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.<>     

Propagating eigenmodes for plane waves in a uniaxial bianisotropicmedium and reflection from a planar interface

A time-harmonic electromagnetic plane wave propagating in a uniaxial bianisotropic medium is considered. Forward- and backward-propagating eigenmodes are identified, together with their dispersion equations. The eigenmodes consist of two pairs with different phase velocities, and the two components of each pair correspond to the forward and backward modes. The propagating modes are used to calculate the reflection coefficient matrix at an interface between a vacuum and a uniaxial bianisotropic half-space. Numerical results for such a reflection are presented as a function of the direction of the optical axis     

Uniaxial chiral quarter-wave polarisation transformer

The uniaxial chiral medium is a generalisation of the well-studied isotropic chiral media. It is obtained when microscopic helices with parallel axes are positioned in a host dielectric in random locations. Solutions for the dispersion equation and for the eigenwaves for a uniaxial chiral medium were recently found. Here the authors consider the polarisation properties of a transverse wave propagating through a uniaxial chiral slab. The results give a simple possibility for constructing a polarisation transformer for changing the polarisation of a propagating plane wave.<>     

Modeling of transverse propagation through a uniaxial bianisotropic medium using the finite-difference time-domain technique

This work presents an extension of the recently developed finite-difference time-domain (FDTD) technique for modeling electromagnetic wave interactions with bianisotropic (BI) media, known as BI-FDTD, to include the more general class of bianisotropic materials. This new FDTD formulation is called BA-FDTD. The theoretical foundation for this method is based on a wavefield decomposition technique. The formulations based on the application of this wavefield decomposition technique to BA media will be presented. Validations of this new model are demonstrated for the interaction of an electromagnetic wave propagating transversely through a uniaxial BA half-space.     

Green dyadic for a uniaxial bianisotropic medium

An explicit expression for the Green dyadic corresponding to the axially chiral reciprocal uniaxial bianisotropic medium is derived through dyadic analysis with no recourse to Fourier transformations. The result is a generalization of the Green dyadic corresponding to the uniaxial anisotropic medium, which has been known for decades. As a verification, expressions for the field due to an axial dipole are derived and compared to those derived recently through other methods. The medium under study can be realized by laying axially parallel metal helixes in random locations in a host material. Such a medium has recently been shown to possess important polarization-transforming properties     

Reflection and transmission of electromagnetic plane waves from an uniaxial chiro-omega slab

Chiro-omega medium is a combination of the reciprocal chiral and omega media, and can be obtained by mixing helical and Ω — shaped wire elements in the host medium. In this article the most general uniaxial chiro-omega medium is studied. The solutions for the dispersion equations and corresponding eigenwaves are derived. Transmission and reflection properties of a chiro-omega slab at a normal incidence are studied, and the polarization, direction of the polarization ellipse, and relative powers of transmitted and reflected waves are given. The results are applied to find suitable parameters for designing a polarization transformer. These results are compared with those obtained in earlier studies on wave propagation in a free uniaxial chiral space, where the effect of the boundaries of a proposed polarization transforming device have been neglected.     

多层单轴手征类复合材料中的双重手征结构和特性

应用广义谱域指数矩阵技术，研究具有双重手征性结构的多层单轴复合手征介质层对任意极化入射平面电磁波的反射和透射特性。用数值方法分析了光轴取向、损耗、手征和非互易参数对反射和透射系数的影响。特别是交叉极化转换效应。结果表明，双各向异性单轴手征介质在新型模式极化转换器的研制等方面有重要的应用价值。     

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.

     

Wave reflections from a conducting surface with a moving uniaxial sheath

The behavior of a plane wave incident from an isotropic medium onto a perfectly conducting plane covered with a moving uniaxial sheath is studied in detail. The governing equations are formulated by making use of the transformed constitutive relations of the moving sheath viewed as a stationary bianisotropic medium. The dispersion equations for the ordinary and extraordinary components of the wavenumber in the moving sheath are then obtained. Complete field expressions for both the reflected wave and the wave in the moving medium are given in terms of the longitudinal field components of the incident wave for an arbitrary orientation of the plane of incidence and an arbitrary angle of incidence. Several special cases are considered and some interesting numerical results are presented in graphical form.     

Ie transmission properties of stratified chiroferrite media with obliquely incident plane wave

A parameter study of electromagnetic wave propagating through the air-chiro ferrite inter face and through a chiro ferrite slab is presented, and such bianisotropic medium can be made from chiral and gyrotropic ferrite materials artifically. The partial differential equations of the fourth order defining the field components E_y and H_y in chiroferrite are derived. The influence of different constitutive parameters on the transmission coefficients and refraction angles of transmitted fields are demonstrated. The results show that chirality causes strong effect of energy conversion between mode 1 and 2.     

Plane-wave reflection from uniaxial chiral interface and itsapplication to polarization transformation

Plane-wave reflection and transmission in a planar interface between air and an axially chiral uniaxial medium whose axis is parallel to the interface is considered in the present study. By finding the reflection dyadic and its eigensolutions, we demonstrate that by dimensioning the uniaxial medium in a proper way, it is possible to make a reflection-transforming reflecting surface. The surface is able to transform the incident linear polarization into any other polarization with chosen axial ratio and handedness, and the reflected polarization can be continuously adjusted by rotating the surface around its normal direction. The reflected power is seen to be independent of the polarization of the reflected wave     

On Anomalous Propagation in Axially Uniaxial Bianisotropic Mediums

Propagation of a plane electromagnetic wave in axially uniaxial bianisotropic mediums (AUBMs) is investigated. It is shown that anomalous behaviour arises when a certain condition is fulfilled by the constitutive parameters of the medium.     

On Anomalous Propagation in Transversely Uniaxial Bianisotropic Mediums

We consider the propagation of a plane electromagnetic wave in transversely uniaxial bianisotropic mediums (TUBMS). Anomalous propagation takes place when a certain condition is fulfilled by the constitutive parameters of the medium. A detailed field analysis for this anomalous behaviour is provided.     

Equivalent circuit representation of anisotropic media and chiral media and its application in polarization transformations

This work presents a new viewpoint to study polarization transformations. This concept is more convenient when dealing with polarization transformation problems in multiple layers. The anisotropic medium and the chiral medium can be regarded as circuit elements. Specifically, we show that anisotropic media can be seen as transformers and chiral media as transmission lines. Once the equivalent circuits are determined, the microwave network theory can be used to investigate the polarization transformation. An example is used to demonstrate the transformation from the horizontally polarized wave to the circularly polarized wave employing the equivalent circuit concept.     

Eigenvalues and eigenvectors of general gyroelectric media

Explicit and relatively simple expressions for eigenvalues and guided (propagating) eigenvectors of a general gyroelectric medium, where the preferred guided wave direction, zˆ, is parallel to the gyrotropic axis and anisotropy is confined to a plane transverse to z, are given. Some special cases of interest, namely, Hermitian, symmetric (biaxial), and uniaxial permittivity tensors, are also considered. The natural, or optic, coordinate basis is used to derive the source-free eigenvectors and to explicitly reveal the polarization states of those eigenvectors. Also under this basis, the evolution of eigenvalues and eigenvectors as off-diagonal terms of the permittivity tensor uniformly vanish, a transition from the biaxial to the uniaxial case, is discussed     

The electric quadrupole contribution to the circular birefringenceof nonmagnetic anisotropic chiral media: a circular waveguide experiment

Constitutive relations which include electric quadrupole terms, in addition to electric and magnetic dipole terms, are used to describe the “optical activity”, in particular the circular birefringence, of an anisotropic chiral medium which is nonmagnetic. The resulting permittivity and chirality tensors are then used to predict the rotation of the polarization plane of a linearly polarized wave propagating in a circular waveguide filled with the medium. The numerical predictions were tested by measurements between 2.4 and 4 GHz on a 2 m long artificial crystal in a circular waveguide and it was found that the rotation of the polarization was within 13% of the predicted value-good agreement after considering the possible sources of error. It is thus established that the effect of electric quadrupoles must be included when modeling the optical activity of anisotropic chiral media in the long wavelength regime. The anisotropic chiral media which are dealt with here can be classified according to the crystallographic point groups to which they belong, and they may therefore also be considered to be artificial crystals     

Polarization transformation of a wave field propagating in ananisotropic medium

The momentous experimental discovery of the Faraday (1846) effect is sketched from a historical perspective, through the eyes of several well-known scientists. This effect and its generalization can be explained theoretically by using the dispersion theory for waves propagating in an anisotropic medium. A wave of arbitrary initial polarization will have its wave polarization transformed continuously as it propagates. It is convenient to represent this continuous polarization transformation by a locus in the polarization-ratio plane. In a lossless medium, when both characteristic waves are propagating, this locus is a circle. Five cases in a magneto-ionic medium have been investigated for different propagation angles. The results are discussed and illustrated     

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.     

Time-harmonic two- and three-dimensional Green's dyadics forgeneral uniaxial bianisotropic media

A rigorous study of the Green's dyadics in two and three dimensions for general uniaxial bianisotropic media is made. The Green's dyadics are derived in the time-harmonic regime. A general uniaxial bianisotropic medium is described by eight parameters. In general, it is impossible to derive a closed-form representation of the Green's dyadics in three dimensions. In one important special case, however, where one relation is satisfied between the eight parameters, it is possible to obtain a closed-form representation     

Plane Waves Propagating in Chiral Plasma and Chiral Ferrite Media

Plane wave propagation in chiral plasma and chiral ferrite media is studied in kDB coordinate system. General wave equations and characteristic equations of plane waves propagating along an arbitrary direction in chiral plasma and in chiral ferrites are derived in simple formulations respectively. Four wavenumbers and their corresponding dispersion characteristics are resulted for propagation both along and normal to the biasing magnetic field. When plane wave with negative helicity propagates along the biasing magnetic field in chiral ferrites, backward waves emerge. However backward waves occur with both positive and negative helicities when propagating along the biasing magnetic field in chiral plasma.