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Electromagnetic Devices (electromagnetic + device)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Krylov model order reduction of finite element approximations of electromagnetic devices with frequency-dependent material properties

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2007
Hong Wu
Abstract A methodology is presented for the Krylov subspace-based model order reduction of finite element models of electromagnetic structures with material properties and impedance boundary conditions exhibiting arbitrary frequency dependence. The proposed methodology is a generalization of an equation-preserving Krylov model order reduction scheme for methodology for second-order, linear dynamical systems. The emphasis of this paper is on the application of this method to the broadband model order reduction of planar circuits including lossy strips of arbitrary thickness and lossy reference planes. In particular, it is shown that the proposed model order reduction methodology provides for the accurately modelling of the impact of the frequency dependence of the internal impedance per unit length of the thick lossy strip on the electromagnetic response of the stripline structure over a very broad, multi-GHz frequency band, extending all the way down to frequencies in the DC neighbourhood. In addition, the application of the proposed methodology to the broadband modelling of electromagnetic coupling between strips on either side of a lossy ground plane is demonstrated. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A full-wave space-domain method for the analysis of leaky-wave modes in multilayered planar open parallel-plate waveguides

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2005
José Luis Gómez-Tornero
Abstract This work presents a novel numerical technique for the analysis of leaky-wave modes in laterally shielded, top-open multilayered planar transmission lines. The method develops the multilayered-media boxed Green's functions for this type of electromagnetic devices, and solves the characteristic electric-field integral equation (EFIE) by using the method of moments (MoM). The analytical expressions used for the computation of the kernel of this technique are derived in this article, and results for leaky-wave modes in different practical structures are presented. The strong analytical nature of the proposed approach allows for a low-cost computational code without losing its full-wave accuracy. Comparisons with previous works are presented, showing the advantages of this new method for the analysis and design of practical millimeter-band leaky-wave antennas. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Multiferroic Properties of Nanocrystalline PbTiO3 Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010
Min Wang
Nanocrystalline PbTiO3 (PTO) powders in a perovskite structure have been synthesized by the sol,gel process using lead acetate, glycerin, and titanium (IV) isopropoxide as precursors. PTO ceramics were obtained by sintering the powders at temperatures ranging from 600° to 1000°C. The structure and morphology of the ceramics have been determined by X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy. The PTO powder calcined at 450°C shows weak ferromagnetism at room temperature. The PTO ceramics sintered at various temperatures exhibit coexistence of ferroelectricity and weak ferromagnetism at room temperature. Enhancement in the magnetic moment and ferroelectricity with a reduction in the grain size of PTO ceramics was observed. This result facilitates the possibilities of new perovskite electromagnetic devices at the nanoscale level. [source]

Application of algebraic domain decomposition combined with Krylov subspace iterative methods to solve 3D vector finite element equations

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
X. W. Ping
Abstract In this paper, a parallel algorithm based on MPI (Message Passing Interface) parallel computing library for the finite element method is presented to analyze three-dimensional electromagnetic devices. The algebraic domain decomposition method is used in the algorithm. The original problem is decomposed into several subproblems according to its features. Each of them is allocated to one process in one computation node and solved independently with a direct method. The data are exchanged by communication between adjacent subdomains with overlapped data based on the MPI network. The example of its application is given. Numerical shows that the proposed algorithm can get excellent performance vs. price ratio and can save much memory and CPU time than sequential computing. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 686,692, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22247 [source]