CN1362006A - A method for attenuating electromagnetic interference, an electromagnetic interference attenuation device - Google Patents
A method for attenuating electromagnetic interference, an electromagnetic interference attenuation device Download PDFInfo
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- CN1362006A CN1362006A CN99816809.2A CN99816809A CN1362006A CN 1362006 A CN1362006 A CN 1362006A CN 99816809 A CN99816809 A CN 99816809A CN 1362006 A CN1362006 A CN 1362006A
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- H—ELECTRICITY
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Abstract
An EMI attenuation device including at least two substrates such that the spacing between these substrates is selected to maximize shielding performance at a particular frequency. The device further includes an additional substrate arranged at predetermined distances from the first two substrates to optimize shielding performance.
Description
Invention field
The present invention relates to the electromagnetic interference (EMI) shielding, more specifically, use multilayer screen substrate to optimize and be higher than under the frequency of 100MHz, the particularly decay of the electromagnetic interference (EMI) under the higher frequency with transparent structure.
Background technology
Has continuous electromagnetic radiation in the air of industrialization society.This class electromagnetic radiation is present in the very big frequency range, is typically the radio wave that electric device sends.Although think that now the electromagnetic radiation of medium level is harmless relatively to vital tissues, can damage electronic instrument and equipment in some work.
In some cases, need radome to isolate sensitive device and be not subjected to effect of electromagnetic radiation, these devices comprise the Electronic Testing and the enciphered data communication of nulcear magnetic resonance (NMR) (NMR) imaging, communication device.Usually, the emission of electronic equipment also needs to be included.The EMI shielding often is continuous coated realization the by one or more layers metallic conduction material of coating (for example, copper, aluminium, bronze or steel) on the radome wall.Screen is usually in single-point grounding, and the electromagnetic energy that radome is absorbed imports in the earth.Very close to each other in this conductive shield is vital, even also be like this there being the position such as holes such as door or windows.
Usually on various radomes, need window, so that observer, custodian and operating technology person can monitor situation about taking place in the radome outside in radome.In the NMR imaging, be also referred to as magnetic resonance imaging (MRI), patient and very responsive MRI equipment all are in the EMI radome.Create noiseless environment like this, avoided in final image, occurring artificial image or image deflects.The shield grid that designs in the EMI attenuating device and the exemplary of window are disclosed in U.S. Patent number 4701801,5012041,5017419,5239125 and 5295046.
The window of EMI/RFI radome must shield, and exists continuous electric to contact with the radome wall.And the window substrate must have enough " transparency " and " saturating sound " arranged in some cases, allows the control personnel to monitor outside.Therefore, need make the window substrate cause optical skew to minimize.
The window that comprises the glass of individual layer or double layer screen grid, optically transparent plating or the combination of transparent plastic or other electric conducting material or above-mentioned substance etc. is at the optically transparent decay EMI that is applied to simultaneously.Shield effectiveness depends on each parameter, and these parameters comprise the thickness and the kind of shield grid mesh pattern, line footpath, grid number and electric conducting material.
When using shield grid, a shield effectiveness factor (S
E) be between the gridline of each individually shielded grid the function of distance (g).Can be expressed as following equation:
S
E＝f(g)
When g=0, the electric field decay increases under high frequency., this also causes the reduction of final substrate " transparency " and " saturating sound ".
The window that is made of one deck shield grid has certain EMI damping capacity, but is being higher than under the frequency of 1MHz, the power power of the every increase 10 of frequency, and this EMI fade performance reduces about 20dB.This be illustrated in White Donald R.J's " electromagnetic shielding material and performance thereof ", second edition in 1980 (Don White consultants, Inc., Gainesville, Virginia).As a result, along with frequency obviously increases, see through the electromagnetic radiation of significant amounts from single shielded gate structures.
The window of being made up of two-layer parallel shield grid has improved decay, and the double shield grid EMI window of this example shown in being disclosed in United States Patent (USP) 5012041 is referred to here as a reference.United States Patent (USP) 5012041 points out, uses to comprise each other different and the decay EMI and reduce moire pattern of two different parallel shield grids of distance to each other of wire size.
, the present inventor finds be higher than 100MHz, and particularly in the frequency range of 1GHz to 10GHz, the fade performance that two parallel shielded gate structures produce takes place unusual.This unusual be the function of shield grid separation distance, when the distance of separating two plane shield grids equals half the integral multiple of wavelength (λ) of incident electromagnetic wave, this unusually especially serious.Here wavelength is by equation c=f lambda definition, and c is the light velocity, and f is a wave frequency.In these cases, each respective frequencies and and integral multiple, space between shield grid constitutes a resonant cavity.This cause resonance frequency and harmonic wave position thereof or near, the EMI fade performance significantly reduces.The existence that this resonance is propagated causes the problem of imager, and for example, for the signal that goal in research is sent, consequent transmission ray may be wrong.And the present inventor finds that also can resonance take place in any frequency propagates.As the result of this resonance generation phenomenon, under certain frequency, to compare with single shield grid system, the double shield grating system has worse attenuation characteristic.
Do not consider the relative separation distance between shield grid, can produce adverse effect at the textural simple interpolation additional mask grid of double shield grid.This is that it is the function of distance between the shield grid because the additional mask grid can be introduced additional resonance frequency.
There are such needs technically, promptly are provided under the frequency that is higher than 100MHz,, improve the method and apparatus of EMI fade performance, have enough " transparency " and " saturating sound " characteristic simultaneously particularly in the frequency range of 1GHz to 10GHz.These method and apparatus should use business-like material, also should keep in repair easily and replace simultaneously.
Summary of the invention
An object of the present invention is to provide a kind of EMI screen method and device, can overcome many shortcomings of the prior art with optimized attenuation performance.
Another object of the present invention provides the method for a kind of EMI that decays under various frequencies.A feature of the present invention is arranged in juxtaposition the surface that is made of light weight, electric conducting material transparent and saturating sound toward each other with pre-determined configurations, so that the EMI of first series material decay input, and the EMI that second series is further decayed and was attenuated.An advantage of the invention is and reduced of the propagation of resonant electromagnetic wave ray, thereby optimize in the performance that is higher than under the specific frequency of electromagnetic radiation of 10MHz by multilayer material.
Another purpose of the present invention provides a kind of device, and it has the EMI shielding properties of the Reduction Level that meets or exceeds 100 decibels (dB) under the 10GHz at frequency 100MHz.A feature of the present invention is to combine a plurality of shield grids that are made of electric conducting material.An advantage of the invention is that under transparent and/or saturating sound environment accumulative total obtains high-caliber EMI/RFI shielding properties.
A further object of the invention provides a kind of EMI attenuating device that comprises light weight shield grid or other conduction and optically transparent material.A feature of the present invention is to be arranged in juxtaposition the shield grid surface toward each other.An advantage of the invention is and made up cavity that these cavitys have hindered radiated electromagnetic wave resonance and the harmonic wave under interested EMI frequency, thereby reduce the propagation of EMI in substrate.
In brief, the invention provides the device of a kind of EMI of decay, comprise first electric-conductor of arranging at spatial neighbor second electric-conductor; The 3rd electric-conductor of arranging at described second electric-conductor of spatial neighbor, wherein said first electric-conductor is different from described second electric-conductor in space and the 3rd electric-conductor spaced apart distance in the space and the second electric-conductor spaced apart distance.
The present invention also provides a kind of method that electromagnetic radiation is propagated that reduces, and comprising: make electromagnetic radiation enter the zone that stops the electromagnetic radiation propagation ducts, and the generation and the propagation ducts that stop electromagnetic radiation resonance.
The present invention also provides a kind of method of the electromagnetic radiation that decays, and comprising: make electromagnetic radiation enter to have a plurality of resonant cavities of different size and resonance frequency, so that radiation resonance is stoped by described other resonant cavity in particular cavity.
A kind of window that uses with the EMI radome is provided, and this window comprises at least two conductive surfaces, and two neighbouring surfaces are not parallel.
The present invention provides a kind of method of the electromagnetic radiation that decays again, comprising: make electromagnetic radiation impact first conductive substrate, first's electromagnetic radiation does not as a result see through or passes first substrate and the second portion electromagnetic radiation sees through first substrate; And make that seeing through next electromagnetic radiation now enters in the part that stops the electromagnetic radiation generation resonance frequency that sees through now.
In another embodiment, the invention provides a kind of device of the electromagnetic interference that decays, comprise one first restriceted envelope, have a plurality of walls that utilize first and second conductive shielding parts to constitute; One second restriceted envelope has a plurality of walls that utilize described second conductive shielding part and the 3rd conductive shielding part to constitute; And the part of locating first, second and the 3rd shielding part, wherein be different from the corresponding conllinear distance between the described second and the 3rd conductive shielding part adjacent wall in the distance between the described first and second conductive shielding part adjacent wall.
Also have, another embodiment of the invention is a kind of EMI attenuating device, comprises two conductive surfaces, wherein utilizes an average distance to separate described surface, and wherein said average distance is chosen as and obtains the maximum attenuation effect under preset frequency.
The simple declaration of accompanying drawing
The present invention with above-mentioned and other purpose and advantage from the detailed description of the embodiment of the present invention that is shown in accompanying drawing, can be understood best.
Fig. 1 is a partial elevation view according to electromagnetic wave attenuation device of the present invention;
Fig. 2 A is the sectional view along Fig. 1 cathetus 2-2, expression according to feature of the present invention, be used to install the exemplary means of conductive substrate to the support;
Fig. 2 B is a sectional view, and expression is according to another exemplary means of feature of the present invention, installation conductive substrate;
Fig. 2 C is a sectional view, and expression is according to another exemplary means of feature of the present invention, installation conductive substrate;
Fig. 2 D is a sectional view, and expression is according to another exemplary means of feature of the present invention, three conductive substrates of installation;
Fig. 3 is a curve chart, when expression is used one, two, three layer of conductive substrate according to the present invention, shields to the EMI in the 5GHz frequency range at 1.5GHz;
Fig. 4 is a curve chart, when expression is used one, two, three layer of conductive substrate according to the present invention, shields to the EMI in the 11GHz frequency range at 6GHz;
Fig. 5 A is an end view, and expression is according to window feature of the present invention, that comprise non-parallel conductive surface;
Fig. 5 B is an end view, and expression is according to a modification structures of window feature of the present invention, that comprise non-parallel conductive surface;
Fig. 5 C is an end view, and expression is according to another modification structures of window feature of the present invention, that comprise non-parallel shield grid;
Fig. 6 is a curve chart, and expression is used parallel according to the present invention and during non-parallel conductive surface, shielded to the EMI in the 5.1GHz frequency range at 1.5GHz;
Fig. 7 is a curve chart, and expression is used parallel according to the present invention and during non-parallel conductive surface, shielded to the EMI in the 11GHz frequency range at 7GHz.
The specific embodiment
Proposed to utilize the method and apparatus of lightweight materials decay EMI. Uniqueness of the present invention Part is, acceptable " transparent " and/or " thoroughly sound " performance is provided in the light weight structure, Be higher than the fade performance that also provides excellent more than the frequency of 100MHz simultaneously. The present invention can Be applied in shielding protection is provided on the high surface area. The present invention also can be applied on the radome and provide Window does not but have the barrier integrity of negative effect radome to tying with typical two-layer shield grid The same degree that structure is seen.
Usually, method and apparatus of the present invention combines such part, and they are decay input and/or output EMI significantly, and the vibration of the residue of damping subsequently EMI is with the remaining resonance electromagnetic radiation that decays.Under EMI frequency, can realize that decay is approaching or surpass 100dB up to 10GHz.The present invention is specially adapted at frequency 1GHz to these higher Reduction Levels are provided between the 4GHz.
The present invention is particularly useful on the shield effectiveness of optimizing specific wavelength.This " optimization " is by change surrounding the contiguous shielded surfaces relative shape and/or the distance of this device, thereby to the tuning and realization of this device.
Attenuating device generally includes a plurality of surfaces, and with the conductive shield grid of preset distance, parallel or non-parallel layout, it strengthens fade performance by a plurality of chambers or chamber such as each other.The EMI that injects except initial decay does not have any remaining EMI of conductively-closed grid initial decay by non-complete propagation (promptly propagate, reflection or out-phase reflect again), and the shield grid of Bu Zhiing also makes any sympathetic response of the EMI of input produce or resonance minimizes in advance.This propagation occurs in the cavity that is formed by a plurality of conductive substrates of arranging.The shield grid of arranging with definite shape has begun to stop effectively a part of EMI that injects, and has prevented the coherent superposition of residue EMI.
For example, in comprising the structure of three or more conductive substrates, first and second substrates in the most close EMI source EMI that is used to decay, and other substrate or the base wafer assembly residue EMI that further decays.This layout optimization the performance of the present invention under characteristic frequency.Depend on target frequency, each other distance of substrate, the shape/profile that each is surperficial are tested derivation, guarantee best fade performance.
An exemplary EMI attenuating device with feature of the present invention is illustrated among Fig. 1, and it is enclosed in the wall 14 such as the radome 16 of a chamber.Be installed on the wall 14 is that an overall labeling is 18 and according to the attenuating device of the present invention of principle of the invention structure.In order to obtain high EMI shielding at frequency 1GHz in the 10GHz scope, attenuating device 18 has improved a plurality of substrate configuration 19.
Comprise that the radome 16 of wall can have the structure of any preferred type.Above-mentioned wall comprises an opening 20, holds the window with the many substrate configuration of the present invention or has the template of the many substrate configuration of the present invention.Fig. 2 A is the vertical cross-section diagram along Fig. 1 cathetus 2-2, as Fig. 2 A institute more clearly as described in, the screen 17 of metal is continuously around whole chamber on wall 14 outer surfaces, its edge extends to opening 20, has continuous electrically contacting thereby give being arranged between opening inner shield module 18 and the screen 17.Module 18 utilizes fixture 21 to be fixed on the window.
Can be applied on the big sheet material although multi-screen of the present invention covers the grid base sheet, the EMI fade performance is given big radome surface, less module substrate also can have identical shield grid spare location.The details of three substrate modular structures
Shielding harness of the present invention comprises a plurality of shielding substrates.Although the common smooth surface of these substrates is needn't be smooth or be the plane.And the relative conllinear of these substrates arranges that such substrate is a benchmark, other substrate near or away from layout.
Illustrate to describe as Fig. 2 A, 2B, 2C and 2D, an exemplary shielding harness comprises first, second and the 3rd substrate 36,37 and 38, covers whole opening 20.Any with predetermined structure relatively install or positioning substrate simultaneously and the chamber radome keep the part that electrically contacts, all be suitable.
Structure shown in Fig. 2 A holds the combination of rigid conductive substrate, compliant conductive substrate or rigidity and flexible substrate.Three substrate modules comprise the structure stand 26 and 27 that is fit to be contained in the opening and links up basically with the whole periphery of opening as shown in the figure.Support integral body can have similar cross sectional shape.Support 26 and an embodiment of 27 are for having oblique angle metal extrusion shapes.Suitable metal includes but not limited to: tin-plated brass, other alloy, aluminium or steel.As selection, can on above-mentioned oblique angle, arrange the electrically conductive elastic band, thereby guaranteeing to have closerly electrically contacts between module carrier spare 26,27 and window periphery.Itself electrically contact and embed wherein shelf support 41, be used to limit window edge with the wall 14 of radome.
Usually, any conduction or the material that is endowed conductivity all are suitable bracket supports material or timbering materials.So, support can be solid material (homogeneous electric conducting material) or on non-conducting material the coating electrically conductive material form.It is that 1 millimeter thickness is suitable that conductive coating begins.Like this, shelf support 41 can apply the material of high conductivity, normally such as non-oxidizable materials such as tin.
When using or make up rigid conductive substrate or compliant conductive substrate, can use the substrate Fastener of Fig. 2 A shown type.Usually, use lapping plate 15 is pressed against each other frame member 26,27 or is secured on conductive substrate 36,37 and 38.Snap action points to the median surface of opening, and this plane parallel is in the EMI attenuating elements of just installing here, and snap action is by playing a role such as bolt 21 fixtures such as grade or securing member.Bolt 21 is arranged in the zone of window bracket supporting member 41, and forms complementary match surface such as screwed hole 22.
Under the situation of only using flexible substrate (as shield grid), can use other supporting structure 28 and 29 that is shown in Fig. 2 B.This structure has curved channel 46,47,48, at first holds the edge of flexible shielding grid.The flexible curled-edge 44 that is fit to be contained in passage 46,47,48 is wedged in the passage tightly, guarantees electrically contacting between shielding screen and support.It is in 5012041 the patent that this shield grid fastening structure also is disclosed in U.S. Patent number, it for this assignee all and refer to here as a reference.
Another kind of substrate installation method has been described in Fig. 2 C.In this embodiment, shield grid 36,37 and 38, perhaps other conductive substrate keeps being electrical contact with each other, and keeps and radome 17 electrically contacts by simple securing member and Fastener.At this moment, between the conduction lamination 50 that shield grid is sandwiched in successively and shielding wall 17 and shield grid 36,37 and 38 electrically contact.Also keep electrically contacting closely as long as produce, any that lapping plate 50 is fastened to the mode of shielding wall 17 is all suitable.This fastening means includes but not limited to screw thread 54, welding and frictional fit.
For keep be separated from each other between the contiguous conductive substrate apparent surface predetermined distance D 1 and D2, can use being fit to holding, anchoring or and the packing material 52 that cooperates of screw.
Another substrate installation method has been described in Fig. 2 D.This structure allows that independent mounting bracket 64,65 and 66 is on bracket leg bearing surface 61,62 and 63 respectively, and its medium-height trestle-area supported is arranged with inclination, step-like structure.Step support-area supported integrated molding each other constitutes single rack mounting structure 68, perhaps makes separately respectively and utilizes above-mentioned multiple chucking or bolt part to connect together.Similar, support 64,65 and 66 utilizes screw thread, bolt or other securing member 71 reversibly to be installed to the bracket supports surface separately.A notable feature of this installation constitution is to make independent support substrate install one by one, has made things convenient for like this from radome one side selected substrate is carried out installation, maintenance, replacement and cleaning.
Can use one or more conductive substrates that a plurality of conductive surfaces described here are provided.For example, when exemplary mounting structure held single conductive substrate easily, monolithic compliant conductive substrate can fold or arrange so that described surface to be provided.The application of this use single flexible conductive substrate can be imagined the situation in Fig. 2 A-2C, and wherein surface 36,37 and 38 is formed by the monolithic flexible substrate, snakelike passing (Serpenting through) installed part and filling substrate.Substrate is apart from details
Have been found that the multiple distance between shield grid can provide good fade performance.In some cases, the shield grid separating distance reaches 30 inches, but is generally 1/3 to 12 inch, is used to optimize the EMI shielding properties.Usually, the distance of separating first and second shield grids is 1.5 to 2 inches, and the distance of separating the second and the 3rd shield grid can provide good effect for 0.5 to 0.75 inch.In some cases and depend on target EMI frequency, should be not equal between other substrate apart from D2 apart from D1 between substrate ... the integral multiple of Dx.In an exemplary, the 3rd shield grid 38 arranges with respect to first and second shield grids 36,37, makes about but inaccurate half of between the second and the 3rd shield grid 37,38 distance of being defined as of distance between first and second shield grids 36,37.Although rely on the EMI frequency, the preferred maximum distance of separating the second and the 3rd shield grid 37,38 approximately is 2 inches.
As mentioned above, different referring among the present invention between three shield grids with non-integral multiple distance, when forming a resonant cavity with convenient first and second shield grids, the 3rd shield grid stops the propagation of resoance radiation.On the contrary, when the second and the 3rd shield grid formed a resonant cavity, first shield grid stopped the propagation of resoance radiation.Conductive substrate material details
Can use but be not limited to following polytype electric conducting material: gold, silver, bronze, copper, aluminium, stainless steel and combination thereof.The present inventor finds that determine, high relatively reflectivity (being conductance) material (for example bronze, copper and stainless steel) has higher fade performance as middle shield grid 37.
Other embodiment also is suitable as conductive substrate, includes but not limited to, by the composite material of rigidity that applies satisfactory electrical conductivity and optical clear metal or net grid coating or flexible and transparent structure (for example plastics or glass) formation.Electric conducting material can utilize flame-spraying, electro-deposition (as plasma spraying) or utilize other method to be coated onto on the matrix.Under the situation of lattice, this method allows to use the thick or thicker slightly optically transparent conductive coating of several dusts.As a result, these optically transparent materials have than supporting the better light transmission of shield grid certainly.Suitable optically transparent material is by the Pilkington United Kingdom Co., Ltd that is positioned at Helen Si street, England, and the storm wind safety system company of the Troy by being positioned at Ohio, USA (OH) provides.
As mentioned above, substrate can utilize slab construction, curved tabs structural configuration, perhaps uses plane and curved configuration simultaneously.For example, Fig. 2 A has described a common flat substrate 37,38, and its periphery constitutes the knuckle part 39 and 40 that makes progress respectively.These knuckle districts that can select to provide can further promote electrically contacting between substrate and shelf support 41.The shield grid substrate details
Here shield grid is as conductive substrate, and several different mesh order numbers are suitable.The mesh figure can be defined as on 1 inch length the number along a given straight line or orthogonal direction opening.As mentioned above, the mesh of different shield grids varies in size.Usually, mesh order number has good attenuation results between 14 (slightly) and 60 (carefully).In one embodiment, need the decay maximization and place little emphasis on and minimize moire pattern, this moment, first shield grid 36 can have thick relatively mesh figure, and secondary shielding grid 37 can have thin relatively mesh figure, and innermost shield grid 38 has the thinnest mesh figure in three shield grids., be the attenuating that need to obtain, can shield grid be installed according to any order.Use the advantage of shield grid to be to have in many cases the described assembly such as Fig. 2 B Fig. 2 D, wherein shield grid can be dismantled separately, with convenient for cleaning, maintenance with change.
Except use had three shield grids of different mesh figures, three shield grids also can oriented arrangement, so that each the skew certain angle in the electric wire array of the electric wire array of each shield grid and other two shield grids.Deviation angle can be obtained optimum performance in time between 15 to 45 degree.This arranged offset can minimize net pattern effect.
Shield grid can form multiple different structure.Suitable shield grid comprises the conductive strand that is arranged as triangle, quadrangle or other polygon mode.And shield grid electric wire actual diameter can be different, and thick line has higher rigidity usually.
Except braided wire cloth, other but the structure that is not limited to all is suitable such as grid matrix, open grid, perforated sheets and vacuum moulding machine to the conductive grids on the non-metal base (as the glass plate that is using on the window).Usually the deposition continuous film eats away unnecessary metal again.When the metallization pattern on the use transparent substrate, the rigidity on surface relies on width and the thickness that deposits to on-chip grid metalwork.The shielding properties example
With reference to Fig. 3 and 4, this graphical representation is at three plane shield grid designs, the biplane shield grid design with 1 and 3/4 inch width, the biplane shield grid design with 3/4 inch interval and the design of single shield grid, improved EMI shielding properties in 1GHz arrives the 11GHz frequency.
Fig. 3 and Fig. 4 represent the excellent shielding properties of three shield grid systems of the present invention, wherein can obtain 100dB or above decay.The excellent shielding properties of three shield grid systems is to have reduced the result of EM resonance, wherein be higher than relatively being also illustrated among the figure of 10MHz double shield grating system.For example, when using the double shield grid, the EMI fade performance descends when certain original frequency and resonance/resonance frequency, for example relatively at resonance point (the A point among Fig. 3) and its 2 overtones band 6.6GHz (the some B among Fig. 4) of frequency 3.3GHz.Other resonance point is labeled as C, D and E in above-mentioned two figure.Three shield grid systems do not exist tangible resonance or sympathetic response effect under said frequencies.Like this, the present invention has not only improved overall shielding character, has also optimized the shielding properties under selected frequency.
Can use 4 or the shield grid that more has an appropriate intervals to expand said method.Non-parallel substrate
Referring now to Fig. 5 A, 5B, 5C, provide end view according to other design of the present invention.As mentioned above, arrange three shield grids EMI that decays., these designs also adopt non-parallel cavity to come the surface further to promote the non-complete reflection mutually of the EMI of cavity qualification.Shown in Fig. 5 A, a kind of mode that influences non-parallel surfaces is inwardly pulling or laterally moves the part that the first and the 3rd shield grid 36,38 forms cavity 15 inwalls 19.A not too protruding side shield grid structure is illustrated in Fig. 5 B.As a kind of selection, the center also can outwards be moved, thereby makes the inwall indent, and in other words, the first and the 3rd shield grid 36,38 can be by the design structure of basic bending, so that each cambered surface partly is positioned at opposite direction.As a kind of selection, shown in Fig. 5 C, two in three shield grids are arranged as ' V ' shape structure.
At last, the first and the 3rd shield grid can have the difform surface that faces with each other, for example form the surface of indent more by locating first shield grid 36 from central cross or outside skew, inwardly or to off-centring formation more protrusion is surperficial to locate the 3rd shield grid 38 simultaneously.Another kind of suitable shield grid structure comprises two the side shield grids 36,38 in location, utilizes intershield grid 37 to cut apart the acute angle that (perhaps five equilibrium or not five equilibrium) forms effectively between two side shield grids, forms ' V ' shape.
In a kind of method of making non-parallel housing surface, one end of electric wire is connected with the center 39 of first shield grid 36, and the other end connects with the corresponding center 39 of the 3rd shield grid 38, thereby inwardly spur or laterally move outermost shield grid and point to the intershield grid, form the part inwall 19 of protruding cavity.The another kind of method of making the curved surface housing surface is the shape that at first the rigid conductive made is become to need, and re-uses and handles above-mentioned ' substrate material details ' described plane conductive substrate same procedure these on-plane surfaces are carried out metalized.
The same with former design, the distance between any two adjacent substrate should be not equal to the integral multiple of respective distances between other shield grid.
Fig. 6 and the pulling design of 7 contrasts, three shield grid centers, three plane shield grid design and the designs of single shield grid, the EMI pad value of corresponding different frequency.Comment 14 * 18 expression mesh order numbers among the figure.
Fig. 6 and 7 illustrates that clearly the three shield grid centers attenuation characteristic of pulling design under definite resonance frequency is better than three plane shield grids designs (seeing a F, G, H).For example when frequency 7.9GHz (G point among Fig. 7), the reduction (being reduced to 31dB) of fade performance appears in the resonance that the parallel design of three shield grids causes owing to distance between inner shield grid 36 and external shield grid 38.Comparatively speaking, the pad value that provides of center pulling structure surpasses 50dB.
, in Fig. 7, under some higher frequencies, three shield grid plan-parallel structures show better EMI fade performance (except resonance frequency) than center pulling structure.
Because the excellent attenuation characteristic of three shield grid embodiments is to have prevented the resonance of input ray and the result of sympathetic response, therefore non-parallel being arranged in juxtaposition (for example ' center pulling ') design also can be used for double shield grid structure, obtains some improvement.The suitable selection of shield grid spacing and shape can be guaranteed the suitable shielding under characteristic frequency.And non-parallel shield grid can be used for making up the design of four or more a plurality of shield grids.
Special value of the present invention is to eliminate or remove resonance point from interested frequency.Operation of the present invention can be described as a kind of like this method of the electromagnetic radiation that decays, and at first makes electromagnetic radiation shine the first conductive plane substrate, the first that causes electromagnetic radiation by this substrate and the electromagnetic radiation second portion by first substrate; Make the electromagnetic radiation that passes through enter one then and prevent that these electromagnetic radiations that pass through from producing the device of resonance frequency.
Originally prevent that resonance device from comprising the cavity that an additional conductive planar substrates that utilizes the first conductive plane substrate and a plurality of vicinity first conductive plane substrate to be arranged in juxtaposition constitutes.Wherein, additional substrate is along arranging with electromagnetic radiation initial point rightabout.
In a word, the invention provides a kind of best method that shields substrate and a kind of EMI of optimization shielding properties that serves many purposes.Therefore the inventive method and substrate can be used for various purposes, can and separate structure as radome wall structure, ceiling structure, window structure, and army's industry that also can be used for electronic product manufacturing, motor vehicle manufacturing and relate to anti-eavesdrop is used.
Therefore, can use typical conductive substrate (aforesaid shield grid and metallization grid array) and atypia conductive substrate, these atypia conductive substrates include but not limited to be arranged as such as non-rectangle forms such as triangle, honeycombed and circles, and wherein these construction units can with one heart or same size be arranged and co-planar arrangement constitutes a continuous substrate sheet.By selecting suitable material, this method and substrate can be any one element of attempting the additional transparent and saturating sound of screen.
Describe although the present invention is the details according to embodiment shown in of the present invention, these details are not used in restriction appended claims restricted portion.For example and as previously mentioned, be the EMI fade performance that obtains at target frequency the best, two, three or can be arranged opposite to each other more than three substrate, and the surface of revising or making them separately.
Claims (43)
1. EMI attenuating device is characterized in that it comprises:
A) spatially contiguous one second conductive component and one first first conductive component that distance is arranged at interval with it; With
B) spatially contiguous described second conductive component and the 3rd conductive component that second distance is arranged at interval with it.
2. device as claimed in claim 1 is characterized in that, described first distance is equal to each other with described second distance.
3. device as claimed in claim 1 is characterized in that, described first distance differs from one another with described second distance.
4. device as claimed in claim 1 is characterized in that described neighbouring surface is parallel to each other.
5. device as claimed in claim 1 is characterized in that, at least two described neighbouring surfaces are not parallel each other.
6. device as claimed in claim 1 is characterized in that, also comprises one the 4th planar member, and it is close to described the 3rd planar member and arranges away from first planar member.
7. device as claimed in claim 1 is characterized in that described conductive component comprises the material that is arranged as rectangular array.
8. device as claimed in claim 1 is characterized in that, describedly decays to about 90 to 120dB.
9. device as claimed in claim 1 is characterized in that, described planar member is to have a mesh-structured shield grid, and each is described mesh-structuredly to be grid and to have certain mesh order number.
10. device as claimed in claim 9 is characterized in that, the mesh order number of described first conductive component is less than the mesh order number of described second conductive component.
11. device as claimed in claim 10 is characterized in that, the mesh order number of described second conductive component is less than the mesh order number of described the 3rd conductive component.
12. device as claimed in claim 10 is characterized in that, the mesh order number of described three conductive component is between per inch 8 to 200.
13. device as claimed in claim 1 is characterized in that, the described distance of separating described first surface and described second surface is between 1/3 inch to 30 inches.
14. device as claimed in claim 1 is characterized in that, the described distance of separating described first surface and described second surface is between 1/3 inch to 12 inches.
15. device as claimed in claim 1 is characterized in that, described electric conducting material is optically transparent.
16. device as claimed in claim 1 is characterized in that, described electric conducting material is metallized optical transparent substrate.
17. device as claimed in claim 16 is characterized in that, described optical transparent substrate is selected from following group, and this group comprises glass, plastics, braiding structure material, grid material or their combination.
18. device as claimed in claim 1 is characterized in that, described conductive component has and is lower than 12 ohm every square resistance.
19. device as claimed in claim 1 is characterized in that, all adjacent plane spares are all not parallel each other.
20. device as claimed in claim 1 is characterized in that, selects described first distance and described second distance, so that the EMI decay maximization under predetermined EMI frequency.
21. device as claimed in claim 1 is characterized in that, selects described first distance to obtain first Reduction Level under specific EMI frequency, selects described second distance to come the EMI under the described characteristic frequency is carried out additional attenuation.
22. device as claimed in claim 1 is characterized in that, selects described first distance and described second distance, so that the decay of the EMI on scheduled frequency range maximization.
23. the method for the electromagnetic radiation that decays may further comprise the steps: make radiation enter in a plurality of resonant cavities with different size and different resonant frequencies, so that the resonance of the radiation in a particular cavity is stoped by described other resonant cavity.
24. method as claimed in claim 23 is characterized in that, described resonant cavity comprises:
A) one first conductive plane;
B) second conductive plane that the described first surface of vicinity is arranged is so that form first restriceted envelope of first distance that comprises separation described first and described second surface; And
C) described second surface of vicinity and the 3rd conductive plane arranged away from first surface comprise and separate described second and second restriceted envelope of the second distance on described the 3rd surface so that form.
25. method as claimed in claim 23 is characterized in that, also comprises described the 3rd surface of vicinity and the 4th conductive surface of arranging away from described first surface, so that form one the 3rd restriceted envelope.
26. device as claimed in claim 23 is characterized in that, described first distance differs from one another with described second distance.
27. device as claimed in claim 23 is characterized in that, described surface is the conductive shield grid.
28. device as claimed in claim 23 is characterized in that, described surface is optically transparent conductive surface.
29. a window that uses with the EMI radome is characterized in that this window comprises at least two conductive surfaces, and any two neighbouring surfaces are not parallel.
30. window as claimed in claim 29 is characterized in that, also comprises:
A) first conductive surface that is connected with the conductive window support;
B) second conductive surface arranged of the described first surface on described support of vicinity; And
C) described second surface of vicinity and the 3rd conductive surface arranged away from the described first surface on the described support.
31. window as claimed in claim 30 is characterized in that, also comprises described the 3rd surface of vicinity and the 4th conductive surface of arranging away from described first surface.
32. window as claimed in claim 29 is characterized in that, at least one described surface is an on-plane surface.
33. window as claimed in claim 29 is characterized in that, described surface is a shield grid.
34. window as claimed in claim 29 is characterized in that, described surface is optically transparent.
35. the method for the electromagnetic radiation that decays comprises:
A) make electromagnetic radiation shine the first conductive plane substrate, to such an extent as to the first of electromagnetic radiation does not pass through described substrate, and the second portion of electromagnetic radiation is by described substrate;
B) make the electromagnetic radiation that has passed through enter one and be used for reducing the device that the described ray that passes through further passes through.
36. method as claimed in claim 35, it is characterized in that, described minimizing device comprises the zone that is made of a plurality of additional conductive planar substrates that are arranged in juxtaposition along the straight line perpendicular to first substrate plane, and wherein said additional conductive planar substrates is along arranging with electromagnetic radiation initial point rightabout.
37. method as claimed in claim 36 is characterized in that, at least one described additional straight substrate is not parallel to first planar substrates.
38. method as claimed in claim 35 is characterized in that, described substrate is a shield grid.
39. method as claimed in claim 35 is characterized in that, described substrate is optically transparent.
40. the device of the electromagnetic interference that decays is characterized in that, it comprises:
A. one first restriceted envelope has a plurality of walls that are made of first and second conductive shielding parts;
B. one second restriceted envelope has by described second conductive shielding part and one the 3rd a plurality of walls that conductive shielding part constitutes; And
C. locate the device of first, second and the 3rd shielding part, wherein be different from corresponding conllinear distance between the described second and the 3rd conductive shielding part adjacent wall in the distance between the described first and second conductive shielding part adjacent wall.
41. an EMI attenuating device is characterized in that, it comprises two conductive surfaces, and wherein said surface is an average distance separately, and described average distance is chosen as and obtains the maximum attenuation effect under preset frequency.
42. EMI attenuating device as claimed in claim 41, it is characterized in that, described two conductive surfaces have molded non-planar, and described surface average distance separately, and described molded non-planar and described average distance are chosen as and obtain the maximum attenuation effect under preset frequency.
43. EMI attenuating device as claimed in claim 41 is characterized in that, described at least one described surface also comprises shield grid.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1999/012383 WO2001006822A1 (en) | 1999-07-19 | 1999-07-19 | A method for attenuating electromagnetic interference, an electromagnetic interference attenuation device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1362006A true CN1362006A (en) | 2002-07-31 |
Family
ID=22272890
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99816809.2A Pending CN1362006A (en) | 1999-07-19 | 1999-07-19 | A method for attenuating electromagnetic interference, an electromagnetic interference attenuation device |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP2003507903A (en) |
| CN (1) | CN1362006A (en) |
| AU (1) | AU5080399A (en) |
| GB (1) | GB2370160B (en) |
| WO (1) | WO2001006822A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113277004A (en) * | 2021-05-19 | 2021-08-20 | 无锡市申锡船舶设备有限公司 | Electromagnetic heating shielding window for ship |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE202012002920U1 (en) | 2012-03-21 | 2012-04-24 | Rolf Espe | Coupling elements for floor panels that allow a vertical coupling and unlocking without damage |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3531577A (en) * | 1968-07-10 | 1970-09-29 | Sprague Electric Co | Door for a shielded enclosure |
| US3982058A (en) * | 1975-05-13 | 1976-09-21 | The United States Of America As Represented By The Secretary Of The Navy | Magnetic and electric field shielding of computer components from lightning |
| EP0322720A3 (en) * | 1987-12-25 | 1990-01-17 | Asahi Glass Company Ltd. | Electromagnetic wave shielding transparent body |
-
1999
- 1999-07-19 GB GB0200301A patent/GB2370160B/en not_active Expired - Lifetime
- 1999-07-19 AU AU50803/99A patent/AU5080399A/en not_active Abandoned
- 1999-07-19 WO PCT/US1999/012383 patent/WO2001006822A1/en active Application Filing
- 1999-07-19 CN CN99816809.2A patent/CN1362006A/en active Pending
- 1999-07-19 JP JP2001519136A patent/JP2003507903A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113277004A (en) * | 2021-05-19 | 2021-08-20 | 无锡市申锡船舶设备有限公司 | Electromagnetic heating shielding window for ship |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2001006822A1 (en) | 2001-01-25 |
| GB0200301D0 (en) | 2002-02-20 |
| AU5080399A (en) | 2001-02-05 |
| GB2370160B (en) | 2003-11-05 |
| GB2370160A (en) | 2002-06-19 |
| JP2003507903A (en) | 2003-02-25 |
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