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Electromagnetic Compatibility, IEEE Transactions on

Issue 1 • Date Feb. 2003

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Displaying Results 1 - 19 of 19
  • Comments on "Investigation of the field uniformity of a mode-stirred chamber using diffusors based on acoustic theory"

    Page(s): 146 - 147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (185 KB)  

    In the above paper [see ibid., vol. 41, p. 446-51, 1999] a particular type of reflection grating, viz., Schroeder diffusers of the quadratic-residue type (QRDs), was proposed with the aim of improving field uniformity inside mode-tuned or mode-stirred reverberation chambers. While an improvement of the field homogeneity (but not necessarily the field isotropy) was demonstrated, some facts about the design and application of this type of pseudorandom diffractor (PRDs) appear to have been overlooked. View full abstract»

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  • Voltage induced on a test distribution line by negative winter lightning strokes to a tall structure

    Page(s): 135 - 140
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    Simultaneous measurements of lightning-induced voltages and lightning currents are presented and subject to analysis. The lightning current was measured at the top of a 200-m high stack by a current shunt. In the analysis, both the transmission-line model (TLM) and traveling current-source model (TCSM) of a return stroke are tested, taking account of reflection and refraction of the lightning current waves at the top and bottom of the stack. Analysis shows that the measured induced voltages on a test distribution line were influenced by finite ground conductivity. Agreement of measured induced-voltage waveforms with calculations demonstrates the validity of the adopted models of the stack and the lightning stroke. Both TLM and TCSM turn out to be useful in predicting induced voltage associated with a negative lightning stroke to a tall structure in winter. View full abstract»

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  • Analytical formulation of lightning-induced voltages on multiconductor overhead lines above lossy ground

    Page(s): 92 - 100
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    This paper presents analytical expressions for calculation of lightning-induced voltages (LIV) on multiconductor overhead lines above lossy ground. The transmission-line return-stroke model is used and the propagation effect on the electromagnetic field is approximated by the surface impedance method. Assuming a linear return-stroke current, the standard numerical integrations along the lightning channel and the overhead line are avoided, and the result is a fast and stable formulation that contains only a single convolution integral. The described method applies for distances between 100 m and 10 km and is valid the first few microseconds where the maximum LIV usually occurs. A simplified approach to how to include overhead line losses is also outlined. A model is proposed that can be included in the electromagnetic transients program ATP-EMTP for calculation of LIV in larger and practical systems. View full abstract»

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  • On the concepts used in return stroke models applied in engineering practice

    Page(s): 101 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB) |  | HTML iconHTML  

    In this paper, we investigate the similarities between two basic concepts used in engineering return stroke models. In one type, the current propagation (CP) models, the return stroke channel merely acts as a medium for the current propagation with the driving source being at the ground. In the other type, the current generation (CG) models, the current sources (corona current) are assumed to be distributed along the return stroke channel. Our analysis shows that popular CP models, such as transmission line (TL), the modified transmission-line exponential (MTLE) model , and the modified transmission-line linear (MTLL) can be converted to CG models leaving the temporal and spatial variation of the return stroke current the same. In this alternative representation, the equivalent corona currents of the TL, MTLE, and MTLL models are bipolar, indicating initial deposition and subsequent removal of positive charge from the channel. This knowledge is applied to construct a simple CG model which generates electromagnetic fields identical to those obtained with the TL model at short times, but free from the difficulties associated with the latter at longer times. View full abstract»

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  • Investigation into the interference potential of spread-spectrum clock generation to broadband digital communications

    Page(s): 10 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (878 KB) |  | HTML iconHTML  

    Since its inception, spread-spectrum clocks have been a valuable technology for the purposes of EMI reduction and EMC compliance. This study evaluates the interference potential of spread spectrum clocks to broadband digital communications such as high definition television (HDTV). This is accomplished by comparing the spread spectrum clock interference susceptibility of digital television (DTV) receivers to the interference susceptibility of analog television receivers. This study shows that DTV receivers are more immune to the same level of interference than existing analog television receivers by 16 dB. Since industry has shown that analog television has had negligible interference from information technology equipment, including spread spectrum clocks, then the digital systems should have even less. View full abstract»

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  • Frequency- and time-domain modeling of the transfer impedance and distributed longitudinal induced voltage by means of a SPICE equivalent circuit

    Page(s): 125 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (449 KB) |  | HTML iconHTML  

    Frequency- and time-domain expressions for the transfer impedance of single conductor shielded cables are proposed. The time-domain convolution needed for the evaluation of the distributed longitudinal voltage induced on the internal conductor of the cable is directly evaluated by means of an equivalent SPICE circuit that can be incorporated in already existing shielded coaxial cables circuit models. View full abstract»

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  • Power-bus decoupling with embedded capacitance in printed circuit board design

    Page(s): 22 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (891 KB) |  | HTML iconHTML  

    This paper experimentally investigates the effectiveness of embedded capacitance for reducing power-bus noise in high-speed printed circuit board designs. Boards with embedded capacitance employ closely spaced power-return plane pairs separated by a thin layer of dielectric material. In this paper, test boards with four embedded capacitance materials are evaluated. Power-bus input impedance measurements and power-bus noise measurements are presented for boards with various dimensions and layer stack ups. Unlike discrete decoupling capacitors, whose effective frequency range is generally limited to a few hundred megahertz due to interconnect inductance, embedded capacitance was found to efficiently reduce power-bus noise over the entire frequency range evaluated (up to 5 GHz). View full abstract»

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  • Theoretical investigation of the field conditions in a vibrating reverberation chamber with an unstirred component

    Page(s): 77 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    In this paper, we examine the use of a vibrating reverberation chamber in which an equipment under test (EUT) is directly illuminated by a source antenna. A three-dimensional theoretical model, based on a simplified ray tracing method has been applied on a reverberation chamber whose dimensions were varied. The field distribution together with the field homogeneity was investigated, introducing the Rice distribution due to the presence of the line-of-sight component between the antenna and the EUT. View full abstract»

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  • Computation of transmission-line immunity level in the presence of a direct-sequence spread-spectrum electromagnetic signal by using CE-FDTD method

    Page(s): 2 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (703 KB) |  | HTML iconHTML  

    A method is introduced for the quantitative determination of the interference level, originated by a direct-sequence (DS) spread-spectrum electromagnetic signal, impinging a two-wire transmission line (TL) on which a similar information signal is driven by a lumped voltage source. The model presented makes use of a properly modified, second-order accuracy finite-difference time-domain (FDTD) algorithm, the so-called complex-envelope (CE) FDTD, incorporating the principle concept of the DS code division multiplex access method. Moreover, this paper examines the advantages arising from the use of the CE representation of the final FDTD expressions, allowing for an accurate solution of the electromagnetic interference (EMI) problem by partially avoiding the computational burden of the classic FDTD approach. Numerical results for several general cases are presented, providing valuable information for the comprehension of the influence of the amplitude and angle of incidence of the interfering signal to the TL behavior. View full abstract»

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  • Human equivalent antenna model for transient electromagnetic radiation exposure

    Page(s): 141 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    Thin-wire antenna model of the human body exposed to the transient excitation is presented in the paper. The analysis is based on the solution of the corresponding integral equation and it is carried out directly in the time domain (TD) . The integral equation is handled via the TD Galerkin-Bubnov scheme of the boundary element method. Numerical results are presented for the time-harmonic and transient exposures. View full abstract»

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  • The antennas on a mobile board and their electromagnetic compatibility

    Page(s): 119 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    This paper presents the solutions of a problem of optimization in the decrease of antenna-coupling coefficients on a mobile board in case of limitations on coverage for each antenna. To determine a minimum value of an antenna-coupling coefficient for one pair of antennas, we use the Gauss-Zeidel optimization method or search method. When two or several antenna pairs have a common antenna, the coordinates of this antenna are determined by the compromise. The algorithms of optimum antenna placement are supported by the computer software and are tested for a case of four antennas. View full abstract»

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  • Characteristics of lightning surges induced in telecommunication center in tropical area

    Page(s): 82 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (950 KB) |  | HTML iconHTML  

    The characteristics of lightning-induced surges in telecommunication equipment due to a direct lightning strike at a telecommunication center building or tower should be investigated to maintain the reliability of advanced telecommunication systems. In particular, investigations in tropical areas are important because these areas have many thunderstorm days. We observed lightning surges induced in a telecommunication building in Kuala Lumpur, Malaysia. The results show that the peak value occurrence frequency and waveforms of direct strike lightning surges were almost the same as those in a temperate area. The peak current relationships between the cables in the building and the tower legs indicate a strong correlation between the current at the tower legs, waveguide, power line, and outer and inner conductors of the coaxial cables. However, the peak value correlations between the tower leg currents and interface cable voltages were not strong. Based on the observation results, we obtained the correlation factors between the peak value at the observation point and the tower legs, and calculated the peak value at the interface cables as a function of the number of thunderstorm days. View full abstract»

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  • Characteristics of electromagnetic return-stroke models

    Page(s): 129 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    Impedance and associated electromagnetic (EM) fields of an EM return-stroke model are investigated with the help of NEC-2. The impedance of a cylindrical vertical conductor increases with time. The impedance of a vertical conductor having additional distributed inductance is initially 700 to 1000 Ω for the current propagation velocity ranging from 170 to 130 m/μs. This is in good agreement with the apparent impedance of a lightning channel, estimated from lightning-current waveforms measured at the top and bottom of tall towers. A model considering a horizontally bent channel in a thundercloud succeeds in reproducing all of the established features of measured field waveforms except the hump of close magnetic field, while a vertically straight conductor fails to reproduce two of the features. View full abstract»

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  • Analysis and Simulation of a 1-18-GHz broadband double-ridged horn antenna

    Page(s): 55 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1031 KB) |  | HTML iconHTML  

    A 1-18-GHz broadband double-ridged horn antenna with coaxial input feed section is investigated. For the ridged horn antenna it is found that the radiation pattern, contrary to common belief, does not maintain a single main lobe in the direction of the horn axis over the full frequency range. Instead, at frequencies above 12 GHz, the main lobe in the radiation pattern starts to split into four large side lobes pointing in off-axis directions with a dip of up to 6 dB between them along the main axis. Although this type of horn is the preferred test antenna, which is in common use for over four decades, no explanation for this unwanted behavior was found in the open literature. To investigate this phenomenon in detail, a method of moments approach has been adopted to simulate the complete antenna system. The simulations are in good agreement with the measurements over the 1-18-GHz operational bandwidth and indicate that the use of this type of horn antenna in EMC applications remains questionable. View full abstract»

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  • Reciprocity in reverberation chamber measurements

    Page(s): 117 - 119
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (234 KB) |  | HTML iconHTML  

    Even though reverberation chambers have been used primarily for radiated immunity testing, they are reciprocal devices that are equally applicable for radiated emissions testing. This short paper presents the theory for radiated emissions testing and uses electromagnetic reciprocity theory to demonstrate the link between radiated emissions and immunity testing. View full abstract»

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  • Statistics of the quality factor of a rectangular reverberation chamber

    Page(s): 61 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1217 KB) |  | HTML iconHTML  

    The mean and standard deviation of the theoretical quality (Q) factor of a rectangular reverberation chamber are considered. Different averaging methods are investigated for deriving alternative expressions for its bandwidth-averaged value. Alternative basic assumptions are made regarding the distribution of the total energy density inside the cavity across the participating eigenmodes, thus providing alternatives for the assumption of equipartition of excitation energy. The physical reasons for such possible departures are explained on the basis of the stored and dissipated modal energy. For a given volume-to-surface ratio of a rectangular cavity, the theoretical arithmetic average Q (unlike the harmonic average) exhibits an explicit asymptotic dependence on the aspect ratios of the cavity. In the asymptotic high-frequency limit, the first-order dependence of the arithmetic Q on inverse frequency is governed by the imbalance between the TM and TE quality factors and by the aspect ratios of the cavity. Simulation results indicate better agreement between actual and smoothed theoretical arithmetic averages, particularly at lower frequencies, in comparison with those for the harmonic mean values. An expression for the distribution function of the arithmetic Q is formulated based on its statistical moments. We furthermore analyze the Q of a chamber with dynamically varying walls but constant average mode density. Such a chamber may serve as a model for mode stirring using flexible walls. The existence of a mode bunching effect which varies with tuner state but stabilizes with increasing frequency is shown. Effects of continuous dynamics of the cavity deformation on Q are discussed. View full abstract»

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  • Long-cable effects on conducted emissions levels

    Page(s): 43 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    A novel frequency-domain distributed-parameter circuit model of the setup for the measurement of conducted emissions (CE) in three-conductor systems is developed in order to predict the effects that an electrically-long power cord connecting the equipment under test (EUT) to the line-impedance stabilization network (LISN) plays on CE levels. To this end, a three-conductor lossless and uniform transmission line model is adopted for the description of the power cord, and modal decomposition of the line voltages and currents to common- and differential-mode voltages and currents is used to derive new closed-form expressions of the CE at the LISN ports. Suitable EUT-to-LISN matrix transfer functions are introduced and it is shown that CE measured at the entrance of the power outlet (i.e., at the LISN ports) may differ significantly from those flowing out of the EUT mains ports, due to propagation and coupling along the power cord. The role played by the mains cable cross section on CE propagation and conversion is investigated, and upper/lower bounds for the power cord effects on CE are derived analytically by applying an asymptote plot analysis to the magnitude of the EUT-to-LISN transfer functions. Direct numerical solution of the transmission line model is used to validate the obtained literal expressions of CE and related bounds, as well as to give explicit indications about the impact of long-cable effects on CE. View full abstract»

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  • Temperature increase in the human head due to a dipole antenna at microwave frequencies

    Page(s): 109 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (423 KB) |  | HTML iconHTML  

    The temperature increases in a human head due to electromagnetic (EM) wave exposure from a dipole antenna are investigated in the frequency range of 900 MHz to 2.45 GHz. The maximum temperature increases in the head and brain are compared with the values of 10°C and 3.5°C (found in literature pertaining to microwave-induced physiological damage). In particular, the estimation scheme for maximum temperature increases of the head and brain tissues is discussed in terms of a peak average specific absorption rate (SAR) as prescribed in safety standards. The rationale for this attempt is that maximum temperature increases and peak average SARs have not been well correlated yet. For this purpose, the SAR in the head model is initially calculated by the finite-difference time-domain method. The temperature increase in the model is then calculated by substituting the SAR into the bioheat equation. Numerical results demonstrate that the temperature increase distribution in the head is largely dependent on the frequency of EM waves. This is mainly because of the frequency dependency of the SAR distribution. Similarly, maximum temperature increases in the head and brain are significantly affected by the frequency and polarization of the EM wave. The maximum temperature increases in the head (excluding auricles) and brain are determined through linear extrapolation of the peak average SAR in these regions. According to this scheme, it is found that the peak SAR averaged over 1 g of tissue in the head should be approximately 65 W/kg to achieve the maximum temperature increase of 10°C induced in the head excluding auricles. This corresponds to a factor of about 40 compared to the FCC standard. On the other hand, the peak SAR for 10 g of tissue should be around 40 W/kg, which implies a factor of about 20 compared to the ICNIRP standard. View full abstract»

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  • Hybridization of FDTD and device behavioral-modeling techniques [interconnected digital I/O ports]

    Page(s): 31 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    We present a systematic methodology for the electromagnetic modeling of interconnected digital I/O ports. Digital drivers and receivers are represented through behavioral models based on radial basis functions expansions. Such a technique allows a very accurate representation of nonlinear/dynamic effects as well as switching behavior of real-world components by means of carefully identified discrete-time models. The inclusion of these models into a finite-difference time-domain solver for full-wave analysis of interconnected systems is presented. A rigorous stability analysis shows that use of nonlinear/dynamic discrete-time models can be easily integrated with standard full-wave solvers, even in the case of unmatched sampling time. A set of numerical examples illustrates the feasibility of this method. View full abstract»

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Aims & Scope

IEEE Transactions on Electromagnetic Capability publishes original and significant contributions related to all disciplines of electromagnetic compatibility (EMC) and relevant methods to predict, assess and prevent electromagnetic interference (EMI) and increase device/product immunity.

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Meet Our Editors

Editor-in-Chief
Professor Farhad Rachidi
Swiss Federal Institute of Technology (EPFL)
EMC Laboratory
CH-1015 Lausanne
Switzerland
Phone: +41 (0) 21 693 26 20 (direct)
+41 (0) 21 693 26 61 (secretariat)
Fax: +41 (0) 21 693 46 62
Email: Farhad.Rachidi@epfl.ch
url: http://emc.epfl.ch