Showing papers on "Electromagnetic compatibility published in 1983"

Measurement and Analysis of Radiated Electromagnetic Emissions from Rail-Transit Vehicles

Abstract: Various operational considerations have led intro-introduction of solid-state dc propulsion control systems, to replace the older cam controllers in rapid-transit propulsion systems. The simultaneous introduction of audio-frequency signaling and train control systems using jointless rails has made it necessary to coordinate the design of these two new technologies in order to achieve intrasystem electromagnetic compatibility (EMC). At present, the conductive and inductive interference mechanisms are fairly well understood and this paper deals primarily with radiated electromagnetic interference (EMI) effects. Radiated emissions could potentially interfere with local radio-communications services or sensitive electronic equipment in the area. Measurement programs were conducted at various locations in the U.S. between 1979 and 1981. Magnetic (H) Field and Electric (E) Field measurements were performed over the frequency range 20 Hz to 1 GHz. Information from these measurement programs will provide a data base for eventual use in the preparation of recommended test procedures and emission limits for rail-transit systems. The use of a spectrum-analyzer system for the measurements of E-and H-Field levels emanating from a moving rail vehicle has many advantages. It was found that H-Field levels above 30 MHz decrease rapidly with distance and E-Field levels below 10 kHz were negligible.

Low-reflection, shielded, metallic simulation chamber for electromagnetic radiation

Abstract: Due to multiple reflections, an inhomogeneous distribution of field strengths occurs in simulation chambers for examining the electromagnetic compatibility (EMC) or electromagnetic pulses (EMP). To smooth out this distribution, it is proposed to terminate the chamber in the audio-frequency range by means of a number of parallel-connected low-inductance high-voltage resistors (Z) in a balanced arrangement. For the radio-frequency range, the rear wall can be covered with ferrite absorbers (F) (Fig. 1). The high-voltage resistors (Z) are preferably mounted along lines of equal potential.

RF Conducted noise measurements of automotive electrical and electronic devices using artificial network

Abstract: Two RF conducted noise measurement systems have been developed for laboratory measurements of automotive electrical and electronic devices. One is a noise emission measurement system for measuring noise level from the electrical devices while the other is a susceptibility measurement system for measuring the susceptibility level of the electronic devices to the noise. The former's function is to measure a histogram of noise level, and the latter functions both to measure the malfunction level and to judge a malfunction mode of the electronic devices. These measurement systems are applicable to the frequency of 150 kHz-60 MHz. These are for laboratory measurements performed with the measurement systems connected to an artificial network of the automotive electrical network. This artificial network represents electrical networks used on Japanese compact passenger vehicles.

Electromagnetic noise from an ion engine system

Abstract: The conducted and radiated emission of electromagnetic noise from an ion engine system was measured. The measured data were compared with MIL-STD-461A and a specification for the ion engine system on ETS-III, and found to satisfy the latter specification. During the conducted emission measurements, three discharge modes were observed and their oscillating characteristics were compared. An ion acoustic wave was generated spontaneously during a low discharge voltage mode. A relatively narrow discharge voltage range was found to minimize the noise.

Single Design Approach to Commercial EMC Step-1

Abstract: SYSTEM GROUNDING This paper presents Step-1 in a Single Design Approach to Commercial EMC that allows a product to meet the FCC/VDE emission specifications and meet the susceptibility criteria to survive in the polluted electromagnetic environment that exists today.

A Program for Experimental Verification of Electromagnetic Compatibility Analtsis Models

Abstract: This paper describes the technical methodology, planning and accomplishment of a test program to: 1) experimentally determine the validity and accuracy of currently used Electromagnetic Compatibility (EMC) radiated emissions and susceptibility analysis models; 2) develop an analytic model, if required, for incorporation into standard analysis procedures to describe the resonance and reflection effects of the EMC test environment in a shielded enclosure; and 3) provide a data base for further analysis model development.

Increasing Significance of Electromagnetic Effects in Modern Aircraft Development

Abstract: : Due to the use of new materials, the enlargement of the electromagnetic environment, the increasing susceptibility of electronic components and the arising dependence on satisfactorily functioning electronics, greater attention must be paid to electromagnetic effects in modern aircraft development. The increase in the scope of problems in comparison with the past and the possibilities which can be recommended for their solution are presented in this paper. (Author)

Defining and Measuring EMC Performance of Electronic Cables

Abstract: An electronic cable EMC performance parameter is introduced and defined as a measure of cable input to the undesirable emissions and interference susceptibility o f electronic system. The specific features of cable EMC performance are discussed and evaluation methods described. The results o f such evaluation are presented and related to the shielding effectiveness o f popular electronic cable and power supply cord types. INTRODUCING EMC PERFORMANCE AS A BASIC ELECTRONIC CABLE PARAMETER An electronic cable is one of the main sources, as well as victim, of electromagnetic interference. Being an integral part of electronic devices and computer and communication networks, it affects their compatibility with other equipment and susceptibility to natural elec­ tromagnetic phenomena (see Figure 1). Hence a general concept of the electronic cable, as well as other components, EM C performance can be defined as a measure of their input to the undesirable emis­ sions and susceptibility of the system incorporating these components. Such definition is valid for any component of any electronic system. Electronic cable EMC performance, as defined, is a system parameter. It depends not only on the cable design and characteristics, but also on the cable interaction with other system elements: connec­ tors, terminal equipment, other cables. It also depends on the line working mode, signal parameters, environment properties and groun­ ding techniques. It is expedient, therefore, to determine the EMC per­ formance of the cable under the same terms and in the same units as for the whole system. Thus, in accordance with standards and prac­ tices, two basic approaches are possible: "antenna” approach, and "crosstalk" approach. The “ antenna” approach leads to a “one-end” solution. It is bas­ ed on the determination of either the cable radiating field, or its im­ munity factor (susceptibility), with all other system elements being taken into account. In the first case, the cable EMC performance can be measured in electromagnetic power or field intensity units, at some specified distance fromand length of the cable, and related to a reference signal, introduced into the cable circuits. In the second case, the power (or voltage, or current) is determined in the cable and related to the ambient field intensity, again under specified conditions. The “ antenna” approach is most useful, when the presence of receptor produces a negligible reaction on the source, so that the mutual ar­ rangement of the interference source and receptor can be easily ac­ counted for, and/or when one of them is not specified. Far field zone applications meet these conditions, as often do the electrostatic and magnetostatic interference regimes. There are also situations when electromagnetic compatibility is largely dependent on the source physical properties and mutual ar­ rangement of the source and receptor, so that they cannot be separated without major changes in the whole system EMC perfor­ mance. This is more inherent to the near field zone. One of the typical examples is crosstalk between the cables or circuits in the same cable. In such situatTons the “crosstalk” approach appears more expedient. It is based on the determination of the difference between the signal in the emitter and interference in the receptor. This can be the voltage transfer ratio, insertion losses, etc. in a more general sense, crosstalk can be considered between the electronic cable and any other equip­ ment, or even between “ non-cable” components. Obviously, the most accurate results are obtained when the test con­ ditions are identical to the real electronic system of which the tested cable is a part. Most often, however, the practical evaluation will be necessarily limited to the most important parts of the system, or their approximate models, and some standardized test arrangement. The trade-offs involve accuracy vs. cost, time and iabor consumption, while the practical EMC performance evaluation can range from just a piece of cable with proper terminations, and up to the real system itself, depending on the test goals and limitations. EMC requirements are stimulating the use of shielded electronic cables. It is important therefore to relate the cable’s EMC performance to its shield effectiveness. The problem Is, though, that there is no sole, generally accepted definition of shielding effectiveness. Due to complexity and diversity of cable-related EMI, the study of coupling mechanisms, shield working modes, and evaluation methods historically developed in several separate ways, as illustrated on Figure 2. E M I AND S H I E L D I N S P A R A M E T E R C L A S S I F I C A T I O N F O R E L E C T R O N I C S C A S L E S PARAMETER CHARACTERISTICS

Random Susceptibility of an IC 7400 TTL Nand Gate

Abstract: A p r o b a b i l i s t i c e l e c t r o m a g n e t i c co m p a t i ­ b i l i t y (EMC) model i s proposed f o r m i c r o c i r ­ c u i t s . This paper d i s c u s s e s t h e randomness observed when th e s u s c e p t i b i l i t y l e v e l s of more tha n two hundred " i d e n t i c a l " i n t e g r a t e d c i r c u i t 7400 TTL NAND g a t e s were de te rmined e x p e r i m e n t a l l y .

Effect of Degraded Absorber Performance on EMC Measurements

Abstract: Use of absorber lined chambers (ALC's) for measurement of EM emission and susceptibility is based on the assumption that field degradation is not significant enough to be detrimental to such measurements. In order to evaluate the validity of this assumption, computed fields inside various ALC configurations are compared to corresponding fields in "open-field” and "free-space" sites. The results presented show such comparisons for different room shapes and sizes, lining material characteristics (reflectivity), source types and site distances over a wide frequency range. Suitability and some considerations in the design of low cost ALC's for wide frequency range EMC measurements are discussed. SUMMARY INTRODUCTION Absorber lined chambers have been the subject of extensive study recently as they provide an excellent means of bridging the "gap" between the inherent upper frequency range of operation of low frequency "known field" simulation and practical low frequency limit of high frequency "open field" simulation techniques (1,2,3). Detailed measured data for fields inside ALC's (4) and design procedures based on measured data (5) and experience (6,7) are also available. A computational technique to approximately predict the field distribution has been developed and used (8,9) for the design of ALC's. The question of accuracies of EMC (Electromagnetic Compatibility encompassing emission and susceptibility) data obtained by measurements inside such chambers, however, has not been fully answered. Available information consists of only some measurement and comparison of "site attenuation" in ALC's and "open field" sites (10). Also some data showing improvement in field uniformity by treating the walls of shielded enclosures by absorber material fully (11), or in selected locations (12) have been reported. This paper presents the results of a computational study carried out with the objective of estimating measurement accuracy or "errors" that may be expected because of degraded absorber performance. COMPUTATIONAL TECHNIQUE Computational technique uses geometrical optics (GO). The reflectivity of the absorber material is modelled as a linear function of frequency (18.5 dB/decade slope) (13). Dependence of absorber reflectivity on angle of incidence is approximated empirically by a cosine function (8). Computations are carried out for a variety of ALC configurations involving a rectangular cube shaped ALC with different height H, width W and length L ratios over a wide range of frequencies and for different lining conditions. Many types of illuminating sources in different locations within the chambers are considered. The computed results include: 1. For a fixed ALC shape and size, i. Transmission frequency. loss as a function of ii. Transmission distance from loss the as a source. function of iii. Transmission loss as a function of absorber thickness (reflectivity of the material), 2. Effect of changing the shape (H:W:L ratios) and size of the ALC on transmission loss. 3. A comparison of fields in ALC's to the corresponding fields in "free space" and "open field" sites for different conditions indicated above in 1 and 2. 4. Effect of using different sources such as 1) a point source, and 2) tuned dipoles (both horizontally and vertically polar­ ized. CH1838-2/83/0000-0498 $1.00 © 1983 CCC 4 9 8 OUTLIN E OF T H E ALC M O D E L

The electromagnetic environment for the Space Shuttle orbiter

Abstract: The electromagnetic environment of the Shuttle orbiter is discussed with respect to the electromagnetic compatibility of the orbiter and its cargo. Effects on payloads of the orbiter's Ku-band antenna are considered, along with the effects of unintentional emissions in the cargo bay, the magnetic fields produced by the orbiter and various payloads, lightning-produced magnetic fields, and noise and transients in the AC and DC power buses. Special EMI testing is described that was carried out to substantiate the orbiter's electromagnetic compatibility. It is concluded that the orbiter presents a very benign electromagnetic environment for cargo except for payloads or experiments that use very sensitive receivers or instruments that can measure low magnetic or electric fields.

A Computing Model and Its Experimental Testing for an Evaluation of Electromagnetic Interferences Created by Interfering Circuits on Transmission or High-Voltage Lines Above a Dissipative Ground

Abstract: In this paper we present useful calculations for a prediction of the electromagnetic field created by interfering circuits on a linear horizontal transmission line over an imperfectly conducting ground.

A Comparison of IEMCAP and SEMCAP

Abstract: A comparison is made of IEMCAP and SEMCAP, two Electromagnetic Compatibility Computer programs that are capable of analyzing the interaction of a large system and evaluating its interference margins or adjusting the System requirements to achieve compatibility. In general the overviews have the following features and characteristics. 1. Computer Requirement 2. System size limits 3. Input/Output 4. Types of coupling paths The models used with the features of each are compared, along with those features which are included in one but not the other. The strengths and weaknesses are compared, and the general characteristics listed to assist in the selection of a code for a particular application.

The Design of an Automated, High-Accuracy Antenna Test Facility

Abstract: This paper presents the step-by-step application of proven far-field range and instrumentation design techniques to a specific antenna measurement problem, describes the resulting facility design, and presents the predicted measurement uncertainty. Fundamental electromagnetic design criteria for an outdoor, far-field facility establish minimum dimensional requirements for the range design and limiting values of source-antenna directivity. Electromagnetic compatibility of the facility is assured by frequency coordination with existing and planned services in the area surrounding the available site. Additional design constraints for this facility included restricted measurement time, reduction of spurious test enclosure effects, limited available terrain, and required data quality. In this case, the required range length is in excess of 6500 ft, and paraboloidal source antenna diameters up to 23 ft are required. The frequency coordination problem was solved by exploiting the natural terrain features and configuring the measurement system as "test-on-transmit." Signal and reference paths share the same range cable. The quantity of data that must be handled in the available measurement interval required the use of a computer-based measurement system.