High-gain metamaterial slot antenna

Abstract

This subject provides an RFID device configured to improve the gain and directivity of an antenna. [Solution] The RFID device comprises an antenna, a metamaterial (MTM) array, and a substrate. The substrate has a first surface and a second surface, and the antenna has a bottom surface and an top surface. The bottom surface of the antenna and the MTM array are formed on the first surface of the substrate. The antenna and the MTM array are separated by a gap. The antenna is formed of a first conductive material defining a region enclosed by a first boundary line. The antenna has nested slots. The MTM array is formed of a second conductive material defining a region enclosed by a second boundary line.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 482,125, filed on January 30, 2024, which is hereby incorporated by reference in its entirety.

[0002] Antenna design, particularly RFID antenna design and RFID devices including antennas and metamaterial (MTM) arrays that improve the gain and directivity of antennas.

Background Art

[0003] Radio Frequency Identification (RFID) technology has been growing rapidly in a wide range of applications such as item tracking, supply chain processes, highway toll collection systems, parking lots, and gas stations. Generally, an RFID system consists of an RFID tag with an integrated circuit (IC) chip, an antenna, and an RFID reader. The basic operation involves data transfer and communication between the RFID reader and the RFID tag. In the context of a highway toll collection system, the RFID tag is usually attached to the front windshield of a vehicle, and the RFID reader is installed at the toll gate. The effectiveness of communication depends on factors such as the type of tag (i.e., passive or active), the reading range of the RFID tag, the installation angle and height of the RFID reader, the RFID frequency, and interference from the surrounding environment or other RFID tags and readers.

Summary of the Invention

Problems to be Solved by the Invention

[0004] At toll booths, existing RFID systems face various challenges, including poor RFID tag detection performance, interference from metal films attached to vehicle windshields, and increased waiting times for vehicles in queues. For example, long waiting times at highway toll booths are due to the need to identify and classify vehicles even while they are moving. The toll collection process requires real-time vehicle recognition and classification, and if RFID tags are not properly detected, it can lead to queue delays. The problem of poor RFID tag detection performance is usually attributed to the setting of the RFID reader's antenna angle, particularly when the RFID reader's antenna is set at an angle between 30 and 90 degrees. For example, if the RFID reader is installed facing vehicles entering the side of a toll booth, this angle setting may be based on a reference point. In this context, setting the RFID reader to 90 degrees means that the RFID reader's antenna is positioned 90 degrees away from the reference point. Detecting conventional RFID tags can be difficult at certain antenna angles, particularly when positioned within the 30 to 90 degree range. This specific antenna configuration may not be well aligned with the preferred orientation necessary for reliable RFID communication with conventional tags, creating complexity in achieving efficient tag detection. Conventional RFID tags may not perform at their best at certain angles (i.e., 30 to 90 degrees) and may not perform to their full potential at other angles. Furthermore, significant performance issues arise with RFID tags attached to windshields with metal films. Metal films contain very small metal particles that are invisible to the naked eye but reflect some light (ultraviolet rays, etc.) and heat. However, these films can interfere with radio frequency signals.

[0005] It is necessary to overcome the aforementioned limitations and drawbacks associated with conventional wireless communication devices, i.e., RFID devices. Furthermore, there is a need for a simplified RFID device structure that provides high gain and directivity to the RFID device antenna. [Means for solving the problem]

[0006] The following is a general summary to provide a basic understanding of some aspects of the disclosed technological innovations. This summary is not a comprehensive overview and is not intended to identify or limit or clearly define the scope of any major / key elements. Its sole purpose is to present some concepts in a general form as an introduction to the content that will be detailed later.

[0007] This section describes RFID devices with improved or enhanced antenna gain and directivity. In some embodiments, the RFID device comprises an antenna, a metamaterial (MTM) array, and a substrate. The substrate is made of a flexible material and has a first surface and a second surface. The antenna further comprises a bottom surface and a top surface. Furthermore, the bottom surface of the antenna and the MTM array are formed on the first surface of the substrate. The antenna and the MTM array are separated by spacing. The antenna is formed of a first conductive material that defines a region enclosed by a first boundary line. The antenna may also include nested slots. In some embodiments, a chip is located on the top surface of the antenna and is electrically coupled to the antenna.

[0008] In some embodiments, the MTM array is formed of a second conductive material surrounded by a second boundary. The long side of the second boundary of the MTM array is arranged parallel to the long side of the first boundary of the antenna. The antenna and the MTM array are coplanar with each other, and the antenna is inductively coupled to the MTM array. Furthermore, the MTM array has an MxN array configuration. The MxN MTM array configuration consists of "M" MTM rows and "N" MTM columns.

[0009] Each of the multiple MTM cells is positioned at a predetermined distance from one or more corresponding adjacent MTM cells. Furthermore, the antenna response is a function based on the antenna's impedance characteristics, the MTM arrangement, and the negative permeability of the MTMs.

[0010] In some embodiments, the RFID device includes one or more vulnerable areas. Each of these vulnerable areas is defined at a predetermined distance from the chip. The one or more vulnerable areas are configured to be destroyed if an attempt is made to remove the attached RFID device. The one or more vulnerable areas extend over at least a portion of the antenna and MTM array, and if the RFID device is damaged along one or more vulnerable areas, it will lose the ability to communicate with the RFID reader. In some embodiments, an adhesive coating is applied to a second surface of the substrate, allowing the RFID device to be attached to the glass material of a vehicle. In some embodiments, the RFID device is configured to be readable by an RFID reader when positioned at a specific angle within a range of 30 to 90 degrees from a reference point, making it possible to more effectively retrieve information from the attached RFID device. [Brief explanation of the drawing]

[0011] The above summary and the following detailed description of exemplary embodiments will be better understood when read in conjunction with the drawings. Exemplary structures of the subject matter are shown in the drawings to illustrate it. However, the subject matter is not limited to the specific methods and means disclosed herein. Those skilled in the art will also understand that these drawings are not to scale. Wherever possible, similar elements are indicated by the same number.

[0012] [Figure 1] This shows a schematic diagram of an RFID device according to one embodiment.

[0013] [Figure 2A-2B] A schematic diagram of an MTM sequence according to one embodiment is shown.

[0014] [Figure 3A-3B] This shows a plan view of an RFID device according to one embodiment.

[0015] [Figure 4A-4B] This shows an exemplary simulation result of an RFID device according to one embodiment.

[0016] [Figure 5] The graph shows an exemplary result of the reading range of an RFID device according to one embodiment.

[0017] [Figure 6] The graph shows exemplary gain results for an RFID device according to one embodiment.

[0018] In the attached diagram, underlined numbers are used to represent the object where the number is located or adjacent objects. Ununderlined numbers refer to objects connected to the number by a line. Additionally, when an ununderlined number is shown with an arrow, it is used to indicate the general object that the arrow is pointing to. [Modes for carrying out the invention]

[0019] Before further detailing this subject matter, please understand that it is not limited to the specific embodiments described and is naturally subject to change. Furthermore, since the scope of this subject matter is limited only by the attached claims, please understand that the terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in the field to which this disclosure applies. Furthermore, it should be noted that the singular forms “a,” “an,” and “the” used herein and in the appended claims include the plural unless the context clearly indicates otherwise.

[0021] In the following detailed description, various embodiments of the present subject matter and methods of implementing the same are shown. Although the examples of methods and materials described are limited for the sake of clarity, those skilled in the art in the relevant technical field will understand that other methods and materials are possible for implementing or applying the present subject matter. I. Definitions

[0022] As used herein, "RFID" refers to a radio frequency identification device.

[0023] As used herein, "RFID device" refers to a device including an antenna and an MTM array.

[0024] As used herein, "RFID reader" refers to a device having one or more antennas that transmit radio waves and receive signals returned from an RFID device.

[0025] As used herein, "RFID tag" refers to a label including an RFID device that may be attached to the front glass of a vehicle to identify the vehicle at toll booths, parking lots, garages, fueling stations, etc.

[0026] As used herein, "substrate" shall refer to a dielectric material. A dielectric material is a non-metallic substance having a high specific resistance.

[0027] [[ID=**26]] As used herein, "negative magnetic permeability" shall refer to the negative magnetic permeability when a material forms magnetic dipoles in the opposite direction of an applied magnetic field in response to the applied magnetic field.

[0028] As used herein, "gain" shall indicate how well the input power is converted into radio waves in a specific direction at a transmitting antenna. At a receiving antenna, the gain shall indicate how well radio waves arriving from a specific direction are converted into power.

[0029] Note: There seems to be a formatting issue with the line numbering in the original text where line ID 26 has an incorrect indentation. This has been maintained in the translation. If this is a mistake in the original, it may need to be corrected for proper readability.The term "reading range" used here refers to the maximum distance at which an RFID device can detect radio waves from an RFID reader. When an RFID device is within this range, it becomes active, and the RFID reader can acquire information from it.

[0030] The term "directivity" used here refers to the ability of an antenna to concentrate radiation in a specific direction.

[0031] "Metamaterials" (MTMs) refer to materials designed to possess properties not found in naturally occurring materials. They consist of a collection of multiple elements made from composite materials such as metals and plastics. These materials are typically arranged in repeating patterns on a scale smaller than the wavelength of the phenomena they affect. The properties of MTMs derive from their newly designed structure, not from the properties of the substrate. Their precise shape, geometric structure, size, orientation, and arrangement give MTMs smart properties that allow them to manipulate electromagnetic waves, such as blocking, absorbing, amplifying, or bending waves, resulting in superior effects compared to conventional materials.

[0032] The term "boundary line" used herein refers to the boundary line of a conductive material.

[0033] As used herein, "antenna" refers to a conductor configured to transmit and receive electromagnetic radiation.

[0034] In the context of RFID readers, the term “reference point” refers to the starting or zero position used as a reference when measuring the angle of the RFID reader relative to the direction of the approaching vehicle and road.

[0035] These and other features, aspects, embodiments and advantages of the subject matter will be better understood by referring to the description below and the attached claims. These definitions are for the purpose of providing a concise introduction to the selection of concepts. These definitions are not intended to identify the primary or essential features of the claimed or disclosed subject matter, nor are they intended to be used to limit the scope of the claimed subject matter. II. Improving the gain and directivity of RFID device antennas

[0036] The RFID devices disclosed herein are described in detail with reference to examples and drawings. Unless otherwise specified, similar numbers in the drawings refer to the same, similar, or corresponding elements throughout the drawings. The examples, arrangements, configurations, parts, elements, apparatus, methods, materials, etc. disclosed and described herein may be modified, and may be desired, for specific applications.

[0037] In this disclosure, any specific shapes, materials, techniques, arrangements, etc., are either related to the specific examples presented or are general descriptions. No specific details or examples are intended, and should not be construed, as essential or restrictive unless specifically stated otherwise.

[0038] In some embodiments, the subject matter relates to an RFID device including an antenna and an MTM array. The antenna and MTM array are designed, constructed, and configured so that the RFID device can utilize the antenna and MTM array together to improve the antenna's gain and directivity when exposed to incident radio waves from an RFID reader.

[0039] In this specification, an RFID device refers to a wireless identification device installed on a vehicle, particularly on the windshield, that enables vehicle identification when queryed by an RFID reader. The RFID device transmits vehicle identification information (e.g., one or more identifiers) in response to a query from an RFID reader, enabling a service provider to identify an amount and withdraw the amount from an electronic wallet linked to the vehicle. Here, "nested slots" refers to an antenna with multiple slots.

[0040] Figure 1 shows a schematic diagram of an RFID device 100 according to one embodiment. Here, we describe an RFID device 100 for an RFID tag that has both high gain and a wide reading range. The RFID tag includes the RFID device 100, an adhesive (not shown in Figure 1), and a release liner (not shown in Figure 1). The RFID tag can be attached to a vehicle (not shown in Figure 1), particularly the windshield (not shown in Figure 1), by peeling off the release liner.

[0041] The RFID device 100 includes a substrate 101, an antenna 102, and an MTM array 105. The substrate 101 is made of a flexible material having a first surface 101a and a second surface 101b. The antenna 102 and the MTM array 105 are formed on the first surface 101a of the substrate 101. The antenna 102 is made of a first conductive material that defines a region enclosed by a rectangular first boundary line 109. The first conductive material includes a metal (e.g., aluminum or copper) or other conductive materials known in the art (e.g., conductive ink). The antenna 102 having multiple slots, i.e., nested slots 108, may be designed in a specific shape and dimensions to achieve desired electrical performance. The specific shapes and dimensions of the slots 108 are created by performing cutting operations on the first conductive material at various locations to form the antenna 102 as shown in Figure 1. Furthermore, cutting may be achieved by mechanical die-cutting, etching, laser cutting, or other suitable methods for cutting and removing unwanted material such as nested slots 108. Also, if the antenna 102 is formed by printing conductive ink, the slots 108 may be formed by a pattern of printing ink, in which case cutting is not necessary. Nested slots 108 refer to openings or holes that represent non-conductive portions of the antenna 102. For example, if the antenna 102 having nested slots 108 is placed on a non-conductive or dielectric material such as a substrate 101, the nested slots 108 function as non-conductive portions.

[0042] The MTM array 105 is formed by a second conductive material that defines a region enclosed by a second rectangular boundary line 110. The second conductive material may be the same as or different from the first conductive material used for the antenna 102. The MTM array 105 in Figure 1 is formed in an MxN array configuration. The MxN MTM array 105 has multiple MTM cells 107. The multiple MTM cells 107 are designed with specific dimensions and geometric configurations, and care is taken to ensure impedance matching with the antenna 102. The matching between the MTM array 105 and the antenna 102 is important because it allows different components (i.e., the MTM array 105 and the antenna 102) to work together to achieve desired results (e.g., maximum efficiency) and avoid potential problems arising from mismatched or incompatible components. In an MxN MTM array configuration, "M" indicates the number of rows and "N" indicates the number of columns. The MxN MTM array 105 has multiple MTM cells 107. For example, the multiple MTM cells 107 shown in Figure 1 are arranged in a 2x43 MTM array configuration. Based on specific dimensions and geometric configurations, the multiple MTM cells 107 are formed on a second conductive material that defines a region enclosed by a second boundary line 110, for example by a cutting operation.

[0043] The cutting operation selectively removes unwanted portions from the configuration of the MTM array 105 to achieve the desired shape and dimensions. Furthermore, the cutting may be achieved by mechanical die-cutting, etching, laser cutting, or other suitable method for cutting and removing unwanted material. This removal of unwanted material creates openings or holes representing non-conductive portions of the MTM array 105. For example, the non-conductive portions may be air, insulating material, or dielectric material such as the substrate 101. The specific geometric shape of the MTM cell 107 includes the shape of multiple MTM cells 107. Examples of shapes for multiple MTM cells 107 include squares, rectangles, circles, triangles, or combinations thereof. The specific dimensions of the MTM cell 107 include, but are not limited to, width and distance. For example, the width of multiple MTM cells 107 may include the width of the internal conductor and the width of the external conductor, and the dimensions of multiple MTM cells 107 may include the distance between the internal and external conductors, and the distance between each of the multiple MTM cells 107 and one or more corresponding adjacent MTM cells 107. Alternatively, if the MTM cell 107 is formed by printing conductive ink, openings or holes can be formed by the printed ink pattern, in which case cutting is not necessary. The antenna 102 includes an upper surface 102a and a lower surface 102b. The upper surface 102a of the antenna 102 is on the opposite side of the lower surface 102b. The lower surface 102b of the antenna 102 and the MTM array 105 are positioned on the first surface 101a of the substrate 101, and the antenna 102 and the MTM array 105 are separated by a gap 106. The long side 112 of the second boundary line 110 of the MTM array 105 is positioned parallel to the long side 111 of the first boundary line 109 of the antenna 102. The MTM array 105 and the antenna 102 are positioned on the same plane.

[0044] The substrate 101 is a dielectric material. The substrate 101 is any dielectric material known in the art and is selected depending on the specific antenna and / or application. The substrate is, for example, a paper substrate or a polyethylene terephthalate (PET) substrate, but is not limited to these. The top surface 102a of the antenna 102 includes one or more feed point marks 103 and a chip 104. For example, one or more feed point marks 103 are used to define the chip placement area. The chip 104 is electrically coupled to the antenna 102. For example, electrical coupling is achieved by directly attaching the chip 104 to the antenna 102, or by using a strap or other electrical coupling techniques known in the art to attach the chip 104 to the antenna 102. The antenna 102 is inductively coupled to the MTM array 105. For example, in inductive coupling, the antenna 102 and the MTM array 105 are coupled via a magnetic field. The antenna 102 is configured to receive incident electromagnetic signals transmitted from an RFID reader (not shown in Figure 1). The incident electromagnetic wave transmitted from the RFID reader induces RF power in the antenna 102. The antenna 102 is further configured to induce RF power in the MTM array 105 by inductive coupling. In another embodiment, the antenna 102 is configured to induce RF power in the MTM array 105 by capacitive coupling.

[0045] As an example, the RFID device 100 may be installed on the windshield of a vehicle. The RFID device 100 includes a substrate 101, an antenna 102, and an MTM array 105. The substrate 101 has a first surface 101a and a second surface 101b. The antenna 102 and the MTM array 105 are formed on the first surface 101a of the substrate 101. The second surface 101b of the substrate 101 is on the opposite side of the first surface 101a. Furthermore, the second surface 101b of the substrate 101 is coated with an adhesive coating and a release liner. To attach the RFID device 100 to the windshield of a vehicle, the release liner is removed and the RFID device 100 is fixed to the windshield using the adhesive coating. The adhesive coating adheres the substrate 101 to the windshield. The RFID reader can be installed at toll booths, parking lots, gas stations, etc. The RFID device 100 on the vehicle communicates with an RFID reader and provides vehicle identification information (e.g., one or more identifiers) that enables the service provider to identify the amount and withdraw it from the electronic wallet associated with the vehicle. The RFID device 100 is configured to be read by the RFID reader when positioned at a specific angle, including a range of 30 to 90 degrees, to facilitate reliable information retrieval from the mounted RFID device 100. For example, an RFID reader at a 60-degree angle means that the RFID reader is positioned 60 degrees away from a reference point.

[0046] Figures 2A and 2B show schematic diagrams of a metamaterial (MTM) array 200 according to one embodiment. The MTM array 200 according to this embodiment includes a plurality of MTM cells 201 arranged on a substrate 101 (as shown in Figure 1). Each MTM cell 201 includes an internal conductor 204 and an external conductor 203. The external conductor 203 and internal conductor 204 are formed on the first surface 101a of the substrate 101 (as shown in Figure 1). The internal conductor 204 is positioned opposite the external conductor 203 and is located inside the external conductor 203. Each of the external conductor 203 and internal conductor 204 has a square shape with separated portions and is arranged with a predetermined distance g1 between them. In addition, each of the plurality of MTM cells 201 is arranged at a predetermined distance g2 from one or more corresponding adjacent MTM cells 201. In one example of the configuration of the MTM array 200, the default width W of the inner conductor 204 is 0.2 mm, the default width W of the outer conductor 203 is 0.2 mm, the distance g1 between the inner conductor 204 and the outer conductor 203 is 0.3 mm, and the distance g2 between each MTM cell 201 and one or more adjacent MTM cells 201 is 0.4 mm. Each of the multiple MTM cells 201 contains square-shaped conductors with spaced portions, such as the inner conductor 204 and the outer conductor 203.

[0047] (As shown in Figure 1) Antenna 102 is configured to receive electromagnetic waves from an RFID reader (not shown in Figure 1). Returning to Figure 1, Antenna 102 is excited in response to the RF power induced by the incident electromagnetic waves. Furthermore, Antenna 102 is configured to induce RF power in the MTM array 105 via inductive coupling. The MTM array 105 responds to the induced RF power, and as a result of both Antenna 102 and the MTM array 105 being excited, current is distributed in both Antenna 102 and the MTM array 105. This current distribution results in a high overall current distribution within the RFID device 100. As a result, the RFID device 100 exhibits high radiation efficiency due to the high current distribution. This high current distribution is achieved by achieving impedance matching between the RFID reader and the RFID device 100 in the RFID device 100, including Antenna 102, Chip 104, and MTM array 105. The impedance matching achieved in the RFID device 100 is based on, but is not limited to, one or more factors, including the antenna design or impedance network of antenna 102, the shape and dimensions of the MTM cells 107, the impedance characteristics of antenna 102 and the MTM array 105, and the negative permeability of the MTM. The impedance characteristics of antenna 102 and the MTM array 105 may include components related to resistance, capacitance, and inductance. Multiple MTM cells 107 include specific geometric shapes, such as a square ring with separated portions, which, when excited by RF power, function as an LC (L: inductor, C: capacitor) resonant circuit and exhibit negative permeability at the resonant frequency. The resonant frequency may be any frequency within the operating frequency range of the RFID device, for example, the U.S. Federal Communications Commission (FCC) ultra-high frequency (UHF) RFID bands, i.e., the ranges of 865 MHz to 868 MHz and 902 MHz to 928 MHz. However, the frequency values ​​of 865MHz-868MHz and 902MHz-928MHz are examples only, and should not be considered as limitations, as the permitted frequency bands for use vary by region and country.Those skilled in the art will recognize that using the MTM array 105 in the configuration of the antenna 102 improves the overall parameters of the RFID device 100, such as radiation efficiency, gain, and directivity. The MTM array 105, having negative permeability, improves the characteristics of the antenna 102, such as directivity, gain, and radiation efficiency. Furthermore, the disclosed antenna 102 design with the MTM array 105 enables complex impedance matching even when the RFID device 100 is mounted on high dielectric constant materials such as tempered glass, which is commonly found in vehicle windshields.

[0048] Figures 3A and 3B show plan views of an RFID device 300 according to one embodiment. In relation to Figure 3A, the RFID device 300 includes one or more vulnerable regions 3a and 3b. For example, to attach the RFID device 300 to the windshield of a vehicle, the user removes the release liner (not shown in Figures 3A and 3B) of the RFID device 300. Once the release liner is removed, the adhesive coating layer (not shown in Figures 3A and 3B) of the RFID device 300 adheres the substrate 101 (see Figure 1) to the windshield. One or more vulnerable regions 3a and 3b may contain a fragile conductive material, a special adhesive compound, etc. Also, in relation to Figure 1, the special adhesive compound may be applied to the second surface 101b of the substrate 101. Each of the one or more vulnerable regions 3a and 3b is defined at a predetermined distance from the chip 303 and is configured to break when an attempt is made to remove the attached RFID device 300. One or more vulnerable regions 3a and 3b extend across at least a portion of the antenna 301 and the MTM array 302, and if the RFID device 300 is damaged along one or more vulnerable regions 3a and 3b, the RFID device 300 will lose the ability to communicate with the RFID reader. Figure 3B shows the damaged or altered regions 4a and 4b of the RFID device 300.

[0049] Figures 4A and 4B show exemplary simulation results of the RFID device 100 shown in Figure 1, according to one embodiment. Figure 4A shows the electric field strength of antenna 102 without the MTM array 105. The electric field strength of antenna 102 without the MTM array 105 is, for example, about 7 V / m (volts / meter). Figure 4B shows the electric field strength of antenna 102 with the MTM array 105. The electric field strength of antenna 102 with the MTM array 105 is, for example, about 9 V / m. The electric field strength of the RFID device 100 improves by about 2 V / m when using the MTM array 105 compared to when using antenna 102 alone. Thus, using the MTM array 105 together with antenna 102 improves the gain and directivity of antenna 102.

[0050] Figure 5 shows a graph illustrating the exemplary reading range results of the RFID device 100 shown in Figure 1, according to one embodiment. The electric field strength distribution of antenna 102 and RFID device 100 is shown in Figures 4A and 4B. The reading range of the RFID device 100 corresponding to the electric field strength distribution is shown in Figure 5. When operating in the FCC UHF band, the reading range is improved by 2 meters. The dashed line shows the reading range of antenna 102 without the MTM array 105. The solid line shows the reading range of antenna 102 with the MTM array 105. The reading range of antenna 102 with the MTM array 105 is improved by 2 meters compared to antenna 102 without the MTM array 105.

[0051] Figure 6 shows a graph illustrating an example of the gain results of the RFID device 100 shown in Figure 1, according to one embodiment. Figure 6 shows the gain of the RFID device 100, including the antenna 102 and the MTM array 105.

[0052] However, it will be apparent to those skilled in the art relating to the subject matter that many modifications are possible without departing from the concept of the invention, beyond those already described. Therefore, the subject matter of the invention is not limited except to the spirit of this disclosure. Furthermore, in interpreting this disclosure, all terms should be interpreted in the broadest sense that is consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring non-exclusively to an element, part, or process, indicating that the referenced element, part, or process may exist, be used, or be combined with other elements, parts, or processes that are not expressly referenced.

Claims

1. An antenna having a bottom surface and a top surface, Metamaterial (MTM) arrays and The device comprises a substrate made of a flexible material having a first surface and a second surface, The lower surface of the antenna and the MTM array are formed on the first surface of the substrate. The antenna and the MTM array are separated by a distance. RFID device.

2. The device according to claim 1, wherein the antenna is formed of a first conductive material that defines a region enclosed by a first boundary line.

3. The device according to claim 1, wherein the antenna comprises nested slots.

4. The device according to claim 1, wherein the MTM array is formed by a second conductive material defining a region enclosed by a second boundary line.

5. The device according to claim 1, wherein the longer side of the second boundary line of the MTM array is arranged parallel to the longer side of the first boundary line of the antenna.

6. The device according to claim 5, wherein the antenna and the MTM array are on the same plane.

7. The device according to claim 1, wherein the chip is disposed on the upper surface of the antenna.

8. The device according to claim 7, wherein the chip is electrically connected to the antenna.

9. The device according to claim 1, wherein the antenna is inductively coupled to the MTM array.

10. The device according to claim 1, wherein the MTM array comprises an M x N array configuration.

11. The device according to claim 10, wherein the M x N MTM array configuration comprises "M" MTM rows and "N" MTM columns.

12. The device according to claim 11, wherein the M x N MTM array configuration comprises a plurality of MTM cells arranged in 2 rows and 43 columns.

13. The device according to claim 12, wherein each of the plurality of MTM cells is spaced a predetermined distance from one or more corresponding adjacent MTM cells.

14. The device according to claim 11, wherein the shapes of the plurality of MTM cells are selected from the group consisting of squares, rectangles, circles and triangles.

15. The RFID device according to claim 1, wherein the response of the RFID device is a function of the impedance characteristics of the antenna and the MTM array and the negative permeability of the MTM.

16. The device according to claim 1, wherein an adhesive coating is applied to the second surface of the substrate.

17. The RFID device further comprises one or more vulnerable regions according to claim 1.

18. The device according to claim 17, wherein each of the one or more vulnerable regions is defined at a predetermined distance from the chip, and the one or more vulnerable regions are configured to be damaged when an attempt is made to remove the attached RFID device.

19. The device according to claim 18, wherein the one or more vulnerable regions extend over at least a portion of the antenna and the MTM array, and the RFID device becomes unable to communicate with an RFID reader if it is damaged along the one or more vulnerable regions of the RFID device.

20. The RFID device is configured to be read by the RFID reader when positioned at a specific angle including a range of 30 to 90 degrees from a reference point, and the device according to claim 1 facilitates reliable functionality for obtaining information from the mounted RFID device.

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