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Electromagnetic Compatibility, IEEE Transactions on

Issue 3 • Date Aug 1999

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Displaying Results 1 - 14 of 14
  • Interaction of electromagnetic fields from cloud and ground lightning flashes with an artificial low-voltage power installation

    Page(s): 250 - 257
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    In most of the studies dealing with electromagnetic field interaction between nearby lightning flashes and electrical installations, the cloud flashes are assumed to play an insignificant role. However, our studies show that cloud flashes can generate induced voltages with amplitudes comparable to those of ground flashes when the electrical installation has a limited size or length and the lightning flash is a few tens of kilometers away. Furthermore, the voltages generated by cloud flashes have much shorter risetimes and pulse widths than those of ground flashes. This paper presents the results of a study conducted to investigate the coupling mechanism between lightning electromagnetic fields from both cloud and ground flashes and an artificial low-voltage power installation (LVPI). In the experiment, a Y-shaped artificial LVPI was constructed and exposed to lightning-electromagnetic fields. In the experiment, both the vertical electric field and the induced voltage in the LVPI were measured simultaneously. The analysis was conducted in the time domain by using the Alternative Transient Program-Electromagnetic Transient Program (ATP-EMTP) and the horizontal electric field at the installation was calculated by applying the concept of wavetilt to the measured vertical electric field. A reasonable agreement between the measured and simulated induced voltages was found. However, the results given in this study might not be true for longer structures such as power distribution lines and close lightning flashes View full abstract»

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  • Numerical and experimental study of the shielding effectiveness of a metallic enclosure

    Page(s): 202 - 213
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    This paper presents a detailed study of the shielding effectivity properties of metal enclosures. Measurements in anechoic chambers are compared to full-wave electromagnetic simulations. The study is not limited to the frequency range below the first resonance frequency. Different aspects are investigated such as the influence of the size, position and number of apertures, and the effect of the presence of metal plates and of absorbing materials. Where possible, the specific behavior of the shielding effectivity is explained theoretically and existing simple design rules are assessed View full abstract»

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  • Statistics of motor vehicle ignition noise at VHF/UHF

    Page(s): 257 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 KB)  

    Temporal sweeps of the amplitudes of electromagnetic vehicle ignition noise were made in Ottawa at six fixed frequencies in the range from 150 to 500 MHz using a 10 kHz bandwidth. Statistical analyses were performed of both the amplitude and temporal characteristics of the impulsive noise. The amplitudes approximately followed a lognormal distribution. The pulse spacings were uniformly distributed between about 5 and 15 ms and the pulse durations were about 150 μs long View full abstract»

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  • An automated SAR measurement system for compliance testing of personal wireless devices

    Page(s): 234 - 245
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    An automated specific absorption rate (SAR) measurement system has been developed for compliance testing of personal wireless devices. Unlike other systems, this system uses a model with a lossy ear-shaped protrusion and the accuracy of this experimental setup has been checked by comparing the peak 1-g SARs for ten cellular telephones, five each at 835 and 1900 MHz, with the results obtained using a 15-tissue anatomically based model with the finite-difference time-domain (FDTD) numerical electromagnetic technique. The SAR measurement system uses a three-dimensional (3-D) stepper motor to move a Narda Model 8021 E-field probe to measure the SAR distribution inside a head-shaped tissue-simulant phantom near the radiating device. The head and neck part of the model with an ear-shaped protrusion of 3 mm thickness is made of a lossy outer shell of 5-7 mm thickness of epoxy laced with KCl solution. The phantom is filled with appropriate frequency-specific fluids with measured electrical properties (dielectric constant and conductivity) that are close to the average for gray and white matters of the brain at the center frequencies of interest (835 and 1900 MHz). The implantable E-field probe is calibrated using the FDTD-calculated SAR variations for a slab model at two commonly used frequencies, 835 and 1900 MHz and is checked to have good isotropic characteristics (±0.23 dB) and a wide dynamic range (0.01-10 W/kg). The system is validated using a 223-mm-diameter sphere model. Peak 1-g SAR's for ten telephones using different antennas are within ±1 dB of those obtained using the FDTD numerical method for the anatomical model of the head and neck region View full abstract»

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  • Cosite interference between wire antennas on helicopter structures and rotor modulation effects: FDTD versus measurements

    Page(s): 221 - 233
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    As telecommunication systems become more complex and more antennas are placed on the same structure (e.g., helicopter airframe) the problem of interference becomes significant for the performance of the systems. The finite-difference time-domain (FDTD) method is used to calculate coupling between wire elements; e.g., monopoles and loops mounted on ground planes and helicopter airframes. Also, rotor modulation effects on coupling are investigated. All the numerical results obtained by FDTD are validated by comparison with measurements View full abstract»

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  • Highly improved performance of a noise isolation transformer by a thin-film short-circuit ring

    Page(s): 246 - 250
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    One of the typical phenomena observed during operations of transformers in general is the complex resonance phenomena present in high frequency ranges. Noise isolation (or cutout) transformers, which show the best performance among isolation devices, are not exempt from this difficulty, degrading their performance at high frequencies. The source of these resonance phenomena is a number of local spurious resonance circuits composed of various combinations of numerous minute stray capacitances and leakage inductances present in transformers, becoming apparent at higher frequencies. As a countermeasure against this difficulty, a short-circuit ring (made by an aluminum film) is placed near the coils inside a transformer. The effectiveness of this method is demonstrated experimentally by decreased resonance amplitudes and by 20-dB improvement of the overall attenuation level over an extended frequency range View full abstract»

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  • Time-domain study of a shielding cable system with a nonlinear load

    Page(s): 214 - 220
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    An impulse current of several kiloamperes was injected to the shield of a shielded cable, which was terminated by a varistor. The induced voltage on the inner conductor caused by this impulse current reaches an amplitude in excess of the varistor's threshold level. The clamped voltage across the varistor and the injected current have been studied for different termination conditions of the shielding cable. Furthermore, this paper also presents the use of a lumped circuit to simulate the transfer impedance of an “electrically short” shielded cable in the time domain. In combination with the varistor circuit model, the shielded cable with the nonlinear load, a varistor, was also simulated straightforwardly in the time domain. Good agreement was found between the measured voltage and current oscillograms and the calculated waveforms. It is thereby demonstrated the validity of the developed lumped circuit model for the transfer impedance of a shielded cable View full abstract»

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  • Induced voltages in a low-voltage power installation network due to lightning electromagnetic fields: an experimental study

    Page(s): 265 - 271
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    This paper presents experimental results on the induced common-mode (CM) voltages in a residential low-voltage power installation (LVPI) networks exposed to electromagnetic fields from lightning. The objective of this investigation was to find out the severity of induced voltages in a low voltage network due to direct coupling of the lightning electromagnetic fields with the network in the absence of transient overvoltages coming through the distribution lines. Flashes at a distance of about 25 km produced many induced-voltage pulses as large as 100 V, six such pulses in a time period of 0.4 ms in a negative CG flash, and 11 such pulses in a time period of 3 ms in a CC that immediately followed the ground flash View full abstract»

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  • A simple but effective way for cable shielding measurement

    Page(s): 175 - 179
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB)  

    The method of the current probe is used to recover the transfer parameters of coaxial cables. The measurements are carried out by means of only one current probe and using scalar instrumentation, resulting in a very simple and cheap setup compared with other techniques. This paper presents the relative theory showing that the assumption of weak coupling can be adopted; the results obtained for a typical cable are compared with that obtained by the triaxial technique and the line-injection method; a comparison is also performed with theoretical data obtained for the transfer impedance by several models View full abstract»

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  • An improved model for the electromagnetic compatibility of all-dielectric self-supporting fiber-optic cable and high-voltage power lines

    Page(s): 180 - 192
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    It has become common for utilities to locate optical-fiber communication systems on their transmission line towers. One type of cable used for this purpose is all-dielectric self-supporting (ADSS) cable, which is usually located below the phase conductors. Cables of this type have failed because of exposure to high electric fields. In this paper, a model is developed which can be used to establish the conditions for failure-free operation of ADSS cable View full abstract»

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  • Two-dimensional simulation of conducted currents characteristics in electrical discharges

    Page(s): 260 - 264
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    In this paper, a simple general electrical discharges circuit model for electrical discharge current waveform simulation in overvoltaged air gaps is presented. A macroscopic circuital method of simulation utilizing the standard SPICE network simulator, based on a two-dimensional (2-D) nonlinear impedances network has been proposed. The structure of the simulation framework is designed to take into account the electrode geometries in a straightforward way. A study of conducted current waveform for different electrode geometries has been done. Experimental data have been used to validate the simulation results View full abstract»

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  • On calculation of the ground transient resistance of overhead lines

    Page(s): 193 - 195
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    A constraint on the calculation of the ground transient resistance of overhead lines for small values of time is pointed out. The method for overcoming this constraint is proposed. The source of the ground transient resistance singularity is the low-frequency approximation of the ground impedance. It is shown that the ground transient resistance is not singular for t→0 if it is calculated without the low-frequency approximation View full abstract»

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  • Anechoic chamber evaluation using the matrix pencil method

    Page(s): 169 - 174
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    A new method for evaluation of an anechoic chamber using the matrix pencil method is presented. A signal measured between two antennas placed in an anechoic chamber is sliced into small frequency intervals and is processed using the matrix pencil method. In each interval, the measured signal is decomposed into its propagating-wave components, which correspond to a direct propagation between two antennas and reflected propagating waves from absorbing walls. The ratio of amplitudes of the reflected wave components with respect to the direct path propagation gives a new measure of quality factor for an anechoic chamber View full abstract»

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  • High electric conduction property of composite copper-clad steel wire

    Page(s): 196 - 201
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    The authors of this paper discover the high electric conduction property of the composite copper-clad steel wire; that is to say, in a specific frequency domain, its electric conduction property is higher than that of copper wire having the same diameter. This paper describes the relationship between this high conduction property as a function of the frequency and structure of the wire and points out that the property results from the reflection of an electromagnetic (EM) wave at the interface inside the composite wire 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.

Full Aims & Scope

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