摘要:

A method for handling the non-homogeneous terms occurring in the method of moments formulation of the Poisson equation is proposed. The algorithm is based on using the Fourier series expansions for solving the general two-dimensional Poisson equation without the need for either domain discretization nor Monte Cario integration techniques. The convergence of the present method is studied and improved by using the algorithm. Application of this method to the determination of the depletion layer profile is presented along with several other engineering problems. The results are compared with solutions available in the literature.

ISSN:0920-5071    

DOI:10.1163/156939397X00332

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An optimization approach is used in the design of weakly reflecting plane-stratified slabs where transient plane waves impinges obliquely. The slabs are dispersive with a spatially varying impedance and conductivity. In the optimization process, the direct problem is solved iteratively by a time-domain Green functions technique which deals with scattering kernels. Given the prescribed reflection and transmission kernels, an objective functional is minimized for a time larger than one roundtrip and for given incident directions. By introducing dual functions, the exact and explicit expressions for the gradients are derived for the TE and TM modes.

ISSN:0920-5071    

DOI:10.1163/156939397X00341

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An investigation of the spatial decomposition technique (SDT) for the analysis of electrically large objects is presented. We apply SDT to two-dimensional perfectly conducting cylinders under TM excitation. Some of the convergence issues of the SDT as well as its application to finite arrays (finite frequency selective surfaces) are discussed. We also present a new method to obtain a reduction in the operation count of SDT, which is referred to as "reduced current fidelity (RCF)." With RCF the coupling between distant SDT subobjects is determined by use of a coarse grid on which currents are obtained from those on a dense grid. An averaging of the currents on distant objects reduces the operation count involved in determining the coupling to other subobjects. It is shown that for electrically large structures, RCF can provide significant reduction in operation count and good accuracy in the resulting structure currents.

ISSN:0920-5071    

DOI:10.1163/156939397X00350

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A mathematical formalism describing plane electromagnetic wave scattering by a linear chain of N triaxial dielectric ellipsoids of complex index of refraction is presented. The Fredholm integral equation theory is employed. As a first approximation, electromagnetic coupling between only neighbouring scatterers is taken into account. The case of non-negligible coupling between any pairs of scatterers is a straightforward extension of the present treatment. However, the computing time demands in that case are particularly high. The analysis is based on the Lippman-Schwinger integral equation for the electric field. The corresponding integral equation for the scattering, which contains N singular kernels, is transformed into N non-singular integral equations for the angular Fourier transform of the field indide each scatterer. The latter equations are solved by reducing them by quadrature into a matrix equation. The resulting solutions are used to calculate the scattering amplitude. As a numerical application, the case of a red blood cell rouleau consisting of three adjacent oblate spheroidal models of erythrocytes is considered. Typical values of the appropriate discretization parameters which are sufficient for achieving convergence, as well as certain validity tests are provided. The effect of electromagnetic coupling between neighbouring scatterers is demonstrated. Efficient techniques for reducing the rather high computing requirements of the analysis, such as parallel processing, are both suggested and applied.

ISSN:0920-5071    

DOI:10.1163/156939397X00369

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We consider the problem of the electromagnetic modes which exist in a doubly periodic structure consisting of a square or hexagonal array of cylinders, and focus on a special type of mode called the TEM mode. We discuss the link between the TEM mode, the off-axis mode which tends towards it for small wave numbers and near-normal incidence, and the effective refractive index of the array. For arrays of finitely conducting cylinders we show that the quasistatic limits of TE and TM modes are different. When the structure contains perfectly conducting cylinders, we show that there is no such limit for TM modes, as the corresponding photonic band diagram does not contain an acoustic band. Our results highlight the restrictions regarding the validity of homogenization procedures for doubly periodic composites.

ISSN:0920-5071    

DOI:10.1163/156939397X00378

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The electrostatic problem of a conducting circular disk resting over a grounded dielectric slab is formulated in terms of dual integral equations. Following Sneddon [9] the dual integral equations are replaced by a more manageable inhomogeneous Fredholm integral equation of the second kind in which the unknown represents the charge density. The solution of the latter equation is expressed in terms of Neumann series whose integral yields the capacitance. For values of slab thickness small compared to the radius of the disk convergence of the series is very slow and numerical evaluation became so tedious that one could not proceed beyond the sixth term. However, by applying Shank and Aitken acceleration methods to the partial sums very accurate results have been realized. Yet another powerful method of solution is based on calculus of variations. A lower bound for the capacitance in terms of charge density has been obtained. Trial function for the charge density consists of two terms, a constant plus one with an appropriate singularity at the edge. These are weighted in such manner that the constant and singular term dominate, respectively, for small and large slab thicknesses which is in keeping with what rnight one expect in reality. Plots of capacitance versus thickness of the grounded slab with dielectric constant as a parameter are provided.

ISSN:0920-5071    

DOI:10.1163/156939397X00387

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939397X00396

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor