CN1128485C - Electromagnetic wave absorption panels and materials for same - Google Patents

Electromagnetic wave absorption panels and materials for same Download PDF

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Publication number
CN1128485C
CN1128485C CN98800025A CN98800025A CN1128485C CN 1128485 C CN1128485 C CN 1128485C CN 98800025 A CN98800025 A CN 98800025A CN 98800025 A CN98800025 A CN 98800025A CN 1128485 C CN1128485 C CN 1128485C
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China
Prior art keywords
layer
ferrite
electromagnetic wave
baffle
electro
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CN98800025A
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CN1216166A (en
Inventor
V·琼斯
木村健一
C·A·帕兹德阿若久
清川博
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Fujita Corp
Symetrix Corp
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Fujita Corp
Symetrix Corp
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Priority claimed from US08/782,938 external-priority patent/US5853889A/en
Priority claimed from US08/782,934 external-priority patent/US6037046A/en
Application filed by Fujita Corp, Symetrix Corp filed Critical Fujita Corp
Publication of CN1216166A publication Critical patent/CN1216166A/en
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/92—Protection against other undesired influences or dangers
    • 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
    • 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
    • H01Q17/004—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems using non-directional dissipative particles, e.g. ferrite powders
    • 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
    • H01Q17/007—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with means for controlling the absorption
    • 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
    • H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape

Abstract

An electromagnetic wave absorption panel (100) for use in building construction includes an absorber layer (106) that utilizes novel materials such as layered superlattice materials, garnets, magnetoresistive materials, conducting oxides, such as LSM, magnetoplumbites, signet magnetics, Fe3O4, Ni0.4Zn0.6Fe2O4, and polymer composites of the above materials. The absorber layer is preferably a multi-component structure such as a layer of a ferrite (114) combined with one or more of the above materials. The invention also includes: a multi-component absorber element (106) having an effective real part of the permitivity, ELEMENT 'eff, and an effective real part of the permeability, mu 'eff, such that ( ELEMENT 'eff mu 'eff)<1/2> SIMILAR 1/f over said range of frequencies, where f is the frequency of the incident wave; and a multi-component absorber element (106) having an effective real part of the permitivity, ELEMENT 'eff, that decreases with frequency.

Description

Electro-magnetic wave absorption plate and manufactured materials thereof
The background of invention
1. FIELD OF THE INVENTION
The present invention relates to be used for building the sheet material of the building that can absorb electromagnetic wave (the particularly electromagnetic wave in radio signal transmission, TV signal transmission and microwave frequency range).More specifically to the sheet material that makes by two or more different materials, as composite material and multi-layer sheet.
2. the elaboration of problem
Recognize that for many years reflection electromagnetic wave can have problems on building or other works, electrostatic interference and noise that ghost image of accepting as TV and radio are accepted.In densely populated high-tech society, as this very big problem especially of the U.S., Europe and Japanese big city.For example, must there be radio and television electromagnetic wave Impact Report in the big city of Japan before building building, and the building that building laws also may require to build up should avoid reflecting the electromagnetic wave of radio, TV and some microwave frequency range (being 80-2400MHz).Electromagnetic wave sees through construction material and also can cause privacy problem in some cases.In view of these reasons, the construction material to the energy absorption of electromagnetic radiation had carried out extensive studies already.For example, can be referring to Investigetion onOblique Incident Characteristics of Ferrite Absorbing Panels For TV GhostSuppression, Hironobu Ito et al. Japan Broadcasting Corporation et al (about 1994).The electro-magnetic wave absorption plate that is used for building generally comprises the supporting course of concrete or other basic building materials, be generally the reflector of wire netting or other electric conducting material, be generally ferritic absorbed layer and be used to the skin (patch block as silicate) of protecting absorbed layer to exempt from environmental impact.Other material as absorbed layer comprises the electric conducting material (as carbon fiber) that is blended in the resin.
Because nearly all material all has the characteristic absorption frequency of absorption of electromagnetic radiation, therefore in some narrow frequency ranges, can relatively easily find the material of absorption of electromagnetic radiation.For example, ferritic absworption peak is about 200-400MHz.But be difficult to (if not impossible words) find can thousands of megahertzes or even the wide frequency range of only hundreds of megahertzes absorb electromagnetic material.Therefore once attempted to use the sandwich construction of the combined material that comprises ferrite, the conductive fiber in resin and other analog structure thing as electromagnetic wave absorb.
Known use quarter wave plate is as electromagnetic wave absorb.In this absorber, be the front that the material of 1/4 wavelength places 100% reflecting material (as metal level) with thickness.Up to now this principle of absorption also is not used to make the building baffle, because the electromagnetic wavelength of television frequency scope has several meters long.Therefore, several meters long this absorber is too thick concerning building.
The most successful material that is used for the electro-magnetic wave absorption plate is a ferrite, and it is heavier relatively, and thickness must just can come into force up to Centimeter Level, and softer relatively, thereby needs other building materials layer (as patch block) to exempt from environmental impact to protect it.Therefore, electro-magnetic wave absorption plate bulk known in the art is big, and Heavy Weight makes to be difficult to the building cost height be widely used for whole building building, and can not to absorb the electromagnetic wave that is present in all frequency ranges in the big city usually, and perhaps two kinds of problems have.In addition, conventional ferrite absorption frequency is 200-400MHz, and VHF television frequency scope is about 100-250MHz, UHF television frequency scope approximately from 450MHz to up to about 800MHz.Therefore, press for a kind of gently relatively and approach, the while can absorb wide frequency ranges (comprising up to about 800MHz) absorption of electromagnetic wave plate.
Existing electro-magnetic wave absorption plate generally is only applicable to the electromagnetic frequency range of TV, and this electromagnetic wave is owing to the problem that reflection produces is the most general.But, can cause serious consequence in other specific regional reflection of electromagnetic wave problem, for example radio LAN system (its meeting is obliterated data owing to reflect) and airport radio control system (definition of its signal is related to existence and dead).Therefore press for a kind of can strong absorption absorption of electromagnetic wave plate in the frequency range of these special purposes.
Find that in practice because the electromagnetic wave source of approaching narrow frequency range, therefore many buildings place only has negative influence to the electromagnetic environment of narrow frequency range, this narrow frequency range is difficult to predict before learning the building construction place.Therefore, it is very useful easily being adjusted to the baffle of characteristic frequency and the manufacture method of this baffle.
The general introduction of invention
The present invention solves the problems referred to above by the multicomponent absorber is provided, and according to the electromagnetic environment problem that is determined by specific building place, described absorber can be adjusted to the covering wide frequency range, or is adjusted to specific frequency range is had big absorbability.Described adjusting can be by selecting the concrete material in the multiple layer combination material, the thickness of selecting concrete material, change multiple layer combination material middle level in the composite material or composite material thickness, change in the composite material each components contents and be used in combination said method and realize.
The invention provides special combination of materials, and use this combination to solve the problem of wide region, or regulate this combination to solve special problem.For example, the invention provides a kind of high dielectric constant material and ferritic combination, it is the efficient absorption body of medium range television frequency, and can be by selecting concrete material and being adjusted to specific frequency range by the thickness that changes each component layers.In another example, the combination of ferroelectric layer, ferrite layer, polymeric layer and reflective metal layer has excellent absorption to the electromagnetic wave of whole television frequency scope.In another example, the combination of first ferrite layer and second ferrite layer can be adjusted to specific frequency, when the frequency range that produces reflection loss changed, the quantitative changeization of reflection loss was very little.
The invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member layer, described absorber element comprises ground floor, the second layer and the 3rd layer, compare with the described second layer, the incidence point of the more close electromagnetic wave of described ground floor on described baffle, the distance of the described electromagnetic wave incidence point of described the 3rd leafing is farther, described ground floor comprises high dielectric constant material, the described second layer comprises ferrite, and described the 3rd layer comprises advanced low-k materials.Be preferably, described advanced low-k materials is a polymer, and high dielectric constant material is a ferroelectric material.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member, described absorber element comprises the ground floor and the second layer, compare with the described second layer, more near the incidence point of electromagnetic wave on described baffle, described ground floor comprises ferrite to described ground floor, and the described second layer comprises high dielectric constant material.Be preferably, described ferrite is a nickel-zinc ferrite, and described high dielectric constant material is BST.Described absorber element preferably also comprises: at the 3rd layer between the described ground floor and the second layer and between described the 3rd layer and the second layer the 4th layer, described the 3rd layer comprises polymer; Described the 4th layer comprises LSM.Be preferably, described absorber element also comprises to be compared with ground floor from farther the 3rd layer of electromagnetic incidence point, and described the 3rd layer comprises advanced low-k materials.Be preferably, the 3rd layer between the ground floor and the second layer, and described reflecting plate also comprises with the absorber element and comparing from the farther conduction reflecting element of electromagnetic wave incidence point.Be preferably, the absorber element also comprises the 4th layer that contains dielectric material.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member, described absorber element comprises the ground floor and the second layer, compare with described ground floor, the described second layer is farther from the incidence point of electromagnetic wave on described baffle, and described ground floor comprises ferroelectric material, and the described second layer comprises ferrite.Be preferably, described absorber element also comprises to be compared with the described second layer from farther the 3rd layer of electromagnetic incidence point.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member, described absorber element comprises the ground floor and the second layer, compare with described ground floor, the described second layer is farther from the incidence point of electromagnetic wave on described baffle, and described ground floor comprises ferrite, and the described second layer comprises ferroelectric material.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member, described absorber element comprise the ground floor that contains polymer and contain the second layer of the higher material of the described polymer of permittivity ratio.Be preferably, compare with described ground floor, the described second layer is farther from the incidence point of electromagnetic wave on described baffle.Perhaps, compare with the described second layer, described ground floor is farther from the incidence point of electromagnetic wave on described baffle.Be preferably, the described second layer contains ferrite and n group absorber element is arranged, and each is organized the absorber element and comprises one deck ground floor and one deck second layer, and n is the integer of 2-100.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member, by the reflecting element of this supporting member supporting with by the absorber element of this supporting member supporting, compare with described reflecting element, the incidence point of the more close electromagnetic wave of described absorber element on baffle, described absorber element comprises the second layer that contains ferritic ground floor and contain advanced low-k materials, compare with described ground floor, the described second layer is farther from the incidence point of electromagnetic wave on described baffle.Be preferably, n group absorber element is arranged, each is organized the absorber element and comprises one deck ground floor and one deck second layer, and n is the integer of 2-100.
The present invention also provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is supported by this supporting member, described absorber element comprises the ground floor that contains high dielectric constant material, contain the second layer of magnetic permeability imaginary part more than or equal to the material of magnetic permeability real part, and contain the 3rd layer of advanced low-k materials, compare the incidence point of described the 3rd leafing electromagnetic wave on baffle with ground floor farther, and the second layer is between ground floor and the 3rd layer.Be preferably, the second layer contains ferrite, and reflecting plate also comprises with the absorber element and comparing from the farther conduction reflecting element of the incidence point of electromagnetic wave on baffle.Be preferably, described the 3rd layer contains polymer, and described ground floor contains and is selected from ABO 3The material of the superlattice material of type perovskite and layering.
In addition, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle can absorb electromagnetic wave over a range of frequencies effectively, and it comprises that the effective real part of permittivity is ε ' EffWith the effective real part of magnetic permeability be μ ' EffMulticomponent absorber element, in described frequency range (ε ' Effμ ' Eff) 1/2～1/f, wherein f is the frequency of incident electromagnetic wave.
Another aspect of the present invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, and this baffle can absorb electromagnetic wave over a range of frequencies effectively, and this baffle comprises the effective real part ε ' of permittivity EffMulticomponent absorber element with frequency decline.
The present invention never considers to be used for high dielectric constant material, ferroelectric, conductive oxide, magneto-plumbite type, garnet and video (signet) magnetic material of this baffle also by providing the electro-magnetic wave absorption plate to solve the problems referred to above before the material of described baffle for example comprises.These materials can be used in combination with the ferrite that was used for the electro-magnetic wave absorption plate in the past, and it (is Ni that the present invention also provides a kind of new nickel-zinc ferrite 0.4Zn 0.6Fe 2O 4), it is specially adapted to the electro-magnetic wave absorption plate.
The invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is bearing on this supporting member, described absorber element comprises high dielectric constant material.Be preferably, this absorber element also comprises ferrite and polymer.Be preferably, described high dielectric constant material is to be selected from ABO 3The material of the superlattice material of type perovskite, layering, conductive oxide and video magnetic material.Be preferably, described high dielectric constant material is to be selected from BST, LSM and Z * BaTiO 3+ (100%-Z) * BiFeO 3Material, 100%＞Z＞0% wherein.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, this baffle comprises: building supporting member and the absorber element that is bearing on this supporting member, described absorber element comprises ferroelectric material.Be preferably, this absorber element also comprises ferrite and polymer.Be preferably, described ferroelectric is selected from ABO 3The superlattice material of type perovskite and layering.Be preferably, this ferroelectric is to be selected from barium titanate, strontium bismuth tantalate, niobic acid strontium bismuth, strontium bismuth titanate, strontium zirconate bismuth and solid solution thereof.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, described baffle comprises: building supporting member and the absorber element that is bearing on the described supporting member, described absorber element comprises the composite material of polymer and second kind of material, and described second kind of material is to be selected from high dielectric constant material, ferroelectric, garnet, magneto-plumbite type and video magnetic material.Be preferably, described second kind of material is the material that is selected from nickel-zinc ferrite, BST, LSM, yttrium-iron garnet, strontium bismuth tantalate, niobic acid strontium bismuth, strontium bismuth titanate, strontium zirconate bismuth and solid solution thereof.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, described baffle comprises: building supporting member and the absorber element that is bearing on the described supporting member, described absorber element comprises garnet.Be preferably, described garnet is yttrium-iron garnet.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, described baffle comprises: building supporting member and the absorber element that is bearing on the described supporting member, described absorber element comprises magnetoresistance material.Be preferably, this magnetoresistance material is to be selected from La 0.67Sr 0.33MnO 3, La xCa (1-x)MnO 3And La xPb (1-x)MnO 3Material, 0＜x＜1 wherein.
On the other hand, the invention provides a kind of electro-magnetic wave absorption plate that is used for construction of buildings, described baffle comprises: building supporting member and the absorber element that is bearing on the described supporting member, described absorber element is Ni 0.4Zn 0.6Fe 2O 4
The baffle that these new materials make is lighter than existing baffle, and volume is littler, and can absorb the interior electromagnetic wave of wide frequency ranges.In addition, the operation principle of analyzing new material can further be understood the absorption of electromagnetic wave process.
The present invention not only provides new electro-magnetic wave absorption plate multiple component structure, this structure is lighter than being used to absorb electromagnetic existing structure in the building, volume is littler and absorb the more electromagnetic wave of wide frequency ranges, and the research of this structure caused that absorption of electromagnetic wave principle (as in baffle medium dielectric constant microwave medium role) is had darker understanding, also formed the method for designing of baffle: develop a kind of structure earlier, big activation absorbs electromagnetic wave in the zone that requires to absorb for it, the composition of regulating absorber subsequently makes dielectric constant and other parameter can approach quarter wave plate, and the thickness of adjusting material makes it to cover the frequency range of requirement with the migration absorption bands.Following description with reference to accompanying drawing will further specify many other features, objects and advantages of the present invention.
The accompanying drawing summary
Fig. 1 is the schematic diagram of the electro-magnetic wave absorption plate of the present invention clipped of part;
Fig. 2 is the profile of electro-magnetic wave absorption plate of the present invention along the 2-2 of Fig. 1;
Fig. 3 is the profile of better example of the electromagnetic wave absorbing layer of Fig. 1 baffle;
Fig. 4 is the profile of another better example of the electromagnetic wave absorbing layer of Fig. 1 baffle;
Fig. 5 is the reflection loss-frequency curve of three kinds of different high-ks of the present invention/ferrite electro-magnetic wave absorption patch block;
Fig. 6 is the reflection loss-frequency curve of the solid solution of six kinds of different nickel-zinc ferrites;
Fig. 7 is ferrite Ni 0.4Zn 0.6Fe 2O 4The relation of the real part of permittivity and imaginary part and frequency;
Fig. 8 is ferrite Ni 0.4Zn 0.6Fe 2O 4The relation of the real part of magnetic permeability and imaginary part and frequency;
Fig. 9-the 15th, the profile of other better examples of the electromagnetic wave absorbing layer of Fig. 1 baffle;
Figure 16 is the reflection loss-frequency curve of five kinds of different-thickness combinations of the multilayer electromagnetic wave absorb made by one deck Mn ferrite and one deck nickel-zinc ferrite solid solution.
Figure 17 be computer simulation comprise 1mm 50/50BaTiO 3+ BaFeO 3Solid solution, 5mmNi 0.4Zn 0.6Fe 2O 4And 5mm Teflon TMThe reflection loss-frequency curve of baffle;
Figure 18 has 5mm Ni comprising of computer simulation 0.4Zn 0.6Fe 2O 4, 4mm Merlon and 1mm70/30BST the reflection loss-frequency curve of baffle of ferrite/polymer/high-k absorbed layer;
Figure 19 has 13mm 50% Merlon and 50% (BaTiO comprising of computer simulation 3+ 4BiFeO 3) the reflection loss-frequency curve of baffle of polymer-ceramic composite absorption layer;
Figure 20 has Ni comprising of computer simulation 0.4Zn 0.6Fe 2O 4As ferrite, BST reflection loss-frequency curve as dielectric 182 and unreflected ferrite/high-k electromagnetic wave absorb;
Figure 21-the 24th, the profile of other better examples of the electromagnetic wave absorbing layer of Fig. 1 baffle;
Figure 25 is the reflection loss-frequency curve of the ferrite/polymer/LSM/ high-k absorber of all thickness of computer simulation;
Figure 26 is the reflection loss-frequency curve of multilayer ferrite/polymer absorber of all thickness of computer simulation;
Figure 27 is the reflection loss-frequency curve of various ferrites/combination of polymers thickness in the absorber with 50 groups of ferrite/polymeric layers of computer simulation;
Figure 28 is a flow chart of making polymer-ceramic composites method of the present invention;
Figure 29 is a flow chart of making ceramic material method of the present invention;
Figure 30 is the profile of another better example of the electromagnetic wave absorbing layer of Fig. 1 baffle.
The detailed description of better example
Fig. 1 and Fig. 2 are the schematic diagrames of electro-magnetic wave absorption plate of the present invention.Fig. 1 is the perspective view that part is clipped, and Fig. 2 is a profile.At first, should understand the accompanying drawing that Fig. 1, Fig. 2 and other be used to describe absorber 106 sections of the present invention is not the picture of describing actual absorption plate or absorber, but with actual picture mutually specific energy be illustrated more clearly in rough schematic view of the present invention.For example, some layer is compared too thin with other layer, if so that describe each layer with correct relative thickness, then many accompanying drawings can be difficult to be drawn on the sheet-fed too greatly.Baffle 100 comprises four primary elements: supporting member 102, reflecting element 104, absorber element 106 and outer protection component 108.Be preferably, each element 102,104,106 and 108 includes layer of material, is parallel to each other substantially between described layers of material.Supporting member 102 is made by construction material (as concrete).Reflector 104 is layer of conductive material (as metal) normally.In example preferably, it is one deck iron net or grille 104 normally, and it is embedded in the concrete 102 and also plays reinforced concrete as known in the concrete field.In general, the degree of depth imbedded in concrete 102 of net 104 is the 1-5 inch.Since the electromagnetic wavelength that will absorb be one meter to the hundreds of meters orders of magnitude, so they " feel " this net be substantially monoblock and be reflected.Reflector element 106 just schematically is presented among Fig. 1 and Fig. 2.The better example of this layer 106 is described in detail in down.By describing below as can be known, each example of absorber 106 comprises a plurality of components, and it can contain two kinds of different material components (as the polymer in the polymer-ceramic composites and second kind of material), perhaps contains the layer of two-layer or multiple layers of different materials.From the above mentioned, should understand herein term " multicomponent " and not comprise single compound of planting, even this compound contains multiple element.Protection component 108 is generally made by routine building material (as siliceous patch block), and it has decoration function and anti-Weather effect simultaneously concurrently.A key character of the present invention is in some instances, and protection patch block element 108 is chosen wantonly, and in other words, it is the part of absorber element 106.That is to say that some absorbent material of the present invention (as high dielectric constant material (referring to following)) also is ceramic material or other hardened material with high anti-Weather.Reflecting element 104 is also chosen wantonly.In some cases, reflecting element 104 can be sneaked into thickness is enough to stop in the supporting member 102 that all electromagnetic radiation penetrate.In some cases, when the intensity of absorber element 106 was enough to support the wall of its participation or other works, supporting member 102 can be identical with this absorber element 106.Although example relates generally to concrete or other building of reflecting element 104 as an integral part preferably, in some applications,, can not need reflecting element if require reflection is remained on hour.That is to say, in some cases, not produce reflection and just can solve the ghost image problem.Except as otherwise noted, otherwise all have reflecting element 104 in the example that is described below.Because the present invention relates generally to the material and the structure of absorber element 106, therefore absorber element 106 will mainly be described at the lower part of this paper.Fig. 2 and below in each example of absorber element 106, electromagnetic radiation 110 is from the left side incident of accompanying drawing.This is important, because be important from the ordering of the multilayer absorbing material of incidence point 109 beginning of electromagnetic radiation 110 for producing best absorbability.
Being difficult to build and test absorber plate 100 is the biggest obstacles that make progress in the art.Breadboard 100 volumes are big, are difficult for manufacturing various structure.In addition, be difficult to make the experimental rig that to test sample satisfactorily.The present invention has overcome above-mentioned difficulties by the computer architecture of setting up the complexity that can simulate various baffle 100 structures.Set up the example of many baffles 100 and the result of itself and computer simulation system has been compared to help to improve this simulated system.In the following description, the data that record unless stated otherwise are from the computer simulation system, otherwise data provide by the sample of reality.
Fig. 3 is the profile of the better example 106A of absorber element of the present invention.In the actual manufacturing of absorber 106 and test, for the example 106A of Fig. 3 and the example of following other actual manufacturing, make absorber as follows, and be fixed on the metal support in the coaxial anchor clamps.That is to say, because the significant difficulties in the test does not comprise supporting mass 102 and outer patch block 109 when therefore testing.But because electromagnetic wave 100% is reflected from the conductive metal layer, and test shows that outer patch block 109 can obviously not influence absorber, so the baffle 100 of the very approaching reality of experimental result described herein.Absorber element 106A comprises material 112, and it is dielectric material preferably, but also can be the listed any material of table 1.In the example of Fig. 3, although the dielectric material of this example 112 high dielectric constant material preferably also can use the listed any dielectric material of table 1.Layer 114 is ferrites.It can be any ferrite, although better be nickel-zinc ferrite, copper zinc ferrite or cobalt zinc ferrite oxysome, preferably Ni 0.4Zn 0.6Fe 2O 4Dielectric material 112 preferably obviously is thinner than ferrite 114, especially when it is high dielectric constant material.When material 112 was high dielectric constant material, it was generally than ferrite 114 thin 2-10 times, preferably thin approximately 3-6 times.In Fig. 3 example, material 112 is the outer surface of more close baffle 100 away from reflector 104.Find that also the electro-magnetic wave absorption plate is starved of high dielectric constant material, no matter and its position with respect to other absorbent material.In this article, term " high-k " refers to that dielectric constant is 20 or higher, is preferably 50 or higher, and term " advanced low-k materials " refers to that dielectric constant is 10 or lower material.Be preferably, advanced low-k materials is silex glass or plastics, as Teflon TM, Merlon, polyethylene or other polymer.Also can use aluminium oxide.High dielectric material 112 can be to be ferroelectric metal oxide under some temperature, although it may not be a ferroelectric in room temperature.The example that is applicable to the high dielectric constant material of electro-magnetic wave absorption plate has ABO 3The type perovskite comprises the superlattice material of dielectric material and ferroelectric such as barium strontium (BST), barium titanate and layering also comprising it being dielectric material and ferroelectric material such as strontium bismuth tantalate, strontium bismuth tantalum niobate and niobic acid barium bismuth simultaneously.ABO 3The type perovskite is described in Franco Jona and G.Shirane, Ferroelectric Crystals, Dover Publications, New York, pp108 et seq.The superstructure of layering (superlattice) material is described in the United States Patent (USP) 5,519,234 of on May 21st, 1996 bulletin, can comprise conductive oxide such as La with stacked other material of ferrite 114 1-xSr xMnO 3(LSM) and Fe 3O 4Magnetoresistance material comprises the LSM of some proportioning, as La 0.67Sr 0.33MnO 3And La xCa (1-x)MnO 3And La xPb (1-x)MnO 3The video magnetic material is as BaTiO 3+ BiFeO 3Magneto-plumbite type is as BaO6Fe 2O 3Garnet such as yttrium-iron garnet (3Y 2O 35Fe 2O 4Or Y 6Fe 10O 24) etc.
The various types of materials that can be used in all other examples of Fig. 3 example and the present invention are listed in table 1.Should understand listed characteristic and summarize, the concrete material of given type is had deviation.The round dot of attention in formula separates the two parts that may exist in varing proportions in the material; For example, BaO6Fe 2O 3Be meant 1 BaO of unit and 6 Fe of unit 2O 3Mixture, it is the conventional method for expressing of magneto-plumbite type and this material of video magnetic material for example.Table 1 is listed " composite material " as one type dielectric material (dielectric).Many these class composite materials will be described below.In this article, term " composite material " is meant the material that the homogeneous mixture (being evenly distributed in the whole polymer as ceramic powder) by at least two kinds of different materials makes.
Table 1
The material classification This classification examples of material The general character of this classification material
Conductive oxide LSM High ε ', low ε ", very low μ
Magnetoresistance material La 0.67Sr 0.33MnO 3 La xCa (1-x)MnO 3 La xPb (1-x)MnO 3 Medium ε ', high ε "
The dielectric material that mixes Silex glass, Al 2O 3 Be low to moderate medium ε ', low ε ", μ=1
ABO 3The type dielectric material BST High ε ', low ε ", μ=1
The superlattice material dielectric material of layering BaBi 2Nb 2O 9 High ε ', low ε ", μ=1
Polymer dielectric material for electrical Merlon, Teflon, polyethylene kind Low ε ', low ε ", μ=1
ABO 3The type ferroelectric BaTiO 3 High ε ', medium ε ", μ=1
The superlattice material ferroelectric of layering SrBi 2Ta 2O 9 High ε ', medium ε ", μ=1
Magneto-plumbite type BaO·6Fe 2O 3 Medium ε ', high ε ", low μ ＂
The video magnetic material BaTiO 3+BiFeO 3 BaTiO 3+BaFeO 3 BaO·3BaTiO 3·3Fe 2O 3 High ε ', medium ε ", low μ (＜1Ghz) medium μ (＞1GHz)
The ceramic body that mixes (general dielectric material) SrTa 2O 6 High ε ', low ε ", μ=1
Fig. 5 is the absorbent properties that absorbed patch block 106A by three kinds of different multilayers that high dielectric constant material and ferrite make.Each root curve 117,118 and 119 expressions are the reflection loss of unit with the decibel and are functional relation between the frequency of unit with GHz.Reflection loss is the amount of electromagnetic radiation and the waste that obtains from the amount of electromagnetic radiation of 109 lateral reflections that relatively is incident on 109 sides.All curves all record in room temperature.Curve 117 is the reflection loss of patch block 106A and the functional relation of frequency, and its middle level 112 is 1mm tantalic acid strontium (SrTa 2O 6); Layer 114 is 5mm nickel-zinc ferrite (Ni 0.4Zn 0.6Fe 2O 4), it is two kinds of ferrite NiFe 2o 4And ZnFe 2O 4Solid solution.Curve 118 is the reflection loss of patch block 106A and the functional relation of frequency, and its middle level 112 is 1mm tantalic acid strontium (SrTa 2O 6); Layer 114 is 4mm nickel-zinc ferrite (Ni 0.4Zn 0.6Fe 2O 4).Curve 119 is the reflection loss of patch block 106A and the functional relation of frequency, and its middle level 112 is 1mm tantalic acid strontium (SrTa 2O 6); Layer 114 is 5mm Mn ferrite (MnFe 2O 4).SrTa 2O 6Dielectric constant be about 90, and Ni 0.4Zn 0.6Fe 2O 4Dielectric constant be about 10 (see figure 7)s.In general, in electro-magnetic wave absorption plate field, think that the material with 20db or higher incident wave reflection loss is good absorber.The absorption of 20db is the big decay that must be enough to generation notable difference in the influence of building electromagnetic wave, because this is the decay that present electronic circuit is enough to the undesirable reflection of elimination.The absorption of 1mm/5mm tantalic acid strontium/Ni Zn ferrimagnet body curve 119 makes it to become acceptable absorber in about 0.1-0.3GHz (100Mhz-300MHz) scope.Shown in curve 118, the thickness minimizing 1mm with nickel-zinc ferrite makes patch block become good absorber at about 0.25-0.5GHz.Make ferrite into Mn ferrite, can make patch block in about 0.5-0.65GHz scope, become good absorber.This need be desirable selection at the systemic building of this scope for thinking in the electromagnetic wave Impact Report.General rice says that ferrite has low DIELECTRIC CONSTANT ', low or medium magnetic permeability imaginary part ε ", low magnetic permeability real part μ ', and high magnetic permeability imaginary part μ ".
From the obtainable most important information of Fig. 5 curve may be the strong influence that absworption peak frequency and absworption peak width are subjected to the minor variations and the changes in material of thickness.Therefore, can design adjusting high-k/ferrite absorber, make it to cover whole television frequency scope, promptly by about 0.1GHz-8GHz, in the scope of about 200 megahertzes of arbitrary position almost.
The electro-magnetic wave absorption body member 106B that contains two or more ferritic solid solution is shown in Fig. 4.Find that this solid solution itself is better than single ferrite of planting, especially when specific frequency range be key the time.Absworption peak frequency and absworption peak width height depend on the thickness of various ferritic ratios and absorber in the solid solution.This can be referring to Fig. 6, and Fig. 6 shows the absorbent properties of six kinds of different nickel-zinc ferrite solid solution.The chemical formula of solid solution and the thickness of various patch blocks are listed in table 2.
Table 2
The curve numbering Solid solution Thickness
131 Ni 0.4Zn 0.6Fe 2O 4 6mm
133 Ni 0.35Zn 0.65Fe 2O 4 7mm
135 Ni 0.50Zn 0.50Fe 2O 4 4mm
137 Ni 0.4Fe 2O 4 9mm
138 Ni 0.3Zn 0.7Fe 2O 4 10mm
139 Ni 0.25Zn 0.75Fe 2O 4 10mm
By result shown in Figure 6 as seen, solid solution (as the stacked patch block among Fig. 3) helps to design the patch block that can absorb in the frequency range that requires.Ni 0.4Zn 0.6Fe 2O 4, Ni 0.50Zn 0.50Fe 2O 4Solid solution forms 20dB or bigger reflection loss, Ni in whole television frequency scope 0.4Zn 0.6Fe 2O 4Be specially adapted to VHF, Ni 0.5Zn 0.5Fe 2O 4Be specially adapted to UHF.Ferrite is relevant with the permittivity and the magnetic permeability of the material that becomes with frequency as the ability of electromagnetic wave absorb.In this article, when using " permittivity ", its unit of being meant and dielectric constant relevant parameters.That is to say that the real part of " permittivity " equals dielectric constant.Fig. 7 and Fig. 8 represent ferrite solid solution Ni respectively 0.4Zn 0.6Fe 2O 4Electric permittivity epsilon and magnetic permeability μ.In Fig. 7, show the real part ε ' of permittivity and the imaginary part ε of permittivity " and be the relation of the frequency of unit with the gigahertz.In Fig. 8, shown the real part μ ' (dielectric constant) of magnetic permeability and the imaginary part μ of magnetic permeability " be the relation of the frequency of unit with the gigahertz.This curve is very enlightenment.In most of materials, the imaginary part ε of permittivity " and the imaginary part μ of magnetic permeability " much smaller than the real part of relevant parameter.But, in nickel-zinc ferrite, the imaginary part μ of magnetic permeability " and greater than the real part μ ' of magnetic permeability, the imaginary part μ of magnetic permeability in this ferrite " big especially.
" mixing " ferrite is to make multilayer ferrite absorber with the another kind of method of design absorber element 106.This multilayer ferrite absorber 106C is shown in Fig. 9.In this example of the present invention, absorber element 106C comprises two-layer or multilayer Ferrite Material 150 and 152, and layer 150 is different Ferrite Materials with layer 152.Equally, the width of absworption peak frequency and absorption curve is different and become with the thickness of each layer with ferritic kind in layer 150 and 152.In Figure 16, show for the multilayer absorber 106C that makes by Mn ferrite layer 150 and nickel-zinc ferrite solid solution layer 152 reflection loss (dB) of its five kinds of different-thickness combinations and the relation of frequency (GHz).The thickness of various Mn ferrite layers and the combination of nickel-zinc ferrite layer multi-layer is listed in table 3.
Table 3
The curve numbering MnFe 2O 4Thick (mm)/Ni 0.4Zn 0.6Fe 2O 4Thick (mm)
150 1/5
152 1.5/4.5
154 2/4
156 2.5/3.5
158 3/3
See that individually every kind of multilayer ferrite absorber forms the reflection loss greater than 20dB in the wide region that covers whole TV wave band 2/3 approximately.For example, MnFe that 1.5mm is thick 2O 4Layer and the thick Ni of 4.5mm 0.4Zn 0.6Fe 2O 4The curve 152 of the multilayer absorber that layer is combined shows that this absorber 106C can absorb the electromagnetic wave of whole VHF frequency zones efficiently.See on the whole, as seen from Figure 16, can the multilayer absorber 106C that be formed by the multilayer ferrite layer be designed, so that in the wide relatively frequency range of TV spectrum central authorities, crest frequency is migrated to any specific frequency place, and the absolute value of not obvious change reflection loss.
Figure 10 is another example 106D of absorber element 106 of the present invention.This example comprises high dielectric constant material 160, ferrite 162 and advanced low-k materials 164.Described high dielectric constant material 160 is ferroelectric ceramic material such as barium titanate (BaTiO preferably 3), although it also can be other high dielectric constant material such as BST or other ABO 3The superlattice material of type perovskite, other layering or video magnetic material such as BaTiO 3+ BaFeO 3Referring to the comprehensive description of the United States Patent (USP) 5,519,234 of the Araujo of on May 21st, 1996 bulletin for the superlattice material of layering.The video magnetic material comprises BaTiO 3+ BaFeO 3, BaTiO 3+ BiFeO 3And BaO3BaTiO 33Fe 2O 3Ferrite 162 is Ni preferably 0.4Zn 0.6Fe 2O 3Although it also can be above-mentioned other ferrite.Advanced low-k materials 164 better is a polymer, as Teflon TM, Merlon or polyethylene such as Butvar TM, but also can be the relative lighter dielectric materials of other plastics or other weight.
Figure 17 is the reflection loss (dB) of baffle 100 and the computer simulated plots of frequency (GHz) relation, and wherein the absorber element 106D of baffle 100 comprises the BaTiO of 1mm 50/50 3+ BaO6Fe 2O 3Solid solution, 5mm Ni 0.4Zn 0.6Fe 2O 3And 5mm Teflon TMThis baffle is about 30dB at the reflection loss in whole television frequency district, and this is the known so far best reflection loss of all baffles in this frequency range.It still is good airport absorber, because it can absorb electromagnetic wave well in the frequency range of the airport hierarchy of control (promptly about 0.1-0.4GHz).
Figure 11 shows another example 106E of absorber element 106, and wherein ferrite 166 and high dielectric constant material 170 are clipped in the middle polymer 168.The material preferably of this example is identical with the material of Figure 10 example, but ordering is different.Figure 18 is the reflection loss (dB) of baffle 100 and the computer simulated plots of frequency (GHz) relation, and wherein ferrite/the polymer of baffle 100/high dielectric constant material absorber element 106E comprises 5mm Ni 0.4Zn 0.6Fe 2O 3, 4mm Merlon and 1mm 70/30BST (be Ba 0.7Sr 0.3TiO 3).This example has the excellent absorption performance in the 800-900MHz frequency range, and therefore when the absorption in this scope be that crucial words (when being radio localized network (LAN) system as the electromagnetic wave of needs absorption) can form the excellent absorption plate.
Figure 12 shows another example 106F of electro-magnetic wave absorption body member 106.This example comprises polymer-ceramic composite bed 176, and the better polymerization thing is Merlon or polyethylene, although also can be Teflon TMOr any other polymer in light weight, that intensity is higher relatively.Can in polymer, mix any powdered ceramic material above-mentioned.Ceramic material is listed in table 4 preferably, has also listed real part of permittivity and imaginary part mean value ε ' and the ε of various materials at 100MHz-1GHz in this table ", and the average value mu of magnetic permeability real part and imaginary part ' and μ ".
Table 4
Material ε’ ε” μ’ μ”
20％BaTiO 3+80％BiFeO 3 40 1 1.0 0.1
40％BaTiO 3+60％BiFeO 3 90 8 1.1 0.1
50％BaTiO 3+50％BiFeO 3 100 10 1.2 0.1
60％BaTiO 3+40％BiFeO 3 200 32
80％BaTiO 3+20％BiFeO 3 300 30 1.2 0.1
60％BaTiO 3+40％BiFeO 3+1％Ni 48 4 1.3 0.1
60％BaTiO 3+40％BiFeO 3+4％Ni 53 5 1.3 0.1
4BaO·3TiO 2·3Fe 2O 3 3.6 Can ignore 1.0 0.1
BaTiO 3+BiFeO 3+Bi 4Ti 3O 12 180 10 1.0 0.1
Fe 3O 4 400 300 1.5 0.5
Barium ferrite (BaO6Fe 2O 3) 35 5 1.3 0.2
Barium ferrite+BaTiO 3 60 30 1.3 0.2
LSM 250 250
Strontium bismuth tantalate 65 0.6 1.0 0.1
The ferrosilicon oxysome 10 1 1 20
The experimental data of the composite material of carbonate polymer and some table 4 ceramic material and carbonate polymer is listed in table 5 preferably.Table 5 has also been listed real part and imaginary part mean value ε ' and the ε of various materials at the dielectric constant of 100MHz-1GHz ", the real part of magnetic permeability and imaginary part average value mu ' and μ ".
Table 5
Material Pottery weight % ε’ ε” μ’ μ”
Polymer 0 2.1 0.01 1.0 0.01
BaTiO 3·BiFeO 3 20 3.2 0.05 1.0 0.01
BaTiO 3·BiFeO 3 40 4.2 0.1 1.0 0.01
BaTiO 3·BiFeO 3 50 4.4 0.1 1.0 0.01
BaTiO 3·BiFeO 3 75 6.5 0.3 1.0 0.01
4BaO·3TiO 2·3Fe 2O 3 40 4.0 0.08 1.0 0.01
Fe 2O 3 40 6.0 0.8 1.0 0.01
Barium ferrite 40 4.0 0.2 1.0 0.01
BST(Ba xSr (1-x)TiO 3) 40 7.0 0.05 1.0 0.01
Figure 19 is the reflection loss (dB) of baffle 100 and the computer simulated plots of frequency (GHz) relation, and wherein the polymer-ceramic composites absorber element 106F of baffle 100 comprises 13mm 50% Merlon and 50% (0.25BaTiO 3+ 0.75BiFeO 3).It shows good absorbability in high frequency radio wave spectrum district.
Figure 13 shows an example 106G of absorber 106 of the present invention, and it comprises ferrite 108 and material 182.This example is identical with Fig. 3 example, but out of position with respect to electromagnetic radiation incident wave 110 ferrites 180 and material 182.Ferrite 180 can be table 1 any ferrite listed or that mention when describing Fig. 3.For TV applications, better be nickel-zinc ferrite, especially Ni 0.4Zn 0.6Fe 2O 4Material 182 can be table 1 any material listed or that mention when describing Fig. 3.Equally, dielectric material is preferably, although the result who provides at some other material (as LSM) of some frequency range is better than the result that dielectric material provides.In this example, according to ferritic difference, find that low or high dielectric constant materials all can provide good result.Should note under the situation of the more close incident electromagnetic wave 110 of dielectric material (being Fig. 3 example), high dielectric constant materials preferably, and be placed under the situation between ferrite and the metal 104 (as Figure 13) at dielectric material, advanced low-k materials (being that dielectric constant is up to 10 material) also can provide good result.Although this is not good absorber in the MHz frequency range for advanced low-k materials, be placed between ferrite and the metal after, they are the overall absorption performance of improved system 100 significantly.
Figure 20 is the computer simulated plots of reflection loss (dB) and frequency (GHz) relation of the ferrite/high dielectric constant material electromagnetic wave absorb 106G of five kinds of different-thickness, and wherein absorber element 106G comprises Ni 0.4Zn 0.6Fe 2O 4As ferrite, BST is as dielectric material 182.In this instantiation, do not use reflector 104.The thickness of the ferrite layer 180 of each curve is listed in table 6.The thickness of dielectric material 182 is enough to make electromagnetic wave can not penetrate sample, and perhaps for the needs of computer simulation, its thickness is infinitely great.In fact, for many materials, several inches or one foot thick material thickness can prevent that electromagnetic radiation from penetrating sample.Because electromagnetic radiation do not penetrate sample, it is not that to be absorbed be exactly to be reflected, and therefore reflection loss becomes suitable the measuring of absorbent properties once more as before.
Table 6
The curve numbering Thickness (mm)
200 3
201 4
202 5
203 6
204 7
As seen from the figure, be high for a kind of its absorbability of dielectric material thickness, other is then relatively low.Therefore, the thickness of electro-magnetic wave absorption body member 106G seems even more important when areflexia element 104.Another computer simulated plots of electromagnetic wave absorb 106G example is that ferrite 180 is Ni in the sample 0.4Zn 0.6Fe 2O 4, material 182 is for LSM and comprise the curve of metal backing liner plate 104.The result is similar to the curve of Figure 20, is about 32dB but absorb, and absorbs and do not resemble the strong thickness that depends on Figure 20.It is thick for 5mm that maximum absorption occurs in ferrite 180, and LSM is that 5mm is thick.Another computer simulated plots of electromagnetic wave absorb 106G example is that ferrite 180 is Ni in the sample 0.4Zn 0.6Fe 2O 4, material 182 is magneto-plumbite type Ba 4Ti 3Fe 6O 19And comprise the curve of metal backing liner plate 104.The result is similar to the curve of Figure 20, but minimal absorption is about-29dB, and absorbs and not resemble the strong thickness that depends on Figure 20.It is thick for 5mm that maximum absorption occurs in ferrite 180, and magneto-plumbite type is that 5mm is thick.The 4th computer simulated plots of electromagnetic wave absorb 106G example is that ferrite 180 is Ni in the sample 0.4Zn 0.6Fe 2O 4, material 182 is aluminium oxide Al 2O 3And comprise the curve of metal backing liner plate 104.The dielectric constant of aluminium oxide is about 9.The result is similar to the curve of Figure 20, but minimal absorption is about-39dB, that is to say to absorb the absorption be a bit larger tham among Figure 20, and absorbs and do not resemble the strong thickness that depends on Figure 20.It is thick for 5mm that maximum absorption occurs in ferrite 180, and aluminium oxide is that 1mm is thick.Aluminium oxide can be made by liquid deposition methods, and it is used for other dielectric material and ferritic process for preparing ceramic is simpler than as herein described in some aspects, therefore uses this example of aluminium oxide to be better than other example to a certain extent.
Figure 14 and Figure 15 are two examples in addition of the absorber system that is easy to regulate.In Figure 14, absorber 106H comprises polymeric layer 186 and another dielectric materials layer 188.In Figure 15, absorber 106I comprises dielectric materials layer 190 and polymeric layer 192.Be preferably, dielectric material 188 and 190 dielectric constant are higher than the dielectric constant of polymer 186 and 192 respectively in each example.Significantly surpass 20dB although reveal good controllability and reflection loss, do not have a kind of Fig. 3 of having, 10 and 11 examples good absorption characteristic like that in the combination of materials that actual tests is crossed at these example tables of some frequency range.In these two kinds of examples, the better polymerization thing is Merlon or polyethylene, and dielectric material is BST preferably, although also can use other polymer and dielectric material.Because absorber 106H makes easily with 106I and weight is relative lighter, so their particular importances.
Figure 21 is another example 106J that can provide the absorber 106 of good result.Absorber element 106J comprises ferrite layer 194, low dielectric constant material layer 196 and high dielectric constant material layer 198.This 106J example is identical with Figure 11 example, but it is extended to and comprises any advanced low-k materials 196, and is not only polymer.Silex glass is suitable advanced low-k materials, and ferrite 194 and high dielectric constant material 198 can be referring to the descriptions of Figure 11 preferably.This example of scalable 106J is to provide the performance roughly similar to the example 106E of Figure 11.To ferrite 194 is Ni 0.4Zn 0.6Fe 2O 4, dielectric material 196 obtains the reflection loss curve for silex glass and dielectric material 198 for the absorber 106J of BST carries out computer simulation.The best absorber 106J middle level 194 that is absorbed as is that 5mm is thick, and layer 196 is that 4mm is thick and layer 198 is thick for 1mm.This absorber is higher than 20dB at the reflection loss of whole TV spectral regions, and peak absorbance is near 35dB.
Figure 22,23 and 24 is several examples, and how expression is applied to above-mentioned stacked principle in the multilayer absorber 106.In the 106K of Figure 22 example, have one deck ferrite layer 210 and three layers of dielectric materials layer 212,214 and 216.Above-mentioned any ferrite all can be used as ferrite 210, and above-mentioned any dielectric material all can be used as the dielectric material of these examples, it should be noted that dielectric material 214 is different from dielectric material 212 and 216.An example of this example is that ferrite 210 is Ni among the absorber 106K 0.4Zn 0.6Fe 2O 4, dielectric material 212 is that polymer, dielectric material 214 are that LSM, dielectric material 216 are BST.Reflection loss (dB)-frequency (GHz) curve that obtains with computer simulation for different material thicknesses is shown in Figure 25.The thickness of material is listed in table 7.
Table 7
The curve numbering Ferrite thickness (mm) Polymer thickness (mm) LSM thickness (mm) BST thickness (mm)
250 5 2 2 1
252 4 2 2 2
254 5 3 3 1
256 5 2 2 1
258 4 2 2 2
The present invention's imagination can be used more multi-layered dielectric material.Because dielectric materials layer is thinner relatively, therefore be easier to form this multi-layer sheet relatively.
The absorber 106 of the 106L example of Figure 22 comprises ferrite layer 220, polymeric layer 222, second ferrite layer 224, the second polymer layer 226 and the 3rd ferrite layer 228.Equally, can use any above-mentioned ferrite and polymer.Figure 26 is the computer mould graphoid of reflection loss (dB)-frequency relation of absorber 106L, and ferrite 220,224 and 228 is Ni in this 106L 0.4Zn 0.6Fe 2O 4, polymer 222 and 226 is a Merlon, its performance is listed in table 5.Each layer thickness of each curve is listed in table 8.
Table 8
The curve numbering Ground floor ferrite thickness The ground floor polymer thickness Second layer ferrite thickness Second layer polymer thickness The 3rd layer of ferrite thickness
260 2 2 2 2 2
262 2 2 1 3 2
264 2 3 1 3 1
266 1 3 2 3 1
268 2 3 1 2 2
Absorber 106 shown in the example 106M of Figure 24 comprises n group ferrite/polymeric layer, and wherein n is greater than 1 and be preferably 100 or less than 100.That is to say that the basic absorption body member of example 106M is one deck ferrite layer 230 and one layer of polymeric layer 231.Be repeated n time with the numeral 1 basic absorption body member of representing as shown in the figure.Ferrite can be above-mentioned any ferrite, and polymer can be above-mentioned any polymer.Be preferably, ferrite is identical respectively with polymer in each absorber element, although the present invention's imagination can use the material different with other element to make a kind of or all 1-n absorber elements.Figure 27 is the computer simulated plots of absorber 106M reflection loss (dB)-frequency relation, and ferrite 230 is Ni in absorber 106M 0.4Zn 0.6Fe 2O 4, polymer 231 is a Merlon, its performance is listed in table 5, n=50.The thickness of the thickness of ferrite 230 and polymer 231 is listed in table 9 in the basic absorption body member of each curve.
Table 9
The curve numbering Ferrite thickness (μ m) Polymer thickness (μ m)
270 100 100
272 200 200
274 100 50
276 95 100
278 105 100
To the analysis showed that of above-mentioned all results, best absorber 106 may be a 106N example shown in Figure 30.This absorber 106N comprises the high μ that is clipped in high dielectric constant material 300 and advanced low-k materials 304 centres " material 302.Be preferably, high dielectric constant material is the light incident side 110 of close electromagnetic radiation, the most close supporting structure 100 of advanced low-k materials and metallic reflective material 104.Be preferably the imaginary part μ of the magnetic permeability in intermediate layer 302 " not only bigger, but also greater than the real part μ ' of magnetic permeability.Be preferably, the dielectric constant of high dielectric constant material is 100 or bigger, and advanced low-k materials is 5 or littler.
Above-mentioned in the art progress is experiential result.In general, the inventor thinks that for some material (as ferrite), good result is owing to the high μ of these materials ".But, be difficult to explain the many good result that obtained, especially because employed many materials do not have the performance of determining easily of energy explanation results.The above results is anatomized, think that at present some good absorbent properties is relevant with the principle of quarter wave plate.In the quarter wave plate absorber, be the front that the material of wavelength 1/4 places 100% reflecting material (as metal level) with thickness.That is to say that this principle of absorption is only effective at following thickness:
(1)t＝λ eff/4
Wherein, λ Eff=λ/(ε ' μ ') 1/2, λ is the wavelength of incident wave.See roughly as if because the thickness of material therefor far is thinner than 1/4 of typical TV wavelength, and equation (1) only could set up, so it can not provide aforesaid wide relatively absorption in very narrow wave-length coverage.But in high dielectric constant material, the electromagnetic wavelength of given frequency is short more than its aerial wavelength.In addition, if for the structure of some absorber 106, ε ' μ ' is relevant with frequency, makes:
(2)f＝1/(ε’μ’) 1/2
Wherein f is that wavelength is the electromagnetic frequency of λ, and then this structure all is good absorber in the whole frequency range that equation (2) is set up.If a kind of effective ε ' μ ' of absorbent structure obeys equation (2) in a wide relatively frequency range, that is to say, if in wide frequency range
(3) (ε ' Effμ ' Eff) 1/2～1/f or
(4)n eff～1/f
Wherein, n EffBe effective refractive index, this structure will be good absorber so.Can find for many materials of the present invention, μ ' referring to top table 4 and table 5 Eff=1 or very near 1.With the structure that several these materials make, its μ ' EffAlso can equal 1 or very near 1.That make with these materials and in specific frequency range
(5)(ε’ eff) 1/2～1/f
Structure will be good absorber in this frequency range.
By top description as seen, any material or structure that effective over a range of frequencies ε ' μ ' descends with frequency, perhaps over a range of frequencies effective dielectric constant descend with frequency and in this frequency range μ ' be 1 or near 1 any material or structure, as long as the thickness that its thickness provides near equation (1), it generally is good absorber in this frequency range of part so at least.That is to say that ε ' has increased the scope that quarter-wave relational expression (1) is roughly set up with frequency this fact that descends, thereby increased the scope that material or structure become effective quarter wave plate.It is wide more that the reducing more near equation (5) of effective dielectric constant in this scope, structure become the frequency range of good absorber.Remembeing this point, just can be regarded as what nickel-zinc ferrite from Fig. 7 and 8, when itself and high dielectric constant material are combined, is good absorber in wide frequency range especially.
Another key factor that forms good absorption is the impedance matching of adjacent layer.That is to say that the impedance of adjacent layer should be equal substantially.Near the layer of reflecting plate 100 outer surfaces, this means that impedance should be 1 or near 1, because the impedance of air is 1 for.If the impedance of adjacent layer differs greatly, electromagnetic wave can reflect at the interface of two interlayers, and internal layer will can not participate in absorbing significantly.Impedance is defined as z=([μ ' i μ "]/[ε '-i ε "]) 1/2Although this is the expression formula of a complexity, its performance is difficult to understand intuitively, can recognize ε " and μ " be basically on the basis of loss with its simplification, therefore (μ '/ε ') 1/2It is the major parameter that needs coupling.The impedance of air is 1.Fig. 7 and Fig. 8 are presented in the very wide frequency range near 200MHz, for Ni 0.4Zn 0.6Fe 2O 4, μ ' ≈ ε ', therefore (μ '/ε ') 1/2Near 1.When this ferrite also being satisfied this synthesis in fact of the described condition of leading portion and consider together, this is true just to illustrate that this material is the reason of good absorber.
Can clean out the method preferably of design absorption of electromagnetic radiation plate by top description.At first, seek refractive index with the combination of materials that has good absorption in frequency decline and near the frequency range the frequency range that will absorb.Subsequently, regulate this combination, make the more approaching desirable equation of its refractive index (4), thereby enlarge the scope that absorbs.If necessary, go back the relative thickness of adjustable material and material so that move the peak absorbance frequency, and make the impedance matching of adjacent layer as far as possible, in an iterative process, again the combination of materials that forms is adjusted to more near equation (4) subsequently.
Have found that the material with the effective dielectric constant that reduces with frequency is well suited for as the top layer, i.e. the layer of the electromagnetic radiation 110 of close incident is to improve the electromaganic wave absorbing property of multilayer absorber system.
In the above description, many examples contain the polymer-ceramic composition.The manufacturing flow chart of this composition is listed in Figure 28.In step 284, the solvent 282 of the ceramic powder 280, polymer powder 281 and the soluble polymeric thing that require is mixed earlier.For example, if polymer is Butvat TM, then suitable solvent is oxolane (THF).Ceramic powder suspension is in solution.It is even until it to mix the solution that obtains, and is poured in the mould in step 286 subsequently.Follow the time under suitable temperature that this composite material solidification is suitable.For example, for Butvar TM, suitable temperature is a room temperature, the suitable time is 12 hours.
As seen by above-mentioned, polymer-ceramic composites has several advantages than conventional absorber.They are not only in light weight, and at room temperature make easily.They can easily mix the material of several different performances (as ferroelectric and ferrite, perhaps high dielectric constant material and ferrite), solve special reflectivity problem to regulate material.In addition, the absorber 106 of formation is soft relatively, easier operation and carry out routine building.
Many dielectric materials, ferroelectric, ferrite that are used for absorber 106 of the present invention etc. all are ceramic materials.All these ceramic materials make by the described method of Figure 29.In step 291, the ceramic powder that requires is placed mould.This mould is preferably made by stainless steel.In step 292, with powder hydrostatic pressing in mould, pressure is preferably 50,000 pounds/square inch (PSI).In step 6, take out pottery and sintering from mould subsequently, sintering temperature is preferably 900-1100 ℃.Further sample is shaped if necessary and test subsequently.If this test is the dielectric test, the disc sample that then takes out from mould itself is suitable.For the magnetic sample, before test, on sample, hole and make it to form the shape of ring.
One of the present invention is characterised in that, compare the stacked absorber volume of the present invention with existing absorber littler and lighter.For example, the thickness preferably of the invention described above high dielectric constant material than existing ferritic better thin thickness 2-10 doubly.In addition, many high dielectric constant materials (as BST) are the hardened ceramic of anti-Weather.Therefore, can save outer protection patch block 109 or make it thinner.
Another is characterised in that the present invention, finds that the dielectric constant of material is high more, and material just can be thin more, and still can provide good absorbability with other combination of materials together.
Another is characterised in that the present invention, and the critical thickness t of a corresponding optimal absorption performance is arranged for material of the present invention or works c, have good absorbent properties near the thickness range this critical thickness.
Of the present invention another is characterised in that, its DIELECTRIC CONSTANT ' material that becomes with frequency can form good absorber, in the time of especially can in wide frequency range, making combination of materials that effective dielectric constant satisfies formula (3) together with itself and other.
Of the present invention another is characterised in that, in fact can relatively easily all examples of the present invention be adjusted to the characteristic frequency in TV and the high frequency radio wavelength scope.This can be by changing each example composition, change the thickness of each composition, maybe when relating to composite material or solid solution, change the amount of each component or be used in combination said method and implement.Therefore, baffle of the present invention itself can solve the specific electromagnetic wave environmental problem in special building place.
Of the present invention another is characterised in that nickel-zinc ferrite is the best ferrite that is used to absorb, and the Ni of this material 0.4Zn 0.6Fe 2O 4Stoichiometry is best.Several different stoichiometry preparations have been discussed above.Nickel-zinc ferrite can also mix (as with magnesium or other metal), but finds that unadulterated ferrite is best in the television frequency scope.
Of the present invention another is characterised in that, although advanced low-k materials is not good absorber in the MHz frequency range, when it being clipped between ferrite and the metal, they can improve the overall absorption performance of electro-magnetic wave absorption plate body system.
Think the present invention's example preferably at present although described, it should be understood that and under the situation that does not depart from the present invention's spirit and essential characteristic, to use other special form to implement the present invention.Now described and used the advantage of multilayer absorber of the present invention, but also can propose the many improvement and the variation of these absorbers.Therefore, example of the present invention is an illustrative and nonrestrictive.Scope of the present invention is stated clearly by appending claims.

Claims (12)

1. electro-magnetic wave absorption plate (100) that is used for construction of buildings, this baffle comprises: building supporting member (102) and the absorber element (106) that is supported by this supporting member, compare with described supporting member, the incidence point of the more close described electromagnetic wave of described absorber element on described baffle is characterized in that:
Described absorber element (106) has the layer structure that comprises the ground floor and the second layer,
It is 20 or higher high dielectric constant material that described ground floor comprises dielectric constant, and this material comprises the component that is selected from following material:
La xSr (1-x)MnO 30＜x in the formula＜1 (LSM);
Ba xSr (1-x)TiO 30＜x in the formula＜1 (BST);
La xCa (1-x)MnO 3, 0＜x in the formula＜1;
La xPb (1-x)MnO 3, 0＜x in the formula＜1;
The superlattice material of layering;
ABO 3The type perovskite; With
The video magnetic material; With
It is 10 or lower advanced low-k materials that the described second layer comprises dielectric constant.
2. electro-magnetic wave absorption plate as claimed in claim 1 is characterized in that described high dielectric constant material comprises the homogeneous mixture of at least two kinds of different materials.
3. electro-magnetic wave absorption plate as claimed in claim 1 or 2 is characterized in that described advanced low-k materials comprises the component that is selected from aluminium oxide, silex glass, ferrite and polymer.
4. electro-magnetic wave absorption plate as claimed in claim 3 is characterized in that described advanced low-k materials comprises the homogeneous mixture of at least two kinds of different materials.
5. as claim 3 or 4 described electro-magnetic wave absorption plates, it is characterized in that described advanced low-k materials comprises the ferrite that is selected from nickel-Zn ferrite, copper-Zn ferrite, cobalt-Zn ferrite and Mn ferrite.
6. electro-magnetic wave absorption plate as claimed in claim 1 is characterized in that comparing with the described second layer, the incidence point of the more close described electromagnetic wave of described ground floor on described baffle.
7. electro-magnetic wave absorption plate as claimed in claim 1 is characterized in that comparing with described ground floor, the incidence point of the more close described electromagnetic wave of the described second layer on described baffle.
8. electro-magnetic wave absorption plate as claimed in claim 1 is characterized in that described absorber element (106) also comprises the 3rd layer of contain ferrite,
Compare with described the 3rd layer, the incidence point of the more close described electromagnetic wave of described ground floor on described baffle,
Compare the incidence point of described the 3rd layer of more close described electromagnetic wave on described baffle with the described second layer.
9. electro-magnetic wave absorption plate as claimed in claim 1 is characterized in that described absorber element (106) also comprises the 3rd layer of contain ferrite,
Compare with the described second layer, the incidence point of described the 3rd layer of more close described electromagnetic wave on described baffle,
Compare the incidence point of the more close described electromagnetic wave of the described second layer on described baffle with described ground floor.
10. as each described electro-magnetic wave absorption plate among the claim 1-9, it is characterized in that described baffle also comprises the reflecting element (104) by described supporting member (102) supporting,
Compare the incidence point of the more close electromagnetic wave of described absorber element (106) on described baffle with described reflecting element (104).
11. electro-magnetic wave absorption plate as claimed in claim 10 is characterized in that this baffle can absorb electromagnetic wave over a range of frequencies effectively,
Described absorber element (106) has the effective real part ε ' of permittivity EffWith the effective real part μ ' of magnetic permeability EffMake in described frequency range (ε ' Effμ ' Eff) 1/2～1/f, wherein f is the frequency of incident electromagnetic wave.
12. electro-magnetic wave absorption plate as claimed in claim 10 is characterized in that this baffle can absorb electromagnetic wave over a range of frequencies effectively,
Described absorber element (106) has the effective real part ε ' of permittivity that descends with frequency Eff
CN98800025A 1997-01-13 1998-01-12 Electromagnetic wave absorption panels and materials for same Expired - Fee Related CN1128485C (en)

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US08/782,934 1997-01-13
US08/782,938 US5853889A (en) 1997-01-13 1997-01-13 Materials for electromagnetic wave absorption panels
US08/782,934 US6037046A (en) 1997-01-13 1997-01-13 Multi-component electromagnetic wave absorption panels
US08/782,938 1997-01-13

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CN1128485C true CN1128485C (en) 2003-11-19

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CN103452200A (en) * 2012-05-30 2013-12-18 深圳市栢富电子有限公司 Wave absorbing assembly and manufacturing method and microwave unreflected chamber and construction method
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WO1998031072A1 (en) 1998-07-16
EP0900458A1 (en) 1999-03-10
JP2000507400A (en) 2000-06-13
CN1216166A (en) 1999-05-05
EP0900458B1 (en) 2006-11-22
DE69836457D1 (en) 2007-01-04
DE69836457T2 (en) 2007-09-13
KR20000064579A (en) 2000-11-06

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