The method of multiply reflected waves in the problem of the propagation of electromagnetic waves in regular waveguides (a review)

1982 ◽  
Vol 25 (12) ◽  
pp. 977-996 ◽  
Author(s):  
G. I. Makarov ◽  
L. A. Fedorova
Keyword(s):  
Electromagnetic Waves ◽  
Reflected Waves

scholarly journals Power flow–conformal metamirrors for engineering wave reflections

2019 ◽  
Vol 5 (2) ◽  
pp. eaau7288 ◽  
Author(s):  
Ana Díaz-Rubio ◽  
Junfei Li ◽  
Chen Shen ◽  
Steven A. Cummer ◽  
Sergei A. Tretyakov
Keyword(s):  
Power Distribution ◽  
Electromagnetic Waves ◽  
Power Flow ◽  
Flow Distribution ◽  
Physical Nature ◽  
Wave Reflections ◽  
Reflected Waves ◽  
Anomalous Reflection ◽  
Unit Cells ◽  
Reflecting Surfaces

Recently, the complexity behind manipulations of reflected fields by metasurfaces has been addressed, showing that, even in the simplest scenarios, nonlocal response and excitation of auxiliary evanescent fields are required for perfect field control. In this work, we introduce purely local reflective metasurfaces for arbitrary manipulations of the power distribution of reflected waves without excitation of any auxiliary evanescent field. The method is based on the analysis of the power flow distribution and the adaptation of the reflector shape to the desired distribution of incident and reflected fields. As a result, we find that these power-conformal metamirrors can be easily implemented with conventional passive unit cells. The results can be used for the design of reflecting surfaces with multiple functionalities and for waves of different physical nature. In this work, we present the cases of anomalous reflection and beam splitting for both acoustic and electromagnetic waves.

The effect of boundaries on wave propagation in a liquid-filled porous solid: III. Reflection of plane waves at a free plane boundary (general case)

1962 ◽  
Vol 52 (3) ◽  
pp. 595-625 ◽  
Author(s):  
H. Deresiewicz ◽  
J. T. Rice
Keyword(s):  
Electromagnetic Waves ◽  
Plane Waves ◽  
Body Waves ◽  
Porous Solid ◽  
Plane Boundary ◽  
Field Equations ◽  
Attenuation Coefficients ◽  
Reflected Waves ◽  
Three Body ◽  
Analytical Expressions

abstract A general solution is derived of Biot's field equations governing small motions of a porous solid saturated with a viscous liquid. The solution is then employed to study some of the phenomena attendant upon the reflection from a plane, traction-free boundary of each of the three body waves predicted by the equations. The problem, though more complex, bears some similarity to that of electromagnetic waves in a conducting medium, in that some of the reflected waves are inhomogeneous, planes of constant amplitude not coinciding with planes of constant phase. Analytical expressions are displayed for the phase velocities, attenuation coefficients, angles of reflection and the amplitude ratios, and explicit formulas are given for the limiting cases of low and high frequencies, representing first-order corrections for porosity of the solid and viscosity of the liquid, respectively. The paper concludes with a presentation of results of numerical calculations pertinent to a kerosene-saturated sandstone.

scholarly journals Features of reflection of electromagnetic waves from nanometric perforated multilayers including epsilon-near-zero metamaterials

2019 ◽  
Vol 6 ◽  
pp. 22 ◽  
Author(s):  
Evgenii Starodubtsev
Keyword(s):  
Electromagnetic Waves ◽  
Phase Change Materials ◽  
Extreme Values ◽  
Exciting Radiation ◽  
Substrate Material ◽  
Boundary Problems ◽  
Reflected Waves ◽  
Main Layer ◽  
System Parameters ◽  
Epsilon Near Zero

Using the exact solutions of electromagnetic boundary problems, analytical modeling of reflection of electromagnetic waves from nanometric perforated multilayers has been carried out. New features of operation of the multilayers including the substrate or layers of epsilon-near-zero (ENZ) materials are established. Presence of the ENZ main layer or substrate leads to the quickly changing and extreme values of phase and module of amplitude reflection coefficients depending on the system parameters. The ENZ (or metallic for the thicker systems) substrate has a significant impact on the transformation of phase difference of the reflected waves. The detailed numerical analysis of the obtained results for the multilayers including silver or phase change materials (germanium antimony tellurium alloy, vanadium dioxide) components is performed. The considered reflection characteristics are reasonably “stable” to variation of the system parameters such as oblique incidence of the exciting radiation (for TE or TM polarization), possible presence of magnetic properties of the layers and effective electromagnetic anisotropy of the substrate material. The obtained results can be used to develop ultra-thin (with significantly subwavelength thicknesses) transformers of phase and amplitude of reflected radiation, holograms, metasurfaces and other nanophotonics applications.

scholarly journals Simulations of direct and reflected waves trajectories for in situ GNSS-R experiments

2014 ◽  
Vol 7 (1) ◽  
pp. 1001-1062 ◽  
Author(s):  
N. Roussel ◽  
F. Frappart ◽  
G. Ramillien ◽  
C. Desjardins ◽  
P. Gegout ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Specular Reflection ◽  
Elevation Angle ◽  
Test Site ◽  
Satellite System ◽  
Geometric Problem ◽  
Reflected Waves ◽  
The North ◽  
The Earth ◽  
Global Navigation Satellite

Abstract. The detection of Global Navigation Satellite System (GNSS) signals that are reflected off the surface, together with the reception of direct GNSS signals offers a unique opportunity to monitor water level variations over land and ocean. The time delay between the reception of the direct and the reflected signal gives access to the altitude of the receiver over the reflecting surface. The field of view of the receiver is highly dependent on both the orbits of the GNSS satellites and the configuration of the study site geometries. A simulator has been developed to determine the accurate location of the reflection points on the surface by modelling the trajectories of GNSS electromagnetic waves that are reflected on the surface of the Earth. Only the geometric problem have been considered using a specular reflection assumption. The orbit of the GNSS constellations satellite (mainly GPS, GLONASS and Galileo), and the position of a fixed receiver are used as input. Three different simulation modes are proposed depending on the choice of the Earth surface (local sphere or ellipsoid) and the consideration of topography likely to cause masking effects. Atmospheric delay effects derived from adaptive mapping functions are also taken into account. This simulator was developed to determine where the GNSS-R receivers should be located to monitor efficiently a given study area. In this study, two test sites were considered. The first one at the top of the Cordouan lighthouse (45°35'11'' N; 1°10'24'' W; 65 m) and the second one in the shore of the Geneva lake (46°24'30'' N; 6°43'6'' E, with a 50 m receiver height). This site is hidden by mountains in the South (altitude up to 2000 m), and overlooking the lake in the North (altitude of 370 m). For this second test site configuration, reflections occur until 560 m from the receiver. The geometric differences between the positions of the specular reflection points obtained considering the Earth as a sphere or as an ellipsoid were found to be on average 44 cm for satellites elevation angle greater than 10° and 1 m for satellite elevation angle between 5° and 10°. The simulations highlight the importance of the DEM integration: differences with and without integrating the DEM were found to be about 3.80 m with the minimum elevation angle equal to 5° and 1.4 m with the minimum elevation angle set to 10°. The correction of the tropospheric effects on the signal leads to geometric differences about 24 m maximum for a 50 m receiver height whereas the maximum is 43 cm for a 5 m receiver height. These errors deeply increase with the receiver height. By setting it to 300 m, the geometric errors reach 103 m for satellite elevation angle lower than 10°. The tests performed with the simulator presented in this paper highlight the importance of the choice of the Earth representation and also the non-negligible effect of the troposphere on the specular reflection points positions. Various outputs (time-varying reflection point coordinates, satellites positions and ground paths, wave trajectories, Fresnel first surfaces, etc.) are provided either as text or KML files for a convenient use.

scholarly journals Electromagnetic Field Simulation in a Microwave Chamber with Multiple Waveguides

2018 ◽  
Vol 167 ◽  
pp. 03001 ◽  
Author(s):  
Jaekyung Kim ◽  
Euysik Jeon
Keyword(s):  
Electromagnetic Field ◽  
Ceramic Material ◽  
Electromagnetic Waves ◽  
Energy Intensity ◽  
Microwave Energy ◽  
Proper Understanding ◽  
Reflected Waves ◽  
Electromagnetic Field Distribution ◽  
Field Simulation ◽  
Uniform Electromagnetic Field

While microwaves have many features and advantages, problems may occur, including non-heating, partial overheating, and fire due to damaged magnetrons caused by reflected waves, when they are used without a proper understanding of the permittivity of the object to be heated, the electromagnetic field distribution, the matching between the chamber and the waveguide, and the reflected electromagnetic waves. Simulation was performed using the Ansys HFSS tool. Conditions for the uniform electromagnetic field were derived using the distance from the waveguides to the ceramic material as well as the microwave energy intensity as major parameters.

TRANSFORMATION OF SOUND AND ELECTROMAGNETIC WAVES IN NON-STATIONARY MEDIA

2010 ◽  
Vol 24 (18) ◽  
pp. 1951-1961 ◽  
Author(s):  
A. R. MKRTCHYAN ◽  
A. G. HAYRAPETYAN ◽  
B. V. KHACHATRYAN ◽  
R. G. PETROSYAN
Keyword(s):  
Energy Flux ◽  
Sound Wave ◽  
Electromagnetic Waves ◽  
Reflection And Transmission Coefficients ◽  
Sound Waves ◽  
Reflection And Transmission ◽  
Reflected Waves ◽  
Transmission Coefficients

Transformation (reflection and transmission) of sound and electromagnetic waves are considered in non-stationary media, properties of which abruptly change in time. Reflection and transmission coefficients for both amplitudes and intensities of sound and electromagnetic waves are obtained. Quantitative relations between the reflection and transmission coefficients for both sound and electromagnetic waves are given. The sum of the energy flux reflection and transmission coefficients for both types of waves is not equal to one (for sound waves it is greater than one). The energy of both waves is not conserved, that is, exchange of the energy occurs between the corresponding waves and medium. As a result, the sound wave obtains a notable property: the transmitting wave carries energy equal to the sum of the energies of the incident and reflected waves. A possibility of the amplification of sound waves and transformation of their frequencies is illustrated.

ELECTROMAGNETIC WAVES IN A BOUNDED, ANISOTROPIC PLASMA

1962 ◽  
Vol 40 (7) ◽  
pp. 887-905 ◽  
Author(s):  
K. A. Graf ◽  
M. P. Bachynski
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Electromagnetic Waves ◽  
Plane Electromagnetic Wave ◽  
Plasma Boundary ◽  
Plasma Properties ◽  
Magnetic Field Data ◽  
Reflected Waves ◽  
Quartic Equation ◽  
The Magnetic Field

The interaction of a plane, electromagnetic wave with a flat, uniform free-space – plasma interface in a static magnetic field has been considered for arbitrary angles of incidence. The dispersion relation for the plasma is a complex quartic equation which reduces to a quadratic if the static magnetic field and plasma boundary are oriented along any one of the rectangular co-ordinate axes. (These axes need not simultaneously be the same for the plasma and the magnetic field.)Numerical results are presented for the attenuation and phase constants for each of the two possible waves in the plasma, for each orientation of the static magnetic field. Data are given for various angles of incidence, plasma properties, and orientations of the static magnetic field relative to the plasma boundary.Inspection of the fields in the plasma reveals some interesting aspects. In certain cases, waves which appear to move upward towards the plasma interface exist. Since these waves may carry energy into the plasma, they have been referred to as "backward" waves. Totally reflected waves which have both finite attenuation and finite phase coefficients can also exist in the plasma. These have been termed "modified Sommerfeld" waves.

Simulation and Experiments on Signals of Ground-Penetrating Radar in Soil Cement

2020 ◽  
pp. 2158003
Author(s):  
Zhezhe Hou ◽  
Yanliang Du
Keyword(s):  
Dielectric Constant ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Soil Layer ◽  
Center Line ◽  
Reflected Waves ◽  
Soil Cement ◽  
Subgrade Soil ◽  
Ground Penetrating ◽  
Radar Wave

Subgrade bedding is a key element of railway structure in stability and durability, and it is almost made of soil cement. The dielectric constant, compaction and curing ages of soil cement with different moisture contents were measured. The relation among curing ages, moisture content, compaction of soil cement and electromagnetic features was analyzed. The model of layered soil cement was established to simulate ground-penetrating radar (GPR) electromagnetic waves in the soil cement. The variation rules of dielectric constant and amplitude of radar signals were obtained. The electromagnetic features, i.e. velocity, frequency and amplitude, were analyzed. Ground-penetrating radar was used to detect the railway subgrade soil layer. Based on the center line of the subgrade, there were nine detection lines for every 1[Formula: see text]m to detect the density and smoothness of the subgrade soil layer. Based on the radar wave events and reflected waves, the subgrade condition can be judged.

MODULATION OF ELECTROMAGNETIC WAVES BY ACOUSTIC WAVES IN A PLASMA

1964 ◽  
Vol 42 (8) ◽  
pp. 1635-1642 ◽  
Author(s):  
Mahendra Singh Sodha ◽  
Carl James Palumbo
Keyword(s):  
Electromagnetic Wave ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Free Space ◽  
Electromagnetic Waves ◽  
Reflected Waves

This communication presents an analysis of the modulation of an electromagnetic wave, propagating in a plasma, in which an acoustic wave is present. The modulation of the transmitted and reflected waves from a plasma-free space interface has also been analyzed. A discussion of the results obtained has also been given.

1D and 2D phase gradient perforated dielectric reflective surfaces atmmWave

2017 ◽  
Vol 10 (4) ◽  
pp. 446-452 ◽  
Author(s):  
Mustafa K. Taher Al-Nuaimi ◽  
Wei Hong ◽  
Xiqi Gao
Keyword(s):  
Electromagnetic Waves ◽  
Normal Incidence ◽  
Electrical Conductor ◽  
Wave Regime ◽  
Phase Gradient ◽  
Reflected Waves ◽  
Dielectric Surfaces ◽  
Full Wave ◽  
Perfect Electrical Conductor ◽  
Reflective Surfaces

This paper presents the design of all dielectric non-absorptive phase gradient reflective surfaces that can be used to manipulate the reflected electromagnetic waves at millimeter-wave regime. Compared with a bare perfect electrical conductor reflector which obeys the classical Snell's law of reflection, the presented design can effectively alter both the shape and level of the backscattered energy and thus radar cross section (RCS) reduction is achieved in the specular direction. One- and two-dimensional phase gradient reflective dielectric surfaces of phase change about 72° across their apertures are designed and their ability to manipulate the reflected waves under normal incidence are investigated both by means of full-wave simulations and experimentally tested for validation. More than 6 dB of specular RCS reduction is achieved from about 66.5–78.2 GHz.

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