EP0254964A2 - Magnetic or electromagnetic shield and electrical cable equipped with it - Google Patents
Magnetic or electromagnetic shield and electrical cable equipped with it Download PDFInfo
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- EP0254964A2 EP0254964A2 EP87110235A EP87110235A EP0254964A2 EP 0254964 A2 EP0254964 A2 EP 0254964A2 EP 87110235 A EP87110235 A EP 87110235A EP 87110235 A EP87110235 A EP 87110235A EP 0254964 A2 EP0254964 A2 EP 0254964A2
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- shielding
- layer
- magnetic
- doped
- plastic
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B11/00—Communication cables or conductors
- H01B11/02—Cables with twisted pairs or quads
- H01B11/06—Cables with twisted pairs or quads with means for reducing effects of electromagnetic or electrostatic disturbances, e.g. screens
- H01B11/10—Screens specially adapted for reducing interference from external sources
Definitions
- the invention relates to electromagnetic or magnetic shielding and electrical cables constructed therewith.
- cables For high frequency applications are cables, whose shielding consists of a simply braided shield, often not sufficient. A better shielding effect can be achieved with two braided shields. In the case of very high demands on the shielding effect, as is required, for example, in the field of space travel, aviation, telecommunications and data processing, such a shielding is also not sufficient.
- cables with three-layer shielding have been created, the inner layer and the outer layer each being formed by a metal braid shield and the intermediate layer by a polycrystalline material such as, for example, ⁇ -metal, metallic glass and the like.
- Such a shield structure leads to cables with only little flexibility and with difficult processing when connecting to the contact elements of plug connect.
- essentially only a shielding of electrical springs is achieved, but not magnetic fields.
- the electrically conductive intermediate layer electrically connects the inner shield and the outer shield, and therefore the three-layer shield basically acts only as a thick-layer shield.
- a coaxial cable which has a magnetic layer between two metal shields, which is a non-conductive or only slightly conductive magnetic mixture which by mixing in ferrite dust or other magnetic metallic dust a flexible plastic carrier material can be produced.
- doped insulating layers leads to improved cable flexibility compared to cables with rigid shielding layers.
- the shielding attenuation should be greater than 100 dB for the largest possible frequency range in order to prevent radiation and radiation of interfering signals in the largest possible frequency range.
- Electromagnetic radiation on the signal to be transmitted has a negative effect, particularly in the case of digital signals, in that the pulse edges are flattened, which leads to signal falsifications and a reduction in the possible pulse repetition frequency.
- An object of the invention is to make available electromagnetic shielding which, with a highly flexible cable structure, leads to a high shielding attenuation of both electrical and magnetic fields in the widest possible frequency range.
- the one layer of the shield consists of metal-doped plastic and highly flexible plastics are available, a cable provided with the shield according to the invention does not have to suffer any loss of flexibility.
- the extraordinarily good electromagnetic shielding damping properties are achieved in that the magnetic field emitting or emitting is bundled in the shielding layer from plastic doped with non-magnetic metal particles.
- Shields against electrical fields which consist of electrical conductors, act in that these electrical conductors form an equipotential surface which is connected to the potential 0 by external connection, for example.
- Charge carriers which are caused by local electrical fields, flow away immediately, which creates the electrical shielding effect. The higher the electrical conductivity, the better the electrical shielding effect.
- Such electrical conductors have no or only a very weak shielding against magnetic fields, if one disregards very high frequencies in the GHz range. In particular in relatively low frequency ranges, for example in the lower MHz or even KHz range, there is practically no magnetic shielding.
- non-magnetic metal particles such as copper powder
- induced eddy currents are produced in these metal particles by the high-frequency magnetic field, which in turn cause a magnetic field that is opposite to the external magnetic field.
- the eddy current strength and thus the magnetic shielding effect increases with increasing magnetic field strength and increasing frequency, which not only leads to higher shielding attenuation than with ferrite doping per se, but also extends the range of good shielding attenuation into much higher frequency regions.
- the measure according to the invention therefore leads to surprisingly good magnetic shielding results.
- a three-layer shield the inner and outer shield layers of which are each formed by an electrical conductor such as, in particular, a metal braid or a metal foil and whose middle layer is formed by the metal-doped plastic layer.
- the latter leads to electrical insulation between the inner ones and outer electrically conductive shield layer. This causes the electrical field to be shielded to be reflected on two electrically different shielding layers.
- the shielding according to the invention with an intermediate plastic layer, in which non-magnetic metal particles are embedded therefore leads to a considerably better magnetic shielding via a very wide frequency range, while maintaining good cable flexibility.
- a cable provided with the electromagnetic shielding according to the invention can therefore have both high flexibility and an outstanding electromagnetic shielding.
- the flexible, electrically non-conductive plastic layer doped with non-magnetic metal particles also has independent significance for the invention. Where shielding only magnetic fields are important, it can be used advantageously without electrically shielding shield layers, e.g. B. for magnetically shielded cables that are supposed to retain a high degree of flexibility.
- Fig. 1 shows an example of a coaxial cable with a single signal conductor A, which is surrounded by a dielectric B.
- the dielectric B is spanned by a first screen C made of a metal mesh.
- the first screen C is surrounded by a metal-doped, electrically non-conductive plastic intermediate layer D, which in turn is surrounded by a second screen E made of a metal mesh.
- the outermost layer of the cable is formed by a plastic jacket.
- metal-doped plastic intermediate layer D Particularly suitable materials for the metal-doped plastic intermediate layer D are PTFE (polytetrafluoroethylene), in which copper powder is preferably embedded.
- cables whose middle shielding or intermediate layer D is doped with copper particles have on the one hand a considerably higher shielding attenuation and on the other hand a high shielding attenuation up to substantially higher frequency ranges than with ferrite doping.
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Abstract
Elektromagnetische Abschirmung mit einer mindestens zweilagigen elektromagnetischen Abschirmung, deren eine Lage durch einen elektrischen Leiter wie einen Metallgeflechtschirm (C;D) gebildet ist und deren zweite Lage durch eine flexible, elektrisch nicht-leitende, mit nicht-magnetischen Metallteilchen dotierte Kunststoffschicht (D) gebildet ist.Electromagnetic shield with an at least two-layer electromagnetic shield, one layer of which is formed by an electrical conductor such as a metal braid shield (C; D) and the second layer of which is formed by a flexible, electrically non-conductive plastic layer (D) doped with non-magnetic metal particles is.
Description
Die Erfindung betrifft eine elektromagnetische oder magnetische Abschirmung und damit aufgebaute elektrische Kabel.The invention relates to electromagnetic or magnetic shielding and electrical cables constructed therewith.
Insbesondere bei Anwendungen im Hochfrequenzbereich ist es häufig erforderlich, einen oder mehrere Signalleiter eines elektrischen Kabels mit einer elektromagnetischen Abschirmung zu umgeben. Damit soll einerseits eine störende elektromagnetische Einstrahlung von außen auf das zu übertragende Signal und andererseits ein Abstrahlen des Signals nach außen verhindert werden.Particularly in applications in the high-frequency range, it is often necessary to surround one or more signal conductors of an electrical cable with an electromagnetic shield. This is intended on the one hand to prevent disturbing electromagnetic radiation from the outside onto the signal to be transmitted and on the other hand to prevent the signal from being emitted to the outside.
Für Hochfrequenzanwendungen
sind Kabel,
deren Abschirmung aus einem einfach geflochtenen Schirm besteht, häufig nicht ausreichend. Eine bessere Abschirmwirkung erreicht man mit zwei aufeinander geflochtenen Schirmen. Bei sehr hohen Anforderungen an die Abschirmwirkung, wie sie beispielsweise im Bereich der Raumfahrt, Luftfahrt, Telekommunikation und Datenverarbeitung gefordert wird, reicht auch eine derartige Abschirmung nicht aus. Für solche Anwendungsgebiete hat man Kabel mit dreilagiger Abschirmung geschaffen, wobei die Innenlage und die Außenlage je durch einen Metallgeflechtschirm und die Zwischenlage durch einen polykristallinen Werkstoff wie beispielsweise µ-Metall, metallisches Glas und dergleichen gebildet sind.For high frequency applications
are cables,
whose shielding consists of a simply braided shield, often not sufficient. A better shielding effect can be achieved with two braided shields. In the case of very high demands on the shielding effect, as is required, for example, in the field of space travel, aviation, telecommunications and data processing, such a shielding is also not sufficient. For such applications, cables with three-layer shielding have been created, the inner layer and the outer layer each being formed by a metal braid shield and the intermediate layer by a polycrystalline material such as, for example, μ-metal, metallic glass and the like.
Ein derartiger Abschirmungsaufbau führt jedoch zu Kabeln mit nur geringer Flexibilität und mit schwieriger Verarbeitung beim Anschließen an die Kontaktelemente von Steck verbindern. Außerdem erreicht man hiermit im wesentlichen nur eine Abschirmung elektrischer Feder, nicht aber magnetischer Felder. Desweiteren wirkt sich nachteilig aus, daß die elektrisch leitende Zwischenlage den Innenschirm und den Außenschirm elektrisch verbindet und daher die dreilagige Abschirmung im Grunde nur wie eine dickschichtige Abschirmung wirkt.Such a shield structure, however, leads to cables with only little flexibility and with difficult processing when connecting to the contact elements of plug connect. In addition, essentially only a shielding of electrical springs is achieved, but not magnetic fields. Furthermore, it has the disadvantage that the electrically conductive intermediate layer electrically connects the inner shield and the outer shield, and therefore the three-layer shield basically acts only as a thick-layer shield.
Aus der DE-OS 30 25 504 ist ein Koaxialkabel bekannt, das zwischen zwei Metallschirmen eine magnetische Schicht aufweist, bei der es sich um einen nicht-leitenden oder nur wenig leitenden magnetischen Mischstoff handelt, der durch Einmischen von Ferritstaub oder anderem magnetischen metallischen Staub in ein flexibles Kunststoffträgermaterial hergestellt werden kann.From DE-OS 30 25 504 a coaxial cable is known which has a magnetic layer between two metal shields, which is a non-conductive or only slightly conductive magnetic mixture which by mixing in ferrite dust or other magnetic metallic dust a flexible plastic carrier material can be produced.
Aus der US-PS 4 376920 ist es bekannt, bei einem Koaxialkabel zwischen zwei Flechtschirmen eine Zwischenschicht mit hohem Verlustfaktor unterzubringen, um eine hohe Ausbeitungsfunktion für den Weg zwischen den beiden Schirmschichten und damit eine möglichst längenunabhängige Abschirmwirkung zu erreichen. Als Zwischenschicht kann ein elektrisch gut isolierender Kunststoff verwendet werden, in den verlustbewirkende Pigmente oder andere Verbindungen nicht näher angegebener Art eingelagert sind.From US-
Aus den US-Patentschriften 3191132 und 3309633 sind elektrische Kabel bekannt, deren elektrische Leiter umgebendes flexibles, isolierendes Kunststoffmaterial eine Zumischung von Ferritteilchen aufweist, um eine Absorption elektromagnetischer Wellen hoher Frequenz zu erreichen, ohne eine Absorption solcher Wellen im niederfrequenten Bereich zu haben.From US Pat. Nos. 3191132 and 3309633 electrical cables are known whose electrical conductors surrounding flexible, insulating plastic material have an admixture of ferrite particles in order to achieve absorption of high-frequency electromagnetic waves without having such absorption in the low-frequency range.
Die Verwendung von dotierten Isolierschichten führt gegenüber Kabeln mit starren Abschirmschichten zu einer verbesserten Kabelflexibilität.The use of doped insulating layers leads to improved cable flexibility compared to cables with rigid shielding layers.
Für Anwendungsgebiete der zuvor beispielsweise genannten Art sollte die Abschirmdämpfung für einen möglichst großen Frequenzbereich größer als 100 dB sein, um Abstrahlung und Einstrahlung von störenden Signalen in einem möglichst großen Frequenzbereich zu verhindern.For areas of application of the type mentioned above, for example, the shielding attenuation should be greater than 100 dB for the largest possible frequency range in order to prevent radiation and radiation of interfering signals in the largest possible frequency range.
Elektromagnetische Strahlungen auf das zu übertragende Signal wirken sich vor allem bei Digitalsignalen dadurch negativ aus, daß die Impulsflanken abgeflacht werden, was zu Signalverfälschungen und zu einer Verringerung der möglichen Impulsfolgefrequenz führt.Electromagnetic radiation on the signal to be transmitted has a negative effect, particularly in the case of digital signals, in that the pulse edges are flattened, which leads to signal falsifications and a reduction in the possible pulse repetition frequency.
In vielen Bereichen der Technik ist auch ein Abstrahlen der zu übertragenden Impulse von dem Kabel auf andere elektronische Komponenten oder Signalleiter anderer Kabel unerwünscht. Auf den Gebieten der Telekommunikation und der Datenverarbeitung kann es zu unerwünschtem Nebensprechen kommen und wird durch die Abstrahlung unbefugte Datenanzapfung möglich.In many areas of technology, radiation of the pulses to be transmitted from the cable onto other electronic components or signal conductors of other cables is also undesirable. In the fields of telecommunications and data processing, unwanted crosstalk can occur and radiation can make unauthorized data tapping possible.
Eine Aufgabe der Erfindung besteht darin, eine elektromagnetische Abschirmung verfügbar zu machen, die bei hochflexiblem Kabelaufbau zu einer hohen Abschirmdämpfung sowohl elektrischer als auch magnetischer Felder in einem möglichst weiten Frequenzbereich führt.An object of the invention is to make available electromagnetic shielding which, with a highly flexible cable structure, leads to a high shielding attenuation of both electrical and magnetic fields in the widest possible frequency range.
Eine Lösung dieser Aufgabe ist im Anspruch 1 angegeben und kann den weiteren Ansprüchen gemäß vorteilhaft weitergebildet werden.A solution to this problem is specified in claim 1 and can advantageously be developed according to the other claims.
Da die eine Lage der Abschirmung aus metalldotiertem Kunststoff besteht und hochflexible Kunststoffe zur Verfügung stehen, braucht ein mit der erfindungsgemäßen Abschirmung versehenes Kabel keinerlei Einbuße an Flexibilität zu erleiden. Die außerordentlich guten elektromagnetischen Schirmdämpfungseigenschaften werden dadurch erreicht, daß das ein- bzw. abstrahlende magnetische Feld in der Abschirmlage aus mit nicht-magnetischen Metallteilchen dotiertem Kunststoff gebündelt wird.Since the one layer of the shield consists of metal-doped plastic and highly flexible plastics are available, a cable provided with the shield according to the invention does not have to suffer any loss of flexibility. The extraordinarily good electromagnetic shielding damping properties are achieved in that the magnetic field emitting or emitting is bundled in the shielding layer from plastic doped with non-magnetic metal particles.
Abschirmungen gegen elektrische Felder, die aus elektrischen Leitern bestehen, wirken dadurch, daß diese elektrischen Leiter eine Äquipotentialfläche bilden, die durch Außenanschluß beispielsweise auf das Potential 0 gelegt wird. Ladungsträger, die durch lokale elektrische Felder verursacht werden, fließen sofort ab, was die elektrische Abschirmwirkung hervorbringt. Je höher die elektrische Leitfähigkeit umso besser die elektrische Abschirmwirkung.Shields against electrical fields, which consist of electrical conductors, act in that these electrical conductors form an equipotential surface which is connected to the
Derartige elektrische Leiter bewirken jedoch keine oder nur eine sehr schwache Abschirmung gegenüber Magnetfeldern, wenn man einmal von sehr hohen Frequenzen im GHz-Bereich absieht. Insbesondere in relativ niedrigen Frequenzbereichen, beispielsweise im unteren MHz- oder gar KHz-Bereich, tritt jedoch praktisch keine magnetische Abschirmung auf.Such electrical conductors, however, have no or only a very weak shielding against magnetic fields, if one disregards very high frequencies in the GHz range. In particular in relatively low frequency ranges, for example in the lower MHz or even KHz range, there is practically no magnetic shielding.
Dadurch, daß man für die magnetisch abschirmende Abschirmlage Kunststoff verwendet, in den metallische Teilchen so eingebettet sind, daß der Kunst stoff nicht zum elektrischen Leiter wird, nach Art bekannter "elektrisch leitender Kunststoffe", sondern ein elektrischer Isolator bleibt, erreicht man eine verbesserte Abschirmungwirkung gebenüber magnetischen Feldern. Bettet man aber wie bei den bekannten Kabeln Ferritpulver in den Kunststoff ein, erreicht man eine Abschirmdämpfung, die nur relativ wenig über den als Mindestwert gewünschten 100 dB liegt, nur in einem relativ kleinen unteren Frequenzbereich.The fact that plastic is used for the magnetic shielding layer, in which metallic particles are embedded so that the art Substance does not become an electrical conductor, in the manner of known "electrically conductive plastics", but remains an electrical insulator, an improved shielding effect is achieved by means of magnetic fields. If, however, as in the case of the known cables, ferrite powder is embedded in the plastic, shielding attenuation which is only relatively little above the 100 dB desired as the minimum value is achieved only in a relatively small lower frequency range.
Verwendet man nicht-magnetische Metallteilchen, wie beispielsweise Kupferpulver, entstehen in diesen Metallteilchen vom hochfrequenten Magnetfeld hervorgerufene, induzierte Wirbelströme, die wiederum ein Magnetfeld verursachen, das dem äußeren Magnetfeld entgegengesetzt ist. Auch hier kommt es zu einer gebündelten Bindung des abzuschirmenden Magnetfeldes wie bei Ferrit-Dotierung. Allerdings nimmt die Wirbelstromstärke und damit die magnetische Abschirmwirkung mit zunehmender Magnetfeldstärke und steigender Frequenz zu, was nicht nur zu höherer Abschirmdämpfung als bei Ferrit-Dotierung an sich führt sonder zu einer Ausdehnung des Bereichs guter Abschirmdämpfung in viel höhere Frequenzregionen. Die erfindungsgemäße Maßnahme führt daher zu überraschend guten magnetischen Abschirmergebnissen.If non-magnetic metal particles, such as copper powder, are used, induced eddy currents are produced in these metal particles by the high-frequency magnetic field, which in turn cause a magnetic field that is opposite to the external magnetic field. Here too there is a bundled bond between the magnetic field to be shielded and ferrite doping. However, the eddy current strength and thus the magnetic shielding effect increases with increasing magnetic field strength and increasing frequency, which not only leads to higher shielding attenuation than with ferrite doping per se, but also extends the range of good shielding attenuation into much higher frequency regions. The measure according to the invention therefore leads to surprisingly good magnetic shielding results.
Besonders gute elektromagnetische Abschirmwirkungen erzielt man mit einer dreilagigen Abschirmung, deren innere und deren äußere Schirmlage je durch einen elektrischen Leiter wie insbesondere ein Metallgeflecht oder eine Metallfolie gebildet sind und deren Mittellage durch die metalldotierte Kunststoffschicht gebildet ist. Letztere führt zu einer elektrischen Isolierung zwischen innerer und äußerer elektrisch leitender Schirmlage. Dies bewirkt eine Reflexion des abzuschirmenden elektrischen Feldes an zwei elektrisch gesehen unterschiedlichen Schirmschichten. Dies führt zu einer besseren elektrischen Abschirmung als drei elektrisch leitende Schirmlagen, die miteinander in elektrischer Verbindung stehen und für die abzuschirmenden elektrischen Felder daher im wesentlichen nur wie eine einzige Schirmschicht wirken.Particularly good electromagnetic shielding effects are achieved with a three-layer shield, the inner and outer shield layers of which are each formed by an electrical conductor such as, in particular, a metal braid or a metal foil and whose middle layer is formed by the metal-doped plastic layer. The latter leads to electrical insulation between the inner ones and outer electrically conductive shield layer. This causes the electrical field to be shielded to be reflected on two electrically different shielding layers. This leads to better electrical shielding than three electrically conductive shield layers which are in electrical connection with one another and therefore essentially only act as a single shield layer for the electrical fields to be shielded.
Gegenüber der bekannten dreilagigen Abschirmung mit einem inneren Metallgeflechtschirm, einem äußeren Metallgeflechtschirm und einer dazwischen befindlichen mittleren Abschirmlage aus Ferrit-dotiertem Kunststoff führt die erfindungsgemäße Abschirmung mit einer Kunststoffzwischenschicht, in die nicht-magnetische Metallteilchen eingelagert sind, daher zu einer erheblich besseren magnetischen Abschirmung über einen sehr weiten Frequenzbereich, wobei eine gute Kabelflexibilität erhalten bleibt.Compared to the known three-layer shielding with an inner metal braid shield, an outer metal braid shield and an intermediate shielding layer made of ferrite-doped plastic, the shielding according to the invention with an intermediate plastic layer, in which non-magnetic metal particles are embedded, therefore leads to a considerably better magnetic shielding via a very wide frequency range, while maintaining good cable flexibility.
Ein mit der erfindungsgemäßen elektromagnetischen Abschirmung versehenes Kabel kann daher sowohl hohe Flexibilität aufweisen als auch eine überragende elektromagnetische Abschirmung.A cable provided with the electromagnetic shielding according to the invention can therefore have both high flexibility and an outstanding electromagnetic shielding.
Die flexible, mit nicht-magnetischen Metallteilchen dotierte, elektrisch nicht-leitende Kunststoffschicht hat auch selbständig Erfindungsbedeutung. Sie kann dort, wo es auf eine Abschirmung nur magnetischer Felder ankommt, ohne elektrisch abschirmende Schirmlagen vorteilhaft eingesetzt werden, z. B. für magnetisch abzuschirmende Kabel, die hohe Flexibilität behalten sollen.The flexible, electrically non-conductive plastic layer doped with non-magnetic metal particles also has independent significance for the invention. Where shielding only magnetic fields are important, it can be used advantageously without electrically shielding shield layers, e.g. B. for magnetically shielded cables that are supposed to retain a high degree of flexibility.
Die Erfindung wird nun anhand einer Ausführungsform näher erläutert. In den Zeichnungen zeigen:
- Fig. 1 eine Ausführungsform der Erfindung; und
- Fig. 2 Abschirmdämpfungsverläufe in Abhängigkeit von der Frequenz für ein Kabel gemäß Fig. 1 mit einer bekannten und mit einer erfindungsgemäßen Abschirmschicht.
- 1 shows an embodiment of the invention; and
- Fig. 2 shielding attenuation curves as a function of frequency for a cable according to FIG. 1 with a known and with a shielding layer according to the invention.
Fig. 1 zeigt als Beispiel ein Koaxialkabel mit einem einzigen Signalleiter A, der von einem Dielektrikum B umgeben ist. Das Dielektrikum B wird von einem ersten Schirm C aus einem Metallgeflecht umspannt. Den ersten Schirm C umgibt eine metalldotierte, elektrisch nicht-leitende Kunststoffzwischenschicht D, die ihrerseits von einem zweiten Schirm E aus einem Metallgeflecht umgeben wird. Die äußerste Schicht des Kabels wird durch einen Kunststoffmantel gebildet.Fig. 1 shows an example of a coaxial cable with a single signal conductor A, which is surrounded by a dielectric B. The dielectric B is spanned by a first screen C made of a metal mesh. The first screen C is surrounded by a metal-doped, electrically non-conductive plastic intermediate layer D, which in turn is surrounded by a second screen E made of a metal mesh. The outermost layer of the cable is formed by a plastic jacket.
Als Materialien für die metalldotierte Kunststoffzwischenschicht D eignen sich insbesondere PTFE (polytetrafluoräthylen), in das vorzugsweise Kupferpulver eingebettet ist.Particularly suitable materials for the metal-doped plastic intermediate layer D are PTFE (polytetrafluoroethylene), in which copper powder is preferably embedded.
Messungen an verschiedenen Abschirmungen haben im Frequenzbereich zwischen 0,25 MHz und 110 MHz folgende Schirmdämpfungen ergeben:
- einfach geflochtener Schirm: ca. 60 dB
- zwei aufeinander geflochtene Schirme: ca. 85 dB
- zwei aufeinander geflochtene Schirme mit einer Zwischenschicht aus mit metallischem Pulver dotiertem Kunststoff: > 100 dB
- a) bei Verwendung von Ferrit-dotiertem Kunststoff bis 8 MHz und einem Maximum von ca. 107 dB bei etwa 2 MHz (Kurve F in Fig. 2);
- b) bei Verwendung von mit nicht-magnetischen Metallteilchen dotiertem Kunststoff bis etwa 90 MHz und einem Maximum von etwa 118 dB bei ca. 8 MHz (Kurve Cu in Fig. 2).
- simple braided screen: approx. 60 dB
- two shields braided together: approx. 85 dB
- two shields braided on top of each other with an intermediate layer made of plastic doped with metallic powder:> 100 dB
- a) when using ferrite-doped plastic up to 8 MHz and a maximum of about 107 dB at about 2 MHz (curve F in Fig. 2);
- b) when using plastic doped with non-magnetic metal particles up to approximately 90 MHz and a maximum of approximately 118 dB at approximately 8 MHz (curve Cu in FIG. 2).
Fig. 2 zeigt also, daß Kabel, deren mittlere Abschirm- oder Zwischenschicht D mit Kupferteilchen dotiert ist, einerseits eine erheblich höhere Schirmdämpfung und andererseits hohe Schirmdämpfung bis in wesentlich höhere Frequenzbereiche als bei Ferrit-Dotierung aufweisen.2 thus shows that cables whose middle shielding or intermediate layer D is doped with copper particles have on the one hand a considerably higher shielding attenuation and on the other hand a high shielding attenuation up to substantially higher frequency ranges than with ferrite doping.
Claims (9)
dadurch gekennzeichnet,
daß die zweite Abschirmlage durch eine flexible, mit nicht-magnetischen Metallteilchen dotierte, elektrisch nicht-leitende Kunststoffschicht (D) gebildet ist.1. Electromagnetic shielding with at least two shielding layers, one of which is formed by an electrical conductor in the form of a metal braid or a metal foil,
characterized by
that the second shielding layer is formed by a flexible, electrically non-conductive plastic layer (D) doped with non-magnetic metal particles.
dadurch gekennzeichnet,
daß in die Kunststoffschicht (D) metallisches Pulver eingebettet ist.2. Shielding according to claim 1,
characterized,
that metallic powder is embedded in the plastic layer (D).
dadurch gekennzeichnet,
daß als Kunststoff Polytetrafluoräthylen (PTFE) verwendet wird.3. Shielding according to claim 1 or 2,
characterized,
that polytetrafluoroethylene (PTFE) is used as the plastic.
dadurch gekennzeichnet,
daß der Kunststoff mit Kupfer dotiert ist.4. Shielding according to one of claims 1 to 3,
characterized,
that the plastic is doped with copper.
dadurch gekennzeichnet,
daß der Kunststoff mit Pulver eines metallischen Glases dotiert ist.5. Shielding according to one of claims 1 to 4,
characterized,
that the plastic is doped with powder of a metallic glass.
dadurch gekennzeichnet,
daß die Abschirmung dreilagig ist und als Innenlage (C) und als Außenlage (E) je ein Metallgeflecht vorgesehen ist und die metalldotierte Kunststoffschicht die Zwischenlage (D) bildet.6. Shielding according to one of the preceding claims,
characterized,
that the shield has three layers and a metal braid is provided as the inner layer (C) and the outer layer (E) and the metal-doped plastic layer forms the intermediate layer (D).
gekennzeichnet durch
eine elektromagnetische Abschirmung nach einem der Ansprüche 1 bis 6.7. Electrical cable with at least one signal conductor,
marked by
an electromagnetic shield according to one of claims 1 to 6.
gekennzeichnet durch
eine flexible, mit nicht-magnetischen Metallteilchen dotierte, elektrisch nicht-leitende Kunststoffschicht.8. Magnetic shielding
marked by
a flexible, electrically non-conductive plastic layer doped with non-magnetic metal particles.
gekennzeichnet durch
eine magnetische Abschirmung nach Anspruch 8.9. Electrical cable with at least one signal conductor,
marked by
a magnetic shield according to claim 8.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863625631 DE3625631A1 (en) | 1986-07-29 | 1986-07-29 | ELECTROMAGNETIC SHIELDING |
| DE3625631 | 1986-07-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0254964A2 true EP0254964A2 (en) | 1988-02-03 |
| EP0254964A3 EP0254964A3 (en) | 1989-05-24 |
Family
ID=6306213
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87110235A Withdrawn EP0254964A3 (en) | 1986-07-29 | 1987-07-15 | Magnetic or electromagnetic shield and electrical cable equipped with it |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4871883A (en) |
| EP (1) | EP0254964A3 (en) |
| JP (1) | JPS63170811A (en) |
| DE (1) | DE3625631A1 (en) |
| IL (1) | IL83300A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102014223134A1 (en) | 2014-11-13 | 2016-05-19 | Robert Bosch Gmbh | Electric drive system and motor vehicle with an electric drive system |
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-
1986
- 1986-07-29 DE DE19863625631 patent/DE3625631A1/en active Granted
-
1987
- 1987-05-22 JP JP62125673A patent/JPS63170811A/en active Pending
- 1987-07-15 EP EP87110235A patent/EP0254964A3/en not_active Withdrawn
- 1987-07-23 US US07/076,623 patent/US4871883A/en not_active Expired - Lifetime
- 1987-07-23 IL IL83300A patent/IL83300A/en not_active IP Right Cessation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB633190A (en) * | 1947-12-31 | 1949-12-12 | Osbert Linn Ratsey | Improvements in screened electric cables |
| DE2547152A1 (en) * | 1975-10-21 | 1977-04-28 | Tenge Hans Werner | Screened electric cables - provided with PTFE foil unsintered and filled with graphite or carbon fillers for controlled conduction |
| US4376920A (en) * | 1981-04-01 | 1983-03-15 | Smith Kenneth L | Shielded radio frequency transmission cable |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102014223134A1 (en) | 2014-11-13 | 2016-05-19 | Robert Bosch Gmbh | Electric drive system and motor vehicle with an electric drive system |
Also Published As
| Publication number | Publication date |
|---|---|
| IL83300A (en) | 1991-01-31 |
| IL83300A0 (en) | 1987-12-31 |
| US4871883A (en) | 1989-10-03 |
| DE3625631C2 (en) | 1990-02-08 |
| EP0254964A3 (en) | 1989-05-24 |
| DE3625631A1 (en) | 1988-02-04 |
| JPS63170811A (en) | 1988-07-14 |
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