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9th International Conference on Ground Penetrating Radar (GPR 2002)

作者： Ellefsen, KJ Wright, DL US Geol Survey Denver CO 80225 USA

ISBN: (纸本)0819445223

To understand better how a borehole antenna radiates radar waves into a fori-nation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.

关键词： finite-difference time-domain method borehole radar antenna radiation pattern

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Unit cell approach to full-wave analysis of meander delay line using FDTD periodic structure Modeling method

Unit cell approach to full-wave analysis of meander delay li...

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10th Topical Meeting on Electrical Performance of Electronic Packaging

作者： Lee, H Kim, J Korea Adv Inst Sci & Technol Dept Elect Engn & Comp Sci Terahertz Media & Syst Lab Taejon 305701 South Korea

Unit cell modeling is performed to determine the effect of electromagnetic coupling on the propagation characteristics of a meander delay line, which is widely used in printed circuit boards and packages. Since the design of a delay line must guarantee a several tens of picosecond timing margin in modern highspeed packages and board level interconnections, a penetrating understanding of the meander effect is essential. The propagation delay, the characteristic impedance, and the stop-band characteristic of the meander delay line have been carefully investigated based on a full-wave analysis using the finite-difference time-domain (FDTD) periodic structure modeling method. The periodicity of the meander line is utilized based on Floquet's theorem, resulting in a reduction of the computational domain in the FDTD simulation and providing a unit cell model of the meander line. The unit cell modeling of the meander delay line shows the effect of electromagnetic coupling in meander line structure on the reduction of the propagation delay. Also, an analysis based on the unit cell modeling was confirmed by time-domain reflection/transmission measurements. To investigate the effects of variation of substrate thickness (H) and trace width (W) generated during the manufacturing process, the propagation delay and the characteristic impedance were analyzed with different values of H and W. The unit cell modeling approach based on Floquet's propagation mode analysis produces a transmission line model of the meander delay line, which gives the dispersion relation and the characteristic impedance. This work should prove useful for high-speed digital circuit board designers.

关键词： delay line finite-difference time-domain method meander periodic structure signal integrity

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Light propagation through alignment-patterned liquid crystal gratings

Light propagation through alignment-patterned liquid crystal...

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9th International Topical Meeting on Optics of Liquid Crystals

作者： Scharf, T Bohley, C Univ Neuchatel Inst Microtechnol CH-2000 Neuchatel Switzerland

We analysed the light propagation through alignment-patterned liquid crystal films where the alignment is planar and homeotropic for different domains, respectively. Using elastic theory the nematic director field can be analytically calculated with the method of conformal mapping in the one elastic constant approximation. A smooth change of the nematic director field is found with defect points at the substrate surfaces. In order to investigate the propagation of light passing through such a liquid crystalline thin film with spatially varying birefringence, we use a rigorous method. The use of rigorous methods allows the simulation of the time-dependent electric and magnetic fields for a region that is two-dimensional and possibly anisotropic. Simulations are made by the finite-difference time-domain method (FDTD), which is a numerical approach for the rigorous solution of the Maxwell equations. This method, in contrast to methods of geometrical and matrix optics, delivers results which include diffraction and scattering.

关键词： liquid crystal gratings anisotropic gradient index media light propagation finite-difference time-domain method

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Ultra-wide band signal analysis in urban environment

Ultra-wide band signal analysis in urban environment

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Conference on Digital Wireless Communications IV

作者： Schiavone, G Palaniappan, R Tracy, J Wahid, P Dere, T Univ Cent Florida Dept Comp Sci Orlando FL 32826 USA

"UItra-wide band" (UWB) is a relatively new term used to describe a technology that has been known since the 1960's as "carrier free", "baseband" or "impulse" technology. Th... 详细信息

ISBN: (纸本)0819444901

"UItra-wide band" (UWB) is a relatively new term used to describe a technology that has been known since the 1960's as "carrier free", "baseband" or "impulse" technology. The basic concept is to develop, transmit and receive an extremely short duration burst of radio frequency energy-typically a few tens of pico seconds to a few nanoseconds in duration. The resultant waveforms are extremely broadband, so much so that it is often difficult to determine an actual RF center frequency- thus the term "carrier free". Since UWB waveforms are of such short time duration, they have some rather unique properties. In communications, for example, UWB pulses can be used to provide extremely high data rate performance in multi-user network applications [1]. For radar applications, these same pulses can provide very fine range resolution and precision distance and/or positioning measurement capabilities. These short duration waveforms are relatively immune to multi-path cancellation effects as observed in mobile and in-building environments. As a consequence, UWB systems are particularly well suited for high-speed, mobile wireless applications. As bandwidth is inversely related to pulse duration, the spectral extent of these waveforms can be made quite large. With proper engineering design, the resultant energy densities (i.e., transmitted watts of power per unit hertz of bandwidth) can be quite low. This low energy density translates into a low probability of detection (LPD) RF signature. An LPD signature is of particular interest for military applications (e.g., for covert communications and radar);however, an LPD signature also produces minimal interference to proximity systems and minimal RF health hazards, significant for both military and commercial applications. In this paper we consider the development of a simulation model to calculate ultra-wide band signal propagation characteristics in urban indoor and outdoor environments. The simulation is accomplished using a hybrid

关键词： finite-difference time-domain method Ray tracing Fourier transforms 3D modeling Computer simulations Transmitters Buildings Laser phosphor displays Signal to noise ratio Telecommunications

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A 2D-Transmission line model for the EM field estimation inside enclosures with apertures

A 2D-Transmission line model for the EM field estimation ins...

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IEEE International Symposium on Electromagnetic Compatibility

作者： Belokour, I LoVetri, J Visteon Corp Dearborn MI 48120 USA

ISBN: (纸本)0780372646

The development of efficient phenomenological models which give accurate estimates for the coupling of electromagnetic energy through apertures and into enclosures is important for the EMC design of almost all electronic subsystems. It has been previously shown that a simple analytical transmission line formulation gives good predictions of the dominant mode TEl0 as well as higher-order modes TEln0 inside a rectangular enclosure with apertures. In this work the model is extended to include a two-dimensional set of transverse electric modes TEmn in the transmission line (TL) model. The rectangular enclosure with aperture is represented as a intersection of two orthogonal transmission lines, one for each set of transverse electric modes. The model remains very, simple and computationally efficient. The finite difference time-domain (FDTD) method is used to validate the results.

关键词： phenomenological model 2D-transmission line electro-magnetic energy metal enclosure aperture transverse electric mode finite-difference time-domain method

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Analysis of upsets and failures due to ESD by the FDTD-INBCs method

Analysis of upsets and failures due to ESD by the FDTD-INBCs...

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Annual Meeting of the Industry-Applications-Society

作者： Maradei, F Raugi, M Univ Roma La Sapienza Dept Elect Engn I-100184 Rome Italy Univ Pisa Dept Elect Engn & Automat I-56126 Pisa Italy

ISBN: (纸本)0780364015;0780364023

In this paper, a finite-difference time-domain (FDTD) model of an electrostatic discharge (ESD) event is developed. Analytical expressions for the field radiated during the ESD discharge phase have been determined to test the FDTD model of the strike arc. In order to take into account the electromagnetic field penetration through shielding structures, the conductive panels are efficiently modeled in the FDTD by the impedance network boundary conditions (INBCs). The FDTD-INBCs method avoids the huge amount of cells needed to model accurately the penetration in the traditional FDTD algorithm based on the utilization of the regular Yee grid. The method is applied to the analysis of ESD events in some configurations.

关键词： electrostatic discharge finite-difference time-domain method impedance network boundary conditions

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Composite effects of reflections and ground bounce for signal line through a split power plane

Composite effects of reflections and ground bounce for signa...

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10th Topical Meeting on Electrical Performance of Electronic Packaging

作者： Wu, CT Shiue, GH Lin, SM Wu, RB Natl Taiwan Univ Grad Inst Commun Engn Dept Elect Engn Taipei 106 Taiwan

The signal propagating along a microstrip line over a slot on the power plane will suffer from composite effects of reflected noise by a discontinuity in signal return path and ground bounce between power and ground planes. A new equivalent circuit model is proposed and simulations are performed for multilayer structures to characterize these composite effects. An experimental setup is devised to demonstrate significant coupling between signal lines due to the slot-induced ground bounce. Favorable comparison between the simulation and measured results validates the proposed equivalent circuit model and analysis approach.

关键词： finite-difference time-domain method ground bounce printed circuit board signal integrity slot voltage island

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Lifetime of optical modes in two dimensionally ordered spheres

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 2002年第1期41卷 149-154页

作者： Haraguchi, M Fukui, M Okamoto, T Shinya, A Univ Tokushima Fac Engn Dept Opt Sci & Technol Tokushima 7708506 Japan

We have numerically calculated the lifetimes of optical modes, e.g., a propagating mode, in two-dimensionally (2D) ordered spheres on a glass substrate using a finite-difference time-domain method. The lifetimes of the optical modes excited by the evanescent light in an attenuated total reflection (ATR) geometry are much shorter than those excited by a light source embedded in the 2D ordered spheres on substrates. The spatial distributions of the light intensity associated with the optical modes excited in the ATR geometry are found to be different from those in the case of the embedded light source. The light energy of the optical modes excited in the ATR geometry flows extending over the entire the respective spheres and thus can be easily coupled out through the prism. On the other hand, the light energy associated with the optical modes excited by the embedded light source flows straight around the central axis of spheres, leading to a longer life time.

关键词： ordered spheres microsphere lifetime light propagation light coupling evanescent light attenuated total reflection finite-difference time-domain method

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Application of the concurrent complementary operators method to numerically derived absorbing boundary conditions

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2002年第4期32卷 272-275页

作者： Wu, X Ramahi, OM Univ Maryland A James Clark Sch Engn College Pk MD 20742 USA

The concurrent complementary operators method (C-COM) has been demonstrated to be it highly effective mesh truncation technique for the simulation of electromagnetic open-region transient or time-harmonic problems. In previous work, the C-COM was applied to analytically derived absorbing boundary conditions (ABCs). In this work, we show that the C-COM can be applied to the wider class of highly effective and versatile numerically derived ABCs. As a demonstration of the validity of this generalization, we consider the case of a Liao ABC, and show their high accuracy can be obtained. (C) 2002 John Wiley Sons, Inc.

关键词： absorbing boundary conditions complementary operators method finite-difference time-domain method

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Refractive behavior of 2D square lattice photonic crystals determined by reducing the symmetry of the unit cell

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 2002年第11A期41卷 6375-6379页

作者： Takayama, Y Klaus, W Commun Res Labs Koganei Tokyo 1848795 Japan

We studied the refractive behavior of two-dimensional (2D) photonic crystals consisting of rods with a rectangular cross section. All crystals treated in this work are assumed to have the same lattice constant. By modifying only the rod's side ratio, we found that negative or positive anisotropic refractive behavior or a photonic band gap can be observed. This behavior is confirmed by using a rigorous electromagnetic theory, namely, the finite-difference time-domain (FDTD) method. By taking advantage of this behavior, we furthermore combined crystals with different properties, and showed that the smooth conjunction produced by the same lattice constant allows each part of the combined crystal to keep its refractive property as if each part were treated individually.

关键词： photonic crystals anisotropic refractive behavior photonic band gap finite-difference time-domain method

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