CA2003074C - Structure for the absorption of electromagnetic waves - Google Patents
Structure for the absorption of electromagnetic waves Download PDFInfo
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- CA2003074C CA2003074C CA002003074A CA2003074A CA2003074C CA 2003074 C CA2003074 C CA 2003074C CA 002003074 A CA002003074 A CA 002003074A CA 2003074 A CA2003074 A CA 2003074A CA 2003074 C CA2003074 C CA 2003074C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/08—Metals
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
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- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
- B32B2307/212—Electromagnetic interference shielding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2323/00—Polyalkenes
- B32B2323/04—Polyethylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2325/00—Polymers of vinyl-aromatic compounds, e.g. polystyrene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2327/00—Polyvinylhalogenides
- B32B2327/06—PVC, i.e. polyvinylchloride
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/16—Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
Abstract
Structure pour l'absorption d'ondes électromagnétiques comportant un empilement de couches minces An obtenu à partir d'une couche A en un matériau choisi parmi les polymères semiconducteurs et les polymères chargés, et d'une couche B en un matériau choisi parmi les polymères isolants, le polyéthylène, le polystyrène, le polychlorure de vinyle, l'empilement An présentant en outre une séquence f lui conférant une organisation fractale.Structure for the absorption of electromagnetic waves comprising a stack of thin layers An obtained from a layer A of a material chosen from semiconductor polymers and charged polymers, and from a layer B of a material chosen from polymers insulators, polyethylene, polystyrene, polyvinyl chloride, stack An also having an f sequence giving it a fractal organization.
Description
4 ~ ~41~o ~3:~7~
Structure pour l'absorption d'ondes électromagnétiques La présente invention concerne une structure pour l'absorption d'ondes électromagnétiques, notamment dans la bande des ondes radar comprise entre 8 et 12 GHz.
On sait que certains polymères peuvent être utilisés comme des absorbants d'ondes électromagnétiques ; de telles indications sont données par exemple par A. FELDBLUM (1981 - J.POL.SCI.19,173).
Ainsi ont été étudiées les propriétés d'absorption du polyacétylène, du polyparaphénylène et du polythiophène vis-à-vis des ondes dont les fréquences sont comprises entre 100 Mhz et 10 GHz.
En général le problème est schématisé de la manière suivante.
Il s'agit de disposer d'un matériau stable à l'air ambiant, et dans un domaine de températures compris entre - 100~C et + 100~C, dont la conductivité effective qrdoit, si l'on s'en tient à la littérature, tendre vers 10 (ohm.cm) ; sa sensibilité aux variations de température doit être faible et sa permittivité relative par rapport à
l'air ~ doit être la plus proche possible de la valeur 1 pour rendre maximale l'absorption de l'onde incidente et quasiment nulle sa réflexion sur la face d'entrée.
Or les polymères précités, en particulier lorsqu'ils sont dopés - pour répondre aux conditions de conductivité, ne répondent pas intrin-sèquement à ces conditions, notamment en ce qui concerne d'une part la stabilité à l'air et aux variations de température, et d'autre part les facultés d'absorption, en particulier lorsqu'ils sont mélangés afin de former des monocouches composites avec des polymères à caractères diélectriques.
Par ailleurs il existe des polymères composites métalliques, en particulier chargés en fer, déjà dans le domaine commercial et vendus par la Société Emerson et Cumming. Ces polymères présentent l'inconvé-nient d'être très denses et de faire intervenir un moment magnétiqueimportant, ce qui a pour conséquence de faire apparaître un pic dans le spectre d'absorption.
La présente invention a pour but de réaliser une structure absorbante permettant d'éviter ces inconvénients et particulièrement performante dans le domaine de fréquences compris entre 8 et 12 GHz, ~ 2003074 avec un coefficient d'absorption plat dans la gamme de fréquences considérée.
La présente invention a pour objet une structure pour l'absorption d'ondes électromagnétiques, en particulier dans la bande 8 à 12 GHz, caractérisée par le fait qu'elle comporte un empilement de couches minces A obtenu à partir d'une couche A en un matériau choisi parmi les polymères semiconducteurs et les polymères chargés, et d'une couche B en un matériau choisi parmi les polymères isolants, le polyéthylène, le polystyrène, le polychlorure de vinyle, les composés fluorés tels que le PVDF, l'empilement A présentant en outre une séquence f telle que :
A1 = f(A, B) B1 = g(A, 8) A2 = f(Al, Bl) B2 = g(Al, Bl) n ( n-1' Bn-1) Bn = g(An 1' Bn 1) Les fonctions f et g restant constantes tout au long de l'itération, ledit empilement présente une organisation fractale.
On peut, à titre d'exemples, obtenir les empilements A suivants :
An = An-1 Bn-1 An-l avec n n-1 n-l n-l, A1 = ABA et Bl = BBB
ou An = An_1 Bn_1 An-1 ec n n-1 n-1 n-l, A1 = ABA et B1 = AAA
ou A = A B A B A
n n-1 n-1 n-1 n-1 n-1 avec Bn = Bn-1 Bn-1 Bn-1 Bn-l Bn-1, Al = ABABA, Bl = BBBB8 ou A = A B A B A
n n-l n-1 n-l n-1 n-l avec Bn = An-1 An-1 An-1 An-1 n-1, Al = ABABA, Bl = AAAAA
ou An = An 1 Bn-l An-l Bn-l avec Bn = Bn-l Bn-l Bn-l Bn-l, Al = ABAB, Bl = BBBB
ou A = A B A B
n n-1 n-1 n-1 n-1 n n-1 An-l An-l An-l, Al = ABAB, Bl = AAAA
30 ou A = A A B B
n n-l n-l n-l n-l avec Bn = Bn-l Bn-1 Bn-1 Bn-1, Al = AABB et Bl = BBBB
20~'~07 ou A = A B A B
n n-1 n-1 n-1 n-1 a ec n n-1 n-1 n-1 n-1, A1 = ABAB, Bl = AAAA
ou A = A A B B
n n-1 n-1 n-1 n-1, avec Bn = Bn-1 Bn-1 Bn-1 Bn-1, A1 = AABB et B1 = BBBB
5 ou A = A A B B
n n-1 n-1 n-1 n-1 avec Bn = An-1 An-1 An-1 An-1, A1 = AABB et B1 = AAAA
La finalité d'une telle structure est en particulier de conduire à
une incommensurabilité entre l'onde qui doit être dirigée et les caractéristiques géométriques de la structure. Il peut être montré que celle-ci doit conduire à une localisation de l'énergie à l'intérieur même de la structure donc à une absorption totale.
Selon un mode de réalisation préférentiel, le matériau de la couche A (ou B) présente une structure composite comprenant - un polymère à base de polyéthylène et d'un polymère isolant, la proportion en poids de polyéthylène étant comprise entre 55 % et 75 %
- une charge de poudre de nickel dont la granulométrie est comprise entre 1 ~m et 20 ~m, avec un taux de charges en volume compris entre 5 %
et 35 %.
Le matériau de la couche B (ou A) est formé par ledit polymère à base de polyéthylène et de polymère isolant, mais exempt de charges.
Les caractéristiques suivantes constituent des modes de réalisation préférentiels :
Ladite granulométrie est comprise entre 3 ~m et 20 ~m, et particulière-ment de l'ordre de 5 ~m.
Ledit taux de charge est compris entre 15 % et 25 %, et particulièrement de l'ordre de 19 %.
La proportion de polyéthylène dans le polymère est de l'ordre de 65 %.
Selon une autre réalisation, le matériau de la couche A (ou B) présente une structure composite comprenant 30 - un polymère isolant comportant du polyéthylène, la proportion en poids de polyéthylène étant comprise entre 55 et 75 %, - une charge de polymères conducteurs dont la granulométrie est comprise entre 0,5 ~m et 100 ~m et le taux entre 5 et 90 % dans ce polymère isolant, 35 - et par le fait que la couche complémentaire B (ou A) est formée par 03~7~
ledit polymère isolant.
Ledit polymère isolant est choisi parmi l'EPDM, l'acrylonitrile butadiène styrène, le monomère copolymère éthylène propylène, le polyéthylène haute pression, le polyéthylène basse pression, le polyéthylène basse pression linéaire, le polyamide (nylon), le polyacry-lonitrile, le téréphthalate de polybutylène, le polycarbonate, le polyéthylène, le polyéther ether ketone, l'oxyde de polyéthylène, le téréphthalate de polyéthylène, le polypropylène, l'oxyde de polyphénylène, le sulfure de polyphénylène, le polystyrène, le polyuréthane.
D'autres caractéristiques et avantages de la présente invention apparaltront au cours de la description suivante d'exemples de réalisation donnés à titre illustratif mais nullement limitatif. Dans le dessin annexé :
- La figure 1 montre des variations du facteur de réflexion R de diverses structures selon l'invention en fonction de la fréquence f en GHz.
- La figure 2 est analogue à la figure 1, pour le domaine compris entre 8 et 12 GHz.
- La figure 3 est analogue à la figure 2, pour d'autres structures selon l'invention.
On part d'un matériau permettant de réaliser une couche A et dont la structure composite comporte :
- un polymère à base de polyéthylène et d'EPDM, la proportion (en poids) de polyéthylène étant 65 %, - une char~e de poudre de nickel dont la granulométrie est de l'ordre de 5 ~m, avec un taux de charge en volume de l'ordre de 24 %.
On réalise également une couche B comportant uniquement le polymère précité.
On réalise un empilement d'ordre 1 : A1 = ABA, c'est-à-dire comportant deux couches A avec une couche B intercalaire. Cet empilement est déposé sur une surface métallique.
Le tableau 1 mentionne les caractéristiques électriques et mécaniques de ces couches : ~ est la permittivité relative par rapport à
l'air, ~ la perméabilité relative et ~ la résistivité.
~ ~00~07~
,.................................... ~
TABLEAU
¦ ¦ A ¦ B ¦ A
H
1~ 1 3 1 3 1 3 ll H
I " 1 1 1 1 11 1 11 ¦ ~ Qcm ¦ 0,05 ~ 0,05 I
I Epaisseur llm ¦ 750 ¦ 750 ¦ 750 H
Il l 11 11 11 On réalise également des empilements:
- d'ordre 2 A2 = AlBlAl avec Bl = BBB
d ordre 3 3 2 2 2 2 1 1 1 d ordre 4 A4 3 3 3 3 2 2 2 - d'ordre 5 A5 = A4B4A4 avec B4 = B3B3B3-L'épaisseur totale de ces empilements est toujours de 2250 llm.
La figure 1 montre les variations du facteur de réflexion R sur ces différents empilements Al, A2, A3, A4, A5 en fonction de la fréquence f 25 en GHz.
La figure 2 comporte les mêmes courbes que la figure 1 mais àl'échelle agrandie, dans la gamme 8 à 12 GHz. On voit l'intérêt de l'empilement A3 dans cette gamme de fréquences en particulier pour l'ordre 3. Cet empilement présentant une épaisseur de 2,25 mm autorise 30 une absorption comprise entre 90 et 99 %, qui est bien meilleure que celle de Al. Le choix de l'ordre d'itération est donc extrêmement important.
On réalise le même type d'empilements que précédemment avec A'l, A'2, A'3, A'4, A'5 tels que l'épaisseur totale de l'empilement soit 35 égale à 1800 ~m.
~1~0307~
La figure 3 analogue à la figure 2 montre l'intérêt de l'empilement d'ordre de 3 dans le domaine compris entre 8 et 12 GHz.
Bien entendu l'invention n'est pas limitée aux modes de réalisation qui ont été décrits, notamment en ce qui concerne les matériaux et les 5 épaisseurs des couches des empilements. 4 ~ ~ 41 ~ o ~ 3: ~ 7 ~
Structure for the absorption of electromagnetic waves The present invention relates to a structure for absorption electromagnetic waves, especially in the radar wave band between 8 and 12 GHz.
It is known that certain polymers can be used as electromagnetic wave absorbents; such indications are data for example by A. FELDBLUM (1981 - J.POL.SCI.19,173).
Thus, the absorption properties of polyacetylene, polyparaphenylene and polythiophene towards waves with frequencies between 100 MHz and 10 GHz.
In general the problem is schematized in the following way.
This involves having a material that is stable in ambient air, and in a temperature range between - 100 ~ C and + 100 ~ C, including effective conductivity qrdoit, if we stick to the literature, tend towards 10 (ohm.cm); its sensitivity to variations in temperature must be low and its relative permittivity compared to the air ~ must be as close as possible to the value 1 to make maximum absorption of the incident wave and almost zero its reflection on the entrance face.
Now the aforementioned polymers, in particular when they are doped - to meet the conductivity conditions, do not respond intrinsically-under these conditions, in particular with regard to the stability to air and temperature variations, and on the other absorption properties, especially when mixed to form composite monolayers with polymers with characters dielectric.
In addition, there are metallic composite polymers, in individuals loaded with iron, already in the commercial field and sold by the Emerson and Cumming Company. These polymers have the disadvantage deny being very dense and involving an important magnetic moment, which has the consequence of causing a peak to appear in the absorption spectrum.
The object of the present invention is to produce a structure absorbent to avoid these drawbacks and particularly efficient in the frequency range between 8 and 12 GHz, ~ 2003074 with a flat absorption coefficient in the frequency range considered.
The present invention relates to a structure for absorption electromagnetic waves, in particular in the 8 to 12 GHz band, characterized by the fact that it comprises a stack of layers thin A obtained from a layer A of a material chosen from semiconductor polymers and charged polymers, and a layer B in a material chosen from insulating polymers, polyethylene, polystyrene, polyvinyl chloride, fluorinated compounds such as PVDF, the stack A further having a sequence f such that:
A1 = f (A, B) B1 = g (A, 8) A2 = f (Al, Bl) B2 = g (Al, Bl) n (n-1 'Bn-1) Bn = g (An 1' Bn 1) The functions f and g remaining constant throughout the iteration, said stack has a fractal organization.
We can, for example, obtain the following stacks A:
An = An-1 Bn-1 An-l with n n-1 nl nl, A1 = ABA and Bl = BBB
or An = An_1 Bn_1 An-1 ec n n-1 n-1 nl, A1 = ABA and B1 = AAA
or A = ABABA
n n-1 n-1 n-1 n-1 n-1 with Bn = Bn-1 Bn-1 Bn-1 Bn-l Bn-1, Al = ABABA, Bl = BBBB8 or A = ABABA
n nl n-1 nl n-1 nl with Bn = An-1 An-1 An-1 An-1 n-1, Al = ABABA, Bl = AAAAA
or An = An 1 Bn-l An-l Bn-l with Bn = Bn-l Bn-l Bn-l Bn-l, Al = ABAB, Bl = BBBB
or A = ABAB
n n-1 n-1 n-1 n-1 n n-1 An-l An-l An-l, Al = ABAB, Bl = AAAA
30 or A = AABB
n nl nl nl nl with Bn = Bn-l Bn-1 Bn-1 Bn-1, Al = AABB and Bl = BBBB
20 ~ '~ 07 or A = ABAB
n n-1 n-1 n-1 n-1 a ec n n-1 n-1 n-1 n-1, A1 = ABAB, Bl = AAAA
or A = AABB
n n-1 n-1 n-1 n-1, with Bn = Bn-1 Bn-1 Bn-1 Bn-1, A1 = AABB and B1 = BBBB
5 or A = AABB
n n-1 n-1 n-1 n-1 with Bn = An-1 An-1 An-1 An-1, A1 = AABB and B1 = AAAA
The purpose of such a structure is in particular to lead to an incommensurability between the wave which must be directed and the geometric characteristics of the structure. It can be shown that this must lead to a localization of the energy inside even of the structure therefore to a total absorption.
According to a preferred embodiment, the material of the layer A (or B) has a composite structure comprising - a polymer based on polyethylene and an insulating polymer, proportion by weight of polyethylene being between 55% and 75%
- a charge of nickel powder whose particle size is included between 1 ~ m and 20 ~ m, with a volume charge rate of between 5%
and 35%.
The material of layer B (or A) is formed by said polymer based on polyethylene and insulating polymer, but free of fillers.
The following features constitute embodiments preferential:
Said particle size is between 3 ~ m and 20 ~ m, and particular-ment of the order of 5 ~ m.
Said charge rate is between 15% and 25%, and particularly around 19%.
The proportion of polyethylene in the polymer is around 65%.
According to another embodiment, the material of layer A (or B) has a composite structure comprising 30 - an insulating polymer comprising polyethylene, the proportion by weight of polyethylene being between 55 and 75%, - a charge of conductive polymers whose particle size is included between 0.5 ~ m and 100 ~ m and the rate between 5 and 90% in this polymer insulating, 35 - and by the fact that the complementary layer B (or A) is formed by 03 ~ 7 ~
said insulating polymer.
Said insulating polymer is chosen from EPDM, acrylonitrile butadiene styrene, the ethylene propylene copolymer monomer, the high pressure polyethylene, low pressure polyethylene, linear low pressure polyethylene, polyamide (nylon), polyacry-lonitrile, polybutylene terephthalate, polycarbonate, polyethylene, polyether ether ketone, polyethylene oxide, polyethylene terephthalate, polypropylene, oxide polyphenylene, polyphenylene sulfide, polystyrene, polyurethane.
Other features and advantages of the present invention will appear during the following description of examples of realization given by way of illustration but in no way limiting. In the attached drawing:
- Figure 1 shows variations of the reflection factor R of various structures according to the invention as a function of the frequency f in GHz.
- Figure 2 is similar to Figure 1, for the area between 8 and 12 GHz.
- Figure 3 is similar to Figure 2, for other structures according to the invention.
We start from a material allowing to realize a layer A and of which the composite structure includes:
- a polymer based on polyethylene and EPDM, the proportion (by weight) of polyethylene being 65%, - A char ~ e of nickel powder whose particle size is of the order of 5 ~ m, with a volume charge rate of around 24%.
A layer B is also produced comprising only the polymer cited above.
We realize a stack of order 1: A1 = ABA, that is to say comprising two layers A with an intermediate layer B. This stacking is deposited on a metal surface.
Table 1 lists the electrical and mechanics of these layers: ~ is the relative permittivity with respect to air, ~ relative permeability and ~ resistivity.
~ ~ 00 ~ 07 ~
, .................................... ~
BOARD
¦ ¦ A ¦ B ¦ A
H
1 ~ 1 3 1 3 1 3 ll H
I "1 1 1 1 11 1 11 ¦ ~ Qcm ¦ 0.05 ~ 0.05 I
I Thickness llm ¦ 750 ¦ 750 ¦ 750 H
It l 11 11 11 We also realize stacks:
- of order 2 A2 = AlBlAl with Bl = BBB
order 3 3 2 2 2 2 1 1 1 order 4 A4 3 3 3 3 2 2 2 - of order 5 A5 = A4B4A4 with B4 = B3B3B3-The total thickness of these stacks is always 2250 llm.
Figure 1 shows the variations of the reflection factor R on these different stacks Al, A2, A3, A4, A5 depending on the frequency f 25 in GHz.
Figure 2 has the same curves as Figure 1 but on an enlarged scale, in the range 8 to 12 GHz. We see the interest of A3 stacking in this frequency range especially for order 3. This stack having a thickness of 2.25 mm allows 30 an absorption between 90 and 99%, which is much better than that of Al. The choice of iteration order is therefore extremely important.
We perform the same type of stacks as before with A'l, A'2, A'3, A'4, A'5 such that the total thickness of the stack is 35 equal to 1800 ~ m.
~ 1 ~ 0307 ~
Figure 3 similar to Figure 2 shows the advantage of stacking of order of 3 in the range between 8 and 12 GHz.
Of course, the invention is not limited to the embodiments which have been described, in particular with regard to materials and 5 thicknesses of the layers of the stacks.
Claims (14)
A1 = f (A, B) ~~B1 = g (A, B) A2 = f (A1. B1) ~B2 = g(A1. B1) A n = f(A n-1, B n-1) ~B n = g(A n-1. B n-1) ledit empilement présentant ainsi une organisation fractale. 1. Structure to absorb electromagnetic waves, characterized by the fact that it comprises a stack of thin layers A n obtained from a layer A in one material chosen from semiconductor polymers and charged polymers, and a layer B of a chosen material among insulating polymers, polyethylene, polystyrene, polyvinyl chloride, stacking A n further having a sequence f such that:
A1 = f (A, B) ~~ B1 = g (A, B) A2 = f (A1. B1) ~ B2 = g (A1. B1) A n = f (A n-1, B n-1) ~ B n = g (A n-1. B n-1) said stack thus having a fractal organization.
A n = A n-1 B n-1 A n-1 avec B n = B n-1 B n-1 B n-1, A1 = ABA et B1 = BBB
ou ~A n = A n-1 B n-1 A n-1 avec ~B n = A n-1 A n-1 A n-1, A 1 = ABA et B 1 = AAA. 2. Structure for absorbing electromagnetic waves according to claim 1, characterized in that the said sequence f is such that:
A n = A n-1 B n-1 A n-1 with B n = B n-1 B n-1 B n-1, A1 = ABA and B1 = BBB
or ~ A n = A n-1 B n-1 A n-1 with ~ B n = A n-1 A n-1 A n-1, A 1 = ABA and B 1 = AAA.
A n = A n-1 B n-1, A n-1 B n-1 A n-1 avec B n = B n-1 B n-1 B n-1 B n-1 B n-1, A1 = ABABA, B1 = BBBBB
ou A n = A n-1 B n-1 A n-1 B n-1 A n-1 avec B n = A n-1 A n-1 A n-1 A n-1 A n-1, A1 = ABABA, B1 = AAAAA. 3. Structure for absorbing electromagnetic waves according to claim 1, characterized in that the said sequence f is such that:
A n = A n-1 B n-1, A n-1 B n-1 A n-1 with B n = B n-1 B n-1 B n-1 B n-1 B n-1, A1 = ABABA, B1 = BBBBB
or A n = A n-1 B n-1 A n-1 B n-1 A n-1 with B n = A n-1 A n-1 A n-1 A n-1 A n-1, A1 = ABABA, B1 = AAAAA.
A n = A n-1 B n-1 A n-1 B n-1 avec B n = B n-1 B n-1 B n-1 B n-1, A1 = ABAB, B1 = BBBB
ou A n = A n-1 B n-1 A n-1 B n-1 avec B n = A n-1 A n-1 A n-1 A n-1, A1 = ABAB, B1 = AAAA. 4. Structure to absorb electromagnetic waves according to claim l, characterized in that said sequence f is such that:
A n = A n-1 B n-1 A n-1 B n-1 with B n = B n-1 B n-1 B n-1 B n-1, A1 = ABAB, B1 = BBBB
or A n = A n-1 B n-1 A n-1 B n-1 with B n = A n-1 A n-1 A n-1 A n-1, A1 = ABAB, B1 = AAAA.
A n = A n-1 A n-1 B n-1 B n-1 avec B n = B n-1 B n-1 B n-1 B n-1, A1 = AABB, B1 = BBBB
ou A n = A n-1 B n-1 A n-1 B n-1 avec B n = A n-1 A n-1 A n-1 A n-1, A1 = ABAB, B1 = AAAA. 5. Structure to absorb electromagnetic waves according to claim 1, characterized in that the said sequence f is such that:
A n = A n-1 A n-1 B n-1 B n-1 with B n = B n-1 B n-1 B n-1 B n-1, A1 = AABB, B1 = BBBB
or A n = A n-1 B n-1 A n-1 B n-1 with B n = A n-1 A n-1 A n-1 A n-1, A1 = ABAB, B1 = AAAA.
A n = A n-1 A n-1 B n-1 B n-1 avec B n = B n-1 B n-1 B n-1 B n-1, A1 = AABB, B1 = BBBB
ou A n = A n-1 A n-1 B n-1 B n-1 avec B n = A n-1 A n-1 A n-1 A n-1, A1 = AABB, B1 = AAAA. 6. Structure for absorbing electromagnetic waves according to claim 1, characterized in that the said sequence f is such that:
A n = A n-1 A n-1 B n-1 B n-1 with B n = B n-1 B n-1 B n-1 B n-1, A1 = AABB, B1 = BBBB
or A n = A n-1 A n-1 B n-1 B n-1 with B n = A n-1 A n-1 A n-1 A n-1, A1 = AABB, B1 = AAAA.
- un polymère à base de polyéthylène et de polymère isolant, le polyéthylène constituant une proportion en poids comprise entre 55% et 75%, - une charge de poudre de nickel ayant une granulométrie comprise entre 1 µm et 20 µm, avec un taux de charges en volume compris entre 5% et 35%, et par le fait que l'autre couche B ou A est formée par ledit polymère à base de polyéthylène et de polymère isolant. 7. Structure for absorbing electromagnetic waves according to one of claims 1 to 6, characterized in that that layer A or B has a composite structure including:
- a polymer based on polyethylene and insulating polymer, polyethylene constituting a proportion by weight between 55% and 75%, - a charge of nickel powder having a particle size between 1 µm and 20 µm, with a charge rate of volume between 5% and 35%, and by the fact that the other layer B or A is formed by said polymer based on polyethylene and insulating polymer.
- un polymère isolant comportant du polyéthylène, le polyéthylène constituant une proportion en poids comprise entre 55 et 75%, - une charge de polymères conducteurs ayant une granulométrie comprise entre 0,5 µm et 100 µm et un taux entre 5 et 90% dans le polymère isolant, - et par le fait que l'autre couche B ou A est formée par ledit polymère isolant. 13. Structure to absorb electromagnetic waves according to any one of claims 1 to 6, characterized by the fact that layer A or B has a structure composite comprising:
- an insulating polymer comprising polyethylene, polyethylene constituting a proportion by weight included between 55 and 75%, - a charge of conductive polymers having a particle size between 0.5 µm and 100 µm and a rate between 5 and 90% in the insulating polymer, - and by the fact that the other layer B or A is formed by said insulating polymer.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8814940 | 1988-11-17 | ||
FR8814940A FR2737347B1 (en) | 1988-11-17 | 1988-11-17 | STRUCTURE FOR THE ABSORPTION OF ELECTROMAGNETIC WAVES |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2003074A1 CA2003074A1 (en) | 1996-10-11 |
CA2003074C true CA2003074C (en) | 2001-01-09 |
Family
ID=9371931
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002003074A Expired - Fee Related CA2003074C (en) | 1988-11-17 | 1989-11-16 | Structure for the absorption of electromagnetic waves |
Country Status (8)
Country | Link |
---|---|
BE (1) | BE1010512A4 (en) |
CA (1) | CA2003074C (en) |
DE (1) | DE3936195C2 (en) |
FR (1) | FR2737347B1 (en) |
GB (1) | GB2310541B (en) |
IT (1) | IT1267133B1 (en) |
NL (1) | NL8902827A (en) |
NO (1) | NO306918B1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
RU2249862C1 (en) * | 2004-07-02 | 2005-04-10 | Общество с ограниченной ответственностью "НПО"АЙРЭС Технолоджис" | Device for structuring electromagnetic field |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2996709A (en) * | 1945-04-27 | 1961-08-15 | Du Pont | Flexible electromagnetic radiationabsorptive article |
US3349397A (en) * | 1966-02-03 | 1967-10-24 | North American Aviation Inc | Flexible radiation attenuator |
US3721982A (en) * | 1970-11-10 | 1973-03-20 | Gruenzweig & Hartmann | Absorber for electromagnetic radiation |
SE8007075L (en) * | 1979-10-31 | 1981-05-01 | Illinois Tool Works | SKERMNING |
US4353069A (en) * | 1980-09-10 | 1982-10-05 | Handel Peter H | Absorptive coating for the reduction of the reflective cross section of metallic surfaces and control capabilities therefor |
DE3307066A1 (en) * | 1983-03-01 | 1984-09-13 | Dornier Gmbh, 7990 Friedrichshafen | MULTILAYER FIBER COMPOSITE |
US4680236A (en) * | 1986-02-18 | 1987-07-14 | The Bf Goodrich Company | Electrodeless heterogeneous polypyrrole composite |
GB2192756A (en) * | 1986-07-07 | 1988-01-20 | Hoybond Limited | Energy absorbing coatings and their use in camouflage |
-
1988
- 1988-11-17 FR FR8814940A patent/FR2737347B1/en not_active Expired - Fee Related
-
1989
- 1989-10-31 DE DE3936195A patent/DE3936195C2/en not_active Expired - Fee Related
- 1989-11-03 GB GB8924797A patent/GB2310541B/en not_active Expired - Fee Related
- 1989-11-07 IT IT06795589A patent/IT1267133B1/en active IP Right Grant
- 1989-11-08 NO NO894440A patent/NO306918B1/en not_active IP Right Cessation
- 1989-11-15 NL NL8902827A patent/NL8902827A/en active Search and Examination
- 1989-11-16 CA CA002003074A patent/CA2003074C/en not_active Expired - Fee Related
- 1989-11-16 BE BE8901211A patent/BE1010512A4/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
IT8967955A0 (en) | 1989-11-07 |
CA2003074A1 (en) | 1996-10-11 |
IT8967955A1 (en) | 1991-05-07 |
NO894440L (en) | 1996-08-13 |
DE3936195A1 (en) | 1997-03-06 |
GB2310541A (en) | 1997-08-27 |
DE3936195C2 (en) | 1999-02-18 |
NL8902827A (en) | 1997-08-01 |
FR2737347A1 (en) | 1997-01-31 |
BE1010512A4 (en) | 1998-10-06 |
GB8924797D0 (en) | 1996-12-18 |
NO306918B1 (en) | 2000-01-10 |
IT1267133B1 (en) | 1997-01-24 |
GB2310541B (en) | 1998-01-07 |
FR2737347B1 (en) | 1997-12-19 |
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