scholarly journals MOMENTUM OF AN ELECTROMAGNETIC WAVE IN TIME-VARYING DIELECTRIC MEDIA

2021 ◽  
Vol 55 (2 (255)) ◽  
pp. 148-152
Author(s):  
Karen K. Grigoryan
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Wave ◽  
Dielectric Permittivity ◽  
Electromagnetic Waves ◽  
Dielectric Medium ◽  
Time Varying ◽  
Spatial Homogeneity ◽  
Instantaneous Change ◽  
Dielectric Media

In the context of the Abraham–Minkowski controversy, the problem of the propagation of electromagnetic waves in a linear dielectric medium with a time-varying dielectric constant is considered. It is shown that the momentum of an electromagnetic wave in the form of Minkowski is preserved with an instantaneous change in the dielectric permittivity of the medium. At the same time, the Abraham momentum is not conserved, despite the spatial homogeneity of the problem. This circumstance is interpreted as a manifestation of the Abraham force.

scholarly journals Influence of variability of water content in different states on electromagnetic waves parameters affecting accuracy of GPR measurements of asphalt and concrete pavements

2019 ◽  
Vol 262 ◽  
pp. 06012
Author(s):  
Małgorzata Wutke ◽  
Anna Lejzerowicz ◽  
Wioletta Jackiewicz-Rek ◽  
Andrzej Garbacz
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Wave ◽  
Water Content ◽  
Electromagnetic Waves ◽  
Atmospheric Precipitation ◽  
Propagation Speed ◽  
Asphalt Pavements ◽  
Concrete Pavements ◽  
Moisture Conditions ◽  
Accuracy And Repeatability

In the paper a water content effect in various states on the variability of the electromagnetic waves parameters is discussed. This variation can affect accuracy and repeatability of asphalt and concrete pavement thickness estimation with GPR method. In case of asphalt pavements, tests were carried out using the air-coupled 1.0 GHz antenna and included three approaches: two on asphalt road and one of asphalt slabs. In the case of concrete slabs, tests were carried out using a ground-coupled 1.6 GHz antenna on two slabs: reinforced and unreinforced. A high variability of the electromagnetic wave parameters was observed depending on moisture conditions. The increase in the humidity of the medium causes a reduction in the propagation speed of the electromagnetic wave (increasing the dielectric constant of the medium), increasing of waves time propagation, decreasing of reflection amplitude and increasing of frequency attenuation, which should be considered when determining the thicknesses of the construction layers. Studies showed that not always higher air humidity, atmospheric precipitation and consequently wet surface indicate a higher dielectric constant of the medium. It can be concluded that not only the humidity and ambient temperature affect the change in the dielectric constant, but also other factors not resulting from the construction of the pavement as well as material microstructure.

scholarly journals Electromagnetic wave propagation in spatially homogeneous yet smoothly time-varying dielectric media

2016 ◽  
Vol 178 ◽  
pp. 158-166 ◽  
Author(s):  
Armen G. Hayrapetyan ◽  
Jörg B. Götte ◽  
Karen K. Grigoryan ◽  
Stephan Fritzsche ◽  
Rubik G. Petrosyan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Electromagnetic Wave Propagation ◽  
Time Varying ◽  
Dielectric Media ◽  
Spatially Homogeneous

ELECTROMAGNETIC WAVE PROPAGATION IN PERIODIC DIELECTRIC MEDIA: THE PHOTONIC BAND STRUCTURE

1991 ◽  
Vol 05 (16) ◽  
pp. 1041-1054 ◽  
Author(s):  
SASHI SATPATHY ◽  
ZE ZHANG
Keyword(s):  
Band Structure ◽  
Brillouin Zone ◽  
Electromagnetic Waves ◽  
Photonic Band Gap ◽  
Dielectric Medium ◽  
Photonic Band Structure ◽  
Brillouin Zone Boundary ◽  
Dielectric Media ◽  
Dielectric Structures ◽  
Photonic Band

The formation of photonic band structure by electromagnetic waves propagating in a periodic dielectric medium is discussed. The existence of a photonic gap at the Brillouin zone boundary is illustrated in the nearly-free-photon approximation. Numerical results obtained by solving the Maxwell's equations with the planewave method are presented for selected cases. For appropriate dielectric structures, a true photonic band-gap extending throughout the Brillouin zone can exist leading to the possibility of novel physical effects.

Scattering of Electromagnetic Waves by Turbulent, Weakly Ionized Plasmas

1968 ◽  
Vol 23 (1) ◽  
pp. 19-25
Author(s):  
W. Kröll
Keyword(s):  
Dielectric Constant ◽  
Statistical Theory ◽  
Electromagnetic Wave ◽  
Spectral Density ◽  
Cross Section ◽  
Electromagnetic Waves ◽  
Structure Functions ◽  
Weakly Ionized ◽  
Weakly Ionized Plasma ◽  
Monochromatic Electromagnetic Wave

The scattering of a plane, monochromatic electromagnetic wave by the fluctuations of the dielectric constant of a turbulent weakly, ionized plasma is investigated on the basis of the statistical theory of locally isotropic tubulence. The effects of collisions on the fluctuating dielectric constant of the electrons are taken into account. The spectral density determining the scattering cross section is related to the structure functions of the fluctuations of the electron concentration and the temperature. These structure functions are calculated from the transport equations with the use of methods developed in the statistical theory of strong turbulence.

Radiation of electromagnetic waves on instantaneous change of the state of the radiating system

1978 ◽  
Vol 126 (10) ◽  
pp. 311-321 ◽  
Author(s):  
Boris M. Bolotovskii ◽  
Valerii A. Davydov ◽  
V.E. Rok
Keyword(s):  
Electromagnetic Waves ◽  
The State ◽  
Instantaneous Change

Detection of delamination in composites by using electromagnetic penetrating radar

2014 ◽  
Vol 5 (2) ◽  
pp. 151-156
Author(s):  
Z. Mechbal ◽  
A. Khamlichi
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Wave Reflection ◽  
Image Features ◽  
Partial Reflection ◽  
Straight Path ◽  
Reflected Signal ◽  
Short Time ◽  
Intervening Factors

Composites made from E-glass/epoxy or aramid/epoxy are frequently used in aircraft and aerospace industries. These materials are prone to suffer from the presence of delamination, which can reduce severely the performance of aircrafts and even threaten their safety. Since electric conductivity of these composites is rather small, they can propagate electromagnetic waves. Detection of delamination damage can then be monitored by using an electromagnetic penetrating radar scanner, which consists of emitting waves having the form of short time pulses that are centered on a given work frequency. While propagating, these waves undergo partial reflection when running into an obstacle or a material discontinuity. Habitually, the radar is moved at constant speed along a straight path and the reflected signal is processed as a radargram that gives the reflected energy as function of the two-way time and the antenna position.In this work, modeling of electromagnetic wave propagation in composites made from E-glass/epoxy was performed analytically. The electromagnetic wave reflection from a delamination defect was analyzed as function of key intervening factors which include the defect extent and depth, as well as the work frequency. Various simulations were performed and the obtained results have enabled to correlate the reflection pattern image features to the actual delamination defect characteristics which can provide quantification of delamination.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

Oscillations in a Resonator Filled With a Time-Varying Dielectric Medium

1998 ◽  
Vol 52 (6) ◽  
pp. 36-45 ◽  
Author(s):  
Oleg Aleksandrovich Tretyakov ◽  
S. V. Chumachenko
Keyword(s):  
Dielectric Medium ◽  
Time Varying
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