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Practical Structures (practical + structure)
Selected AbstractsAnalysis and characterization of package resonanceINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2005El-Badawy El-Sharawy Abstract This article presents FDTD analysis and prediction of the overall effects of the resonance in ceramic and plastic packages. Practical structures that result in strong resonance effects are investigated, such as coupled cross lines with a via transition and multiple via transitions on a single line. A detailed study of the mutual coupling, including resonance effects, is also performed and presented. The results of the analysis indicate that the package performance can be very sensitive to the resonance effects. A broadband equivalent-circuit model for multiple transition discontinuities (two via holes) on a single line has been developed and presented. Good agreement between the frequency response of the FDTD and the circuit models has been achieved over a broad band of frequencies. The analysis presented in this article provides insight about the limits at which coupling effects on the overall package performance can be neglected. The equivalent-circuit model presented in this article can greatly simplify the analysis and simulation of a complex package, including several transition discontinuities, assuming that the coupling is small. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source] An internal multiband antenna for WLAN and WWAN applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2009Chien-Wen Chiu Abstract In this letter, we propose a novel multiband antenna which can be integrated into a laptop computer for WLAN and WWAN applications. The antenna, evolved from a dual-band inverted-F antenna, is mounted on the top-edge of a vertical ground plane of LCD panel. By adding four parasitic resonators which are short-circuited quarter-wavelength elements, the antenna can achieve wideband performance to cover GSM850/GSM900/DCS/PCS/UMTS and 802.11a/b/g. A simulation was performed by HFSS to optimally design the antenna, and then a practical structure was also fabricated to verify the simulation results. The measured antenna parameters as well as the radiation efficiency are presented to validate the proposed antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1803,1807, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24501 [source] Spatial Patterning of the , -Phase in Poly(9,9-dioctylfluorene): A Metamaterials-Inspired Molecular Conformation Approach to the Fabrication of Polymer Semiconductor Optical StructuresADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Gihan Ryu Abstract Materials in which sub-wavelength physical structures, rather than variations in chemical composition, are used to modify the nature of their interaction with electromagnetic radiation form the promising new class of metamaterials. For molecular materials one has an intriguing alternative, namely structuring the conformation or physical geometry of the molecule. In order for this to be an effective methodology one needs the change in conformation i) to engender a significant change in electromagnetic properties and ii) to be spatially controllable to allow patterning of practical structures. In this paper the potential of such an approach is demonstrated through spatial patterning, via masked solvent vapor exposure, of the , -phase conformation in poly(9,9-dioctylfluorene) (PFO). Significantly the conformation change approach preserves a planar film format and is found not to negatively impact on optical gain properties, both very attractive features for optoelectronic and photonic lightwave circuit applications. As a specific demonstration the ability to spatially control the lasing wavelength for samples in which a , -phase conformation is selectively patterned in a glassy PFO film spin coated atop a one-dimensional distributed-feedback grating etched into a spectrosil substrate is shown. [source] Thermal flutter analysis of large-scale space structures based on finite element methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007Wei Li Abstract During the orbital day,night crossing period, the suddenly applied thermal loading is apt to introducing vibration on flexible appendages of large-scale space structures. This kind of thermally-induced vibration is a typical failure of modern spacecrafts. However, owing to the complexity of this problem, many earlier researches study only the vibration of simplified beam models, which can hardly describe the performance of practical structures. This paper aims at using the finite element method to analyse the non-linear vibration of practical thin-walled large-scale space structures subjected to suddenly applied thermal loading. In this study, the coupling effect between structural deformations and the incident normal solar heat flux is considered; the necessary condition of thermally-induced vibration is verified; and the criterion of thermal flutter is established. Copyright © 2006 John Wiley & Sons, Ltd. [source] A full-wave space-domain method for the analysis of leaky-wave modes in multilayered planar open parallel-plate waveguidesINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2005José 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] Applications of transformed-space non-uniform PSTD (TSNU-PSTD) in scattering analysis without the use of the non-uniform FFTMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2003Xiaoping Liu Abstract In this work, we extend the transformed-space, non-uniform pseudo-spectral time domain (TSNU-PSTD) Maxwell solver for a 2D scattering analysis. Prior to implementing the PSTD in this analysis, we first transform the non-uniform grids {xi} and {yj} sampled in the real space for describing complex geometries to uniform ones {ui} and {vj}, in order to fit the dimensions of practical structures and utilize the standard fast Fourier transform (FFT). Next, we use a uniform-sampled, standard FFT to represent spatial derivatives in the space domain of (u, v). It is found that this scheme is as efficient as the conventional uniform PSTD with the computational complexity of O(N log N), since the difference is only the factors of du/dx and dv/dy between the conventional PSTD and the TSNU-PSTD technique. Additionally, we apply an anisotropic version of the Berenger's perfectly matched layers (APML) to suppress the wraparound effect at the open boundaries of the computational domain, which is caused by the periodicity of the FFT. We also employ the pure scattered-field formulation and develop a near-to-far-zone field transformation in order to calculate scattered far fields. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 16,21, 2003 [source] | ||||||||||