摘要:

The analysis of electromagnetic scattering from a large, deep, and arbitrarily-shaped open cavity is a very difficult task because of a large number of unknowns resulting from the discretization of the cavity. In this paper, we present a very efficient technique to deal with this problem. This technique is based on the finite-element method that is known for its capability to handle arbitrary geometries and complex material composition. The technique exploits the unique features of the finite-element equations and, more importantly, the unique features of the problem of scattering by a large and deep cavity. It is designed in such a manner that it uses a minimal memory, which is proportional to the aperture size of the cavity and independent of the depth of the cavity, and its computation time increases only linearly with the depth of the cavity. Furthermore, it computes the scattered fields for all angles of incidence without requiring significant additional time. The technique is applied to both two and three dimensional cavities whose interior may be coated with radar absorbing materials. Excellent results are obtained for two dimensional cavities and those for three dimensional cavities are also promising.

ISSN:0272-6343    

DOI:10.1080/02726349808908568

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Electromagnetic phenomena can be simulated by the dynamics of a mechanical system as long as the Hamiltonian of the electromagnetic and the mechanical systems coincide. In this paper we present a generalization of G.F. FitzGerald's pulleys and rubber-bands mechanical model for the interaction of electromagnetic waves with complex media. We show a direct analogy between the FitzGerald model and the electric vector potential formulation, at each stage of the extension of the original model: each mechanical observable has a unique correspondence in the vector potential formulation. This strict analogy allows further inductive developments of the mechanical model and extends the pedagogical importance of the original FitzGerald model. As a consequence very complex materials from the electromagnetic point of view, such as frequency dependent magneto dielectric materials are easily understood and implemented with simple modifications in the mechanical system. The condense node representation of the field in the vector potential formulation results in lower grid dispersion compared to other numerical techniques such as the Finite Difference Time Domain (FDTD), We describe several applications, such as classical scattering problems from dielectric, magnetically permeable, dielectritcally lossy and Debye materials. The simulations are validated with comparison to canonical solutions, or with FDTD calculations.

ISSN:0272-6343    

DOI:10.1080/02726349808908569

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A current-expansion technique is proposed to analyze the waveguide discontinuities of irregular shape. Roof-top and rectangular-pipe sub-domain functions are used in an electric-field integral-equation formulation to adequately expand the three-dimensional current densities of an irregularly-shaped conductor. It is therefore applicable to quite general discontinuity configurations. Numerical results for a variety of waveguide discontinuities including open-ends, bends, and T junctions have been demonstrated and verified by the available published data.

ISSN:0272-6343    

DOI:10.1080/02726349808908570

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A Finite Element Method (FEM) is presented to determine reflection and transmission coefficients of rectangular waveguide junction discontinuities. H-, E- plane discontinuities in a concentric/non concentric rectangular waveguide junction are analyzed using the FEM procedure. Also, reflection and transmission coefficients due to presence of a gap between two sections of a rectangular waveguide are determined using the FEM. The numerical results obtained using the FEM procedure are compared with results obtained using the Mode Matching Method (MMM) and with measured data.

ISSN:0272-6343    

DOI:10.1080/02726349808908571

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor