Transmission Properties Of Electromagnetic Wave Research Articles

Thermal radiative properties of metamaterials and other nanostructured materials: A review

The ability to manufacture, control, and manipulate structures at extremely small scales is the hallmark of modern technologies, including microelectronics, MEMS/NEMS, and nano-biotechnology. Along with the advancement of microfabrication technology, more and more investigations have been performed in recent years to understand the influence of microstructures on radiative properties. The key to the enhancement of performance is through the modification of the reflection and transmission properties of electromagnetic waves and thermal emission spectra using one-, two-, or three-dimensional micro/nanostructures. This review focuses on recent developments in metamaterials-manmade materials with exotic optical properties, and other nanostructured materials, such as gratings and photonic crystals, for application in radiative energy transfer and energy conversion systems.

Investigation of fracture flow paths using alterant geophysical tomography

The mapping of fractures is a problem of major importance to many geotechnical projects. It is a three dimensional problem requiring the use of measurement methods with sufficient resolution and probing range to map fractures at a distance from exposed surfaces. The National Research C6uncil's report on Rock Mechanics Research Requirements [1] identified a need for major improvements in the methods used for mapping remote fractures. This article discusses a new geophysical method (Alterant Geophysical Tomography, AGT) in which tracers are forced into the in situ rock fractures to change the transmission properties of electromagnetic waves propagated between boreholes or tunnels. The theoretical advantages of the method and the results of the first experiment where it was used are also presented. This technique is analogous to the medical diagnostics technique known as X-ray fluoroscopy wherein a tracer is used to attenuate X-rays. The movement of the tracer within the digestive tract or circulatory system of the human body is monitored by measuring the attenuation of X-rays. AGT involves the transmission of an electromagnetic energy field through fractured rock before, during, and/or after a tracer is forced into the fractures. By using alterant geophysical tomography, changes induced by these tracers are mapped in the plane defined by the two boreholes. This approach is intended for geologic environments where fracture flow dominates such that the tracer penetrates the fractures but not the rock matrix.

Reflection and transmission of electromagnetic waves by a semi‐infinite uniaxial plasma moving perpendicular to the plane of incidence

The reflection and transmission properties of electromagnetic waves by a semi‐infinite uniaxial plasma moving perpendicular to the plane of incidence are investigated theoretically for the incident H and E plane wave. In this case, the plasma becomes anisotropic, and electromagnetic field components of the transmitted wave should be hybrid modes. Thus it is shown that the behavior of the power reflection coefficient is remarkably different from that of a stationary one.

Reflection and transmission of electromagnetic waves obliquely incident on a relativistically moving uniaxial plasma slab

The reflection and transmission properties of electromagnetic waves obliquely incident on a relativistically moving uniaxial plasma slab are investigated theoretically and the maxima and minima of the power reflection coefficient as a function of the normalized incident wave frequency ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Omega</tex> ) and the slab velocity ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\beta</tex> ) are discussed for slab motion parallel as well as normal to the slab boundaries. One can predict the nature of variation of the reflection coefficient with respect to any parameter from the variation of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q'</tex> (the root of the dispersion equation) with that parameter. When <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q'</tex> is real and varies rapidly, the oscillations in the reflection coefficient are rapid and when <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q'</tex> differs significantly from the free-space value, the amplitude will be large. In the imaginary range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q'</tex> , the reflection coefficient is nonoscillatory. The discussion of the results is facilitated by introducing a parameter <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> which is a quadratic in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\beta</tex> . For slab motion parallel to the interface, the two slab velocities for a given <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</tex> give rise to same reflection coefficient whilst for normal motion the results are significantly different.

Transmission properties of electromagnetic waves in conical wave guides†

Available approximations in the angular part of the solution of the wave equation for an infinitely long right circular cone with perfectly conducting walls have been used to simplify the evaluation of the eigenvalues of the wave functions relating to wave propagation in a conical region. Exact expressions have been derived for the attenuation constant (α ), phase constant (β) and phase volocity (vP) of a radially propagated electromagnetic wave within the conical guide. Variations in α, β and vP with radial distance have been studied as a function of the flare (semi-vertical) angle. Expressing the resistive and reactive part of the wave impedance in terms of α and β their variation with radial distance has been studied. The wave functions derived from an acoustic analogue for the TE11 mode of excitation in a previous paper by the authors are identical with those obtained here, when the flare angle is very small and the axial length is large.