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Electromagnetic Compatibility, 1988. Symposium Record., IEEE 1988 International Symposium on

Date 2-4 Aug. 1988

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Displaying Results 1 - 25 of 92
  • IEEE 1988 International Symposium on Electromagnetic Compatibility. Symposium Record (Cat. No.88CH2623-7)

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  • Power reflection techniques in susceptibility tests of electronic devices

    Page(s): 1 - 5
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    A setup for statistical tests of electronic devices with fast transients is described. It contains a transient generator, the test box for the device-under-test (DUT), and a delay line along with a digitizing oscilloscope and personal computer. The purpose is to find a relationship between the damage threshold and time-dependent functions of the voltage, current, and power and the total energy absorbed in the DUT. The outgoing pulse of the generator is compared with the pulse reflected by the electronic device. An evaluation method based on time-domain reflectometry (TDR) and the Fourier transform is developed, taking into account experimental uncertainties. The minimum requirements for the digitizing scope are a sample frequency of at least 500 MHz and sufficient storage depth. The results are compared to measurements with known impedances of the DUT (Resistors, short circuit and open end) for voltages below 2 kV; the differences are below 5%, which is tolerable in comparison to the maximum measuring error of the digitizing scope (typically 5%).<> View full abstract»

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  • Analysis of electromagnetic fields in loaded TEM cells by finite element method

    Page(s): 6 - 8
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    The distribution of the electromagnetic field in a transverse-electromagnetic-field (TEM) cell, loaded with various equipment-under-test (EUT), is calculated using the finite-element method (FEM). The calculations are performed for a two-dimensional (2-D) configuration for inhomogeneous dielectric-conductor EUTs of various cross-sectional dimensions. The set of curves obtained provides a means of estimating the uncertainty of the TEM cell measurements and can be used as a quick reference guideline for predicting the maximum dimensions of the EUT for a given field distortion.<> View full abstract»

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  • Diagnosis and reduction of conducted noise emissions

    Page(s): 19 - 23
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    A systematic method for the diagnosis and reduction of conducted noise emissions is described. A device for determining whether the differential- or the common-mode component of conducted noise is dominant is described. This information is used to determine which element of the filter should be changed to effect a reduction in the total emission. The use of the method to modify a power-supply filter is described.<> View full abstract»

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  • EMI response of cable systems to transients considering complex transfer impedance

    Page(s): 24 - 29
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    An improved theoretical approach for calculating the voltage response excited at the terminations of a shielded cable system by an ambient signal is presented. No restrictions are placed on either the current distribution or the local transfer impedance (Z/sub T/). The method is applicable to arbitrarily oriented cable-system structures. Experimental results show good agreement with theoretical predictions for the example considered. Some recommendations applicable to future shielded-cable test standards are included.<> View full abstract»

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  • Mode-stirred chamber for measuring shielding effectiveness of cables and connectors: an assessment of MIL-STD-1344A method 3008

    Page(s): 30 - 36
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    The mode-stirred method for measuring the shielding effectiveness (SE) of cables and connectors as specified in MIL-STD-1344A method 3008 is examined. Problems encountered in applying the method are identified, and recommendations to obtain improved results are provided. These include chamber design, type and placement of transmitting and reference-receiving antenna, determination and correction of the voltage standing-wave ratio (VSWR) of the reference antenna and equipment-under-test (EUT), and the measurement approach to use at specified test frequencies. Design and measurement setups for a small mode-stirred chamber suitable for performing SE measurements in the 1-18-GHz frequency range with dynamic ranges up to 130 dB are given along with SE measurement results of some sample EUTs.<> View full abstract»

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  • EMP coupling to coaxial shielded cables

    Page(s): 37 - 44
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    A method for determining the effects induced within shielded cables by a high-altitude nuclear electromagnetic pulse (EMP), represented as a plane wave, is presented. The cable is regarded as a multiconductor line in which the EMP sources are impressed on the shield. An efficient matrix procedure permits simultaneous calculation of transient voltages and currents at any point on each conductor. This procedure, which is based on transmission-line theory, involves modal propagation and reflection matrix operators. The method of analysis permits fast calculation of voltage and current in the shield and inner conductor, whatever the terminal impedance may be. Comparison of the results obtained by applying the single and multiconductor approaches reveals a few significant differences in the case of the braided-shield cables which become more important as lengths increase, as well as in given closing conditions.<> View full abstract»

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  • SHF/EHF field-to-wire coupling model

    Page(s): 50 - 54
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    Method-of-moments calculations have provided a database for deriving an empirical algorithm to characterize SHF/EHF coupling. The data show that the maximum field-to-wire current coupled into a port saturates as a function of height above the ground plane and that the saturation level can be simply characterized. The most important parameter in determining the saturation current is the near-port termination impedance. A computationally efficient algorithm is derived and can be incorporated into electromagnetic-compatibility (EMC) surveying/culling tools such as the IEMCAP code. The algorithm has been verified by coupled current measurements in an anechoic chamber. Cable-grounding conditions, port-termination resistance, and cable transmission loss are treated as input parameters in the algorithm.<> View full abstract»

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  • The evolution of MININEC (method of moments computer program for antenna analysis)

    Page(s): 66 - 68
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    The Mini Electromagnetics Code, or MININEC, is a method-of-moments computer program for the analysis of thin-wire antennas. A Galerkin procedure is applied to an electric-field integral equation to solve for the wire currents. This formulation results in an unusually short computer program suitable for implementation on a microcomputer. Hence, MININEC is written in BASIC, which is compatible with many popular microcomputers. MININEC capabilities include determination of impedance and currents, calculation of near and far fields, and calculation of radiation patterns. The solution includes all electromagnetic interactions between conductors, so the code can be used to determine antenna-to-antenna coupling, a necessary requirement for the electromagnetic compatibility (EMC) assessment of a cosite antenna environment. The development of MININEC from its conception is described. The capabilities are described and illustrated with examples. Future developments are included.<> View full abstract»

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  • Finite element method applied to shielding performance of enclosures

    Page(s): 69 - 72
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    The shielding effectiveness of enclosures is predicted by means of a computer simulation based on the finite-element technique. To characterize shielding performance, possible sources of electromagnetic interference (EMI), such as radiated EMI, conducted EMI, grounding, electrostatic discharge and environmental effects, along with their corresponding distances (near- or far-field) to the equipment under test (EUT), are examined. The analysis considers only the penetration of the magnetic field through the walls and apertures, since the electric field attenuation is high when a good conducting material is used for the shield. A finite-element method that is based on a magnetic vector-potential formulation is used; it can be applied to calculate the shielding effectiveness of any arbitrary selected enclosure. The ultimate purpose of this CAD tool is to establish guidelines regarding aperture spacing on the enclosure and to identify regions of high field intensity that must be avoided by designers when locating sensitive circuits.<> View full abstract»

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  • Design of broadband antenna matching networks

    Page(s): 78 - 81
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    The theoretical limitations of the design of antenna-matching networks that provide a constant voltage standing-wave ratio (VSWR) are discussed. The development of a numerical method to design these networks as well as its implementation in a very user-friendly computer program is described. Several examples of the computer program use are presented, and the application to broadband EMC measurements is discussed.<> View full abstract»

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  • Improvement in antenna factor measurements using time-domain gating

    Page(s): 82 - 86
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    A method for improving site attenuation and antenna-factor measurements using time-domain gating is presented. Results of measurements for biconical antennas in the 20-200 MHz range for both polarizations, using various time gates are presented. It is shown that a judicious choice of time gates results in a tremendous improvement in the accuracy of site attenuation and antenna-factor measurements especially for the vertical polarization.<> View full abstract»

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  • Structure of EM field at an open field site

    Page(s): 94 - 98
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    Detailed field plots showing the structure of the measured electromagnetic (EM) field in a three-dimensional volume of an open-field site, due to a variety of source antennas, are presented. Measured antennas include broadband antennas, such as the biconical and log-periodic antennas, as well as dipole antennas in the 50-MHz to 1-GHz frequency range. The results are in the form of contour maps of the amplitude and phase of the EM field in three cross-sectional planes containing the central axis of the antenna in a typical 3-m site configuration. Both horizontally and vertically polarized antenna orientations are studied.<> View full abstract»

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  • An investigation into the scattering and radiation characteristic of RF-absorbers

    Page(s): 99 - 105
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    The attenuation and radiation characteristics of a pyramidal absorber are studied, both analytically and experimentally, including bulk-parameter data for commercially available, measured samples. Absorber attenuation is modeled as a plane wave incident on a layered medium with a varying complex permittivity. Attenuation experiments performed in a TEM cell confirm the validity of this approach. The antenna behavior of the pyramidal absorber is also considered, treating it as a monopole antenna. The input impedance and radiation are both modeled and measured. It is shown that the absorber can radiate significantly, which can affect its usefulness, depending on the intended application. Special consideration has been given to the low-frequency performance (<100 MHz) of absorbers.<> View full abstract»

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  • Numerical investigations on pulse coupling to single and multiple conductor systems

    Page(s): 112 - 117
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    Pulse coupling to single- and multiple-conductor systems is investigated by means of numerical field calculations for excitation by a plane electromagnetic pulse field. The effects on a single wire are calculated first, and the difference between a short-circuit and open-circuit line is illustrated. For two systems of parallel lines of different lengths, some typical coupling effects are shown and interpreted. The resonances occurring in the frequency domain clearly form the shape of currents or fields in the time domain. A typical frequency-dependent current curve is compared with measured values.<> View full abstract»

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  • Multiconductor cable response dependency on propagation modes

    Page(s): 118 - 123
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    A theoretical and experimental study of the response of shielded multiconductor cables to external transient fields is presented. A relationship between propagation modes and peak voltage response of the conductors is established. Experimental observation of the propagation modes on a multiconductor cable proved difficult with traditional transform techniques. Therefore, a maximum entropy spectral estimator was used to identify the propagation modes. The experimental response of the multiconductor cable showed variations in the peak open-circuit voltage. Analysis of the data with a maximum-entropy spectral estimator indicated the presence of multiple propagation modes on the conductors. Due to the complex weighting of these modes by the impedance matrix, a direct relationship between the propagation modes and the peak voltage was not established, but in general the wires with larger propagation modes had higher voltage peaks.<> View full abstract»

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  • Radiation from a transmission line carrying current of an arbitrary waveform

    Page(s): 124 - 129
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    The radiation from a finite-length transmission line in which a current of arbitrary waveform is flowing is examined. This phenomenon can be considered to be the opposite of the coupling of a wave of an arbitrary waveform to the line. By representing both phenomena in the form of a three-pair-terminal network, the radiation problem can be examined using the circuit concept. An expression for the radiated electric field is obtained in terms of analytical functions. These functions suggest a radiation mechanism. Elements of the matrix describing the network in the Laplace domain can be determined from the coupling result.<> View full abstract»

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  • Susceptibility of cables in shielded environment to external excitations

    Page(s): 130 - 133
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    An approach to the analysis of cables in a shielded environment is presented. Electromagnetic sources exterior to this environment excite at least one of the cables. The formulation of this problem uses Fourier series to approximate the waveform of the unknown currents excited on each cable. The Fourier coefficients are determined by enforcing an appropriate boundary condition. The coupling among the cables in the shielded environment is taken into account; wire-to-wire impedance elements describe such coupling. Cables of arbitrary finite diameters can be easily treated. Results for various problems are given in the form of current distributions. Other parameters of interest can be easily obtained once the current distribution on each cable in the set is known. It is shown that physically reasonable solutions can be obtained for a variety of problems involving cables in the shielded environment.<> View full abstract»

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  • A new approach to electromagnetic coupling

    Page(s): 140 - 144
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    A method used to calculate the spatial distribution of currents within conducting structures of complicated shapes, as well as the near and far electric and magnetic fields around them, is presented. The structure is divided into segments that are modeled as prolate spheroids. A solution that is analytical and has a predictable behavior, yet can be easily implemented in computer code, is found for a single segment. Several segments are combined in manner similar to the method of moments.<> View full abstract»

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  • Frequency assignment for land mobiles in large urban areas

    Page(s): 145 - 150
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    Using the frequency assignment model of M.C. Delfour and G.A. DeCouvreur (see IEEE Trans. on Electromagn. Compatibility 1987), recent developments which further increases the capacity of the underlying assignment grid, incorporate a predetermined distribution of single-user and multiuser frequencies, and handle gaps in the band are presented. The method is applied to the present user distribution for the VHF land mobile from 138 to 174 MHz band in Montreal. The capacity increased from 25 channels/km/sup 2/ to 30 channels/km/sup 2/, i.e. an increase of about 58%. It is conjectured that a larger spectrum would yield even higher density. It is now possible to take into account gaps in a given frequency band. The analysis shows that they do not significantly affect the spectrum assignment process. Careful design also provides some control of the effect of gaps. Special techniques have been developed to produce a model that provides 50% of the spectrum for single-user and 50% for multiusers channels.<> View full abstract»

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  • Decongesting Navy non-tactical VHF band usage

    Page(s): 151 - 157
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    To alleviate worsening electromagnetic interference (EMI) due to congestion in the 138-150.8 MHz band, in 1982 the US Navy launched an engineering effort to realign systematically its Navy and USMC users in major geographic areas where it operates. The band is allocated to fixed, mobile, and radio navigation satellite services, but the military services use the band primarily for nontactical mobile communication. This effort is described in detail, including its goals, network architecture, realignment criteria, electromagnetic radiation patterns, network grouping, and realignment planning.<> View full abstract»

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  • An effective frequency assignment technique for solving problems subject to multiple constraints

    Page(s): 158 - 163
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    A technique that has been used for solving large-scale frequency assignment problems involving multiple constraints is described. The model has a modular construction that enables it to be adapted to a variety of assignment problems. The major contribution is an effective procedure for exploiting all of the assignment constraints to define a sequence in which the assignment requests should be processed. A number of examples are presented that illustrate how the techniques can be used to achieve the assignment objectives.<> View full abstract»

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  • Fields radiated by electrostatic discharges

    Page(s): 179 - 183
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    The problem of electrostatic discharge (ESD) radiated fields problem is examined, both theoretically and experimentally. Measurements indicate that the electric fields can be quite significant (>150 V/m at a distance of 1.5 m), particularly for relatively low-voltage sparks (<6 kV). A theoretical dipole model for the ESD spark is developed to compute the radiated fields. The agreement between theory and experiment is good. The model can be used to predict the fields for a wide range of possible discharge configurations.<> View full abstract»

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  • Test procedure and specifications for component susceptibility to electrostatic discharges

    Page(s): 190 - 195
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    A component-level electrostatic discharge (ESD) test procedure and specifications, developed to provide a means for early evaluation of ESD compatibility of electronic systems, is presented. The steps taken in the development of the ESD component procedure and specifications are reviewed. Three discharge methods and the variables associated with them are discussed. Conclusions are presented based on experimental findings. The required criteria for the evaluation of commercial ESD simulators are discussed.<> View full abstract»

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  • Standardization of electrostatic discharge testing

    Page(s): 196 - 199
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    An overview is given of the activities and directions of the various worldwide committees working on the electrostatic discharge (ESD) phenomena. The current technical issues, position, and documentation status are discussed for each committee. The technical aspects of the work done to date, as well as its resolution or discrepancies, are presented.<> View full abstract»

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