Scattering of TM excitation by coupled and partially buried cylinders at the interface between two media

An analysis of scattering from coupled conducting cylinders near the planar interface between two semi-infinite, homogeneous halfspaces of different electromagnetic properties and from partially buried conducting cylinders is presented. The perfectly conducting cylinders of general cross sections are of infinite extent and the excitation is transverse magnetic to the cylinder axes. Coupled integral equations for the unknown current induced on the cylinders are derived and a numerical method for solving them is described. In addition, a simple technique is employed to determine the far-zone scattered field from knowledge of the cylinder current. Data displaying the distribution of the induced current and the scattered field patterns for cylinders of interest are presented and discussed.     

TE scattering by partially buried and coupled cylinders at theinterface between two media

The scattering of transverse electric (TE) illumination by partially buried conducting cylinders and by coupled conducting cylinders in two media is studied. The conducting cylinders are of general cross section and of infinite extent. Data depicting far-zone scattered fields for various cylinders and media parameters of interest are presented, and the highly lobate patterns which differ significantly from those due to cylinders in homogeneous space are discussed and explained     

Current induced by TE excitation on a conducting cylinder located near the planar interface between two semi-infinite half-spaces

An analysis is presented for determining the current induced by a known transverse electric excitation on a perfectly conducting cylinder located near the planar interface separating two semi-infinite, homogeneous half-spaces of different electromagnetic properties. The conducting cylinder of general cross section is of infinite extent and the excitation is transverse electric to the cylinder axis. Two types of integral equations, the magnetic field integral equation and the electric field integral equation, are formulated, and the Green's functions for the integral equations are derived in an appendix. Numerical solution methods for solving the integral and integrodifferential equations are presented. For a strip parallel or perpendicular to the interface, a circular cylinder, and a rectangular cylinder, data are presented and discussed for selected parameters, including the case of a cylinder resting on the interface.     

Current induced on a conducting cylinder located near the planar interface between two semi-infinite half-spaces

An analysis is described for determining the current induced by a known excitation on a conducting cylinder located near the planar interface between two semi-infinite, homogeneous half-spaces of different electromagnetic properties. The perfectly conducting cylinder of general cross section is of infinite extent and the excitation is transverse magnetic to the cylinder axis. An integral equations for the induced current is derived and a numerical method for solving it is developed. The kernel of the integral equation contains a term corresponding to the usual open-space Green's function plus a term proportional to a Sommerfeld-type integral in two dimensions. Various forms of the Sommerfeld-type integral are given and the choices of form amenable to efficient evaluation are discussed. For a flat strip, a circular cylinder, and a rectangular cylinder, data are presented and discussed for selected parameters. Data are presented for cylinders above and below the interface as well as for a cylinder resting on the interface.     

Current induced on a conducting strip which resides on the planar interface between two semi-infinite half-spaces

An analysis is described for determining the current induced by a known excitation on a conducting strip which resides on the planar interface between two semi-infinite homogeneous half-spaces of different electromagnetic properties. The perfectly conducting flat strip is of infinite extent and the excitation is transverse magnetic to the strip axis. An integral equation for the induced current is formulated and it is shown that its kernel which is in general a Sommerfeld-type integral can be expressed in closed form when the permeabilities of the two media are the same. Under this practical condition the integral equation is solved numerically and data are presented for cases of interest. For the electrically narrow strip, the integral equation is approximated and this approximate equation is solved analytically.     

Scattering of electromagnetic waves by a metal lattice placed at the interface of two media

Simple formulas for determination of components of the scattering matrix of a plane electromagnetic wave incident along the normal onto a thin infinite 2D metal lattice with square windows placed at the interface of two media are derived for the first time. Frequency responses (FRs) of this structure calculated with the use of these formulas agree well with responses obtained by the numerical electromagnetic analysis of a 3D model in the case when the lattice period is less than one-half of the wavelength. The capability of efficient control of the FR of the analyzed structure by means of variation in the width of conductors and the lattice period enables application of this lattice for fabrication of a reflector with prescribed reflectivity. Such reflectors at interfaces of dielectric layers are required, for example, in the design of multilayer sufaces radio transparent in a specified frequency band or optical bandpass filters.     

Determination of potential at the beveled interface between two materials

A numerical method is described to compute the electrostatic potential at the beveled interface between two different materials by solving the two-dimensional Poisson's equation. The bevel angles are discretized in such a manner that an exact expression for the normal component of the electric field can be used. Curved interfaces can be treated. This method has been employed to calculate the potential distribution in a power VMOS device.     

Nonlinear surface waves on the interface of two non-Kerr-likenonlinear media

In recent years, there has been growing interest in studying nonlinear guided-wave propagation as they present potential, yet not fully-explored, applications for high-speed optical signal processing and transmission. In this paper, analytical solutions for nonlinear surface waves on the interface of two nonlinear non-Kerr-like media are derived. The dispersion relations and their relations to the transmission power and initial field distributions are calculated. Several observations are made on the behaviors of the surface waves and their potential applications     

非线性负折射率材料表面TE电磁波的空间稳定特性分析

针对电磁波在正负非线性材料界面处的传播,研究了两种稳定状态下电磁波的物理特性。理论分析和数值计算表明,该界面处电磁波的传播存在着频率通带,且带宽仅与两种材料的固有属性有关。得出前向表面波和后向表面波均可以在这种非线性导波系统中传播,并且在一定条件下,随着频率的变化,前向表面波和后向表面波可以在两种材料中跃变。推论出两种稳定传播的电磁波场峰值位置随传播功率的变化也能实现在两种材料中跃变,并逐渐向界面靠近,而传播功率较大的稳定态电场峰值几乎靠着界面。     

New results for the effective propagation constants of nonuniform plane waves at the planar interface of two lossy media

This paper presents a correction and a generalization of the solution presented previously (for original papers see R. D. Radcliff and C. A. Balams, "Modified propagation constants for nonuniform plane wave transmission through conducting media," IEEE Transactions in Geoscience Remote Sensing, vol. GE-20, no. 3, p. 408-411 (1982) and C. A. Balams, Advanced Engineering Electromagnetics, New York: Wiley (1989)) for the effective propagation constants of nonuniform plane waves at the planar interface of two isotropic homogeneous possibly lossy media of infinite transverse dimensions.     

FDTD simulation of TE and TM plane waves at nonzero incidence in arbitrary Layered media

Plane wave scattering is an important class of electromagnetic problems that is surprisingly difficult to model with the two-dimensional finite-difference time-domain (FDTD) method if the direction of propagation is not parallel to one of the grid axes. In particular, infinite plane wave interaction with dispersive half-spaces or layers must include careful modeling of the incident field. By using the plane wave solutions of Maxwell's equations to eliminate the transverse field dependence, a modified set of curl equations is derived which can model a "slice" of an oblique plane wave along grid axes. The resulting equations may be used as edge conditions on an FDTD grid. These edge conditions represent the only known way to accurately propagate plane wave pulses into a frequency dependent medium. An examination of grid dispersion between the plane wave and the modeled slice reveals good agreement. Application to arbitrary dispersive media is straightforward for the transverse magnetic (TM) case, but requires the use of an auxiliary equation for the transverse electric case, which increases complexity. In the latter case, a simplified approach, based on formulating the dual of the TM equations, is shown to be quite effective. The strength of the developed approach is illustrated with a comparison with the conventional simulation based on an analytic incident wave specification with half-space, single frequency reflection and transmission for the edges. Finally, an example of a possible biomedical application is given and the implementation of the method in the perfectly matched layer region is discussed.     

Mathematical simulation of characteristics of angular coordinate estimates of radar targets in the vicinity of interface between two media

The calculations, used for investigating the characteristics of measurement of radar targets’ angular coordinates near the interface between two media, are based on mathematical models set up as superposition (in the observation point) of two waves reflected from the object: the direct wave and the wave reflected by the surface of the interface between two media. These mathematical models are shown to be convenient and efficient for inquiries in characteristics of amplitude algorithms of measurements. The models agree well with the results of target’s elevation measurement, obtained during full-scale tests.     

On the stability of the FDTD algorithm for elastic media at amaterial interface

In this paper, the stability behavior of the first-order finite-difference time-domain algorithm for elastodynamics at the interface between two different materials is investigated. A necessary condition for stability is established, which, dependent on the material properties of the two media, might be more restrictive than the well-known Courant condition. It is shown that this more restrictive stability condition can be avoided if the material properties are averaged on the boundary     

Conductivity measurements at the interface between the sinteredconductor and dielectric substrate at microwave frequencies

A novel measuring technique of the effective conductivity at microwave frequencies for both the sintered conductor surface and the interface between conductor and dielectric materials was developed. In the measurement, a dielectric rod resonator is placed between two dielectric plates, one side of which is coated with a sintered conductor. For measuring the surface conductivity, the dielectric rod is sandwiched by the conductor side of the plates. On the other hand, for measuring the interface conductivity, the dielectric rod is sandwiched by the dielectric side of the plates. By the configuration, only interface conductivity contributes to the conducting loss of the resonator, thus allowing the measurement of the interface conductivity. Using the new technique, the frequency dependence of both the surface and interface conductivity of a sintered copper, formed on a glass ceramic substrate by the co-firing technique, was investigated in the frequency range from 11 to 34 GHz. It was confirmed that the values of interface conductivity of the sintered copper were smaller than the values of the surface conductivity     

Anomalous microstructure formed at the interface between copper ribbon and tin-deposited copper plate by ultrasonic bonding

The present paper reports an anomalous microstructure formed at interfaces between Cu ribbons and Sn-deposited Cu plates by ultrasonic bonding. The interface consists of Cu-to-Cu directly bonded part and Sn-dispersed part. In the latter part, Sn is dispersed in the vicinity of the bond interfaces being retained as Sn. The formation process of the interfacial microstructure is discussed on the basis of detailed experimental analysis and theoretical analysis on the solid-state reaction at Cu/Sn interface. The theoretical analysis reveals three important points of the reaction. (1) The formation of Cu₆Sn₅ precedes that of Cu₃Sn. (2) The incubation time for the formation of Cu₆Sn₅ changes discontinuously at the η/η′ transition temperature. (3) The incubation time for the formation of η′Cu₆Sn₅ is longer than that for ηCu₆Sn₅.     

Surface waves at a plane interface between vacuum and plasma with the magnetostatic field normal to the interface

The characteristics of the surface waves sustained by a plane interface which separates semi-infinite regions of vacuum and magnetoionic medium are investigated for the case in which the magnetostatic field is normal to the interface. It is found that plane surface waves exist if the gyromagnetic frequency is less than the plasma frequency and in the range of frequencies lying between the gyromagnetic frequency and1/sqrt{2}times the upper hybrid resonant frequency. The phase velocity of the surface waves is always less than the velocity of electromagnetic waves in free space, and it decreases monotonically with the increase in the frequency and goes to zero at1/sqrt{2}times the upper hybrid resonant frequency.     

Exact image theory for the calculation of fields transmitted through a planar interface of two media

Exact image theory, recently developed for the calculation of fields reflected from a planar interface between two homogenous media, is extended for transmitted field calculation. The image of a point source is found to be a line source located in complex space for proper convergence. Unlike for the reflection image, the transmission image line is seen to be curved in complex space for efficient computation. Expressions are derived for the transmission image of the most general three-dimensional electric and magnetic sources and for media with bothepsilonandmudiscontinuous across the interface. The new theory is verified with several asymptotic tests and properties of the transmission image function are discussed. As an application, radiation from a resonant horizontal loop antenna into the ground is calculated and results are seen to agree with those given in the literature.     

Exact radiation for dipoles on metallic spheroids at the interface between isorefractive half-spaces

Oblate and prolate metallic spheroids located at the interface between isorefractive half-spaces are considered. The electromagnetic fields produced by electric and magnetic dipoles located on the symmetry axis of the structure are determined exactly. Particular cases are discussed, and numerical results are presented for far fields and surface currents.     

Intermetallic compounds formed at the interface between liquid indium and copper substrates

The interfacial reactions between liquid In and Cu substrates at temperatures ranging from 175°C to 400°C are investigated for the applications in bonding recycled sputtering targets to their backing plates. Experimental results show that a scallop-shaped Cu₁₆In₉ intermetallic compound is found at the Cu/In interface after solder reactions at temperatures above 300°C. A double-layer structure of intermetallic compounds containing scallop-shaped Cu₁₁In₉ and continuous CuIn is observed after the Cu/In interfacial reaction at temperatures below 300°C. The growth of all these intermetallic compounds follows the parabolic law, which implies that the growth is diffusion-controlled. The activation energies for the growth of Cu₁₆In₉, Cu₁₁In₉, and CuIn intermetallic compounds calculated from the Arrhenius plot of growth reaction constants are 59.5, 16.9, and 23.5 kJ/mole, respectively.     

Interaction of two different frequency photonic crystal waveguide modes through the resonant excitation of modes on off-channel Kerr nonlinear media

The properties of two photonic crystal waveguide modes at different frequencies that propagate down a straight photonic crystal waveguide are studied for cases in which the two modes interact with off-channel structures composed of Kerr nonlinear dielectric media. The optical nonlinearity of the off-channel structures mediates an interaction between the two modes that allows the modes to modulate the transmission of each other down the waveguide channel. This interaction and mutual modulation is shown to be pronounced in the case when either of the two waveguide modes resonantly excites a localized mode on the off-channel features formed of Kerr nonlinear media. Cases that are considered are a straight linear dielectric media waveguide with off-channel structures formed as: (a) a single off-channel Kerr site that supports a bound localized electromagnetic mode, (b) multiple off-channel Kerr sites that support a bound intrinsic localized electromagnetic mode, and (c) multiple off-channel Kerr sites that support an intrinsic localized mode that in turn interacts with a semi-infinite waveguide of linear dielectric media. In cases (a) and (b) the effects of resonant excitation of single site and intrinsic localized modes in the Kerr medium on the transmission characteristics are determined. In case (c) the effects of resonant excitation of intrinsic localized modes in the Kerr medium on the transmission characteristics of the two waveguide modes into the infinite and semi-infinite waveguides are studied.