Top PDF Electromagnetic surface-wave propagation along a dielectric cylinder of elliptical cross section

Electromagnetic surface-wave propagation along a dielectric cylinder of elliptical cross section

Electromagnetic surface-wave propagation along a dielectric cylinder of elliptical cross section

Keepi ng the spread of the field outside the dielectric tape within a reasonable distance from the surface of the dielectric guide, the loss fa.ctor of the eHEll mode on a dielectric tap[r]

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Propagation in a Helical Waveguide with Inhomogeneous Dielectric Profiles in Rectangular Cross Section

Propagation in a Helical Waveguide with Inhomogeneous Dielectric Profiles in Rectangular Cross Section

Several methods of investigation of propagation were developed for study of empty curved waveguide and bends [7–10]. The results of precise numerical computations and extensive analytical investigation of the angular propagation constants were presented for various electromagnetic modes which may exit in waveguide bends of rectangular cross section [7]. A new equivalent circuit for circular E-plane bends, suitable for any curvature radius and rectangular waveguide type was presented in Ref. [8]. An accurate and efficient method of moments solution together with a mode-matching technique for the analysis of curved bends in a general parallel-plate waveguide was described in the case of a rectangular waveguides [9]. A rigorous differential method describing the propagation of an electromagnetic wave in a bent waveguide was presented in Ref. [10].
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Wave Propagation in a Helical Waveguide with Slab and Rectangular Dielectric Profiles, and Applications

Wave Propagation in a Helical Waveguide with Slab and Rectangular Dielectric Profiles, and Applications

Abstract—This paper presents a rigorous approach for the propagation of electromagnetic (EM) fields along a helical waveguide with slab and rectangular dielectric profiles in the rectangular cross section. The main objective is to develop a numerical method for the calculation of the output fields, for an arbitrary step’s angle and the radius of the cylinder of the helical waveguide. The other objectives are to present the technique to calculate the dielectric profiles and their transverse derivatives in the cross-section and to demonstrate the ability of the model to solve practical problems with slab and rectangular dielectric profiles in the rectangular cross section of the helical waveguide. The method is based on Fourier coefficients of the transverse dielectric profile and those of the input wave profile. Laplace transform is necessary to obtain the comfortable and simple input- output connections of the fields. This model is useful for the analysis of helical waveguides with slab and rectangular dielectric profiles in the metallic helical waveguides in the microwave and the millimeter- wave regimes. The output power transmission and the output power density are improved by increasing the step’s angle or the radius of the cylinder of the helical waveguide, especially in the cases of space curved waveguides.
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Radar Cross Section Reduction Property of High Impedance Surface on a Lossy Dielectric

Radar Cross Section Reduction Property of High Impedance Surface on a Lossy Dielectric

Since the pioneering work of high impedance surfaces (HIS) in 1999 by Daniel Sievenpiper [1], it found a lot of applications because of its artificial magnetic conductor (AMC) property at a particular frequency. It consists of frequency selective surfaces (FSS) over a metal backed dielectric substrate. At the resonant frequency, the input impedance of HIS is characterized by very high real part and the imaginary part showing a smooth transition through zero [2]. Thus most of the incident electromagnetic wave is reflected back without any phase reversal resulting in +1 reflection coefficient. Because of this interesting metamaterial property, HIS has found many relevant application in microwaves areas such as radar cross section reduction, low-profile antennas, Fabry-Perot or Leaky wave antennas, EMI/EMC applications, etc.
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Theoretical and Experimental Studies of Magnetic Field on Electromagnetic Wave Propagation in Plasma

Theoretical and Experimental Studies of Magnetic Field on Electromagnetic Wave Propagation in Plasma

Abstract—A spacecraft will experience the well-known “blackout” problem in the re-entry into the Earth’s atmosphere, which results in communication failures between the spacecraft and ground control center. It is important to study the blackout mitigation method. The effects of external magnetic field on electromagnetic wave propagation in plasma are studied by theoretical and experimental methods in this paper. The numerical results show that the attenuation of electromagnetic wave in plasma is reduced by the presence of a magnetized field. The propagation properties of electromagnetic wave in unmagnetized and magnetized plasma have been studied experimentally with plasma torch, and the experimental results are in good agreement with the theory. Both the theoretical and experimental results indicate that magnetic window is an alternative and promising way to improve the radio blackout issue.
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Electromagnetic Wave Propagation in Nonlocal Media: Negative Group Velocity and Beyond

Electromagnetic Wave Propagation in Nonlocal Media: Negative Group Velocity and Beyond

We end this paper by some general remarks. The ultimate origin of nonlocality is the non-vanishing finite spatial extension of the wavefunctions of the particles constituting the medium under interest [21]. This means that a self-consistent approach, at least in the semi- classical sense, should directly provide expressions for the response functions that include both temporal and spatial dispersion. While many such methods are available in literature, e.g., see [1] and [21], the computational complexity of a realistic problem comprising, say, periodic arrangements of unit cells engineered to achieve desired electromagnetic performance, makes the method very difficult to apply in iterated design procedures. Instead, one may develop a suitable effective-field theory, taking into consideration some of the physical mechanisms that generate nonlocality in the electromagnetic response. Then, this theory, once tested and refined, can be used in an iterative optimization algorithm to achieve the required goals. Moreover, it may be possible to achieve nonlocal effects even within the regime of classical electrodynamics by carefully exploiting near-field interactions at the nanoscale [22].
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Molecular versus electromagnetic wave propagation loss in macro scale environments

Molecular versus electromagnetic wave propagation loss in macro scale environments

Abstract—Molecular communications (MC) has been studied as a bio-inspired information carrier for micro-scale and nano- scale environments. On the macro-scale, it can also be considered as an alternative to electromagnetic (EM) wave based systems, especially in environments where there is significant attenuation to EM wave power. This paper goes beyond the unbounded free space propagation to examine three macro-scale environments: the pipe, the knife edge, and the mesh channel. Approximate analytical expressions shown in this paper demonstrate that MC has an advantage over EM wave communications when: (i) the EM frequency is below the cut-off frequency for the pipe channel, (ii) the EM wavelength is considerably larger than the mesh period, and (iii) when the receiver is in the high diffraction loss region of an obstacle.
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Scattering of Electromagnetic Plane Wave by a Perfectly Conducting Slit and a PEMC Parallel Cylinder

Scattering of Electromagnetic Plane Wave by a Perfectly Conducting Slit and a PEMC Parallel Cylinder

Abstract—Diffraction of a plane wave from a geometry which contains an infinite slit in a perfect electric conducting (PEC) plane and a perfectly electromagnetic conductor (PEMC) cylinder is presented. The method is based on the extension of Clemmow, Karp and Russek solution for the diffraction by a wide slit. The results are compared with the published work and agreement is fairly good.

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The Scattering from an Elliptic Cylinder Irradiated by an Electromagnetic Wave with Arbitrary Direction and Polarization

The Scattering from an Elliptic Cylinder Irradiated by an Electromagnetic Wave with Arbitrary Direction and Polarization

Abstract—The analytical expression of scattering field from a conductor elliptic cylinder is presented, as the electromagnetic wave propagating vertical to the axis of an elliptic cylinder with arbitrary incident angle and polarization. The obtained result is in agreement with that in the reference when we use this analytical expression to calculate the scattering field from a cylinder. Simulations show that the vertical size of the elliptic cylinder greatly affects the scattering field when we observe it in the direction perpendicular to the direction of the incident wave. The scattering field is strong as the polarization direction of incident wave parallel to the axis of the elliptic cylinder. The algorithm used in the article is valid to investigate the scattering characteristics of other elliptic cylinders. The obtained result offers a theoretical foundation for the practical applications such as electromagnetic remote sensing of target’s size and shape.
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Research on the Propagation of Extremely Low Frequency Electromagnetic Wave in Shallow Sea Area

Research on the Propagation of Extremely Low Frequency Electromagnetic Wave in Shallow Sea Area

The radiation from an electric dipole source has been studied in great details. Among many standout researchers, Weaver [10] derived the solutions for horizontal and vertical electric dipole (HED/VED) in a two-layer conductive medium, and the two-layer model was extended by [11–16]. Furthermore, the works in [9] and [17–19] gave the solutions on the radiation problem when the HED or VED was placed in a conducting medium or dielectric layer. Finally, Fares et al. [20] conducted experiments to verify Weaver’s work. They measured the magnetic fields generated by HED and VED antennas in shallow seawater at bandwidth of 20 to 500 Hz, and the results indicated that the magnetic fields picked up by tri-axial magnetometer were consistent with Weaver’s model.
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Application of Surface Electromagnetic Wave for Wireless Communication in Arctic

Application of Surface Electromagnetic Wave for Wireless Communication in Arctic

A study of radio wave propagation over the ice-covered sea areas is of great importance in the connection with the problem of the surface electromagnetic wave (SEW). Many of VLF-LF-MF-HF radio systems in the Arctic seas work in the range of 100 kHz to 5 MHz. The review of literature on the area of water of the Arctic and the Antarctic showed that the electromagnetic characteristics of the “ice-sea” stratified media with sharply contrasting electric properties and the processes of radio wave propagation over them are not sufficiently studied [1,2]. The aim of this study is efficiency assessment of communication and navigation channels in the Arctic regions on the basis of analysis of numerical data of modeling of the LF-MF-HF radio wave propagation over the “ice-sea” stratified medium within the range of 100-5000 kHz (attenuation function W, electromagnetic field level E).
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Surface Effects on the Scatter of SH Wave by a Shallow Buried the Elliptical Hole

Surface Effects on the Scatter of SH Wave by a Shallow Buried the Elliptical Hole

With the rapid development of micro-nano-components, there is an increas- ing demand for understanding the mechanical behavior of small-sized materials and structures, which often differ distinctly from their macroscopic counterparts. As the volume of the object decreases, the ratio of surface area to volume in- creases, and the surface effect is significant, thus exhibiting mechanical behavior different from the macroscopic case. For example, geckos can walk freely on ver- tical walls and mosquitoes walk on the water. Based on Gurtin’s surface elasticity theory [17] [18], Sharma, et al. [19] studied the size dependence of the elastic field around the nano-cylindrical and nano-sphere inclusions in the whole space. Using the wave function expansion method, Wang, et al. [20] [21] discussed the diffraction of plane compressional wave (P-wave) in nano-hole. Shen, et al. [22] discussed the influence of surface effects on the stress field around na- no-inclusions. Ou, et al. [23] [24] [25] discussed the mechanical behaviors of in- clusions and holes subjected to uniform loads at nano-scale.
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The propagation of surface plasmons on metal hole arrays with elliptical holes in various configurations

The propagation of surface plasmons on metal hole arrays with elliptical holes in various configurations

We will present a cross section where λ is plotted against k. This shows the band structure of the sample the clearest. The four different types of cross sections that we will make are shown in figure 24, they are the same as in chapter 5. The polarization of the light in the measurements is 0˚as defined in figure 24. The four different cross sections are shown in figure 31. At least three bands are clearly visible. The bands that have a higher wavelength (and therefore a lower energy) contain more light than the bands with a lower wavelength. The low bands are therefore hard to distinguish. A possible explanation for this is that the semiconductor layers, responsible for the gain, does not work that well. V.T. Tenner et al. 4 measured the fluorescence as a function of wavelength, and found that for the wavelengths in the
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Electromagnetic Modeling of Metallic Elliptical Plates

Electromagnetic Modeling of Metallic Elliptical Plates

Using Equations (6)-(8), the matrix elements and the unknown coefficients are calculated assuming that the potential of the plate is equal to 1. Using Equations (8) and (9), the capacitance of an elliptical isolated disk with eccentricity e = 0.85 has been calculated. The conver- gence of the computed numerical values is illustrated in shown in Figure 5. The converged value of the capaci- tance is 49.873 pF. The computed capacitance as a func- tion of eccentricity is presented in Figure 6 and the nu- merical value of the capacitance is presented in Table 1. The numerical results can be compared with a closed form solution for a circular disk (eccentricity=0) in Ta- ble 1 [8].
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Propagation of Natural Waves on Plates of a Variable Cross Section

Propagation of Natural Waves on Plates of a Variable Cross Section

It should also be noted that the numerical analysis of the dispersion Equation (33) does not allow to show the presence of strictly limit the speed of wave propagation modes, since the computer cannot handle infinitely large quantities. We can only speak about the numerical stability result in a large frequency range, which is confirmed by research. For example, when tg ϕ = 2 0.2 value of the phase velocity of a measured without shear wave velocity at ω = 3 and ω = 40 It differs fifth sign that corresponds to the accuracy of calculations, resulting in test problem.
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Concept of Experimental Simulator for Studying Longitudinal Magnetic Wave Propagation in Dielectric Samples

Concept of Experimental Simulator for Studying Longitudinal Magnetic Wave Propagation in Dielectric Samples

Abstract—A concept of an experimental simulator for studying longitudinal magnetic waves in dielectric samples and its electrodynamic justification are presented. The simulator is intended to control impact power and frequencies of wave processes. The simulator is realized as a two-channel junction consisting of perpendicularly crossed infinite rectangular waveguides with slot coupling. The simulation process is based on cyclic mechanical displacements of dielectric samples along the longitudinal axis of the waveguide in a quasi-stationary magnetic field localized in the slot region.
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Computing with Large Time Steps for Electromagnetic Wave Propagation in Multilayered Homogeneous Media

Computing with Large Time Steps for Electromagnetic Wave Propagation in Multilayered Homogeneous Media

Gaussian pulse propagates in a perfect conducting cavity [14]. The cavity has 200 grid cells with Δ x = 0 . 0005 m, and the first fifty cells have dielectric material with relative permittivity r = 2 . 3. Other grid cells in the cavity are considered to be free space ( r = 1). The Gaussian pulse is initialized at the centre of the domain and is expressed as e −w 2 t 2 , where w = 4 . 14 × 10 10 1/s. As time advances the pulse propagates left [14]. The representation of the electric fields after time t = 0 . 1418 , 0 . 2752, and 0.4186 ns are shown in Figure 7. As in the previous case of variable impedance media, when waves originating in a Riemann problem hit a material interface, part of the wave is transmitted, and part reflects back from the interface. These transmitted and reflected waves update appropriate range of downwind and upwind grid cell relative to the interface depending on locally defined wave speed. The computational domain is also bounded with the perfect electric conducting (PEC) boundaries. As shown in Figures 7(b) and 7(c), the outgoing wave from the boundaries completely reflect back into the computational domain so as to have n× E = E y = 0 at PEC boundaries. This PEC boundary condition implementation was earlier described in detail by the authors in [10] for homogeneous medium. From the results the profile of electric field again agrees very well with the analytical solution for ν 1. The measured amplitude of transmitted and reflected waves, error L 2 , and CPU time for varying ν are again tabulated in Table 3 at t = 0 . 4186 ns. In this table E t is the amplitude of transmitted wave. The incident pulse initially hits the interface, and the amplitude of reflected wave is E r 1 in the table. As shown in Figure 7(b), the left moving transmitted wave after reflection from PEC boundary again hits the dielectric interface. A part of the wave is again reflected from the interface, and amplitude of this reflected wave is represented by E r 2 in the table. As in the homogeneous case [10], the discretization error decreases with increase in ν due to decrease in the number of operations with increasing Δ t . Table 3. Performance of LTS algorithm with varying ν , Z ( x ) = Z 0 , PEC boundaries.
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Surface Wave Propagation in a Generalized Thermoelastic Material with Voids

Surface Wave Propagation in a Generalized Thermoelastic Material with Voids

and Scalia [10] studied the spatial and temporal behavior in linear thermoelasticity of materials with voids. A theo- ry of thermoelastic materials with voids and without en- ergy dissipation is developed by Cicco and Diaco [11]. Ciarletta et al. [12] presented a model for acoustic wave propagation in a porous material which also allows for propagation of a thermal displacement wave. Singh [13] studied the wave propagation in a homogeneous, iso- tropic generalized thermoelastic half space with voids in context of Lord and Shulman theory. Ciarletta et al. [14] studied the linear theory of micropolar thermoelasticity for materials with voids. Recently, Aoudai [15] derived the equations of the linear theory of thermoelastic diffu- sion in porous media based on the concept of volume fraction.
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On Propagation Problems of New Surface Wave in Cubic Piezoelectromagnetics

On Propagation Problems of New Surface Wave in Cubic Piezoelectromagnetics

kumyan (BGM) wave can propagate in such piezoelec- tromagnetics. It is worth noticing that the surface BGM- wave in piezoelectromagnetics is analogous to the well- known surface Bleustein-Gulyaev (BG) wave [18,19] pro- pagating in the transversely isotropic piezoelectrics. More- over, recent book [20] has analytically found that the BGM-wave can also propagate in the cubic piezoelec- tromagnetics. This book published in 2011 has also dis- covered seven new SH-SAWs propagating on the surface of the cubic piezoelectromagnetics and discussed the main differences between the wave propagations in the cubic piezoelectromagnetics and the transversely isotro- pic piezoelectric composite materials. Note that the wave propagations in cubic piezomagnetics [21] and cubic pie- zoelectrics [22] are also different from those in the trans- versely isotropic materials. Also, Ref. [23] has stated that SH-SAWs can easily be produced by electromagnetic acoustic transducers (EMATs). According to books [24, 25], the EMATs offer a series of advantages over tradi- tional piezoelectric transducers. So, the EMATs can be used for measurements of SH-SAW characteristics when the wave propagations in the piezoelectrics, piezomag- netics, or piezoelectromagnetics are studied.
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Wave Dynamics in the Channels of Variable Cross-Section

Wave Dynamics in the Channels of Variable Cross-Section

Dynamics of long sea waves in the channels of variable depth and variable rectangular cross-section is discussed within various approximations – from the shallow water equations to those of nonlinear dispersion theory. General approach permitting to find traveling (non-reflective) waves in inhomoge- neous channels is demonstrated within the framework of the shallow water linear theory. The appro- priate conditions are determined by solving a system of ordinary differential equations. The so-called self-consistent channel in which the width is connected with its depth in a specific way is studied in detail. Within the linear theory of shallow water, a wave does not reflect from the bottom irregulari- ties. The wave shape remains unchanged on the records of the wave gauges (mareographs) fixed along the channel axis, but it varies in space. Nonlinearity and dispersion lead to the wave transfor- mation in such a channel. Within the framework of the shallow water weakly nonlinear theory, the wave shape is described by the Riemann solution, and the wave breaks (gradient catastrophe) quicker in the zones of decreasing depth. The modified Korteweg – de Vries equation describing evolution of a solitary wave of weak but finite amplitude in a self-consistent channel, the depth of which can vary arbitrary, is derived. Some examples of a solitary wave transformation in such a channel are analyzed (particularly, a soliton adiabatic transformation in the channel with the slowly varying parameters, and a solitary wave fission into the group of solitons after it has passed the zone where the depth changes abruptly. The obtained solutions extend the class of those represented earlier by S.F. Dotsen- ko and his colleagues.
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