EP0383142B1 - Mittel zum Dämpfen elektromagnetischer Wellen, Verfahren zur Herstellung sowie Verwendung des Mittels - Google Patents

Mittel zum Dämpfen elektromagnetischer Wellen, Verfahren zur Herstellung sowie Verwendung des Mittels Download PDF

Info

Publication number: EP0383142B1
Authority: EP; European Patent Office
Prior art keywords: water; means according; calcium silicate; absorber; hydrated calcium
Prior art date: 1989-02-15
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.): Expired - Lifetime

Application number

EP90102253A

Other languages

German (de)

English (en)

French (fr)

Other versions

EP0383142A1 (de

Inventor

Klaus Friedrich Lippe

Manfred Lebherz

Werner Prof.-Dr. Wiesbeck

Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Ytong AG

Original Assignee

Ytong AG

Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)

1989-02-15

Filing date

1990-02-05

Publication date

1994-08-24

1990-02-05 Application filed by Ytong AG filed Critical Ytong AG

1990-08-22 Publication of EP0383142A1 publication Critical patent/EP0383142A1/de

1994-08-24 Application granted granted Critical

1994-08-24 Publication of EP0383142B1 publication Critical patent/EP0383142B1/de

2010-02-05 Anticipated expiration legal-status Critical

Status Expired - Lifetime legal-status Critical Current

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Classifications

- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems

Definitions

the invention relates to a means for damping electromagnetic waves, a method for producing and using the means.
absorbers are used, which ensure good damping of the electromagnetic waves in a broad frequency band.
Known absorber materials consist of polyurethane foam, which is impregnated with carbon-containing latex.
the absorbers made of this material require a considerable amount of space, so that the space requirement and in this respect the costs are considerable.
these are Absorber based on polyurethane foam very easily combustible, so that there is a high risk of fire.
the gas concrete Because of its high air pore content, which causes a low dielectric constant, the gas concrete is generally suitable for broadband camouflage of buildings against location with microwaves, but the low strength of a component caused by the very high air pore content, which forces large-volume construction, is criticized. It is therefore proposed in the cited document to ensure that by varying the composition of the base materials and the air content, the dielectric constant and the loss angle of the building material within the layer increase in the direction of propagation of the electromagnetic waves penetrating from outside. This should be made possible by the fact that very large air pores are generated, that the air pore content in the surface area is chosen to be very high and reduced towards the inside and that the known loss-generating substances are added. These measures make the component very expensive.
a waterproof outer layer is proposed, which but must not cause reflection.
This very thin outer layer is created by briefly, strongly heating the surface in question after the foaming process, but before the final hardening, as a result of which the outer gas bubbles are to collapse and a very hard and very thin surface layer is to be formed without any pore.
a hot metal plate on the surface should be very smooth, so that rainwater can drain well and dirt of all kinds can not adhere. The generation of such a surface is difficult and makes the component even more expensive.
the object of the invention is to provide a means for absorbing or damping electromagnetic waves, the damping properties of which are at least as good as those of the gas concrete and the damping properties of which are essentially retained.
the invention thus creates a porous absorption material for electromagnetic waves that can be manufactured according to the easily controllable gas concrete technology, the properties of which are retained for a long time.
a product that essentially consists of calcium silicate hydrate phases in addition to air pores and residual quartz, which have a high crystal water content. It was found that these phases result in better damping than gas concrete, the damping depending on the crystal water content preserved. It has been surprisingly found that the damping becomes less if the crystal water content is reduced, which can be caused in an uncontrollable manner, for example, by the action of heat. It is therefore important to ensure that the crystal water content is maintained and / or to prevent water contained in the absorber material from escaping.
An impregnation is advantageous, which allows water and / or water vapor to penetrate into the material, but prevents it from escaping.
a particularly effective seal is achieved with a coating based on epoxy resin, for example Disbon coating no. 441, which is expediently sprayed, for example, over the entire surface of the material.
the material can also be impregnated with liquid epoxy resin.
the autoclave should be cured at temperatures of 170 to 210 ° C to 4 to 12 hours.
the alkalis advantageously influence the phase formation in such a way that essentially crystal water-rich and stable, i.e. form the crystal water holding phases. It has been shown that the crystal water content of the absorber material should be above 10 M%, phases which are still partially amorphous being advantageous because these phases have a particularly high chemically bound "crystal water content".
the chemically bound water content is combined with an absorptively bound water content, i.e. the absorber material is additionally enriched with water, e.g. soaked in water, or you make sure that the so-called autoclave moisture is retained.
the absorptively bound water can also completely or partially fill the pores. So that this water is not lost, e.g. the surface of the material - as described above - impregnated and / or sealed so that the absorber properties of the material are retained. Amounts of absorptively bound water of 20 to 40% by mass are advantageous.
the agent according to the invention is preferably used with a bulk density of 300 to 800 kg / m3 and a crystal water content of 10 to 20 M%.
the agent according to the invention can also be mixed with carbon and / or ferrite in an amount of 5 to 30% by mass, as a result of which the damping values can be improved in a manner known per se.
the invention also relates to an absorber component for electromagnetic waves, which is constructed from the agent according to the invention.
the absorber component can preferably be designed as a plate or building block, which can have any spatial shape.
the absorber component 1 according to the invention according to FIG. 1 consists of the porous calcium silicate hydrate material described above. It is designed as a pyramid absorber and has a multiplicity of individual pyramids 2 on a base plate 3 side by side and one behind the other, as can be seen from FIG. 2.
the angle ⁇ enclosed by the side surfaces 4 of a pyramid in the pyramid tip is preferably 15 to 40 °.
the height k of the pyramids 2 are dependent on the lowest operating frequency.
the thickness s of the base plate 3 is primarily dependent on the total loss which is to be achieved.
the advantage of the pyramid structure is the uniform damping with regard to the angle of incidence and the polarization as well as a high damping due to the surface structure. This attenuation can be up to 60 dB.
the advantage of the absorber component according to the invention over the known absorbers with a pyramid structure consists in the fact that the absorber according to the invention can have a much smaller depth at the same frequency and nevertheless a broadband effectiveness of the damp
This absorber component 1 in turn consists of a multiplicity of pyramids 2, which start from a base plate 3.
the porous calcium silicate hydrate material according to the invention serves as the production material.
the space 5 between the individual pyramids 2 is filled with a porous calcium silicate hydrate which has a lower density than the material of the pyramids themselves and thus a favorable reflection behavior resulting from the lower density.
This configuration according to the invention creates an absorber with at least the same effectiveness as a pure pyramid absorber according to FIG. 2, but with the advantage that this absorber has a completely flat and even surface.
the absorber component designed in this way can be coated in the usual way as in the known building materials, for example with a coat of paint.
This absorber component according to the invention thus has a completely flat surface on the side facing the wave incidence.
the absorber components can have a side length of 30 to 50 cm.
the height of the pyramids is preferably three times the thickness of the base plate 3 and the sum of the height of the pyramids and the thickness of the base plate is ⁇ 30 cm.
the base plate 3 can be reinforced by flat absorber components.
the absorber component according to the invention can be chemically bound water in a range from 10 to 20 M% and, for example, by adding further admixtures, preferably made of carbon and / or ferrite particles with a proportion of 5 to 30 M% , 1 to 30 GHz can be optimized in terms of its damping properties.

Landscapes

Building Environments (AREA)
Curing Cements, Concrete, And Artificial Stone (AREA)
Golf Clubs (AREA)
Aerials With Secondary Devices (AREA)
Aftertreatments Of Artificial And Natural Stones (AREA)
Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Magnetic Record Carriers (AREA)

EP90102253A 1989-02-15 1990-02-05 Mittel zum Dämpfen elektromagnetischer Wellen, Verfahren zur Herstellung sowie Verwendung des Mittels Expired - Lifetime EP0383142B1 (de)

Applications Claiming Priority (2)

Application Number	Priority Date	Filing Date	Title
DE3904576		1989-02-15
DE3904576		1989-02-15

Publications (2)

Publication Number	Publication Date
EP0383142A1 EP0383142A1 (de)	1990-08-22
EP0383142B1 true EP0383142B1 (de)	1994-08-24

Family

ID=6374157

Family Applications (1)

Application Number	Title	Priority Date	Filing Date
EP90102253A Expired - Lifetime EP0383142B1 (de)	1989-02-15	1990-02-05	Mittel zum Dämpfen elektromagnetischer Wellen, Verfahren zur Herstellung sowie Verwendung des Mittels

Country Status (4)

Country	Link
EP (1)	EP0383142B1 (es)
AT (1)	ATE110497T1 (es)
DE (1)	DE59006865D1 (es)
ES (1)	ES2018767T3 (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number	Priority date	Publication date	Assignee	Title
DE10122472B4 (de) *	2000-05-31	2004-05-13	Colfirmit Rajasil Gmbh & Co. Kg	Verwendung eines Pulvers oder Granulates aus Ferrit
DE102007058480A1 (de) *	2007-12-04	2009-06-10	Frankonia Handels- und Vertriebsgesellschaft für chemisch- und elektrotechnische Produkte mbH	Absorber zur breitbandigen Absorption von elektromagnetischen Wellen im Frequenzbereich von 1 bis 18 GHz und Verfahren zu dessen Herstellung

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number	Priority date	Publication date	Assignee	Title
DE4014453C2 (de) *	1990-05-06	1994-09-08	Gruenzweig & Hartmann	Elektrisch leitfähiges Flächenelement sowie Verfahren zur Herstellung desselben
DE4201871A1 (de) *	1991-03-07	1992-09-10	Feldmuehle Ag Stora	Bauteil zur absorption elektromagnetischer wellen und seine verwendung
DE4223177C2 (de) *	1992-07-15	1994-06-16	Cerasiv Gmbh	Werkstoff zur Absorption und Abschirmung elektromagnetischer Wellen, Verfahren zu dessen Herstellung und dessen Verwendung
DE69513572T2 (de) *	1994-06-23	2000-03-30	Takenaka Corp., Osaka	Wellenabsorbierende Zusammensetzung, Absorberelement für Funkwellen, Funkwellenabsorber und Verfahren zur Herstellung von Absorberelementen
CN109516744B (zh) *	2019-01-21	2021-12-14	河北工业大学	一种基于3d打印的波浪形电磁吸波混凝土结构

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number	Priority date	Publication date	Assignee	Title
US2464006A (en) *	1944-04-28	1949-03-08	Philco Corp	Radio wave absorption device
DE1174679B (de) *	1960-02-02	1964-07-23	Erhard Mueller	Verfahren zur Herstellung von mit Kunststoff vergueteten Formkoerpern aus Beton

1990
- 1990-02-05 ES ES90102253T patent/ES2018767T3/es not_active Expired - Lifetime
- 1990-02-05 DE DE59006865T patent/DE59006865D1/de not_active Expired - Fee Related
- 1990-02-05 AT AT90102253T patent/ATE110497T1/de not_active IP Right Cessation
- 1990-02-05 EP EP90102253A patent/EP0383142B1/de not_active Expired - Lifetime

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number	Priority date	Publication date	Assignee	Title
DE10122472B4 (de) *	2000-05-31	2004-05-13	Colfirmit Rajasil Gmbh & Co. Kg	Verwendung eines Pulvers oder Granulates aus Ferrit
DE10122472B8 (de) *	2000-05-31	2004-09-02	Colfirmit Rajasil Gmbh & Co. Kg	Verwendung eines Pulvers oder Granulates aus Ferrit
DE102007058480A1 (de) *	2007-12-04	2009-06-10	Frankonia Handels- und Vertriebsgesellschaft für chemisch- und elektrotechnische Produkte mbH	Absorber zur breitbandigen Absorption von elektromagnetischen Wellen im Frequenzbereich von 1 bis 18 GHz und Verfahren zu dessen Herstellung

Also Published As

Publication number	Publication date
ATE110497T1 (de)	1994-09-15
ES2018767A4 (es)	1991-05-16
EP0383142A1 (de)	1990-08-22
ES2018767T3 (es)	1994-12-16
DE59006865D1 (de)	1994-09-29

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1990-11-21	ITCL	It: translation for ep claims filed	Representative=s name: ING. A. GIAMBROCONO & C. S.R.L.
1990-12-19	GBC	Gb: translation of claims filed (gb section 78(7)/1977)
1991-01-02	TCNL	Nl: translation of patent claims filed
1991-01-18	EL	Fr: translation of claims filed
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