Uniaxial Bianisotropic Medium Research Articles

Effects of Uniaxial Bianisotropic Media on Full-Polarimetric GPR Signatures

The polarimetric response of full-polarimetric ground penetrating radar (FP-GPR) from anisotropic media is a pressing issue to be investigated. It can improve the detection accuracy of the targets in the anisotropic media and can also provide effective ways to detect anisotropic targets. In this paper, we focus on the FP-GPR signals from uniaxial bi-anisotropic media, i.e. the complete case that both the permittivity and the conductivity of the background media are anisotropic. Based on the propagation characteristics of electromagnetic waves in the anisotropic media and the transmission coefficients on the surface of the media, we construct a mathematical relation between the measured scattering matrix affected by anisotropies and the real scattering matrix, derive a coefficient to characterize the polarization rotation(PR) effects, and proposed a diagonal matrix for target decomposition analyses. The computation results indicate that ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>z</i></sub> /ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> , σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>z</i></sub> /σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> , and antenna interval have complex effects on the PR coefficient and the H-Alpha decomposition results of three types of typical targets. Multiple 3D FP-GPR simulations on a series of uniaxial bi-anisotropic models verified the results.

Spectral shifts in the properties of a periodic multilayered stack due to isotropic chiral layers

Investigating the canonical problem of a periodic multilayered stack containing isotropic chiral layers, we homogenized it as a uniaxial bi-anisotropic medium and derived its effective constitutive parameters. The stack shows a resonant behaviour, when its unit cell consists of a metallic layer and an isotropic chiral layer. The presence of isotropic chirality can result in small shifts of the resonance frequency for reasonably large values of the chirality parameter, implying that the sign of an effective permittivity can be switched. Such spectral shifts in the dielectric properties can be potentially useful for spectroscopic purposes.

Electromagnetic wave propagation in rectangular waveguides filled with Omega-medium

A time-harmonic electromagnetic plane wave propagating in a uniaxial bianisotropic medium, the so-called Omega medium, is considered. Plane waves are identified together with their dispersion equations with the help of an appropriate coordinate system. The plane wave solution is then used to study in a rigorous way the coupled-mode equations satisfied by the electromagnetic field in a rectangular waveguide filled with such a material and bounded by perfect electrically conducting walls. The features of this approach are demonstrated and an application to rectangular waveguides is discussed. Numerical results are also presented as a function of the material parameters.

Electromagnetic Scattering by a Multilayer Gyrotropic Bianisotropic Circular Cylinder

In this paper, we investigate the electromagnetic scattering by a multilayer gyrotropic bianisotropic circular cylinder in free space. The coupled wave equations of longitudinal field components in the gyrotropic bianisotropic medium are derived. The eigenfunction expansion method is used to solve the scattering problem after uncoupling the coupled wave equations. A 12 × 12 or 16 × 16 linear algebraic equation is solved for two cases: one with the center being a perfect electric conducting (PEC) cylinder; and one without the PEC center, respectively. The gyrotropic bianisotropic media can be degenerated into gyrotropic medium, uniaxial bianisotropic medium, biisotropic medium and chiral medium etc. Numerical results presented for the last case was shown to agree exactly with published results. Numerical results of electromagnetic scattering by gyrotropic bianisotropic circular cylinders are presented also.

ELECTROMAGNETIC SCATTERING BY A MULTILAYER GYROTROPIC BIANISOTROPIC CIRCULAR CYLINDER - Abstract

In this paper, we investigate the electromagnetic scattering by a multilayer gyrotropic bianisotropic circular cylinder in free space. The coupled wave equations of longitudinal field components in the gyrotropic bianisotropic medium are derived. The eigenfunction expansion method is used to solve the scattering problem after uncoupling the coupled wave equations. A 12 × 12 or 16 × 16 linear algebraic equation is solved for two cases: one with the center being a perfect electric conducting (PEC) cylinder; and one without the PEC center, respectively. The gyrotropic bianisotropic media can be degenerated into gyrotropic medium, uniaxial bianisotropic medium, biisotropic medium and chiral medium etc. Numerical results presented for the last case was shown to agree exactly with published results. Numerical results of electromagnetic scattering by gyrotropic bianisotropic circular cylinders are presented also.

THE THEORY OF UNIAXIAL BI-ANISOTROPIC MEDIA: THE QUASI-STATIC CASE

The problem of unbounded uniaxial bi-anisotropic media in the presence of both static electric and magnetic point charges is investigated. For this purpose scalar electric and magnetic potentials in these media are introduced. Using these potentials, the corresponding electric and magnetic fields are then determined. The similar problem of static electric and magnetic current sources with the goal of finding the electromagnetic fields is carried out. It is observed that either of static electric or magnetic point charge produces both electric and magnetic fields. Furthermore, it is observed that only the transverse components of current sources with respect to axis of the medium produce the axial field components.

Vector wave function expansions of dyadic Green's functions for bianisotropic media

An alternative set of Cartesian vector wave functions is presented to simplify the development of eigenfunction expansions of electromagnetic fields and dyadic Green&apos;s functions for bianisotropic media. With the eigenfields expanded using these functions, the determination of their expansion coefficients is facilitated via a concise 4×4 matrix method. Based on the complete dyadic discontinuity relations, the source consequents of dyadic Green&apos;s functions are also explicitly expressed in terms of these functions. By incorporating the modified reciprocity theorem into the discontinuity relations, more compact source consequents are found to be related directly to the eigenfields in a complementary medium. These complementary eigenfields, in turn, can be deduced readily from their original counterparts by performing certain simple transformations. This manner of incorporating reciprocity provides a clear insight into the significance of each discontinuity relation and reveals the connections between the singularities, discontinuities and the complementary eigenfield components. For illustration, the vector wave functions expansions of the eigenfields for isotropic and uniaxial bianisotropic media are discussed.

Cylindrical vector wave function representation of Green's dyadics for uniaxial bianisotropic media

This paper presents a novel and rigorous eigenfunction expansion of electric‐type dyadic Green's function for an unbounded uniaxial bianisotropic medium in terms of the cylindrical vector wave functions. The Green's dyadic is obtained on the basis of the well‐known Ohm‐Rayleigh method together with some newly developed vector and tensor identities formed by the differential, curl, and dot product of the constitutive dyadics and the cylindrical vector wave functions. The above identities greatly simplify the process of finding the vector expansion coefficients of the dyadic Green's function of the uniaxial bianisotropic media. The dyadic Green's function derived is expressed in terms of the contribution from the irrotational solenoidal types of vector wave functions, with the λ integrals removed using the residue theorem.

Conditions for the parameter dyadics of lossy bianisotropic media

AbstractConditions for the parameter dyadics are derived for bianisotropic media to be lossy (power absorbing). The conditions, which can be expressed easily in terms of the 6×6 matrix of four parameter dyadics as being Hermitian and negative definite, are brought to the level of individual parameter dyadics as four separate dyadic conditions. The theory is applied to three particular medium classes: bi‐isotropic media, uniaxial bianisotropic media, and gyrotropic bianisotropic media as a set of inequalities for the scalar parameters. The conditions are needed for judging the physical realizability of parameter values of new composite media. © 2001 John Wiley &amp; Sons, Inc. Microwave Opt Technol Lett 29: 175–178, 2001.

Uniqueness in a frequency-domain inverse problem of a stratified uniaxial bianisotropic medium

An inverse problem for a stratified uniaxial bianisotropic slab is considered in the frequency domain. The problem is treated as an analytic factorization problem in the frequency complex plane. Uniqueness in the parameter reconstruction is discussed and illustrated under a particular choice of a priori information.

Electromagnetic scattering by a reciprocal uniaxial bianisotropic cylinder with arbitrary cross section: extended mode-matching method

Based on the eigenfunction expansion of electromagnetic waves in a reciprocal uniaxial bianisotropic medium, an extended mode-matching method is proposed to study the scattering of an infinitely long reciprocal uniaxial bianisotropic cylinder with arbitrary cross section. Excellent convergence of the echo width is numerically verified, which establishes the reliability and applicability of the present extended mode-matching method for the two-dimensional single-body problem in which the reciprocal uniaxial bianisotropic medium has a curved surface.

Scattering from a reciprocal uniaxial bianisotropic circular cylinder in the proximity of a perfect electric conductor plane

Based on the image theory of a bianisotropic object and the cylindrical vector wave functions in conjunction with their addition theorem, a convenient and effective technique is developed to study electromagnetic scattering by a reciprocal uniaxial bianisotropic circular cylinder in the proximity of a perfect electric conductor plane. Numerical results of the bistatic and the backward echo widths for TMz and TEz incident plane waves, respectively, are presented. As a result of the linear magnetoelectric interaction effects of the reciprocal uniaxial bianisotropic medium, polarization transformation of the scattered wave occurs.

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

The Green's dyadics are derived for a new combined nonreciprocal and uniaxial bi-anisotropic medium with material dyadics of the form /spl mu//sup =//spl alpha//spl epsiv//sup =T/, /spl xi/u/sup =/=/spl xi/u/sub z/u/sub z/, and /spl zeta//sup =/=/spl zeta/u/sub z/u/sub 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 an axially uniaxial bianisotropic medium

Novel expressions for the depolarization dyadics in an axially uniaxial bianisotropic medium (AUBM) are presented. Explicit formulae for the depolarization dyadics are derived for cubical, cylindrical and spherical geometries and their dependence on the magnetoelectric coupling parameter is studied graphically.

Scattering From a Perfect Electric Conductor (Pec) Cylinder With an Inhomogeneous Coating Thickness of Reciprocal Uniaxial Bianisotropic Medium

Based on the eigenfunction expansion of electromagnetic waves in the reciprocal uniaxial bianisotropic medium, an extended mode-matching method is developed to study the electromagnetic scattering of a PEC circular cylinder with an inhomogeneous coating thickness of reciprocal uniaxial bianisotropic medium. Excellent convergence property of the bistatic echo width is numerically verified, which establishes the reliability and applicability of the present extended mode-matching method for two-dimensional problem of reciprocal uniaxial bianisotropic medium.

Source-Region Electric and Magnetic Fields in an Uniaxial Bianisotropic Medium

ABSTRACT We use the Fikioris approach to delineate the singular behaviours of time-harmonic electric and magnetic fields in a homogeneous, reciprocal, axially uniaxial bianisotropic medium (AUBM), thereby extending results previously obtained for a uniaxial dielectric-magnetic medium. Electrically small source regions of arbitrary convex shape are given special attention, and a simple expression for the depolarization dyadic pertaining to spherical geometry is presented. Scattering by electrically small objects and the homogenization of particulate composites provide the main applications of our results.

Decomposition of Electromagnetic Fields in Bi-Anisotropic Media

Electromagnetic-field TE/TM decomposition theory, well known for fields in isotropic and uniaxially anisotropic media and their extension to uniaxial bi-anisotropic media is generalized to cover all bi-anisotropic media. General conditions for the medium parameter dyadics are derived for the decomposition to be possible. Some decomposable special bi-anisotropic media are considered as examples of applying the general conditions. Previously known cases are seen to fall under the conditions derived. The decomposition theory can be applied to splitting an electromagnetic problem in two simpler problems.

Field representations in reciprocal uniaxial bianisotropic media by cylindrical vector wave functions

Field representations in reciprocal uniaxial bianisotropic media by cylindrical vector wave functions

Field representations in reciprocal uniaxial bianisotropic media by cylindrical vector wave functions

Reciprocal uniaxial bianisotropic media are generalizations of the well-studied chiral materials. Based on the concept of characteristic waves and the method of angular spectral expansion, field representations in this class of media are developed in terms of the cylindrical vector wave functions. An additional theorem of vector wave functions for reciprocal bianisotropic medium can be derived from that for isotropic media. Application of the present formulations in scattering is presented to show how to use these formulations in a practical way. © 1996 John Wiley & Sons, Inc.

Green dyadics in reciprocal uniaxial bianisotropic media by cylindrical vector wave functions.

The reciprocal uniaxial bianisotropic medium, which can be fabricated by polymer synthesis techniques, is a generalization of the well-studied chiral medium. It has potential applications in the design of antireflection coating, antenna radomes, and interesting microwave components. In the present investigation, based on the concept of spectral eigenwaves, eigenfunction expansion of the Green dyadics in this class of materials is formulated in terms of cylindrical vector wave functions. The formulations are greatly simplified by analytically evaluating the integrals with respect to the spectral longitudinal and radial wave numbers, respectively. The analysis indicates that the solutions of the source-incorporated Maxwell's equations for a homogeneous reciprocal uniaxial bianisotropic medium are composed of two eigenwaves traveling with different wave numbers, and each of these eigenwaves is a superposition of two transverse waves and a longitudinal wave. The Green dyadics of planarly and cylindrically multilayered structures consisting of the reciprocal uniaxial bianisotropic media can be straightforwardly obtained by applying the method of scattering superposition and appropriate electromagnetic boundary conditions, respectively. The resulting formulations, which can be theoretically verified by comparing their special forms with existing results, provide a fundamental basis to analyze and understand the physical phenomena of unbounded and multilayered reciprocal uniaxial bianisotropic media. The method employed here can be generalized to derive the eigenfunction expansion of Green dyadics in other kinds of media. \textcopyright{} 1996 The American Physical Society.