摘要:

This paper presents an alternative approach to develop the cylindrical vector wave function representations of electromagnetic fields in source-free gyrotropic bianisotropic media. The formulation is carried out directly in angular spectral domain in cylindrical coordinate system thus obviating cumbersome rectangular-cylindrical coordinate transformation and mathematical manipulations in conventional Cartesian Fourier domain method. As the media under study belong to the most general coaxially gyrotropic type, the field expansion coefficients obtained here recover all previously considered cases of composite materials. A set of vector functions defined transverse and longitudinal to gyrotropic axis is introduced and exploited to facilitate analysis and be related to the commonly employed vector wave functions. Application of the present field representations in electromagnetic scattering by an infinitely long gyrotropic bianisotropic cylinder is discussed.

ISSN:0920-5071    

DOI:10.1163/156939399X00501

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The classical TE/TM decomposition theory, valid for isotropic and uniaxially anisotropic media, has recently been generalized to a class of bi-anisotropic media. In such a decomposable medium any electromagnetic field can be decomposed into two individual electromagnetic fields, an a-field and a b-field, satisfying certain polarization conditions. The natural continuation of the theory is to decompose the electromagnetic sources that is the topic of the present paper. The differential equations for the a- and b-sources are derived and seen to generalize the previous results. Also one example of possible source decomposition is suggested.

ISSN:0920-5071    

DOI:10.1163/156939399X00510

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A method for the array pattern synthesis in the presence of near-zone scatterers in the three-dimensional vector case is presented. The synthesis is based on the minimization of an objective function using the simulated annealing technique. In order to take into account the effects of the scatterers, the physical optics approximation is used. The polarization in both the incident and the scattered fields is also taken into account. Examples for a 10 x 10-element planar array of dipoles in the presence of a perfectly electric conducting cylinder are presented.

ISSN:0920-5071    

DOI:10.1163/156939399X00529

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We present a new matrix differential equation formulation for the analysis of the response of linearly and non linearly loaded molecules to an incoming electromagnetic wave. The molecule is defined as an electrically small dipole or loop antenna connected to an electronic circuit called the load. Because we have a Maxwell FDTD code, we use a finite difference scheme to solve the differential equations, which greatly simplifies the problem. If the load is linear, a simple linear system of update equations can easily be derived from the system of differential equations describing the behavior of the load circuit. This approach leads to a natural choice for the intermediate unknowns in the use of the Auxiliary Differential Equation method, and gives a fully explicit matricial update equation. If the load contains one or more non linear devices, this method can be generalized and leads to the resolution of a system of non linear update equations with a simple Newton Raphson or Runge Kutta algorithm. Several numerical examples are shown, for dielectric molecules.

ISSN:0920-5071    

DOI:10.1163/156939399X00538

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A genetic algorithm (GA) is used to obtain pattern nulling and main beam scanning of the array feed parabolic reflector. Unlike conventional GA using a random initial population, in this study, one of the initial individuals is designated as conjugate field matching (CFM) weight vector. The implemented GA algorithm is tested for both phase-amplitude array and phase-only array feed for parabolic reflectors. Various results are presented to show the performance of the algorithm.

ISSN:0920-5071    

DOI:10.1163/156939399X00547

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Starting from the effective parameters of the chiral mixture and the polarizabilities of the inclusions, influences of the coherent scattering effects of the inclusions on the attenuation of electromagnetic waves in the mixture are explicitly presented, by introducing the pair-distribution function of the inclusions.

ISSN:0920-5071    

DOI:10.1163/156939399X00556

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

When solving electromagnetic problems, integral equation methods, such as the Method of Moments, are known to yield to dense matrix systems whose solution usually supposes an intensive computational cost. Continuous efforts have been developed to overcome this drawback. In this paper, the goal is to generate a set of basis functions defined over the entire domain and characterized by a null radiated power coupling in the far-field region. This behavior permits to diminish the density of unknowns per wavelength, considering only a reduced set of the new basis. Furthermore, the resulting matrix has a sparse structure. All these factors amounts to considerable savings in terms of computer storage and CPU requirements.

ISSN:0920-5071    

DOI:10.1163/156939399X00565

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper presents a new uniplanar microwave mixer circuit. The mixer utilizes even and odd modes on a coplanar waveguide to create a singly balanced mixer. The RF signal is fed quasi-optically as an even mode on a coplanar waveguide through a slot antenna while the local oscillator signal is fed to the same coplanar waveguide as an odd mode through an even-mode to odd-mode converter. The resulting mixer circuit is simple, compact, efficient, and can be scaled easily to millimeter wave frequencies.

ISSN:0920-5071    

DOI:10.1163/156939399X00574

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Numerical simulation of propagation of the electromagnetic waves in non-linear optical waveguides of planar and round constructions is discussed. Non-linear dielectric structure is described as multilayer system with the dielectric permeability supposed to be constant in each layer. Simple formulas for calculations of physical characteristics of non-linear optical structures of these types are obtained.

ISSN:0920-5071    

DOI:10.1163/156939399X00583

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A domain decomposition method (DDM) is presented for the solution of electromagnetic scattering problems by inhomogeneous 3-D bodies. The computational domain is partitioned into concentric subdomains on the interfaces of which Robin-type transmission conditions are prescribed. On the outer boundary terminating the computational domain, the radiation condition is taken into account by prescribing either an integral equation (IE) or an absorbing boundary condition. In the former case, the DDM decouples the inner problems, that correspond to the solution of Maxwell's equations inside each subdomain, from the outer problem solved by employing the IE. The convergence of the DDM algorithm to the solutions of the original problems is demonstrated when the dielectric permittivity and magnetic permeability tensors characterizing the inhomogeneous medium are those of passive materials.

ISSN:0920-5071    

DOI:10.1163/156939399X00592

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor