In this paper, a trial of probabilistic signal processing which is possible to give methodological suggestion to some quantitative measurement method of compound and/or ac-cumulation effect in electromagnetic (abbr. EM) environment is discussed. In order to extract various types of latent interrelation characteristics between many of waved environmental factors (EM and sound waves) leaked from VDT in a real working situation, some extended regression system model reflecting hierarchically not only linear correlation information of the lower order but also nonlinear correlation information of the higher order is firstly introduced. Especially, differing from the previous study, all regression parameters of this model are identified by positively utilizing information of a background EM noise instead of eliminating it. Then, some evaluation method for predicting a whole fluctuation distribution form from sound to EM is newly proposed. Finally, the validity and effectiveness of this proposed method are partly confirmed through some principle experiment too by applying it to the actually observed data leaked by a VDT playing some television games in the room of an actual working environment.

The inverse scattering of buried dielectric cylinders by transverse electric (TE) wave illumination is investigated. Dielectric cylinders of unknown permittivities are buried in one half space and scatter a group of unrelatedTE waves incident from another half space where the scattered field is recorded. By proper arrangement of the various unrelated incident fields, the difficulties of ill-posedness and nonlinearity are circumvented, and the permittivity distribution can be reconstructedthrough simple matrix operations. The algorithm is basedon the moment methodandthe unrelatedillumination method. Numerical results are given to demonstrate the capability of the inverse algorithm. Goodreconstruction is obtainedev en in the presence of additive random noise in measured data. In addition, the effect of noise on the reconstruction result is also investigated.

In this paper, the radiation characteristics of an open circular waveguide asymmetrically covered by a layered dielectric hemi-spherical radome are analyzed. On the waveguide opening, the dominant TE11 wave of the circular waveguide is assumed. The technique of dyadic Green's function is applied to obtain the radiated electromagnetic fields due the circular aperture. Huygens' equivalence principle and the image theory are utilized to simplify the problem. The translational addition theorems of spherical vector wave functions are also employed to make the mathematical representation of the radiated fields compact. Both the exact formulation in the near (radiating-field) zone and the approximate expressions in the far (Fraunhofer) zone of the radiated fields are obtained. Numerical computations are implemented to show the effects of the off-centered source feed asymmetrically covered by the hemi-spherical dielectric radome.

This paper presents an alternative analysis of obtaining radiated electromagnetic (EM) fields in a dielectric prolate spheroid using the perturbation technique. A circular loop antenna is used as a radiator on the top of the spheroid. The spheroid is approximated by the first a few terms of the Taylor series expansion (higher-order approximation), and coefficients for transmission and scattered EM fields are found using the perturbation method where the coefficients are also expanded into Taylor series and determined by matching the boundary conditions on the spheroidal dielectric surface. After the approximated coefficients and EM fields are obtained, validity of the approach is discussed and limitations are also addressed.

We discuss the problem of the reconstruction of the profile of an inhomogeneous object from scattered field data. Our starting point is the contrast source inversion method, where the unknown contrast sources and the unknown contrast are updated by an iterative minimization of a cost functional. We discuss the possibility of the presence of local minima of the nonlinear cost functional and under which conditions they can exist. Inspired by the successful implementation of the minimization of total variation and other edgepreserving algorithms in image restoration and inverse scattering, we have explored the use of these image-enhancement techniques as an extra regularization. The drawback of adding a regularization term to the cost functional is the presence of an artificial weighting parameter in the cost functional, which can only be determined through considerable numerical experimentation. Therefore, we first discuss the regularization as a multiplicative constraint and show that the weighting parameter is now completely prescribed by the error norm of the data equation and the object equation. Secondly, inspired by the edge-preserving algorithms, we introduce a new type of regularization, based on a weighted L2 total variation norm. The advantage is that the updating parameters in the contrast source inversion method can be determined explicitly, without the usual line minimization. In addition this new regularization shows excellent edge-preserving properties. Numerical experiments illustrate that the present multiplicative regularized inversion scheme is very robust, handling noisy as well as limited data very well, without the necessity of artificial regularization parameters.

In this paper, the characteristics of a small antenna using an H-shaped microstrip patch are studied. Significant reduction of antenna size can be realized when the H-shaped patch is used instead of the conventional rectangular microstrip patch antenna. The theoretical analysis is carried out based on the finite-difference timedomain (FDTD) method. The FDTD programs are developed and validated by available measurement results. The effects of various antenna parameters on the resonant frequency and radiation patterns are shown. Several design curves are presented, which are useful for practical antenna design. The electric current distributions on the patch and those on the ground plane are described, together with the results illustrating the electric field distributions under the patch. This antenna is suitable for applications where small size and broad beamwidth are required.

A fast and efficient method for analyzing an inset dielectric guide is presented using the Fourier transform technique with a modified perfectly matched boundary. In order to deal with an open region, a novel idea, modified perfectly matched boundary condition (PMB), has been proposed. By introducing the modified PMB, the numerical integral has been avoided and the accuracy of the numerical solution has been improved. Moreover, the singular behavior of the fields at metal edge is taken into account in the analysis. The numerical examples are shown that the convergence of the solution is very fast and the relative error less than 0.07% is attained even if only the first term is considered in the field expansion of the guide. The numerical results of the propagation constants for single- and double-layered inset dielectric guides agree well with those of literatures.

This paper presents a method of moments (MoM) analysis, obtains the non-uniform current distribution in closed form, and computes the resulted radiated patterns in both near and far zones, of square and rectangular loop antennas with electrically larger perimeter. An oblique incident field in its general form is considered in the formulation of the non-uniform current distributions. In the Galerkin's MoM analysis, the Fourier exponential series is considered as the fulldomain basis function series. As a result, the current distributions along the square and rectangular loops are expressed analytically in terms of the azimuth angle for various sizes of large loops. Finally, an alternative vector analysis of the electromagnetic (EM) fields radiated from thin rectangular loop antennas of arbitrary length 2a and width 2b is introduced. This method which employs the dyadic Green's function (DGF) in the derivation of the EM radiated fields makes the analysis general, compact and straightforward in both near- and farzones. The EM radiated fields are expressed in terms of the vector wave eigenfunctions. Not only the exact solution of the EM fields in the near and far zones outside √a2 + b2 are derived by the use of the spherical Bessel and Hankel functions of the first kind respectively, but also the inner regions between a and √a2 + b2 are characterized by both the spherical Bessel and Hankel functions of the first kind. Validity of the numerical results is discussed and clarified.

Rigorous Coupled Wave Analysis (RCWA) (used for electromagnetic (EM) analysis of planar diffraction gratings) has been applied to solve EM scattering and diffraction problems for spatially inhomogeneous, cylindrical, elliptical systems. The RCWA algorithm and an appropriate method for matching EM boundary conditions in the elliptical system are described herein. Comparisons of the eigenfunctions determined by RCWA (found in spatially homogeneous elliptical regions) and Mathieu functions are presented and shown to agree closely with one another. Numerical results of scattering from a uniform elliptical shell system (excited by an electrical surface current) obtained by using both a Mathieu function expansion method and by using the RCWA algorithm are presented and also shown to agree closely with one another. The RCWA algorithm was used to study EM scattering and diffraction from an elliptical, azimuthally inhomogeneous dielectric permittivity, step profile system. EM field matching and power conservation were shown to hold for this step profile example. A comparison of the EM fields of the step profile elliptical shell example and that of a uniform profile elliptical shell having the same excitation and bulk material parameters (permittivity and permeability) was made and significant differences of the EM fields of the two systems were observed.

We present a method giving the field scattered by a plane surface with a cylindrical local perturbation illuminated by a plane wave. The theory is based on Maxwell's equations in covariant form written in a nonorthogonal coordinate system fitted to the surface profile. The covariant components of electric and magnetic vectors are solutions of a differential eigenvalue system. A Method of Moments (PPMoM) with Pulses for basis and weighting functions is applied for solving this system in the spectral domain. The scattered field is expanded as a linear combination of eigensolutions satisfying the outgoing wave condition. Their amplitudes are found by solving the boundary conditions. Above a given deformation, the Rayleigh integral is valid and becomes identified with one of covariant components of the scattered field. Applying the PPMo Method to this equality, we obtain the asymptotic field and the scattering pattern. The method is numerically investigated in the far-field zone, by means of convergence tests on the spectral amplitudes and on the power balance criterion. The theory is verified by comparison with results obtained by a rigorous method.

The diffraction of E-polarized plane waves by a tandem impedance slit waveguide is investigated rigorously by using the Fourier transform technique in conjunction with the Mode Matching method. This mixed method of formulation gives rise to a scalar Wiener-Hopf equation of the second kind,the solution of which contains infinitely many constants satisfying an infinite system of linear algebraic equations. A numerical solution of this system is obtained for various values of the surface impedances,slit width and the distance between the slits,through which the effect of these parameters on the diffraction phenomenon are studied.

The field scattered by a perfectly conducting plane surface with a perturbation illuminated by an E//-polarized plane wave is determined by means of a Rayleigh method. This cylindrical surface is described by a local function. The scattered field is supposed to be represented everywhere in space by a superposition of a continuous spectrum of outgoing plane waves. A "triangle/Dirac" method of moments applied to the Dirichlet boundary condition in the spectral domain allows the wave amplitudes to be obtained. For a half cosine arch,the proposed Rayleigh method is numerically investigated in the far-field zone,b y means of convergence tests on the spectral amplitudes and on the power balance criterion. We show that the Rayleigh integral can be used for perturbations,the amplitudes of which are close to half the wavelength.

Accurate determination of the generalized scattering matrix of the crossed waveguides junction, T-junction and right-angle bend containing a cylindrical post is presented. The generalized scattering matrix of the four port structure is obtained from those of the two ports right angle bend with different combinations of perfect electric and/or magnetic walls. The generalized scattering matrix of the right angle bend (quarter of the structure) is obtained by the mode matching method where the electromagnetic fields in rectangular waveguides are matched to those in a junction section formed by asectoral region.

Luebbers' and Maliuzhinets' solutions for diffraction by alossy wedge are compared in order to model the urban propagationchannel. Derivation, validity criteria and accuracy of impedanceboundary conditions (IBCs) --- as a main approximation embedded inthe Maliuzhinets' solution—are discussed. A modified (a slightlyimproved) Luebbers diffraction coefficient is proposed. The UniformTheory of Diffraction (UTD) Maliuzhinets diffraction coefficient isgiven in a structured form that might facilitate its use. Detailednumerical comparisons of the above-mentioned solutions with method-of-moments solutions using either exact boundary conditions or IBCsare done for canonical configurations.

Constitutive relations for isotropic material media are formulated in a manifestly covariant manner. Clifford's geometric algebra is used throughout. Polarisable,c hiral and Tellegen medium are investigated. The investigation leads to the discovery of an underlying algebraic structure that completely classifies isotropic media. Variational properties are reviewed,sp ecial attention is paid to the imposed constraints on material parameters. Covariant reciprocity condition is given. Finally,dualit y transformations and their relevance to constitutive relations are investigated. Duality is shown to characterise ‘well-behavedness' of medium which has an interesting metric tensor related implication.

This paper concerns the implementation of the perfectly matched layer (PML) absorbing boundary condition in the framework of a mimetic differencing scheme for Maxwell's Equations. We use mimetic versions of the discrete curl operator on irregular logically rectangular grids to implement anisotropic tensor formulation of the PML. The form of the tensor we use is fixed with respect to the grid and is known to be perfectly matched in the continuous limit for orthogonal coordinate systems in which the metric is constant, i.e. Cartesian coordinates, and quasi-perfectly matched (quasi-PML) for curvilinear coordinates. Examples illustrating the effectiveness and long-term stability of the methods are presented. These examples demonstrate that the grid-based coordinate implementation of the PML is effective on Cartesian grids, but generates systematic reflections on grids which are orthogonal but non-Cartesian (quasi-PML). On non-orthogonal grids progressively worse performance of the PML is demonstrated. The paper begins with a summary derivation of the anisotropic formulation of the perfectly matched layer and mimetic differencing schemes for irregular logically rectangular grids.

The focus of this paper is on the solution of Maxwell's equations for time-harmonic fields on triangular, possibly nonorthogonal meshes. The method is based on the well-known Finite Integration Technique (FIT) [33, 35] which is a proven consistent discretization method for the computation of electromagnetic fields. FIT on triangular grids was first introduced in [29, 31] for eigenvalue problems arising in the design of accelerator components and dielectric loaded waveguides. For many technical applications the 2D simulation on a triangular grid combines the advantages of FIT, as e.g. the consistency of the method or the numerical advantage of banded system matrices, with the geometrical flexibility of non-coordinate grids. The FIT-discretization on non-orthogonal 2D grids has close relations [26] to the N´ed´elec elements [14, 15] or edge elements in the Finite Element Method.

A desire to unify the mathematical description of many physical theories, such as electrodynamics, mechanics, thermal conduction, has led us to understand that global (=integral) physical variables of eachth eory can be associated to spatial geometrical elements suchas points, lines, surfaces, volumes and temporal geometrical elements suchas instants and intervals. This association has led us to build a space-time classification diagram of variables and equations for each theory. Moreover, the possibility to express physical laws directly in a finite rather than differential form has led to the development of a computational methodology called Cell Method [12]. This paper discusses some practical aspects of this method and how it may overcome some of the main limitations of FDTD method in electrodynamics. Moreover, we will provide some numerical examples to compare the two methodologies.

We report some properties of the Finite Integration Technique (FIT), which are related to the definition of a discrete energy quantity. Starting with the well-known identities for the operator matrices of the FIT, not only the conservation of discrete energy in time and frequency domain simulations is derived, but also some important orthogonality properties for eigenmodes in cavities and waveguides. Algebraic proofs are presented, which follow the vectoranalytical proofs of the related theorems of the classical (continuous) theory. Thus, the discretization approach of the FIT can be considered as the framework for a consistent discrete electromagnetic field theory.

The calculus of differential forms can be used to devise a unified description of discrete differential forms of any order and polynomial degree on simplicial meshes in any spatial dimension. A general formula for suitable degrees of freedom is also available. Fundamental properties of nodal interpolation can be established easily. It turns out that higher order spaces, including variants with locally varying polynomial order, emerge from the usual Whitneyforms by local augmentation. This paves the way for an adaptive pversion approach to discrete differential forms.