摘要:

An exact relativistic solution to the problem of electromagnetic wave scattering by uniformly translating bodies can be performed by applying Lorentz field transforming formulae to plane wave spectra representing impinging and scattered fields. An application to the two-dimensional problem of a monochromatic plane wave scattering for the case of one cylinder in the presence of a plane interface has been carried out. By virtue of a peculiar notation for electromagnetic vector fields used throughout the paper, the application of Lorentz formulae to plane waves and to plane-wave expandable fields can be easily expressed by altering propagation parameters (amplitude, frequency and direction).

ISSN:0920-5071    

DOI:10.1163/156939300X00969

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this work, Characteristic Modes in conjunction with Spectral Domain Moment Method are used for the efficient analysis of the scattering from arrays of arbitrarily shaped microstrip patches. In the following the Theory of Characteristic Modes for a general arrays of patches is presented. The method is tested by considering simple structure composed by two patches only but it can be extended to larger arrays. Computed results are found to be in excellent agreement with results obtained by standard MoM with subdomain basis functions. Since a small number of characteristic modes are necessary to yield a good approximation of the induced current on patches, the proposed method dramatically reduce the number of unknowns and the corresponding computational effort in the MoM solution of the problem. For this reason it allows the analysis of larger arrays with direct inversion methods.

ISSN:0920-5071    

DOI:10.1163/156939300X00978

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The analysis of a lossless helical slow-wave structure (SWS) using equivalent circuit approach, reported elsewhere, had been carried out for the fundamental mode only. This is essentially used to predict the transmission line parameters. Moreover, in the analysis the effect of permittivity on the radial propagation constant has not been considered. The radial propagation constant was considered to be same over the different structure regions. In this paper, the analysis has been developed for the space-harmonic modes considering different radial propagation constant over different structure regions. Due to it, the present analysis becomes more general, accurate and capable of dealing with a wide range of structure parameters. The dispersion relation developed here in terms of the equivalent line parameters for a lossless structure, namely, shunt capacitance per unit length and series inductance per unit length for the space-harmonic modes, as a special case, passes on to those obtained earlier by considering same radial propagation constants over different structure regions and for the fundamental mode. Besides the dispersion characteristics, characteristics impedance has also been predicted in terms of line parameters. The results presented here in terms of the structure parameters can be used

ISSN:0920-5071    

DOI:10.1163/156939300X00987

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In the present work the resonance properties of TM01and TM11modes of a spherical-circular patch antenna are investigated when loaded with single shorting post. The cavity model is used to predict the frequencies of the resonant modes. It is shown that angle of curvature has a significant effect on the tunability of the resonant modes. Beyond a critical angle of curvature the resonant frequency of the post loaded disk on sphere decreases with increasing radial distance of post from the centre of the patch. This is in complete reversal to the trend displayed by a planar circular disk antenna loaded with shorting post. Also demonstrated is the fact that asymmetric post loading leads to generation of three split resonances. Preliminary experiments conducted on such shorted patch antennas, corroborates the theory.

ISSN:0920-5071    

DOI:10.1163/156939300X00996

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We describe how antenna sum patterns can be controlled by modifying just the phase distribution of the excitation. As examples, we calculate linear and circular aperture distributions affording symmetric sum patterns with low side lobe levels, and linear aperture distributions affording patterns with low sidelobe levels on one side of the beam.

ISSN:0920-5071    

DOI:10.1163/156939300X01003

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper presents an efficient integral transform technique for evaluating the singular part of the scalar and vector potentials due to a uniform current subdipole. By performing several transformations, the original double integral 1/-Rswith a singular kernal can be represented as a finite one-dimensional integral whose integrand possesses an analytically integrable logarithmic singularity. The results of the newly driven integral are compared with those using other available numerical methods and checked the validity of the proposed method.

ISSN:0920-5071    

DOI:10.1163/156939300X01012

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Modeling of long range propagation of collimated wavepackets poses some major difficulties with the conventional FDTD scheme. The difficulties arise from the vast computer resources needed to discretize the entire region of interest and the accumulation of numerical dispersion error. As a means for circumventing these difficulties, the moving frame FDTD approach is in this work. In this approach, the computational grid size is limited to the order of the pulse length, and it and moves along with the pulse. The issues discussed in conjunction with this method are those of numerical dispersion, which is shown to be reduced substantially compared with the stationary formulation, numerical stability, and absorbing boundary conditions at the leading, trailing and side boundaries, Numerical results of pulsed beam propagation in both homogeneous and plane stratified media are shown, and the capability of the method is demonstrated with propagation distances exceeding the order of 104pulse lengths.

ISSN:0920-5071    

DOI:10.1163/156939300X01021

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper studies the electromagnetic field radiated by an infinitely long thin wire-antenna which uniformly translates in a direction parallel to a plane interface. An exact relativistic solution is performed through the application of Lorentz field transformation formulae to the plane wave spectrum representing the radiated field in the rest frame of the antenna. The occurrence of peculiar relativistic phenomena is highlighted by means of numerical examples.

ISSN:0920-5071    

DOI:10.1163/156939300X01030

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The adaptive integral method (AIM) is applied in this paper to calculate the capacitance coefficients for an arbitrarily shaped three-dimensional structure. The uniformity of multipole moment approximation is revealed theoretically and numerically; it is realized that the approach can guarantee the accuracy of AIM for computing capacitance of any structure. The memory requirement and computational complexity of the present method are less than O(N1.5) and O(N1.5log N) for three-dimensional problems, respectively. Numerical experiments for several conducting structures demonstrate that the present method is accurate and efficient to compute capacitance of an arbitrarily shaped three-dimensional structure.

ISSN:0920-5071    

DOI:10.1163/156939300X01049

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Unique effects of the double helical conductances of the surfaces (HCS) on the Mueller matrix (Mm) of a two-layer eccentrically bianisotropic cylinder linear array are investigated in this paper. The mathematical treatment is conducted based on the boundary-value approach combined with the technique of generalized separation variables. Both the TMz- and TEz-polarization of the obliquely incident waves are taken into account in the analysis. To gain insight into some physical mechanisms, numerical examples are presented to show the influences of the variations of the twist angles on the behavior of Mm of a linear array of four bianisotropic cylinders. Correspondingly, various magnetic symmetry groups (such as D∞(C∞), C∞v(C∞), D∞h(D∞), C∞h(C∞)) and some generalized symmetry and anti-symmetry relations, which govern all the elements of Mm or the scattering cross section under special chiral operations, are demonstrated. The present studies can be exploited to identify the constitutive characteristics of some bianisotropic media and to provide better understanding of the electromagnetic wave interaction with bianisotropic cylindrical objects with complex boundaries.

ISSN:0920-5071    

DOI:10.1163/156939300X01058

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor