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Electromagnetic Compatibility, IEEE Transactions on

Issue 1 • Date Feb 2001

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Displaying Results 1 - 13 of 13
  • Radio frequency coupling between an antenna and two unshielded parallel wires above a metal sheet-measurement precautions

    Page(s): 85 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    An unshielded 1 m transmission line, made of two parallel wires suspended 0.1 m above a plane metal sheet, is illuminated in the VHF and UHF bands by a log-periodic dipole array (LPDA). A network analyzer is used to measure the voltage induced at one end of the line. The measured signal is compared to the predictions of a moment method numerical analysis, using the NEC code. The measured and predicted coupling are in reasonable agreement only once two measurement precautions are taken. First, the illuminating antenna has to be well-balanced to suppress common mode radiation from the coaxial cable connecting the transmitter to the antenna. Second, an output balun must be inserted between the unshielded transmission line and the coaxial cable to the network analyzer. This is needed to prevent common mode signals on the coaxial cable from contaminating the measurements. Besides these practical steps, it is also necessary to use physical insight and high frequency circuit theory to develop a good equivalent circuit of the output balun for use in the computational model View full abstract»

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  • Large current radiator with S-diode switch

    Page(s): 94 - 100
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A large-current radiator (LCR) for the radiation of nonsinusoidal electromagnetic (EM) pulses with duration in the nanosecond range was developed. The time variation of the radiated electric field strength resembles one period of a sinusoid with the peak amplitude of the first half cycle being 1.2 times as large as the peak amplitude of the second half cycle. The duration of the first half cycle measured at one half the peak amplitude is 1 ns while the duration of the whole signal is 3.5 ns. The peak amplitude of the electric field strength at a distance of 3 m from the radiator is 56 V/m View full abstract»

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  • Statistical EM field models in an externally illuminated, overmoded cavity

    Page(s): 56 - 66
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    A description is given of the statistics of EM fields and power fluxes inside a highly overmoded, leaky, externally driven cavity. We explore various modeling combinations of chi square (with two and six degrees of freedom), normal, and log normal distributions. Convolution (in an unusual, logarithmic sense) of the two chi square models (with two and six degrees of freedom) proves to provide the best match with observation. Statistically generated field models are then used as drivers of cable codes describing the wiring in an aircraft shell. Modeled cable-current cumulative distribution functions match experimental results within a factor of two, which is commensurate with the configuration and measurement uncertainty View full abstract»

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  • A study on stray capacitance modeling of inductors by using the finite element method

    Page(s): 88 - 93
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Stray capacitance modeling of an inductor is essential for its RF equivalent circuit modeling and inductor design. Stray capacitance determines an inductor's performance and upper frequency limit. A method has been proposed for modeling the distributed stray capacitance of inductors by the finite element method and a node-to-node lumped capacitance network. The effects of wire insulation layer, ferrite core, number of segments used to model the circumference of a wire cross section, pitch and coil-to-core distances, and the capacitance between nonadjacent turns, etc., an an inductors' self-capacitance and calculation accuracy, have all been considered. The calculated equivalent lumped stray capacitance for a rod inductor with a ferrite core is compared to that estimated from measurement. Good agreement between them has been observed View full abstract»

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  • FDTD and experimental investigation of EMI from stacked-card PCB configurations

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    Stacked-card and modules-on-backplane printed circuit-board geometries are advantageous for conserving real-estate in many designs. Unfortunately, at high frequencies, electromagnetic magnetic interference (EMI) resulting from the nonnegligible impedance of the signal return at the connector may occur. This effective EMI coupling path results in the daughtercard being driven against the motherboard and attached cables, resulting in common-mode radiation. The connector geometry can be modified to minimize the EMI coupling path when high frequencies are routed between the motherboard and daughtercard. Current speeds and printed circuit board (PCB) sizes result in geometries that are of significant dimensions in terms of a wavelength at the upper frequency end of the signal spectrum. The PCB geometries are then of sufficient electrical extent to be effective EMI antennas. The resonant lengths of the EMI antennas may, however, be quite removed from the typical half-wavelength dipole resonances. The finite difference time-domain method can be used to numerically analyze the printed circuit board geometries, determine antenna resonances, and investigate EMI coupling paths. EMI resulting from the stacked-card configuration has been investigated experimentally and numerically to ascertain the EMI coupling path at the bus connector, and EMI antennas View full abstract»

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  • Damping resonances within a screened enclosure

    Page(s): 45 - 55
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    This paper describes the development of partial lining techniques for damping resonances in screened rooms. The theory behind the techniques is discussed and results of measurements are presented. The results of modeling partially lined enclosures are also presented. The results show that it is possible to predict the effect of lining a screened enclosure with different quantities of ferrite tiles and hence to design low-cost, precompliance test environments using partial lining techniques View full abstract»

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  • Electrical fast-transient test: conducted and radiated disturbance determination by a complete source modeling

    Page(s): 37 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    Tests against electrical fast transient/burst (EFT) represent a serious threat for modern high-speed electronics: besides the conducted injection of high amplitude pulse, a strong radiated field is produced during this test. The prediction of the effects of this test during the equipment early design stage requires the equivalent circuit of the generator: the output waveform into a resistive 50-Ω load is not sufficient to recover the complete circuit, including inductive component and parasitic elements. These are essential to predict the disturbance produced in arbitrary loads, as the equipment under test can be viewed. This paper describes how to characterize the EFT generator by means of the measurement of the output voltage and current produced in presence of known loads; moreover, a procedure to calculate the current on the equipment power cord is shown, based on the use of a circuit simulator (PSPICE). Finally, the disturbance produced on different loads and the radiated field during the test are calculated and experimentally validated View full abstract»

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  • Calibration of current transducers at high frequencies

    Page(s): 100 - 104
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    The transfer impedances of current transducers are estimated using a special calibration fixture, which is often assumed to be perfectly matched at its coaxial ports. However, the errors inherent in this approximation increase with frequency, making the measurement of cable currents increasingly inaccurate at higher frequencies. A one-dimensional (1-D) transmission line model is proposed to account for such errors in a calibration fixture of simple design by using additional measurements to quantify the mismatches in the system. This technique is validated using a numerical model of such a calibration fixture as well against experimental data and numerical predictions for the current induced on a wire inside a rectangular cavity due to an external source that is coupled into the interior via an aperture. It is concluded that the proposed approach provides improved results with a calibration fixture of simple design for frequencies up to at least 600 MHz View full abstract»

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  • A mixed model for the determination of normalized site attenuation in OATS

    Page(s): 29 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    Normalized site attenuation (NSA) has become the standard method for determining the adequacy of open area test sites (OATS) to perform electromagnetic interference (EMI) emission and immunity measurements. Practical experience and measurement data have shown to great extent that in cases where the hypothesis of an infinitely conducting ground plane cannot be fulfilled, the models, up to the present, are not exact. The objective of this paper is to obtain a simple but more accurate model for the measurements of several equipment under test (EUT). The model introduced is based on complex image theory, and also accounts for the near field correction factor and the contribution of Norton surface wave component (vertical electric dipoles cases, only) in a simple algebraic model. Four well-known models are compared to the one presently introduced leading to some useful results, such as the accuracy of the proposed model View full abstract»

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  • Underground electromagnetic fields generated by the return strokes of lightning flashes

    Page(s): 75 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    In this paper, equations are developed in the time domain to represent lightning generated electromagnetic (EM) fields at different depths below the ground surface. The equations connect underground EM fields to surface fields that can easily be measured or calculated. Numerous examples are given to illustrate how the signature of the electric and magnetic field vary as a function of depth as well as conductivity View full abstract»

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  • Approximate calculation methods for pulse radiation of a TEM-horn array

    Page(s): 67 - 74
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    Simple approximate calculation methods of pulse radiation by a TEM-horn array are suggested. The first one is based on substitution of the radiation field of each horn to a system of V-antennas; the currents in all of these are equivalent to a single horn current distribution. The second one is based on Huygens-Kirchhoff method applied for time domain. The experimental investigation of radiation field by the array and comparison with results calculated have been carried out View full abstract»

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  • Transfer impedance of nonmagnetic conduits of various shapes

    Page(s): 18 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Metallic conduits provide mechanical support for cables, and may also protect the cables against interference caused by currents induced by external electromagnetic fields. The conduit transfer impedance Zt then is a good measure for the provided protection. We studied Zt by means of conformal transformations and of the method of moments in a quasistatic, two-dimensional (2-D) approach. Practical U-, H-, L-, and T-shaped conduits are discussed. Conformal transformations provide simple engineering expressions for the mutual inductance part of Zt for cable positions inside the conduit. The method of moments formulation results in useful approximations for the crossover frequencies in Zt between DC and high frequency. Measurements on U-shaped conduits confirm the calculations View full abstract»

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  • Fast transmission line coupling calculation using a convolution technique

    Page(s): 11 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    A fast method for the calculation of the mutual coupling between transmission lines is presented. The method is based on using the convolution of the incident field and the current induced by a Dirac impulse type field. Only first-order coupling between the lines is taken into account. This means that only the current induced by the source line is taken into account and all currents resulting from induction by this induced current are discarded. The technique is orders of magnitude faster than traditional moment method techniques because no large matrix equations need to be solved 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