Electromagnetic diffraction by a circular aperture in a plane screen between different media

1969 ◽  
Vol 47 (8) ◽  
pp. 921-930 ◽  
Author(s):  
D. P. Thomas
Keyword(s):  
Integral Equations ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Circular Aperture ◽  
Backscatter Coefficient ◽  
Conducting Plane ◽  
Hertz Vector ◽  
Time Harmonic ◽  
The Waves ◽  
Electromagnetic Diffraction

The problem of diffraction of time harmonic, electromagnetic waves by a circular aperture in a perfectly conducting, plane screen between different media is considered. In this investigation, the incident wave is a plane wave travelling in a direction perpendicular to the screen. A Hertz vector formulation is used to reduce the electromagnetic problem to a system of scalar problems, which is shown to be governed by a pair of simultaneous integral equations of the second kind. The integral equations are valid for all wavelengths and are especially useful when the waves in both media have long wavelengths compared with the radius of the aperture. Low frequency approximations to the tangential components of the electric field in the aperture, the transmission coefficient, and the backscatter coefficient are obtained.

Diffraction by a plane screen

1950 ◽  
Vol 202 (1069) ◽  
pp. 277-284 ◽  
Keyword(s):  
Integral Equation ◽  
Boundary Conditions ◽  
Integral Equations ◽  
Half Plane ◽  
Arbitrary Function ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Integral Equation Method ◽  
Dimensional Problem ◽  
Conducting Plane

The integral-equation method of solving the problem of the diffraction of electromagnetic waves by a perfectly conducting plane screen has been criticized by C. J. Bouwkamp, who claims that it is valid only when certain boundary conditions are satisfied on the edge of the screen. This criticism is answered. It is also shown that, since the equations to be solved are differential-integral equations, an arbitrary function arises in the solution and that this arbitrary function may be chosen so that, although there are singularities at the edge of the screen, there is no radiation of energy from the edge. As an illustration, the three-dimensional problem of diffraction by a half-plane is solved.

scholarly journals On the new modes of planetary-scale electromagnetic waves in the ionosphere

2004 ◽  
Vol 22 (4) ◽  
pp. 1203-1211 ◽  
Author(s):  
G. D. Aburjania ◽  
K. Z. Chargazia ◽  
G. V. Jandieri ◽  
A. G. Khantadze ◽  
O. A. Kharshiladze
Keyword(s):  
Electromagnetic Waves ◽  
Large Scale ◽  
Low Frequency ◽  
Planetary Scale ◽  
Phase Velocities ◽  
F Region ◽  
E Region ◽  
General Dispersion ◽  
Fast Waves ◽  
The Waves

Abstract. 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 (1–5)km s–1 and frequencies (10–1–10–4), and the slow waves propagate with velocities of the local winds with frequencies (10–4–10–6)s–1 and are generated in the E-region of the ionosphere. Fast waves having phase velocities (10-1500)km s–1 and frequencies (1–10–3)s–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)

Rossby–Khantadze electromagnetic planetary vortical motions in the ionospheric E-layer

2011 ◽  
Vol 77 (6) ◽  
pp. 813-828 ◽  
Author(s):  
T. D. KALADZE ◽  
L. V. TSAMALASHVILI ◽  
L. Z. KAHLON
Keyword(s):  
Geomagnetic Field ◽  
Electromagnetic Waves ◽  
Large Scale ◽  
Low Frequency ◽  
Vortical Structures ◽  
Linear Waves ◽  
E Region ◽  
Propagation Properties ◽  
The Waves ◽  
Linear Propagation

AbstractIt is shown that in the earth's conductive ionospheric E-region, large-scale ultra low-frequency Rossby and Khantadze electromagnetic waves can propagate. Along with the prevalent effect of Hall conductivity for these waves, the latitudinal inhomogeneity of both the earth's angular velocity and the geomagnetic field becomes essential. Action of these effects leads to the coupled propagation of electromagnetic Rossby and Khantadze modes. Linear propagation properties of these waves are given in detail. It is shown that the waves lose the dispersing property for large values of wave numbers. Corresponding nonlinear solitary vortical structures are constructed. Conditions for such self-organization are given. It is shown that nonlinear large-scale vortices generate the stronger pulses of the geomagnetic field than the corresponding linear waves. Previous investigations are revised.

scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

scholarly journals Integral Equations for Problems on Wave Propagation in Near-Earth Plasma

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1395
Author(s):  
Danila Kostarev ◽  
Dmitri Klimushkin ◽  
Pavel Mager
Keyword(s):  
Magnetic Field ◽  
Integral Equations ◽  
Field Potential ◽  
Low Frequency ◽  
Fredholm Equation ◽  
Compression Waves ◽  
Parallel Component ◽  
Electric Field Potential ◽  
The Magnetic Field ◽  
Low Frequency Waves

We consider the solutions of two integrodifferential equations in this work. These equations describe the ultra-low frequency waves in the dipol-like model of the magnetosphere in the gyrokinetic framework. The first one is reduced to the homogeneous, second kind Fredholm equation. This equation describes the structure of the parallel component of the magnetic field of drift-compression waves along the Earth’s magnetic field. The second equation is reduced to the inhomogeneous, second kind Fredholm equation. This equation describes the field-aligned structure of the parallel electric field potential of Alfvén waves. Both integral equations are solved numerically.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

Electron Acceleration and Diffusion in the Gyrophase Space by Low-Frequency Electromagnetic Waves

2018 ◽  
Vol 46 (2) ◽  
pp. 225-229
Author(s):  
Hua Huang ◽  
Xiao-Tian Gao ◽  
Xiao-Gang Wang ◽  
Zhi-Bin Wang
Keyword(s):  
Electromagnetic Waves ◽  
Low Frequency ◽  
Electron Acceleration ◽  
And Diffusion
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