Spectral dyadic Green's function formulation for uniaxial bianisotropic superstrate-substrate structure

In this paper, spectral-domain dyadic Green's functions for the time harmonic electric current source embedded in a two-layer grounded uniaxial bianisotropic media are obtained using Fourier tranform. It is shown that in the uniaxial bianisotropic medium, total spectral electromagnetic field can also be separated into the superposition of transverse electric (TE) and transverse magnetic (TM) wave. Because of the generality of constitutive relations our results include the special cases of achiral, uniaxial, reciprocal and nonreciprocal biisotropic media.

     

Closed-form Green's dyadics for a class of media with axialbi-anisotropy

The Green's dyadics are derived for a new combined nonreciprocal and uniaxial bi-anisotropic medium with material dyadics of the form μ⁼αϵ^=T, ξu⁼=ξu_zu_z, and ζ⁼=ζu_zu_z. The result can be expressed as an infinite series of exponential integrals. It is investigated for which media this series truncates to a closed-form expression and the result is checked with known Green's dyadics for special cases of the medium parameters     

New expressions for depolarization dyadics in uniaxial dielectric-magnetic media

We present some novel expressions for the depolarization dyadics in uniaxial dielectric-magnetic media. These expressions were obtained by generalizing the Fikioris approach for extracting the singular behaviour of integrals involving the dyadic Green functions and the source current density distributions. Cubical, cylindrical and spherical geometries serve as examples for a discussion of the depolarization dyadics' dependence on geometry and anisotropy.     

Relationships for Green's function spectral dyadics involvinganisotropic imperfect conductors embedded in layered anisotropic media

The Green's function spectral dyadic that characterizes a perfectly conducting patch antenna or propagating line can be modified to account for noninfinite conductivity. This is done through a relationship for a single planar interface imbedded in an anisotropic medium. A relationship for an arbitrary number of planar interfaces imbedded in an anisotropic medium is also derived. The imperfect conductor is represented by an anisotropic impedance     

Dipole radiation in uniaxial bianisotropic medium

Radiation from an electric dipole oriented parallel to the distinguished axis of a uniaxial bianisotropic medium is considered. The electromagnetic fields are represented in full generality in terms of two scalar Hertz potentials. An analytic solution for these scalar potentials is obtained.<>     

Plane wave propagation in uniaxial bianisotropic medium

The uniaxial bianisotropic medium is a generalisation of the bi-isotropic and chiral media which recently have been subject to intensive research. Such a medium results, for example, when microscopic helices with parallel axes are positioned in a host dielectric in random locations. Plane wave propagation in such a medium is studied and a simple solution for the dispersion equation is found. Numerical examples for the wave number surfaces of the medium are given.<>     

New theorems for bianisotropic media

The general volume equivalence theorem for bianisotropic scatterers is presented, where the equivalent electric and magnetic currents are determined by a pair of coupled vector integral equations. Moreover, using the general volume equivalence theorem and conventional image principle, image theory is developed for a bianisotropic body over an infinite perfect electric or magnetic conducting ground plane.     

Physically interpretable alternative to Green's dyadics, resultingrepresentation theorems, and integral equations

An alternative to the concept and use of Green's dyadics is presented. The major difference between the material presented here and the corresponding material usually presented with Green's dyadics stems from the use of a dipole source term instead of a unit dyadic source. Another difference is related to the fact that derivations employing Green's dyadics require that the dyadics satisfy a second-order curl curl equation. Here, the fields replacing the dyadics derive some of their attributes from solving Maxwell's first-order differential equations. Simple manipulations of Maxwell's first-order equations lead to the curl curl equation. What is accomplished is the derivation of equations that perform the same purposes as those requiring Green's dyadics but that are simpler and contain physically interpretable fields and surface currents in place of the dyadics. The details of how to derive totally equivalent representation theorems are presented, and the way to derive integral equations having the same benefit is outlined. Key results of this work are the representation theorems when the observation point is in the far zone of the reference surface. For this case, simple expressions are given in which plane-wave-excited currents on a perfect conductor replace Green's dyadics     

On the electromagnetic dyadic Green's functions for planar multi-layered anistropic uniaxial material media

A complete, plane-wave spectral, vector-wave function expansion of the electromagnetic, electric, and magnetic, dyadic Green's function for electric, as well as magnetic, point currents for a planar, anisotropic uniaxial multi-layered medium is presented. It is given in terms ofz-propagating, source-free vector-wave functions, where ? is normal to the interfaces, and it is developed via a utilization of the Lorentz reciprocity theorem. The electromagnetic dyadic Green's function for periodic electric as well as magnetic point current sources is also presented. Some salient features of the Green's dyadics, along with a physical interpretation are also described.     

Reflection and transmission of plane electromagnetic waves in uniaxial bianisotropic materials

Electromagnetic waves in the most general linear reciprocal uniaxial media are considered. The theory is appropriate for novel reciprocal microwave materials which have properties of chiral composites and omega structures (or both) and can be modeled by uniaxial bianisotropic constitutive relations. Field coupling terms in the media equations are assumed to be the most general uniaxial dyadics with symmetric and antisymmetric components. Plane eigenwaves in unbounded media are studied and the theory of reflection and transmission in plane layers is constructed.     

Nonseparable two- and three-dimensional wavelets

We present two- and three-dimensional nonseparable wavelets. They are obtained from discrete-time bases by iterating filter banks. We consider three sampling lattices: quincunx, separable by two in two dimensions, and FCO. The design methods are based either on cascade structures or on the McClellan transformation in the quincunx case. We give a few design examples. In particular, the first example of an orthonormal 2-D wavelet basis with symmetries is constructed     

单轴双各向异性媒质柱体的电磁散射

采用广义多极子技术（Ｇｅｎｅｒａｌｉｚｅｄ Ｍｕｌｔｉｐｏｌｅ Ｔｅｃｈｎｉｑｕｅ,ＧＭＴ）分析了单轴双各向异性媒质任意截面柱体的电磁散射,计算结果与解析解和矩量法（Ｍｅｔｈｏｄ ｏｆ Ｍｏｍｅｎｔｓ,ＭｏＭ）所得结果一致,讨论了该方法在电磁散射应用中的优缺点。     

Simple formulas for two- and three-dimensional capacitances

This paper proposes simple formulas for wiring capacitances in VLSI, including two- and/or three-dimensional effects. The accuracy of these formulas are practically sufficient for a wide range of wire thickness, wire width, and interwire spacing.     

Field decomposition and factorization of the Helmholtz determinantoperator for bianisotropic media

The paper generalizes the class of media for which the electromagnetic (EM) fields can be decomposed in two independent components. Each of the two components see the medium as a simpler, so called, equivalent medium. This generalization was possible because it was realized that the plane-wave fields satisfy E·D-H·B=0. This discovery allows us to come to a consistent structure for the class of decomposable and factorizable bianisotropic media encompassing all previously studied media as special cases. The class of media of the present paper is shown to be closed with respect to duality transformations. We dare to say that the present paper puts the crown on a long quest for always more general classes of media that allow decomposition and factorization. The equivalent media yield a new class of media that allow a closed form representation of the Green dyadics     

双各向异性色散介质电磁波传播Z-时域有限差分分析

基于一种改进的Z变换-时域有限差分(Z-Finite-Difference Time-Domain,Z-FDTD)方法,即将双各向异性色散介质的频域本构方程先转化到Z域中,再利用Z变换的性质将其转换到时域,得到离散时域的FDTD迭代式,分析了双各向异性色散介质电磁波传播特性.由于Omega媒质是一种典型的双各向异性色散介质,以此为例编程计算了垂直入射在Omega介质板情形下产生的同极化和交叉极化电磁波的反射和透射情况,并通过算例和解析解对比验证了算法的正确性,最后对其电磁散射特性进行了分析.     

Dyadic Green's function in bounded media

A new theory for the evaluation of the dyadic Green's functions in a homogeneous medium bounded by perfectly conducting walls is presented. The peculiarities of this theory are 1) the Green's functions are systematically and explicitly decomposed in a singular and an analytical part, and 2) these two parts are formulated in a general manner, i.e., independent on the boundaries. As an application, the Green's functions in a conical guide are evaluated.     

Reconstruction of two- and three-dimensional images from synthetic-collimator data

A novel SPECT collimation method, termed the synthetic collimator, is proposed. The synthetic collimator employs a multiple-pinhole aperture and a high-resolution detector. The problem of multiplexing, normally associated with multiple pinholes, is reduced by obtaining projections at a number of pinhole-detector distances. Projections with little multiplexing are collected at small pinhole-detector distances and high-resolution projections are collected at greater pinhole-detector distances. These projections are then reconstructed using the ML-EM algorithm. It is demonstrated through computer simulations that the synthetic collimator has superior resolution properties to a high-resolution parallel-beam (HRPB) collimator and a specially built ultra-high-resolution parallel-beam (UHRPB) collimator designed for our 0.38-mm pixel CdZnTe detectors. It is also shown that reconstructing images in three dimensions is superior to reconstructing them in two dimensions. The advantages of a high-resolution synthetic collimator over the parallel-hole collimators are apparently reduced in the presence of statistical noise. However, a high-sensitivity synthetic collimator was designed which again shows superior properties to the parallel-hole collimators. Finally, it is demonstrated that, for the cases studied, high-resolution detectors are necessary for the proper functionality of the synthetic collimator.     

二维和三维量子点量子比特的性质

在电子-体纵光学声子强耦合情况下, 我们采用Pekar类型的变分方法获得了二维和三维抛物势限制的量子点中的电子的基态和第一激发态的本征能量和本征波函数. 在量子点中这样的二能级体系可以作为一个量子比特. 当电子处于基态和第一激发态的叠加态时, 计算了电子态密度的时间演化。得出了电子的几率密度和振荡周期与电子-体纵光学声子耦合强度,量子点的限制长度的关系.     

Properties of the two- and three-dimensional quantum dot qubit

On the condition of electric-longitudinal-optical (LO) phonon strong coupling in both two- and threedimensional parabolic quantum dots (QDs),we obtain the eigenenergies of the ground state (GS) and the first excited state (ES),the eigenfunctions of the GS and the first ES by using a variational method of Pekar type.This system in QD may be employed as a quantum system-quantum bit (qubit).When the electron is in the superposition state of the GS and the first ES,we obtain the time evolution of the electron density.The relations of both the electron probability density and the period of oscillation with the electric-LO phonon coupling strength and confinement length are discussed.     

Recursive asymptotic impedance matrix method for electromagnetic waves in bianisotropic media

A recursive asymptotic impedance matrix method is presented for simple and stable analysis of electromagnetic waves in bianisotropic media. The method overcomes the numerical instability problem associated with the transition matrix method. It requires only elementary matrix operations along with thin-layer asymptotic approximation and bypasses the intricacies of the eigenvalue-eigenvector approach. Exploitation of its self-recursion algorithm with geometric subdivision of a layer leads to high computation efficiency. The method also facilitates the trade-off between accuracy and speed for various applications.