DESC:RF RADIATION SHIELDING FABRIC WITH CAPACITIVE MATCHED LOAD

BACKGROUND
Technical field
The present invention generally relates to a RF radiation shielding fabric, and more particularly to RF radiation shielding fabric with a capacitive matched load (CML).

Description of the related art
People living or working near a cellular or mobile tower may be exposed to excessive radiations emitted from these towers, which may be coming through their windows & walls. The glass on the window is transparent to microwave radiations, so most of the radiations from these towers penetrate the home or office. A large number of scientists prepared Bio-Initiative Report in 2007 after going through nearly 2000 scientific papers and they proposed safe radiation density of 1.0 milliWatt/m2 for outdoor, cumulative RF exposure and 0.1 milliWatt/m2 for indoor, cumulative RF exposure. Again, 29 scientists from 10 countries prepared Bio-Initiative Report 2012 and gave additional references of 1800 scientific/technical papers. The most common complaints are: sleep disorder, headache, irritability, concentration problems, memory loss, depression, hearing loss, joint problems, etc. More severe reactions include seizures, paralysis, miscarriage, irreversible infertility, and cancer. In India, safe radiation density of 450 milliWatt/m2 has been adopted since Sep 01, 2012, which is extremely high from health point of view as people are exposed to this radiation 24x7.

Existing technologies and products are available to provide shielding solutions, such as metallic wire mesh, metallic sheets, transparent or semi- transparent special metalized films on the window, shielding textiles, etc. However, all these products reflect most of the radiations coming from towers outwards and only partial signal goes inside. The drawbacks of all these solutions are elaborated in the below paragraph.

In cases where the solutions like metallic wire mesh, metallic sheets, metalized films and textiles are installed, the reflected signal may travel to opposite buildings or other rooms or offices thereby affecting the other people and living beings. In addition, these solutions will reflect back the radiation present or generated within the room itself. The radiations in the room may be generated due to cell phones, tower located in the opposite direction, Wi-Fi, etc. The radiation coming through the walls or from other sides will experience internal reflections. Also, these metallic structures may themselves become resonant structure at some frequency; in that case, radiation from the edges will be significantly large. To solve this problem, some of the products use grounding but that is not very effective at cell phone and tower radiation frequencies.

Metallic sheets are in general, not acceptable by majority of the people as in addition to the above drawbacks, it blocks the view and there is no air flow through these sheets. Drawback of placing transparent or semi-transparent special metalized films on the windows is that one needs a trained manpower to install these films and also one has to close the windows to reduce the radiation coming inside, which will also prevent fresh air to come inside and stale air present inside the room to go outside the window. One can use metallic wire mesh on the windows, which will allow the movement of the air through the mesh but installation of the mesh is not always possible at all the windows, it suffers from internal reflection and the entire mesh itself may become a resonant configuration, which will have large radiation from the edges. Also, mesh size should be very small in order to reduce the radiation significantly, which reduces the visibility. Choices of colours are limited and may not match with the interior of the room.

The available shielding greatly suffers from internal reflection and the textile itself may become the resonant configuration, which will have large radiation from the edges. These textiles must have additional characteristics of graceful fall, proper stitching capability, easy to wash and dry, various colours to match the interior of the room/office, semi-transparent to opaque depending on the requirement, etc. Therefore, there is a need for a RF shield fabric which is capable of significantly blocking the RF radiations from entering the room and also should not affect other people. Further, the fabric should be available in various colours, size and pattern to match the interior of the room.

SUMMARY
In view of the foregoing, an embodiment herein provides a RF radiation shielding fabric with capacitive matched load (CML) for reducing RF radiations present in a room or a given area. The shielding fabric includes a stainless steel (SS) fiber material infused in cotton or a polyester fiber material to produce a metallic blend yarn. The yarn may be made of 15-20% by weight of SS fiber and 85-80% by weight of the cotton or the polyester fiber to produce the RF shielding fabric. At least one capacitive matched load (CML) which may be connected to the RF shielding fabric. The CML includes a small flexible Printed Circuit Board (PCB) or print on the shielding fabric. The PCB or the print on the shielding fabric includes a conductive metal ink or sheet for heat sink and a carbon ink or sheet for resistive load which may be capacitive coupled and stitched very closely to metallic portion of the yarn to obtain a shielding fabric with an electromagnetic interference (EMI) shielding properties.

In an embodiment, the CML facilitate incident radiation to be coupled to the resistive load and absorb radiation through capacitance between the CML and the metallic yarn portion of the shielding fabric. In another embodiment, the CML absorbs the radiation in frequency range between 750 MHz and 2.5 GHz.

In an example embodiment, the spacing between each of the stainless steel (SS) fiber material is in range 1.5mm to 3.5mm. In an embodiment, the CML is stitched near top and bottom sides of the shielding fabric with spacing in the range 6 cm to 12 cm between them in the horizontal direction to absorb the incident radiation on the shielding fabric. In an example embodiment, the shielding fabric may produce in various colours, texture, size and pattern. In another example embodiment, the shielding fabric may be easy to wash, dry and iron.

In an embodiment, the shielding fabric may be Semi-transparent to opaque in nature. In one embodiment, the shielding fabric may act as a reflective fabric when there is an incident radiation on the shielding fabric. In an embodiment, the conductive metal ink of the capacitive matched load (CML) may be a made of copper, silver, gold, aluminum or any conductive metal.

These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCIPTION OF THE DRAWINGS
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:

FIG. 1 illustrates an RF shielding fabric with a capacitive matched load (CML) stitched on top and bottom of the fabric according to an embodiment herein;
FIG. 2 illustrates an exploded view of the capacitive matched load (CML) according to an embodiment herein; and
FIG. 3 illustrates a metalized film with capacitive matched load (CML) is attached to a glass window according to an embodiment herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.

References in the specification to “one embodiment” or “an embodiment” member that a particular feature, structure, characteristics, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

As mentioned there remains a need for a RF shield fabric which is capable of significantly blocking the RF radiations from entering the room and also should not affect other people. Further, the fabric should be available in various colours, size and pattern to match the interior of the room. The present embodiment provides a RF shield fabric fulfilling the aforesaid need. Now referring to Fig. 1 to Fig. 3 for understanding various aspects of the embodiments better.

FIG. 1 illustrates an RF shielding fabric 12 with a capacitive matched load (CML) 16 stitched on top and bottom of the fabric 12 according to an embodiment herein. The shielding fabric 12 includes a stainless steel (SS) fiber 14 material which may be infused in cotton or polyester fiber material to produce a metallic blend yarn. In an embodiment, the yarn may be made of 15-20% by weight of SS fiber and 85-80% by weight of the cotton or the polyester fiber to produce the RF shielding fabric 12 and at least one capacitive matched load (CML) 16 which may be connected to the RF shielding fabric 12.

FIG. 2 illustrates an exploded view of the capacitive matched load (CML) 16 according to an embodiment herein. The CML 16 includes a small flexible Printed Circuit Board (PCB) or print 22 on the shielding fabric 12. The PCB or the print 22 on the shielding fabric 12 includes a conductive metal ink or sheet for heat sink 18 and a carbon ink or sheet for resistive load 20 which is capacitively coupled and stitched very closely to metallic portion of the yarn to obtain a shielding fabric 10 with an electromagnetic interference (EMI) shielding properties.

The CML 16 may facilitate incident radiation to be coupled to the resistive load 20 and absorb radiation through capacitance between the CML 16 and the metallic yarn portion of the shielding fabric 12. The CML 16 may absorb the radiation in frequency range between 750 MHz and 2.5 GHz. The spacing between each of the stainless steel (SS) fiber 14 material is in range 1.5mm to 3.5mm. The CML 16 may be stitched near top and bottom sides of the shielding fabric 12 with spacing in the range 6 cm to 12 cm between them in the horizontal direction to absorb the incident radiation on the shielding fabric 12.

In one embodiment, the shielding fabric 12 may be produced in various colours, texture, size and pattern, etc. but not limited to the embodiments mentioned herein. In another embodiment, the shielding fabric 12 may be easy to wash, dry and iron. In an embodiment, the shielding fabric 12 may be a semi-transparent to opaque in nature. In an example embodiment, the shielding fabric 12 may act as reflective when there is an incident radiation on the shielding fabric 12. In one embodiment, the conductive metal ink of the capacitive matched load (CML) 16 may be made of copper, silver, gold, aluminum or any conductive metal, etc. but not limited to the embodiments mentioned herein.

FIG. 3 illustrates a metalized film 26 with capacitive matched load (CML) 16 is attached to a glass window according to an embodiment herein. This is an additional embodiment where the shielding film may be used along with CML 16 to make the shielding on the glass window absorptive. The metalized film 26 may be attached to the glass and then one of the conductive metal ink 18 of the CML 16 may be affixed on the metalized film 26 and the other the conductive metal ink 18 of the CML may be affixed on an aluminum window frame 24. Thus, making the shielding on the glass window absorptive as well as reflective.

In one of the advantageous feature is converting the metalized reflective film into absorptive film using antenna concept by using CML 16. The value of the capacitance of the CML 16 may be optimized for the coupling between the film and the resistive load in the desired frequency range from 750 MHz to 3.5 GHz. In an embodiment, the value of the resistive load has been optimized for input impedance matching for maximum absorption. In another embodiment, the location of the CML 16 is optimized.
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. ,CLAIMS:What is claimed is:
1. An RF radiation shielding fabric (12) with a capacitive matched load (CML) (16), said shielding fabric comprising:
a stainless steel (SS) fiber/any other metal (14) material infused in cotton or polyester fiber material to produce a metallic blend yarn, wherein the yarn is made of 15-20%(may vary) by weight of metal fiber and 85-80% by weight of the cotton or the polyester fiber to produce the RF shielding fabric (12); and
at least one capacitive matched load (CML) (16) connected to the RF shielding fabric (12), wherein the CML (16) comprises a small flexible Printed Circuit Board (PCB) or print (22) on the shielding fabric (12), wherein the PCB or the print (22) on the shielding fabric (12) comprises a conductive metal ink or sheet for heat sink (18) and a carbon ink or sheet for resistive load (20) which is capacitive coupled and stitched very closely to metallic portion of the yarn to obtain a shielding fabric (10) with an electromagnetic interference (EMI) shielding properties.

2. The RF radiation shielding fabric of claim 1, wherein the CML (16) facilitate incident radiation to be coupled to the resistive load (20) and absorb radiation through capacitance between the CML (16) and the metallic yarn portion of the shielding fabric (12).

3. The RF radiation shielding fabric of claim 1, wherein the CML (16) absorbs the radiation in frequency range between 750 MHz and 2.5 GHz.

4. The RF radiation shielding fabric of claim 1, wherein the spacing between each of the stainless steel (SS)/metal fiber (14) material is in range 1.5mm to 3.5mm but may vary depending on radiation intensity.

5. The RF radiation shielding fabric of claim 1, wherein the CML (16) is stitched near top and bottom sides of the shielding fabric (12) with a spacing in the range 6 cm to 12 cm but may vary depending on radiation intensity between them in the horizontal direction to absorb the incident radiation on the shielding fabric (12).

6. The RF radiation shielding fabric of claim 1, wherein the shielding fabric (12) is produced in various colors, texture, size and pattern.

7. The RF radiation shielding fabric of claim 1, wherein the shielding fabric (12) is easy to wash, dry and iron.

8. The RF radiation shielding fabric of claim 1, wherein the shielding fabric (12) is semi-transparent to opaque in nature.

9. The RF radiation shielding fabric of claim 1, wherein the shielding fabric (12) acts as absorptive and reflective when there is an incident radiation on the shielding fabric (12).

10. The RF radiation shielding fabric of claim 1, wherein the conductive metal ink of the capacitive matched load (CML) (16) is a made of copper, silver, gold, aluminum or any conductive metal.

Dated 19th April 2016

VINEED NAIR
IN/PA – 2198
[ATTORNEY FOR THE APPLICANT]