Patent Description:
Various methods and devices are used to decrease unintentional radiated emissions from electronic devices. Localized shielding on a printed circuit board ("PCB"), filters, bandstop filters, absorbing materials, and customized PCB layouts, are techniques commonly implemented to decrease radiated emissions. With regard to shielding enclosures, the purpose of the enclosure is to contain the energy of the radiated emissions within the enclosure, but any opening within the enclosure can result in electromagnetic field leakage. For example, in optical transceivers, an opening is required for the optical fibers to connect with their modules resulting in electromagnetic field leakage. The sizes of such openings may also be resonant at one or more frequencies of interest, thereby amplifying the overall radiated emission level at some frequencies. It is also quite common that a select few radiated emissions harmonics are significantly higher than others and in order to suppress them to an acceptable level, the shielding of the enclosure needs to be improved.

Using known enclosures and methods of shielding, it is not possible to increase the shielding effectiveness at just one frequency. Instead, the entire enclosure must be redesigned. There are many drawbacks to a redesign, in addition to the time and cost needed to redesign. It may be difficult to achieve the desired shielding without having an impact on thermal performance, serviceability and cost. This is particularly true when the highest harmonic that needs to be suppressed is within the highest of frequencies. Indeed, increasing the shielding performance of the enclosure to achieve the desired high frequency shielding effectiveness considering all other design constraints (mechanical, thermal, need for connector apertures, cost, and the like) may not be possible in certain circumstances. <CIT>describes a substantially plastic digital video poster having a plurality of superposed layers of different compositions and characteristics that combine to form a pixilated addressable flexible display with an embedded functionality. The plastic digital video poster comprises a top panel assembly and bottom panel assembly joined by aligning conductor patterns of a supplementary first conductive layer to that of a first conductive layer and bonding the assemblies with adhesive layer. <CIT> refers to a shielding structure, which is arranged so as to sufficiently prevent disturbing interferences from itself and other devices, such that non- desired communication waves are not intermixed or emitted. <CIT>elates to a method of manufacturing a conductive sheet, in which a wire material in the form of a mesh pattern is formed on a substrate. <CIT>elates to an electromagnetic wave shielding film for a flexible printed circuit board (FPCB), and a manufacturing method therefor. <CIT> refers to a radar absorbing material comprising multiple layers, wherein the material includes a substrate disposed thereon antenna elements. The broad handling of the device is carried out by multi-layering concepts in which different size antenna patterns are multi-layered with each layer designed to absorb frequencies in s specified range.

An electromagnetic interference ("EMI") sheet attenuator according to an aspect of this disclosure includes a planar conductive layer, a first flexible substrate and a second flexible substrate. The first flexible substrate overlies the planar conductive layer and includes a conductive pattern on a surface of the first flexible substrate. The second flexible substrate overlies the first flexible substrate and includes a further conductive pattern. The conductive patterns on the second flexible substrate are aligned with the conductive patterns on the first flexible substrate. Multiple flexibles substrates with conductive patterns on their surfaces can also be overlaid on each others.

In one example, the first and second printed patterns of the EMI sheet attenuator are comprised of a conductive ink material.

The first and second flexible substrates each further include respective top and bottom surfaces. The conductive patterns are positioned on the top surfaces of the first substrate and the top surface of the second substrate, respectively. The planar conductive layer may also further include a top surface and a bottom surface, wherein the bottom surface of the first substrate is joined to the top surface of the planar conductive layer. An adhesive layer may join the first substrate and the metal layer together.

In another example, the metal layer may be comprised of a metal sheet of material, or may be a substrate with a metal material coated thereon.

In still another example, the first flexible substrate of the EMI sheet is comprised of a paper material or a transparent plastic material.

In yet another example, the first flexible substrate and the second flexible substrate may be comprised of a dielectric material.

In still another example, the EMI sheet is configured to reflect wave impedance in both a near field and a far field.

According to another aspect of the disclosure, an enclosure for an electronic device includes at least a first wall and a second wall joined together at their respective ends. The first wall may include a first interior surface and the second wall may include a second interior surface. A first electromagnetic ("EMI") sheet attenuator may be positioned at the first interior surface. A second EMI sheet attenuator may be positioned on the second interior surface. Each of the first and second EMI sheet attenuators include a planar conductive layer, a first flexible substrate and a second flexible substrate. The first flexible substrate overlies the planar conductive layer and includes a pattern on a surface of the first flexible substrate. The second flexible substrate overlies the first flexible substrate and also includes the conductive pattern. The conductive pattern on the second flexible substrate is aligned with the conductive pattern on the first flexible substrate.

In one example, one of the wall surfaces may further include an opening through which the electronic device extends.

In another example, the first conductive patterns and second conductive patterns of each of the first and second EMI sheet attenuators are periodic structures.

In yet another example, the conductive patterns on the first and second flexible substrates are periodic structures.

According to still another example, not in accordance with the claimed invention, the conductive patterns on the first and second conductive substrates are different.

In one example, the enclosure further includes a third wall, a fourth wall, a fifth wall, and a sixth wall that together with the first and second walls extend about all sides of the electronic device. A third EMI sheet attenuator may be attached to the third wall. A fourth EMI sheet attenuator may be attached to the fourth wall. A fifth EMI sheet attenuator may be attached to the fifth wall. A sixth EMI sheet attenuator may be attached to the sixth wall.

In another example, the conductive patterns disposed at the first and second flexible substrates are comprised of conductive ink material.

In still another example, the planar conductive layers of the respective first and second flexible substrates further include a top surface and a bottom surface, and wherein each of the bottom surfaces of the first substrates of the first and second flexible substrates is joined to the top surface of the planar conductive layer.

In another example, an adhesive layer joins the first flexible substrate and the planar conductive layer together.

In a last example, the first EMI sheet is configured to reflect wave impedance in both a near field and a far field.

It is to be noted that the features of the above-described arrangements are not exclusive to each other, and that any one of such features and arrangements can be combined with one or more of the other features and arrangements.

A more complete appreciation of the subject matter of the present disclosure may be realized by reference to the following detailed description and the accompanying drawings, in which:.

Aspects of the disclosure relate to methods and devices for minimizing electromagnetic interference caused by electronic devices. In particular, a multi-layer electromagnetic interference ("EMI") sheet attenuator is disclosed that can suppress an impinging wave and wave frequencies generated by an electronic device without requiring further modifications to the design of the shielding enclosure, the printed circuit board, or other parts of the system. It is possible to reduce the radiated emissions at certain frequencies by depositing EMI sheet attenuators with patterned structures to enclosure walls used to directly or indirectly house a device to attenuate the radiofrequency ("RF") energy inside the enclosure. These patterned structures have a frequency dependent impedance which depends on their geometry. By designing the geometry with an impedance close to the impinging wave impedance, reflections from the enclosure walls can be attenuated and leakage from the enclosure reduced.

<FIG> is an example multi-layer EMI sheet attenuator <NUM> according to aspects of the disclosure. The EMI sheet attenuator <NUM> can be used to reduce radiated emissions from electronic devices and the like. In particular, a patterned structure <NUM> on the EMI sheet attenuator <NUM> can attenuate the radiofrequency energy that radiates from an electronic device or the like. EMI sheet attenuator <NUM> is shown as being planar, but sheet attenuator <NUM> may also take on other configurations. EMI sheet attenuator <NUM> may have an overall thickness ranging from less than <NUM> to a few mm. In some examples, the overall thickness may be less than <NUM> so as to maintain an EMI sheet attenuator <NUM> that is overall thin and flexible. In other examples, the overall thickness may be greater than <NUM> or significantly less than <NUM>. In some examples, the thickness may be greater than <NUM> or significantly less than <NUM>. Due to the thickness, EMI sheet attenuator <NUM> can be overall thin and flexible.

A patterned structure may be provided on the first substrate layer <NUM> that is designed to match any desired wave impedance or frequency, such as the impedance of the wave to be emitted by an electronic device. Patterned structure <NUM> on EMI sheet attenuator <NUM> may include multiple rows of repeating patterns. For example, EMI sheet attenuator <NUM> includes first and second rows <NUM>, <NUM> of sets of patterned triangles or eight sets of patterned triangles. Each set <NUM> of triangles includes a lower triangle <NUM> having its hypotenuse <NUM> facing the hypotenuse <NUM> of a directly adjacent upper triangle <NUM>. The upper triangle <NUM> and lower triangles <NUM> may be spaced apart from one another to form a pattern. Four identical sets of patterned triangles may be provided in first row <NUM> and four identical sets of patterned triangles may also be provided in second row <NUM>. As will be discussed below, patterned structure <NUM> includes multiple sets of triangles formed on individual layers of the multi-layer EMI sheet attenuator <NUM> that align with one another to form the patterned structure <NUM> of EMI sheet attenuator <NUM>. It is to be appreciated that in the present example, patterned structure is a periodic structure, but in other examples, the patterned structure may not be a periodic structure.

EMI sheet attenuator <NUM> includes multiple layers attached together. As shown, for example, in <FIG>, a cross sectional view taken across line A-A of <FIG>, the EMI sheet attenuator <NUM> includes at least three primary layers: a conductive layer <NUM>, a first substrate layer <NUM> with a patterned structure 110A, and a second substrate layer <NUM> with a patterned structure 110B. The three layers may be joined together by adhesive layers <NUM>,<NUM>. In an embodiment not in accordance with the claimed invention, the conductive layer <NUM> can be optional if the sheet attenuator structure has to be applied onto a metal surface or conductive surface.

With reference to <FIG>, an exploded view of <FIG> (but without illustration of intermediate adhesive layers <NUM>,<NUM> for ease of discussion), conductive layer <NUM> may be a continuous and planar layer. Conductive layer <NUM> may be a sheet of metal material or may be a substrate with a conductive layer disposed at a surface of the substrate. The conductive material may be a conductive metal including, for example, copper, iron, aluminum, tantalum, silver, brass, alloys, graphene, graphite, carbon based materials and combinations thereof. When conductive layer <NUM> is a coated substrate, conductive layer can be manufactured using various methods, including sputtering a metallic coating onto a substrate, inkjet printing, chemical and physical vapor deposition, and the like. In other examples, conductive layer <NUM> may be a substrate with a patterned metal layer on a surface of the substrate. Conductive layer <NUM> may be a thin metal layer that is only a few microns thick, and in some examples ranging from <NUM> to a few millimeters thick.

First substrate layer <NUM> overlies conductive layer <NUM>, and may also be a continuous and planar layer. First substrate layer <NUM> may be formed from a dielectric material or combination of dielectric materials and/or other materials, such as, for example, plastic or paper. Examples of plastic material may further include vinyl, polyester-based films, HDPE, and polypropylene. First substrate layer may be <NUM> microns thick, and in some examples ranging from few tens of microns to a few millimeters, but in general no greater than <NUM> thick. Due to the relatively thin substrate layers <NUM>, <NUM>, the entire layered structure may be flexible. In the example shown, first substrate layer <NUM> is a transparent plastic material.

A patterned structure is provided on the first substrate layer <NUM> that is designed to match any desired wave impedance or frequency, such as the impedance of an impinging wave emitted by an electronic device. For example, with reference to <FIG> and as noted above, patterned structure 110A may be a series of repeating triangle patterns extending across the sheet. EMI sheet attenuator <NUM> may include first and second rows 102A, 104A of sets of patterned triangles or eight sets of patterned triangles. Each set of triangles includes a lower triangle 106A having its hypotenuse 107A facing the hypotenuse 109A of a directly adjacent upper triangle 108A. Upper triangle 108A and lower triangle 106A may be spaced apart from one another to form a single pattern, which may then be repeated across each of first and second rows 102A, 104A.

In one example, the patterned structure is printed on the first substrate layer <NUM> using conductive ink. The conductive ink may be composed of graphite, silver and/or other conductive materials infused into ink. The ink may be printed onto the first substrate layer <NUM> using known methods and based on the material forming the substrate layer <NUM>. For example, when first substrate layer <NUM> includes or is made from a plastic material, the conductive ink can be printed onto the first substrate layer using an inkjet printer or a method of printing or deposition that does not generate heat that would melt a plastic substrate. Alternatively, when the substrate is not heat sensitive, such as a paper substrate, alternative forms of printing, such as use of a laser printer, can be implemented to print the conductive ink onto the first substrate layer <NUM>. The patterned structures <NUM> may be provided onto the first substrate layer <NUM> using other known methods, including lamination, etching, and the like.

The second substrate layer <NUM> may be identical to or different than first substrate layer <NUM>. In one example, as shown in <FIG>, second substrate layer <NUM> may be a transparent plastic material that is identical in all respects to the first substrate layer <NUM>. The material comprising second substrate layer may be a same dielectric material and thickness as the first substrate layer <NUM>.

In this example, the patterned structure 110B of second substrate layer <NUM> is also formed from a conductive ink printed on the first substrate layer <NUM>. Patterned structure 110B is identical to patterned structure 110A of first substrate layer <NUM> and includes four sets of triangles. Patterned structure 110B is positioned on second substrate layer <NUM> so that it is aligned with patterned structure 110A on first substrate layer <NUM>. In other examples, second substrate layer <NUM> can differ from the first substrate layer <NUM>, in terms of insulating properties, thickness of the material, the material comprising second substrate layer <NUM>, in a case not in accordance with the claimed invention the patterned structure on second substrate layer <NUM>, and any other desired features.

A protective layer (not shown) can optionally be provided on top surface of second substrate layer <NUM>. Protective layer can overlie patterned structure 110B to protect patterned structure 110B from being damaged. The protective layer can be made of another layer of plastic or substrate material or may be a coating applied over the outermost patterned structure 110B.

Conductive layer <NUM>, first substrate layer <NUM> and second substrate layer <NUM> may be joined together to form EMI sheet attenuator <NUM>. As shown, the bottom surface <NUM> of the first substrate layer <NUM> may be joined to the top surface <NUM> of the conductive layer <NUM>. Similarly, bottom surface <NUM> of second substrate layer <NUM> may be joined to the top surface of first substrate <NUM>. Top surface <NUM> of second substrate layer <NUM> can remain exposed. It is to be noted that in a configuration not in accordance with the claimed invention the conductive layer <NUM> can be optional if the assembled and layered EMI sheet structure has to be applied to a metal surface, such as with use of an adhesive.

In one example, an adhesive may be used to attach each of the conductive layer <NUM>, first substrate layer <NUM>, and second substrate layer <NUM> together to form EMI sheet attenuator <NUM>. Example adhesives can include polymer adhesives, such as epoxies, silicones, acrylics, polyimides, cyanate esters, and various thermoplastic materials. The adhesive may be uniformly applied across one or both surfaces that are joined together. For example, an adhesive may be applied between top surface <NUM> of conductive layer <NUM> and bottom surface <NUM> of first substrate layer <NUM>, as well as between top surface <NUM> of first substrate layer <NUM> and bottom surface <NUM> of second substrate layer <NUM>. An adhesive may also be applied to bottom surface <NUM> of conductive layer <NUM> to attach EMI sheet attenuator <NUM> to another surface. In other examples, alternative methods of joinder may be utilized, such as pressing the layers together, mechanical fasteners, and any other methods of joining each of the conductive layer <NUM>, first substrate layer <NUM>, and second substrate layer <NUM>. Additionally, different methods for joining the layers may be utilized in the formation of EMI sheet attenuator <NUM>. For example, second first substrate layer <NUM> may be joined to conductive layer <NUM> using one method of joinder and the second substrate layer <NUM> may be joined to first substrate layer <NUM> by a different method.

When joined together, the aligned patterned structures 110A, 110B form the patterned structure <NUM> of EMI sheet attenuator <NUM>. As shown in <FIG>, patterned structure <NUM> becomes a stacked and three-dimensional structure that includes a height H, a width W, and a length L. Patterned structure <NUM> can help to block impinging waves from an electronic device or the like, as will be discussed in more detail.

It is to be appreciated that any desired patterned structure may be provided on the EMI sheet attenuator. Radiated emissions can be attenuated by EMI Sheet attenuators by designing the geometry of the patterned structure with an impedance close to the imping wave impedance. This allows for the design of a specific patterned structure to target a specific frequency. <FIG> illustrates an alternative multiple layer EMI sheet attenuator <NUM>. The EMI sheet attenuator <NUM> may be manufactured from the same or similar materials as EMI sheet attenuator <NUM>, as discussed above. With reference to <FIG>, a cross-sectional view of EMI sheet attenuator <NUM>, EMI sheet attenuator <NUM> includes four primary layers: conductive layer <NUM>, first substrate layer <NUM>, second substrate layer <NUM>, and third substrate layer <NUM>. Each of the layers may be attached together using adhesive layers <NUM>, <NUM>, and <NUM>. An additional adhesive layer <NUM> may be applied to conductive layer <NUM> to join the EMI sheet attenuator <NUM> to another structure.

EMI sheet attenuator <NUM> includes a patterned structure <NUM>. In this example, patterned structure <NUM> includes a first row <NUM>, a second row <NUM>, and a third row <NUM> of sets of patterned squares. Each set <NUM> of patterned squares includes three concentric squares. As shown, a first outer square <NUM>, a second intermediate square <NUM>, and a third interior square <NUM> respectively decrease in size to provide for a set <NUM> of concentric squares. Four identical sets of patterned and concentric squares may be provided in each of first row <NUM>, second row <NUM>, and third row <NUM>. As in the previous example, patterned structure <NUM> will be comprised of multiple sets of patterned squares formed on individual layers of the multi-layer EMI sheet attenuator <NUM> that align with one another to form the patterned structure <NUM> of EMI sheet attenuator <NUM>.

<FIG> is an exploded view of <FIG> (without adhesive layers <NUM>, <NUM>, <NUM>, <NUM> for ease of discussion). Conductive layer <NUM> may be a planar metal sheet or a layer of metallic material provided on a substrate, as previously disclosed above. Each of the first substrate layer <NUM>, second substrate layer <NUM>, and third substrate layer <NUM> may be identical to the substrate layers discussed above and differ only with regard to the patterned structures provided on each of the substrate layers, as well as the location of the patterned structure.

Patterned structure 210A of first substrate layer <NUM> may include a first row 202A, a second row 204A, and a third row 206A of sets of patterned squares. Each set of patterned squares includes three concentric squares. As shown, a first outer square 258A, a second intermediate square 260A, and a third interior square 262A respectively decrease in size to provide for a set 218A of patterned and concentric squares. Four identical sets of patterned and concentric squares may be provided in each of first row 202A, second row 204A, and third row 206A. The same patterned structures 210B and 210C may be printed on respective second substrate layer <NUM> and third substrate layer <NUM>. As shown in <FIG>, each of the patterned structures 210A, 210B, 210C may be aligned with one another to form the overall patterned structure <NUM> of EMI sheet attenuator <NUM>. In this view, patterned structure <NUM> will be a three-dimensional structure having a height H, width W, and length L.

An EMI sheet attenuator according to aspects of the disclosure may be used to reduce radiated emission levels generated by an electronic device within an enclosure. Such EMI sheet attenuator can be provided onto one or more walls of an enclosure for an electronic device, including directly on a housing of an electronic device, or an enclosure built to contain electronic device. A cross-section of an example enclosure <NUM> with an electronic device <NUM> within the enclosure <NUM> is shown in <FIG>. In this example, the enclosure includes six sides: top side 306A, bottom side 306B, right side 306C, left side 306D, back 306E and front (not shown in the cross-section). A portion of electronic device <NUM> is housed within enclosure <NUM>, while another portion of electronic device <NUM> extends through an aperture <NUM> in right side wall surface 306C of enclosure <NUM> so that the electronic device <NUM> is exposed outside of enclosure <NUM>. In other examples, enclosure <NUM> may be fully enclosed to include all six sides of electronic device, or enclosure <NUM> may only partially enclose an electronic device, such that the enclosure includes less than six sides.

To minimize radiated emissions, an EMI sheet attenuator may be applied to one or more surfaces on an enclosure. For purposes of discussion, reference will be made to use of EMI sheet attenuator <NUM> within an enclosure to reduce radiated emissions. However, sheet attenuator <NUM> or other sheet attenuators formed according to aspects of the disclosure may be utilized.

In one example, EMI sheet attenuators 100A, 100B, 100C, 100D, 100E, and 100F (not shown), which are each individually identical to the pattern and characteristics of EMI sheet attenuator <NUM>, are applied to the respective interior top surface <NUM>, bottom surface <NUM>, opposed edge surfaces <NUM>, <NUM>, rear surface <NUM>, and front surface (not shown in the cross-sectional view). As shown, EMI sheet attenuators 100A, 100B, 100C, 100D, 100E, and 100F are applied to the entirety of the respective surfaces to which they are applied, but in other examples, one or more of EMI sheet attenuators 100A, 100B, 100C, 100D, 100E, and 100F may be applied to only a portion of one or more surfaces to which it is applied. An EMI sheet attenuator may also be applied directly to a housing of the electronic device <NUM> within enclosure <NUM>. For ease of illustration, the patterns <NUM> are not shown on the interior surface of enclosure <NUM>, but it is to be understood that in this example, EMI sheet attenuators 100A, 100B, 100C, 100D, 100E, and 100F, each having the pattern shown in <FIG>, are applied to an entirety of the interior surfaces of enclosure <NUM>.

When electronic device <NUM> is in use, electronic device <NUM> will emit radiated emissions that may be reflected within the enclosure or escape through the walls of the enclosure, thereby causing interference and the like. The patterned structure <NUM> of each respective EMI sheet attenuator <NUM> can be designed to block specific frequencies of radiated emissions arriving at any angle and the frequency of the radiated emissions of an electronic device within the enclosure.

In one example implementation, electronic device <NUM> radiates emissions at <NUM>. When the EMI sheet attenuators were placed inside the enclosure, a <NUM> dB reduction was observed in the Total Radiated Power leaked from the enclosure and in Max E-Field measured outside the enclosure at <NUM> meters of distance.

Use of the EMI sheet attenuators is therefore shown to reduce electromagnetic field propagation within an enclosure, as compared to baseline electromagnetic field propagation within an enclosure that does not include EMI sheet attenuators. Thus, use of the EMI sheet attenuators 110A-F can provide a significant improvement from an enclosure that does not utilize EMI sheet attenuators 110A-F within an enclosure.

EMI sheet attenuators manufactured and implemented according to aspects of the disclosure provide significant flexibility for a designer to block and/or absorb radiated emissions of an electronic device within an enclosure. This flexibility may be beneficial when the electronic device within the disclosure is still being designed, and the radiated emissions are subject to change. Providing the ability for a user to attenuate radiated emissions by simply changing EMI sheet attenuators attached to a wall, as opposed to redesigning the enclosure, portions of the housing of the electronic device, components within the electronic device, printed circuit board, and the like may also be beneficial.

Design of the EMI sheet attenuator to attenuate an impedance of an electromagnetic field generated by an electronic device can depend on many factors, including the patterned structure, the number of layers, and the properties of the substrates. The dielectric properties of the substrate layers may be altered to impact the effectiveness of the patterned structure. For example, the thickness of the material forming the substrate layer, the dielectric constant of the material, tangent loss and the like can be modified to reduce the size of the printed shapes of the patterned structure on a given substrate layer or to make the same printed structure work at a different frequency. The spacing between the layers can also make a difference, which can be directly affected by the thickness of the adhesive layers used to attach the individual substrate layers together, which also affects how close together the substrate layers are positioned and how the electromagnetic wave propagates through EMI sheet attenuators. Thus, many factors can be taken into consideration when deigning EMI sheet attenuator <NUM>.

It is to be appreciated that EMI sheet attenuators manufactured according to aspects of the disclosure can be effective even when the impinging wave does not come at a <NUM> degree angle from the structure. EMI sheet attenuators are also equally effective to impinge waveforms in both near field, which is the field near the emitting electronic device or component, and far field, which is the field further away from the electronic device or component because their effectiveness depends on their impedance which can be adjusted on a case by case. This is in contrast to prior EMI shields and/or attenuators that may only be designed to be more effective in a certain field configuration. EMI sheet attenuators may also be broadband.

Implementation of the devices and methods disclosed herein can provide cost effective improvements across many applications. Such sheets can be used inside consumer electronic products (cell phones, laptops, google home) to increase isolation between antennas and to solve de-sense and coexistence problems. In the design or manufacture of servers, high-performance computing, and networks, individual EMI frequency sheets can be used to suppress radiated emissions without redesigning the enclosure or without the need to increase the overall shielding over the entire frequency range. Specific high frequencies may also be suppressed using the sheets disclosed herein for optical transceivers without a further increase in shielding performance due to the need for the design to include certain apertures (such as the main aperture needed for optical fibers to connect with their modules). Improvements can now be made to the coexistence and de-sense performance of devices at specific frequencies, such as WiFi, Bluetooth, and the like. Additionally, radiated emissions can be decreased when a non-metallic enclosure is used or when an imperfect shielding enclosure has to be used. Such EMI sheet attenuators may also be used in other applications, such as protective shielding within clothing, bags, and other accessories. In general, compliance with electromagnetic compatibility ("EMC") regulatory RE limits can be achieved from the methods and devices disclosed herein.

It is to be understood that the figures and descriptions of the present disclosure have been simplified to illustrate elements that are relevant for a clear understanding of the present disclosure, while eliminating, for purposes of clarity, many other elements which are conventional in this art. Those of ordinary skill in the art will recognize that other elements may be desirable for implementing the present disclosure.

It is noted that the terminology used above is for the purpose of reference only, and is not intended to be limiting. For example, terms such as "upper," "lower," "above," "below," "rightward," "leftward," "clockwise," and "counterclockwise" refer to directions in the drawings to which reference is made. As another example, terms such as "inward" and "outward" may refer to directions toward and away from, respectively, the geometric center of the component described. As a further example, terms such as "front," "rear," "side," "left side," "right side," "top," "bottom," "inner," "outer," "horizontal," and "vertical" describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology will include the words specifically mentioned above, derivatives thereof, and words of similar import.

Claim 1:
An electromagnetic interference ("EMI") sheet attenuator (<NUM>, <NUM>) comprising:
a planar conductive layer (<NUM>, <NUM>);
a first flexible substrate (<NUM>, <NUM>) including a top surface and an opposed bottom surface, the first flexible substrate overlying the planar conductive layer and including a conductive pattern (<NUM>, <NUM>) thereon, the conductive pattern being disposed at the top surface of the first flexible substrate; and
a second flexible substrate (<NUM>, <NUM>) including a top surface and an opposed bottom surface, the second flexible substrate overlying the first flexible substrate and including a further conductive pattern thereon, the further conductive pattern being disposed at the top surface of the second flexible substrate,
wherein the conductive pattern on the second flexible substrate is identical with the conductive pattern on the first flexible substrate and vertically aligned therewith thereby forming a stacked and three-dimensional structure.