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Electromagnetic Compatibility, IEEE Transactions on

Issue 2 • Date May 1989

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Displaying Results 1 - 19 of 19
  • An evaluation of a radiofrequency protective suit and electrically conductive fabrics

    Publication Year: 1989 , Page(s): 129 - 137
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    A protective suit consisting of an overall with an integral hood, gloves, and oversocks, constructed of an electrically conductive fabric, has been examined theoretically and experimentally for electromagnetic shielding effectiveness (SE) at radio frequencies (RF) in the range from 200 kHz to 4 GHz. The suit, although originally developed to provide personnel protection in large electric-field gradients near overhead high-voltage 50/60 Hz power transmission lines, was claimed to provide whole-body protection for RF workers. The authors describe the methods of measurement used and the experimental and theoretical results obtained, and provide details of the deficiencies in SE of the suit. In particular, it is shown that resonant enhancement of RF fields can occur in the head region at microwave frequencies, and that no attenuation is provided for magnetic fields at frequencies below about 4 MHz. Minimum design criteria to be observed in any such suits that may be developed in the future are proposed.<> View full abstract»

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  • A new sectioning procedure for calculating scattering and absorption by elongated dielectric objects

    Publication Year: 1989 , Page(s): 157 - 163
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The iterative extended boundary condition method (IEBCM) has recently been developed to calculate scattering and absorption by elongated dielectric objects. The authors present a new sectioning procedure to improve the computational efficiency of the IEBCM. In this technique, the total geometry of the object is divided into overlapping sections, each of which includes only 3-5 spherical expansions to describe the internal fields. The total number of expansions required to describe the internal fields in the overall object may be as large as 15. Results illustrating the improvement in the computational efficiency of the IEBCM, as well as the dependence of the minimum number of expansions that should be included in each section on the dielectric properties of the scatter and on the frequency, are presented. It is shown that the sectioning procedure is particularly useful at frequencies below (ka<3) and above the resonance frequency of the object (4> View full abstract»

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  • Impact of non-Gaussian impulsive noise on the performance of high-level QAM

    Publication Year: 1989 , Page(s): 177 - 180
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (298 KB)  

    The impact of non-Gaussian impulse noise (Middleton's class A noise) combined with Gaussian thermal noise on the performance of high-level QAM (quadrature amplitude modulation) (e.g., 16, 64, and 256 QAM) systems is analyzed. The P(e) (probability of error) performance of the system is evaluated in terms of CNR (carrier-to-noise ratio), impulsive index (A) of the noise, and power ratio of the Gaussian noise to the impulsive noise ( Gamma '). It is shown that, in the high-level QAM, non-Gaussian impulsive noise degrades the system performance significantly, even at high CNR. It is also found that an upper bound on the error probability exists for Gamma '> View full abstract»

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  • A quasi-static technique for evaluation of pigtail connections

    Publication Year: 1989 , Page(s): 180 - 183
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB)  

    It is shown that the analysis of 'pigtail' connections between a transmission line and a ground plane can be simplified by dividing the problem into two parts: the radiating transmission line and the pigtail loop. The problem need be solved only once by the moment method code for several different pigtail geometries. The effect of the pigtail can be taken into account quite accurately through the use of a quasi-static evaluation of pigtail loop inductance. The approximation is valid as long as the pigtail loop (with image) is less than a quarter wavelength in circumference.<> View full abstract»

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  • Methods for calculating the electromagnetic fields from a known source distribution: application to lightning

    Publication Year: 1989 , Page(s): 183 - 189
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (578 KB)  

    Two different techniques (monopole and dipole) for calculating the electric and magnetic fields from a distribution of currents and charges are discussed. Both techniques have been used for calculating the fields from lightning. A simple lightning return stroke current model, consisting of a square current pulse traveling up a vertical antenna above a ground plane, is used to compare the two techniques. Analytical expressions are obtained for the fields using each technique. These expressions are shown to be numerically equivalent, but the authors are unable to prove their equivalence analytically. It is concluded that the monopole and the dipole techniques can both be derived from Maxwell's equations and hence that both are correct. In attempting to dispel the apparent confusion that has existed regarding the validity of the monopole technique, the authors show that the monopole approach, as discussed in the literature, is applicable only to upward-traveling current waves and hence is not particularly useful in the realistic modeling of lightning return strokes.<> View full abstract»

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  • Comments on "Solutions of Maxwell's equations for general nonperiodic waves in lossy media" by M.E. El-Shandwily

    Publication Year: 1989 , Page(s): 197 - 199
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The commenter notes that the intention of M.E. El-Shandwily's paper (see ibid., vol.30, no.4, p.577-82, Nov. 1988) is to demonstrate that the linear Maxwell's equations can be applied to the case of a pulse or step-function field change. If this can be demonstrated, then, it is claimed, the Harmuth Ansatz (see ibid., vol.EMC-28, no.4, p.250-8, Nov. 1986) for solving Maxwell's equations to obtain the magnetic field for impulse excitation is unnecessary. The commenter seeks to show that El-Shandwily actually implements the Harmuth Ansatz, which explains the concurrence of Harmuth's and El-Shandwily's predictions.<> View full abstract»

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  • Comments on a short paper by El-Shandwily on transient solutions of Maxwell's equations

    Publication Year: 1989 , Page(s): 199 - 200
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    The commenter claims that M.E. El-Shandwily (see ibid., vol.30, no.4, p.577-82, Nov. 1988) made four mistakes in obtaining his results, namely the belief that Dirac's delta function integrated from zero to infinity has a defined value, the attempt to derive solutions of a system of partial differential equations interpreted for distributions without a method that is known to yield uniform convergence, to disregard for the fact that Maxwell's equations are a mathematical model of physical phenomena, and the belief that the need to modify Maxwell's equations is a topic for serious scientific discussion.<> View full abstract»

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  • Comments on "Some comments on Harmuth and his critics" by J.E. Gray and S.P. Bowen

    Publication Year: 1989 , Page(s): 201 - 202
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    J.E. Gray and S.P. Bowen (see ibid., vol.30, no.4, p.586-9, Nov. 1988) claim to have developed the formalism necessary to solve the propagation of pulses in a lossy medium for both the magnetic and electric fields using the Laplace transformation and generalized functions. They claim that Harmuth's introduction of the magnetic current s, is neither necessary nor a sufficient reason to insure consistency and that their method permits calculating both the electric and magnetic fields uniquely for a wide variety of pulses. The commenter claims, however, that Gray and Bowen introduce covert assumptions that deny their claim.<> View full abstract»

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  • Comments on "In defense of J.A. Stratton" by J.R. Wait

    Publication Year: 1989
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (123 KB)  

    Comments are made on the above-named work (see ibid., vol.30, no.4, p.590, Nov. 1988). Attention is given to whether Stratton considered the problem of obtaining solutions of the complete electromagnetic fields for transients in lossy media trivial.<> View full abstract»

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  • Comments on "Solutions of Maxwell's equations for general nonperiodic waves in lossy media" by M.E. El-Shandwily

    Publication Year: 1989 , Page(s): 202 - 204
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (257 KB)  

    The commenter claims that the solutions obtained by M.E. El-Shandwily (see ibid., vol.30, no.4, p.577-82, Nov. 1988) are incorrect. The commenter argues that the steps followed by El-Shandwily in deriving them only prove that Maxwell's equations in their usual forms cannot provide the desired solutions for signal propagation in lossy media.<> View full abstract»

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  • Theoretical considerations for optimal positioning of peaking capacitor arms about a Marx generator parallel to a ground plane

    Publication Year: 1989 , Page(s): 117 - 124
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    The authors develop theoretical considerations useful in determining the electromagnetically optimal positions for a specified number of peaking-capacitor arms about a Marx generator parallel to a ground plane. It is shown that this can be determined by a conformal transformation. A parameter is defined and computed that is indicative of the effectiveness of the peaking-capacitor arms in shielding the Marx from the ground plane. The results of interest in connection with determining the hardness of systems to a nuclear electromagnetic pulse environment View full abstract»

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  • Application of block pulse functions for digital protection of power transformers

    Publication Year: 1989 , Page(s): 193 - 196
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    The author describes an application of block pulse functions for digital protection of power transformers. Digital relay algorithms are developed to extract fundamental and second-harmonic components. These components are then used for harmonic restraint differential protection of transformers. In comparison with the algorithms based on the Walsh and Haar functions, the proposed method is computationally simple and can be used with any sampling frequency. It is concluded that offline testing of the method with simulated inrush and internal fault current data clearly indicate that the method can provide fast and reliable trip decision. The method is suitable for microprocessor-based protective relays View full abstract»

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  • Adaptive filtering using the fast Walsh-Hadamard transformation

    Publication Year: 1989 , Page(s): 125 - 128
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    A fast implementation of the least-mean-square error (LMS) adaptive transversal filter is proposed. The fast Walsh-Hadamard transform technique is adopted in this implementation. This filter is shown to promise a significant reduction in computation over both the conventional time-domain and the frequency-domain LMS adaptive filters View full abstract»

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  • The effect of an electrically large stirrer in a mode-stirred chamber

    Publication Year: 1989 , Page(s): 164 - 169
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    In a mode-stirred chamber, the field in the cavity is perturbed with a stirrer or rotating scatterer so that the time-averaged field is constant. The authors investigate the key factor that governs the effectiveness of a stirrer. By examining the fundamental properties associated with a perturbing body in a cavity, they find that the key to effective field perturbation lies in shifting the eigenmode frequencies. They illustrate this phenomenon by examining a two-dimensional cavity with a one-dimensional perturbing body. Using the transmission-line-matrix method, they compute the shifting of eigenfrequencies and examine the variation on the magnitude of the fields for different stirrer sizes. From this analysis, they draw an analogy between the action of a large stirrer and the effect of amplitude and frequency modulations. It is concluded that it is theoretically possible to simulate the stirrer by the external modulation of the input signal View full abstract»

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  • Radar equation for nonsinusoidal waves

    Publication Year: 1989 , Page(s): 138 - 147
    Cited by:  Papers (2)
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    The well-known radar equation for sinusoidal waves is extended to apply to nonsinusoidal waves, in particular to binary waves with the two values ±E and ±H for the electric- and magnetic-field strength during signal transmission. Three major modifications have to be made: the concept of radar cross section is changed; the gain of the radiating antenna and the resolution angle of the receiving antenna are different from the values holding for sinusoidal waves; and the effect of noise is modified, primarily due to the absence of a rectifier View full abstract»

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  • A comparison of the contributions of common-mode and differential-mode currents in radiated emissions

    Publication Year: 1989 , Page(s): 189 - 193
    Cited by:  Papers (119)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    It is shown that radiated emissions due to common-mode currents on printed circuit board lands can greatly exceed those due to differential-mode currents. It is concluded that predictions of radiated emissions based solely on differential-mode (transmission line) currents can bear little, if any, resemblance to actual measured emissions. Therefore, radiated emission prediction models that use only differential-mode (transmission-line) currents and ignore common-mode (antenna) currents are not adequate for the prediction of radiated emissions from printed circuit boards (as well as cables) View full abstract»

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  • Transients on the mains in a residential environment

    Publication Year: 1989 , Page(s): 170 - 176
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    A digital oscilloscope was used to measure transients on the single-phase 120 V RMS mains in a residential environment. Naturally occurring transient voltages between the hot conductor and ground and between the neutral conductor and ground were recorded simultaneously. Each record contains 1024 samples taken at the rate of 10 samples/μs. Waveforms are shown for transient overvoltages on the mains caused by three nearby lightning strikes and one unknown source. Statistical summaries are presented for all naturally occurring transients. It is shown that the common-mode voltage is often larger than the differential-mode voltage. Waveforms from deliberately switching common appliances were recorded at various sample rates between 100 and 1.0 sample/μs. Waveforms are presented for the transient caused by switching on a resistive load, e.g. a tungsten lamp. This transient can have a slope at least as large as 6 kV/μs and may cause problems, although the effect of this type of transient is always to decrease the magnitude of the voltage. Waveforms are also shown for switching the motor in a vacuum cleaner, which has a slope as large as 17 kV/μs View full abstract»

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  • Reply to Comments on Maxwell's equations by J.E. Gray and S.P. Bowen

    Publication Year: 1989 , Page(s): 200 - 201
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    J.E. Gray and S.P. Bowen (see ibid., vol.30, no.4, p.586-9, Nov. 1988) use a modification of Maxwell's equations by substituting distributions for functions differentiable in the sense of Leibnitz and Newton. The commenter notes that the work of Gray and Bowen confirms what he has claimed previously, i.e. that Maxwell's equations must be modified. The commenter then considers which modification(s) can explain all the experimental results that the current theory cannot explain View full abstract»

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  • A model for fast switching transients in power systems: the near zone concept

    Publication Year: 1989 , Page(s): 148 - 156
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    The author presents a simple time-domain model which makes it possible to predict the order of magnitude of the highest di/ dt values generated by closing switches in electrical power systems. The model is based on traveling-wave analysis. It is demonstrated that two different approaches must be applied, according to whether (a) the closing time, Ts, of the switch is faster than twice the traveling time to the first reflection point or (b) Ts is much slower. Under condition (b) the well-known quasistationary approach di/dtmax=U0/L can be used, where U0 is the switched voltage and L is the self-inductance of the line between the stray capacitances located to the left and the right of the switching device. Under condition (a) a new formula must be applied: di/dt max≈2 U0/ZTs, where Z is the line impedance of the line in which the switching device is installed and Ts is the time during which the voltage across the switch collapses from U0 to zero. Experimental results are given from both fast and slow closing switches 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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Professor Farhad Rachidi
Swiss Federal Institute of Technology (EPFL)
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Fax: +41 (0) 21 693 46 62
Email: Farhad.Rachidi@epfl.ch
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