of its path in air, it was less susceptible to irregularities underground. Measurement of the phase has shown it to be sensitive to errors caused by reflections. This was the reason why reliable information of the phase was not always available during the measurements. The field trials have shown the possibility of using electromagnetic waves to track a moving transmitter underground. Any system that estimates the underground displacement of the transmitter should have two or more receiver antennas. The experiments have shown a possible accuracy of such a system of approximately 2 m or less. This thesis explores the possibility of measuring the movement of an underground transmitter using electromagnetic waves. The displacement of the transmitter was estimated based on the magnitude and pha...

  7. MOF-Derived Porous Co/C Nanocomposites with Excellent Electromagnetic Wave Absorption Properties.

    Science.gov (United States)

    Lü, Yinyun; Wang, Yiting; Li, Hongli; Lin, Yuan; Jiang, Zhiyuan; Xie, Zhaoxiong; Kuang, Qin; Zheng, Lansun

    2015-06-24

    Composites incorporating ferromagnetic metal nanopartices into a highly porous carbon matrix are promising as electromagnetic wave absorption materials. Such special composite nanomaterials are potentially prepared by the thermal decomposition of metal-organic framework (MOF) materials under controlled atmospheres. In this study, using Co-based MOFs (Co-MOF, ZIF-67) as an example, the feasibility of this synthetic strategy was demonstrated by the successful fabrication of porous Co/C composite nanomaterials. The atmosphere and temperature for the thermal decomposition of MOF precursors were crucial factors for the formation of the ferromagnetic metal nanopartices and carbon matrix in the porous Co/C composites. Among the three Co/C composites obtained at different temperatures, Co/C-500 obtained at 500 °C exhibited the best performance for electromagnetic wave absorption. In particular, the maximum reflection loss (RL) of Co/C-500 reached -35.3 dB, and the effective absorption bandwidth (RL ≤ -10 dB) was 5.80 GHz (8.40 GHz-14.20 GHz) corresponding to an absorber thickness of 2.5 mm. Such excellent electromagnetic wave absorption properties are ascribed to the synergetic effects between the highly porous structure and multiple components, which significantly improved impedance matching.

  8. Wave propagation and impact in composite materials

    Science.gov (United States)

    Moon, F. C.

    1975-01-01

    Anisotropic waves in composites are considered, taking into account wave speeds, wave surfaces, flexural waves in orthotropic plates, surface waves, edge waves in plates, and waves in coupled composite plates. Aspects of dispersion in composites are discussed, giving attention to pulse propagation and dispersion, dispersion in rods and plates, dispersion in a layered composite, combined material and structural dispersion, continuum theories for composites, and variational methods for periodic composites. The characteristics of attenuation and scattering processes are examined and a description is given of shock waves and impact problems in composites. A number of experiments are also reported.

  9. Mathematical models for dispersive electromagnetic waves: an overview

    OpenAIRE

    Cassier, Maxence; Joly, Patrick; Kachanovska, Maryna

    2017-01-01

    In this work, we investigate mathematical models for electromagnetic wave propagation in dispersive isotropic media. We emphasize the link between physical requirements and mathematical properties of the models. A particular attention is devoted to the notion of non-dissipativity and passivity. We consider successively the case of so-called local media and general passive media. The models are studied through energy techniques, spectral theory and dispersion analysis of plane waves. For makin...

  10. Cellular and molecular effects of electromagnetic radiation and sonic waves

    OpenAIRE

    Patricia Froes Meyer; Oscar Ariel Ronzio; Adenilson de Souza da Fonseca; Sebastiao David Santos-Filho; Mario Bernardo-Filho

    2013-01-01

    Electromagnetic radiation (in the form of pulsed magnetic fields, radiofrequency and intense pulsed light) and mechanical agents (such as sonic waves) have been used in physical therapy. The aim of this study was to assess the effects of low-intensity magnetic fields, sonic and radiofrequency waves, and intense pulsed light on the survival of Escherichia coli cultures and on the electrophoretic mobility of plasmid DNA. Exponentially growing E. coli AB1157 cultures and plasmid DNA samples were...

  11. Through casing weak electromagnetic wave signal detection and application

    Science.gov (United States)

    Li, Hui; Zhu, Xi-Fang; Cui, Cui-Mei

    2017-07-01

    Electromagnetic measurement technology is an important method for instrument parameters calibration, detection performance evaluation and complex system theory verification. In this paper, self-adaptive finite element method has been used to compute and analyze the weak electromagnetic wave signal, which is produced by changing electrode structure, transmitting frequency and antenna spacing of the through casing electromagnetic measurement tool. Numerical simulation results show that the detection depth of the tool can be influenced by the electrode structure can have the influence on, the resolution of high-resistivity and low-resistivity formation can be improved by transmitting frequency, the detection accuracy and detection depth of the through casing electromagnetic measurement tool can be influenced by the change of antenna spacing.

  12. Rotatable illusion media for manipulating terahertz electromagnetic waves

    National Research Council Canada - National Science Library

    Zang, XiaoFei; Li, Zhou; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing; Li, Li; Wang, XiaoBin

    2013-01-01

    Based on composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter...

  13. Molding acoustic, electromagnetic and water waves with a single cloak.

    Science.gov (United States)

    Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

    2015-06-09

    We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves.

  14. Molding acoustic, electromagnetic and water waves with a single cloak

    KAUST Repository

    Xu, Jun

    2015-06-09

    We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. © 2015, Nature Publishing Group. All rights reserved.

  15. Negative electromagnetic plane-wave force in gain media.

    Science.gov (United States)

    Webb, Kevin J; Shivanand

    2011-11-01

    It is shown that a uniform electromagnetic plane wave can exert a negative force on a homogeneous medium with gain when there is no component of the electric field in that direction. A physical interpretation for this force is given, along with an estimate of the strength achievable in an experiment.

  16. FDTD Modelling of Electromagnetic waves in Stratified Medium ...

    African Journals Online (AJOL)

    The technique is an adaptation of the finite-difference time domain (FDTD) approach usually applied to model electromagnetic wave propagation. In this paper a simple 2D implementation of FDTD algorithm in mathematica environment is presented. Source implementation and the effect of conductivity on the incident field ...

  17. Three-dimensional accelerating electromagnetic waves.

    Science.gov (United States)

    Bandres, Miguel A; Alonso, Miguel A; Kaminer, Ido; Segev, Mordechai

    2013-06-17

    We present a general theory of three-dimensional non-paraxial spatially-accelerating waves of the Maxwell equations. These waves constitute a two-dimensional structure exhibiting shape-invariant propagation along semicircular trajectories. We provide classification and characterization of possible shapes of such beams, expressed through the angular spectra of parabolic, oblate and prolate spheroidal fields. Our results facilitate the design of accelerating beams with novel structures, broadening scope and potential applications of accelerating beams.

  18. Electromagnetic wave dynamics in matter-wave superradiant scattering.

    Science.gov (United States)

    Deng, L; Payne, M G; Hagley, E W

    2010-02-05

    We present a small-signal wave propagation theory on matter-wave superradiant scattering. We show, in a longitudinally excited condensate, that the backward-propagating, superradiantly generated optical field propagates with ultraslow group velocity and that the small-signal gain profile has a Bragg resonance. We further show a unidirectional suppression of optical superradiant scattering, and explain why matter-wave superradiance can occur only when the pump laser is red detuned. This is the first analytical theory on field propagation in matter-wave superradiance that can explain all matter-wave superradiance experiments to date that used a single-frequency, long-pulse, red-detuned laser.

  19. Reflection of electromagnetic waves at a biaxial-isotropic interface

    Science.gov (United States)

    Njoku, E. G.

    1983-01-01

    The reflection of electromagnetic waves at a plane boundary between isotropic and biaxial media has been investigated using the kDB approach. The general case has been considered in which the principal dielectric axes of the biaxial medium are oriented at an arbitrary angle to the normal of the plane boundary. In general, two characteristic waves propagate in the biaxial medium, leading to coupling of vertical and horizontal polarizations in the reflected waves. Some special cases are illustrated. The results have applications to problems in remote sensing and integrated optics.

  20. Absorption of electromagnetic and gravitational waves by Kerr black holes

    Directory of Open Access Journals (Sweden)

    Luiz C.S. Leite

    2017-11-01

    Full Text Available We calculate the absorption cross section for planar waves incident upon Kerr black holes, and present a unified picture for scalar, electromagnetic and gravitational waves. We highlight the spin-helicity effect that arises from a coupling between the rotation of the black hole and the helicity of a circularly-polarized wave. For the case of on-axis incidence, we introduce an extended ‘sinc approximation’ to quantify the spin-helicity effect in the strong-field regime.

  1. Transmission of electromagnetic waves through sub-wavelength channels

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Luo, Yu; Mortensen, Asger

    2010-01-01

    We propose a method of tunneling electromagnetic (EM) waves through a channel with sub-wavelength cross section. By filling the channel with high-ε isotropic material and implementing two matching layers with uniaxial metamterial substrates, the guided waves can go through the narrow channel...... without being cut off, as if it has just passed through the original empty waveguide. Both the magnitude and phase information of the EM fields can be effectively restored after passing this channel, regardless of the polarization of the incoming wave. The performance of this subwavelength channel, which...

  2. Transmission of electromagnetic waves through sub-wavelength channels.

    Science.gov (United States)

    Zhang, Jingjing; Luo, Yu; Mortensen, Niels Asger

    2010-02-15

    We propose a method of tunneling electromagnetic (EM) waves through a channel with sub-wavelength cross section. By filling the channel with high-epsilon isotropic material and implementing two matching layers with uniaxial metamterial substrates, the guided waves can go through the narrow channel without being cut off, as if it has just passed through the original empty waveguide. Both the magnitude and phase information of the EM fields can be effectively restored after passing this channel, regardless of the polarization of the incoming wave. The performance of this sub-wavelength channel, which is designed with coordinate transformation methodology, is studied theoretically and numerically.

  3. Precision cosmology from future lensed gravitational wave and electromagnetic signals.

    Science.gov (United States)

    Liao, Kai; Fan, Xi-Long; Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong

    2017-10-27

    The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10 4 -10 5 gravitational wave detections per year, 50-100 of which will be lensed. Here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. We demonstrate that just 10 such systems can provide a Hubble constant uncertainty of 0.68% for a flat lambda cold dark matter universe in the era of third-generation ground-based detectors.

  4. Electron beam injection during active experiments. I - Electromagnetic wave emissions

    Science.gov (United States)

    Winglee, R. M.; Kellogg, P. J.

    1990-01-01

    The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

  5. Multiple scattering of electromagnetic waves by rain

    Science.gov (United States)

    Tsolakis, A.; Stutzman, W. L.

    1982-01-01

    As the operating frequencies of communications systems move higher into the millimeter wave region, the effects of multiple scattering in precipitation media become more significant. In this paper, general formulations are presented for single, first-order multiple, and complete multiple scattering. Included specifically are distributions of particle size, shape, and orientation angle, as well as variation in the medium density along the direction of wave propagation. Calculations are performed for rain. It is shown that the effects of higher-order scattering are not noticeable in either attenuation or channel isolation on a dual-polarized system until frequencies of about 30 GHz are reached. The complete multiple-scattering formulation presented gives accurate results at high millimeter wave frequencies as well as including realistic medium parameter distributions. Furthermore, it is numerically efficient.

  6. Electromagnetic Waves Broadcast by a VCR.

    Science.gov (United States)

    Brown, Michael H.

    1996-01-01

    Presents experiments that use a video cassette recorder (VCR) to demonstrate polarization of radio waves using two dipole antennas and a spark gap transmitter tuned to a frequency of either 60-66 MHz or 66-72 MHz with wavelengths of 5 or 4.3 meters, close to the wavelengths of the original work done by Heinrich Hertz. (JRH)

  7. Success of electromagnetic shock wave lithotripter asmonotherapy ...

    African Journals Online (AJOL)

    Objectives: To evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renalstones larger than 2 cm without ureteral stenting. Hence, if our study result demonstrates acceptable successand safety, we can recommend ESWL as a treatment option for patients with large renal calculi. Subjects and ...

  8. Electromagnetic wave scattering from some vegetation samples

    Science.gov (United States)

    Karam, Mostafa A.; Fung, Adrian K.; Antar, Yahia M.

    1988-01-01

    For an incident plane wave, the field inside a thin scatterer (disk and needle) is estimated by the generalized Rayleigh-Gans (GRG) approximation. This leads to a scattering amplitude tensor equal to that obtained via the Rayleigh approximation (dipole term) with a modifying function. For a finite-length cylinder the inner field is estimated by the corresponding field for the same cylinder of infinite lenght. The effects of different approaches in estimating the field inside the scatterer on the backscattering cross section are illustrated numerically for a circular disk, a needle, and a finite-length cylinder as a function of the wave number and the incidence angle. Finally, the modeling predictions are compared with measurements.

  9. Magnesiothermic reduction of rice husk ash for electromagnetic wave adsorption

    Science.gov (United States)

    Liu, Shu-Ting; Yan, Kang-kang; Zhang, Yuan hu; Jin, Shi-di; Ye, Ying; Chen, Xue-Gang

    2015-11-01

    The increase in electromagnetic pollution due to the extensive exploitation of electromagnetic (EM) waves in modern technology creates correspondingly urgent need for developing effective EM wave absorbers. In this study, we carried out the magnesiothermic reduced the rice husk ash under different temperatures (400-800 °C) and investigated the electromagnetic wave adsorption of the products. The EM absorbing for all samples are mainly depend on the dielectric loss, which is ascribed to the carbon and silicon carbide content. RA samples (raw rice husk ashed in air and was magesiothermic reduced in different temperatures) exhibit poor dielectric properties, whereas RN samples (raw rice husk ashed in nitrogen and was magesiothermic reduced in different temperatures) with higher content of carbon and silicon carbide display considerable higher dielectric loss values and broader bandwidth for RL<-5 dB and -10 dB. For RN samples, the maximum bandwidth for -5 dB and -10 dB decrease with carbon contents, while the optimum thickness decrease with increasing SiC content. The optimum thickness of RN400-800 for EM absorption is 1.5-2.0 mm, with maximum RL of between -28.9 and -68.4 dB, bandwidth of 6.7-13 GHz for RL<-5 dB and 3.2-6.2 GHz for RL<-10 dB. The magnesiothermic reduction will enhance the potential application of rice husk ash in EM wave absorption and the samples benefited from low bulk density and low thickness. With the advantages of light-weight, high EM wave absorption, low cost, RN400-800 could be promising candidates for light-weight EM wave absorption materials over many conventional EM wave absorbers.

  10. Electromagnetic wave scattering on imperfect cloaking devices

    Directory of Open Access Journals (Sweden)

    Isić G.

    2008-01-01

    Full Text Available Cloaking devices based on the coordinate transform approach enable, in principle, a perfect concealment of a region in space provided that the material composing the cloaking shell meets certain criteria. To achieve ideal cloaking it is necessary that the shell material parameters have singular values on the surface bounding the cloaked region which is unphysical. In this paper we assume finite values of cloak parameters and apply the scattering theory formalism to give an estimate of the overall performance of an 'imperfect' cloak. We perform full-wave numerical calculations and use our theoretical results to discuss them.

  11. Highly efficient proteolysis accelerated by electromagnetic waves for Peptide mapping.

    Science.gov (United States)

    Chen, Qiwen; Liu, Ting; Chen, Gang

    2011-09-01

    Proteomics will contribute greatly to the understanding of gene functions in the post-genomic era. In proteome research, protein digestion is a key procedure prior to mass spectrometry identification. During the past decade, a variety of electromagnetic waves have been employed to accelerate proteolysis. This review focuses on the recent advances and the key strategies of these novel proteolysis approaches for digesting and identifying proteins. The subjects covered include microwave-accelerated protein digestion, infrared-assisted proteolysis, ultraviolet-enhanced protein digestion, laser-assisted proteolysis, and future prospects. It is expected that these novel proteolysis strategies accelerated by various electromagnetic waves will become powerful tools in proteome research and will find wide applications in high throughput protein digestion and identification.

  12. Controlling Gigahertz and Terahertz Surface Electromagnetic Waves with Metamaterial Resonators

    Directory of Open Access Journals (Sweden)

    W.-C. Chen

    2011-12-01

    Full Text Available We computationally and experimentally investigate the use of metamaterial resonators as bandpass filters and other components that enable control of guided surface electromagnetic waves. The guided surface electromagnetic wave propagates on a planar Goubau line, launched via a coplanar waveguide coupler with 50Ω impedance. Experimental samples targeted for either microwave or terahertz frequencies are measured and shown to be in excellent agreement with simulations. Metamaterial elements are designed to absorb energy only of the planar Goubau line and yield narrow-band resonances with relatively high quality factors. Two independent configurations of coupled metamaterial elements are demonstrated that modify the otherwise flat transmission spectrum of the planar Goubau line. By physically shunting the capacitive gaps of the coupled metamaterial elements, we demonstrate the potential for a large dynamic range in transmissivity, suggesting the use of this configuration for high-bandwidth terahertz communications.

  13. Division of the momentum of electromagnetic waves in linear media into electromagnetic and material parts.

    Science.gov (United States)

    Saldanha, Pablo L

    2010-02-01

    It is proposed a natural and consistent division of the momentum of electromagnetic waves in linear, non-dispersive and non-absorptive dielectric and magnetic media into material and electromagnetic parts. The material part is calculated using directly the Lorentz force law and the electromagnetic momentum density has the form epsilon(0)E x B, without an explicit dependence on the properties of the media. The consistency of the treatment is verified through the obtention of a correct momentum balance equation in many examples and showing the compatibility of the division with the Einstein's theory of relativity by the use of a gedanken experiment. An experimental prediction for the radiation pressure on mirrors immersed in linear dielectric and magnetic media is also made.

  14. Electromagnetic wave theory for boundary-value problems an advanced course on analytical methods

    CERN Document Server

    Eom, Hyo J

    2004-01-01

    Electromagnetic wave theory is based on Maxwell's equations, and electromagnetic boundary-value problems must be solved to understand electromagnetic scattering, propagation, and radiation. Electromagnetic theory finds practical applications in wireless telecommunications and microwave engineering. This book is written as a text for a two-semester graduate course on electromagnetic wave theory. As such, Electromagnetic Wave Theory for Boundary-Value Problems is intended to help students enhance analytic skills by solving pertinent boundary-value problems. In particular, the techniques of Fourier transform, mode matching, and residue calculus are utilized to solve some canonical scattering and radiation problems.

  15. Detecting electromagnetic cloaks using backward-propagating waves

    KAUST Repository

    Salem, Mohamed

    2011-08-01

    A novel approach for detecting transformation-optics invisibility cloaks is proposed. The detection method takes advantage of the unusual backward-propagation characteristics of recently reported beams and pulses to induce electromagnetic scattering from the cloak. Even though waves with backward-propagating energy flux cannot penetrate the cloaking shell and interact with the cloaked objects (i.e., they do not make the cloaked object visible), they provide a mechanism for detecting the presence of cloaks. © 2011 IEEE.

  16. Paraxial theory of electromagnetic waves in plane inhomogeneous media.

    Science.gov (United States)

    Hacyan, Shahen

    2010-09-01

    The problem of electromagnetic waves propagating in inhomogeneous media is formulated within the paraxial approximation. The analysis is restricted to a medium with a plane and smooth inhomogeneity. The general form of a Gaussian beam is obtained in terms of the permittivity and permeability of the medium. Particular attention is paid to the case of internal reflection, where a short-wavelength approximation breaks down; a possible treatment of the problem is proposed. A simple model is worked out to illustrate the formalism.

  17. Electromagnetic waves in a model with Chern-Simons potential.

    Science.gov (United States)

    Pis'mak, D Yu; Pis'mak, Yu M; Wegner, F J

    2015-07-01

    We investigated the appearance of Chern-Simons terms in electrodynamics at the surface or interface of materials. The requirement of locality, gauge invariance, and renormalizability in this model is imposed. Scattering and reflection of electromagnetic waves in three different homogeneous layers of media is determined. Snell's law is preserved. However, the transmission and reflection coefficient depend on the strength of the Chern-Simons interaction (connected with Hall conductance), and parallel and perpendicular components are mixed.

  18. Mathematical models for dispersive electromagnetic waves: An overview

    OpenAIRE

    Cassier, Maxence; Joly, Patrick; Kachanovska, Maryna

    2017-01-01

    International audience; In this work, we investigate mathematical models for electromagnetic wave propagation in dispersive isotropic media. We emphasize the link between physical requirements and mathematical properties of the models. A particular attention is devoted to the notion of non-dissipativity and passivity. We consider successively the case of so-called local media and general passive media. The models are studied through energy techniques, spectral theory and dispersion analysis o...

  19. Diffraction of electromagnetic waves by a rectangular wedge structure

    Science.gov (United States)

    Makarov, G. I.; Sozonov, A. P.

    A theoretical problem of electromagnetic wave diffraction in a system of two rectangular wedges is examined: a perfectly conducting wedge and a wedge with finite relative permittivity, the two wedges having a common face. For the Fourier component of the diffraction field, a shifting Riemann boundary value problem is obtained. This problem is reduced to a convolution-type integral equation for the semiaxis, with the kernel taking the form of the sum of the difference and regular kernels.

  20. Stimulated electromagnetic emission polarization under different polarizations of pump waves

    OpenAIRE

    E. D. Tereshchenko; R. Y. Yurik; Baddeley, L.

    2015-01-01

    The results of investigations into the stimulated electromagnetic emission (SEE) polarization under different modes of the pump wave polarization are presented. The present results were obtained in November 2012 during a heating campaign utilizing the SPEAR (Space Plasma Exploration by Active Radar) heating facility, transmitting in both O- and X-mode polarization, and a PGI (Polar Geophysical Institute) radio interferometer capable of recording the polarization of the recei...

  1. Electromagnetic wave extinction within a forested canopy

    Science.gov (United States)

    Karam, M. A.; Fung, A. K.

    1989-01-01

    A forested canopy is modeled by a collection of randomly oriented finite-length cylinders shaded by randomly oriented and distributed disk- or needle-shaped leaves. For a plane wave exciting the forested canopy, the extinction coefficient is formulated in terms of the extinction cross sections (ECSs) in the local frame of each forest component and the Eulerian angles of orientation (used to describe the orientation of each component). The ECSs in the local frame for the finite-length cylinders used to model the branches are obtained by using the forward-scattering theorem. ECSs in the local frame for the disk- and needle-shaped leaves are obtained by the summation of the absorption and scattering cross-sections. The behavior of the extinction coefficients with the incidence angle is investigated numerically for both deciduous and coniferous forest. The dependencies of the extinction coefficients on the orientation of the leaves are illustrated numerically.

  2. Particle Dynamics under Quasi-linear Interaction with Electromagnetic Waves

    Energy Technology Data Exchange (ETDEWEB)

    Castejon, F.; Eguilior, S.

    2003-07-01

    Langevin equations for quasi-linear wave particle interaction are obtained taking advantage of the unique vocal equivalence between Fokker-Plank equation and the former ones. Langevin equations are solved numerically and, hence, the evolution of a single particle embedded in an electromagnetic field in momentum space is obtained. The equations are relativistic and valid for any wave. It is also shown that the stochastic part of the equations is negligible in comparison with the deterministic term, except for the momentum to the resonance condition for the main parallel refractive index. (Author) 24 refs.

  3. Reflection and transmission of electromagnetic waves at a temporal boundary.

    Science.gov (United States)

    Xiao, Yuzhe; Maywar, Drew N; Agrawal, Govind P

    2014-02-01

    We consider propagation of an electromagnetic (EM) wave through a dynamic optical medium whose refractive index varies with time. Specifically, we focus on the reflection and transmission of EM waves from a temporal boundary and clarify the two different physical processes that contribute to them. One process is related to impedance mismatch, while the other results from temporal scaling related to a sudden change in the speed of light at the temporal boundary. Our results show that temporal scaling of the electric field must be considered for light propagation in dynamic media. Numerical solutions of Maxwell's equations are in full agreement with our theory.

  4. Spin-electromagnetic waves in planar multiferroic multilayers

    Science.gov (United States)

    Nikitin, Andrey A.; Ustinov, Alexey B.; Vitko, Vitalii V.; Nikitin, Alexey A.; Kondrahov, Alexandr V.; Pirro, P.; Lähderanta, E.; Kalinikos, Boris A.; Hillebrands, B.

    2017-07-01

    A general electrodynamic theory is developed for dispersion characteristics of spin-electromagnetic waves (SEWs) propagating in multiferroic multilayers. The derivation is based on the full set of Maxwell's equations taking into account retardation effects. The multilayers are considered to be composed of an infinite number of ferrite and ferroelectric layers having arbitrary thicknesses, as well as arbitrary magnetic and electric parameters. As an example, spectra of SEWs are calculated and analyzed for a heterostructure containing two thin ferrite films separated by a thin ferroelectric film. An electric field tunability of the SEW dispersion characteristics at gigahertz frequencies is shown, providing an efficient control of SEW wave-numbers important for applications.

  5. Influence of electromagnetic SHF-waves on motility of tubifex

    Directory of Open Access Journals (Sweden)

    I. K. Smolyarenko

    2005-02-01

    Full Text Available We investigated influence of electromagnetic superhigh frequency (SHF waves (10 hHz on mechanical parameters of motility of bunch tubifex (1300 - 1500 units at a different load and sequence of its mechanical stimulation. Is shown, that after a пот-thermal waveirradiation (1 MVt/sm2 latency and forward front of mechanograms is increased on 5 - 10 %, amplitude and duration of the answers simultaneously decreases. The maximal mass, which can lift single unit tubifex is decreased. The capacity of single unit is reduced on the average about 80 %. The authors make conclusion about temporary negative influence SHF-waves on simple biological systems.

  6. Modeling and design for electromagnetic surface wave devices

    Science.gov (United States)

    La Spada, Luigi; Haq, Sajad; Hao, Yang

    2017-09-01

    A great deal of interest has reemerged recently in the study of surface waves. The possibility to control and manipulate electromagnetic wave propagations at will opens many new research areas and leads to lots of novel applications in engineering. In this paper, we will present a comprehensive modeling and design approach for surface wave cloaks, based on graded-refractive-index materials and the theory of transformation optics. It can be also applied to any other forms of surface wave manipulation, in terms of amplitude and phase. In this paper, we will present a general method to illustrate how this can be achieved from modeling to the final design. The proposed approach is validated to be versatile and allows ease in manufacturing, thereby demonstrating great potential for practical applications.

  7. Obliquely Propagating Electromagnetic Waves in Magnetized Kappa Plasmas

    Science.gov (United States)

    Gaelzer, R.

    2015-12-01

    The effects of velocity distribution functions (VDFs) that exhibit a power-law dependence on the high-energy tail have been the subjectof intense research by the space plasma community. Such functions, known as kappa or superthermal distributions, have beenfound to provide a better fitting to the VDF measured by spacecraft in the solar wind. One of the problems that is being addressed on this new light is the temperature anisotropy of solar wind protons and electrons. An anisotropic kappa VDF contains a large amount of free energy that can excite waves in the solar wind. Conversely, the wave-particle interaction is important to determine the shape of theobserved particle distributions.In the literature, the general treatment for waves excited by (bi-)Maxwellian plasmas is well-established. However, for kappa distributions, either isotropic or anisotropic, the wave characteristics have been studied mostly for the limiting cases of purely parallel or perpendicular propagation. Contributions for the general case of obliquely-propagating electromagnetic waves have been scarcely reported so far. The absence of a general treatment prevents a complete analysis of the wave-particle interaction in kappa plasmas, since some instabilities, such as the firehose, can operate simultaneously both in the parallel and oblique directions.In a recent work [1], we have obtained expressions for the dielectric tensor and dispersion relations for the low-frequency, quasi-perpendicular dispersive Alfvén waves resulting from a kappa VDF. In the present work, we generalize the formalism introduced by [1] for the general case of electrostatic and/or electromagnetic waves propagating in a kappa plasma in any frequency range and for arbitrary angles.We employ an isotropic distribution, but the methods used here can be easily applied to more general anisotropic distributions,such as the bi-kappa or product-bi-kappa. [1] R. Gaelzer and L. F. Ziebell, Journal of Geophysical Research 119, 9334

  8. Descriptive Study of Electromagnetic Wave Distribution for Various Seating Positions: Using Digital Textbooks

    Science.gov (United States)

    Seomun, GyeongAe; Kim, YoungHwan; Lee, Jung-Ah; Jeong, KwangHoon; Park, Seon-A; Kim, Miran; Noh, Wonjung

    2014-01-01

    To better understand environmental electromagnetic wave exposure during the use of digital textbooks by elementary school students, we measured numeric values of the electromagnetic fields produced by tablet personal computers (TPCs). Specifically, we examined the distribution of the electromagnetic waves for various students' seating positions in…

  9. A STUDY OF NONLINEAR PHENOMENA IN THE PROPAGATION OF ELECTROMAGNETIC WAVES IN A WEAKLY IONIZED GAS.

    Science.gov (United States)

    This paper is a study of nonlinear phenomena in the propagation of electromagnetic waves in a weakly ionized gas externally biased with a magneto...static field. The present study is restricted to the nonlinear phenomena arising from the interaction of electromagnetic waves in the ionized gas. The...the propagation of electromagnetic waves in the ionized gas, and also on the reflection of waves from an ionized gas semi-infinite extent. (Author)

  10. Electron States and Quasienergy Spectrum of the Graphene Exposed to the Electromagnetic Wave

    OpenAIRE

    S.V. Kryuchkov; E.I. Kukhar’; O.S. Nikitina

    2013-01-01

    The effective spectrum and wave functions of electron states in graphene under the electromagnetic wave with circular polarization are found. The band gap in the graphene spectrum induced by the electromagnetic wave is calculated. Occurrence of such gap is shown to have the nature of the parametric resonance. The effective energy of the electron state in graphene is proved to be the energy averaged over the period of the electromagnetic wave.

  11. Early electromagnetic waves from earthquake rupturing: I. theoretical formulations

    Science.gov (United States)

    Gao, Yongxin; Chen, Xiaofei; Hu, Hengshan; Zhang, Jie

    2013-03-01

    Earthquake taking place in a fluid-saturated porous medium can generate electromagnetic (EM) waves because of the electrokinetic effect. These generated EM waves arrive at a distant observatory much earlier than the seismic waves because their velocities are much faster than those of the seismic waves. They may explain the early EM signals which have been detected before the detection of the seismic waves after the occurrences of earthquakes. In this study, we attempt to analyse such a kind of early EM signals induced by an earthquake because of the electrokinetic effect. The earthquake is assumed to be a fault slip and is modelled by a moment tensor point source. With Pride's equations quantifying the coupling between seismic and EM waves, we first present a real-axis integration (RAI) algorithm to calculate the seismoelectric wavefields in a layered porous formation. Although full waveforms can be calculated by such a RAI technique, individual waves cannot be easily separated from the full waveforms. The need to compute the individual waves is eminent for the purpose of investigating the early EM waves, because these EM waves are usually several orders weaker than and are masked by the EM signals accompanying the seismic waves in the full waveforms. Therefore, we further develop a branch-cut integration (BCI) algorithm, by transforming the original wavenumber integral along the real axis in the complex wavenumber plane for the RAI technique to a sum of integrals along the vertical branch cuts and the residues of the poles. For performing the integrations along the vertical branch cuts, determination of the Riemann sheets are explained and displayed. Finally, the seismoelectric wavefields are represented in forms allowing calculating individual waves.

  12. The scattering of electromagnetic waves from turbulent plasmas

    Science.gov (United States)

    Ram, A. K.; Hizanidis, K.

    2017-10-01

    In fusion devices, radio frequency (RF) electromagnetic waves encounter turbulent plasmas along their path from the excitation structures to the core of the plasma. In order to optimize heating and current drive by the RF waves, it is necessary to understand the effect of the density turbulence on the propagation characteristics of the waves. A common approach towards quantifying the effects of turbulence is the Kirchhoff technique. Here the wave fields and their normal derivatives are evaluated at a surface separating two different densities using physical optics. The fields at any point on this surface are approximated to be the same as the fields on a tangent plane at that point. Using the Kirchhoff technique, we show that turbulence can lead to changes in the propagation vector and polarization of the waves, side-scattering, and coupling between different plasma waves. This affects the spatial uniformity of power flow into the plasma. Full wave analytical calculations and numerical simulations confirm these physical results. The theory applies to all RF waves, irrespective of their frequency, and allows for arbitrary plasma density variations. Supported by DoE Grant DE-FG02-91ER-54109 and in part by the Hellenic National Programme on Controlled Thermonuclear Fusion associated with the EUROfusion Consortium.

  13. Electromagnetic shielding effectiveness of 3D printed polymer composites

    Science.gov (United States)

    Viskadourakis, Z.; Vasilopoulos, K. C.; Economou, E. N.; Soukoulis, C. M.; Kenanakis, G.

    2017-12-01

    We report on preliminary results regarding the electromagnetic shielding effectiveness of various 3D printed polymeric composite structures. All studied samples were fabricated using 3D printing technology, following the fused deposition modeling approach, using commercially available filaments as starting materials. The electromagnetic shielding performance of the fabricated 3D samples was investigated in the so called C-band of the electromagnetic spectrum (3.5-7.0 GHz), which is typically used for long-distance radio telecommunications. We provide evidence that 3D printing technology can be effectively utilized to prepare operational shields, making them promising candidates for electromagnetic shielding applications for electronic devices.

  14. Parametric instabilities of circularly polarized large-amplitude dispersive Alfven waves: excitation of parallel-propagating electromagnetic daughter waves

    Energy Technology Data Exchange (ETDEWEB)

    Vinas, A.F.; Goldstein, M.L. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center)

    1991-08-01

    The parametric decay and modulational instabilities of a large-amplitude circularly polarized dispersive Alfven wave are investigated. The treatment is more general than that of previous derivations based on the two-fluid equations in that allowance is made for propagation of the unstable daughter waves at arbitrary angles to the background magnetic field, although the main concern is the exploration of new aspects of propagation parallel to the DC magnetic field. In addition to the well-known coupling of pump waves to electrostatic daughter waves, a new parametric channel is found where the pump wave couples directly to electromagnetic daughter waves. The growth rate of the electromagnetic instability increases monotonically with increasing pump wave amplitude. Analysis confirms that, for decay, the dominant process is coupling to electrostatic daughter waves, at least for parallel propagation. For modulation, the coupling to electromagnetic daughter waves usually dominates, suggesting that the parametric modulational instability is really an electromagnetic phenomena. (author).

  15. Low frequency electromagnetic radiation from gravitational waves generated by neutron stars

    Science.gov (United States)

    Jones, Preston; Gretarsson, Andri; Singleton, Douglas

    2017-12-01

    We investigate the possibility of observing very low frequency (VLF) electromagnetic radiation produced from the vacuum by gravitational waves. We review the calculations leading to the possibility of vacuum conversion of gravitational waves into electromagnetic waves and show how this process evades the well-known prohibition against particle production from gravitational waves. Using Newman-Penrose scalars, we estimate the luminosity of this proposed electromagnetic counterpart radiation coming from gravitational waves produced by neutron star oscillations. The detection of electromagnetic counterpart radiation would provide an indirect way of observing gravitational radiation with future spacecraft missions, especially lunar orbiting probes.

  16. Self-healing structural composites with electromagnetic functionality

    Science.gov (United States)

    Plaisted, Thomas A.; Vakil Amirkhizi, Alireza; Arbelaez, Diego; Nemat-Nasser, Syrus C.; Nemat-Nasser, Sia

    2003-08-01

    We have incorporated arrays of conductive electromagnetic scattering elements such as straight copper wires and copper coils into fiber-reinforced polymer composites, resulting in materials with required structural and further electromagnetic functionality. The scattering elements provide controlled electromagnetic response for tasks such as filtering and may be used to tune the overall index of refraction of the composite. Integration of these metallic elements into traditional fiber-reinforced polymer composites has introduced other opportunities for multifunctionality in terms of self-healing, thermal transport and perhaps sensing applications. Such functionalities are the result of fiber/wire integration through textile braiding and weaving, combined with a new polymer matrix that has the ability to heal internal cracking through thermo-reversible covalent bonds. Multifunctional composites of this kind enhance the role of structural materials from mere load-bearing systems to lightweight structures of good thermo-mechanical attributes that also have electromagnetic and other functionalities.

  17. Interaction of the electromagnetic precursor from a relativistic shock with the upstream flow - I. Synchrotron absorption of strong electromagnetic waves

    Science.gov (United States)

    Lyubarsky, Yuri

    2018-02-01

    This paper is the first in the series of papers aiming to study interaction of the electromagnetic precursor waves generated at the front of a relativistic shock with the upstream flow. It is motivated by a simple consideration showing that the absorption of such an electromagnetic precursor could yield an efficient transformation of the kinetic energy of the upstream flow to the energy of accelerated particles. Taking into account that the precursor is a strong wave, in which electrons oscillate with relativistic velocities, the standard plasma-radiation interaction processes should be reconsidered. In this paper, I calculate the synchrotron absorption of strong electromagnetic waves.

  18. Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis

    Science.gov (United States)

    Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.

    2016-01-01

    Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

  19. Propagation of electromagnetic waves in stochastic helical media.

    Science.gov (United States)

    Mendez, David; Reyes, J Adrian

    2012-09-01

    We have developed a model for studying the axial propagation of elliptically polarized electromagnetic waves in a spatially random helical media. We start by writing Maxwell equations for a structurally chiral medium whose dielectric permittivities, polar, and helical angles contain both a stochastic contribution and a deterministic one. We write the electromagnetic equations into a Marcuvitz-Schwigner representation to transform them afterward in a simpler expression by using the Oseen transformation. We exhibit that in the Oseen frame the Marcuvitz-Schwigner equations turns out to be a linear vector stochastic system of differential equations with multiplicative noise. Applying to the resulting equation a formalism for treating stochastic differential equations, we find the governing equations for the first moments of the electromagnetic field amplitudes for a general autocorrelation function for the system diffractive indexes, and calculate their corresponding band structure for a particular spectral noise density. We have shown that the average resulting electromagnetic fields exhibit a decaying exponential dependence which stems from by dissipation and the presence of qualitative modifications in the band structure including a considerable widening of the band gap and the existence of new local maxima for the modes without a band gap.

  20. Scattering of electromagnetic waves from a randomly perturbed quasiperiodic surface

    Science.gov (United States)

    Shin, R. T.; Kong, J. A.

    1984-01-01

    Electromagnetic-wave scattering by a quasi-periodic surface with random perturbations (as in the remote sensing of plowed fields) is investigated analytically, applying the Kirchhoff approximation and modeling the plowed fields by means of Gaussian random variation, sinusoidal variation, and Gaussian random variation about the spatial frequency. Coherent and incoherent bistatic scattering coefficients are derived in closed form by evaluating the physical-optics integral and shown to be proportional, in the geometric-optics limit, to the occurrence probability of slopes which reflect the incident wave specularly in the direction of the scattered wave. Backscattering cross sections are plotted as functions of incidence angle for a number of cases, demonstrating the strong effect of row direction.

  1. Structural and functional polymer-matrix composites for electromagnetic applications

    Science.gov (United States)

    Wu, Junhua

    This dissertation addresses the science and technology of functional and structural polymer-matrix composite materials for electromagnetic applications, which include electromagnetic interference (EMI) shielding and low observability (Stealth). The structural composites are continuous carbon fiber epoxy-matrix composites, which are widely used for airframes. The functional composites are composites with discontinuous fillers and in both bulk and coating forms. Through composite structure variation, attractive electromagnetic properties have been achieved. With no degradation of the tensile strength or modulus, the shielding effectiveness of the structural composites has been improved by enhancing multiple reflections through light activation of the carbon fiber. The multiple reflections loss of the electromagnetic wave increases from 1.1 to 10.2 dB at 1.0 GHz due to the activation. Such a large effect of multiple reflections has not been previously reported in any material. The observability of these composites has been lowered by decreasing the electrical conductivity (and hence decreasing the reflection loss) through carbon fiber coating. The incorporation of mumetal, a magnetic alloy particulate filler (28-40 mum size), in a latex paint has been found to be effective for enhancing the shielding only if the electrical resistivity of the resulting composite coating is below 10 O.cm, as rendered by a conductive particulate filler, such as nickel flake (14-20 mum size). This effectiveness (39 dB at 1.0 GHz) is attributed to the absorption of the electromagnetic wave by the mumetal and the nickel flake, with the high conductivity rendered by the presence of the nickel flake resulting in a relatively high reflection loss of 15.5 dB. Without the nickel flake, the mumetal gives only 3 dB of shielding and 1.5 dB of reflection loss at 1.0 GHz. Nickel powder (0.3-0.5 mum size) has been found to be an effective filler for improving the shielding of polyethersulfone (PES

  2. THE GENERATION OF THERMOELASTIC STRESS WAVES BY IMPULSIVE ELECTROMAGNETIC RADIATION.

    Science.gov (United States)

    ELECTROMAGNETIC RADIATION , ABSORPTION), (*STRESSES, ELECTROMAGNETIC RADIATION ), SURFACE PROPERTIES, INTERACTIONS, HEAT TRANSFER, ELASTIC PROPERTIES, ELECTROMAGNETIC PULSES, LASERS, MATHEMATICAL ANALYSIS, BOUNDARY VALUE PROBLEMS, SOLIDS

  3. Explaining Electromagnetic Plane Waves in a Vacuum at the Introductory Level

    Science.gov (United States)

    Allred, Clark L.; Della-Rose, Devin J.; Flusche, Brian M.; Kiziah, Rex R.; Lee, David J.

    2010-01-01

    A typical introduction to electromagnetic waves in vacuum is illustrated by the following quote from an introductory physics text: "Maxwell's equations predict that an electromagnetic wave consists of oscillating electric and magnetic fields. The changing fields induce each other, which maintains the propagation of the wave; a changing electric…

  4. Massively sub-wavelength guiding of electromagnetic waves.

    Science.gov (United States)

    Hooper, I R; Tremain, B; Dockrey, J A; Hibbins, A P

    2014-12-16

    Recently a new form of ultra-thin flexible waveguide consisting of a conducting comb-like structure with a thickness of the order of 1/600(th) of the operating wavelength was presented. However, whilst the thickness of the guide was massively sub-wavelength, the remaining dimensions (the height and period of the comb) were much longer. In this paper we propose, and experimentally verify, that a modified guiding geometry consisting of a chain of ultra-thin conducting spirals allows guiding of electromagnetic waves with wavelengths that are many times (40+) longer than any characteristic dimension of the guide, enabling super-sub-wavelength guiding and localisation of electromagnetic energy.

  5. Role of surface electromagnetic waves in metamaterial absorbers.

    Science.gov (United States)

    Chen, Wen-Chen; Cardin, Andrew; Koirala, Machhindra; Liu, Xianliang; Tyler, Talmage; West, Kevin G; Bingham, Christopher M; Starr, Tatiana; Starr, Anthony F; Jokerst, Nan M; Padilla, Willie J

    2016-03-21

    Metamaterial absorbers have been demonstrated across much of the electromagnetic spectrum and exhibit both broad and narrow-band absorption for normally incident radiation. Absorption diminishes for increasing angles of incidence and transverse electric polarization falls off much more rapidly than transverse magnetic. We unambiguously demonstrate that broad-angle TM behavior cannot be associated with periodicity, but rather is due to coupling with a surface electromagnetic mode that is both supported by, and well described via the effective optical constants of the metamaterial where we achieve a resonant wavelength that is 19.1 times larger than the unit cell. Experimental results are supported by simulations and we highlight the potential to modify the angular response of absorbers by tailoring the surface wave.

  6. Total absorption of electromagnetic waves in ultimately thin layers

    CERN Document Server

    Ra'di, Younes; Tretyakov, Sergei A

    2012-01-01

    We consider single-layer arrays of electrically small lossy bi-anisotropic particles that completely absorb electromagnetic waves at normal incidence. Required conditions for electromagnetic properties of bi-anisotropic particles have been identified in the most general case of uniaxial reciprocal and nonreciprocal particles. We consider the design possibilities offered by the particles of all four fundamental classes of bianisotropic inclusions: reciprocal chiral and omega particles and nonreciprocal Tellegen and moving particles. We also study the reflection/transmission properties of asymmetric structures with different properties when illuminated from the opposite sides of the sheet. It has been found that it is possible to realize single-layer grids which exhibit the total absorption property when illuminated from one side but are totally transparent when illuminated from the other side (an ultimately thin isolator). Other possible properties are co-polarized or twist polarized reflection from the side o...

  7. Virtual Singular Scattering of Electromagnetic Waves in Transformation Media Concept

    Directory of Open Access Journals (Sweden)

    M. Y. Barabanenkov

    2012-07-01

    Full Text Available If a scatterer and an observation point (receive both approach the so-called near field zone of a source of electromagnetic waves, the scattering process becomes singular one which is mathematically attributed to the spatial singularity of the free space Green function at the origin. Starting from less well known property of left-handed material slab to transfer the singularity of the free space Green function by implementing coordinate transformation, we present a phenomenon of virtual singular scattering of electromagnetic wave on an inhomogeneity located in the volume of left – handed material slab. Virtual singular scattering means that a scatterer is situated only virtually in the near field zone of a source, being, in fact, positioned in the far field zone. Such a situation is realized if a scatterer is embedded into a flat Veselago’s lens and approaches the lens’s inner focus because a slab of Veselago medium produces virtual sources inside and behind the slab and virtual scatterer (as a source of secondary waves from both slab sides. Considering a line-like dielectric scatterer we demonstrate that the scattering efficiency is proportional to product of singular quasistatic parts of two empty space Green functions that means a multiplicative quasistatic singularity of the Green function for a slab of inhomogeneous Veselago medium. We calculate a resonance value of the scattering amplitude in the regime similar to the known Mie resonance scattering.

  8. Remarks on the Radiative Transfer Approach to Scattering of Electromagnetic Waves in Layered Random Media

    Science.gov (United States)

    2010-03-01

    AFRL-RY-HS-TR-2010-0029 REMARKS ON THE RADIATIVE TRANSFER APPROACH TO SCATTERING OF ELECTROMAGNETIC WAVES IN LAYERED RANDOM MEDIA...TRANSFER APPROACH TO SCATTERING OF ELECTROMAGNETIC WAVES IN LAYERED RANDOM MEDIA 5a. CONTRACT NUMBER IN-HOUSE 5b. GRANT NUMBER 5c. PROGRAM...Beckmann and A. Spizzichino. The Scattering of Electromagnetic Waves from Rough Surfaces. Artech House, Norwood, Massachusetts, 1987. [3] G. S. Brown. A

  9. SCATTERING OF ELECTROMAGNETIC WAVES FROM THE DISTURBANCE CAUSED BY A RAPIDLY MOVING BODY IN PLASMAS,

    Science.gov (United States)

    The scattering of electromagnetic waves by a body moving in a plasma is discussed in detail. General theory covering scattering phenomena is...conditions. The general theory is extended to investigate the following two problems: the scattering of electromagnetic waves from the disturbance caused...by a rapidly moving body in the ionosphere and the scattering of electromagnetic waves from the turbulent wake produuced by a re-entry vehicle. In

  10. Quantifying and predicting meat and meat products quality attributes using electromagnetic waves: an overview.

    Science.gov (United States)

    Damez, Jean-Louis; Clerjon, Sylvie

    2013-12-01

    The meat industry needs reliable meat quality information throughout the production process in order to guarantee high-quality meat products for consumers. Besides laboratory researches, food scientists often try to adapt their tools to industrial conditions and easy handling devices useable on-line and in slaughterhouses already exist. This paper overviews the recently developed approaches and latest research efforts related to assessing the quality of different meat products by electromagnetic waves and examines the potential for their deployment. The main meat quality traits that can be assessed using electromagnetic waves are sensory characteristics, chemical composition, physicochemical properties, health-protecting properties, nutritional characteristics and safety. A wide range of techniques, from low frequency, high frequency impedance measurement, microwaves, NMR, IR and UV light, to X-ray interaction, involves a wide range of physical interactions between the electromagnetic wave and the sample. Some of these techniques are now in a period of transition between experimental and applied utilization and several sensors and instruments are reviewed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Diffraction of Electromagnetic Waves on a Waveguide Joint

    Directory of Open Access Journals (Sweden)

    Malykh Mikhail

    2018-01-01

    Full Text Available In general, the investigation of the electromagnetic field in an inhomogeneous waveguide doesn’t reduce to the study of two independent boundary value problems for the Helmholtz equation. We show how to rewrite the Helmholtz equations in the “Hamiltonian form” to express the connection between these two problems explicitly. The problem of finding monochromatic waves in an arbitrary waveguide is reduced to an infinite system of ordinary differential equations in a properly constructed Hilbert space. The calculations are performed in the computer algebra system Sage.

  12. Broadband unidirectional behavior of electromagnetic waves based on transformation optics.

    Science.gov (United States)

    Zang, XiaoFei; Zhu, YiMing; Ji, XueBin; Chen, Lin; Hu, Qing; Zhuang, SongLin

    2017-01-20

    High directive antennas are fundamental elements for microwave communication and information processing. Here, inspired by the method of transformation optics, we propose and demonstrate a transformation medium to control the transmission path of a point source, resulting in the unidirectional behavior of electromagnetic waves (directional emitter) without any reflectors. The network of inductor-capacitor transmission lines is designed to experimentally realize the transformation medium. Furthermore, the designed device can work in a broadband frequency range. The unidirectional-manner-based device demonstrated in this work will be an important step forward in developing a new type of directive antennas.

  13. Spectrum of classes of point emitters of electromagnetic wave fields.

    Science.gov (United States)

    Castañeda, Román

    2016-09-01

    The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

  14. Motivating Non-science Majors: The Technology of Electromagnetic Waves

    Science.gov (United States)

    Henrich, Victor E.

    2018-01-01

    To address the need for physics courses that stimulate non-STEM majors' interest in, and appreciation of, science, the Department of Applied Physics has developed a popular course for Yale College undergraduates, The Technological World, that explains the physics behind technologies that students use every day. The course provides an in-depth development of electromagnetic waves, applying them to technologies as diverse as LCD displays, GPS, fiber optics, CAT scans, LEDs, and stealth aircraft. It utilizes a conventional lecture format, with many in-class demonstrations.

  15. Broadband unidirectional behavior of electromagnetic waves based on transformation optics

    Science.gov (United States)

    Zang, Xiaofei; Zhu, Yiming; Ji, Xuebin; Chen, Lin; Hu, Qing; Zhuang, Songlin

    2017-01-01

    High directive antennas are fundamental elements for microwave communication and information processing. Here, inspired by the method of transformation optics, we propose and demonstrate a transformation medium to control the transmission path of a point source, resulting in the unidirectional behavior of electromagnetic waves (directional emitter) without any reflectors. The network of inductor-capacitor transmission lines is designed to experimentally realize the transformation medium. Furthermore, the designed device can work in a broadband frequency range. The unidirectional-manner-based device demonstrated in this work will be an important step forward in developing a new type of directive antennas.

  16. Electromagnetic form factors of the Δ with D-waves

    Energy Technology Data Exchange (ETDEWEB)

    Ramalho, Gilberto T.F. [CFTP, Institute Superior Tecnico, Lisbon (Portugal); Pena, Maria Teresa [CFTP, Institute Superior Tecnico, Lisbon (Portugal); Gross, Franz L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2010-06-01

    The electromagnetic form factors of the Δ baryon are evaluated within the framework of a covariant spectator quark model, where S and D-states are included in the Δ wave function. We predict all the four Δ multipole form factors: the electric charge GE0, the magnetic dipole GM1, the electric quadrupole GE2 and the magnetic octupole GM3. We compare our predictions with other theoretical calculations. Our results are compatible with the available experimental data and recent lattice QCD data.

  17. Scattering of electromagnetic waves by a traversable wormhole

    Directory of Open Access Journals (Sweden)

    B. Nasr Esfahani

    2005-09-01

    Full Text Available   Replacing the wormhole geometry with an equivalent medium using the perturbation theory of scattering and the Born approximation, we have calculated the differential scattering cross section of electromagnetic waves by a traversable wormhole. It is shown that scattering at long wavelenghts can essentially distinguish wormhole from ordinary scattering object. Some of the zeros of the scattering cross section are determined which can be used for estimating the radius of the throat of wormholes. The known result that in this kind of scattering the linear polarization remains unchanged is verified here.

  18. Wave fields in real media wave propagation in anisotropic, anelastic, porous and electromagnetic media

    CERN Document Server

    Carcione, José M

    2014-01-01

    Authored by the internationally renowned José M. Carcione, Wave Fields in Real Media: Wave Propagation in Anisotropic, Anelastic, Porous and Electromagnetic Media examines the differences between an ideal and a real description of wave propagation, starting with the introduction of relevant stress-strain relations. The combination of this relation and the equations of momentum conservation lead to the equation of motion. The differential formulation is written in terms of memory variables, and Biot's theory is used to describe wave propagation in porous media. For each rheology, a plane-wave analysis is performed in order to understand the physics of wave propagation. This book contains a review of the main direct numerical methods for solving the equation of motion in the time and space domains. The emphasis is on geophysical applications for seismic exploration, but researchers in the fields of earthquake seismology, rock acoustics, and material science - including many branches of acoustics of fluids and ...

  19. Scattering of Electromagnetic Waves by Drift Vortex in Plasma

    Science.gov (United States)

    Wang, Dong; Chen, Yinhua; Wang, Ge

    2008-02-01

    In a quasi-two-dimensional model, the scattering of incident ordinary electromagnetic waves by a dipole-electrostatic drift vortex is studied with first-order Born approximation. The distribution of the scattering cross-section and total cross-section are evaluated analytically in different approximate conditions, and the physical interpretations are discussed. When the wavelength of incident wave is much longer than the vortex radius (kia ll 1), it is found that the angle at which the scattering cross-section reaches its maxim depends significantly on the approximation of the parameters of the vortex used. It is also found that the total scattering cross-section has an affinitive relation with the parameters of the plasma, while it is irrelevant to the frequency of the incident wave in a wide range of parameters of the vortex. In a totally different range of parameters when incident wave is in the radar-frequency range (then kia ll 1, the wavelength of incident wave is much shorter than the vortex radius), the numerical procedure is conducted with computer in order to obtain the distribution and the total expression of the scattering cross-section. Then it is found that the total scattering cross-section in the low frequency range is much larger than that in high frequency range, so the scattering is more effective in the low frequency range than in high frequency range.

  20. Nearly non-scattering electromagnetic wave set and its application

    Science.gov (United States)

    Liu, Hongyu; Wang, Yuliang; Zhong, Shuhui

    2017-04-01

    For any inhomogeneous compactly supported electromagnetic (EM) medium, it is shown that there exists an infinite set of linearly independent EM waves which generate nearly vanishing scattered wave fields. If the inhomogeneous medium is coated with a layer of properly chosen conducting medium, then the wave set is generated from the Maxwell-Herglotz approximation to the interior perfectly electric conducting or perfectly magnetic conducting eigenfunctions and depends only on the shape of the inhomogeneous medium. If no such a conducting coating is used, then the wave set is generated from the Maxwell-Herglotz approximation to the generalised interior transmission eigenfunctions and depends on both the content and shape of the inhomogeneous medium. We characterise the nearly non-scattering wave sets in both cases with sharp estimates. The results can be used to give a conceptual design of a novel shadowless lamp. The crucial ingredient is to properly choose the source of the lamp so that nearly no shadow will be produced by surgeons operating under the lamp.

  1. Electromagnetic induction and radiation-induced abnormality of wave propagation in excitable media

    Science.gov (United States)

    Ma, Jun; Wu, Fuqiang; Hayat, Tasawar; Zhou, Ping; Tang, Jun

    2017-11-01

    Continuous wave emitting from sinus node of the heart plays an important role in wave propagating among cardiac tissue, while the heart beating can be terminated when the target wave is broken into turbulent states by electromagnetic radiation. In this investigation, local periodical forcing is applied on the media to induce continuous target wave in the improved cardiac model, which the effect of electromagnetic induction is considered by using magnetic flux, then external electromagnetic radiation is imposed on the media. It is found that target wave propagation can be blocked to stand in a local area and the excitability of media is suppressed to approach quiescent but homogeneous state when electromagnetic radiation is imposed on the media. The sampled time series for membrane potentials decrease to quiescent state due to the electromagnetic radiation. It could accounts for the mechanism of abnormality in heart failure exposed to continuous electromagnetic field.

  2. Invisibility of a metamaterial cloak illuminated by spherical electromagnetic wave

    Science.gov (United States)

    Meng, Fan-Yi; Liang, Ying; Wu, Qun; Li, Le-Wei

    2009-06-01

    In this paper, the invisibility of a metamaterial cloak illuminated by spherical electromagnetic wave is analytically investigated based on the full wave Mie scattering model. It is shown that for a cloak with ideal parameters the scattered field intensity is zero, but for a cloak with a loss, only the backscattering is exactly zero. Moreover, in the loss case, the scattered field intensity increases as the loss increases, which is very different from that in the conventional stealth case, where the scattered field intensity decreases as the loss of coated material increases. In addition, it is shown that scattering cross-section of the cloak with perturbed parameters decreases as the thickness of the cloak decreases, which means that thinner cloak can exhibit more stable invisibility.

  3. Electromagnetic waves in complex systems selected theoretical and applied problems

    CERN Document Server

    Velychko, Lyudmyla

    2016-01-01

    This book gives guidance to solve problems in electromagnetics, providing both examples of solving serious research problems as well as the original results to encourage further investigations. The book contains seven chapters on various aspects of resonant wave scattering, each solving one original problem. All of them are unified by the authors’ desire to show advantages of rigorous approaches at all stages, from the formulation of a problem and the selection of a method to the interpretation of results. The book reveals a range of problems associated with wave propagation and scattering in natural and artificial environments or with the design of antennas elements. The authors invoke both theoretical (analytical and numerical) and experimental techniques for handling the problems. Attention is given to mathematical simulations, computational efficiency, and physical interpretation of the experimental results. The book is written for students, graduate students and young researchers. .

  4. A local-ether model of propagation of electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Su, C.C. [Dept. of Electrical Engineering, National Tsinghua University, Hsinchu (Taiwan)

    2001-07-01

    It is pointed out that the classical propagation model can be in accord with the Sagnac effect due to earth's rotational and orbital motions in the high-precision GPS (global positioning system) and interplanetary radar, if the reference frame of the classical propagation medium is endowed with a switchability according to the location of the wave. Accordingly, it is postulated that, as in the obsolete theory, electromagnetic waves propagate via a medium like the ether. However, the ether is not universal. It is proposed that in the region under sufficient influence of the gravity due to the earth, the sun, or another celestial body, there forms a local ether, which in turn is stationary with respect to the gravitational potential of the respective body. For earthbound and interplanetary propagation, the medium is stationary in a geocentric and a heliocentric inertial frame, respectively. An electromagnetic wave propagates at a constant speed with respect to the associated local ether, independent of the motions of source and receiver. Based on this local-ether model of wave propagation, a wide variety of earthbound, interplanetary, and interstellar propagation phenomena are accounted for. Strong evidence of this new classical model is its consistent account of the Sagnac effect due to earth's motions among GPS, the intercontinental microwave link, and the interplanetary radar. Moreover, as examined within the present precision, this model is still in accord with the Michelson-Morley experiment. To test the local-ether propagation model, a one-way-link rotor experiment is proposed. (orig.)

  5. Shaping electromagnetic waves using software-automatically-designed metasurfaces.

    Science.gov (United States)

    Zhang, Qian; Wan, Xiang; Liu, Shuo; Yuan Yin, Jia; Zhang, Lei; Jun Cui, Tie

    2017-06-15

    We present a fully digital procedure of designing reflective coding metasurfaces to shape reflected electromagnetic waves. The design procedure is completely automatic, controlled by a personal computer. In details, the macro coding units of metasurface are automatically divided into several types (e.g. two types for 1-bit coding, four types for 2-bit coding, etc.), and each type of the macro coding units is formed by discretely random arrangement of micro coding units. By combining an optimization algorithm and commercial electromagnetic software, the digital patterns of the macro coding units are optimized to possess constant phase difference for the reflected waves. The apertures of the designed reflective metasurfaces are formed by arranging the macro coding units with certain coding sequence. To experimentally verify the performance, a coding metasurface is fabricated by automatically designing two digital 1-bit unit cells, which are arranged in array to constitute a periodic coding metasurface to generate the required four-beam radiations with specific directions. Two complicated functional metasurfaces with circularly- and elliptically-shaped radiation beams are realized by automatically designing 4-bit macro coding units, showing excellent performance of the automatic designs by software. The proposed method provides a smart tool to realize various functional devices and systems automatically.

  6. Optical analysis of human eye using electromagnetic wave theory.

    Science.gov (United States)

    Can, Melih G; Oner, Bilgehan B; Kurt, Hamza

    2013-10-01

    We present a two-dimensional electromagnetic analysis of light propagation through the human eye to examine the eye's optical properties. The electromagnetic approach has intriguing advantages over the conventional and frequently implemented ray optics analysis. The chromatic, spherical, and coma aberrations and the intensity of the focused light at the retina are computed in this work via full-wave analysis. We also investigate the effects of the cornea's and lens's curved structures on the focusing mechanism. The focal length and chromatic and spherical aberrations are observed to change owing to age-related refractive index variation in the lens. In addition, the effects of the lens and curvatures of the human eye on focusing are analyzed. Consequently, for both young and old human eye lenses, the differences due to the aberration variations, curvature surfaces, and gradient index are explored by the wave approach. The intensity distributions on the retina for both on- and off-axis illumination are calculated. A strong correlation between the locations of the nerve fibers and the intensity distribution is confirmed. On the basis of the findings, we can conclude that visual impairment due to deterioration of the human eye structure is more dramatic than that due to aging.

  7. Excitation of planetary electromagnetic waves in the inhomogeneous ionosphere

    Directory of Open Access Journals (Sweden)

    Yu. Rapoport

    2014-04-01

    Full Text Available In this paper we develop a new method for the analysis of excitation and propagation of planetary electromagnetic waves (PEMW in the ionosphere of the Earth. The nonlinear system of equations for PEMW, valid for any height, from D to F regions, including intermediate altitudes between D and E and between E and F regions, is derived. In particular, we have found the system of nonlinear one-fluid MHD equations in the β-plane approximation valid for the ionospheric F region (Aburjania et al., 2003a, 2005. The series expansion in a "small" (relative to the local geomagnetic field non-stationary magnetic field has been applied only at the last step of the derivation of the equations. The small mechanical vertical displacement of the media is taken into account. We have shown that obtained equations can be reduced to the well-known system with Larichev–Reznik vortex solution in the equatorial region (see e.g. Aburjania et al., 2002. The excitation of planetary electromagnetic waves by different initial perturbations has been investigated numerically. Some means for the PEMW detection and data processing are discussed.

  8. Plug identification in drainage system using electromagnetic wave

    Science.gov (United States)

    Hijriani, Arifa; Utama, Aji Surya; Boas, Andrianus; Mukti, M. Ridho; Widodo

    2017-07-01

    The evaluation of drainage system's performance is an important thing to do to prevent flooding. Conventionally the Government evaluates the drainage system by opening one by one the lid of drainage and detects the plug manually. This method is not effective and efficient because this method need many people, much time and relatively expensive. The purpose of this paper is to identify plugs in drainage system in G St. at Bandung Institute of Technology by using electromagnetic wave. Ground Penetrating Radar (GPR) is one of geophysics method that using electromagnetic wave with high frequency. GPR is a non-destructive method with high resolution imaging for shallow depth (˜100m) and relatively cheap. We could identify the plug without opening the lid manually so that we could save much time. GPR's sensitivity is depends on resistivity, magnetic permeability, and permittivity of an object. The result of this research is we could identify the plug on the radargram that observed by a build-up amplitude anomaly.

  9. Carbon nanostructure composite for electromagnetic interference ...

    Indian Academy of Sciences (India)

    Blocking the electromagnetic radiation using barriers made up of conductive or mag- netic materials is called EMI shielding. The shielding material helps in absorbing or reflecting the EM radiation thereby acting as a shield by blocking the radiation from pen- etration into the shielded device. Earlier the most common way of ...

  10. Propagation of electromagnetic wave in dusty plasma and the influence of dust size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui [Department of Physics, Harbin Institute of Technology, Harbin (China); China Research Institute of Radio Wave Propagation (CRIRP), Beijing (China); Wu, Jian [China Research Institute of Radio Wave Propagation (CRIRP), Beijing (China); Zhou, Zhongxiang; Yuan, Chengxun [Department of Physics, Harbin Institute of Technology, Harbin (China)

    2016-07-15

    The effect of charged dust particle and their size distribution on the propagation of electromagnetic wave in a dusty plasma is investigated. It is shown that the additional collision mechanism provided by charged dust particles can significantly alter the electromagnetic properties of a plasma, leading to the appearance of attenuation of electromagnetic wave through dusty plasma. The attenuation coefficient mainly depends on the dust density, radius, and the charge numbers on the dust surface. The results described here will be used to enhance understanding of electromagnetic wave propagation processed in space and laboratory dusty plasma.

  11. Study on the characteristics of magneto-sensitive electromagnetic wave-absorbing properties of magnetorheological elastomers

    Science.gov (United States)

    Yu, Miao; Yang, Pingan; Fu, Jie; Liu, Shuzhi; Qi, Song

    2016-08-01

    Magnetorheological (MR) materials are a class of materials whose mechanical and electrical properties can be reversible controlled by the magnetic field. In this study, we pioneered research on the effect of a uniform magnetic field with different strengths and directions on the microwave-absorbing properties of magnetorheological elastomers (MREs), in which the ferromagnetic particles are flower-like carbonyl iron powders (CIPs) prepared by an in situ reduction method. The electromagnetic (EM) absorbing properties of the composites have been analyzed by vector network analysis with the coaxial reflection/transmission technique. Under the magnetic field, the columnar or chainlike structures were formed, which allows EM waves to penetrate. Meanwhile, stronger Debye dipolar relaxation and attenuation constant have been obtained when changing the direction of the applied magnetic field. Compared with untreated MREs, not only have the minimum reflection loss (RL) and the effective absorption bandwidth (below -20 dB) greatly increased, the frequencies of the absorbing peaks shift about 15%. This suggests that MREs are a magnetic-field-sensitive electromagnetic wave-absorbing material and have great potential in applications such as in anti-radar camouflage, due to the fact that radar can continuously conduct detection at many electromagnetic frequencies, while the MR materials can adjust the microwave-absorption peak according to the radar frequency.

  12. Second-Harmonic Generation by Electromagnetic Waves at the Surface of a Semi-Infinite Metal

    Science.gov (United States)

    2010-05-01

    Second-Harmonic Generation by Electromagnetic Waves at the Surface of a Semi-Infinite Metal Frank Crowne and Christian Fazi Sensors and...DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Second-Harmonic Generation by Electromagnetic Waves at the Surface of a Semi

  13. Examination of Bursty Electromagnetic Waves Observed During Intervals of Turbulent Magnetosheath Reconnection

    Science.gov (United States)

    Adrian, Mark L.; Wendel, D. E.

    2011-01-01

    We investigate observations of intense bursts of electromagnetic waves in association with magnetic reconnection in the turbulent magnetosheath. These structured, broadband bursts occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed at local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic waves and quantify their proximity to X- and O-nulls.

  14. Rotatable illusion media for manipulating terahertz electromagnetic waves.

    Science.gov (United States)

    Zang, XiaoFei; Li, Zhou; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing; Li, Li; Wang, XiaoBin

    2013-10-21

    Based on composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter-independent cloaks when the incident wave with a certain width propagates from specific incident directions. The fundamental mechanism of this kind of cloak is that the illusion media can be able to avoid the incident wave interacting with the objects. Comparing with traditional transformation-coordinate-based cloaks such as cylindrical-shaped cloaks, our cloaks are independent of singular material parameters. Furthermore, this type of rotatable illusion media can be applied to design tunable miniaturized high-directivity antenna (a small antenna array covered with the rotatable illusion media appears like a large one and meanwhile, the radiation directions of the small antenna array is tunable via this rotatable illusion media). Full wave simulations are performed to confirm these points.

  15. Propagation of electromagnetic waves in Bose-Einstein condensate of atoms with dipole moments

    OpenAIRE

    Poluektov, Yu. M.; Tanatarov, I. V.

    2014-01-01

    We study the propagation of electromagnetic waves in the Bose-Einstein condensate of atoms with both intrinsic dipole moments and those induced by the electric field. The modified Gross--Pitaevskii equation is used, which takes into account relaxation and interaction with the electromagnetic field. Two cases are considered: 1) when the dispersion curves of the electromagnetic wave and of the condensate excitations do not intercross and 2) when the condensate excitations' spectrum has a gap an...

  16. Electromagnetic Components of Auroral Hiss and Lower Hybrid Waves in the Polar Magnetosphere

    Science.gov (United States)

    Wong, H. K.

    1995-01-01

    DE-1 has frequently observed waves in the whistler and lower hybrid frequencies range. Besides the electrostatic components, these waves also exhibit electromagnetic components. It is generally believed that these waves are excited by the electron acoustic instability and the electron-beam-driven lower hybrid instability. Because the electron acoustic and the lower hybrid waves are predominately electrostatic waves, they cannot account for the observed electromagnetic components. In this work, it is suggested that these electromagnetic components can be explained by waves that are generated near the resonance cone and that propagate away from the source. The role that these electromagnetic waves can play in particle acceleration processes at low altitude is discussed.

  17. The Characteristics of Frequency Spectrum of Radiated Electromagnetic Waves with AC Discharge Progress in Liquid Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Park, K.S.; Yoon, D.H.; Lee, S.H.; Kim, K.C.; Lee, K.S. [Yeungnam University, Gyeongsan (Korea); Lee, H.D. [LG Industrial Systems Co., Ltd., Cheongju (Korea); Kim, C.M. [Kyungwoon University, Kumi (Korea); Choi, B.J. [Sorabol College, Gyeongju (Korea)

    2003-03-01

    In this paper, a relationship between AC discharge progress and the radiated electromagnetic waves was investigated by measuring electromagnetic waves using a biconical antenna and a spectrum analyzer. The frequency spectrum of the radiated electromagnetic waves were measured at the atmospheric pressure in liquid nitrogen(LN{sub 2}) during partial discharges progressed by AC high voltage in nonuniform electric field. From the results of this study, a new method was introduced for measurement and analysis of the radiated electromagnetic waves with discharge progress in LN{sub 2}. Besides, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting partial discharge and estimating discharge progress could be possible. It is considered that these results obtained from this investigation may be used as fundamental data for diagnosis and prediction of electric insulations about superconducting and cryogenic power equipments. (author). 14 refs., 7 figs.

  18. Electromagnetic waves near the proton cyclotron frequency: Stereo observations

    Energy Technology Data Exchange (ETDEWEB)

    Jian, L. K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Wei, H. Y.; Russell, C. T. [Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095 (United States); Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA 94720 (United States); Klecker, B. [Max-Planck-Institut für Extraterrestrische Physik, D-85741 Garching (Germany); Omidi, N. [Solana Scientific Inc., Solana Beach, CA 92075 (United States); Isenberg, P. A. [Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 (United States); Goldstein, M. L.; Figueroa-Viñas, A. [Heliophysics Science Division, NASA Goddard Space Flight Center, MD 20771 (United States); Blanco-Cano, X., E-mail: lan.jian@nasa.gov [Instituto de Geofisica, Universidad Nacional Autónoma de México, Coyoacán D.F. (Mexico)

    2014-05-10

    Transverse, near-circularly polarized, parallel-propagating electromagnetic waves around the proton cyclotron frequency were found sporadically in the solar wind throughout the inner heliosphere. They could play an important role in heating and accelerating the solar wind. These low-frequency waves (LFWs) are intermittent but often occur in prolonged bursts lasting over 10 minutes, named 'LFW storms'. Through a comprehensive survey of them from Solar Terrestrial Relations Observatory A using dynamic spectral wave analysis, we have identified 241 LFW storms in 2008, present 0.9% of the time. They are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame with similar characteristics, probably due to Doppler shift of the same type of waves or waves of intrinsically different polarities. In rare cases, the opposite polarities are observed closely in time or even simultaneously. Having ruled out interplanetary coronal mass ejections, shocks, energetic particles, comets, planets, and interstellar ions as LFW sources, we discuss the remaining generation scenarios: LH ion cyclotron instability driven by greater perpendicular temperature than parallel temperature or by ring-beam distribution, and RH ion fire hose instability driven by inverse temperature anisotropy or by cool ion beams. The investigation of solar wind conditions is compromised by the bias of the one-dimensional Maxwellian fit used for plasma data calibration. However, the LFW storms are preferentially detected in rarefaction regions following fast winds and when the magnetic field is radial. This preference may be related to the ion cyclotron anisotropy instability in fast wind and the minimum in damping along the radial field.

  19. EMC characteristics of composite structure - Electric/electromagnetic shielding attenuation

    Science.gov (United States)

    Wegertseder, P.; Breitsameter, R.

    1989-09-01

    The paper reports electric/electromagnetic shielding-attenuation experiments performed on different test boxes built with the same materials and processes as those to be used for the construction of a helicopter. The measurements are performed in the frequency range of 14 to 18 GHz, and the effects of different composite materials, jointing and bonding of structure parts of the boxes, application and bonding of the mesh, the construction of access panels, and conductive seals on these panels are assessed. It is demonstrated that moderate electric/electromagnetic shielding-attenuation values can be achieved by composite structures made from carbon, and materials and procedures required for high shielding attenuation are discussed.

  20. Semiannual Status Report. [excitation of electromagnetic waves in the whistler frequency range

    Science.gov (United States)

    1994-01-01

    During the last six months, we have continued our study of the excitation of electromagnetic waves in the whistler frequency range and the role that these waves will play in the acceleration of electrons and ions in the auroral region. A paper entitled 'Electron Beam Excitation of Upstream Waves in the Whistler Mode Frequency Range' was listed in the Journal of Geophysical Research. In this paper, we have shown that an anisotropic electron beam (or gyrating electron beam) is capable of generating both left-hand and right-hand polarized electromagnetic waves in the whistler frequency range. Since right-hand polarized electromagnetic waves can interact with background electrons and left-hand polarized waves can interact with background ions through cyclotron resonance, it is possible that these beam generated left-hand and right-hand polarized electromagnetic waves can accelerate either ions or electrons (or both), depending on the physical parameters under consideration. We are currently carrying out a comprehensive study of the electromagnetic whistler and lower hybrid like waves observed in the auroral zone using both wave and particle data. Our first task is to identify these wave modes and compare it with particle observations. Using both the DE-1 particle and wave measurements, we can positively identify those electromagnetics lower hybrid like waves as fast magnetosonic waves and the upper cutoff of these waves is the local lower hybrid frequency. From the upper cutoff of the frequency spectrum, one can infer the particle density and the result is in very good agreement with the particle data. Since these electromagnetic lower hybrid like waves can have frequencies extended down to the local ion cyclotron frequency, it practically confirms that they are not whistler waves.

  1. Scattering of an electromagnetic plane wave by a Luneburg lens. II. Wave theory.

    Science.gov (United States)

    Lock, James A

    2008-12-01

    The partial wave scattering and interior amplitudes for the interaction of an electromagnetic plane wave with a modified Luneburg lens are derived in terms of the exterior and interior radial functions of the scalar radiation potentials evaluated at the lens surface. A Debye series decomposition of these amplitudes is also performed and discussed. The effective potential inside the lens for the transverse electric polarization is qualitatively examined, and the approximate lens size parameters of morphology-dependent resonances are determined. Finally, the physical optics model is used to calculate wave scattering in the vicinity of the ray theory orbiting condition in order to demonstrate the smoothing of ray theory discontinuities by the diffraction of scattered waves.

  2. An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials

    Directory of Open Access Journals (Sweden)

    Adriana Savin

    2015-07-01

    Full Text Available This paper proposes the study and implementation of a sensor with a metamaterial (MM lens in electromagnetic nondestructive evaluation (eNDE. Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000.

  3. Finite Element Modeling of scattered electromagnetic waves for stroke analysis.

    Science.gov (United States)

    Priyadarshini, N; Rajkumar, E R

    2013-01-01

    Stroke has become one of the leading causes of mortality worldwide and about 800 in every 100,000 people suffer from stroke each year. The occurrence of stroke is ranked third among the causes of acute death and first among the causes for neurological dysfunction. Currently, Neurological examinations followed by medical imaging with CT, MRI or Angiography are used to provide better identification of the location and the type of the stroke, however they are neither fast, cost-effective nor portable. Microwave technology has emerged to complement these modalities to diagnose stroke as it is sensitive to the differences between the distinct dielectric properties of the brain tissues and blood. This paper investigates the possibility of diagnosing the type of stroke using Finite Element Analysis (FEA). The object of interest is a simulated head phantom with stroke, created with its specifying material characteristics like electrical conductivity and relative permittivity. The phantom is then placed in an electromagnetic field generated by a dipole antenna radiating at 1 GHz. The FEM forward model solver computes the scattered electromagnetic field by finding the solution for the Maxwell's wave equation in the head volume. Subsequently the inverse scattering problem is solved using the Contrast Source Inversion (CSI) method to reconstruct the dielectric profile of the head phantom.

  4. Scattering of electromagnetic plane waves by a buried vertical dike

    Directory of Open Access Journals (Sweden)

    Batista Lurimar S.

    2003-01-01

    Full Text Available The complete and exact solution of the scattering of a TE mode frequency domain electromagnetic plane wave by a vertical dike under a conductive overburden has been established. An integral representation composed of one-sided Fourier transforms describes the scattered electric field components in each one of the five media: air, overburden, dike, and the country rocks on both sides of the dike. The determination of the terms of the series that represents the spectral components of the Fourier integrals requires the numerical inversion of a sparse matrix, and the method of successive approaches. The zero-order term of the series representation for the spectral components of the overburden, for given values of the electrical and geometrical parameters of the model, has been computed. This result allowed to determine an approximate value of the variation of the electric field on the top of the overburden in the direction perpendicular to the strike of the dike. The results demonstrate the efficiency of this forward electromagnetic modeling, and are fundamental for the interpretation of VLF and Magnetotelluric data.

  5. Electromagnetic wave propagation through a slab of a dispersive medium

    CERN Document Server

    Ismail, Mohamed

    2016-01-01

    A method is proposed for the analysis of the propagation of electromagnetic waves through a homogeneous slab of a medium with Drude-Lorentz dispersion behavior, and excited by a causal sinusoidal source. An expression of the time dependent field, free from branch-cuts in the plane of complex frequencies, is established. This method provides the complete temporal response in both the steady-state and transient regimes in terms of discrete poles contributions. The Sommerfeld and Brillouin precursors are retrieved and the corresponding set of poles are identified. In addition, the contribution in the transient field of the resonance frequency in the Drude-Lorentz model is exhybited, and the effect of reflections resulting from the refractive index mismatch at the interfaces of the slab are analyzed.

  6. Diffraction of Electromagnetic Wave by Circular Disk and Circular Hole

    CERN Document Server

    Shahzad, Muhammad Adnan

    2010-01-01

    The problem of diffraction of an electromagnetic plane wave by a perfectly conducting circular disk and its complementary problem, diffraction by a circular hole in an infinite conducting plate, are rigorously solved using the method of the Kobayashi potential. The mathematical formulation involved dual integral equation derived from the potential integral and boundary condition on the plane where a disk or hole is located. The weighting function in the potential integral are determined by applying the properties of the Weber-Schafheitlin's discontinuous integral and the solution are obtained in the form of a matrix equation. The matrix elements of the equations for the expansion coefficients are given by three kinds of infinite integral and the series solution for these infinite integral are derived. For the verification of these series solution, the numerical integral are derived and the results are computed numerically using the method of Gaussian quadrature for conformation. The numerical results are give...

  7. Electromagnetic waves propagation through a stochastic anisotropic medium

    Energy Technology Data Exchange (ETDEWEB)

    Ledinegg, E.

    1985-01-01

    Electromagnetic waves propagating through a stochastic medium are disturbed by field fluctuations. These can be treated by use of multiple scattering theories in order to get realistic results. In this paper, the multiple scattering theory developed by B.J. Uscinski is employed for anisotropic media and first and second-order field moments are calculated. Extending an earlier paper, the author considers primary fields with an arbitrary angle of incidence in order to investigate problems of practical interest (i.e.: radio propagation through the ionosphere between satellite and ground stations). As a result, it is shown that the attenuation factor of the first order field moment depends strongly on the angle of incidence due to media fluctuations.

  8. Carbon Hollow Microspheres with a Designable Mesoporous Shell for High-Performance Electromagnetic Wave Absorption.

    Science.gov (United States)

    Xu, Hailong; Yin, Xiaowei; Zhu, Meng; Han, Meikang; Hou, Zexin; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2017-02-22

    In this work, mesoporous carbon hollow microspheres (PCHMs) with designable mesoporous shell and interior void are constructed by a facile in situ stöber templating approach and a pyrolysis-etching process. The PCHMs are characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and nitrogen adsorption and desorption system. A uniform mesoporous shell (pore size 4.7 nm) with a thickness of 55 nm and a cavity size of 345 nm is realized. The composite of paraffin mixed with 20 wt % PCHMs exhibits a minimum reflection coefficient (RCmin) of -84 dB at 8.2 GHz with a sample thickness of 3.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz below -10 dB (>90% electromagnetic wave is attenuated). Moreover, the composite of phenolic resin mixed with 20 wt % PCHMs exhibits an ultrawide EAB of 8 GHz below -10 dB with a thinner thickness of 2.15 mm. Such excellent electromagnetic wave absorption properties are ascribed to the large carbon-air interface in the mesoporous shell and interior void, which is favorable for the matching of characteristic impedance as compared with carbon hollow microspheres and carbon solid microspheres. Considering the excellent performance of PCHMs, we believe the as-fabricated PCHMs can be promising candidates as highly effective microwave absorbers, and the design philosophy can be extended to other spherical absorbers.

  9. Electromagnetic wave control of ceramic/resin photonic crystals with diamond structure

    Directory of Open Access Journals (Sweden)

    Soshu Kirihara, Mitsuo Takeda, Kazuaki Sakoda and Yoshinari Miyamoto

    2004-01-01

    Full Text Available Millimeter-order photonic crystals with the periodic arrangement of the dielectric constant were fabricated by infiltrating the mixed slurry of ceramics and polyester into the epoxy molds with an inverse form of a diamond structure. The epoxy molds are designed and processed by using a CAD/CAM process of stereolithography. The photonic crystals were prepared to have the diamond structure of the ceramic/polyester composite lattice, which is embedded in the epoxy matrix. The ceramic powders mixed with polyester are TiO2, SrTiO3, and BaTiO3 with high dielectric constant. It is possible to control more freely and widely the dielectric constant of the photonic crystals by this method. These ceramic/resin photonic crystals formed the complete photonic band gaps in the microwave band of 7–11 GHz, which can totally reflect the electromagnetic wave for all crystal directions. Attenuation profiles of the transmission amplitude in the band gaps were controlled with the dielectric constant of the composite lattice. The obtained results fairly agreed with the theoretical simulation of the electromagnetic wave propagation through photonic crystals.

  10. Electromagnetic Waves and Bursty Electron Acceleration: Implications from Freja

    Science.gov (United States)

    Andersson, Laila; Ivchenko, N.; Wahlund, J.-E.; Clemmons, J.; Gustavsson, B.; Eliasson, L.

    2000-01-01

    Dispersive Alfven wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about I keV, transverse ion heating and broadband extremely low frequency (ELF) emissions below the lower hybrid cutoff frequency (a few kHz). The broadband emissions are observed to become more electrostatic towards higher frequencies. Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E- and B-field fluctuations below 64 Hz (the dc instrument's upper threshold) and the characteristics of the precipitating electrons. This study revealed that the energization of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvenic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfven waves set up these local field-aligned current regions and in turn trigger more electrostatic emissions during certain conditions. In these regions ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods.

  11. Cellular and molecular effects of electromagnetic radiation and sonic waves

    Directory of Open Access Journals (Sweden)

    Patricia Froes Meyer

    2013-07-01

    Full Text Available Electromagnetic radiation (in the form of pulsed magnetic fields, radiofrequency and intense pulsed light and mechanical agents (such as sonic waves have been used in physical therapy. The aim of this study was to assess the effects of low-intensity magnetic fields, sonic and radiofrequency waves, and intense pulsed light on the survival of Escherichia coli cultures and on the electrophoretic mobility of plasmid DNA. Exponentially growing E. coli AB1157 cultures and plasmid DNA samples were exposed to these physical agents and 0.9% NaCl (negative control and SnCl2 (positive control solutions. Aliquots of the cultures were diluted and spread onto a solidified rich medium. The colony-forming units were counted after overnight incubation and the survival fraction was calculated. Agarose gel electrophoresis was performed to visualise and quantify the plasmid topological forms. The results suggest that these agents do not alter the survival of E. coli cells or plasmid DNA electrophoresis mobility. Moreover, they do not protect against the lesive action of SnCl2. These physical agents therefore had no cytotoxic or genotoxic effects under the conditions studied.

  12. Risk perception and public concerns of electromagnetic waves from cellular phones in Korea.

    Science.gov (United States)

    Kim, Kyunghee; Kim, Hae-Joon; Song, Dae Jong; Cho, Yong Min; Choi, Jae Wook

    2014-05-01

    In this study, the difference between the risk perception of electromagnetic waves from cellular phones and the risk perception of other factors such as environment and food was analyzed. The cause of the difference in the psychological and social factors that affect the group with high risk perception of electromagnetic waves was also analyzed. A questionnaire survey on the risk perception of electromagnetic waves from cellular phones was carried out on 1001 subjects (men and women) over the age of 20. In the group with high risk perception of electromagnetic waves from cellular phones, women had higher risk perception than men. Logistic regression analysis, where the group with high risk perception of electromagnetic waves and the group with low risk perception were used as dependent variables, indicated that the risk perception of electromagnetic waves in women was 1.815 times statistically significantly higher than the risk perception of men (95% CI: 1.340-2.457). Also, high risk perception of electromagnetic waves from cellular phones was observed when the subjects considered that they had more personal knowledge (OR: 1.416, 95% CI: 1.216-1.648), that the seriousness of the risk to future generations was high (OR: 1.410, 95% CI: 1.234-1.611), and their outrage for the occurrence of accidents related to electromagnetic waves was high (OR: 1.460, 95% CI: 1.264-1.686). The results of this study need to be sufficiently considered and reflected in designing the risk communication strategies and communication methods for the preventive measures and advice on electromagnetic waves from cellular phones. © 2014 Wiley Periodicals, Inc.

  13. Electromagnetic waves and bursty electron acceleration: implications from Freja

    Directory of Open Access Journals (Sweden)

    L. Andersson

    Full Text Available Dispersive Alfvén wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about 1 keV, transverse ion heating and broadband extremely low frequency (ELF emissions below the lower hybrid cutoff frequency (a few kHz. Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E and B field fluctuations below 64 Hz and 10 Hz, respectively, (the DC instruments upper threshold and the characteristics of the precipitating electrons. This study revealed that the energisation of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvénic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfvén waves set up these local field-aligned current regions and, in turn, trigger more electrostatic emissions during certain conditions. In these regions, ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods.

    Key words. Ionosphere (particle acceleraton; wave-particle interactions Magnetospheric physics (auroral phenomena

  14. Metamaterials, from electromagnetic waves to water waves, bending waves and beyond

    KAUST Repository

    Dupont, G.

    2015-08-04

    We will review our recent work on metamaterials for different types of waves. Transposition of transform optics to water waves and bending waves on plates will be considered with potential applications of cloaking to water waves protection and anti-vibrating systems.

  15. Equivalent Electromagnetic Constants for Microwave Application to Composite Materials for the Multi-Scale Problem

    Science.gov (United States)

    Fujisaki, Keisuke; Ikeda, Tomoyuki

    2013-01-01

    To connect different scale models in the multi-scale problem of microwave use, equivalent material constants were researched numerically by a three-dimensional electromagnetic field, taking into account eddy current and displacement current. A volume averaged method and a standing wave method were used to introduce the equivalent material constants; water particles and aluminum particles are used as composite materials. Consumed electrical power is used for the evaluation. Water particles have the same equivalent material constants for both methods; the same electrical power is obtained for both the precise model (micro-model) and the homogeneous model (macro-model). However, aluminum particles have dissimilar equivalent material constants for both methods; different electric power is obtained for both models. The varying electromagnetic phenomena are derived from the expression of eddy current. For small electrical conductivity such as water, the macro-current which flows in the macro-model and the micro-current which flows in the micro-model express the same electromagnetic phenomena. However, for large electrical conductivity such as aluminum, the macro-current and micro-current express different electromagnetic phenomena. The eddy current which is observed in the micro-model is not expressed by the macro-model. Therefore, the equivalent material constant derived from the volume averaged method and the standing wave method is applicable to water with a small electrical conductivity, although not applicable to aluminum with a large electrical conductivity. PMID:28788395

  16. Ion acoustic wave generation by a standing electromagnetic field in a subcritical plasma

    OpenAIRE

    P. Fischer; Gauthereau, C.; Godiot, J.; G. Matthieussent

    1987-01-01

    An electromagnetic wave ( f = 9 GHz, Pi = 150 kW, τ = 1.5 μs) is launched into a subcritical argon plasma (n e ≃1011 cm-3, P0 ≃ 5 × 10-4 Torr), resulting in a standing wave. The associated ponderomotive force generates an ion acoustic wave with a wave vector equal to twice the electromagnetic one and with a frequency satisfying the usual dispersion relation (fA ≃ 150 kHz). The main features of the ion acoustic wave, as measured in this 3D experiment, agree with a simple theory. However, varyi...

  17. Thin Perfect Absorbers for Electromagnetic Waves: Theory, Design, and Realizations

    Science.gov (United States)

    Ra'di, Y.; Simovski, C. R.; Tretyakov, S. A.

    2015-03-01

    With recent advances in nanophotonics and nanofabrication, considerable progress has been achieved in realizations of thin composite layers designed for full absorption of incident electromagnetic radiation, from microwaves to the visible. If the layer is structured at a subwavelength scale, thin perfect absorbers are usually called "metamaterial absorbers," because these composite structures are designed to emulate some material responses not reachable with any natural material. On the other hand, many thin absorbing composite layers were designed and used already in the time of the introduction of radar technology, predominantly as a means to reduce radar visibility of targets. In view of a wide variety of classical and new topologies of optically thin metamaterial absorbers and plurality of applications, there is a need for a general, conceptual overview of the fundamental mechanisms of full absorption of light or microwave radiation in thin layers. Here, we present such an overview in the form of a general theory of thin perfectly absorbing layers. Possible topologies of perfect metamaterial absorbers are classified based on their fundamental operational principles. For each of the identified classes, we provide design equations and give examples of particular realizations. The concluding section provides a summary and gives an outlook on future developments in this field.

  18. What is the impact of electromagnetic waves on epileptic seizures?

    Science.gov (United States)

    Cinar, Nilgun; Sahin, Sevki; Erdinc, Oguz O

    2013-05-10

    The effects of electromagnetic waves (EMWs) on humans and their relationship with various disorders have been investigated. We aimed to investigate the effects of exposure to different frequencies of EMWs in various durations in a mouse epilepsy model induced by pentylenetetrazole (PTZ). A total of 180 4-week-old male mice weighing 25-30 g were used in this study. Each experimental group consisted of 10 mice. They were exposed to 900, 700, 500, 300, and 100 MHz EMWs for 20 hours, 12 hours and 2 hours. Following electromagnetic radiation exposure, 60 mg/kg of PTZ was injected intraperitoneally to all mice. Each control was also injected with PTZ without any exposure to EMW. The latency of initial seizure and most severe seizure onset were compared with controls. The shortest initial seizure latency was noted in the 12-hour group, followed by the 700 MHz. The mean initial seizure latencies in the 2-hour EMW exposed group was significantly shorter compared to that in the 12- and 20-hour groups. There was no significant difference between 12- and 20-hour EMW exposed groups. There was a significant difference between control and 2- and 10-hour EMW exposed groups. No statistically significant differences were noted in mean latencies of the most severe seizure latency, following 20-, 12-, and 2- hour EMW exposed groups and control groups. Our findings suggest that acute exposure to EMW may facilitate epileptic seizures, which may be independent of EMW exposure time. This information might be important for patients with epilepsy. Further studies are needed.

  19. The modulation of electromagnetic ion cyclotron waves by Pc 5 ULF waves

    Directory of Open Access Journals (Sweden)

    T. M. Loto'aniu

    2009-01-01

    Full Text Available The modulation of electromagnetic ion cyclotron (EMIC waves by longer-period ULF waves has been proposed as a method for producing pearl structured Pc 1–2 EMIC waves. This study examines frequency and phase relationship between Pc 1 EMIC wavepacket envelopes and simultaneously occurring Pc 5 ULF waves using magnetic data measured by the CRRES spacecraft. Intervals from three days in 1991 where CRRES observed pearls are presented along with simple statistics for 58 EMIC wavepackets. The observations were dominated by EMIC waves propagating away from the equatorial region. Comparisons between pearl wavepacket envelopes and Pc 5 waves show excellent agreement. The pearl wavepacket duration times, τdur, were statistically correlated with Pc 5 wave periods, TPc5, resulting in a correlation coefficient of R=0.7 and best fit equation τdur=0.8·TPc5+6 s. In general, phase differences varied although time intervals of constant in-phase or anti-phase correlation were observed. Anti-phase modulation may be explained by a decreasing background magnetic field due to the negative cycle of the ULF wave decreasing Alfvén velocity and minimum resonant energy. In-phase modulation could be the result of adiabatic modulation of temperature anisotropy in-phase with variations in the background field. Non-adiabatic processes may contribute to intervals that showed varying phase differences with time. Results suggest that future theoretical developments should take into account the full range of possible wave particle interactions inside the magnetosphere.

  20. Leaky surface electromagnetic waves on a high-index dielectric grating.

    Science.gov (United States)

    Maradudin, A A; Simonsen, I; Zierau, W

    2016-05-15

    We show theoretically that the periodically corrugated surface of a high-index dielectric medium can support a leaky surface electromagnetic wave. This wave is bound to the surface in the vacuum, but radiates into the dielectric. Despite this radiative damping, the surface wave can have a long lifetime.

  1. Damping and scattering of electromagnetic waves by small ferrite spheres suspended in an insulator

    Science.gov (United States)

    Englert, Gerald W.

    1992-01-01

    The intentional degradation of electromagnetic waves by their penetration into a media comprised of somewhat sparsely distributed energy absorbing ferrite spheres suspended in an electrical insulator is investigated. Results are presented in terms of generalized parameters involving wave length and sphere size, sphere resistivity, permeability, and spacing; their influence on dissipation of wave power by eddy currents, magnetic hysteresis, and scattering is shown.

  2. Excitation of surface electromagnetic waves in a graphene-based Bragg grating.

    Science.gov (United States)

    Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

    2012-01-01

    Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc.

  3. A theory of electrical conductivity, dielectric constant, and electromagnetic interference shielding for lightweight graphene composite foams

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Xiaodong [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China); Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, New Jersey 08903 (United States); Wang, Yang; Weng, George J., E-mail: weng@jove.rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, New Jersey 08903 (United States); Zhong, Zheng [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China)

    2016-08-28

    This work was driven by the need to understand the electromagnetic interference (EMI) shielding effectiveness (SE) of light weight, flexible, and high performance graphene composite foams, but as EMI SE of a material depends on its electrical conductivity, dielectric permittivity, and magnetic permeability, the investigation of these three properties also became a priority. In this paper, we first present a continuum theory to determine these three electromagnetic properties, and then use the obtained properties to evaluate the EMI SE of the foam. A two-scale composite model is conceived to evaluate these three properties, with the large one being the skeleton-void composite and the small one being the graphene-polymer composite that serves as the skeleton of the foam. To evaluate the properties of the skeleton, the effective-medium approach is taken as the starting point. Subsequently, the effect of an imperfect interface and the contributions of electron tunneling to the interfacial conductivity and Maxwell-Wagner-Sillars polarization mechanism to the dielectric constant are also implemented. The derived skeleton properties are then utilized on the large scale to determine the three properties of the composite foam at a given porosity. Then a uniform plane electromagnetic wave is considered to evaluate the EMI SE of the foam. It is demonstrated that the electrical conductivity, dielectric constant, and EMI SE of the foam calculated from the developed theory are in general agreement with the reported experimental data of graphene/PDMS composite foams. The theory is further proven to be valid for the EMI SE of solid graphene/epoxy and solid carbon nanotube/epoxy nanocomposites. It is also shown that, among the three electromagnetic properties, electrical conductivity has the strongest influence on the EMI shielding effectiveness.

  4. Diodelike asymmetric transmission of linearly polarized waves using magnetoelectric coupling and electromagnetic wave tunneling.

    Science.gov (United States)

    Mutlu, Mehmet; Akosman, Ahmet E; Serebryannikov, Andriy E; Ozbay, Ekmel

    2012-05-25

    An asymmetric, reciprocal, diffraction-free transmission of linearly polarized waves in a new diodelike, three-layer, ultrathin, chiral structure is studied theoretically and experimentally. The exploited physical mechanism is based on the maximization of the cross-polarized transmission in one direction due to the polarization selectivity dictated by the peculiar eigenstate combination, which is efficiently controlled by the electromagnetic tunneling through the metallic subwavelength mesh sandwiched between these layers. Simulation and microwave experiment results demonstrate a nearly total intensity transmission at normal incidence in one direction and a small intensity transmission in the opposite direction.

  5. Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Pyoung-Chan, E-mail: pclee@katech.re.kr; Kim, Bo-Ram; Jeoung, Sun Kyoung [Korea Automotive Technology lnstitute, Dongnam-Gu, Chonan-Si, Chungnam 330-912 (Korea, Republic of); Kim, Yeung Keun [Win& Win Co., Ltd., Anseong-Si, Gyeonggi-Do, 456-931 (Korea, Republic of)

    2016-03-09

    Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

  6. Vector-based plane-wave spectrum method for the propagation of cylindrical electromagnetic fields.

    Science.gov (United States)

    Shi, S; Prather, D W

    1999-11-01

    We present a vector-based plane-wave spectrum (VPWS) method for efficient propagation of cylindrical electromagnetic fields. In comparison with electromagnetic propagation integrals, the VPWS method significantly reduces time of propagation. Numerical results that illustrate the utility of this method are presented.

  7. Coupled poroelastic waves and electromagnetic fields in layered media : Theory, Modeling, and Interferometric Synthesis

    NARCIS (Netherlands)

    Grobbe, N.

    2016-01-01

    In this thesis, I study coupled poroelastic waves and electromagnetic fields in layered media. The focus is two-fold:
    1. Increase the theoretical and physical understanding of the seismo-electromagnetic phenomenon by analytically-based numerical modeling.
    2. Investigate the potential of

  8. Storage and retrieval of electromagnetic waves with orbital angular momentum via plasmon-induced transparency.

    Science.gov (United States)

    Bai, Zhengyang; Xu, Datang; Huang, Guoxiang

    2017-01-23

    We propose a scheme to realize the storage and retrieval of high-dimensional electromagnetic waves with orbital angular momentum (OAM) via plasmon-induced transparency (PIT) in a metamaterial, which consists of an array of meta-atoms constructed by a metallic structure loaded with two varactors. We show that due to PIT effect the system allows the existence of shape-preserving dark-mode plasmonic polaritons, which are mixture of electromagnetic-wave modes and dark oscillatory modes of the meta-atoms and may carry various OAMs. We demonstrate that the slowdown, storage and retrieval of multi-mode electromagnetic waves with OAMs can be achieved through the active manipulation of a control field. Our work raises the possibility for realizing PIT-based spatial multi-mode memory of electromagnetic waves and is promising for practical application of information processing with large capacity by using room-temperature metamaterials.

  9. Simulation study of localization of electromagnetic waves in two-dimensional random dipolar systems.

    Science.gov (United States)

    Wang, Ken Kang-Hsin; Ye, Zhen

    2003-12-01

    We study the propagation and scattering of electromagnetic waves by random arrays of dipolar cylinders in a uniform medium. A set of self-consistent equations, incorporating all orders of multiple scattering of the electromagnetic waves, is derived from first principles and then solved numerically for electromagnetic fields. For certain ranges of frequencies, spatially localized electromagnetic waves appear in such a simple but realistic disordered system. Dependence of localization on the frequency, radiation damping, and filling factor is shown. The spatial behavior of the total, coherent, and diffusive waves is explored in detail, and found to comply with a physical intuitive picture. A phase diagram characterizing localization is presented, in agreement with previous investigations on other systems.

  10. Attenuation of an electromagnetic wave by charged dust particles in a sandstorm.

    Science.gov (United States)

    Xie, Li; Li, Xingcai; Zheng, Xiaojing

    2010-12-10

    We calculate the light scattering properties of the partially charged dust particles with the Mie theory for electromagnetic waves with different frequencies, and the attenuation coefficients of an electromagnetic wave propagating in a sandstorm are also calculated. The results show that the electric charges distributed on the sand surface have a significant effect on the attenuation of the electromagnetic wave, especially for a frequency lower than 40 GHz, and attenuation coefficients increase with the magnitude of charges carried by the dust particles (expressed by the charge-to-mass ratio in this paper). For the higher frequency electromagnetic wave, such as visible light, the effect of charges carried by sand particles on its attenuation is very little, which can be ignored.

  11. Reduced Graphene Oxide Functionalized with Cobalt Ferrite Nanocomposites for Enhanced Efficient and Lightweight Electromagnetic Wave Absorption

    National Research Council Canada - National Science Library

    Ding, Yi; Liao, Qingliang; Liu, Shuo; Guo, Huijing; Sun, Yihui; Zhang, Guangjie; Zhang, Yue

    2016-01-01

    ...) as a novel type of electromagnetic wave (EW) absorbing materials was successfully prepared by a three-step chemical method including hydrothermal synthesis, annealing process and mixing with paraffin...

  12. Modulation of coherence of vectorial electromagnetic waves in the Young interferometer.

    Science.gov (United States)

    Luis, Alfredo

    2008-07-01

    We show the modulation of coherence for vectorial electromagnetic waves taking place in the interference plane of a Young interferometer. The amplitude of modulation is determined by the polarization properties at the slits.

  13. Exact solutions of the Heisenberg equations of the relativistic electron in an external electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Barut, A.O. (Colorado Univ., Boulder (USA). Dept. of Physics); Oezaltin, O.; Uenal, N. (Dicle Univ., Diyarbakir (Turkey). Dept. of Physics)

    1985-01-01

    The Heisenberg equations for the Dirac electron in an external electromagnetic plane wave have been solved exactly in terms of incomplete ..gamma..-functions. As a special case the solution for a crossed constant electric and magnetic field is given.

  14. Scattering of Electromagnetic Waves by Many Nano-Wires

    Directory of Open Access Journals (Sweden)

    Alexander G. Ramm

    2013-07-01

    Full Text Available Electromagnetic wave scattering by many parallel to the z−axis, thin, impedance, parallel, infinite cylinders is studied asymptotically as a → 0. Let Dm be the cross-section of the m−th cylinder, a be its radius and xˆm = (xm1, xm2 be its center, 1 ≤ m ≤ M , M =   M (a. It is assumed that the points, xˆm, are distributed, so that N (∆  = (1 / 2πa * ∫∆ N (xˆdxˆ[1 + o(1], where N (∆ is the number of points, xˆm, in an arbitrary open subset, ∆, of the plane, xoy. The function, N (xˆ ≥ 0, is a continuous function, which an experimentalist can choose. An equation for the self-consistent (effective field is derived as a → 0. A formula is derived for the refraction coefficient in the medium in which many thin impedance cylinders are distributed. These cylinders may model nano-wires embedded in the medium. One can produce a desired refraction coefficient of the new medium by choosing a suitable boundary impedance of the thin cylinders and their distribution law.

  15. Controlling Energy Radiations of Electromagnetic Waves via Frequency Coding Metamaterials.

    Science.gov (United States)

    Wu, Haotian; Liu, Shuo; Wan, Xiang; Zhang, Lei; Wang, Dan; Li, Lianlin; Cui, Tie Jun

    2017-09-01

    Metamaterials are artificial structures composed of subwavelength unit cells to control electromagnetic (EM) waves. The spatial coding representation of metamaterial has the ability to describe the material in a digital way. The spatial coding metamaterials are typically constructed by unit cells that have similar shapes with fixed functionality. Here, the concept of frequency coding metamaterial is proposed, which achieves different controls of EM energy radiations with a fixed spatial coding pattern when the frequency changes. In this case, not only different phase responses of the unit cells are considered, but also different phase sensitivities are also required. Due to different frequency sensitivities of unit cells, two units with the same phase response at the initial frequency may have different phase responses at higher frequency. To describe the frequency coding property of unit cell, digitalized frequency sensitivity is proposed, in which the units are encoded with digits "0" and "1" to represent the low and high phase sensitivities, respectively. By this merit, two degrees of freedom, spatial coding and frequency coding, are obtained to control the EM energy radiations by a new class of frequency-spatial coding metamaterials. The above concepts and physical phenomena are confirmed by numerical simulations and experiments.

  16. Geodetic refraction effects of electromagnetic wave propagation through the atmosphere

    CERN Document Server

    1984-01-01

    With very few exceptions, geodetic measurements use electro­ magnetic radiation in order to measure directions, distances, time delays, and Doppler frequency shifts, to name the main ter­ restrial and space observables. Depending on the wavelength of the radiation and the purpose of the measurements, the follow­ ing parameters of the electromagnetic wave are measured: ampli­ tude, phase, angle-of-arrival, polarisation and frequency. Ac­ curate corrections have to be applied to the measurements in order to take into account the effects of the intervening medium between transmitter and receiver. The known solutions use at­ mospheric models, special observation programs, remote sensing techniques and instrumental methods. It has been shown that the effects of the earth's atmospheric envelope present a fundamental limitation to the accuracy and precision of geodetic measurements. This applies equally to ter­ restrial and space applications. Instrumental accuracies are al­ ready below the atmospherically i...

  17. Impact of Mobile Phone Electromagnetic Waves on Brainwaves

    Directory of Open Access Journals (Sweden)

    Fu-Chien Kao

    2015-07-01

    Full Text Available In the era of wireless communication, cellular phone becomes an indispensable accessory to most people. People use cellular phone to interact with others, perform commercial and financial transactions, or conducting recreational activities, etc. The advance in wireless technology and escalate of broadband networks not only flourish communications industry and application service providers but also encourage people perform prolonged wireless network activities under the risk of over exposing themselves in long term high frequency electromagnetic waves. For example, some people conduct excessive phone-trading activities, as it is necessary to the job, and some people exercise the non-stop e-learning or recreation activities on mobile devices with long hours. However, would prolonged exposure to high frequency EMW environment bring adverse effects on human health? This research from the perspective of cognitive neuroscience investigates the effect of EMW from cellular phone to the energy distribution of human brainwave characteristic band by examine brainwave changes of test subjects when exposing to high frequency EMW environment. Experiment uses left ear and right ear to answer the phone separately. The calling session is divided into three stages: the instant of call connection, during the call, and after the call. On each ear, the brainwave signal of each calling stage is extracted and analyzed. The experiment shows at the instant of call connection stage, resulting maximum EMW strength, having extreme effect on the energy distribution of the human brainwave characteristic band, and causing severe changes on the energy of human brainwave.

  18. Hydrothermal Synthesis of Nanooctahedra MnFe₂O₄ onto the Wood Surface with Soft Magnetism, Fire Resistance and Electromagnetic Wave Absorption.

    Science.gov (United States)

    Wang, Hanwei; Yao, Qiufang; Wang, Chao; Ma, Zhongqing; Sun, Qingfeng; Fan, Bitao; Jin, Chunde; Chen, Yipeng

    2017-05-23

    In this study, nanooctahedra MnFe₂O₄ were successfully deposited on a wood surface via a low hydrothermal treatment by hydrogen bonding interactions. As-prepared MnFe₂O₄/wood composite (MW) had superior performance of soft magnetism, fire resistance and electromagnetic wave absorption. Among them, small hysteresis loops and low coercivity (magnetization-field curve of MW with saturation magnetization of 28.24 emu/g, indicating its excellent soft magnetism. The MW also exhibited a good fire-resistant property due to its initial burning time at 20 s; while only 6 s for the untreated wood (UW) in combustion experiments. Additionally, this composite revealed good electromagnetic wave absorption with a minimum reflection loss of -9.3 dB at 16.48 GHz. Therefore, the MW has great potential in the fields of special decoration and indoor electromagnetic wave absorbers.

  19. The influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction

    OpenAIRE

    Forsberg, Mats; Papadopoulos, Demetrios; Brodin, Gert

    2010-01-01

    The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the quantum electrodynamical (QED) effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered d...

  20. Characterization of porous construction materials using electromagnetic radar wave

    Science.gov (United States)

    Lai, Wallace Wai Lok

    This thesis reports the effort of characterizing three porous construction materials (i.e. concrete, asphalt and soils) and the establishment and formulation of novel unified constitutive models by utilizing electromagnetic (EM) radar wave. An important outcome of this research is that the studied materials were assigned successfully into their rightful positions corresponding to the different regimes governed by three EM wave properties and two engineering/geological properties of the materials. The former refers to the real part of complex dielectric permittivity (epsilon'), energy attenuation and peak-frequency drift. The latter refers to porosity and permeability determined with forward models or conventional testing techniques. In soil and asphalt, the material characterization was achieved by a novel inhouse developed method called Cyclic Moisture Variation Technique (CMVT). The technique is termed cyclic because the porous materials were subjected to change from partially saturated states to fully saturated state (i.e. permeation), and vice versa (i.e. de-watering). With CMVT, water was used as an enhancer or a tracer to differentiate the studied materials which are otherwise difficult when they are dry. Soils and asphalt with different textures were characterized by different curve families exhibited in the relationship between epsilon' and degrees of water saturation (SW). In particular, these curve families were divided into three regions: slow-climbing region in very low SW, fast-climbing region in intermediate SW and another slow-climbing region at high S W. When data obtained from the permeation and de-watering cycles was compared, dielectric hysteresis was observed, but rarely reported in the field of ground penetrating radar (GPR). Different curing histories affect both porosity and pore size distribution within mature concrete. By injecting pressurized water into concrete specimens, different concrete curing histories was back-tracked through the

  1. Electromagnetic Shielding Efficiency Measurement of Composite Materials

    Science.gov (United States)

    Dřínovský, J.; Kejík, Z.

    2009-01-01

    This paper deals with the theoretical and practical aspects of the shielding efficiency measurements of construction composite materials. This contribution describes an alternative test method of these measurements by using the measurement circular flange. The measured results and parameters of coaxial test flange are also discussed. The measurement circular flange is described by measured scattering parameters in the frequency range from 9 kHz up to 1 GHz. The accuracy of the used shielding efficiency measurement method was checked by brass calibration ring. The suitability of the coaxial test setup was also checked by measurements on the EMC test chamber. This data was compared with the measured data on the real EMC chamber. The whole measurement of shielding efficiency was controlled by the program which runs on a personal computer. This program was created in the VEE Pro environment produced by © Agilent Technology.

  2. Fe3O4@polyaniline yolk–shell micro/nanospheres as bifunctional materials for lithium storage and electromagnetic wave absorption

    DEFF Research Database (Denmark)

    Wang, Xiaoliang; Zhang, Minwei; Zhao, Jianming

    2017-01-01

    deliver superior capacity, better cycling stability and rate capability than those of bare Fe3O4 micro/nanospheres and Fe3O4/PANI core-shell (FPcs) electrodes. Moreover, FPys also exhibits excellent electromagnetic wave absorption performance when comparing to the synthesized Fe3O4-based electromagnetic......Unique Fe3O4/polyaniline (PANI) composite with yolk-shell micro/nanostructure (FPys) has been successfully synthesized by a facile silica-assisted in-situ polymerization and subsequent etching strategy. The structural and compositional studies of the FPys composites are performed by employing X...

  3. Optimal Design of Electromagnetic Acoustic Transducer Used to Generate Lamb Wave

    Directory of Open Access Journals (Sweden)

    Yan LIU

    2014-01-01

    Full Text Available Electromagnetic ultrasonic transducer is the core component of the electromagnetic ultrasonic testing equipment. This paper establishes a three-dimensional model of the electromagnetic ultrasonic transducer used to generate Lamb wave, then by uniform design experiment and finite element analysis, the paper obtains the law between the eddy current density, the conductor width, length of the coil, the lift off distance, and the permanent magnets thickness. The law is verified by the experiment. It provides an overall principle for the optimal design of electromagnetic ultrasonic transducer.

  4. Broadband low‐frequency electromagnetic waves in the inner magnetosphere

    National Research Council Canada - National Science Library

    Chaston, C. C; Bonnell, J. W; Kletzing, C. A; Hospodarsky, G. B; Wygant, J. R; Smith, C. W

    2015-01-01

    A prominent yet largely unrecognized feature of the inner magnetosphere associated with particle injections, and more generally geomagnetic storms, is the occurrence of broadband electromagnetic field...

  5. Descriptive study of electromagnetic wave distribution for various seating positions: using digital textbooks.

    Science.gov (United States)

    Seomun, GyeongAe; Kim, YoungHwan; Lee, Jung-Ah; Jeong, KwangHoon; Park, Seon-A; Kim, Miran; Noh, Wonjung

    2014-04-01

    To better understand environmental electromagnetic wave exposure during the use of digital textbooks by elementary school students, we measured numeric values of the electromagnetic fields produced by tablet personal computers (TPCs). Specifically, we examined the distribution of the electromagnetic waves for various students' seating positions in an elementary school that uses digital textbooks. Electric and magnetic fields from TPCs were measured using the HI-3603 Visual Display Terminal/ Very Low Frequency (VDT/VLF) radiation measurement system. Electromagnetic field values from TPCs measured at a student's seat and at a teacher's computer were deemed not harmful to health. However, electromagnetic field values varied based on the distance between students, other electronic devices such as a desktop computers, and student posture while using a TPC. Based on these results, it is necessary to guide students to observe proper posture and to arrange seats at an appropriate distance in the classroom.

  6. Effects of chronic exposure to electromagnetic waves on the auditory system.

    Science.gov (United States)

    Özgür, Abdulkadir; Tümkaya, Levent; Terzi, Suat; Kalkan, Yıldıray; Erdivanlı, Özlem Çelebi; Dursun, Engin

    2015-08-01

    The results support that chronic electromagnetic field exposure may cause damage by leading to neuronal degeneration of the auditory system. Numerous researches have been done about the risks of exposure to the electromagnetic fields that occur during the use of these devices, especially the effects on hearing. The aim of this study is to evaluate the effects of the electromagnetic waves emitted by the mobile phones through the electrophysiological and histological methods. Twelve adult Wistar albino rats were included in the study. The rats were divided into two groups of six rats. The study group was exposed to the electromagnetic waves over a period of 30 days. The control group was not given any exposure to the electromagnetic fields. After the completion of the electromagnetic wave application, the auditory brainstem responses of both groups were recorded under anesthesia. The degeneration of cochlear nuclei was graded by two different histologists, both of whom were blinded to group information. The histopathologic and immunohistochemical analysis showed neuronal degeneration signs, such as increased vacuolization in the cochlear nucleus, pyknotic cell appearance, and edema in the group exposed to the electromagnetic fields compared to the control group. The average latency of wave in the ABR was similar in both groups (p > 0.05).

  7. Electromagnetic counterparts to structured jets from gravitational wave detected mergers

    Science.gov (United States)

    Lamb, Gavin P.; Kobayashi, Shiho

    2017-12-01

    We show the peak magnitude for orphan afterglows from the jets of gravitational wave (GW) detected black hole/neutron star - neutron star (BH/NS-NS) mergers highly depend on the jet half-opening angle θj. Short γ-ray bursts (GRBs) with a homogeneous jet structure and θj > 10°, the orphan afterglow viewed at the typical inclination for a GW detected event, 38°, are brighter at optical frequencies than the comparable macronova emission. Structured jets, where the energetics and Lorentz factor Γ vary with angle from the central axis, may have low-Γ components where the prompt emission is suppressed; GW electromagnetic (EM) counterparts may reveal a population of failed-GRB orphan afterglows. Using a Monte Carlo method assuming an NS-NS detection limit we show the fraction of GW-EM counterparts from homogeneous, two-component, power-law structured and Gaussian jets where the variable structure models include a wide low energy and Γ component: for homogeneous jets, with a θj = 6° and typical short GRB parameters, we find r-band magnitude mr ≤ 21 counterparts for ∼13.6 per cent of GW detected mergers; where jet structure extends to a half-opening angle of 25°, two-component jets produce mr ≤ 21 counterparts in ∼30 per cent of GW detected mergers, power-law structured-jets result in ∼37 per cent and Gaussian jets with our parameters ∼13 per cent. We show the features in the light curves from orphan afterglows can be used to indicate the presence of extended structure.

  8. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    Science.gov (United States)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-01-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

  9. Elastic metamaterials for tuning circular polarization of electromagnetic waves.

    Science.gov (United States)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

    2016-06-20

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  10. Synthesis and electromagnetic properties of PANI/PVP/CIP core–shell composites

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jihai [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); No. 59 Research Institute of China Ordnance Industry, Chongqing 400039 (China); Ma, Li, E-mail: mlsys607@126.com [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Tian, Nan; Gan, Mengyu; Xu, Fenfang; Zeng, Jun; Tu, Ying [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China)

    2014-08-01

    Highlights: • PANI/PVP/CIP core–shell composite was prepared, where PVP can hinder aggregation of CIP and PANI/PVP/CIP composites. • Core–shell structure increases absorbent interface, benefiting reflection, scattering and electromagnetic wave absorption. • PANI/PVP/CIP core–shell composites show better electromagnetic matching and microwave absorption in a wider frequency range. - Abstract: The polyaniline/polyvinylpyrrolidone/carbonyl iron powder (PANI/PVP/CIP) core–shell composites were prepared by in-situ polymerization in the PVP aqueous solution using toluenesulfonic acid (TSA) as dopant and ammonium persulfate (APS) as oxidant. The PANI/PVP/CIP was systematically investigated using scanning electron microscopy (SEM), FT-IR spectroscopy, electrochemical workstation, thermogravimetry analysis (TGA) and vector network analyzer. The results showed that the PANI/PVP can dramatically improve corrosion resistance of CIP. Compared with pure CIP, the PANI/PVP/CIP composites exhibited better impedance match and excellent microwave absorption properties. The reflection loss was found to <–10 dB in the 27.3–39.5 GHz range at thickness of 1.1 mm, and the minimum reflection loss of −15.28 dB was observed at 29.47 GHz with a matching thickness of 1.2 mm. A possible mechanism of the improved microwave absorption properties of the core–shell structure was obtained.

  11. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    Science.gov (United States)

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  12. Scalable Fabrication of Natural-Fiber Reinforced Composites with Electromagnetic Interference Shielding Properties by Incorporating Powdered Activated Carbon.

    Science.gov (United States)

    Xia, Changlei; Zhang, Shifeng; Ren, Han; Shi, Sheldon Q; Zhang, Hualiang; Cai, Liping; Li, Jianzhang

    2015-12-25

    Kenaf fiber-polyester composites incorporated with powdered activated carbon (PAC) were prepared using the vacuum-assisted resin transfer molding (VARTM) process. The product demonstrates the electromagnetic interference (EMI) shielding function. The kenaf fibers were retted in a pressured reactor to remove the lignin and extractives in the fiber. The PAC was loaded into the freshly retted fibers in water. The PAC loading effectiveness was determined using the Brunauer-Emmett-Teller (BET) specific surface area analysis. A higher BET value was obtained with a higher PAC loading. The transmission energies of the composites were measured by exposing the samples to the irradiation of electromagnetic waves with a variable frequency from 8 GHz to 12 GHz. As the PAC content increased from 0% to 10.0%, 20.5% and 28.9%, the EMI shielding effectiveness increased from 41.4% to 76.0%, 87.9% and 93.0%, respectively. Additionally, the EMI absorption increased from 21.2% to 31.7%, 44.7% and 64.0%, respectively. The ratio of EMI absorption/shielding of the composite at 28.9% of PAC loading was increased significantly by 37.1% as compared with the control sample. It was indicated that the incorporation of PAC into the composites was very effective for absorbing electromagnetic waves, which resulted in a decrease in secondary electromagnetic pollution.

  13. Scalable Fabrication of Natural-Fiber Reinforced Composites with Electromagnetic Interference Shielding Properties by Incorporating Powdered Activated Carbon

    Directory of Open Access Journals (Sweden)

    Changlei Xia

    2015-12-01

    Full Text Available Kenaf fiber—polyester composites incorporated with powdered activated carbon (PAC were prepared using the vacuum-assisted resin transfer molding (VARTM process. The product demonstrates the electromagnetic interference (EMI shielding function. The kenaf fibers were retted in a pressured reactor to remove the lignin and extractives in the fiber. The PAC was loaded into the freshly retted fibers in water. The PAC loading effectiveness was determined using the Brunauer-Emmett-Teller (BET specific surface area analysis. A higher BET value was obtained with a higher PAC loading. The transmission energies of the composites were measured by exposing the samples to the irradiation of electromagnetic waves with a variable frequency from 8 GHz to 12 GHz. As the PAC content increased from 0% to 10.0%, 20.5% and 28.9%, the EMI shielding effectiveness increased from 41.4% to 76.0%, 87.9% and 93.0%, respectively. Additionally, the EMI absorption increased from 21.2% to 31.7%, 44.7% and 64.0%, respectively. The ratio of EMI absorption/shielding of the composite at 28.9% of PAC loading was increased significantly by 37.1% as compared with the control sample. It was indicated that the incorporation of PAC into the composites was very effective for absorbing electromagnetic waves, which resulted in a decrease in secondary electromagnetic pollution.

  14. Teaching the Common Aspects in Mechanical, Electromagnetic and Quantum Waves at Interfaces and Waveguides

    Science.gov (United States)

    Rojas, R.; Robles, P.

    2011-01-01

    We discuss common features in mechanical, electromagnetic and quantum systems, supporting identical results for the transmission and reflection coefficients of waves arriving perpendicularly at a plane interface. Also, we briefly discuss the origin of special notions such as refractive index in quantum mechanics, massive photons in wave guides and…

  15. Shaping 3D Path of Electromagnetic Waves Using Gradient-Refractive-Index Metamaterials.

    Science.gov (United States)

    Jiang, Wei Xiang; Ge, Shuo; Han, Tiancheng; Zhang, Shuang; Mehmood, Muhammad Qasim; Qiu, Cheng-Wei; Cui, Tie Jun

    2016-08-01

    An all-dielectric semispherical lens with functions in shaping 3D wave-propagation paths is proposed and experimentally verified. When radiation sources are placed in the central region, the lens behaves as a magnifying device to resolve the sources in subwavelength scale; while when the electromagnetic waves impinge on the semispherical lens from outside, they will be guided spirally inward.

  16. The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence

    Science.gov (United States)

    Smith, Glenn S.

    2012-01-01

    In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…

  17. Electromagnetic Waves with Frequencies Near the Local Proton Gryofrequency: ISEF-3 1 AU Observations

    Science.gov (United States)

    Tsurutani, B.

    1993-01-01

    Low Frequency electromagnetic waves with periods near the local proton gyrofrequency have been detected near 1 AU by the magnetometer onboard ISEE-3. For these 1 AU waves two physical processes are possible: solar wind pickup of nuetral (interstellar?) particles and generation by relativistic electron beams propagating from the Sun.

  18. geometric optics and WKB method for electromagnetic wave propagation in an inhomogeneous plasma near cutoff

    Energy Technology Data Exchange (ETDEWEB)

    Light, Max Eugene [Los Alamos National Laboratory

    2017-04-13

    This report outlines the theory underlying electromagnetic (EM) wave propagation in an unmagnetized, inhomogeneous plasma. The inhomogeneity is given by a spatially nonuniform plasma electron density ne(r), which will modify the wave propagation in the direction of the gradient rne(r).

  19. Shock Wave Structure in Particulate Composites

    Science.gov (United States)

    Rauls, Michael; Ravichandran, Guruswami

    2015-06-01

    Shock wave experiments are conducted on a particulate composite consisting of a polymethyl methacrylate (PMMA) matrix reinforced by glass beads. Such a composite with an impedance mismatch of 4.3 closely mimics heterogeneous solids of interest such as concrete and energetic materials. The composite samples are prepared using a compression molding process. The structure and particle velocity rise times of the shocks are examined using forward ballistic experiments. Reverse ballistic experiments are used to track how the interface density influences velocity overshoot above the steady state particle velocity. The effects of particle size (0.1 to 1 mm) and volume fraction of glass beads (30-40%) on the structure of the leading shock wave are investigated. It is observed that the rise time increases with increasing particle size and scales linearly for the range of particle sizes considered here. Results from numerical simulations using CTH are compared with experimental results to gain insights into wave propagation in heterogeneous particulate composites.

  20. Condition for far-zone spectral isotropy of an electromagnetic light wave on weak scattering.

    Science.gov (United States)

    Wang, Tao; Zhao, Daomu

    2011-02-01

    The far-zone spectral isotropy of an electromagnetic light wave on scattering has been discussed. It is shown that a sufficient condition for the far-zone spectral isotropy of an electromagnetic light wave on scattering can be expressed by the following two requirements: the two-point correlation function of the dielectric susceptibility of the scattering medium obeys the so-called scaling law, and the normalized spectrum of the incident light wave has the same distribution along the two perpendicular directions.

  1. Finite element analysis of electromagnetic propagation in an absorbing wave guide

    Science.gov (United States)

    Baumeister, Kenneth J.

    1986-01-01

    Wave guides play a significant role in microwave space communication systems. The attenuation per unit length of the guide depends on its construction and design frequency range. A finite element Galerkin formulation has been developed to study TM electromagnetic propagation in complex two-dimensional absorbing wave guides. The analysis models the electromagnetic absorptive characteristics of a general wave guide which could be used to determine wall losses or simulate resistive terminations fitted into the ends of a guide. It is believed that the general conclusions drawn by using this simpler two-dimensional geometry will be fundamentally the same for other geometries.

  2. Electromagnetic wave propagation in a random distribution of C{sub 60} molecules

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah, Iran and Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

    2014-10-15

    Propagation of electromagnetic waves in a random distribution of C{sub 60} molecules are investigated, within the framework of the classical electrodynamics. Electronic excitations over the each C{sub 60} molecule surface are modeled by a spherical layer of electron gas represented by two interacting fluids, which takes into account the different nature of the π and σ electrons. It is found that the present medium supports four modes of electromagnetic waves, where they can be divided into two groups: one group with shorter wavelength than the light waves of the same frequency and the other with longer wavelength than the free-space radiation.

  3. Electromagnetic response of the composites containing chemically modified carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Nemilentsau, A M; Shuba, M V; D' yachkov, P N; Slepyan, G Y A; Kuzhir, P P; Maksimenko, S A, E-mail: andrei.nemilentsau@gmail.co

    2010-11-01

    We demonstrate theoretically that the chemical modification of the bundles and composites containing mixture of semiconducting and metallic single-wall carbon nanotubes (SWNTs) leads to the substantial enhancement of the characteristics of their electromagnetic response in the terahertz (THz) frequency range. Boron and nitrogen doping is used to illustrate the effect. In particular, frequencies of antenna resonances in the bundles containing doped SWNTs are shifted to the blue in comparison to the ones in the bundles containing the same number of pristine SWNTs. Moreover, doping increases the resonant values of the bundles polarizability. Enhancement of the conductivity of the composite containing doped SWNTs is also demonstrated. The origin of the behavior is the metallization of the chemically modified semiconducting SWNTs in the bundles and composites due to the injection of the additional charge carriers.

  4. Ion hole formation and nonlinear generation of electromagnetic ion cyclotron waves: THEMIS observations

    Science.gov (United States)

    Shoji, Masafumi; Miyoshi, Yoshizumi; Katoh, Yuto; Keika, Kunihiro; Angelopoulos, Vassilis; Kasahara, Satoshi; Asamura, Kazushi; Nakamura, Satoko; Omura, Yoshiharu

    2017-09-01

    Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyromotion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion holes in the distribution function and the resulting nonlinear EMIC wave evolution from Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave-particle interactions, which are identified by a computer simulation in this study.

  5. Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave-current coupled model

    Science.gov (United States)

    Tao, Xie; Shang-Zhuo, Zhao; William, Perrie; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-06-01

    To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave-current model is derived, based on the mechanism of wave-current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave-current interaction effect of the ocean current is much stronger than that of the nonlinear wave-wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service.

  6. Excitation of Surface Electromagnetic Waves on Railroad Rail

    Science.gov (United States)

    1978-03-31

    UMTA's Office of Rail Technology research programs aim to improve urban rail transportation systems safety. This rail-transit research study attempts to develop an onboard, separate and independent obstacle-detection system--Surface Electromagnetic W...

  7. Absorbing boundary conditions for low group velocity electromagnetic waves in photonic crystals.

    Science.gov (United States)

    Askari, Murtaza; Momeni, Babak; Reinke, Charles M; Adibi, Ali

    2011-03-20

    We present an efficient method for the absorption of slow group velocity electromagnetic waves in photonic crystal waveguides (PCWs). We show that adiabatically matching the low group velocity waves to high group velocity waves of the PCW and extending the PCW structure into the perfectly matched layer (PML) region results in a 15 dB reduction of spurious reflections from the PML. We also discuss the applicability of this method to structures other than PCWs.

  8. Modulation of a compressional electromagnetic wave in a magnetized electron-positron quantum plasma.

    Science.gov (United States)

    Amin, M R

    2015-09-01

    Amplitude modulation of a compressional electromagnetic wave in a strongly magnetized electron-positron pair plasma is considered in the quantum magnetohydrodynamic regime. The important ingredients of this study are the inclusion of the external strong magnetic field, Fermi quantum degeneracy pressure, particle exchange potential, quantum diffraction effects via the Bohm potential, and dissipative effect due to collision of the charged carriers. A modified-nonlinear Schödinger equation is developed for the compressional magnetic field of the electromagnetic wave by employing the standard reductive perturbation technique. The linear and nonlinear dispersions of the electromagnetic wave are discussed in detail. For some parameter ranges, relevant to dense astrophysical objects such as the outer layers of white dwarfs, neutron stars, and magnetars, etc., it is found that the compressional electromagnetic wave is modulationally unstable and propagates as a dissipated electromagnetic wave. It is also found that the quantum effects due to the particle exchange potential and the Bohm potential are negligibly small in comparison to the effects of the Fermi quantum degeneracy pressure. The numerical results on the growth rate of the modulation instability is also presented.

  9. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals

    Science.gov (United States)

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-01

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 1 04 s . This uncertainty can be suppressed by a factor of ˜1 010, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ -ray bursts and fast radio bursts.

  10. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

    Science.gov (United States)

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-03

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4}  s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.

  11. A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

    Science.gov (United States)

    Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

    2012-01-01

    Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

  12. Second-harmonic generation of cylindrical electromagnetic waves propagating in an inhomogeneous and nonlinear medium.

    Science.gov (United States)

    Xiong, Hao; Si, Liu-Gang; Ding, Chunling; Yang, Xiaoxue; Wu, Ying

    2012-01-01

    A general description of cylindrical electromagnetic waves propagating in nonlinear and inhomogeneous media is given by deducing cylindrical coupled-wave equations. Based on the cylindrical coupled-wave equations, we analyze second-harmonic generation (SHG) of some special cases of inhomogeneity, and find that the inhomogeneity of the first- and second-order polarization can influence the amplitude of the SHG. From a different point of view, exact solutions of cylindrical electromagnetic waves propagating in a nonlinear medium with a special case of inhomogeneity have been obtained previously. We show that cylindrical SHG in an inhomogeneous and nonlinear medium can also be deduced from exact solutions. As verification, we compare the results obtained from the two different methods and find that descriptions of SHG by the coupled-wave equations are in good agreement with the exact solutions.

  13. Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

    CERN Document Server

    Lekner, John

    2016-01-01

    This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

  14. Iterative Computational Scheme of Studying Electromagnetic Wave Propagation through Dielectric Thin Film Medium

    Directory of Open Access Journals (Sweden)

    E Ugwu

    2016-09-01

    Full Text Available We present an approach to the computation of electromagnetic wave propagation through a dielectric thin film medium using iterative scheme. We used the Green's function technique involving some necessary boundary condition to solve the scalar wave equation. Non-vectorial aspects of the propagating wave through the thin film resulting from the film orientation were considered. The iterative numerical scheme based on the parallel use of Lippmann-Schwinger and Dyson's equations is demonstrated and used judiciously in the computation. The influence of the numerical parameters such as Green's function, thickness of the thin film, dielectric perturbation, Δεp(z and mesh size, Np on the propagating wave for three region of electromagnetic wave were clearly assessed.

  15. Transversality of electromagnetic waves in the calculus-based introductory physics course

    Energy Technology Data Exchange (ETDEWEB)

    Burko, Lior M [Department of Physics and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 38599 (United States)

    2008-11-15

    Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by instructors of such courses. Here, we discuss two physical arguments (based on polarization experiments and on lack of monopole electromagnetic radiation) and the full argument for the transversality of (plane) electromagnetic waves based on the integral Maxwell equations. We also show, at a level appropriate for the introductory course, why the electric and magnetic fields in a wave are in phase and the relation of their magnitudes.

  16. Parametric study of electromagnetic waves propagating in absorbing curved S ducts

    Science.gov (United States)

    Baumeister, Kenneth J.

    1989-01-01

    A finite-element Galerkin formulation has been developed to study attenuation of transverse magnetic (TM) waves propagating in two-dimensional S-curved ducts with absorbing walls. In the frequency range where the duct diameter and electromagnetic wave length are nearly equal, the effect of duct length, curvature (duct offset), and absorber wall thickness was examined. For a given offset in the curved duct, the length of the S-duct was found to significantly affect both the absorptive and reflective characteristics of the duct. For a straight and a curved duct with perfect electric conductor terminations, power attenuation contours were examined to determine electromagnetic wall properties associated with maximum input signal absorption. Offset of the S-duct was found to significantly affect the value of the wall permittivity associated with the optimal attenuation of the incident electromagnetic wave.

  17. Estimation of Aircraft Attitude/Heading Based on the Polarization of Electromagnetic Waves

    Directory of Open Access Journals (Sweden)

    Sun Hong-mei

    2013-12-01

    Full Text Available This paper illustrates the full use of an orthogonal decoupling signal model to describe the 3-D construction of polarized electromagnetic waves. The maximum likelihood method and MUSIC algorithm were introduced into the parameter estimation of partially polarized waves. Attitude reference information for an aircraft that was calibrated by an information base station was delivered by polarized electromagnetic waves. Through receiving and processing the information of the aircraft, a single electromagnetic vector sensor can acquire the aircraft attitude in a geographic coordinate system. Differing from the triangle calculation method which relies on a multi-point measurement, the proposed method only needs a base station signal and a single receiver on the motion platform to realize the posture perception of aircraft. It can therefore serve as a substitute for aircraft attitude navigation and aircraft heading navigation. The introduction of the motion platform attitude estimation algorithm provides a technology support for engineering applications.

  18. Links between extremely high frequency electromagnetic waves and their biological manifestations

    Directory of Open Access Journals (Sweden)

    Anton Emil

    2015-01-01

    Full Text Available In this mini-review, we describe some of the latest facts regarding the generation of condensed base phonons by biological entities, initially described by the renowned contemporary physicist, Nobel laureate, Herbert Fröhlich, who proposed a new biophysical interaction mechanism between extremely high frequency electromagnetic waves and the biological environment. As we will show, this extremely low intensity millimeter therapy crystallizes as an important new method, universal and effective in the management of diseases with different etiologies. Moreover, the existence of internal electromagnetic fields generated by biological entities, as well as external electromagnetic fields, are essential for understanding the electromagnetic-biological effect. In fact, it is estimated that at present millimeter-wave therapy is used for the management of more than 120 diseases in cardiology, neurology, oncology, gynecology, urology, gastroenterology, surgery, pharmacology and pediatrics. However, so far there is still no consensus regarding the interaction between extremely high frequency/extremely low intensity electromagnetic waves and the biological environment at its different levels of organization. Thus, the present paper was intended to contribute to the development for the theory of millimeter-wave interaction with living biological entities.

  19. A statistical model for relativistic quantum fluids interacting with an intense electromagnetic wave

    Science.gov (United States)

    Mahajan, Swadesh M.; Asenjo, Felipe A.

    2016-05-01

    A statistical model for relativistic quantum fluids interacting with an arbitrary amplitude circularly polarized electromagnetic wave is developed in two steps. First, the energy spectrum and the wave function for a quantum particle (Klein Gordon and Dirac) embedded in the electromagnetic wave are calculated by solving the appropriate eigenvalue problem. The energy spectrum is anisotropic in the momentum K and reflects the electromagnetic field through the renormalization of the rest mass m to M =√{m2+q2A2 } . Based on this energy spectrum of this quantum particle plus field combination (QPF), a statistical mechanics model of the quantum fluid made up of these weakly interacting QPF is developed. Preliminary investigations of the formalism yield highly interesting results—a new scale for temperature, and fundamental modification of the dispersion relation of the electromagnetic wave. It is expected that this formulation could, inter alia, uniquely advance our understanding of laboratory as well as astrophysical systems where one encounters arbitrarily large electromagnetic fields.

  20. Electromagnetic Wave Excitation, Propagation, and Absorption in High Current Storage Rings

    Science.gov (United States)

    Novokhatski, A.; Seeman, J.; Sullivan, M.; Wienands, U.

    2016-04-01

    We analyze a variety of electromagnetic effects in storage rings with extremely high currents. Specifically, we discuss our experience in the operation of the PEP-II (SLAC B-factory). We present some outstanding and sometimes unpredictable effects of the behavior of electromagnetic waves excited by intense beams inside a vacuum chamber in storage rings. Although the impedance of the rings is usually designed to be small, intense high-current beams can still generate significant microwave power. This power can be enough to damage vacuum beam chamber elements, which may absorb electromagnetic waves. The most sensitive elements are RF seals, vacuum valves, shielded bellows, beam position monitor buttons, and ceramic tiles. Additionally, microwave heating leads to vacuum pressure spikes or even vacuum pressure instabilities that brings high detector background. Resonance excitation of the electromagnetic field may lead to a very high electric component amplitude that can cause breakdowns leading to sparks and discharges. Finally, high-power electromagnetic waves can be responsible for beam instabilities in the ring. Proper absorption of these generated waves may eliminate these effects. We feel our experience will be helpful in the design of new high current synchrotron light sources and storage rings.

  1. Microstructure, elastic and electromagnetic properties of epoxy-graphite composites

    Science.gov (United States)

    Bellucci, S.; Micciulla, F.; Levin, V. M.; Petronyuk, Yu. S.; Chernozatonskii, L. A.; Kuzhir, P. P.; Paddubskaya, A. G.; Macutkevic, J.; Pletnev, M. A.; Fierro, V.; Celzard, A.

    2015-06-01

    A set of epoxy resin-based composites filled with 0.25 - 2.0 wt.% of commercially available exfoliated graphite (EG) and thick graphene (TG), prepared by suspending EG particles in cyclohexane, and submitting the suspension to a series of grinding and ultrasonic dispersion steps, was produced. The microstructure of such epoxy-graphite composites has been studied by the impulse acoustic microscopy technique. According to acoustic microscopy data, exfoliated graphite microparticles have been well dispersed in the epoxy matrix. TG nanoflakes demonstrated persistent tendency to clustering and formation of agglomerates. The addition of graphite particles in small amount (0.25 - 2.0 wt.%) did not influence the bulk elastic properties of epoxy-graphite composite materials. Being extremely lightweight, 0.003 g cm-3, EG had a lower percolation threshold than TG, at the level of 1-1.5 wt.% against 2.1-3.2 wt.%, respectively. As a result, epoxy composites filled with 1.0-2.0 wt.% EG provided high electromagnetic (EM) interference shielding both at microwave and THz frequencies. In contrast, no significant influence of TG loading was observed at low weight fraction (up to 2 wt.%) on the EM performance of epoxy composites.

  2. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma.

    Science.gov (United States)

    Tejero, E M; Crabtree, C; Blackwell, D D; Amatucci, W E; Mithaiwala, M; Ganguli, G; Rudakov, L

    2015-12-09

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10(-6) times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth's plasma environment.

  3. Adiabatic description of capture into resonance and surfatron acceleration of charged particles by electromagnetic waves.

    Science.gov (United States)

    Artemyev, A V; Neishtadt, A I; Zelenyi, L M; Vainchtein, D L

    2010-12-01

    We present an analytical and numerical study of the surfatron acceleration of nonrelativistic charged particles by electromagnetic waves. The acceleration is caused by capture of particles into resonance with one of the waves. We investigate capture for systems with one or two waves and provide conditions under which the obtained results can be applied to systems with more than two waves. In the case of a single wave, the once captured particles never leave the resonance and their velocity grows linearly with time. However, if there are two waves in the system, the upper bound of the energy gain may exist and we find the analytical value of that bound. We discuss several generalizations including the relativistic limit, different wave amplitudes, and a wide range of the waves' wavenumbers. The obtained results are used for qualitative description of some phenomena observed in the Earth's magnetosphere. © 2010 American Institute of Physics.

  4. Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Wang

    2016-05-01

    Full Text Available Propagation characteristics of electromagnetic (EM waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.

  5. Condition for invariant spectrum of an electromagnetic wave scattered from an anisotropic random media.

    Science.gov (United States)

    Li, Jia; Wu, Pinghui; Chang, Liping

    2015-08-24

    Within the accuracy of the first-order Born approximation, sufficient conditions are derived for the invariance of spectrum of an electromagnetic wave, which is generated by the scattering of an electromagnetic plane wave from an anisotropic random media. We show that the following restrictions on properties of incident fields and the anisotropic media must be simultaneously satisfied: 1) the elements of the dielectric susceptibility matrix of the media must obey the scaling law; 2) the spectral components of the incident field are proportional to each other; 3) the second moments of the elements of the dielectric susceptibility matrix of the media are inversely proportional to the frequency.

  6. Breathers in Josephson junction ladders: Resonances and electromagnetic wave spectroscopy

    DEFF Research Database (Denmark)

    Miroshnichenko, A. E.; Flach, S.; Fistul, M.

    2001-01-01

    We present a theoretical study of the resonant interaction between dynamical localized states (discrete breathers) and linear electromagnetic excitations (EE's) in Josephson junction ladders. By making use of direct numerical simulations we find that such an interaction manifests itself by resonant...

  7. Interlevel absorption of electromagnetic waves by nanocrystal with divalent impurity

    Directory of Open Access Journals (Sweden)

    V. I Boichuk

    2014-06-01

    Full Text Available The energy spectrum of central divalent impurity is calculated using the effective mass approximation in a spherical quantum dot (QD. The dipole moment and oscillator strength of interlevel transition is defined. The dependence of linear absorption coefficient on the QD size and electromagnetic frequency is analyzed. The obtained results are compared with the results of univalent impurity.

  8. Absorption-Dominated Electromagnetic Wave Suppressor Derived from Ferrite-Doped Cross-Linked Graphene Framework and Conducting Carbon.

    Science.gov (United States)

    Biswas, Sourav; Arief, Injamamul; Panja, Sujit Sankar; Bose, Suryasarathi

    2017-01-25

    To minimize electromagnetic (EM) pollution, two key parameters, namely, intrinsic wave impedance matching and intense absorption of incoming EM radiation, must satisfy the utmost requirements. To target these requirements, soft conducting composites consisting of binary blends of polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) were designed with doped multiwalled carbon nanotubes (MWCNTs) and a three-dimensional cross-linked graphene oxide (GO) framework doped with ferrite nanoparticles. The doping of α-MnO2 onto the MWCNTs ensured intrinsic wave impedance matching in addition to providing conducting pathways, and the ferrite-doped cross-linked GO facilitated the enhanced attenuation of the incoming EM radiation. This unique combination of magnetodielectric coupling led to a very high electromagnetic shielding efficiency (SE) of -37 dB at 18 GHz, dominated by absorption-driven shielding. The promising results from the composites further motivated us to rationally stack individual composites into a multilayer architecture following an absorption-multiple reflection-absorption pathway. This resulted in an impressive SE of -57 dB for a thin shield of 0.9-mm thickness. Such a high SE indicates >99.999% attenuation of the incoming EM radiation, which, together with the improvement in structural properties, validates the potential of these materials in terms of applications in cost-effective and tunable solutions.

  9. On the new modes of planetary-scale electromagnetic waves in the ionosphere

    Directory of Open Access Journals (Sweden)

    G. D. Aburjania

    2004-04-01

    Full Text Available Using an analogy method the frequencies of new modes of the electromagnetic planetary-scale waves (with a wavelength of 103 km or more, having a weather forming nature, are found at different ionospheric altitudes. This method gives the possibility to determine spectra of ionospheric electromagnetic perturbations directly from the dynamic equations without solving the general dispersion equation. It is shown that the permanently acting factor-latitude variation of the geomagnetic field generates fast and slow weakly damping planetary electromagnetic waves in both the E- and F-layers of the ionosphere. The waves propagate eastward and westward along the parallels. The fast waves have phase velocities (1–5km s–1 and frequencies (10–1–10–4, and the slow waves propagate with velocities of the local winds with frequencies (10–4–10–6s–1 and are generated in the E-region of the ionosphere. Fast waves having phase velocities (10-1500km s–1 and frequencies (1–10–3s–1 are generated in the F-region of the ionosphere. The waves generate the geomagnetic pulsations of the order of one hundred nanoTesla by magnitude. The properties and parameters of the theoretically studied electromagnetic waves agree with those of large-scale ultra-low frequency perturbations observed experimentally in the ionosphere.

    Key words. Ionosphere (ionospheric disturbances; waves propagation; ionosphere atmosphere interactions

  10. Bending, splitting, compressing and expanding of electromagnetic waves in infinitely anisotropic media

    Science.gov (United States)

    Zhang, Youming; Zhang, Baile

    2018-01-01

    High-efficiency diffraction-free manipulations of electromagnetic (EM) waves are fundamentally difficult to realize, though reflectionless wave bending or sub-diffraction-limited imaging has been realized separately in previous demonstrations. Recent advances in epsilon-near-zero and anisotropic epsilon-near-infinity metamaterials have provided unique possibilities to achieve reflectionless diffraction-free EM wave manipulations. Here, we propose bending, splitting, compressing and expanding of EM waves with infinitely anisotropic media that can be achieved without diffraction or reflection. The results are verified by numerical simulations. This work furthers the study of infinitely anisotropic media, and might find applications in high-efficiency interconnection of subwavelength photonic information.

  11. Solving the characteristic initial-value problem for colliding plane gravitational and electromagnetic waves.

    Science.gov (United States)

    Alekseev, G A; Griffiths, J B

    2001-11-26

    A method is presented for solving the characteristic initial-value problem for the collision and subsequent nonlinear interaction of plane gravitational or gravitational and electromagnetic waves in a Minkowski background. This method generalizes the monodromy-transform approach to fields with nonanalytic behavior on the characteristics inherent to waves with distinct wave fronts. The crux of the method is in a reformulation of the main nonlinear symmetry reduced field equations as linear integral equations whose solutions are determined by generalized ("dynamical") monodromy data which evolve from data specified on the initial characteristics (the wave fronts).

  12. Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-03-15

    Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

  13. The interaction of a circularly orbiting electromagnetic harmonic wave with an electron having a constant time independent drift velocity

    NARCIS (Netherlands)

    Rashid, M.

    2011-01-01

    A circularly orbiting electromagnetic harmonic wave may appear when a 1S electron encounters a decelerating stopping positively charged hole inside a semiconductor. The circularly orbiting electromagnetic harmonic wave can have an interaction with a conducting electron which has a constant time

  14. Electromagnetic waves reflection, transmission and absorption by graphene - magnetic semiconductor - graphene sandwich-structure in magnetic field: Faraday geometry

    OpenAIRE

    Kuzmin, Dmitry A.; Bychkov, Igor V.; Shavrov, Vladimir G.

    2014-01-01

    Electrodynamic properties of the graphene - magnetic semiconductor - graphene sandwich-structure have been investigated theoretically with taking into account the dissipation processes. Influence of graphene layers on electromagnetic waves propagation in graphene - semi-infinte magnetic semiconductor and graphene - magnetic semiconductor - graphene sandwich-structure has been analyzed. Frequency and field dependences of the reflectance, transmittance and absorbtance of electromagnetic waves b...

  15. Propagation of electromagnetic waves parallel to the magnetic field in the nightside Venus ionosphere

    Science.gov (United States)

    Huba, J. D.; Rowland, H. L.

    1993-01-01

    The propagation of electromagnetic waves parallel to the magnetic field in the nightside Venus ionosphere is presented in a theoretical and numerical analysis. The model assumes a source of electromagnetic radiation in the Venus atmosphere, such as that produced by lightning. Specifically addressed is wave propagation in the altitude range z = 130-160 km at the four frequencies detectable by the Pioneer Venus Orbiter Electric Field Detector: 100 Hz, 730 Hz, 5.4 kHz, and 30 kHz. Parameterizations of the wave intensities, peak electron density, and Poynting flux as a function of magnetic field are presented. The waves are found to propagate most easily in conditions of low electron density and high magnetic field. The results of the model are consistent with observational data.

  16. Competition between atomic coherence and electromagnetically induced population grating in multi-wave mixing

    Science.gov (United States)

    Lou, Lin; Sun, Jia; Feng, Weikang; Wu, Zhenkun; Zhang, Yiqi; Zhang, Yanpeng

    2014-12-01

    We study the competition and transfer between atomic coherence and electromagnetically induced population grating of multi-wave mixing (MWM) in four- and five-level atomic systems. The MWM signal falls into a new type electromagnetically induced transparency (EIT) window that depends on propagating directions of the related fields rather than atomic system configuration. By blocking different coupling laser beams, we experimentally distinguish different wave mixing processes. In addition, by changing the detuning of pump beams, we can observe double peaks for both EIT and MWM signals. The results may have potential applications in correlated photon-pair generations in four-wave mixing as well as six-wave mixing and quantum information processing.

  17. Generation of large scale field-aligned density irregularities in ionospheric heating experiments. [electromagnetic wave decay

    Science.gov (United States)

    Fejer, J. A.

    1974-01-01

    Threshold and growth rate for stimulated Brillouin scattering are calculated for a uniform magnetoplasma. These are then compared with the threshold and growth rate of a new thermal instability in which the nonlinear Lorentz force felt by the electrons at the beat frequency of the two electromagnetic waves is replaced by a pressure force due to differential heating in the interference pattern of the pump wave and the generated electromagnetic wave. This thermal instability, which is still essentially stimulated Brillouin scattering, has a threshold which is especially low when the propagation vector of the beat wave is almost normal to the magnetic field. The threshold is then considerably lower than the threshold for normal stimulated Brillouin scattering and therefore this new instability is probably responsible for the generation of large scale field aligned irregularities and ionospheric spread F.

  18. Optical theorem for electromagnetic field scattering by dielectric structures and energy emission from the evanescent wave.

    Science.gov (United States)

    Gulyaev, Yu V; Barabanenkov, Yu N; Barabanenkov, M Yu; Nikitov, S A

    2005-08-01

    We present an optical theorem for evanescent (near field) electromagnetic wave scattering by a dielectric structure. The derivation is based on the formalism of angular spectrum wave amplitudes and block scattering matrix. The optical theorem shows that an energy flux is emitted in the direction of the evanescent wave decay upon scattering. The energy emission effect from an evanescent wave is illustrated in two examples of evanescent wave scattering, first, by the electrical dipole and, second, one-dimensional grating with line-like rulings. Within the latter example, we show that an emitted energy flux upon evanescent wave scattering can travel through a dielectric structure even if the structure has a forbidden gap in the transmission spectrum of incident propagating waves.

  19. The oblique behavior of low-frequency electromagnetic waves excited by newborn cometary ions

    Science.gov (United States)

    Brinca, Armando L.; Tsurutani, Bruce T.

    1989-01-01

    The free energy in oxygen or hydrogen ions freshly created in the solar wind stimulates low-frequency electromagnetic waves whose growth does not always maximize at parallel propagation. Exploration of the wave vector plane discloses the frequent occurrence of islets of oblique growth unconnected to the unstable parallel modes. Contour plots of the growth rate, real frequency, polarization, and magnetic compression characterize the oblique wave behavior for large values of the initial pitch angle of the cometary particles. Although wave-particle (Landau and cyclotron) resonances feed most of the surveyed oblique instabilities, some are seemingly fluidlike. The results, obtained from the numerical solution of the kinetic dispersion and wave equations, imply that newborn ions can easily excite significant oblique hydromagnetic wave activity. Cometary environments provide the adopted plasma model, but the study is helpful in the interpretation of other low-frequency wave observations in space.

  20. Scattering and polarization conversion of electromagnetic waves obliquely incident on a magnetized plasma layer

    Science.gov (United States)

    Cho, Suwon

    2017-07-01

    This paper addresses the scattering of electromagnetic waves obliquely incident on a magnetized plasma layer. It is shown that the polarizations of the waves can be converted when they are obliquely incident on a magnetized plasma layer. The scattering coefficients of the incident and converted waves are computed based on the analytic solutions of a uniform magnetized plasma slab. The total transmittance and reflectance are similar to those of the normal incidence, but the individual scattering coefficients of the incident and converted waves vary, depending on the dispersion characteristics of the ordinary and extraordinary modes in the plasma. The contributions of the converted wave increase with the wave number parallel to the magnetic field but decrease as the frequency increases above the upper hybrid resonance, regardless of the parallel wave number.

  1. Transient Electromagnetic Wave Propagation in a Plasma Waveguide

    Science.gov (United States)

    2011-10-24

    T. Van Duzer , Fields and Waves in Communication Electronics, 3rd edition, John Wiley & Sons, New York, NY, pp 395-455 (1994). 15. G.F. Miner, Lines...Whinnery, & T. Van Duzer , Fields and Waves in Communication Electronics, 1st edition, John Wiley & Sons, New York, NY, pp 432-434 (1965). 18. Ibid. p

  2. A novel protocol to measure the attenuation of electromagnetic waves through smoke

    Science.gov (United States)

    Yan-wu, Li; Hong-yong, Yuan; Yang, Lu; Xiaoxiang, Zhang; Ru-feng, Xu; Ming, Fu

    2016-06-01

    The electromagnetic properties of smoke from a structure fire are important in terms of their relation to the stability of wireless communication systems used in fire rescue. As it is hard to make a measurable electromagnetic environment for particles in the air, compressed and bulk samples are used instead to measure sand storms and smoke plumes. In this paper, an experiment system was designed to measure smoke particles in the air, in consideration of both smoke control and electromagnetic measurement. Several measures had been taken to create a fulfilled smoke environment. The simulated and measured transmission parameters of the electromagnetic testing area were approximate and the electromagnetic wave frequencies were set from 350 to 400 MHz. Repeated experiments have been conducted to test the stability of the results and they showed that there was no obvious attenuation until the smoke concentration was more than 10 dB m-1. It was found that the frequency around 355 and 360 MHz had a larger attenuation coefficient. The relationship between the attenuation coefficient and the smoke concentration was concluded to be linear. The results may help us understand the attenuation of electromagnetic waves within a smoke column.

  3. Scattering-induced changes in the degree of polarization of a stochastic electromagnetic plane-wave pulse.

    Science.gov (United States)

    Ding, Chaoliang; Cai, Yangjian; Zhang, Yongtao; Pan, Liuzhan

    2012-06-01

    The scattering of a stochastic electromagnetic plane-wave pulse on a deterministic spherical medium is investigated. An analytical formula for the degree of polarization (DOP) of the scattered field in the far zone is derived. Letting pulse duration T(0) → ∞, our formula can be applied to study the scattering of a stationary stochastic electromagnetic light wave. Numerical results show that the DOP of the far zone field is closely determined by the size of the spherical medium when the incident field is a stochastic electromagnetic plane-wave pulse. This is much different from the case when the incident field is a stationary stochastic electromagnetic light wave, where the DOP of the far zone field is independent of the size of the medium. One may obtain the information of the spherical medium by measuring the scattering-induced changes in the DOP of a stochastic electromagnetic plane-wave pulse.

  4. Preparation and characterization of TiO2 coated Fe nanofibers for electromagnetic wave absorber.

    Science.gov (United States)

    Jang, Dae-Hwan; Song, Hanbok; Lee, Young-In; Lee, Kun-Jae; Kim, Ki Hyeon; Oh, Sung-Tag; Lee, Sang-Kwan; Choa, Yong-Ho

    2011-01-01

    Recently, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) have become serious problems due to the growth of electronic device and next generation telecommunication. It is necessary to develop new electromagnetic wave absorbing material to overcome the limitation of electromagnetic wave shielding materials. The EMI attenuation is normally related to magnetic loss and dielectric loss. Therefore, magnetic material coating dielectric materials are required in this reason. In this study, TiO2 coated Fe nanofibers were prepared to improve their properties for electromagnetic wave absorption. Poly(vinylpyrrolidone) (PVP) and Iron (III) nitrate nonahydrate (Fe(NO3)3 x 9H2O) were used as starting materials for the synthesis of Fe oxide nanofibers. Fe oxide nanofibers were prepared by electrospinning in an electric field and heat treatment. TiO2 layer was coated on the surface of Fe oxide nanofibers using sol-gel process. After the reduction of TiO2 coated Fe oxide nanofibers, Fe nanofibers with a TiO2 coating layer of about 10 nm were successfully obtained. The morphology and structure of fibers were characterized by SEM, TEM, and XRD. In addition, the absorption properties of TiO2 coated Fe nanofibers were measured by network analyzer.

  5. Geometric Phase Of The Faraday Rotation Of Electromagnetic Waves In Magnetized Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jian Liu and Hong Qin

    2011-11-07

    The geometric phase of circularly polarized electromagnetic waves in nonuniform magnetized plasmas is studied theoretically. The variation of the propagation direction of circularly polarized waves results in a geometric phase, which also contributes to the Faraday rotation, in addition to the standard dynamical phase. The origin and properties of the geometric phase is investigated. The in uence of the geometric phase to plasma diagnostics using Faraday rotation is also discussed as an application of the theory.

  6. Electromagnetic Wave Propagation In The Plasma Layer of A Reentry Vehicle

    OpenAIRE

    Kundrapu, Madhusudhan; Loverich, John; Beckwith, Kris; Stoltz, Peter; Shashurin, Alexey; Keidar, Michael

    2014-01-01

    The ability to simulate a reentry vehicle plasma layer and the radio wave interaction with that layer, is crucial to the design of aerospace vehicles when the analysis of radio communication blackout is required. Results of aerothermal heating, plasma generation and electromagnetic wave propagation over a reentry vehicle are presented in this paper. Simulation of a magnetic window radio communication blackout mitigation method is successfully demonstrated.

  7. Electromagnetic time reversal focusing of near field waves in metamaterials

    Science.gov (United States)

    Chabalko, Matthew J.; Sample, Alanson P.

    2016-12-01

    Precise control of electromagnetic energy on a deeply subwavelength scale in the near field regime is a fundamentally challenging problem. In this letter we demonstrate the selective focusing of electromagnetic energy via the electromagnetic time reversal in the near field of a metamaterial. Our analysis begins with fundamental mathematics, and then is extended to the experimental realm where focusing in space and time of the magnetic fields in the near field of a 1-Dimensional metamaterial is shown. Under time reversal focusing, peak instantaneous fields at receiver locations are at minimum ˜200% greater than other receivers. We then leverage the strong selective focusing capabilities of the system to show individual and selective powering of light emitting diodes connected to coil receivers placed in the near field of the metamaterial. Our results show the possibility of improving display technologies, near field imaging systems, increasing channel capacity of near field communication systems, and obtaining a greater control of energy delivery in wireless power transfer systems.

  8. Electromagnetic properties of carbon black and barium titanate composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guiqin [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)], E-mail: c2b2chen@163.com; Chen Xiaodong; Duan Yuping; Liu Shunhua [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)

    2008-04-24

    Nanocrystalline carbon black/barium titanate compound particle (CP) was synthesized by sol-gel method. The phase structure and morphology of compound particle were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM) and Raman spectrum measurements, the electroconductivity was test by trielectrode arrangement and the precursor powder was followed by differential scanning calorimetric measurements (DSC) and thermal gravimetric analysis (TGA). In addition, the complex relative permittivity and permeability of compound particle were investigated by reflection method. The compound particle/epoxide resin composite (CP/EP) with different contents of CP were measured. The results show barium titanate crystal is tetragonal phase and its grain is oval shape with 80-100 nm which was coated by carbon black film. As electromagnetic (EM) complex permittivity, permeability and reflection loss (RL) shown that the compound particle is mainly a kind of electric and dielectric lossy materials and exhibits excellent microwave absorption performance in the X- and Ku-bands.

  9. Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

    Directory of Open Access Journals (Sweden)

    Vojkan M. Radonjić

    2011-01-01

    Full Text Available Quality transmission of digital signals from a transmitting radio-relay device to a receiving one depends on the impact of environmental effects on the propagation of electromagnetic waves. In this paper some of the most important effects are explained and modeled, especially those characteristic for the frequency range within which the GRC 408E operates. The modeling resulted in the conclusions about the quality of transmission of digital signals in the GRC 408E radio-relay equipment. Propagation of electromagnetic waves A radio-relay link is achieved by direct electromagnetic waves, provided there is a line of sight between the transmitting and receiving antenna of a radio-relay device. Electromagnetic waves on the road are exposed to various environmental influences causing phenomena such as bending, reflection, refraction, absorption and multiple propagation. Due to these environmental effects, the quality of information transmission is not satisfactory and a radio-relay link is not reliable. The approach to the analysis of the quality of links in digital radiorelay devices is different from the one in analog radio-relay devices. Therefore, the quality is seen through errors in the received bit ( BER , the propagation conditions are taken into account, a reservation for the fading is determined by other means, etc.. Phenomena which accompany the propagation of electromagnetic waves in digital radio-relay links The propagation of direct EM waves is followed by the following phenomena: - attenuation due to propagation, - diffraction (changing table, - refraction (refraction, - reflection (refusing, - absorption (absorption and - multiple wave propagation. Each of these has a negative effect on the quality of the received signal at the receiving antenna of the radio-relay device. Attenuation due to propagation of electromagnetic waves The main parameter for evaluating the quality of radio-relay links is the level of the field at the reception

  10. Measurement of the environmental broadband electromagnetic waves in a mid-size European city.

    Science.gov (United States)

    Fernández-García, R; Gil, I

    2017-10-01

    In this paper, the level of exposure to broadband radiofrequency electromagnetic field in a mid-size European city was evaluated in accordance with the International Commission on Non-ionizing Radiation Protection guidelines from 1998. With the aim to analyse all the potential electromagnetic waves present in the city up to 18GHz, a total of 271 locations distributed along Terrassa (Spain) have been measured. To show the results in an easy-to-interpret way by the citizen, the results have been represented in a set of raster maps. The measurement results obtained showed that the electromagnetic wave measured in all broadband frequency range along the city is much lower than the safety level according to the international regulations for both public and occupational sectors. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Nonorthogonality and κ-Dependence Eccentricity of Polarized Electromagnetic Waves in CPT-Even Lorentz Violation

    Directory of Open Access Journals (Sweden)

    Thiago Prudêncio

    2017-01-01

    Full Text Available We discuss the modified Maxwell action of a KF-type Lorentz symmetry breaking theory and present a solution of Maxwell equations derived in the cases of linear and elliptically polarized electromagnetic waves in the vacuum of CPT-even Lorentz violation. We show in this case that the Lorentz violation has the effect of changing the amplitude of one component of the magnetic field, while leaving the electric field unchanged, leading to nonorthogonal propagation of electromagnetic fields and dependence of the eccentricity on κ-term. Further, we exhibit numerically the consequences of this effect in the cases of linear and elliptical polarization, in particular, the regimes of nonorthogonality of the electromagnetic wave fields and the eccentricity of the elliptical polarization of the magnetic field with dependence on the κ-term.

  12. Millimeter Wave Holographical Inspection of Honeycomb Composites

    Science.gov (United States)

    Case, J. T.; Kharkovsky, S.; Zoughi, R.; Stefes, G.; Hepburn, Frank L.; Hepburn, Frank L.

    2007-01-01

    Multi-layered composite structures manufactured with honeycomb, foam or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as disbond, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz - 300 GHz with corresponding wavelengths of 10 - 1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

  13. Millimeter Wave Holographical Inspection of Honeycomb Composites

    Science.gov (United States)

    Case, J. T.; Kharkovsky, S.; Zoughi, R.; Steffes, G.; Hepburn, F. L.

    2008-02-01

    Multi-layered composite structures manufactured with honeycomb, foam, or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites, standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as isband, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz-300 GHz with corresponding wavelengths of 10-1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

  14. Acoustical Wave Propagation in Sonic Composites

    Directory of Open Access Journals (Sweden)

    Iulian Girip

    2015-09-01

    Full Text Available The goal of this paper is to discuss the technique of controlling the mechanical properties of sonic composites. The idea is to architecture the scatterers and material from which they are made, their number and geometry in order to obtain special features in their response to external waves. We refer to perfectly reflecting of acoustical waves over a desired range of frequencies or to prohibit their propagation in certain directions, or confining the waves within specified volumes. The internal structure of the material has to be chosen in such a way that to avoid the scattering of acoustical waves inside the material. This is possible if certain band-gaps of frequencies can be generated for which the waves are forbidden to propagate in certain directions. These bandgaps can be extended to cover all possible directions of propagation by resulting a full band-gap. If the band-gaps are not wide enough, their frequency ranges do not overlap. These band-gaps can overlap due to reflections on the surface of thick scatterers, as well as due to wave propagation inside them. growth.

  15. Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

    NARCIS (Netherlands)

    Abadie, J.; et al., [Unknown; Homan, J.; Fender, R.; Stappers, B.W.; Swinbank, J.; Wijers, R.A.M.J.

    2012-01-01

    Aims: A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in

  16. Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

    NARCIS (Netherlands)

    Abadie, J.; van den Brand, J.F.J.; Bulten, H.J.; Rabeling, D.S.

    2012-01-01

    Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in

  17. Scattering of electromagnetic waves by charged spheres: near-field external intensity distribution.

    Science.gov (United States)

    Kocifaj, Miroslav; Klačka, Jozef

    2012-01-15

    This Letter treats the scattering of electromagnetic waves by an electrically charged spherical particle in near-field approximation. Particular attention is paid to the external intensity distribution at the outer edges of the particle. The difference between scattering by a charged sphere and an electrically neutral sphere is significant only when size parameters exceed unity.

  18. Near field computation of the extinction of electromagnetic waves in multiparticle systems

    Directory of Open Access Journals (Sweden)

    J. Schaefer

    2011-09-01

    Full Text Available In this contribution extinction of electromagnetic waves inside a medium consisting of cylindrical absorbing particles is considered. Near fields are calculated using a numerical solution of Maxwell’s equations and compared to results given by Lambert- Beer’s law.

  19. Low-frequency electromagnetic plasma waves at comet P/Grigg-Skjellerup: Analysis and interpretation

    Science.gov (United States)

    Neubauer, Fritz M.; Glassmeier, Karl-Heinz; Coates, A. J.; Johnstone, A. D.

    1993-01-01

    The propagation and polarization characteristic of low-frequency electromagnetic wave fields near comet P/Grigg-Skjellerup (P/GS) are analyzed using magnetic field and plasma observations obtained by the Giotto magnetometer experiment and the Johnstone plasma analyzer during the encounter at the comet on July 10, 1992. The results have been physically interpreted.

  20. Student Understanding of Light as an Electromagnetic Wave: Relating the Formalism to Physical Phenomena.

    Science.gov (United States)

    Ambrose, Bradley S.; Heron, Paula R. L.; Vokos, Stamatis; McDermott, Lillian C.

    1999-01-01

    Some serious difficulties that students have in understanding physical optics may be due in part to a lack of understanding of light as an electromagnetic wave. Describes the development and use of tutorials designed to address students' conceptual difficulties. (Contains over 15 references.) (Author/WRM)

  1. Transversality of Electromagnetic Waves in the Calculus-Based Introductory Physics Course

    Science.gov (United States)

    Burko, Lior M.

    2008-01-01

    Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by…

  2. Modelling Scattering of Electromagnetic Waves in Layered Media: An Up-to-Date Perspective

    Directory of Open Access Journals (Sweden)

    Pasquale Imperatore

    2017-01-01

    Full Text Available This paper addresses the subject of electromagnetic wave scattering in layered media, thus covering the recent progress achieved with different approaches. Existing theories and models are analyzed, classified, and summarized on the basis of their characteristics. Emphasis is placed on both theoretical and practical application. Finally, patterns and trends in the current literature are identified and critically discussed.

  3. NUMERICAL STUDY OF ELECTROMAGNETIC WAVES GENERATED BY A PROTOTYPE DIELECTRIC LOGGING TOOL

    Science.gov (United States)

    To understand the electromagnetic waves generated by a prototype dielectric logging tool, a numerical study was conducted using both the finite-difference, time-domain method and a frequency- wavenumber method. When the propagation velocity in the borehole was greater than th...

  4. Electromagnetically-induced phase grating: a coupled-wave theory analysis.

    Science.gov (United States)

    de Carvalho, Silvânia A; de Araujo, Luis E E

    2011-01-31

    We use a coupled-wave theory analysis to describe an atomic phase grating based on the giant Kerr nonlinearity of an atomic medium under electromagnetically induced transparency. An analytical expression is found for the diffraction efficiency of the grating. Efficiencies greater than 70% are predicted for incidence at the Bragg angle.

  5. Assessment methodology of counter-personnel high power electromagnetic millimeter wave effects

    NARCIS (Netherlands)

    Valente, F.; Horst, M.J. van der; Paulissen, J.J.M.; Zwamborn, A.P.M.; Toet, A.

    2013-01-01

    The group of NLW that arguably offers the largest amount of useful applications are based on high power electromagnetic millimetre wave technology. This group is often referred to as ‘Active Denial Systems’ (ADS), since they are primarily aimed at deterring and dispersing people out of an area. The

  6. Biological effects of THz electromagnetic waves on frequencies of active cell metabolites at a molecular level

    OpenAIRE

    Vyacheslav F. Kirichuk; Alexander A. Tsymbal

    2013-01-01

    A reaction of biomolecules had been studied, including an effect of albumin molecules on THz electromagnetic waves on frequencies of active cell metabolites (nitrogen oxide 150.176-150.664 GHz and atmospheric oxygen 129.0 GHz). Change of conformational molecule state had been displayed.

  7. Electromagnetic smog - a hazard; Environmental effects of electromagnetic waves. Gefaehrdung durch Elektrosmog; Elektromagnetische Wellen und Umwelt

    Energy Technology Data Exchange (ETDEWEB)

    Rosette, C.

    1993-06-01

    The author discusses a conceivable correlation between the new types of forest injuries and electromagnetic smog and a correlation in circulatory, cancer and rheumatic diseases in man. Magnetic particles recently discovered in the human brain are suggested to function as aerials. The author demands that it should be biologists and physicians rather than engineers and technologists who are to rate plants and systems for their general recognition as being safe. (MG)

  8. Electromagnetic cyclotron waves near the proton cyclotron frequency in the solar wind

    Science.gov (United States)

    Jian, Lan K.; Boardsen, Scott; Moya, Pablo; Stevens, Michael; Alexander, Robert; Vinas, Adolfo

    2015-04-01

    Strong narrow-band electromagnetic waves around the proton cyclotron frequency (fpc) have been found sporadically in the solar wind from 0.3 to 0.7 AU during MESSENGER spacecraft’s cruise phase. These waves are transverse and circularly polarized, and they propagate in directions quasi-parallel to the magnetic field. The wave power decreases quadratically with heliocentric distance, faster than the trend if assuming the conservation of Poynting flux for wave packets, suggesting there is energy dissipation from the waves, which could contribute to the heating and acceleration of solar wind plasma. Although the wave frequency is a few times of fpc in the spacecraft frame, it is a fraction of fpc in the solar wind plasma frame after removing the Doppler shift effect. In this frequency range, the waves can be left-hand (LH) polarized ion cyclotron waves or right-hand (RH) polarized magnetosonic waves. Because the waves are LH or RH polarized in the spacecraft frame with otherwise nearly identical characteristics, they could be due to Doppler shift of a same type of waves or a mixture of waves with intrinsically different polarizations. Through the assistance of audification, we have studied the long-lasting wave events in 2005 using high-cadence magnetic field data from the Wind mission. Statistically, in contrast with general solar wind, the protons at these waves are distributed closer to the proton instability thresholds, while the alpha particles at these waves are distributed further away from the alpha instability thresholds. For selected events of extensive waves, the ion distribution is analyzed in detail. A mixture of temperature anisotropies for core protons, beam protons, and alpha particles, as well as proton beam drift are often found in such events. We conduct linear wave dispersion analysis using these ion moments to examine whether these waves can be explained by the local generation of kinetic instabilities such as the LH ion cyclotron, the RH

  9. Spawns Structure of Rod-Like ZnO Wrapped in Cellulose Nanofibers for Electromagnetic Wave Absorption

    Directory of Open Access Journals (Sweden)

    Bitao Fan

    2017-01-01

    Full Text Available Spawns structure of rod-like ZnO wrapped in the cellulose nanofibers was successfully fabricated through a facile one-step hydrothermal method, and their electromagnetic wave absorption properties were investigated. The structure and properties of the composite aerogel were characterized. The enlarged morphology images showed that the as-prepared cellulose nanofiber/ZnO samples were spawns structure of rod-like ZnO wrapped in the cellulose nanofibers. The composite aerogel in a wax matrix exhibited excellent electromagnetic wave absorption performance over 2–18 GHz. The widest absorption bandwidth of 30 wt% contained with reflection loss values less than −10 dB was up to 12 GHz (6–18 GHz at the thickness of 5.5 mm and the minimum reflection loss value reached −26.32 dB at 15.2 GHz when the thickness of the absorber was 3 mm.

  10. Spectrum of the seismic-electromagnetic and acoustic waves caused by seismic and volcano activity

    Directory of Open Access Journals (Sweden)

    S. Koshevaya

    2005-01-01

    Full Text Available Modeling of the spectrum of the seismo-electromagnetic and acoustic waves, caused by seismic and volcanic activity, has been done. This spectrum includes the Electromagnetic Emission (EME, due to fracturing piezoelectrics in rocks and the Acoustic Emission (AE, caused by the excitation and the nonlinear passage of acoustic waves through the Earth's crust, the atmosphere, and the ionosphere. The investigated mechanism of the EME uses the model of fracturing and the crack motion. For its analysis, we consider a piezoelectric crystal under mechanical stresses, which cause the uniform crack motion, and, consequently, in the vicinity of the moving crack also cause non-stationary polarization currents. A possible spectrum of EME has been estimated. The underground fractures produce Very Low (VLF and Extremely Low Frequency (ELF acoustic waves, while the acoustic waves at higher frequencies present high losses and, on the Earth's surface, they are quite small and are not registered. The VLF acoustic wave is subject to nonlinearity under passage through the lithosphere that leads to the generation of higher harmonics and also frequency down-conversion, namely, increasing the ELF acoustic component on the Earth's surface. In turn, a nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to emerging the ultra low frequency (ULF acousto-gravity waves in the ionosphere and possible local excitation of plasma waves.

  11. Transduction of DNA information through water and electromagnetic waves.

    Science.gov (United States)

    Montagnier, Luc; Del Giudice, Emilio; Aïssa, Jamal; Lavallee, Claude; Motschwiller, Steven; Capolupo, Antonio; Polcari, Albino; Romano, Paola; Tedeschi, Alberto; Vitiello, Giuseppe

    2015-01-01

    The experimental conditions by which electromagnetic signals (EMS) of low frequency can be emitted by diluted aqueous solutions of some bacterial and viral DNAs are described. That the recorded EMS and nanostructures induced in water carry the DNA information (sequence) is shown by retrieval of that same DNA by classical PCR amplification using the TAQ polymerase, including both primers and nucleotides. Moreover, such a transduction process has also been observed in living human cells exposed to EMS irradiation. These experiments suggest that coherent long-range molecular interaction must be present in water to observe the above-mentioned features. The quantum field theory analysis of the phenomenon is presented in this article.

  12. Hanbury Brown-Twiss effect with electromagnetic waves.

    Science.gov (United States)

    Hassinen, T; Tervo, J; Setälä, T; Friberg, A T

    2011-08-01

    The classic Hanbury Brown-Twiss experiment is analyzed in the space-frequency domain by taking into account the vectorial nature of the radiation. We show that as in scalar theory, the degree of electromagnetic coherence fully characterizes the fluctuations of the photoelectron currents when a random vector field with Gaussian statistics is incident onto the detectors. Interpretation of this result in terms of the modulations of optical intensity and polarization state in two-beam interference is discussed. We demonstrate that the degree of cross-polarization may generally diverge. We also evaluate the effects of the state of polarization on the correlations of intensity fluctuations in various circumstances.

  13. Modal Ring Method for the Scattering of Electromagnetic Waves

    Science.gov (United States)

    Baumeister, Kenneth J.; Kreider, Kevin L.

    1993-01-01

    The modal ring method for electromagnetic scattering from perfectly electric conducting (PEC) symmetrical bodies is presented. The scattering body is represented by a line of finite elements (triangular) on its outer surface. The infinite computational region surrounding the body is represented analytically by an eigenfunction expansion. The modal ring method effectively reduces the two dimensional scattering problem to a one-dimensional problem similar to the method of moments. The modal element method is capable of handling very high frequency scattering because it has a highly banded solution matrix.

  14. Self-Consistent Ring Current/Electromagnetic Ion Cyclotron Waves Modeling

    Science.gov (United States)

    Khazanov, G. V.; Gamayunov, K.; Gallagher, D.

    2006-12-01

    The self-consistent treatment of ring current (RC) ion dynamics and electromagnetic ion cyclotron (EMIC) waves, which are thought to exert important influences on dynamic ion evolution and are an important missing element in our understanding of the storm-and recovery-time ring current evolution. For example, the EMIC waves cause the RC decay on a time scale of about one hour or less during the main phase of storms. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Under certain conditions, relativistic electrons, with energies ~1 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is a critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMIC waves in global dynamic modeling of self-consistent RC - EMIC waves coupling. The results of our newly developed model will be presented, focusing mainly on the dynamics of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We will also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

  15. Enhanced electromagnetic interference shielding properties of carbon fiber veil/Fe3O4 nanoparticles/epoxy multiscale composites

    Science.gov (United States)

    Chen, Wei; Wang, Jun; Zhang, Bin; Wu, Qilei; Su, Xiaogang

    2017-12-01

    The multiscale approach has been adapted to enhance the electromagnetic interference shielding properties of carbon fiber (CF) veil epoxy-based composites. The Fe3O4 nanoparticles (NPs) were homogeneously dispersed in the epoxy matrix after surface modification by using silane coupling agent. The CF veil/Fe3O4 NPs/epoxy multiscale composites were manufactured by impregnating the CF veils with Fe3O4 NPs/epoxy mixture to prepare prepreg followed by vacuum bagging process. The electromagnetic interference shielding properties combined with the complex permittivity and complex permeability of the composites were investigated in the X-band (8.2–12.4 GHz) range. The total shielding effectiveness (SET) increases with increasing Fe3O4 NPs loadings and the maximum SET is 51.5 dB at low thickness of 1 mm. The incorporation of Fe3O4 NPs into the composites enhances the complex permittivity and complex permeability thus enhancing the electromagnetic wave absorption capability. The increased SET dominated by absorption loss SEA is attributed to the enhanced magnetic loss and dielectric loss generated by Fe3O4 NPs and multilayer construction of the composites. The microwave conductivity increases and the skin depth decreases with increasing Fe3O4 NPs loadings.

  16. Frequency Management for Electromagnetic Continuous Wave Conductivity Meters

    Directory of Open Access Journals (Sweden)

    Przemyslaw Mazurek

    2016-04-01

    Full Text Available Ground conductivity meters use electromagnetic fields for the mapping of geological variations, like the determination of water amount, depending on ground layers, which is important for the state analysis of embankments. The VLF band is contaminated by numerous natural and artificial electromagnetic interference signals. Prior to the determination of ground conductivity, the meter’s working frequency is not possible, due to the variable frequency of the interferences. Frequency management based on the analysis of the selected band using track-before-detect (TBD algorithms, which allows dynamical frequency changes of the conductivity of the meter transmitting part, is proposed in the paper. Naive maximum value search, spatio-temporal TBD (ST-TBD, Viterbi TBD and a new algorithm that uses combined ST-TBD and Viterbi TBD are compared. Monte Carlo tests are provided for the numerical analysis of the properties for a single interference signal in the considered band, and a new approach based on combined ST-TBD and Viterbi algorithms shows the best performance. The considered algorithms process spectrogram data for the selected band, so DFT (Discrete Fourier Transform could be applied for the computation of the spectrogram. Real–time properties, related to the latency, are discussed also, and it is shown that TBD algorithms are feasible for real applications.

  17. Coupled equations of electromagnetic waves in nonlinear metamaterial waveguides.

    Science.gov (United States)

    Azari, Mina; Hatami, Mohsen; Meygoli, Vahid; Yousefi, Elham

    2016-11-01

    Over the past decades, scientists have presented ways to manipulate the macroscopic properties of a material at levels unachieved before, and called them metamaterials. This research can be considered an important step forward in electromagnetics and optics. In this study, higher-order nonlinear coupled equations in a special kind of metamaterial waveguides (a planar waveguide with metamaterial core) will be derived from both electric and magnetic components of the transverse electric mode of electromagnetic pulse propagation. On the other hand, achieving the refractive index in this research is worthwhile. It is also shown that the coupled equations are not symmetric with respect to the electric and magnetic fields, unlike these kinds of equations in fiber optics and dielectric waveguides. Simulations on the propagation of a fundamental soliton pulse in a nonlinear metamaterial waveguide near the resonance frequency (a little lower than the magnetic resonant frequency) are performed to study its behavior. These pulses are recommended to practice in optical communications in controlled switching by external voltage, even in low power.

  18. Guided wave attenuation in composite materials

    Science.gov (United States)

    Wandowski, Tomasz; Kudela, Pawel; Malinowski, Pawel; Ostachowicz, Wieslaw

    2017-04-01

    In this paper problem of guided wave damping in composite materials is investigated. Material damping is estimated from experimental measurements based on energy of propagating guided waves. Simply Rayleigh damping is introduced into the model in the form of damping matrix proportional to the mass matrix. The numerical model is based on Spectral Element Method (SEM). Numerical model includes the piezoelectric transducer and bond layer between actuator and the host structure. In this paper each ply of composite laminate is simulated by separate layer consisting of 3D brick spectral elements. Numerical results are experimentally validated using Scanning Laser Doppler Vibrometry (SLDV). Guided waves are excited using piezoelectric transducer and registered using non-contact device - the laser vibrometer. Validation is based on signals gathered in dispersed points as well as on full wavefield measurements. The full wavefield measurements are conducted on dense grid of points. In this paper results for simple carbon fiber reinforced polymer are presented. Paper presents result for composite structure for damaged case. Investigated damage is in the form of delamination.

  19. Luminous phenomena and electromagnetic VHF wave emission originated from earthquake-related radon exhalation

    Science.gov (United States)

    Seki, A.; Tobo, I.; Omori, Y.; Muto, J.; Nagahama, H.

    2013-12-01

    Anomalous luminous phenomena and electromagnetic wave emission before or during earthquakes have been reported (e.g., the 1965 Matsushiro earthquake swarm). However, their mechanism is still unsolved, in spite of many models for these phenomena. Here, we propose a new model about luminous phenomena and electromagnetic wave emission during earthquake by focusing on atmospheric radon (Rn-222) and its daughter nuclides (Po-218 and Po-214). Rn-222, Po-218 and Po-214 are alpha emitters, and these alpha particles ionize atmospheric molecules. A light emission phenomenon, called 'the air luminescence', is caused by de-excitation of the ionized molecules of atmospheric nitrogen due to electron impact ionization from alpha particles. The de-excitation is from the second positive system of neutral nitrogen molecules and the first negative system of nitrogen molecule ion. Wavelengths of lights by these transitions include the visible light wavelength. So based on this mechanism, we proposed a new luminous phenomenon model before or during earthquake: 1. The concentration of atmospheric radon and its daughter nuclides increase anomalously before or during earthquakes, 2. Nitrogen molecules and their ions are excited by alpha particles emitted from Rn-222, Po-218 and Po-214, and air luminescence is generated by their de-excitation. Similarly, electromagnetic VHF wave emission can be explained by ionizing effect of radon and its daughter nuclides. Boyarchuk et al. (2005) proposed a model that electromagnetic VHF wave emission is originated when excited state of neutral clusters changes. Radon gas ionizes atmosphere and forms positively and negatively charged heavy particles. The process of ion hydration in ordinary air can be determined by the formation of complex chemically active structures of the various types of ion radicals. As a result of the association of such hydration radical ions, a neutral cluster, which is dipole quasi-molecules, is formed. A neutral cluster

  20. Theory of Nonlinear Guided Electromagnetic Waves in a Plane Two-Layered Dielectric Waveguide

    Directory of Open Access Journals (Sweden)

    Valeria Yu. Kurseeva

    2017-01-01

    Full Text Available Propagation of transverse electric electromagnetic waves in a homogeneous plane two-layered dielectric waveguide filled with a nonlinear medium is considered. The original wave propagation problem is reduced to a nonlinear eigenvalue problem for an equation with discontinuous coefficients. The eigenvalues are propagation constants (PCs of the guided waves that the waveguide supports. The existence of PCs that do not have linear counterparts and therefore cannot be found with any perturbation method is proven. PCs without linear counterparts correspond to a novel propagation regime that arises due to the nonlinearity. Numerical results are also presented; the comparison between linear and nonlinear cases is made.

  1. A broadband and omnidirectional electromagnetic wave concentrator with gradient woodpile structure.

    Science.gov (United States)

    Yin, Ming; Tian, Xiao Yong; Wu, Ling Ling; Li, Di Chen

    2013-08-12

    We present the first realized three-dimensional (3D) practical implementation of the so called "optical black hole" in microwave frequencies, an electromagnetic (EM) concentrator. The 3D EM wave concentrator was designed with non-resonant gradient index (GRIN) 3D woodpile photonic crystals (PCs) structure in metamaterial regime, and fabricated by Stereolithography (SL) process. Omnidirectional EM wave capture and absorbing ability of the device in a broad bandwidth (12GHz-15GHz) were validated by full-wave simulation and experiments. Such devices may have applications in microwave energy harvesting and radiation detector.

  2. The electromagnetic-trait imaging computation of traveling wave method in breast tumor microwave sensor system.

    Science.gov (United States)

    Tao, Zhi-Fu; Han, Zhong-Ling; Yao, Meng

    2011-01-01

    Using the difference of dielectric constant between malignant tumor tissue and normal breast tissue, breast tumor microwave sensor system (BRATUMASS) determines the detected target of imaging electromagnetic trait by analyzing the properties of target tissue back wave obtained after near-field microwave radicalization (conelrad). The key of obtained target properties relationship and reconstructed detected space is to analyze the characteristics of the whole process from microwave transmission to back wave reception. Using traveling wave method, we derive spatial transmission properties and the relationship of the relation detected points distances, and valuate the properties of each unit by statistical valuation theory. This chapter gives the experimental data analysis results.

  3. Theory and experiment on electromagnetic-wave-propagation velocities in stacked superconducting tunnel structures

    DEFF Research Database (Denmark)

    Sakai, S.; Ustinov, A. V.; Kohlstedt, H.

    1994-01-01

    focused on. Furthermore, under the assumption that all parameters of the layers are equal, analytic solutions for a generic N-fold stack are presented. The velocities of the waves in two- and three-junction stacks by Nb-Al-AlOx-Nb systems are experimentally obtained by measuring the cavity resonance......Characteristic velocities of the electromagnetic waves propagating in vertically stacked Josephson transmission are theoretically discussed. An equation for solving n velocities of the waves in an n Josephson-junction stack is derived. The solutions of two- and threefold stacks are especially...

  4. Transmission of electromagnetic waves through a two-layer plasma structure with spatially nonuniform electron density.

    Science.gov (United States)

    Denysenko, I B; Ivko, S; Smolyakov, A; Azarenkov, N A

    2012-11-01

    Transmission of a p-polarized electromagnetic wave through a two-layer plasma structure with spatially nonuniform distributions of electron density in the layers is studied. The case, when the electromagnetic wave is obliquely incident on the structure and is evanescent in both plasma layers, is considered. The conditions for total transparency of the two-layer structure are found for the thin slab case and when the plasma inhomogeneity is weak. It is shown that the transmission coefficient of the p-polarized wave can be about unity, even if the plasma inhomogeneity is large. The effects of plasma inhomogeneity on transparency of the structure are more important if the slabs are thick, comparing with the case of thin layers.

  5. Nonlinear electromagnetic formulation for particle simulation of lower hybrid waves in toroidal geometry

    CERN Document Server

    Bao, J; Kuley, A; Wang, Z X

    2016-01-01

    Electromagnetic particle simulation model has been formulated and verified for nonlinear processes of lower hybrid (LH) waves in fusion plasmas. Electron dynamics is described by the drift kinetic equation using either kinetic momentum or canonical momentum. Ion dynamics is treated as the fluid system or by the Vlasov equation. Compressible magnetic perturbation is retained to simulate both the fast and slow LH waves. Numerical properties are greatly improved by using electron continuity equation to enforce consistency between electrostatic potential and vector potential, and by using the importance sampling technique. The simulation model has been implemented in the gyrokinetic toroidal code (GTC), and verified for the dispersion relation and nonlinear particle trapping of the electromagnetic LH waves.

  6. Nonlinear longitudinal current, generated by two transversal electromagnetic waves in collisionless plasma

    CERN Document Server

    Latyshev, A V; Algazin, O D; Kopaev, A V; Popov, V S

    2015-01-01

    Classical plasma with any degree degeneration of electronic gas is considered. In plasma two external electromagnetic field are propagation. It is required to find the plasma response on these fields. From kinetic Vlasov equation for collisionless plasmas distribution function in square-law approximation on sizes of intensivities of two electric fields is received. The formula for calculation electric current at any temperature (any degree of degeneration electronic gas) is deduced. This formula contains an one-dimensional quadrature. It is shown, that the nonlinearity account leads to occurrence the longitudinal electric current directed along a wave vector. This longitudinal current is perpendicular to known tranversal classical current, received at the linear analysis. The case of small values of wave number is considered. Graphic comparison of dimensionless size of the current depending on wave number and frequency of oscillation of the electromagnetic fields is carry out.

  7. Resonant interactions between cometary ions and low frequency electromagnetic waves

    Science.gov (United States)

    Thorne, Richard M.; Tsurutani, Bruce T.

    1987-01-01

    The conditions for resonant wave amplification in a plasma with a ring-beam distribution which is intended to model pick-up ions in a cometary environment are investigated. The inclination between the interplanetary field and the solar wind is found to play a crucial role in governing both the resonant frequency and the growth rate of any unstable mode. It is suggested that the low-frequency MHD mode should experience the most rapid amplification for intermediate inclination. In the frame of the solar wind, such waves should propagate along the field in the direction upstream toward the sun with a phase speed lower than the beaming velocity of the pick-up ions. This mechanism may account for the presence of the interior MHD waves noted by satellites over a region surrounding comets Giacobini-Zinner and Halley.

  8. Flat metasurfaces to focus electromagnetic waves in reflection geometry.

    Science.gov (United States)

    Li, Xin; Xiao, Shiyi; Cai, Bengeng; He, Qiong; Cui, Tie Jun; Zhou, Lei

    2012-12-01

    We show that a flat metasurface with a parabolic reflection-phase distribution can focus an impinging plane wave to a point image in reflection geometry. Our system is much thinner than conventional geometric-optics devices and does not suffer the energy-loss issues encountered by many metamaterial devices working in transmission geometry. We designed realistic microwave samples and performed near-field scanning experiments to verify the focusing effect. Experimental results are in good agreement with full wave simulations, model calculations, and theoretical analyses.

  9. Preparation and electromagnetic wave absorption of RGO/Cu nanocomposite

    Science.gov (United States)

    Zhang, Hui; Tian, Xingyou; Zhang, Xian; Li, Shikuo; Shen, Yuhua; Xie, Anjian

    2017-09-01

    We use a facile pyrolysis method to prepare reduced graphene oxide and copper nanocomposite (RGO/Cu) based on it. The product shows an outstanding wave absorption properties. The maximum reflection loss is up to-50.7 dB at 3.8 GHz. The reflection loss of-10 dB (90% power absorption) corresponds to a bandwidth of 11.2 GHz (3.4-14.6 GHz range) for the layer thickness of 2-5 mm. Therefore, it is suggested that the RGO/Cu nanocomposite is also a new kind of lightweight and high-performance EM wave absorbing material.

  10. Ion Acceleration by the Radiation Pressure of Slow Electromagnetic Wave

    CERN Document Server

    Bulanov, S V; Kando, M; Pegoraro, F; Bulanov, S S; Geddes, C G R; Schroeder, C; Esarey, E; Leemans, W

    2012-01-01

    When the ions are accelerated by the radiation pressure of the laser pulse, their velocity can not exceed the laser group velocity, in the case when it is less than the speed of light in vacuum. This is demonstrated in two cases corresponding to the thin foil target irradiated by a high intensity laser light and to the hole boring by the laser pulse in the extended plasma accompanied by the collisionless shock wave formation. It is found that the beams of accelerated at the collisionless shock wave front ions are unstable against the Buneman-lke and the Weibel-like instabilities which result in the ion energy spectrum broadening.

  11. Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering.

    Science.gov (United States)

    Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian

    2016-10-24

    Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence.

  12. Non-invasive temperature measurement by using phase changes in electromagnetic waves in a cavity resonator.

    Science.gov (United States)

    Ishihara, Yasutoshi; Ohwada, Hiroshi

    2011-01-01

    To improve the efficacy of hyperthermia treatment, a novel method of non-invasive measurement of changes in body temperature is proposed. The proposed method is based on phase changes with temperature in electromagnetic waves in a heating applicator and the temperature dependence of the dielectric constant. An image of the temperature change inside a body is reconstructed by applying a computed tomography algorithm. This method can be combined easily with a heating applicator based on a cavity resonator and can be used to treat cancer effectively while non-invasively monitoring the heating effect. In this paper the phase change distributions of electromagnetic waves with temperature changes are measured experimentally, and the accuracy of reconstruction is discussed. The phase change distribution is reconstructed by using a prototype system with a rectangular aluminum cavity resonator that can be rotated 360° around an axis of rotation. To make measurements without disturbing the electromagnetic field distribution, an optical electric field sensor is used. The phase change distribution is reconstructed from 4-projection data by using a simple back-projection algorithm. The paper demonstrates that the phase change distribution can be reconstructed. The difference between phase changes obtained experimentally and by numerical analysis is about 20% and is related mainly to the limited signal detection sensitivity of electromagnetic waves. A temperature change inside an object can be reconstructed from the measured phase changes in a cavity resonator.

  13. Success of electromagnetic shock wave lithotripter as monotherapy ...

    African Journals Online (AJOL)

    K.S. Meitei

    Abstract. Objectives: To evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renal stones larger than 2 cm without ureteral stenting. Hence, if our study result demonstrates acceptable success and safety, we can recommend ESWL as a treatment option for patients with large renal calculi.

  14. Stimulated Brillouin scattering of an electromagnetic wave in weakly ...

    Indian Academy of Sciences (India)

    The importance of the laser–plasma interaction becomes an active field of research in the laser-fusion experiments, charged particle acceleration experiments, X-ray generation, propagation of EM waves in ionosphere etc. and the stimulated Bril- louin scattering (SBS) plays an important role in laser–plasma interaction as it.

  15. Electromagnetic wave propagation in rain and polarization effects

    Science.gov (United States)

    OKAMURA, Sogo; OGUCHI, Tomohiro

    2010-01-01

    This paper summarizes our study on microwave and millimeter-wave propagation in rain with special emphasis on the effects of polarization. Starting from a recount of our past findings, we will discuss developments with these and how they are connected with subsequent research. PMID:20551593

  16. On the effects of geometry on guided electromagnetic waves

    Directory of Open Access Journals (Sweden)

    Tucker Robin W.

    2007-01-01

    Full Text Available The method of moving (Cartan coframes is used to analyze the influence of geometry on the behavior of electromagnetic fields in confining guides and the effect of such fields on their ultra-relativistic sources. Such issues are of relevance to a number of topical problems in accelerator science where the need to control the motion of high current-density micro-meter size bunches of relativistic radiating charge remains a technical and theoretical challenge. By dimensionally reducing the exterior equations for the sources and fields on spacetime using symmetries exhibited by the confining guides one achieves a unifying view that offers natural perturbative approaches for dealing with smooth non-uniform and curved guides. The issue of the back-reaction of radiation fields on the sources is approached in terms of a simple charged relativistic fluid model. .

  17. Harvesting the Energy of Multi-Polarized Electromagnetic Waves.

    Science.gov (United States)

    Almoneef, Thamer S; Erkmen, Faruk; Ramahi, Omar M

    2017-11-07

    We present the idea and design of a dual polarized metasurface for electromagnetic energy harvesting. A 4 × 4 super cell with alternating vias between adjacent cells was designed to allow for capturing the energy from various incident angles at an operating frequency of 2.4 GHz. The collected energy is then channeled to a feeding network that collects the AC power and feeds it to a rectification circuitry. The simulation results yielded a radiation to AC and an AC to DC conversion efficiencies of around 90% and 80%, respectively. As a proof of concept, an array consisting of 9 super cells was fabricated and measured. The experimental results show that the proposed energy harvester is capable of capturing up to 70% of the energy from a planewave having various polarizations and converting it to usable DC power.

  18. Breathers in Josephson junction ladders: resonances and electromagnetic wave spectroscopy.

    Science.gov (United States)

    Miroshnichenko, A E; Flach, S; Fistul, M V; Zolotaryuk, Y; Page, J B

    2001-12-01

    We present a theoretical study of the resonant interaction between dynamical localized states (discrete breathers) and linear electromagnetic excitations (EE's) in Josephson junction ladders. By making use of direct numerical simulations we find that such an interaction manifests itself by resonant steps and various sharp switchings (voltage jumps) in the current-voltage characteristics. Moreover, the power of ac oscillations away from the breather center (the breather tail) displays singularities as the externally applied dc bias decreases. All these features may be mapped to the spectrum of EE's that has been derived analytically and numerically. Using an improved analysis of the breather tail, a spectroscopy of the EE's is developed. The nature of breather instability driven by localized EE's is established.

  19. Some consequences of intense electromagnetic wave injection into space plasmas

    Science.gov (United States)

    Burke, William J.; Rothwell, Paul L.; Rothwell, Paul L.; Rothwell, Paul L.

    1986-01-01

    The future possibility of actively testing the current understanding of how energetic particles may be accelerated in space or dumped from the radiation belts using intense electromagnetic energy from ground based antennas is discussed. The ground source of radiation is merely a convenience. A space station source for radiation that does not have to pass through the atmosphere and lower ionosphere, is an attractive alternative. The text is divided into two main sections addressing the possibilities of: (1) accelerating electrons to fill selected flux tubes above the Kennel-Petscheck limit for stably trapped fluxes, and (2) using an Alfven maser to cause rapid depletion of energetic protons or electrons from the radiation belts.

  20. Theory of a ring laser. [electromagnetic field and wave equations

    Science.gov (United States)

    Menegozzi, L. N.; Lamb, W. E., Jr.

    1973-01-01

    Development of a systematic formulation of the theory of a ring laser which is based on first principles and uses a well-known model for laser operation. A simple physical derivation of the electromagnetic field equations for a noninertial reference frame in uniform rotation is presented, and an attempt is made to clarify the nature of the Fox-Li modes for an open polygonal resonator. The polarization of the active medium is obtained by using a Fourier-series method which permits the formulation of a strong-signal theory, and solutions are given in terms of continued fractions. It is shown that when such a continued fraction is expanded to third order in the fields, the familiar small-signal ring-laser theory is obtained.

  1. Bursty, Broadband Electromagnetic Waves Associated with Thin Current Layers and Turbulent Magnetosheath Reconnection

    Science.gov (United States)

    Adrian, M. L.; Wendel, D. E.

    2011-01-01

    We investigate observations of intense bursts of electromagnetic wave energy in association with the thin current layers of turbulent magnetosheath reconnection. These observed emissions form two distinct types: (i) broadband emissions that extend continuously to lOs of Hertz; and (ii) structured bursts of emitted energy that occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed at local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic energy and quantify their proximity to X- and O-nulls, as well as their correlation to the amount of magnetic energy converted by the process of magnetic reconnection.

  2. Stimulated Raman up-conversion of electromagnetic waves by a gyrating electron beam

    Science.gov (United States)

    Sharma, O. P.; Patel, V. L.

    1983-01-01

    A gyrating electron beam supports negative energy modes near the harmonics of electron-cyclotron frequency. An electromagnetic wave passing through such a beam parametrically up-converts into high-frequency electromagnetic modes separated from the pump frequency by the electron-cyclotron harmonics. The growth rate for this process varies directly as the oscillatory velocity of beam electrons caused by the pump and as square root of the beam density. It has a maximum at values of scattering angle close to 180 deg and is also implicitly dependent on the beam veocity and the cyclotron frequency of electrons. The effect of a cold electron component is to reduce the growth rate.

  3. Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mingming, E-mail: lan_mingming@163.com [College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002 (China); Zhang, Deyuan; Cai, Jun; Hu, Yanyan; Yuan, Liming [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2014-07-01

    In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

  4. SHAPE RESTORATIONS OF OBJECT SURFACE ON POLARIZATION STRUCTURE OF REFLECTED ELECTROMAGNETIC WAVE FIELD

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available A problem of electromagnetic wave backscattering on a chosen 3D object is solved. A differential equation which is linked change of polarization coefficient of reflected wave with variation of matrix elements of object scattering is ob- tained. Obtained relation enables to develop algorithms of fast numerical solution of inverse problem of scattering on this object that is determination of complex function of object surface scattering and restoration of unknown object shape on phase distribution of reflected wave. The method uses ray representation of scattering fields based on principle Huygens- Fresnel. The algorithm of object shape restoration on phase of reflected wave allows to restore not only smooth surfaces, but also object surfaces with smaller roughness than a wave length.

  5. Dynamic control of asymmetric electromagnetic wave transmission by active chiral metamaterial.

    Science.gov (United States)

    Chen, Ke; Feng, Yijun; Cui, Li; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-02-16

    The asymmetric transmission of electromagnetic (EM) wave can be fully manipulated by chiral metamaterials, but little can achieve real-time and high efficient tunability due to challenges in practically deployable solutions. Here, we proposed a new scheme for flexibly and dynamically controlling the asymmetric EM wave transmission at microwave frequencies using planar metamaterial of deep subwavelength thickness incorporated with active components of PIN diodes. The asymmetric transmission of linearly polarized EM wave exhibits a high efficiency and a pronounced real-time continuous tunability controlled by the external stimulation of voltage biasing. In addition, the asymmetric transmission effect can be well preserved at large oblique incident angle up to ±70°. The design principle and EM performance are validated by both full wave simulations and experimental measurements. Such dynamically controllable chiral metamaterial may provide robust and flexible approach to manipulate EM wave propagation, as well as to facilitate EM device integration to create diverse functionalities.

  6. Low-frequency electromagnetic waves driven by gyrotropic gyrating ion beams

    Science.gov (United States)

    Sharma, O. P.; Patel, V. L.

    1986-01-01

    The origin of left- and right-hand-polarized low-frequency waves in space plasmas is analyzed. It has been shown that a gyrotropic gyrating ion beam, a ring in velocity space, can excite electromagnetic modes in the plasma near the beam gyrofrequency. It excites left-hand-polarized shear Alfven waves and their harmonics via the coupling of Alfven modes with the beam modes. It can also excite right-hand-polarized fast-mode magnetosonic waves and their harmonics as well. The excitation is possible for beam ions heavier than the plasma ions. The growth rate varies as one-third power of the beam density and decreases with the angle of wave propagation with respect to the ambient magnetic field. The nonlocality has a stabilizing effect on the instability. The predicted values of the wave frequencies compare reasonably well with those observed in satellite data.

  7. Excitation of s-polarized surface electromagnetic waves in inhomogeneous dielectric media.

    Science.gov (United States)

    Kim, Kihong

    2008-08-18

    We consider a model of an inhomogeneous dielectric slab first studied by Shvartzburg, Petite and Auby [J. Opt. Soc. Am. B 16, 966 (1999)] and several variations of that model and study the excitation of s-polarized surface electromagnetic waves on the surface of inhomogeneous dielectric media. Using the invariant imbedding theory of wave propagation in stratified media, we calculate the reflectance and the absorptance of an s wave incident obliquely on a dielectric slab in the Otto configuration, as a function of incident angle and frequency. We also calculate the spatial distribution of the electric field intensity in the inhomogeneous region. We find that in all cases we have considered, s-polarized surface waves are excited at certain incident angles and frequencies. We discuss the physical mechanism of the surface wave generation and the possibility of experimental observations of these effects.

  8. Dynamic control of asymmetric electromagnetic wave transmission by active chiral metamaterial

    Science.gov (United States)

    Chen, Ke; Feng, Yijun; Cui, Li; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-01-01

    The asymmetric transmission of electromagnetic (EM) wave can be fully manipulated by chiral metamaterials, but little can achieve real-time and high efficient tunability due to challenges in practically deployable solutions. Here, we proposed a new scheme for flexibly and dynamically controlling the asymmetric EM wave transmission at microwave frequencies using planar metamaterial of deep subwavelength thickness incorporated with active components of PIN diodes. The asymmetric transmission of linearly polarized EM wave exhibits a high efficiency and a pronounced real-time continuous tunability controlled by the external stimulation of voltage biasing. In addition, the asymmetric transmission effect can be well preserved at large oblique incident angle up to ±70°. The design principle and EM performance are validated by both full wave simulations and experimental measurements. Such dynamically controllable chiral metamaterial may provide robust and flexible approach to manipulate EM wave propagation, as well as to facilitate EM device integration to create diverse functionalities. PMID:28202903

  9. Impact of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    Science.gov (United States)

    Khazanov, G. V.; Gamayunov, K. V.

    2007-01-01

    Effect of the ring current ions in the real part of electromagnetic ion Cyclotron wave dispersion relation is studied on global scale. Recent Cluster observations by Engebretson et al. showed that although the temperature anisotropy of is energetic (> 10 keV) ring current protons was high during the entire 22 November 2003 perigee pass, electromagnetic ion cyclotron waves were observed only in conjunction with intensification of the ion fluxes below 1 keV by over an order of magnitude. To study the effect of the ring current ions on the wave dispersive properties and the corresponding global wave redistribution, we use a self-consistent model of interacting ring current and electromagnetic ion cyclotron waves, and simulate the May 1998 storm. The main findings of our simulation can be summarized as follows: First, the plasma density enhancement in the night MLT sector during the main and recovery storm phases is mostly caused by injection of suprathermal plasma sheet H + (approximately wave dispersion relation leads to a qualitative change of the wave patterns in the postmidnight-dawn sector for L > 4.75. This "new" wave activity is well organized by outward edges of dense suprathermal ring current spots, and the waves are not observed if the ring current ions are not included in the real part of dispersion relation. Third, the most intense wave-induced ring current precipitation is located in the night MLT sector and caused by modification of the wave dispersion relation. The strongest precipitating fluxes of about 8 X 10(exp 6)/ (cm(exp 2) - s X st) are found near L=5.75, MLT=2 during the early recovery phase on 4 May. Finally, the nightside precipitation is more intense than the dayside fluxes, even if there are less intense waves, because the convection field moves ring current ions into the loss cone on the nightside, but drives them out of the loss cone on the dayside. So convection and wave scattering reinforce each other in the nightside, but interfere in

  10. Computational modeling of the electromagnetic characteristics of carbon fiber-reinforced polymer composites with different weave structures

    Science.gov (United States)

    Hassan, A. M.; Douglas, J. F.; Garboczi, E. J.

    2014-02-01

    Carbon fiber reinforced polymer composites (CFRPC) are of great interest in the aerospace and automotive industries due to their exceptional mechanical properties. Carbon fibers are typically woven and inter-laced perpendicularly in warps and wefts to form a carbon fabric that can be embedded in a binding matrix. The warps and wefts can be interlaced in different patterns called weaving structures. The primary weaving structures are the plain, twill, and satin weaves, which give different mechanical composite properties. The goal of this work is to computationally investigate the dependence of CFRPC microwave and terahertz electromagnetic characteristics on weave structure. These bands are good candidates for the Nondestructive Evaluation (NDE) of CFRPC since their wavelengths are comparable to the main weave features. 3D full wave electromagnetic simulations of several different weave models have been performed using a finite element (FEM) simulator, which is able to accurately model the complex weave structure. The computational experiments demonstrate that the reflection of electromagnetic waves from CFRPC depend sensitively on weave structure. The reflection spectra calculated in this work can be used to identify the optimal frequencies for the NDE of each weave structure.

  11. Spatial dependence of electromagnetic ion cyclotron waves triggered by solar wind dynamic pressure enhancements

    Science.gov (United States)

    Cho, J.-H.; Lee, D.-Y.; Noh, S.-J.; Kim, H.; Choi, C. R.; Lee, J.; Hwang, J.

    2017-05-01

    In this paper, using the multisatellite (the Van Allen Probes and two GOES satellites) observations in the inner magnetosphere, we examine two electromagnetic ion cyclotron (EMIC) wave events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field quiet time preconditions. For both events, the impact of enhanced Pdyn causes EMIC waves at multiple points. However, we find a strong spatial dependence that EMIC waves due to enhanced Pdyn impact can occur at multiple points (likely globally but not necessarily everywhere) but with different wave properties. For Event 1, three satellites situated at a nearly same dawnside zone but at slightly different L shells see occurrence of EMIC waves but in different frequencies relative to local ion gyrofrequencies and with different polarizations. These waves are found inside or at the outer edge of the plasmasphere. Another satellite near noon observes no dramatic EMIC wave despite the strongest magnetic compression there. For Event 2, the four satellites are situated at widely separated magnetic local time zones when they see occurrence of EMIC waves. They are again found at different frequencies relative to local ion gyrofrequencies with different polarizations and all outside the plasmasphere. We propose two possible explanations that (i) if triggered by enhanced Pdyn impact, details of ion cyclotron instability growth can be sensitive to local plasma conditions related to background proton distributions, and (ii) there can be preexisting waves with a specific spatial distribution, which determines occurrence and specific properties of EMIC waves depending on satellite's relative position after an enhanced Pdyn arrives.

  12. Mesoscopic correlation with polarization rotation of electromagnetic waves.

    Science.gov (United States)

    Chabanov, A A; Trégourès, N P; van Tiggelen, B A; Genack, A Z

    2004-04-30

    Mesoscopic correlations are observed in the polarization of microwave radiation transmitted through a random waveguide. These measurements, supported by diagrammatic theory, permit an unambiguous decomposition of the intensity correlation function of a vector wave into short, long, and infinite range components. Infinite range correlation that leads to universal conductance fluctuations is measured and found to be in agreement with calculations. The long and infinite range components include nonuniversal frequency-independent terms associated with coupling into and out of the sample.

  13. Nonlinear interactions of electromagnetic waves with the auroral ionosphere

    Science.gov (United States)

    Wong, Alfred Y.

    1999-09-01

    The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.

  14. New combination of composite nanoparticles for improved electromagnetic interference shielding

    OpenAIRE

    Azadmanjiri, Jalal

    2017-01-01

    The scope of this research is to investigate generation and use of new “composite” nanoparticles, in particular conductive and magnetic nanoparticles, and study their potential to improve electromagnetic interference absorption for the high frequency range applications. EMI (electromagnetic interference) shielding is a method to prevent electromagnetic fields flowing between two locations by means of a barrier composed of functional materials. This dissertation presents research finding...

  15. First results of low frequency electromagnetic wave detector of TC-2/Double Star program

    Directory of Open Access Journals (Sweden)

    J. B. Cao

    2005-11-01

    Full Text Available LFEW is a low frequency electromagnetic wave detector mounted on TC-2, which can measure the magnetic fluctuation of low frequency electromagnetic waves. The frequency range is 8 Hz to 10 kHz. LFEW comprises a boom-mounted, three-axis search coil magnetometer, a preamplifier and an electronics box that houses a Digital Spectrum Analyzer. LFEW was calibrated at Chambon-la-Forêt in France. The ground calibration results show that the performance of LFEW is similar to that of STAFF on TC-1. The first results of LFEW show that it works normally on board, and that the AC magnetic interference of the satellite platform is very small. In the plasmasphere, LFEW observed the ion cyclotron waves. During the geomagnetic storm on 8 November 2004, LFEW observed a wave burst associated with the oxygen ion cyclotron waves. This observation shows that during geomagnetic storms, the oxygen ions are very active in the inner magnetosphere. Outside the plasmasphere, LFEW observed the chorus on 3 November 2004. LFEW also observed the plasmaspheric hiss and mid-latitude hiss both in the Southern Hemisphere and Northern Hemisphere on 8 November 2004. The hiss in the Southern Hemisphere may be the reflected waves of the hiss in the Northern Hemisphere.

  16. Electromagnetic wave propagation and wave-vector diagram in space-time periodic media.

    Science.gov (United States)

    Elachi, C.

    1972-01-01

    Analysis of TE and TM wave propagation in space-time periodic media such as dielectrics, isotropic plasmas and uniaxial plasmas. A numerical solution is obtained for media with sinusoidal periodicity. Wave-vector diagrams are plotted to facilitate studies of dipole radiation, wave propagation in waveguides and wave interactions with a half-space.

  17. Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

    Science.gov (United States)

    Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.

    1997-01-01

    We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

  18. Exact solutions for the source-excited cylindrical electromagnetic waves in a nonlinear nondispersive medium.

    Science.gov (United States)

    Es'kin, V A; Kudrin, A V; Petrov, E Yu

    2011-06-01

    The behavior of electromagnetic fields in nonlinear media has been a topical problem since the discovery of materials with a nonlinearity of electromagnetic properties. The problem of finding exact solutions for the source-excited nonlinear waves in curvilinear coordinates has been regarded as unsolvable for a long time. In this work, we present the first solution of this type for a cylindrically symmetric field excited by a pulsed current filament in a nondispersive medium that is simultaneously inhomogeneous and nonlinear. Assuming that the medium has a power-law permittivity profile in the linear regime and lacks a center of inversion, we derive an exact solution for the electromagnetic field excited by a current filament in such a medium and discuss the properties of this solution.

  19. Effects of Millimeter-Wave Electromagnetic Radiation on the Experimental Model of Migraine.

    Science.gov (United States)

    Sivachenko, I B; Medvedev, D S; Molodtsova, I D; Panteleev, S S; Sokolov, A Yu; Lyubashina, O A

    2016-02-01

    Effects of millimeter-wave electromagnetic radiation (40 GHz frequency, 0.01 mW power) on the spontaneous fi ring of convergent neurons of the spinal trigeminal nucleus and their responses to electrical stimulation of the dura mater were studied in neurophysiological experiments on rats. Irradiation of the area of cutaneous receptive fields of spinal trigeminal nucleus reversibly inhibited both spontaneous discharges and activity induced by electrical stimulation of the dura mater. The second and third exposures to electromagnetic radiation with an interval of 10 min were ineffective. These results suggest that suppression of neuronal excitability in the spinal trigeminal ganglion can be a mechanism of the anti-migraine effects of electromagnetic radiation observed in clinical practice.

  20. Propagation of electromagnetic waves in a turbulent medium

    Science.gov (United States)

    Canuto, V. M.; Hartke, G. J.

    1986-01-01

    Theoretical modeling of the wealth of experimental data on propagation of electromagnetic radiation through turbulent media has centered on the use of the Heisenberg-Kolmogorov (HK) model, which is, however, valid only for medium to small sized eddies. Ad hoc modifications of the HK model to encompass the large-scale region of the eddy spectrum have been widely used, but a sound physical basis has been lacking. A model for large-scale turbulence that was recently proposed is applied to the above problem. The spectral density of the temperature field is derived and used to calculate the structure function of the index of refraction N. The result is compared with available data, yielding a reasonably good fit. The variance of N is also in accord with the data. The model is also applied to propagation effects. The phase structure function, covariance of the log amplitude, and variance of the log intensity are calculated. The calculated phase structure function is in excellent agreement with available data.

  1. Harvesting Atmospheric Ions Using Surface Electromagnetic Wave Technologies

    Directory of Open Access Journals (Sweden)

    Louis Wai Yip Liu

    2017-05-01

    Full Text Available For the first time, this paper discloses the use of flowing water for capturing atmospheric ions into a DC electricity. The proposed methodology can be employed to neutralize the positively charged pollutants in air, which are believed to be harmful to our health. Methodology: Atmospheric ions can be collected by a negatively charged antenna which comprises a dielectric layer sandwiched between a top aluminium layer and a bottom lead plate. The top aluminium layer is used to collect the ambient protons, whilst the bottom lead plate is negatively charged by a negative static electricity extracted from flowing water. The voltage has been measured between the top aluminium layer and the bottom lead plate with and without any sunlight. Results: Without any UV light or other electromagnetic disturbance, the generated voltage has rapidly increased from 200 mV to 480 mV within 5 seconds if the bottom lead plate is connected to the negative ion source. Without the negative ion source, however, the output voltage fell to around 10 mV and any significant voltage rise can be observed even in the presence of an UV light. Conclusions: Capturing atmospheric ions is technically feasible. Measured results suggest that, when used in conjunction with a negative ion source, the proposed device can harvest atmospheric ions without any UV light.

  2. Antenna-coupled silicon-organic hybrid integrated photonic crystal modulator for broadband electromagnetic wave detection

    Science.gov (United States)

    Zhang, Xingyu; Hosseini, Amir; Subbaraman, Harish; Wang, Shiyi; Zhan, Qiwen; Luo, Jingdong; Jen, Alex K.; Chung, Chi-jui; Yan, Hai; Pan, Zeyu; Nelson, Robert L.; Lee, Charles Y.; Chen, Ray T.

    2015-03-01

    The detection and measurement of electromagnetic fields have attracted significant amounts of attention in recent years. Traditional electronic electromagnetic field sensors use large active conductive probes which perturb the field to be measured and also make the devices bulky. In order to address these problems, integrated photonic electromagnetic field sensors have been developed, in which an optical signal is modulated by an RF signal collected by a miniaturized antenna. In this work, we design, fabricate and characterize a compact, broadband and highly sensitive integrated photonic electromagnetic field sensor based on a silicon-organic hybrid modulator driven by a bowtie antenna. The large electro-optic (EO) coefficient of organic polymer, the slow-light effects in the silicon slot photonic crystal waveguide (PCW), and the broadband field enhancement provided by the bowtie antenna, are all combined to enhance the interaction of microwaves and optical waves, enabling a high EO modulation efficiency and thus a high sensitivity. The modulator is experimentally demonstrated with a record-high effective in-device EO modulation efficiency of r33=1230pm/V. Modulation response up to 40GHz is measured, with a 3-dB bandwidth of 11GHz. The slot PCW has an interaction length of 300μm, and the bowtie antenna has an area smaller than 1cm2. The bowtie antenna in the device is experimentally demonstrated to have a broadband characteristics with a central resonance frequency of 10GHz, as well as a large beam width which enables the detection of electromagnetic waves from a large range of incident angles. The sensor is experimentally demonstrated with a minimum detectable electromagnetic power density of 8.4mW/m2 at 8.4GHz, corresponding to a minimum detectable electric field of 2.5V/m and an ultra-high sensitivity of 0.000027V/m Hz-1/2 ever demonstrated. To the best of our knowledge, this is the first silicon-organic hybrid device and also the first PCW device used for the

  3. Merger of binary neutron stars: Gravitational waves and electromagnetic counterparts

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Masaru

    2016-12-15

    Late inspiral and merger phases of binary neutron stars are the valuable new experimental fields for exploring nuclear physics because (i) gravitational waves from them will bring information for the neutron-star equation of state and (ii) the matter ejected after the onset of the merger could be the main site for the r-process nucleosynthesis. We will summarize these aspects of the binary neutron stars, describing the current understanding for the merger process of binary neutron stars that has been revealed by numerical-relativity simulations.

  4. Simulating the injection of magnetized plasma without electromagnetic precursor wave

    Science.gov (United States)

    Kilian, Patrick; Spanier, Felix

    2018-01-01

    This note aims to explain how to inject magnetized plasma through an open boundary into the simulation domain of a particle-in-cell simulation. If the magnetic field at the boundary is constant in time, i.e., if magnetized plasma of constant magnetization is injected at a steady rate, this does not present any challenges beyond injecting the particles at a fixed rate and possibly absorbing plasma waves impinging on the wall. If, however, the magnetization or the injection rate changes, a time-varying magnetic field is present. The classical use case for this scenario is a shock front moving through a plasma into the simulation volume.

  5. Conjugate observations of electromagnetic ion cyclotron waves associated with traveling convection vortex events

    Science.gov (United States)

    Kim, Hyomin; Clauer, C. Robert; Gerrard, Andrew J.; Engebretson, Mark J.; Hartinger, Michael D.; Lessard, Marc R.; Matzka, Jürgen; Sibeck, David G.; Singer, Howard J.; Stolle, Claudia; Weimer, Daniel R.; Xu, Zhonghua

    2017-07-01

    We report on simultaneous observations of electromagnetic ion cyclotron (EMIC) waves associated with traveling convection vortex (TCV) events caused by transient solar wind dynamic pressure (Pd) impulse events. The Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft located near the magnetopause observed radial fluctuations of the magnetopause, and the GOES spacecraft measured sudden compressions of the magnetosphere in response to sudden increases in Pd. During the transient events, EMIC waves were observed by interhemispheric conjugate ground-based magnetometer arrays as well as the GOES spacecraft. The spectral structures of the waves appear to be well correlated with the fluctuating motion of the magnetopause, showing compression-associated wave generation. In addition, the wave features are remarkably similar in conjugate hemispheres in terms of bandwidth, quasiperiodic wave power modulation, and polarization. Proton precipitation was also observed by the DMSP spacecraft during the wave events, from which the wave source region is estimated to be 72°-74° in magnetic latitude, consistent with the TCV center. The confluence of space-borne and ground instruments including the interhemispheric, high-latitude, fluxgate/induction coil magnetometer array allows us to constrain the EMIC source region while also confirming the relationship between EMIC waves and the TCV current system.

  6. Resonant absorption of electromagnetic waves in transition anisotropic media.

    Science.gov (United States)

    Kim, Kihong

    2017-11-27

    We study the mode conversion and resonant absorption phenomena occurring in a slab of a stratified anisotropic medium, optical axes of which are tilted with respect to the direction of inhomogeneity, using the invariant imbedding theory of wave propagation. When the tilt angle is zero, mode conversion occurs if the longitudinal component of the permittivity tensor, which is the one in the direction of inhomogeneity in the non-tilted case, varies from positive to negative values within the medium, while the transverse component plays no role. When the tilt angle is nonzero, the wave transmission and absorption show an asymmetry under the sign change of the incident angle in a range of the tilt angle, while the reflection is always symmetric. We calculate the reflectance, the transmittance and the absorptance for several configurations of the permittivity tensor and find that resonant absorption is greatly enhanced when the medium from the incident surface to the resonance region is hyperbolic than when it is elliptic. For certain configurations, the transmittance and absorptance curves display sharp peaks at some incident angles determined by the tilt angle.

  7. Lorentz invariance violation and simultaneous emission of electromagnetic and gravitational waves

    Directory of Open Access Journals (Sweden)

    E. Passos

    2017-09-01

    Full Text Available In this work, we compute some phenomenological bounds for the electromagnetic and massive gravitational high-derivative extensions supposing that it is possible to have an astrophysical process that generates simultaneously gravitational and electromagnetic waves. We present Lorentz invariance violating (LIV higher-order derivative models, following the Myers–Pospelov approach, to electrodynamics and massive gravitational waves. We compute the corrected equation of motion of these models, their dispersion relations and the velocities. The LIV parameters for the gravitational and electromagnetic sectors, ξg and ξγ, respectively, were also obtained for three different approaches: luminal photons, time delay of flight and the difference of graviton and photon velocities. These LIV parameters depend on the mass scales where the LIV-terms become relevant, M for the electromagnetic sector and M1 for the gravitational one. We obtain, using the values for M and M1 found in the literature, that ξg∼10−2, which is expected to be phenomenologically relevant and ξγ∼103, which cannot be suitable for an effective LIV theory. However, we show that ξγ can be interesting in a phenomenological point of view if M≫M1. Finally the relation between the variation of the velocities of the photon and the graviton in relation to the speed of light was calculated and resulted in Δvg/Δvγ≲1.82×10−3.

  8. Lorentz invariance violation and simultaneous emission of electromagnetic and gravitational waves

    Science.gov (United States)

    Passos, E.; Anacleto, M. A.; Brito, F. A.; Holanda, O.; Souza, G. B.; Zarro, C. A. D.

    2017-09-01

    In this work, we compute some phenomenological bounds for the electromagnetic and massive gravitational high-derivative extensions supposing that it is possible to have an astrophysical process that generates simultaneously gravitational and electromagnetic waves. We present Lorentz invariance violating (LIV) higher-order derivative models, following the Myers-Pospelov approach, to electrodynamics and massive gravitational waves. We compute the corrected equation of motion of these models, their dispersion relations and the velocities. The LIV parameters for the gravitational and electromagnetic sectors, ξg and ξγ, respectively, were also obtained for three different approaches: luminal photons, time delay of flight and the difference of graviton and photon velocities. These LIV parameters depend on the mass scales where the LIV-terms become relevant, M for the electromagnetic sector and M1 for the gravitational one. We obtain, using the values for M and M1 found in the literature, that ξg ∼10-2, which is expected to be phenomenologically relevant and ξγ ∼103, which cannot be suitable for an effective LIV theory. However, we show that ξγ can be interesting in a phenomenological point of view if M ≫M1. Finally the relation between the variation of the velocities of the photon and the graviton in relation to the speed of light was calculated and resulted in Δvg / Δvγ ≲ 1.82 ×10-3.

  9. Effect of Electromagnetic Wave on Bone Healing in Fixed and Unfixed Conditions.

    Science.gov (United States)

    Onger, Mehmet Emin; Göçer, Hasan; Çirakli, Alper; Büyükceran, Ismail; Kiliç, Mesut; Kaplan, Süleyman

    2016-09-01

    Mobile phones have come into daily life and are now one of the most frequently used devices for communication. The aim of this study was to evaluate possible effect of electromagnetic wave (EMW) with and without fixation material on bone healing.Forty male rats were exposed to fracture on tibia bone and were randomly divided into 4 groups as E(+)K(+), E(+)K(-), E(-)K(+), and E(-)K(-) where E(+) means EMW exposure and K(+) means Kirschner wire fixation. At the end of study tibia samples were taken from all the groups for the quantitative evaluation of regeneration.Significant difference was found between Group E(+)K(+) and E(-)K(+) in terms of both new bone and capillary volume.Electromagnetic wave may be harmful for bone healing with fixation whereas it has no same effect on bone regeneration without fixation.

  10. Time evolution of electromagnetic wave packets through superlattices: evidence for superluminal velocities.

    Science.gov (United States)

    Pereyra, Pedro; Simanjuntak, Herbert P

    2007-05-01

    We study the space-time evolution of electromagnetic wave packets through optical superlattices. We present rigorous analytical solutions describing the multiple-scattering processes of Gaussian wave packets defined in the band gap and in the resonant energy regions. Following their space-time evolution, we obtain the Maxwell equations prediction for the time spent inside the superlattice. From a close and careful observation of the reflected and transmitted parts of Gaussian packets in a photonic band gap, we conclude unambiguously that the superluminal transmission and the Hartman effect are inherent properties of the electromagnetic theory. It is also shown that the theoretical predictions for the time spent inside an optical superlattice are in good agreement with the experimental results and the phase time predictions.

  11. The involvement of cutaneous receptors in the biological effects of electromagnetic millimeter waves

    Directory of Open Access Journals (Sweden)

    Anton Emil

    2014-01-01

    Full Text Available The involvement of peripheral nerve terminations in the mechanisms of action of electromagnetic millimeter waves (mmW was assessed. It is currently thought that mmW could be used in noninvasive complementary therapy because of their analgesic effect. However, the mechanisms of their antinociceptive effect and non-ionizing radiation are the subjects of controversy. The mechanisms of interaction of mmW and the cutaneous tissue have not been elucidated. We observed mast cell degranulation at the place of mmW action, a decrease of chronaxie and Turck reflex time, an increase in the number of afferent impulses after sciatic nerve at stimulation, as well as an increase electrocardiogram R-R interval of isolated frog heart after application of mmW. Based on these investigations, we propose that electromagnetic waves of millimeter length modify, through indirect mechanisms, the excitability and reactivity of peripheral nerve terminations.

  12. Bone composition and healing: open electromagnetic and biomechanical problems.

    Science.gov (United States)

    Biggane, Peter; Jackson, Xavier; Nazarian, Ara

    2016-08-01

    In this paper, we present a review of some electromagnetic interactions in bone matter. Special attention is paid to pulsed electromagnetic therapy, which is potentially a promising therapeutic method for bone healing. We review and compare existing setups and their applications.

  13. Understanding the gravitational-wave Hellings and Downs curve for pulsar timing arrays in terms of sound and electromagnetic waves

    Science.gov (United States)

    Jenet, Fredrick A.; Romano, Joseph D.

    2015-07-01

    Searches for stochastic gravitational-wave backgrounds using pulsar timing arrays look for correlations in the timing residuals induced by the background across the pulsars in the array. The correlation signature of an isotropic, unpolarized gravitational-wave background predicted by general relativity follows the so-called Hellings and Downs curve, which is a relatively simple function of the angle between a pair of Earth-pulsar baselines. In this paper, we give a pedagogical discussion of the Hellings and Downs curve for pulsar timing arrays, considering simpler analogous scenarios involving sound and electromagnetic waves. We calculate Hellings-and-Downs-type functions for these two scenarios and develop a framework suitable for doing more general correlation calculations.

  14. Initial value problems of cylindrical electromagnetic waves propagation in a nonlinear nondispersive medium.

    Science.gov (United States)

    Chen, Si-Yun; Li, Tong; Xie, Jun-Bin; Xie, Hui; Zhou, Ping; Tian, Yang-Fan; Xiong, Hao; Si, Liu-Gang

    2013-09-01

    We introduce a simple method to estimate the accuracy of exact solutions under initial value conditions proposed by Petrov and Kudrin [Phys. Rev. Lett. 104, 190404 (2010)]. We demonstrate that even for a sufficiently weak nonlinearity, the initial value condition difference between linear and nonlinear case may be evident. Our result may be used as a criterion of employing the exact solution to deal with initial value problems of cylindrical electromagnetic wave propagation in a nonlinear nondispersive medium.

  15. Quasi-one-dimensional ballistic ring in the field of circularly polarized electromagnetic wave

    OpenAIRE

    Epshtein, E. M.; Fedorov, E. G.; Shmelev, G. M.

    2004-01-01

    Dynamics is studied of an electron in a quasi-one-dimensional ballistic ring under circularly polarized electromagnetic field propagating along the normal to the ring plane. The average emission intensity from the ring is calculated. The value and direction of the electron average angular velocity in the ring depend on the incident wave parameters. It is found that the ring average dipole moment can remain constant under certain conditions. Possibility is shown of higher harmonics enhancement...

  16. Electromagnetic Wave Absorption Property of Graphene with FeO4 Nanoparticles.

    Science.gov (United States)

    Yang, Cheng; Dai, Shenglong; Zhang, Xiaoyan; Zhao, Tianyu; Yan, Shaojiu; Zhao, Xiuying

    2016-02-01

    Nanomaterials consisting of various ratios of Fe3O4 and graphene (defined C-Fe3O4/GR) were pre- pared by an in situ coordination complex hydro-thermal synthesis method. The structure and morphology of the nanomaterials C-Fe3O4/GR obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). It was found that the Fe3O4 nanoparticles distributed on the surfaces of graphene, and had a spinel structure and a uniform chemical phase when the weight ratios of Fe3O4 to graphene oxide (GO) were 9:1 or 9:2. It was suggested that GO had been successfully reduced to graphene and the Fe3O4 nanoparticles were chemically bonded to graphene. The SQUID vibrating sample magnetometer (SQUID-VSM) indicated that the maximum of the saturation magnetization was 83.6 emmicro g(-1) when the mass ratio of Fe3O4 to GO was 9:2. Electromagnetic wave absorption showed that the chemical compound of Fe3O4 and graphene had a better electromagnetic property than the mechanical blend of Fe3O4 and graphene (M-Fe3O4/GR). The C-Fe3O4/GR had a reflection loss larger than -10 dB in the frequency range 12.9-17.0 GHz for an absorber thickness of 3 mm, and a maximum reflection loss of -12.3 dB at 14.8 GHz and a maximum reflection loss of -31.2 dB at 10.5 GHz for an absorber thickness of 10 mm. Theoretical analysis showed that the electromagnetic wave absorption behavior obeyed the quarter-wave principles. These results showed that the C-Fe3O4/GR nanomaterials can meet the requirements for some engineering applications, showing great application potential in electromagnetic wave absorption.

  17. Electromagnetic Waves Reflectance of Graphene -- Magnetic Semiconductor Superlattice in Magnetic Field

    OpenAIRE

    Kuzmin, Dmitry A.; Bychkov, Igor V.; Shavrov, Vladimir G.

    2014-01-01

    Electrodynamic properties of the graphene - magnetic semiconductor - graphene superlattice placed in magnetic field have been investigated theoretically in Faraday geometry with taking into account dissipation processes. Frequency and field dependences of the reflectance, transmittance and absorbtance of electromagnetic waves by such superlattice have been calculated for different numbers of periods of the structure and different sizes of the periods with using a transfer matrix method. The p...

  18. Detection of Metallic and Electronic Radar Targets by Acoustic Modulation of Electromagnetic Waves

    Science.gov (United States)

    2017-07-01

    electronic targets within the near field of an ultra-wideband radar antenna operating in the ultra-high frequency band. 15. SUBJECT TERMS radar ...ARL-TR-8076● JULY 2017 US Army Research Laboratory Detection of Metallic and Electronic Radar Targets by Acoustic Modulation of...US Army Research Laboratory Detection of Metallic and Electronic Radar Targets by Acoustic Modulation of Electromagnetic Waves by Gregory

  19. Theory of electromagnetic cyclotron wave growth in a time-varying magnetoplasma

    Science.gov (United States)

    Gail, William B.

    1990-01-01

    The effect of a time-dependent perturbation in the magnetoplasma on the wave and particle populations is investigated using the Kennel-Petchek (1966) approach. Perturbations in the cold plasma density, energetic particle distribution, and resonance condition are calculated on the basis of the ideal MHD assumption given an arbitrary compressional magnetic field perturbation. An equation is derived describing the time-dependent growth rate for parallel propagating electromagnetic cyclotron waves in a time-varying magnetoplasma with perturbations superimposed on an equilibrium configuration.

  20. Electromagnetic Wave Scattering by Small Impedance Particles of an Arbitrary Shape and Applications

    Directory of Open Access Journals (Sweden)

    Alexander G. Ramm

    2014-02-01

    Full Text Available The proposal deals with electromagnetic (EM wave scattering by one and many small impedance particles of an arbitrary shape. Analytic formula is derived for EM wave scattering by one small impedance particle of an arbitrary shape and an integral equation for the effective field in the medium where many such particles are embedded. These results are applied for creating a medium with a desired refraction coefficient. The proposed theory has no analogs in the literature. (Mathematical Subject Classiffication: 35J05, 35J25, 65N12, 78A25, 78A48.

  1. Effects of energetic heavy ions on electromagnetic ion cyclotron wave generation in the plasmapause region

    Science.gov (United States)

    Kozyra, J. U.; Cravens, T. E.; Nagy, A. F.; Fontheim, E. G.; Ong, R. S. B.

    1984-01-01

    An expression for electromagnetic ion cyclotron convective growth rates is derived. The derivation of the dispersion relation and convective growth rates in the presence of a multicomponent energetic and cold plasma is presented. The effects that multiple heavy ions in the ring current and cold plasma produce in the growth and propagation characteristics of ion cyclotron waves are explored. Results of growth rate calculations using parameters consistent with conditions in the plasmapause region during the early recovery phase of geomagnetic storms are presented and compared with ground-based and satellite observations of waves in this region. The geophysical implications of the results are discussed.

  2. Vector wave analysis of an electromagnetic high-order Bessel vortex beam of fractional type α.

    Science.gov (United States)

    Mitri, F G

    2011-03-01

    The scalar wave theory of nondiffracting electromagnetic (EM) high-order Bessel vortex beams of fractional type α has been recently explored, and their novel features and promising applications have been revealed. However, complete characterization of the properties for this new type of beam requires a vector analysis to determine the fields' components in space because scalar wave theory is inadequate to describe such beams, especially when the central spot is comparable to the wavelength (k(r)/k≈1, where k(r) is the radial component of the wavenumber k). Stemming from Maxwell's vector equations and the Lorenz gauge condition, a full vector wave analysis for the electric and magnetic fields is presented. The results are of particular importance in the study of EM wave scattering of a high-order Bessel vortex beam of fractional type α by particles.

  3. Influence of multiple ion species on low-frequency electromagnetic wave instabilities. [in solar wind

    Science.gov (United States)

    Brinca, Armando L.; Tsurutani, Bruce T.

    1989-01-01

    The effect of multiple (singly ionized) coexisting newborn ion species on the stability of low-frequency electromagnetic waves was investigated using a plasma model in which solar wind magnetoplasma is made up of isotropic Maxwellian electron and proton populations with a common number density of 4.95/cu cm and temperatures equal to 17.2 eV and 6.9 eV, respectively. It is shown that the effect of multiple ions on wave growth, for given background magnetoplasma conditions and relative densities, depends not only on their mass but also on the physical nature of the wave modes. If the ion masses are disparate, each one of the coexisting ion beams tends to stimulate instabilities without undue influence from the other species. If the masses of newborn ions are similar, they can strongly catalyze wave growth of fluidlike nonresonant modes, but bring about weak growth enhancements in cyclotron resonant instabilities.

  4. The effect of superluminal phase velocity on electron acceleration in a powerful electromagnetic wave

    Science.gov (United States)

    Robinson, A. P. L.; Arefiev, A. V.; Khudik, V. N.

    2015-08-01

    In this paper, we examine the effect that electromagnetic dispersion has on the motion of an electron in a relativistically strong plane wave. We obtain an analytic solution for the electron momentum and check this solution against direct numerical integration of the equations of motion. The solution shows that even a relatively small difference between the phase velocity of the wave, vp, and the speed of light, c, can significantly alter the electron dynamics if the normalized wave amplitude a0 exceeds √{2 c /(vp-c ) } . At this amplitude, the maximum longitudinal electron momentum scales only linearly with a0, as opposed to a02 . We also show that at this amplitude the impact of an accelerating longitudinal electric field and electron pre-acceleration is negated by the superluminous phase velocity of the wave. This has implications for the potential of Direct Laser Acceleration of electrons. We point out that electromagnetic dispersion can arise from both propagation in a plasma and from propagating the laser in what is effectively a wave-guiding structure, and that this latter source of dispersion is likely to be more significant.

  5. Nonlinear interaction of electromagnetic waves with 3-component relativistic quantum plasma

    Science.gov (United States)

    Ikramullah, Ahmad, Rashid; Sharif, Saqib; Khattak, Fida Younus

    2017-05-01

    The interaction of intense circularly polarized electro-magnetic (CPEM) wave with 3-component relativistic-quantum plasma consisting of relativistic-degenerate electrons and positrons, and dynamic degenerate ions is theoretically studied. A mathematical model is structured by coupling Klein-Gordon equations for the electrons and positrons, and Schrödinger equation for the ions with Maxwell equations through Poisson equations. The solutions of the dispersion relation are plotted for relativistic quantum plasma in the density-range of ˜ 10 30 → 10 36 m - 3 for several positron concentrations. Three wave modes are observed: electrons, ions, and positrons. The pair branch mode having a possible association with the positron states stays unaltered by variation in the positron concentration but varies significantly with a change in the quantum parameter defined in terms of the particles number density. The addition of positron to the plasma and increasing the positron concentration suggest enhancement of the opacity of the relativistic quantum plasma. The nonlinear interaction of large amplitude CPEM waves with the plasma leads to self-induced transparency. The transparency decreases with increasing positron concentration. The model so developed is then applied to study stimulated Raman scattering, modulational instability, and stimulated Brillouin scattering of intense CPEM waves in such plasmas. The results show that the growth rates are affected by the positron concentration, the quantum parameter of the plasma, as well as by the amplitude of the incident electromagnetic wave.

  6. Fabrication process and electromagnetic wave absorption characterization of a CNT/Ni/epoxy nanocomposite.

    Science.gov (United States)

    Ryu, Seongwoo; Mo, Chan Bin; Lee, Haeshin; Hong, Soon Hyung

    2013-11-01

    Since carbon nanotube (CNT) was first discovered in 1991, it has been considered as a viable type of conductive filler for electromagnetic wave absorption materials in the GHz range. In this paper, pearl-necklace-structure CNT/Ni nano-powders were fabricated by a polyol process as conductive fillers. Compared to synthesized CNT, pearl-necklace Ni-decorated CNT increased the electrical conductivity by an order of 1 due to the enhancement of the Ni-conductive network. Moreover, the decorated Ni particles prevented the agglomeration of CNTs by counterbalancing the Van der Walls interaction between the CNTs. A CNT/Ni nanocomposite showed a homogeneous dispersion in an epoxy-based matrix. This enhanced physical morphology and electrical properties lead to an increase in the loss tangent and reflection loss in the CNT/Ni/Epoxy nanocomposite compared to these characteristics of a CNT/Epoxy nanocomposite in range of 8-12 GHz. The electromagnetic wave absorption properties of CNT/Ni/epoxy nanocomposites will provide enormous opportunities for electronic applications where lightweight EMI shielding or electro-magnetic wave absorption properties are necessary.

  7. Electromagnetic design of an all-diffractive millimeter-wave imaging system.

    Science.gov (United States)

    Chen, Caihua; Shi, Shouyan; Prather, Dennis W

    2004-04-20

    We present the design and electromagnetic analysis of an all-diffractive millimeter-wave imaging system having a field of view of +/- 15 degrees. This system consists of two 16-level diffractive lenses, with the stop in contact with the first lens. By considering the Seidel aberrations for a diffractive lens and applying the corresponding stop shift formula, we established the expressions of third-order wave aberrations for this system. By setting all primary Seidel aberrations to zero and solving the corresponding system of equations, we obtained two sets of solutions for this two-element all-diffractive system, which totally compensate for all Seidel aberrations. To assess image system performance, we apply the finite-difference time-domain technique and a vector plane-wave spectrum method, in combination, to validate the performance of the system. To reduce the computational cost and thereby enable the complete electromagnetic analysis of the system, a four-step analysis procedure has been developed and applied as an electromagnetic system model.

  8. Extracorporeal shock-wave lithotripsy: a comparative study of electrohydraulic and electromagnetic units.

    Science.gov (United States)

    Matin, S F; Yost, A; Streem, S B

    2001-12-01

    We determined the results of shock wave lithotripsy with a newer electromagnetic lithotriptor and compared them with those in a contemporary series of cases managed by an electrohydraulic lithotriptor using identical treatment and followup criteria at a single center. Between 1995 and 1999, 356 patients (375 renal units, 483 upper urinary tract stones) meeting study inclusion criteria were treated with an MFL 5000 electrohydraulic shock wave lithotripsy unit (Dornier Medical Systems, Inc., Marietta, Georgia). From 1999 to 2000, 173 patients (175 renal units; 218 upper urinary tract stones) meeting identical study inclusion criteria were treated using an electromagnetic Modulith SLX shock wave lithotripsy unit (Karl Storz Lithotripsy, Atlanta, Georgia). In each group stone-free results were determined by plain abdominal x-ray and renal ultrasound 1 month after lithotripsy and efficiency quotients were developed. Baseline patient and stone characteristics were compared by the Wilcoxon rank sum and Fisher exact tests. All variables significant at p electromagnetic lithotripsy units (0.45 and 0.42, respectively, p = 0.43). Electrohydraulic lithotripsy resulted in a higher stone-free rate at 1 month, although it was associated with a higher rate of auxiliary measures. Ultimately the efficiency quotients were equivalent, implying that these 2 contemporary energy sources are acceptable. According to single center treatment and followup criteria they are equally efficacious.

  9. A new method to solve non-homogeneous wave equations of electromagnetic fields by fourier’s triple integral transform

    Science.gov (United States)

    Hu, Wenjing

    2017-08-01

    This paper uses Fourier’s triple integral transform method to simplify the calculation of the non-homogeneous wave equations of the time-varying electromagnetic field. By adding several special definite conditions to the wave equation, it becomes a mathematical problem of definite condition. Then by using Fourier’s triple integral transform method, this three-dimension non-homogeneous partial differential wave equation is changed into an ordinary differential equation. Through the solution to this ordinary differential equation, the expression of the relationship between the time-varying scalar potential and electromagnetic wave excitation source is developed precisely. This method simplifies the solving process effectively.

  10. THE ROLE OF SUPERLUMINAL ELECTROMAGNETIC WAVES IN PULSAR WIND TERMINATION SHOCKS

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Takanobu [Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033 (Japan); Kirk, John G., E-mail: amano@eps.s.u-tokyo.ac.jp [Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany)

    2013-06-10

    The dynamics of a standing shock front in a Poynting-flux-dominated relativistic flow is investigated by using a one-dimensional, relativistic, two-fluid simulation. An upstream flow containing a circularly polarized, sinusoidal magnetic shear wave is considered, mimicking a wave driven by an obliquely rotating pulsar. It is demonstrated that this wave is converted into large-amplitude electromagnetic waves with superluminal phase speeds by interacting with the shock when the shock-frame frequency of the wave exceeds the proper plasma frequency. The superluminal waves propagate in the upstream, modify the shock structure substantially, and form a well-developed precursor region ahead of a subshock. Dissipation of Poynting flux occurs in the precursor as well as in the downstream region through a parametric instability driven by the superluminal waves. The Poynting flux remaining in the downstream region is carried entirely by the superluminal waves. The downstream plasma is therefore an essentially unmagnetized, relativistically hot plasma with a non-relativistic flow speed, as suggested by observations of pulsar wind nebulae.

  11. Low-Intensity Electromagnetic Millimeter Waves for Pain Therapy

    Directory of Open Access Journals (Sweden)

    Taras I. Usichenko

    2006-01-01

    Full Text Available Millimeter wave therapy (MWT, a non-invasive complementary therapeutic technique is claimed to possess analgesic properties. We reviewed the clinical studies describing the pain-relief effect of MWT. Medline-based search according to review criteria and evaluation of methodological quality of the retrieved studies was performed. Of 13 studies, 9 of them were randomized controlled trials (RCTs, only three studies yielded more than 3 points on the Oxford scale of methodological quality of RCTs. MWT was reported to be effective in the treatment of headache, arthritic, neuropathic and acute postoperative pain. The rapid onset of pain relief during MWT lasting hours to days after, remote to the site of exposure (acupuncture points, was the most characteristic feature in MWT application for pain relief. The most commonly used parameters of MWT were the MW frequencies between 30 and 70 GHz and power density up to 10 mW cm−2. The promising results from pilot case series studies and small-size RCTs for analgesic/hypoalgesic effects of MWT should be verified in large-scale RCTs on the effectiveness of this treatment method.

  12. Group velocity of cylindrical guided waves in anisotropic laminate composites.

    Science.gov (United States)

    Glushkov, Evgeny; Glushkova, Natalia; Eremin, Artem; Lammering, Rolf

    2014-01-01

    An explicit expression for the group velocity of wave packets, propagating in a laminate anisotropic composite plate in prescribed directions, is proposed. It is based on the cylindrical guided wave asymptotics derived from the path integral representation for wave fields generated in the composites by given localized sources. The expression derived is theoretically confirmed by the comparison with a known representation for the group velocity vector of a plane guided wave. Then it is experimentally validated against laser vibrometer measurements of guided wave packets generated by a piezoelectric wafer active sensor in a composite plate.

  13. Thin and Flexible Fe-Si-B/Ni-Cu-P Metallic Glass Multilayer Composites for Efficient Electromagnetic Interference Shielding.

    Science.gov (United States)

    Zhang, Jijun; Li, Jiawei; Tan, Guoguo; Hu, Renchao; Wang, Junqiang; Chang, Chuntao; Wang, Xinmin

    2017-11-20

    Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, especially if they can be easily processed and withstand harsh environments. Herein, layer-structured Fe-Si-B/Ni-Cu-P metallic glass composites have been developed by simple electroless plating Ni-Cu-P coating on commercial Fe-Si-B metallic glasses. The 0.1 mm-thick composite shows EMI shielding effectiveness of 40 dB over the X-band frequency range, which is higher than those of traditional metals, metal oxides, and their polymer composites of larger thickness. Most of the applied electromagnetic waves are proved to be absorbed rather than bounced back. This performance originates from the combination of a superior soft magnetic property, excellent electrical conductivity, and multiple internal reflections from multilayer composites. In addition, the flexible composites also exhibit good corrosion resistance, high thermal stability, and excellent tensile strength, making them suitable for EMI shielding in harsh chemical or thermal environments.

  14. A simple, one-step hydrothermal approach to durable and robust superparamagnetic, superhydrophobic and electromagnetic wave-absorbing wood

    Science.gov (United States)

    Wang, Hanwei; Yao, Qiufang; Wang, Chao; Fan, Bitao; Sun, Qingfeng; Jin, Chunde; Xiong, Ye; Chen, Yipeng

    2016-10-01

    In this work, lamellar MnFe2O4 was successfully planted on a wood surface through the association of hydrogen bonds via the one-pot hydrothermal method. Simultaneously, the fluoroalkylsilane (FAS-17) on the surface of the MnFe2O4 layer formed long-chain or network macromolecules through a poly-condensation process and provided a lower surface energy on the wood surface. The MnFe2O4/wood composite (FMW) presented superior superparamagnetism, superhydrophobicity and electromagnetic wave absorption performance. The results indicated a saturation magnetization of the FMW with excellent superparamagnetism of 28.24 emu·g-1. The minimum value of reflection loss of the FMW reached -8.29 dB at 16.39 GHz with a thickness of 3 mm. Even after mechanical impact and exposure to corrosive liquids, the FMW still maintained a superior superhydrophobicity performance.

  15. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, Arnold, E-mail: qulaser@gmail.com [Kuang-Chi Institute of Advanced Technology, Shenzhen, 518057 (China); Kostikov, Alexander [Donbass State Engineering Academy, 84303, Kramatorsk, Donetsk (Ukraine)

    2017-03-26

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder. - Highlights: • We consider scattering of electromagnetic plane waves by two cylinders. • WGMs occur because of the presence of additional cylinder at specific location. • The accuracy for the locations is much less than required for specific values of single cylinder. • The interference of waves scattered by additional cylinders and incident on the main is responsible for the effect.

  16. Propagation of electromagnetic waves in a weak collisional and fully ionized dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jieshu; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn; Gao, Ruilin; Wang, Ying; Zhou, Zhong-Xiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Liu, Sha; Yue, Feng [Shanghai Institute of Spaceflight Control Technology, Shanghai 200233 (China); Wu, Jian [China Research Institute of Radio wave Propagation, Beijing 102206 (China); Li, Hui [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); China Research Institute of Radio wave Propagation, Beijing 102206 (China)

    2016-04-15

    The propagation properties of electromagnetic (EM) waves in fully ionized dusty plasmas is the subject of this study. The dielectric relationships for EM waves propagating in a fully ionized dusty plasma was derived from the Boltzmann distribution law, taking into consideration the collision and charging effects of the dust grains. The propagation properties of the EM waves in a dusty plasma were numerically calculated and studied. The study results indicated that the dusty grains with an increased radius and charge were more likely to impede the penetration of EM waves. Dust grains with large radii and high charge cause the attenuation of the EM wave in the dusty plasma. The different density of the dust in the plasma appeared to have no obvious effect on the transmission of the EM waves. The propagation of the EM waves in a weakly ionized dusty plasma varies from that in a fully ionized dusty plasma. The results are helpful to analyze the effects of dust in dusty plasmas and also provide a theoretical basis for future studies.

  17. Multiple scattering of electromagnetic waves by an aggregate of uniaxial anisotropic spheres.

    Science.gov (United States)

    Li, Zheng-Jun; Wu, Zhen-Sen; Shi, Yan'e; Bai, Lu; Li, Hai-Ying

    2012-01-01

    An exact analytical solution is obtained for the scattering of electromagnetic waves from a plane wave with arbitrary directions of propagation and polarization by an aggregate of interacting homogeneous uniaxial anisotropic spheres with parallel primary optical axes. The expansion coefficients of a plane wave with arbitrary directions of propagation and polarization, for both TM and TE modes, are derived in terms of spherical vector wave functions. The effects of the incident angle α and the polarization angle β on the radar cross sections (RCSs) of several types of collective uniaxial anisotropic spheres are numerically analyzed in detail. The characteristics of the forward and backward RCSs in relation to the incident wavelength are also numerically studied. Selected results on the forward and backward RCSs of several types of square arrays of SiO₂ spheres illuminated by a plane wave with different incident angles are described. The accuracy of the expansion coefficients of the incident fields is verified by comparing them with the results obtained from references when the plane wave is degenerated to a z-propagating and x- or y-polarized plane wave. The validity of the theory is also confirmed by comparing the numerical results with those provided by a CST simulation.

  18. Parallel Propagation of Electromagnetic Waves in a Partially Ionized Plasma with Multiple Species

    Science.gov (United States)

    Huang, Y.; Song, P.; Tu, J.

    2016-12-01

    When waves propagate along the magnetic field in a partially ionized plasma with two or more ion species e.g. H+ and O+, such as in the Earth's ionosphere, because of the differences in mass and density, each species responds to the perturbations of electromagnetic fields differently. Furthermore, collisions among the different ions species, between ions and electrons, and between ions and neutrals also affect the wave propagation. With the linear analysis and the assumption of cold plasma, the general dispersion relation of propagation covering all frequencies, from MHD waves to the light propagation, in a medium with arbitrary species of ions, anions and neutrals is derived from the multiple fluids treatment, in combination with Faraday's Law and Ampere's Law including the displacement current. There are several stop bands and characteristic frequencies. For each ion or anion species, there is a resonant frequency at its cyclotron frequency and a cutoff frequency which depends on the mass density of the speciesand and the magnetic field. The waves are strongly damped at the resonant frequencies and become reflective at the cutoff frequencies. With the collisions, the wave propagates slower than the Alfven speed with the frequency below the ion-neutral collision frequency because of an inertia loading process by neutrals. When the collisions are stronger, the resonance is weaker as the cyclotron motion of the ions is disrupted frequently by the collisions. The roles of the collisions played in wave propagation in the stop bands and in wave damping will be discussed.

  19. Facile Synthesis of Novel Heterostructure Based on SnO2 Nanorods Grown on Submicron Ni Walnut with Tunable Electromagnetic Wave Absorption Capabilities.

    Science.gov (United States)

    Zhao, Biao; Fan, Bingbing; Shao, Gang; Zhao, Wanyu; Zhang, Rui

    2015-08-26

    In this work, the magnetic-dielectric core-shell heterostructure composites with the core of Ni submicron spheres and the shell of SnO2 nanorods were prepared by a facile two-step route. The crystal structure and morphology were investigated by X-ray diffraction analysis, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). FESEM and TEM measurements present that SnO2 nanorods were perpendicularly grown on the surfaces of Ni spheres and the density of the SnO2 nanorods could be tuned by simply varying the addition amount of Sn(2+) in this process. The morphology of Ni/SnO2 composites were also determined by the concentration of hydrochloric acid and a plausible formation mechanism of SnO2 nanorods-coated Ni spheres was proposed based on hydrochloric acid concentration dependent experiments. Ni/SnO2 composites exhibit better thermal stability than pristine Ni spheres based on thermalgravimetric analysis (TGA). The measurement on the electromagnetic (EM) parameters indicates that SnO2 nanorods can improve the impedance matching condition, which is beneficial for the improvement of electromagnetic wave absorption. When the coverage density of SnO2 nanorod is in an optimum state (diameter of 10 nm and length of about 40-50 nm), the optimal reflection loss (RL) of electromagnetic wave is -45.0 dB at 13.9 GHz and the effective bandwidth (RL below -10 dB) could reach to 3.8 GHz (12.3-16.1 GHz) with the absorber thickness of only 1.8 mm. By changing the loading density of SnO2 nanorods, the best microwave absorption state could be tuned at 1-18 GHz band. These results pave an efficient way for designing new types of high-performance electromagnetic wave absorbing materials.

  20. Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Foteinopoulou, Stavroula [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals, i.e., structures with periodic dielectric patterns on a plane and translational symmetry in the perpendicular direction. They start by studying a two-dimensional photonic crystal system for frequencies inside the band gap. The inclusion of a line defect introduces allowed states in the otherwise prohibited frequency spectrum. The dependence of the defect resonance state on different parameters such as size of the structure, profile of incoming source, etc., is investigated in detail. For this study, they used two popular computational methods in photonic crystal research, the Finite Difference Time Domain method (FDTD) and the Transfer Matrix Method (TMM). The results for the one-dimensional defect system are analyzed, and the two methods, FDTD and TMM, are compared. Then, they shift their attention only to periodic two-dimensional crystals, concentrate on their band properties, and study their unusual refractive behavior. Anomalous refractive phenomena in photonic crystals included cases where the beam refracts on the ''wrong'' side of the surface normal. The latter phenomenon, is known as negative refraction and was previously observed in materials where the wave vector, the electric field, and the magnetic field form a left-handed set of vectors. These materials are generally called left-handed materials (LHM) or negative index materials (NIM). They investigated the possibility that the photonic crystal behaves as a LHM, and how this behavior relates

  1. On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2017-10-01

    Full Text Available This study analyzed the transformer electromagnetic gap propagation characteristics. The influence of gap size is also analyzed, and the results experimentally verified. The obtained results indicated that the gap propagation characteristics of electromagnetic wave signals radiated by the partial discharge (PD source in different directions are substantially different. The intensity of the electromagnetic wave in the gap reaches a maximum at a gap height of 1 cm; and inside the gap, the intensity of the electromagnetic wave depicted an increasing trend at the tail area of the gap. Finally, from the obtained results, some suggestions on where to install sensors in practical systems for ultra high frequency (UHF PD signal detection in the transformer gap are provided. The obtained results confirmed the feasibility of using this approach. These results can be seen as a benchmark and a challenge for further research in this field.

  2. Lightweight, multifunctional polyetherimide/graphene@Fe3O4 composite foams for shielding of electromagnetic pollution.

    Science.gov (United States)

    Shen, Bin; Zhai, Wentao; Tao, Mimi; Ling, Jianqiang; Zheng, Wenge

    2013-11-13

    Novel high-performance polyetherimide (PEI)/graphene@Fe3O4 (G@Fe3O4) composite foams with flexible character and low density of about 0.28-0.4 g/cm(3) have been developed by using a phase separation method. The obtained PEI/G@Fe3O4 foam with G@Fe3O4 loading of 10 wt % exhibited excellent specific EMI shielding effectiveness (EMI SE) of ~41.5 dB/(g/cm(3)) at 8-12 GHz. Moreover, most the applied microwave was verified to be absorbed rather than being reflected back, resulting from the improved impedance matching, electromagnetic wave attenuation, as well as multiple reflections. Meanwhile, the resulting foams also possessed a superparamagnetic behavior and low thermal conductiviy of 0.042-0.071 W/(m K). This technique is fast, highly reproducible, and scalable, which may facilitate the commercialization of such composite foams and generalize the use of them as EMI shielding materials in the fields of spacecraft and aircraft.

  3. Monitoring dynamic reactions of red blood cells to UHF electromagnetic waves radiation using a novel micro-imaging technology.

    Science.gov (United States)

    Ruan, Ping; Yong, Junguang; Shen, Hongtao; Zheng, Xianrong

    2012-12-01

    Multiple state-of-the-art techniques, such as multi-dimensional micro-imaging, fast multi-channel micro-spetrophotometry, and dynamic micro-imaging analysis, were used to dynamically investigate various effects of cell under the 900 MHz electromagnetic radiation. Cell changes in shape, size, and parameters of Hb absorption spectrum under different power density electromagnetic waves radiation were presented in this article. Experimental results indicated that the isolated human red blood cells (RBCs) do not have obviously real-time responses to the ultra-low density (15 μW/cm(2), 31 μW/cm(2)) electromagnetic wave radiation when the radiation time is not more than 30 min; however, the cells do have significant reactions in shape, size, and the like, to the electromagnetic waves radiation with power densities of 1 mW/cm(2) and 5 mW/cm(2). The data also reveal the possible influences and statistical relationships among living human cell functions, radiation amount, and exposure time with high-frequency electromagnetic waves. The results of this study may be significant on protection of human being and other living organisms against possible radiation affections of the high-frequency electromagnetic waves.

  4. Three-Dimensional Transient Electromagnetic Modeling Based on Fictitious Wave Domain Methods

    Science.gov (United States)

    Ji, Yanju; Hu, Yanpu; Imamura, Naoto

    2017-05-01

    Finite-difference time domain (FDTD) methods, which have been widely employed in three-dimensional transient electromagnetic (TEM) modeling, require very small time steps to simulate the electromagnetic fields and this will be time consuming. We present an efficient numerical method for three-dimensional TEM forward modeling. Its key features are based on a correspondence principle between the diffusive and fictitious wave fields. The diffusive Maxwell's equations are transformed and solved in a so-called fictitious wave domain. This scheme allows larger time steps than conventional FDTD methods, allows including air layers, and allows simulating topography. The need for initial field calculations is avoided by including an electric current source in the governing equations. This also avoids a traditional assumption of a flat earth surface in TEM modeling. We test the accuracy of the electromagnetic fields' responses using our method with the spectral differential difference (SLDM) solutions. The results show good agreement even under the existence of air layers and topography in the model.

  5. Hunting Electromagnetic Counterparts of Gravitational-wave Events Using the Zwicky Transient Facility

    Science.gov (United States)

    Ghosh, Shaon; Chatterjee, Deep; Kaplan, David L.; Brady, Patrick R.; Van Sistine, Angela

    2017-11-01

    Detections of coalescing binary black holes by LIGO have opened a new window of transient astronomy. With increasing sensitivity of LIGO and participation of the Virgo detector in Cascina, Italy, we expect to soon detect coalescence of compact binary systems with one or more neutron stars. These are the prime targets for electromagnetic follow-up of gravitational wave triggers, which holds enormous promise of rich science. However, hunting for electromagnetic counterparts of gravitational wave events is a non-trivial task due to the sheer size of the error regions, which could span hundreds of square degrees. This may require deep observation with large field-of-view telescopes and/or use of galaxy catalogs. The Zwicky Transient facility (ZTF), scheduled to begin operation in 2017, is designed to cover such large sky-localization areas. In this work, we present the strategies of efficiently tiling the sky to facilitate the observation of the gravitational wave error regions using ZTF. To do this, we used simulations consisting of 475 binary neutron star coalescences detected using a mix of two- and three-detector networks. Our studies reveal that, using two overlapping sets of ZTF tiles and a (modified) ranked-tiling algorithm, we can cover the gravitational-wave sky-localization regions with half as many pointings as a simple contour-covering algorithm. We then incorporated the ranked-tiling strategy to study our ability to observe the counterparts. This requires optimization of observation depth and localization area coverage. Our results show that observation in r-band with ˜600 seconds of integration time per pointing seems to be optimum for typical assumed brightnesses of electromagnetic counterparts, if we plan to spend equal amount of time per pointing. However, our results also reveal that we can gain by as much as 50% in detection efficiency if we linearly scale our integration time per pointing based on the tile probability.

  6. Hunting Electromagnetic Counterparts of Gravitational-wave Events Using the Zwicky Transient Facility

    Science.gov (United States)

    Ghosh, Shaon; Chatterjee, Deep; Kaplan, David L.; Brady, Patrick R.; Van Sistine, Angela

    2017-11-01

    Detections of coalescing binary black holes by LIGO have opened a new window of transient astronomy. With increasing sensitivity of LIGO and participation of the Virgo detector in Cascina, Italy, we expect to soon detect coalescence of compact binary systems with one or more neutron stars. These are the prime targets for electromagnetic follow-up of gravitational wave triggers, which holds enormous promise of rich science. However, hunting for electromagnetic counterparts of gravitational wave events is a non-trivial task due to the sheer size of the error regions, which could span hundreds of square degrees. This may require deep observation with large field-of-view telescopes and/or use of galaxy catalogs. The Zwicky Transient facility (ZTF), scheduled to begin operation in 2017, is designed to cover such large sky-localization areas. In this work, we present the strategies of efficiently tiling the sky to facilitate the observation of the gravitational wave error regions using ZTF. To do this, we used simulations consisting of 475 binary neutron star coalescences detected using a mix of two- and three-detector networks. Our studies reveal that, using two overlapping sets of ZTF tiles and a (modified) ranked-tiling algorithm, we can cover the gravitational-wave sky-localization regions with half as many pointings as a simple contour-covering algorithm. We then incorporated the ranked-tiling strategy to study our ability to observe the counterparts. This requires optimization of observation depth and localization area coverage. Our results show that observation in r-band with ∼600 seconds of integration time per pointing seems to be optimum for typical assumed brightnesses of electromagnetic counterparts, if we plan to spend equal amount of time per pointing. However, our results also reveal that we can gain by as much as 50% in detection efficiency if we linearly scale our integration time per pointing based on the tile probability.

  7. Electromagnetic wave scattering in a two-layer anisotropic random medium

    Science.gov (United States)

    Lee, J. K.; Kong, J. A.

    1985-01-01

    For electromagnetic wave propagation and scattering in an anisotropic random medium, the Dyson equation for the mean field and the Bethe-Salpeter equation for the correlation or the covariance of the field were derived. With the random permittivity expressed in a general anisotropic form, the bilocal and the nonlinear approximations are employed to solve the Dyson equation, and the ladder approximation to solve the Bethe-Salpeter equation. The mean dyadic Green's function for a two-layer anisotropic random medium with arbitrary three-dimensional correlation functions has been investigated with the zeroth-order solutions to the Dyson equation under the nonlinear approximation. The effective propagation constants are calculated for the four characteristic waves associated with the coherent vector fields, propagating in an anisotropic random-medium layer, which are the ordinary and extraordinary waves with upward- and downward-propagating vectors.

  8. Amplification of a high-frequency electromagnetic wave by a relativistic plasma

    Science.gov (United States)

    Yoon, Peter H.

    1990-01-01

    The amplification of a high-frequency transverse electromagnetic wave by a relativistic plasma component, via the synchrotron maser process, is studied. The background plasma that supports the transverse wave is considered to be cold, and the energetic component whose density is much smaller than that of the background component has a loss-cone feature in the perpendicular momentum space and a finite field-aligned drift speed. The ratio of the background plasma frequency squared to the electron gyrofrequency squared is taken to be sufficiently larger than unity. Such a parameter regime is relevant to many space and astrophysical situations. A detailed study of the amplification process is carried out over a wide range of physical parameters including the loss-cone index, the ratio of the electron mass energy to the temperature of the energetic component, the field-aligned drift speed, the normalized density, and the wave propagation angle.

  9. Construction of three-dimensional graphene interfaces into carbon fiber textiles for increasing deposition of nickel nanoparticles: flexible hierarchical magnetic textile composites for strong electromagnetic shielding.

    Science.gov (United States)

    Bian, Xing-Ming; Liu, Lin; Li, Hai-Bing; Wang, Chan-Yuan; Xie, Qing; Zhao, Quan-Liang; Bi, Song; Hou, Zhi-Ling

    2017-01-27

    Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.

  10. Construction of three-dimensional graphene interfaces into carbon fiber textiles for increasing deposition of nickel nanoparticles: flexible hierarchical magnetic textile composites for strong electromagnetic shielding

    Science.gov (United States)

    Bian, Xing-Ming; Liu, Lin; Li, Hai-Bing; Wang, Chan-Yuan; Xie, Qing; Zhao, Quan-Liang; Bi, Song; Hou, Zhi-Ling

    2017-01-01

    Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.

  11. Electromagnetic counterparts to gravitational waves from black hole mergers and naked singularities

    CERN Document Server

    Malafarina, Daniele

    2016-01-01

    We consider the question here whether the proposed electromagnetic counterpart of the gravitational wave signals in binary black hole coalescence may be due to the appearance of a `short lived' naked singularity during the merger. We point out that the change in topology that the spacetime undergoes during the merger can cause the appearance of a naked singularity. In case some matter, in the form of a small accretion disk, is present in the surroundings of the black hole system then the emitted luminosity during the merger would allow to distinguish the scenario where the naked singularity forms from the scenario where the horizon exists at all times. In fact the emitted luminosity spectrum would be much higher in the case where a naked singularity forms as opposed to the `pure' black hole case. We suggest that the presence of such a transient naked singularity will explain the high luminosity of an electromagnetic counterpart during the merger much more easily.

  12. Transition operators in electromagnetic-wave diffraction theory. II - Applications to optics

    Science.gov (United States)

    Hahne, G. E.

    1993-01-01

    The theory developed by Hahne (1992) for the diffraction of time-harmonic electromagnetic waves from fixed obstacles is briefly summarized and extended. Applications of the theory are considered which comprise, first, a spherical harmonic expansion of the so-called radiation impedance operator in the theory, for a spherical surface, and second, a reconsideration of familiar short-wavelength approximation from the new standpoint, including a derivation of the so-called physical optics method on the basis of quasi-planar approximation to the radiation impedance operator, augmented by the method of stationary phase. The latter includes a rederivation of the geometrical optics approximation for the complete Green's function for the electromagnetic field in the presence of a smooth- and a convex-surfaced perfectly electrically conductive obstacle.

  13. Bursty, Broadband Electromagnetic Waves Associated with Three-Dimensional Nulls Observed in Turbulent Magnetosheath Reconnection

    Science.gov (United States)

    Adrian, Mark L.; Wendel, D. E.

    2012-01-01

    We investigate observations of intense bursts of electromagnetic wave energy in association with the thin current layers of turbulent magnetosheath reconnection. These observed emissions - typically detected in the layers immediately outside of the current layer proper - form two distinct types: (i) broadband emissions that extend continuously to lOs of Hertz; and (ii) structured bursts of emitted energy that occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed near the local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic energy and quantify their proximity to X-IO-nulls and magnetic spine connected null pairs, as well as their correlation - if any - to the amount of magnetic energy converted by the process of magnetic reconnection.

  14. Global Evolutionary Algorithms in the Design of Electromagnetic Band Gap Structures with Suppressed Surface Waves Propagation

    Directory of Open Access Journals (Sweden)

    P. Kovacs

    2010-04-01

    Full Text Available The paper is focused on the automated design and optimization of electromagnetic band gap structures suppressing the propagation of surface waves. For the optimization, we use different global evolutionary algorithms like the genetic algorithm with the single-point crossover (GAs and the multi-point (GAm one, the differential evolution (DE and particle swarm optimization (PSO. The algorithms are mutually compared in terms of convergence velocity and accuracy. The developed technique is universal (applicable for any unit cell geometry. The method is based on the dispersion diagram calculation in CST Microwave Studio (CST MWS and optimization in Matlab. A design example of a mushroom structure with simultaneous electromagnetic band gap properties (EBG and the artificial magnetic conductor ones (AMC in the required frequency band is presented.

  15. Incomplete LU preconditioning for large scale dense complex linear systems from electromagnetic wave scattering problems

    CERN Document Server

    Lee Jeong Hwa

    2003-01-01

    We consider the preconditioned iterative solution of large dense linear systems, where the coefficient matrix is a complex valued matrix arising from discretizing the integral equation of electromagnetic scattering. For some scattering structures this matrix can be poorly conditioned. The main purpose of this study is to evaluate the efficiency of a class of incomplete LU (ILU) factorization preconditioners for solving this type of matrices. We solve the electromagnetic wave equations using the BiCG method with an ILU preconditioner in the context of a multilevel fast multipole algorithm (MLFMA). The novelty of this work is that the ILU preconditioner is constructed using the near part block diagonal submatrices generated from the MLFMA. Experimental results show that the ILU preconditioner reduces the number of BiCG iterations substantially, compared to the block diagonal preconditioner. The preconditioned iteration scheme also maintains the computational complexity of the MLFMA, and consequently reduces the...

  16. PECULIARITIES OF THE EFFECTS OF ELECTROMAGNETIC WAVES OF THE VISIBLE RANGE ON LIVING ORGANISMS

    Directory of Open Access Journals (Sweden)

    S. A. Gulyar

    2016-08-01

    Full Text Available Our experimental studies and a set of the published data allow one to conclude that animals and humans can perceive visible light not only with mediation of the visual sensory system, but also due to the existence of specific extraocular photoreceptors. In the latter system, we can classify three separate stable levels of interaction with exogeneous electromagnetic waves (EMW of the visible range. The first, most simple level is the cellular level (cells possessing sensor proteins reactable to EMW. The next, higher level is based on interaction of EVW with specialized electromagnetoreceptors; acupuncture points and meridians providing the maintenance of electromagnetic homeostasis of the organism cam be considered such a receptor system. Finally, the most complex level involves specialized sensory pathways and central brain structures controlling general homeostasis of the organism with mediation of the processes of metabolism.

  17. Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas.

    Science.gov (United States)

    Shukla, P K; Eliasson, B; Stenflo, L

    2012-07-01

    We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

  18. Theory and observations of electromagnetic ion cyclotron waves in Saturn's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.

    1993-01-01

    High-resolution Voyager 1 magnetic field observations of Saturn's inner magnetosphere are examined for the presence of ULF waves. Quasi-circular left-hand polarized transverse oscillations are found in the near-equatorial region of 5-7 Rs with a wave period about 10 s and peak amplitude of about 2 nT. The wave is identified as the electromagnetic oxygen cyclotron mode occurring at a frequency just below the O(+) ion cyclotron frequency. A theoretical model of wave excitation based on gyroresonant coupling through a temperature anisotropy of O(+) pickup ions is developed which accounts for the principal features of the wave spectrum. It is hypothesized that wave-particle interactions provide a level of scattering commensurate with the weak pitch angle diffusion regime but nonetheless one that regulates and maintains a constant thermal anisotropy of ions along the magnetic field. Arguments are also presented that O(+) was the dominant thermal ion of the Dione-Tethys plasma torus at the time of the Pioneer 11 encounter the year previous to the Voyager 1 measurements.

  19. Electromagnetic scattering of a polarized plane wave from an ellipsoidal particle in the near field

    Science.gov (United States)

    Chen, Feinan; Li, Jia

    2017-06-01

    Within the validity of the first-order Born approximation, we study the near-zone evanescent wave properties for a polarized plane wave scattering upon an ellipsoidal particle. Integral expressions are obtained for the three-dimensional electromagnetic field of the near-zone scattered evanescent wave, and the dependences of the scattered intensity distributions on the degree of polarization of the incident wave and the scattering potential profile of the particle are presented. The scattered intensity from the particle can exhibit a focused pattern concentrated around the central scattering region, but the scattered intensity generated from a circularly polarized wave shows a smooth distribution for different scattering angles. Moreover, the scattered intensity also enhances when either the summation index or the effective radius of the particle increases. Our results can be utilized to generate near-field focused scattered patterns that can be tuned flexibly by controlling the degree of the polarization of the plane wave and the scattering potential parameters of the ellipsoidal particle.

  20. Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

    Science.gov (United States)

    Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

    2018-01-01

    Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

  1. Phase spectral composition of wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

  2. Electromagnetic Properties of Multifunctional Composites Based on Glass Fiber Prepreg and Ni/Carbon Fiber Veil

    OpenAIRE

    Silveira, Daniel Consoli; Gomes, Newton; Rezende, Mirabel Cerqueira; Botelho, Edson Cocchieri

    2017-01-01

    ABSTRACT: Multifunctional composites combine structural and other physicochemical properties, with major applications in aeronautical, space, telecommunication, automotive, and medical areas. This research evaluates electromagnetic properties of multifunctional composites based on glass fiber woven fabric pre-impregnated with epoxy resin laminated together carbon fiber non-woven veil metalized with Ni. In this way, searching for possible application as radar absorbing structures or electromag...

  3. Radial wave crystals: radially periodic structures from anisotropic metamaterials for engineering acoustic or electromagnetic waves.

    Science.gov (United States)

    Torrent, Daniel; Sánchez-Dehesa, José

    2009-08-07

    We demonstrate that metamaterials with anisotropic properties can be used to develop a new class of periodic structures that has been named radial wave crystals. They can be sonic or photonic, and wave propagation along the radial directions is obtained through Bloch states like in usual sonic or photonic crystals. The band structure of the proposed structures can be tailored in a large amount to get exciting novel wave phenomena. For example, it is shown that acoustical cavities based on radial sonic crystals can be employed as passive devices for beam forming or dynamically orientated antennas for sound localization.

  4. Analysis of flexural wave propagation in poroelastic composite ...

    African Journals Online (AJOL)

    Wave propagation in an infinitely long poroelastic composite hollow cylinder in is examined by employing Biot's theory of wave propagation in poroelastic media. A poroelastic composite hollow cylinder consists of two concentric poroelastic cylindrical layers both of which are made of different poroelastic materials with each ...

  5. Electromagnetic modelling of GaAs membrane supported mm-wave receivers

    Energy Technology Data Exchange (ETDEWEB)

    Neculoiu, D [IMT Bucharest, 32B Erou Iancu Nicolae str., 72996, Bucharest (Romania); Electronics Department, POLITEHNICA University of Bucharest, 1-3 Iuliu Maniu Av., 061071 Bucharest (Romania); Muller, A [IMT Bucharest, 32B Erou Iancu Nicolae str., 72996, Bucharest (Romania); Konstantinidis, G [MRG-IESL-FORTH Heraklion, PO Box 1527, Crete (Greece)

    2006-04-01

    This paper presents a new electromagnetic modelling approach for the design of GaAs membrane supported monolithically integrated mm-wave receivers. The receivers structures are divided into membrane supported sections and bulk GaAs supported sections. Each block is modelled and designed using the full-wave electromagnetic simulation software Zeland IE3D. The Schottky diode is included in the model using the internal port feature. The design steps include the Schottky diode experimental characterization, design and measurements of membrane supported antenna demonstrators and linear/nonlinear simulations of the final receiver structures. The fabrication processes is based on GaAs micromachining. Two types of video detection receivers were designed, fabricated and tested: a 38 GHz double folded slot antenna receivers and a 45 GHz Yagi-Uda antenna receiver. Both circuits monolithically integrated the antenna with the Schottky diode on the same 2.2 {mu}m thin semiinsulating GaAs membrane. The experimental results demonstrate an isotropic voltage sensitivity of 3000 mV/mW at 38 GHz and 6000 mV/mW at 45 GHz, respectively. The measurements validate the modelling approach and open a window of opportunity for the development of innovative RF MEMS architectures operating at higher frequency, up to the sub-millimetre wave frequency range.

  6. Electromagnetic modelling of GaAs membrane supported mm-wave receivers

    Science.gov (United States)

    Neculoiu, D.; Muller, A.; Konstantinidis, G.

    2006-04-01

    This paper presents a new electromagnetic modelling approach for the design of GaAs membrane supported monolithically integrated mm-wave receivers. The receivers structures are divided into membrane supported sections and bulk GaAs supported sections. Each block is modelled and designed using the full-wave electromagnetic simulation software Zeland IE3D. The Schottky diode is included in the model using the internal port feature. The design steps include the Schottky diode experimental characterization, design and measurements of membrane supported antenna demonstrators and linear/nonlinear simulations of the final receiver structures. The fabrication processes is based on GaAs micromachining. Two types of video detection receivers were designed, fabricated and tested: a 38 GHz double folded slot antenna receivers and a 45 GHz Yagi-Uda antenna receiver. Both circuits monolithically integrated the antenna with the Schottky diode on the same 2.2 µm thin semiinsulating GaAs membrane. The experimental results demonstrate an isotropic voltage sensitivity of 3000 mV/mW at 38 GHz and 6000 mV/mW at 45 GHz, respectively. The measurements validate the modelling approach and open a window of opportunity for the development of innovative RF MEMS architectures operating at higher frequency, up to the sub-millimetre wave frequency range.

  7. Probing extra dimension through gravitational wave observations of compact binaries and their electromagnetic counterparts

    CERN Document Server

    Yu, Hao; Huang, Fa Peng; Wang, Yong-Qiang; Meng, Xin-He; Liu, Yu-Xiao

    2016-01-01

    The gravitational wave (GW) observations of compact binaries and their possible electromagnetic counterparts may be used to probe the nature of the extra dimension. It is widely accepted that gravitons and photons are the only two completely confirmed objects that can travel along the null geodesics in our four-dimensional space-time. But when one considers that there exists the fifth dimension and only the GW can propagate freely in the bulk, the causal propagations of the GW and electromagnetic wave (EMW) are in general different. In this paper, we compute the null geodesics of the GW and EMW in a five-dimensional anti-de Sitter space-time and our four-dimensional universe in the present of the curvature of universe $k$, respectively. We show that for general cases the horizon radius of the GW is longer than the EMW within the equal time. Taking the GW 150914 event detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and the X-ray event detected by the Fermi Gamma-ray Burst Mo...

  8. Atomic layer lithography of wafer-scale nanogap arrays for extreme confinement of electromagnetic waves.

    Science.gov (United States)

    Chen, Xiaoshu; Park, Hyeong-Ryeol; Pelton, Matthew; Piao, Xianji; Lindquist, Nathan C; Im, Hyungsoon; Kim, Yun Jung; Ahn, Jae Sung; Ahn, Kwang Jun; Park, Namkyoo; Kim, Dai-Sik; Oh, Sang-Hyun

    2013-01-01

    Squeezing light through nanometre-wide gaps in metals can lead to extreme field enhancements, nonlocal electromagnetic effects and light-induced electron tunnelling. This intriguing regime, however, has not been readily accessible to experimentalists because of the lack of reliable technology to fabricate uniform nanogaps with atomic-scale resolution and high throughput. Here we introduce a new patterning technology based on atomic layer deposition and simple adhesive-tape-based planarization. Using this method, we create vertically oriented gaps in opaque metal films along the entire contour of a millimetre-sized pattern, with gap widths as narrow as 9.9 Å, and pack 150,000 such devices on a 4-inch wafer. Electromagnetic waves pass exclusively through the nanogaps, enabling background-free transmission measurements. We observe resonant transmission of near-infrared waves through 1.1-nm-wide gaps (λ/1,295) and measure an effective refractive index of 17.8. We also observe resonant transmission of millimetre waves through 1.1-nm-wide gaps (λ/4,000,000) and infer an unprecedented field enhancement factor of 25,000.

  9. Electromagnetic wave propagation through a dielectric-chiral interface and through a chiral slab

    Science.gov (United States)

    Bassiri, S.; Papas, C. H.; Engheta, N.

    1988-01-01

    The reflection from and transmission through a semiinfinite chiral medium are analyzed by obtaining the Fresnel equations in terms of parallel- and perpendicular-polarized modes, and a comparison is made with results reported previously. The chiral medium is described electromagnetically by the constitutive relations D = (epsilon)E+i(gamma)B and H = i(gamma)E+(1/mu)B. The constants epsilon, mu and gamma are real and have values that are fixed by the size, the shape, and the spatial distribution of the elements that collectively compose the medium. The conditions are obtained for the total internal reflection of the incident wave from the interface and for the existence of the Brewster angle. The effects of the chirality on the polarization and the intensity of the reflected wave from the chiral half-space are discussed and illustrated by using the Stokes parameters. The propagation of electromagnetic wave through an infinite slab of chiral medium is formulated for oblique incidence and solved analytically for the case of normal incidence.

  10. Kinetic Jeans instability and nonlinear damping of electromagnetic waves in self gravitating dusty plasma

    Science.gov (United States)

    Rozina, Ch.; Tsintsadze, N. L.; Madiha, M.; Zeba, I.

    2017-05-01

    A kinetic theory of the Jeans instability of a self gravitating dusty plasma has been developed in the presence of nonlinear Landau damping (NLD) term. We demonstrate that NLD alters the growth rate of the gravitational collapse of the gravitating dusty plasma. The dispersion relation of modified Jeans instability is obtained and analyzed for specific conditions. Jeans frequency is compared with the dust acoustic frequency; new definition of Jeans wave length is introduced. The maximum growth rate is obtained for a particular condition as well as the Jeans critical mass is defined. Next to address the heating of plasma through radiation processes, we investigate the nonlinear theory of high frequency electromagnetic waves (EMWs) in a collisionless dusty plasma by using a set of Vlasov-Poisson equations. The effects of the nonlocal nonlinear Landau term (appearing due to the nonlinear interaction of EMWs with gravitating dusty plasma) in the nonlinear Schrödinger equation are examined. It is found that nonlinear Landau damping of EMWs leads to transfer of effective energy to the plasma particles, the corresponding decay rate of EMWs appears to be a function of amplitude of electromagnetic pump waves, and damping can be faster in the presence of large ion number density.

  11. Constraining the Composition of the Earth from Long-period Electromagnetic Sounding of the Lower Mantle

    DEFF Research Database (Denmark)

    Khan, A.; Connolly, J.; Olsen, Nils

    We reexamine the problem of inverting global transfer functions to constrain the internal structure of the Earth. We go beyond the conventional approach of inverting electromagnetic induction data by inverting directly for chemical composition and thermal state, using the model system Ca...... measurements to estimate the bulk lunar electrical conductivity structure from which transfer functions are calculated. To further constrain the radial density profile in the inversion we added constraints imposed by mass and moment of inertia. Our results indicate that electromagnetic sounding...

  12. Wave fields in real media wave propagation in anisotropic, anelastic, porous and electromagnetic media

    CERN Document Server

    Carcione, José M

    2007-01-01

    This book examines the differences between an ideal and a real description of wave propagation, where ideal means an elastic (lossless), isotropic and single-phase medium, and real means an anelastic, anisotropic and multi-phase medium. The analysis starts by introducing the relevant stress-strain relation. This relation and the equations of momentum conservation are combined to give the equation of motion. The differential formulation is written in terms of memory variables, and Biot's theory is used to describe wave propagation in porous media. For each rheology, a plane-wave analysis is performed in order to understand the physics of wave propagation. The book contains a review of the main direct numerical methods for solving the equation of motion in the time and space domains. The emphasis is on geophysical applications for seismic exploration, but researchers in the fields of earthquake seismology, rock acoustics, and material science - including many branches of acoustics of fluids and solids - may als...

  13. A kilonova as the electromagnetic counterpart to a gravitational-wave source

    Science.gov (United States)

    Smartt, S. J.; Chen, T.-W.; Jerkstrand, A.; Coughlin, M.; Kankare, E.; Sim, S. A.; Fraser, M.; Inserra, C.; Maguire, K.; Chambers, K. C.; Huber, M. E.; Krühler, T.; Leloudas, G.; Magee, M.; Shingles, L. J.; Smith, K. W.; Young, D. R.; Tonry, J.; Kotak, R.; Gal-Yam, A.; Lyman, J. D.; Homan, D. S.; Agliozzo, C.; Anderson, J. P.; Angus, C. R.; Ashall, C.; Barbarino, C.; Bauer, F. E.; Berton, M.; Botticella, M. T.; Bulla, M.; Bulger, J.; Cannizzaro, G.; Cano, Z.; Cartier, R.; Cikota, A.; Clark, P.; De Cia, A.; Della Valle, M.; Denneau, L.; Dennefeld, M.; Dessart, L.; Dimitriadis, G.; Elias-Rosa, N.; Firth, R. E.; Flewelling, H.; Flörs, A.; Franckowiak, A.; Frohmaier, C.; Galbany, L.; González-Gaitán, S.; Greiner, J.; Gromadzki, M.; Guelbenzu, A. Nicuesa; Gutiérrez, C. P.; Hamanowicz, A.; Hanlon, L.; Harmanen, J.; Heintz, K. E.; Heinze, A.; Hernandez, M.-S.; Hodgkin, S. T.; Hook, I. M.; Izzo, L.; James, P. A.; Jonker, P. G.; Kerzendorf, W. E.; Klose, S.; Kostrzewa-Rutkowska, Z.; Kowalski, M.; Kromer, M.; Kuncarayakti, H.; Lawrence, A.; Lowe, T. B.; Magnier, E. A.; Manulis, I.; Martin-Carrillo, A.; Mattila, S.; McBrien, O.; Müller, A.; Nordin, J.; O’Neill, D.; Onori, F.; Palmerio, J. T.; Pastorello, A.; Patat, F.; Pignata, G.; Podsiadlowski, Ph.; Pumo, M. L.; Prentice, S. J.; Rau, A.; Razza, A.; Rest, A.; Reynolds, T.; Roy, R.; Ruiter, A. J.; Rybicki, K. A.; Salmon, L.; Schady, P.; Schultz, A. S. B.; Schweyer, T.; Seitenzahl, I. R.; Smith, M.; Sollerman, J.; Stalder, B.; Stubbs, C. W.; Sullivan, M.; Szegedi, H.; Taddia, F.; Taubenberger, S.; Terreran, G.; van Soelen, B.; Vos, J.; Wainscoat, R. J.; Walton, N. A.; Waters, C.; Weiland, H.; Willman, M.; Wiseman, P.; Wright, D. E.; Wyrzykowski, Ł.; Yaron, O.

    2017-11-01

    Gravitational waves were discovered with the detection of binary black-hole mergers and they should also be detectable from lower-mass neutron-star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal. This signal is luminous at optical and infrared wavelengths and is called a kilonova. The gravitational-wave source GW170817 arose from a binary neutron-star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC 4993, which is spatially coincident with GW170817 and with a weak, short γ-ray burst. The transient has physical parameters that broadly match the theoretical predictions of blue kilonovae from neutron-star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 ± 0.01 solar masses, with an opacity of less than 0.5 square centimetres per gram, at a velocity of 0.2 ± 0.1 times light speed. The power source is constrained to have a power-law slope of ‑1.2 ± 0.3, consistent with radioactive powering from r-process nuclides. (The r-process is a series of neutron capture reactions that synthesise many of the elements heavier than iron.) We identify line features in the spectra that are consistent with light r-process elements (atomic masses of 90–140). As it fades, the transient rapidly becomes red, and a higher-opacity, lanthanide-rich ejecta component may contribute to the emission. This indicates that neutron-star mergers produce gravitational waves and radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.

  14. The method of impedance transformation for electromagnetic waves propagating in one-dimension plasma photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jingfeng; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Gao, Ruilin; Jia, Jieshu; Wang, Ying; Zhou, Zhongxiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Wang, Xiaoou [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Wu, Jian [National Key Laboratory of Electromagnetic Environment (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China); Li, Hui [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory of Electromagnetic Environment (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China)

    2016-08-15

    This study focuses on the transmission of normal-incidence electromagnetic waves in one-dimensional plasma photonic crystals. Using the Maxwell's equations in a medium, a method that is based on the concept of impendence is employed to perform the simulation. The accuracy of the method was evaluated by simulating a one-layer plasma and conventional photonic crystal. In frequency-domain, the transmission and reflection coefficients in the unmagnetized plasma photonic crystal were calculated, and the influence factors on plasma photonic crystals including dielectric constants of dielectric, spatial period, filling factor, plasma frequency, and collision frequency were studied.

  15. Model of the electromagnetic waves processing in ultrasound; Modelo de procesamiento de ondas electromagneticas en ultrasonido

    Energy Technology Data Exchange (ETDEWEB)

    Abrego L, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Azorin N, J. [UAM-I, 09340 Mexico D.F. (Mexico); Siles A, S. [CICATA, IPN, 07000 Mexico D.F. (Mexico); Cruz O, A. [CINVESTAV, IPN, 07000 Mexico D.F. (Mexico)

    2004-07-01

    In this work, a model to process the electromagnetic waves in ultrasonic equipment is proposed and it is experimentally demonstrated that, the origin of the ultrasound is electronic and non mechanic. The above mentioned, it has been demonstrated when making in an electronic equipment a spectral analysis the one that indicated an unfolding of the original ultrasonic pulses of 17 K Hz., to 88 K Hz., and of 5 MHz., to 23 GHz. Also, it was obtained the degradation with ultrasound of particles of Hematite and of Galena, as well as the fading of the methylene blue and the generation of an electric current exciting with ultrasound. (Author)

  16. Reflection and transmission of electromagnetic waves at a temporal boundary: comment.

    Science.gov (United States)

    Bakunov, M I; Maslov, A V

    2014-10-15

    Recently, Xiao et al. [Opt. Lett. 39, 574 (2014)] compared two sets of boundary conditions and the resulting transformation coefficients for an electromagnetic wave at a temporal boundary. They claimed to identify a correct set and to resolve the existing discrepancy in the literature. We point out that the boundary conditions discarded by Xiao et al. as incorrect have been used in the literature for rapidly growing plasma, for which the material model of Xiao et al. is not appropriate. We show that Xiao et al. misinterpreted the results from the literature by opposing two sets of boundary conditions that are related to different material models of the temporal boundary.

  17. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Aldrigo, Martino; Costanzo, Alessandra [Department of Electrical, Electronic, and Information Engineering “Guglielmo Marconi” – DEI, University of Bologna, Viale del Risorgimento, 2, 40132 Bologna (Italy); Dragoman, Mircea [National Institute for Research and Development in Microtechnology (IMT), P.O. Box 38-160, 023573 Bucharest (Romania); Dragoman, Daniela [Department of Physics, University of Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania)

    2013-11-14

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  18. Spectrum of an electromagnetic light wave on scattering from an anisotropic semisoft boundary medium.

    Science.gov (United States)

    Wang, Tao; Jiang, Zhenfei; Ji, Xiaoling; Zhao, Daomu

    2016-04-01

    Spectral shifts and spectral switches of a polychromatic electromagnetic light wave on scattering from an anisotropic semisoft boundary medium are discussed. It is shown that both the property of the incident field and the character of the scattering medium play roles in the change of the spectrum of the far-zone scattered field. It is also shown that the distribution of the far-zone scattered spectrum, including the magnitude of the spectral shift and the direction at which the spectral switch occurs, is rotationally nonsymmetric.

  19. Scattering of electromagnetic waves from a periodic surface with random roughness

    Science.gov (United States)

    Yueh, H. A.; Shin, R. T.; Kong, J. A.

    1988-01-01

    Equations for the scattering of electromagnetic waves from a randomly perturbed periodic surface have been formulated using the extended boundary condition method and solved using the small perturbation method. Surface currents and scattered fields are solved for up to the second order. The results indicate that as the correlation length of the random roughness increases, the bistatic scattering patterns of the scattered fields show several beams associated with each Bragg diffraction direction of the periodic surface. The beam shape becomes broader with smaller correlation length. Results obtained using the Kirchhoff approximation are found to agree well with the present results for the hh and vv polarized backscattering coefficients for small angles of incidence.

  20. Survey of low-frequency electromagnetic waves stimulated by two coexisting newborn ion species

    Science.gov (United States)

    Brinca, Armando L.; Tsurutani, Bruce T.

    1988-01-01

    Parallel electromagnetic instabilities generated by coexisting newborn hydrogen and oxygen ions are studied for different orientations of the interplanetary magnetic field with respect to the solar wind velocity. The wave growth dependence on the densities and temperatures of the newborn species is investigated. The results indicate that in most domains of the Brillouin plane each ion beam can excite resonant instabilities without undue influence from the other newborn ion species. Although comparable resonant instabilities are more efficiently generated by the lighter newborn ions in ion-rich environments, the growth stimulated by the heavier species can withstand large beam density decreases.

  1. Unconditionally stable WLP-FDTD method for the modeling of electromagnetic wave propagation in gyrotropic materials.

    Science.gov (United States)

    Li, Zheng-Wei; Xi, Xiao-Li; Zhang, Jin-Sheng; Liu, Jiang-fan

    2015-12-14

    The unconditional stable finite-difference time-domain (FDTD) method based on field expansion with weighted Laguerre polynomials (WLPs) is applied to model electromagnetic wave propagation in gyrotropic materials. The conventional Yee cell is modified to have the tightly coupled current density components located at the same spatial position. The perfectly matched layer (PML) is formulated in a stretched-coordinate (SC) system with the complex-frequency-shifted (CFS) factor to achieve good absorption performance. Numerical examples are shown to validate the accuracy and efficiency of the proposed method.

  2. Analytical solutions of electromagnetic waves in focusing and magnifying cylindrical hyperlenses: Green's function approach.

    Science.gov (United States)

    Tapsanit, Piyawath; Yamashita, Masatsugu; Otani, Chiko

    2014-01-13

    The analytical solutions of the electromagnetic waves in the inhomogeneous cylindrical hyperlens (CH) comprising concentric cylindrical layers (CCLs) with multiple point sources located either outside the structure in the focusing process or inside the core in the magnifying process are obtained by means of Green's function analysis. The solutions are consistent with FDTD simulation in both processes. The sub-wavelength focal spot λ/16.26 from two point sources with wavelength 465 nm is demonstrated in the CH made by alternating silver and silica CCLs. Our solutions are expected to be the efficient tools for designing the sub-wavelength focusing and imaging cylindrical hyperlens.

  3. Analysis of the electromagnetic wave resistivity tool in deviated well drilling

    Science.gov (United States)

    Zhang, Yumei; Xu, Lijun; Cao, Zhang

    2014-04-01

    Electromagnetic wave resistivity (EWR) tools are used to provide real-time measurements of resistivity in the formation around the tool in Logging While Drilling (LWD). In this paper, the acquired resistivity information in the formation is analyzed to extract more information, including dipping angle and azimuth direction of the drill. A finite element (FM) model of EWR tool working in layered earth formations is established. Numerical analysis and FM simulations are employed to analyze the amplitude ratio and phase difference between the voltages measured at the two receivers of the EWR tool in deviated well drilling.

  4. Singular polarimetry: evolution of polarization singularities in electromagnetic waves propagating in a weakly anisotropic medium.

    Science.gov (United States)

    Bliokh, Konstantin Yu; Niv, Avi; Kleiner, Vladimir; Hasman, Erez

    2008-01-21

    We describe the evolution of a paraxial electromagnetic wave characterizing by a non-uniform polarization distribution with singularities and propagating in a weakly anisotropic medium. Our approach is based on the Stokes vector evolution equation applied to a non-uniform initial polarization field. In the case of a homogeneous medium, this equation is integrated analytically. This yields a 3-dimensional distribution of the polarization parameters containing singularities, i.e. C-lines of circular polarization and L-surfaces of linear polarization. The general theory is applied to specific examples of the unfolding of a vectorial vortex in birefringent and dichroic media.

  5. Attenuation characteristics of electromagnetic waves in a weak collisional and fully ionized dusty plasma

    Science.gov (United States)

    Dan, Li; Guo, Li-Xin; Li, Jiang-Ting; Chen, Wei; Yan, Xu; Huang, Qing-Qing

    2017-09-01

    The expression of complex dielectric permittivity for non-magnetized fully ionized dusty plasma is obtained based on the kinetic equation in the Fokker-Planck-Landau collision model and the charging equation of the statistical theory. The influences of density, average size of dust grains, and balanced charging of the charge number of dust particles on the attenuation properties of electromagnetic waves in fully ionized dusty plasma are investigated by calculating the attenuation constant. In addition, the attenuation characteristics of weakly ionized and fully ionized dusty plasmas are compared. Results enriched the physical mechanisms of microwave attenuation for fully ionized dusty plasma and provide a theoretical basis for future studies.

  6. Effect of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    Science.gov (United States)

    Gamayunov, K. V.; Khazanov, G. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  7. Anderson localization of electromagnetic waves in randomly-stratified magnetodielectric media with uniform impedance.

    Science.gov (United States)

    Kim, Kihong

    2015-06-01

    The propagation and the Anderson localization of electromagnetic waves in a randomly-stratified slab, where both the dielectric permittivity and the magnetic permeability depend on one spatial coordinate in a random manner, is theoretically studied. The case where the wave impedance is uniform, while the refractive index is random, is considered in detail. The localization length and the disorder-averaged transmittance of s and p waves incident obliquely on the slab are calculated as a function of the incident angle θ and the strength of randomness in a numerically precise manner, using the invariant imbedding method. It is found that the waves incident perpendicularly on the slab are delocalized, while those incident obliquely are localized. As the incident angle increases from zero, the localization length decreases from infinity monotonically to some finite value. The localization length is found to depend on the incident angle as θ-4 and a simple analytical formula, which works quite well for weak disorder and small incident angles, is derived. The localization length does not depend on the wave polarization, but the disorder-averaged transmittance generally does.

  8. Electromagnetic waves with frequencies near the local proton gyrofrequency: ISEE-3 1 AU observations

    Science.gov (United States)

    Tsurutani, Bruce T.; Arballo, John K.; Mok, John; Smith, Edward J.; Mason, Glenn M.; Tan, Lun C.

    1994-01-01

    Low Frequency (LF) electromagnetic waves with periods near the local proton gyrofrequency have been detected in interplanetary space by the magnetometer onboard International-Sun-Earth-Explorer-3 (ISEE-3). Transverse peak-to-peak amplitudes as large as delta vector B/absolute value of B approximately 0.4 have been noted with compressional components (Delta absolute value of B/absolute value of B) typically less than or = 0.1. Generally, the waves have even smaller amplitudes, or are not detectable within the solar wind turbulence. The waves are elliptically/linearly polarized and are often, but not always, found to propagate nearly along vector B(sub zero). Both right- and left-hand polarizations in the spacecraft-frame have been detected. The waves are observed during all orientations of the interplanetary magnetic field, with the Parker spiral orientation being the most common case. Because the waves are detected at and near the local proton cyclotron frequency, the generation mechanism must almost certainly be solar wind pickup of freshly created hydrogen ions. Possible sources for the hydrogen are the Earth's atmosphere, coronal mass ejections from the Sun, comets and interstellar neutral atoms. At this time it is not obvious which potential source is the correct one. Statistical tests employing over one year of ISEE-3 data will be done in the near future to eliminate/confirm some of these possibilities.

  9. Development and performance evaluation of an electromagnetic-type shock wave generator for lipolysis.

    Science.gov (United States)

    Liang, S M; Chang, M H; Yang, Z Y

    2014-01-01

    This study aims at the design and development of electromagnetic-type intermittent shock wave generation in a liquid. The shock wave generated is focused at a focal point through an acoustic lens. This hardware device mainly consists of a full-wave bridge rectifier, 6 capacitors, a spark gap, and a flat coil. A metal disk is mounted in a liquid-filled tube and is placed in close proximity to the flat coil. Due to the repulsive force existing between the coil and disk shock waves are generated, while an eddy current is induced in the metal disk. Some components and materials associated with the device are also described. By increasing the capacitance content to enhance electric energy level, a highly focused pressure can be achieved at the focal point through an acoustic lens in order to lyse fat tissue. Focused pressures were measured at the focal point and its vicinity for different operation voltages. The designed shock wave generator with an energy intensity of 0.0016 mJ/mm(2) (at 4 kV) and 2000 firings or higher energy intensities with 1000 firings is found to be able to disrupt pig fat tissue.

  10. Generation of electromagnetic ion cyclotron waves in the near-Earth magnetotail during dipolarization: two-dimensional global hybrid simulation

    Science.gov (United States)

    Guo, Zhifang; Wu, Mingyu; Du, Amin

    2017-04-01

    We employ two-dimensional global hybrid simulations to study the generation, propagation and polarization of electromagnetic ion cyclotron (EMIC) waves in the near-Earth magnetotail during dipolarization. In our simulation, EMIC waves with left-hand polarized signals originate in the low-latitude magnetotail as a result of the ion temperature anisotropy which is due to ion heating by Alfvén waves. Subsequently, EMIC waves can propagate along the ambient magnetic field toward high-latitudes. Our work provides one possible mechanism for the generation of EMIC waves observed in the near-Earth magnetotail.

  11. Double-layer Electromagnetic Wave Absorber Based on Carbon Nanotubes Doped with La(NO33 and Fe3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Cuiling HOU

    2017-08-01

    Full Text Available Double-layer structure absorbing materials based on the impedance matching principle and transmission line theory can effectively improve the electromagnetic wave absorbing properties. In this paper, the electro-magnetic wave absorbing properties of double-layer absorbers (2 mm thickness, where multiwall carbon nanotube (MWCNT-La(NO33/polyvinyl chloride (PVC and MWCNT-Fe3O4/PVC composites had been taken turns as the absorption layer and matching layer, were investigated in 2 – 18 GHz range. The absorbing properties of single- and double-layer structure and different each-layer thickness with two types of combinations were compared. The results showed that the design of double-layer structure for composites could effectively broaden the absorption frequency area, and increase the absorption intensity. When MWCNT-La(NO33/PVC composite were used as absorption layers with 0.6 mm thickness, the absorption bandwidth (< – 15 dB or > 97 % of double-layer composite was the widest, reaching a maximum of about 3.36 GHz, and the absorption peak value was also the lowest about – 46.02 dB at 16.24 GHz.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16279

  12. Linear phased array of piezoelectric transducers for delamination monitoring in a composite laminate using Lamb waves

    Science.gov (United States)

    Rathod, Vivek T.; Chakraborty, Nibir; Roy Mahapatra, D.

    2011-04-01

    Applications of Linear Phased array concept have been extended from electromagnetic antennae to many other areas due to their capability to direct, magnify and pick up energy in and from desired directions. Apart from radar, optics and medical imaging, one such growing area is in the non-destructive testing of structures. The extensive use of linear array can be attributed to the attenuation of the waves generated in the structure due to inherent damping and loss in the materials and discontinuities. Linear phased arrays are used as actuator in ultrasonic imaging and diagnostics to magnify the energy at a given direction or point in the structure. In the present work the property of amplifying the wave generated in a particular direction is exploited and is studied on a carbon composite structure. Almost all of the existing imaging methods in context of phased array are based on through thickness and bulk wave modes. In the present research we employ Lamb wave which propagates in a doubly bounded media like structural panels. The spreading of energy in a composite laminate is studied in the form of lobe patterns obtained using amplitude of symmetric Lamb wave mode (S0) with a particular orientation of the linear array with fiber direction. The effect of damage in the form of a delamination in a CFRP composite plate on the lobe pattern is analyzed.

  13. Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

    Science.gov (United States)

    Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

    1994-01-01

    We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

  14. Electromagnetism

    CERN Document Server

    Grant, Ian S

    1990-01-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw the Physics of Stars Second Edition A. C. Phillips Computing for Scient

  15. Kinetic effects during the interaction between high density microplasma and electromagnetic wave

    Science.gov (United States)

    Levko, Dmytro; Raja, Laxminarayan

    2017-10-01

    The interaction between a high-density microplasma and high-power electromagnetic wave is studied by one-dimensional Particle-in-Cell Monte Carlo collisions model coupled with the Maxwell's equations. We find the value of the amplitude of the wave field above which a fully ionized plasma is generated on the picosecond time scale. This fully ionized plasma is obtained only in the skin layer while the ionization degree of the plasma bulk is 20%. The simulation results show that such non-homogeneous distribution of plasma and gas density influences significantly the heating of plasma electrons and time evolution of the electron energy probability function. Air Force Office of Scientific Research (AFOSR) through a Multi-University Research Initiative (MURI) Grant titled ``Plasma-Based Reconfigurable Photonic Crystals and Metamaterials'' with Dr. Mitat Birkan as the program manager.

  16. Analog electromagnetically induced transparency for circularly polarized wave using three-dimensional chiral metamaterials.

    Science.gov (United States)

    Lin, Hai; Yang, Dong; Han, Song; Liu, Yangjie; Yang, Helin

    2016-12-26

    In this paper, we theoretically and experimentally demonstrate a three-dimensional metamaterial that can motivate electromagnetic induced transparency (EIT) by using circular polarized wave as stimulations. The unit cell consists of a pair of metallic strips printed on both sides of the printed circuit board (PCB), where a conductive cylinder junction is used to connect the metal strips by drilling a hole inside the substrate. When a right circularly polarized wave is incident, destructive interference is excited between meta-atoms of the 3D structure, the transmission spectrum demonstrates a sharp transparency window. A coupled oscillator model and an electrical equivalent circuit model are applied to quantitatively and qualitatively analyze the coupling mechanism in the EIT-like metamaterial. Analysis in detail shows the EIT window's amplitude and frequency are modulated by changing the degree of symmetry breaking. The proposed metamaterial may achieve potential applications in developing chiral slow light devices.

  17. Analog electromagnetically induced transparency for circularly polarized wave using three dimensional chiral metamaterials

    CERN Document Server

    Lin, Hai; Han, Song; Liu, Yangjie; Yang, Helin

    2016-01-01

    In this paper, we theoretically and experimentally demonstrate a three dimensional metamaterial that can motivate electromagnetic induced transparency (EIT) by using circular polarized wave as stimulations. The unit cell consists of a pair of metallic strips printed on both sides of the printed circuit board (PCB), where a conductive cylinder junction is used to connect the metal strips by drilling a hole inside the substrate. When a right circularly polarized wave is incident, destructive interference is excited between meta-atoms of the 3D structure, the transmission spectrum demonstrates a sharp transparency window. A coupled oscillator model and an electrical equivalent circuit model are applied to quantitatively and qualitatively analyze the coupling mechanism in the EIT-like metamaterial. Analysis in detail shows the EIT window's amplitude and frequency are modulated by changing the degree of symmetry breaking. The proposed metamaterial may achieve potential applications in developing chiral slow light ...

  18. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering

    Science.gov (United States)

    Zhu, P. Y.; Fung, A. K.

    1986-01-01

    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  19. Fokker-Planck electron diffusion caused by an obliquely propagating electromagnetic wave packet of narrow bandwidth

    Science.gov (United States)

    Hizanidis, Kyriakos

    1989-01-01

    The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.

  20. Propagation of electromagnetic waves in stratified media with nonlinearity in both dielectric and magnetic responses.

    Science.gov (United States)

    Kim, Kihong; Phung, D K; Rotermund, F; Lim, H

    2008-01-21

    We develop a generalized version of the invariant imbedding method, which allows us to solve the electromagnetic wave equations in arbitrarily inhomogeneous stratified media where both the dielectric permittivity and magnetic permeability depend on the strengths of the electric and magnetic fields, in a numerically accurate and efficient manner. We apply our method to a uniform nonlinear slab and find that in the presence of strong external radiation, an initially uniform medium of positive refractive index can spontaneously change into a highly inhomogeneous medium where regions of positive or negative refractive index as well as metallic regions appear. We also study the wave transmission properties of periodic nonlinear media and the influence of nonlinearity on the mode conversion phenomena in inhomogeneous plasmas. We argue that our theory is very useful in the study of the optical properties of a variety of nonlinear media including nonlinear negative index media fabricated using wires and split-ring resonators.

  1. Unusual characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies

    Science.gov (United States)

    Brinca, A. L.; Tsurutani, B. T.

    1987-01-01

    The characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies are examined using a model of solar wind permeated by dilute drifting ring distributions of electrons and oxygen ions with finite thermal spreads. The model has parameters compatible with the ICE observations at the Giacobini-Zinner comet. It is shown that cometary newborn ions with large perpendicular energies can excite a wave mode with rest frame frequencies in the order of the heavy ion cyclotron frequency, Omega(i), and unusual propagation characteristics at small obliquity angles. For parallel propagation, the mode is left-hand circularly polarized, might be unstable in a frequency range containing Omega(i), and moves in the direction of the newborn ion drift along the static magnetic field.

  2. Diffraction of electromagnetic waves by a two-dimensional periodic waveguide-dielectric array

    Science.gov (United States)

    Krekhtunov, V. M.; Tiulin, V. A.

    1983-02-01

    An analysis is presented of electromagnetic-wave diffraction by a two-dimensional periodic waveguide array covered by several layers of an inhomogeneous dielectric. For the case of quasi-periodic excitation of the array, the solution is obtained by the method of projection field matching in planes of junctions of longitudinally homogeneous regions. An orthonormal system of eigenvector functions of the transversely inhomogeneous Floquet channel is used as the basis in the two-dimensional periodic dielectric structure. The effectiveness of the proposed algorithm is demonstrated by a calculation of the coefficient of reflection of an incident wave from the aperture of an array of circular waveguides, matched with free space via stepwise dielectric rods. It is shown that the use of stepwise dielectric rods for the matching of waveguide antenna arrays is more effective than the use of dielectric cylinders jutting from the waveguides.

  3. Prediction and measurement of the electromagnetic environment of high-power medium-wave and short-wave broadcast antennas in far field.

    Science.gov (United States)

    Tang, Zhanghong; Wang, Qun; Ji, Zhijiang; Shi, Meiwu; Hou, Guoyan; Tan, Danjun; Wang, Pengqi; Qiu, Xianbo

    2014-12-01

    With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3-1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Electromagnetic wave attenuation measurements in a ring-shaped inductively coupled air plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolong, Wei; Haojun, Xu; Min, Lin; Chen, Su [Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi' an 710038 (China); Jianhai, Li [Institute of Aerospace Engineering, Air Force Engineering University, Xi' an 710038 (China)

    2015-05-28

    An aerocraft with the surface, inlet and radome covered large-area inductive coupled plasma (ICP) can attenuate its radar echo effectively. The shape, thickness, and electron density (N{sub e}) distribution of ICP are critical to electromagnetic wave attenuation. In the paper, an air all-quartz ICP generator in size of 20 × 20 × 7 cm{sup 3} without magnetic confinement is designed. The discharge results show that the ICP is amorphous in E-mode and ring-shaped in H-mode. The structure of ICP stratifies into core region and edge halo in H-mode, and its width and thickness changes from power and pressure. Such phenomena are explained by the distribution of RF magnetic field, the diffusion of negative ions plasma and the variation of skin depth. In addition, the theoretical analysis shows that the N{sub e} achieves nearly uniform within the electronegative core and sharply steepens in the edge. The N{sub e} of core region is diagnosed by microwave interferometer under varied conditions (pressure in range of 10–50 Pa, power in 300–700 W). Furthermore, the electromagnetic wave attenuation measurements were carried out with the air ICP in the frequencies of 4–5 GHz. The results show that the interspaced ICP is still effective to wave attenuation, and the wave attenuation increases with the power and pressure. The measured attenuation is approximately in accordance with the calculation data of finite-different time-domain simulations.

  5. Effect of hot injections on electromagnetic ion-cyclotron waves in inner magnetosphere of Saturn

    Science.gov (United States)

    Kumari, Jyoti; Kaur, Rajbir; Pandey, R. S.

    2018-02-01

    Encounter of Voyager with Saturn's environment revealed the presence of electromagnetic ion-cyclotron waves (EMIC) in Saturnian magnetosphere. Cassini provided the evidence of dynamic particle injections in inner magnetosphere of Saturn. Also inner magnetosphere of Saturn has highest rotational flow shear as compared to any other planet in our solar system. Hence during these injections, electrons and ions are transported to regions of stronger magnetic field, thus gaining energy. The dynamics of the inner magnetosphere of Saturn are governed by wave-particle interaction. In present paper we have investigated those EMIC waves pertaining in background plasma which propagates obliquely with respect to the magnetic field of Saturn. Applying kinetic approach, the expression for dispersion relation and growth rate has been derived. Magnetic field model has been used to incorporate magnetic field strength at different latitudes for radial distance of 6.18 R_{{s}} (1 R_{{s}}= 60{,}268 km). Various parameters affecting the growth of EMIC waves in cold bi-Maxwellian background and after the hot injections has been studied. Parametric analysis inferred that after hot injections, growth rate of EMIC waves increases till 10° and decreases eventually with increase in latitude due to ion density distribution in near-equatorial region. Also, growth rate of EMIC waves increases with increasing value of temperature anisotropy and AC frequency, but the growth rate decreases as the angle of propagation with respect to B0 (Magnetic field at equator) increases. The injection events which assume the Loss-cone distribution of particles, affect the lower wave numbers of the spectra.

  6. Electromagnetic Waves Dispersion and Interaction of an Annular Beam-Ion Channel System in Plasma Waveguide

    Directory of Open Access Journals (Sweden)

    Jixiong Xiao

    2017-01-01

    Full Text Available A linear theory for the electromagnetic properties and interactions of an annular beam-ion channel system in plasma waveguide is presented. The dispersion relations for two families of propagating modes, including the electrostatic and transverse magnetic modes, are derived. The dependencies of the dispersion behavior and interaction for different wave modes on the thickness of the annular beam and betatron oscillation frequency are studied in detail by numerical calculations. The results show that the inner and outer radii of the beam have different influences on propagation properties of the electrostatic and electromagnetic modes with different betatron oscillation parameters. In the weak ion channel situation, the two types of electrostatic waves, that is, space charge and betatron modes, have no interaction with the transverse magnetic modes. However, in the strong ion channel situation, the transverse magnetic modes will have two branches and a low frequency mode emerged as the new branch. In this case, compared with the solid beam case, the betatron modes not only can interact with the high frequency branch at small wavenumber but also can interact with the low frequency branch at large wavenumber.

  7. Reflection and Transmission of Plane Electromagnetic Waves by a Geologic Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Aldridge, David F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-04-01

    Electric field and magnetic field reflection and transmission responses generated by a plane wave normally incident onto a finite - thickness geologic layer are mathematically derived and numerically evaluated. A thin layer with enhanced electric current conductivity and/or magnetic permeability is a reasonable geophysical representation of a hydraulic fracture inject ed with a high - contrast proppant pack. Both theory and numerics indicate that backward - and forward - scattered electromagnetic wavefields are potentially observable in a field experiment, despite the extreme thinness of a fracture compared to a typical low - frequency electromagnetic wavelength. The First Born Approximation (FBA) representation of layer scattering, significant for inversion studies, is shown to be accurate for a thin layer with mild medium parameter (i.e., conductivity, permeability, and per mittivity) contrasts with the surrounding homogeneous wholespace. However, FBA scattering theory breaks down for thick layers and strong parameter contrasts. ACKNOWLEDGEMENTS Sandia National Laboratories is a multi - mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. This research is conducted under the auspices of CRADA (Cooperative Research and Development Agreement) SC11/01780.00 between Carbo Ceramics Inc. and Sandia National Laboratories. The author acknowledges former Carbo R&D Vic e - President Mr. Chad Cannan and former SNL Geophysics Department manage r Ms. Amy Halloran for their interest i n and support of this work. Technical discussions with Project Manager and Principal Investigator Dr. Chester J. Weiss of the SNL Geophysics Department greatly benefited this work. Dr. Lewis C. Bartel, formerly with S NL and presently a consultant to Carbo Ceramics, provided many useful and intuitive insights, and

  8. Recent developments of smart electromagnetic absorbers based polymer-composites at gigahertz frequencies

    Science.gov (United States)

    Idris, Fadzidah Mohd.; Hashim, Mansor; Abbas, Zulkifly; Ismail, Ismayadi; Nazlan, Rodziah; Ibrahim, Idza Riati

    2016-05-01

    The rapid increase in electromagnetic interference has received a serious attention from researchers who responded by producing a variety of radar absorbing materials especially at high gigahertz frequencies. Ongoing investigation is being carried out in order to find the best absorbing materials which can fulfill the requirements for smart absorbing materials which are lightweight, broad bandwidth absorption, stronger absorption etc. Thus, to improve the absorbing capability, several important parameters need to be taken into consideration such as filler type, loading level, type of polymer matrix, physical thickness, grain sizes, layers and bandwidth. Therefore, this article introduces the electromagnetic wave absorption mechanisms and then reveals and reviews those parameters that enhance the absorption performance.

  9. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading.

    Science.gov (United States)

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-01

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

  10. Diffusive and localization behavior of electromagnetic waves in a two-dimensional random medium.

    Science.gov (United States)

    Wang, Ken Kang-Hsin; Ye, Zhen

    2003-10-01

    In this paper, we discuss the transport phenomena of electromagnetic waves in a two-dimensional random system which is composed of arrays of electrical dipoles, following the model presented earlier by Erdogan et al. [J. Opt. Soc. Am. B 10, 391 (1993)]. A set of self-consistent equations is presented, accounting for the multiple scattering in the system, and is then solved numerically. A strong localization regime is discovered in the frequency domain. The transport properties within, near the edge of, and nearly outside the localization regime are investigated for different parameters such as filling factor and system size. The results show that within the localization regime, waves are trapped near the transmitting source. Meanwhile, the diffusive waves follow an intuitive but expected picture. That is, they increase with traveling path as more and more random scattering incurs, followed by a saturation, then start to decay exponentially when the travelling path is large enough, signifying the localization effect. For the cases where the frequencies are near the boundary of or outside the localization regime, the results of diffusive waves are compared with the diffusion approximation, showing less encouraging agreement as in other systems [Asatryan et al., Phys. Rev. E 67, 036605 (2003)].

  11. Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals.

    Science.gov (United States)

    Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny

    2008-05-01

    Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.

  12. Self-focusing of electromagnetic surface waves on a nonlinear impedance surface

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Zhangjie, E-mail: zhangjie-luo-cn@126.com [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States); Chen, Xing [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Long, Jiang; Quarfoth, Ryan; Sievenpiper, Daniel, E-mail: dsievenpiper@eng.ucsd.edu [Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States)

    2015-05-25

    The self-focusing effect of optical beams has been a popular topic of study for quite a while, but such a nonlinear phenomenon at microwave frequencies has never been realized, partially due to the underdevelopment of nonlinear material. In this research, self-focused electromagnetic (EM) surface waves are demonstrated on a circuit-based, power-dependent impedance surface. The formation of a self-focused beam is investigated using a series of discrete-time simulations, and the result is further validated in measurement. It is experimentally observed that, in contrast to the normal scattering of low-power surface waves, high-power waves propagate through the surface while maintaining narrow beam width, and even converge extremely tightly to create a hot spot with higher power. The result is essentially a nonlinear effect of the surface that compensates for the natural tendency of surface waves to diffract. This intriguing experiment can be extended to various potential EM applications such as power-dependent beam steering antennas and nonlinear microwave propagation or dissipation.

  13. Efficient heat generation in large-area graphene films by electromagnetic wave absorption

    Science.gov (United States)

    Kang, Sangmin; Choi, Haehyun; Lee, Soo Bin; Park, Seong Chae; Park, Jong Bo; Lee, Sangkyu; Kim, Youngsoo; Hong, Byung Hee

    2017-06-01

    Graphene has been intensively studied due to its outstanding electrical and thermal properties. Recently, it was found that the heat generation by Joule heating of graphene is limited by the conductivity of graphene. Here we suggest an alternative method to generate heat on a large-area graphene film more efficiently by utilizing the unique electromagnetic (EM) wave absorption property of graphene. The EM wave induces an oscillating magnetic moment generated by the orbital motion of moving electrons, which efficiently absorbs the EM energy and dissipate it as a thermal energy. In this case, the mobility of electron is more important than the conductivity, because the EM-induced diamagnetic moment is directly proportional to the speed of electron in an orbital motion. To control the charge carrier mobility of graphene we functionalized substrates with self-assembled monolayers (SAM). As the result, we find that the graphene showing the Dirac voltage close to zero can be more efficiently heated by EM waves. In addition, the temperature gradient also depends on the number of graphene. We expect that the efficient and fast heating of graphene films by EM waves can be utilized for smart heating windows and defogging windshields.

  14. Controllable synthesis of porous Fe3O4@ZnO sphere decorated graphene for extraordinary electromagnetic wave absorption

    Science.gov (United States)

    Sun, Danping; Zou, Quan; Wang, Yanping; Wang, Yujiao; Jiang, Wei; Li, Fengsheng

    2014-05-01

    For the first time, mesoporous Fe3O4@ZnO sphere decorated graphene (GN-pFe3O4@ZnO) composites with uniform size, considerable porosity, high magnetization and extraordinary electromagnetic (EM) wave absorption properties were synthesized by a simple and efficient three-step method. Structure and morphology details were characterized by X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy and field-emission scanning electron microscopy. Electron microscopy images reveal that pFe3O4@ZnO spheres with obvious porous and core-shell structures are uniformly coated on both sides of the GN sheets without significant numbers of vacancies or apparent aggregation. EM wave absorption properties of epoxy containing 30 wt% GN-pFe3O4@ZnO were investigated at room temperature in the frequency region of 0.2-18 GHz. The absorption bandwidth with reflection loss (RL) values less than -10 dB is up to 11.4 GHz, and the minimal RL is almost -40 dB. The intrinsic physical and chemical properties of the materials, the synergy of Fe3O4 and ZnO, and particularly the unique multi-interfaces are fundamental to the enhancement of EM absorption properties. The as-prepared GN-pFe3O4@ZnO composites are shown to be lightweight, have strong absorption, and broad frequency bandwidth EM absorbers.For the first time, mesoporous Fe3O4@ZnO sphere decorated graphene (GN-pFe3O4@ZnO) composites with uniform size, considerable porosity, high magnetization and extraordinary electromagnetic (EM) wave absorption properties were synthesized by a simple and efficient three-step method. Structure and morphology details were characterized by X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy and field-emission scanning electron microscopy. Electron microscopy images reveal that pFe3O4@ZnO spheres with obvious porous and core-shell structures are uniformly coated on both sides of the GN sheets without significant numbers of vacancies or

  15. Real-time visualization of electromagnetic waves propagating in air using live electro-optic imaging technique.

    Science.gov (United States)

    Kanno, Atsushi; Sasagawa, Kiyotaka; Shiozawa, Takahiro; Tsuchiya, Masahiro

    2010-05-10

    Electromagnetic waves propagating in air are visually observed with phase evolution in real time by live electro-optic imaging technique. We show how geometrical and crystallographic arrangements of an electro-optic sensor plate enable the realization of the real-time visual observation of traveling 100-GHz electromagnetic waves. For this purpose, a generation technique for a 100-GHz optical local oscillator signal at 780 nm was newly developed, whose optical wavelength is suitable for the ultra-parallel RF electric field data acquisition by a Si-CMOS image sensor. (c) 2010 Optical Society of America.

  16. Consideration of radiated electromagnetic wave from partial discharge based on half-wave dipole antenna model; Hanhacho dipole ni motozuita bubun hoden ni yoru hosha denjiha no kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, T.; Okubo, H. [Nagoya University, Nagoya (Japan); Hikita, M. [Kyushu Institute of Technology, Kitakyushu (Japan)

    1997-07-20

    Partial discharge (PD) may take place due to residual defects like metallic particles in SF6 gas insulated power apparatus such as GIS. However, the signal of PD occurring in SF6 gas is very weak and susceptible to external noises in air. Moreover, because of the complicated mechanism of PD, the radiation property of electromagnetic wave from PD has not been clarified, yet. Therefore, it is hard to distinguish the PD signal in SF6 gas from the external noises. From the above points of view, we have been investigating the radiation mechanism of electromagnetic wave from PD. We measured the polarization characteristics of electromagnetic wave radiated from PD in comparison with that of half-wave dipole antennas. The polarization characteristics of PD was explained by the theory of half-wave dipole antenna, rather than that of an infinitesimal dipole antenna. Moreover, we compared the power spectrum received from PD measured by a biconical antenna with that received from the half-wave dipole antenna or infinitesimal dipole. It was found that the power spectrum for PD also corresponded to that for the half-wave dipole antenna with 50cm length. 17 refs., 8 figs.

  17. Fe3O4@polyaniline yolk-shell micro/nanospheres as bifunctional materials for lithium storage and electromagnetic wave absorption

    Science.gov (United States)

    Wang, Xiaoliang; Zhang, Minwei; Zhao, Jianming; Huang, Guoyong; Sun, Hongyu

    2018-01-01

    Unique Fe3O4/polyaniline (PANI) composite with yolk-shell micro/nanostructure (FPys) has been successfully synthesized by a facile silica-assisted in-situ polymerization and subsequent etching strategy. The structural and compositional studies of the FPys composites are performed by employing X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The yolk-shell morphology of the products is confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. When evaluated as anode material for lithium-ion batteries, the as-prepared FPys electrodes deliver superior capacity, better cycling stability and rate capability than those of bare Fe3O4 micro/nanospheres and Fe3O4/PANI core-shell (FPcs) electrodes. Moreover, FPys also exhibits excellent electromagnetic wave absorption performance when comparing to the synthesized Fe3O4-based electromagnetic wave absorbers, in which strong reflection loss and extensive response bandwidth can be achieved simultaneously. The excellent bifunctional properties of FPys material are associated with the specially designed hierarchical micro/nanostructures. The current strategy that application directed structural design can be applied to the synthesis of other multifunctional materials.

  18. Ultrasonic guided wave mechanics for composite material structural health monitoring

    Science.gov (United States)

    Gao, Huidong

    The ultrasonic guided wave based method is very promising for structural health monitoring of aging and modern aircraft. An understanding of wave mechanics becomes very critical for exploring the potential of this technology. However, the guided wave mechanics in complex structures, especially composite materials, are very challenging due to the nature of multi-layer, anisotropic, and viscoelastic behavior. The purpose of this thesis is to overcome the challenges and potentially take advantage of the complex wave mechanics for advanced sensor design and signal analysis. Guided wave mechanics is studied in three aspects, namely wave propagation, excitation, and damage sensing. A 16 layer quasi-isotropic composite with a [(0/45/90/-45)s]2 lay up sequence is used in our study. First, a hybrid semi-analytical finite element (SAFE) and global matrix method (GMM) is used to simulate guided wave propagation in composites. Fast and accurate simulation is achieved by using SAFE for dispersion curve generation and GMM for wave structure calculation. Secondly, the normal mode expansion (NME) technique is used for the first time to study the wave excitation characteristics in laminated composites. A clear and simple definition of wave excitability is put forward as a result of NME analysis. Source influence for guided wave excitation is plotted as amplitude on a frequency and phase velocity spectrum. This spectrum also provides a guideline for transducer design in guided wave excitation. The ultrasonic guided wave excitation characteristics in viscoelastic media are also studied for the first time using a modified normal mode expansion technique. Thirdly, a simple physically based feature is developed to estimate the guided wave sensitivity to damage in composites. Finally, a fuzzy logic decision program is developed to perform mode selection through a quantitative evaluation of the wave propagation, excitation and sensitivity features. Numerical simulation algorithms are

  19. Properties of arrays of microplasmas: application to control of electromagnetic waves

    Science.gov (United States)

    Qu, Chenhui; Tian, Peng; Semnani, Abbas; Kushner, Mark J.

    2017-10-01

    Microplasma arrays (MAs) are being investigated as a method to control the propagation of electromagnetic waves. The use of MAs as an electromagnetic wave controlling material is attractive as the electrical properties of MAs can be rapidly changed through combinations of the choice of operating conditions (e.g. pressure, gas mixture), the spatial distribution of the plasma and applied voltage waveforms. In this paper, results from a computational investigation of the plasma properties of small arrays of microplasmas are discussed. The model systems are arrays of microplasmas sustained in rare gases at pressures of up to 100 Torr in a sealed chamber. Individual plasma cells are ≈100 μm in size. Pulsed dc voltage waveforms having widths of 30 ns are applied at repetition rates of up to 10 MHz. The cross-talk between plasma cells was investigated, as well as the consequences of gas heating and sequencing of the pulses. We found that even without physical barriers between the plasma cells to control cross-talk between cells, the individual character of each cell can be retained; however the plasma cells were not completely independent. The diffusion of metastable excited atomic states and small fluxes of ions did enable adjacent cells to operate at lower voltages. The ability to control microwave propagation through waveguides was computationally investigated by placing a MA inside a standard waveguide and examining the resulting transmission coefficients. We found that for frequencies of tens to 100 GHz, the transmitted power could be controlled by the spatial distribution of the MA cells with respect to the modal structure of the wave.

  20. Radiation of terahertz electromagnetic waves from build-in nano Josephson junctions of cuprate high-T(c) superconductors.

    Science.gov (United States)

    Lin, Shi-Zeng; Hu, Xiao

    2011-04-01

    The nano-scale intrinsic Josephson junctions in highly anisotropic cuprate superconductors have potential for generation of terahertz electromagnetic waves. When the thickness of a superconductor sample is much smaller than the wavelength of electromagnetic waves in vacuum, the superconductor renders itself as a cavity. Unlike conventional lasers, the presence of the cavity does not guarantee a coherent emission because of the internal degree of freedom of the superconductivity phase in long junctions. We study the excitation of terahertz wave by solitons in a stack of intrinsic Josephson junctions, especially for relatively short junctions. Coherent emission requires a rectangular configuration of solitons. However such a configuration is unstable against weak fluctuations, contrarily solitons favor a triangular lattice corresponding to an out-phase oscillation of electromagnetic waves. To utilize the cavity, we propose to use an array of stacks of short intrinsic Josephson junctions to generate powerful terahertz electromagnetic waves. The cavity synchronizes the plasma oscillation in different stacks and the emission intensity is predicted to be proportional to the number of stacks squared.