High-gain metamaterial loaded slot antenna

Abstract

The present subject matter provides an RFID device configured to provide improved antenna gain and directivity. The RFID device includes an antenna, a metamaterial (MTM) array, and a substrate. The substrate includes a first surface and a second surface, and the antenna includes a bottom surface and a 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 from a first conductive material defining an area surrounded by a first perimeter. The antenna includes a nesting slot. The MTM array is formed from a second conductive material defining an area surrounded by a second perimeter.

Description

[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 incorporated herein by reference in its entirety. Technical Field

[0002] Antenna design (particularly RFID antenna design and RFID devices) includes antennas and metamaterial (MTM) arrays that enhance antenna gain and directivity. Background Art

[0003] Radio frequency identification (RFID) technology is rapidly growing in a wide range of applications, including object tracking, supply chain processes, highway toll collection systems, automated parking, and gas stations. Typically, an RFID system consists of an RFID tag containing an integrated circuit (IC) chip, an antenna, and an RFID reader. Basic operation involves data transmission / communication between the RFID reader and the RFID tag. In the context of highway toll collection systems, the RFID tag is typically mounted on the vehicle's windshield, while the RFID reader is installed at the toll booth. The effectiveness of communication depends on factors such as the tag type (i.e., passive or active), the RFID tag's read range, the RFID reader's mounting angle and height, the RFID frequency, and interference from the surrounding environment or from other RFID tags and readers.

[0004] Existing RFID systems at toll plazas face various challenges, including poor RFID tag detection, interference caused by metal films mounted on vehicle windshields, and increased wait times for vehicles in queues. For example, the need to identify and classify vehicles, even when they are moving, can lead to longer wait times at highway toll booths. The toll collection process requires real-time vehicle identification and classification, so incorrectly detecting RFID tags can cause delays in queues. Poor RFID tag detection is often attributed to the RFID reader antenna angle, particularly when the RFID reader antenna is set at an angle between 30 and 90 degrees. For example, if the RFID reader is mounted on the side of the toll booth facing incoming vehicles, the angle can be set relative to a reference point. In this context, a 90-degree angle setting of the RFID reader means that the RFID reader antenna is positioned at 90 degrees to the reference point. Detecting conventional RFID tags can be challenging when the RFID reader antenna is positioned at certain angles, particularly within the 30-90 degree range. This specific reader antenna configuration introduces complications in achieving effective tag detection for conventional tags, as it may not be effectively aligned with the preferred orientation required for reliable RFID communication with the tag. Conventional RFID tags do not achieve maximum performance at limited angles (i.e., 30 to 90 degrees), resulting in inferior performance compared to other possible angles. Furthermore, windshields with metallized films pose significant performance challenges for RFID tags applied to such windshields. Metallized films contain very small metal particles, invisible to the naked eye, that reflect light (such as UV rays) and heat to a certain extent. However, they can interfere with radio frequency signals.

[0005] There is a need to overcome the aforementioned limitations and disadvantages associated with conventional wireless communication devices (ie, RFID devices). Additionally, there is a need for a simplified RFID device structure that achieves high gain and directivity for the RFID device's antenna. Summary of the Invention

[0006] The following presents a general overview in order to provide a basic understanding of some aspects of the disclosed innovation. This summary is not an extensive overview and is not intended to identify or limit key / critical elements or outline its scope. Its sole purpose is to present some concepts in a general form as a prelude to the more detailed description presented later.

[0007] This document describes an RFID device with increased or improved antenna gain and directionality. In some embodiments, the RFID device includes an antenna, a metamaterial (MTM) array, and a substrate. The substrate is a flexible material having a first surface and a second surface. The antenna also includes 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 a gap. The antenna is formed from a first conductive material that defines an area surrounded by a first perimeter. Furthermore, the antenna may include a nesting slot. In some embodiments, a chip is disposed on the top surface of the antenna. The chip is electrically coupled to the antenna.

[0008] In some embodiments, the MTM array is formed of a second conductive material surrounded by a second perimeter. The elongated edge of the second perimeter of the MTM array is arranged parallel to the elongated edge of the first perimeter of the antenna. The antenna and the MTM array are coplanar, and the antenna is inductively coupled to the MTM array. Furthermore, the MTM array includes an MxN array configuration. The MxN MTM array configuration includes M MTM rows and N MTM columns.

[0009] Each of the plurality of MTM cells is spaced apart from corresponding one or more adjacent MTM cells by a predetermined distance.In addition, the response of the antenna is a function of the impedance characteristics of the antenna and the MTM array and the negative permeability of the MTM.

[0010] In some embodiments, the RFID device includes one or more fragile regions. Each of the one or more fragile regions is defined at a predetermined distance from the chip. The one or more fragile regions are configured to break when an attempt is made to remove the attached RFID device. The one or more fragile regions extend across at least a portion of the antenna and the MTM array, such that when the RFID device breaks along the one or more fragile regions of the RFID device, it is rendered unable to communicate with the RFID reader. In some embodiments, the substrate has an adhesive coating applied to its second surface to enable the RFID device to be attached to a glass material associated with the vehicle. In some embodiments, the RFID device is configured to be read by an RFID reader when positioned at a specific angle (including a range of 30 degrees to 90 degrees from a reference point), thereby facilitating more efficient information retrieval from the attached RFID device. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above summary and the following detailed description of the illustrative embodiments may be better understood when read in conjunction with the accompanying drawings. To illustrate the present subject matter, exemplary configurations of the subject matter are shown in the accompanying drawings. However, the present subject matter is not limited to the specific methods and means disclosed herein. Furthermore, those skilled in the art will appreciate that the drawings are not drawn to scale. Where possible, identical elements are indicated by identical numerals.

[0012] Figure 1 A schematic diagram illustrating an RFID device according to one embodiment; Figure 2A and Figure 2B A schematic diagram illustrating an MTM array according to one embodiment; Figure 3A and Figure 3B shows a plan view of an RFID device according to one embodiment; Figure 4A and Figure 4B shows example simulation results of an RFID device according to one embodiment; Figure 5 shows a graph showing example read range results for an RFID device according to one embodiment; and Figure 6 A graph showing example gain results for an RFID device according to one embodiment is shown.

[0013] In the accompanying drawings, underlined numbers are used to indicate the item in which the underlined number appears or the item to which the underlined number is adjacent. Non-underlined numbers are associated with the item identified by a line linking the non-underlined number to the item. When a number is non-underlined and has an associated arrow, the non-underlined number is used to identify the general item to which the arrow points. DETAILED DESCRIPTION

[0014] Before describing the present subject matter in further detail, it should be understood that the present subject matter is not limited to the particular embodiments described, as such embodiments may, of course, vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, as the scope of the present subject matter will be limited only by the appended claims.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure applies. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0016] The following detailed description illustrates various embodiments of the present subject matter and how they can be implemented. Although a limited number of exemplary methods and materials are described herein for clarity, those skilled in the art to which this disclosure is applicable will appreciate that other methods and materials for implementing or practicing the present subject matter are also possible.

[0017] 1. Definition As used herein, "RFID" refers to radio frequency identification device.

[0018] As used herein, an "RFID device" refers to a device that includes an antenna and an MTM array.

[0019] As used herein, an "RFID reader" refers to a device that includes one or more antennas that transmit radio waves and receive return signals from RFID devices.

[0020] As used herein, an "RFID tag" refers to a plaque including an RFID device that can be attached to a vehicle windshield to identify the vehicle at a toll plaza, parking lot or garage, gas station, or the like.

[0021] As used herein, "substrate" refers to a dielectric material. A dielectric material is a non-metallic substance with high specific electrical resistance.

[0022] As used herein, "negative magnetic permeability" refers to negative magnetic permeability when a material, in response to an applied magnetic field, forms a magnetic dipole in a direction opposite to the applied magnetic field.

[0023] As used herein, "gain" in the context of a transmitting antenna describes how effectively the antenna converts input power into radio waves traveling in a specified direction. In the context of a receiving antenna, gain describes how effectively the antenna converts radio waves from a specified direction into electrical power.

[0024] As used herein, "read range" refers to the maximum distance at which an RFID device can detect radio waves from an RFID reader. As long as the RFID device is within this range, it activates and allows the RFID reader to capture information.

[0025] As used herein, "directivity" refers to the ability of an antenna to focus radiation in a specific direction.

[0026] A "metamaterial" (MTM) is any material engineered to possess properties not found in naturally occurring materials. They are made from assemblies of multiple elements formed from composite materials, such as metals and plastics. These materials are typically arranged in repeating patterns at scales smaller than the wavelength of the phenomena they influence. MTMs derive their properties not from those of their substrates but from their newly engineered structures. Their precise shape, geometry, size, orientation, and arrangement give them intelligent properties capable of manipulating electromagnetic waves: blocking, absorbing, enhancing, or bending them to achieve benefits beyond those possible with traditional materials.

[0027] As used herein, "perimeter" refers to the boundary of a conductive material.

[0028] As used herein, an "antenna" refers to a conductor configured to transmit or receive electromagnetic radiation.

[0029] In the context of RFID readers, the term "reference point" refers to a starting or zero position that is used as a basis for measuring the angle of the RFID reader relative to an incoming vehicle and the direction of the road.

[0030] These and other features, aspects, embodiments, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. These definitions are provided to introduce a series of concepts in a simplified form. These definitions are not intended to identify key 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.

[0031] 2. Improved gain and directivity of RFID device antennas The RFID device disclosed herein is described in detail by way of example and with reference to the accompanying drawings. Unless otherwise indicated, like numbers in the drawings refer to like, similar, or corresponding elements throughout the figures. It should be understood that modifications to the disclosed and described examples, arrangements, configurations, components, elements, apparatuses, methods, materials, and the like are possible and may be desired for a particular application.

[0032] In this disclosure, any identification of specific shapes, materials, techniques, arrangements, etc., is either related to the specific examples presented or is a general description. Unless specifically specified, specific details or examples are not intended and should not be interpreted as mandatory or limiting.

[0033] In some embodiments, the present subject matter relates to an RFID device comprising an antenna and an MTM array. The antenna and the MTM array are both designed, constructed, and configured in such a manner that the RFID device utilizes the antenna and the MTM array together to enhance the gain and directivity of the antenna when exposed to incident radio waves from an RFID reader.

[0034] As used herein, an RFID device refers to a wireless identification device mounted on a vehicle (particularly on the windshield) to facilitate vehicle identification when interrogated by an RFID reader. In response to the interrogation, the RFID device transmits vehicle identification information (e.g., one or more identifiers) that allows a service provider to identify and debit an amount from an electronic wallet associated with the vehicle. As used herein, a nested slot refers to an antenna having multiple slots.

[0035] Figure 1 A schematic diagram of an RFID device 100 according to one embodiment is shown. The RFID device 100 for an RFID tag having both high gain and wide read range is described herein. The RFID tag includes the RFID device 100, an adhesive coating ( Figure 1 not shown) and a release liner ( Figure 1After removing the release liner, the RFID tag can be attached to the vehicle ( Figure 1 not shown), in particular attached to a windshield ( Figure 1 (not shown).

[0036] The RFID device 100 includes a substrate 101, an antenna 102, and an MTM array 105. The substrate 101 is 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 formed of a first conductive material that defines an area surrounded by a first perimeter 109 in a rectangular shape. The first conductive material may include a metal (e.g., aluminum or copper) or any other conductive material known in the art (e.g., conductive ink). The antenna 102 having a plurality of slots or nested slots 108 may be designed to have a specific shape and size to achieve desired electrical performance. The specific shape and size of the slots 108 may be created by performing a cutting operation on the first conductive material at different locations to form the antenna 102 (e.g., Figure 1 ). Furthermore, cutting can be accomplished via mechanical die cutting, etching, laser cutting, or any other suitable means to cut and subsequently remove unwanted material, such as nesting slots 108. Alternatively, if antenna 102 is formed by printing conductive ink, slots 108 can be formed by a pattern of printed ink, in which case cutting may not be necessary. Nesting slots 108 refer to openings or apertures that represent non-conductive portions of antenna 102. For example, when antenna 102 having nesting slots 108 is placed on a non-conductive or dielectric material (such as substrate 101), nesting slots 108 appear as non-conductive portions.

[0037] The MTM array 105 is formed of a second conductive material that defines an area surrounded by a rectangular-shaped second perimeter 110. The second conductive material can be the same as or different from the first conductive material used for the antenna 102. Figure 1 The MTM array 105 is formed as an MxN array 105 configuration. The MxN MTM array 105 includes a plurality of MTM cells 107. The plurality of MTM cells 107 are designed to have specific dimensions and geometric configurations, with careful consideration given to their impedance characteristics, to ensure compatibility with the antenna 102. The compatibility of the MTM array 105 and the antenna 102 is important because it ensures that the different components (i.e., the antenna 105 and the MTM array 105) can work together to achieve the desired results (e.g., maximize efficiency, etc.) and avoid potential problems that may be caused by mismatched or incompatible components. In the MxN array configuration, "M" indicates the number of rows, and "N" indicates the number of columns. The MxN MTM array 105 configuration includes a plurality of MTM cells 107. For example, Figure 1The plurality of MTM cells 107 are arranged in two rows and forty-three columns, i.e., a 2x43 MTM array configuration. The plurality of MTM cells 107 are formed on a second conductive material defining an area surrounded by a second perimeter 110 according to specific size and geometry, for example, by a cutting operation.

[0038] During the cutting operation, unwanted portions of the MTM array 105 configuration are selectively removed to achieve the desired geometry and dimensions. Furthermore, cutting can be accomplished via mechanical die cutting, etching, laser cutting, or any other suitable means to cut and subsequently remove unwanted material. Removing the unwanted material creates openings or apertures representing non-conductive portions of the MTM array 105. For example, the non-conductive portion can be air, an insulating material, or a dielectric material such as the substrate 101. The specific geometry of the MTM cells 107 includes the shape of the plurality of MTM cells 107. The shape of the plurality of MTM cells 107 can be, for example, square, rectangular, circular, triangular, or a combination thereof. Specific dimensions of the plurality of MTM cells 107 can include, but are not limited to, width and distance. For example, the width of the plurality of MTM cells 107 can include the width of the inner conductor and the width of the outer conductor, and the dimensions of the plurality of MTM cells 107 can include the distance between the inner and outer conductors and the distance between each of the plurality of MTM cells 107 and its corresponding one or more adjacent MTM cells 107. Alternatively, if the MTM cells 107 are formed by printing conductive ink, any openings or apertures can be formed by patterning the printed ink, in which case cutting may not be necessary. Antenna 102 includes a top surface 102a and a bottom surface 102b. The top surface 102a of antenna 102 is opposite the bottom surface 102b. The bottom surface 102b of antenna 102 and MTM array 105 are positioned on the first surface 101a of substrate 101, and are separated by gap 106. The elongated edge 112 of the second perimeter 110 of MTM array 105 is positioned parallel to the elongated edge 111 of the first perimeter 109 of antenna 102. The MTM array 105 and antenna 102 are coplanar with each other.

[0039] The substrate 101 is a dielectric material. The substrate 101 can be any dielectric material known in the art and can be selected for a particular antenna and / or intended application. The substrate can be, but is not limited to, a paper substrate or a polyethylene terephthalate (PET) substrate. The top surface 102a of the antenna 102 includes one or more feed point markers 103 and a chip 104. For example, the one or more feed point markers 103 are used to define a chip landing area. The chip 104 is electrically coupled to the antenna 102. For example, electrical coupling can be achieved by attaching the chip 104 directly to the antenna 102, or the chip 104 can be attached to the antenna 104 using a strip or using any electrical coupling technique known in the art. 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 signals from an RFID reader ( Figure 1 1. The antenna 102 is configured to receive an incident electromagnetic signal transmitted by an RFID reader (not shown). RF power is induced in the antenna 102 by the incident electromagnetic wave transmitted from the RFID reader. The antenna 102 is further configured to induce the RF power into the MTM array 105 via inductive coupling. In another embodiment, the antenna 102 is configured to induce the RF power into the MTM array 105 via capacitive coupling.

[0040] In an exemplary scenario, an RFID device 100 can be mounted on a vehicle windshield. RFID device 100 includes a substrate 101, an antenna 102, and an MTM array 105. Substrate 101 includes a first surface 101a and a second surface 101b. Antenna 102 and MTM array 105 are formed on first surface 101a of substrate 101. Second surface 101b of substrate 101 is opposite first surface 101a. Second surface 101b of substrate 101 also includes an adhesive coating and a release liner. To mount RFID device 100 on a vehicle's windshield, the release liner is removed and the RFID device 100 is attached to the windshield using the adhesive coating. The adhesive coating enables substrate 101 to adhere to the windshield. RFID readers can be installed at toll plazas, parking lots, gas stations, and the like. RFID device 100 on a vehicle can communicate with the RFID reader to provide vehicle identification information (e.g., one or more identifiers), which allows a service provider to identify and debit an amount from an electronic wallet associated with the vehicle. The RFID device 100 is configured to be read by an RFID reader when positioned at a specific angle, including a range of 30 to 90 degrees, thereby facilitating reliable retrieval of information from the attached RFID device 100. For example, an RFID reader with a 60-degree angle means that the RFID reader is positioned 60 degrees from a reference point.

[0041] Figure 2Aand Figure 2B A schematic diagram of a metamaterial (MTM) array 200 according to an embodiment is shown. The MTM array 200 according to the current embodiment includes a substrate 101 (eg, Figure 1 ) on a plurality of MTM cells 201. Each of the plurality of MTM cells 201 includes an inner conductor 204 and an outer conductor 203. The outer conductor 203 and the inner conductor 204 are formed on the first surface 101a of the substrate 101 (as shown). Figure 1 (as shown). The inner conductor 204 is positioned in the opposite direction from the outer conductor 203 and is located within the outer conductor 203. Each of the outer conductor 203 and the inner conductor 204 has a segmented square shape and is arranged with a predetermined distance g1 therebetween. Each of the plurality of MTM cells 201 is spaced apart from one or more corresponding adjacent MTM cells 201 by a predetermined distance g2. In the exemplary MTM array 200 configuration, the predetermined width W of the inner conductor 204 is 0.2 mm, the predetermined 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 corresponding adjacent MTM cells 201 is 0.4 mm. Each of the plurality of MTM cells 201 has a segmented square conductor, such as the inner conductor 204 and the outer conductor 203.

[0042] Antenna 102 (such as Figure 1 ) is configured to receive electromagnetic waves from an RFID reader (not shown in the figure). Return to Reference Figure 1Antenna 102 is excited in response to RF power induced by the incident electromagnetic wave. Furthermore, antenna 102 is configured to induce the RF power into MTM array 105 via inductive coupling. MTM array 105 responds to the induced RF power, and due to the excitation in both antenna 102 and MTM array 105, current is distributed in antenna 102 and MTM array 105, respectively. This current distribution contributes to a high overall current distribution in RFID device 100. Consequently, due to the high current distribution, RFID device 100 exhibits high radiation efficiency. This high current distribution in RFID device 100 is achieved by achieving impedance matching between the RFID reader and RFID device 100 (including antenna 102, chip 104, and MTM array 105). Impedance matching achieved in RFID device 100 is based on one or more factors, including but not limited to the antenna design or impedance network of antenna 102, the geometry and dimensions of MTM cells 107, the impedance characteristics of antenna 102 and MTM array 105, and the negative magnetic permeability of the MTMs. The impedance characteristics of both antenna 102 and MTM array 105 may include components related to resistance, capacitance, and inductance. The plurality of MTM cells 107 include a specific geometry (e.g., a segmented square ring) that, when excited by RF power, behaves as an LC (L-inductor and C-capacitor) resonant circuit, thereby providing negative permeability at its resonant frequency. For example, the resonant frequency may be any frequency that falls within the operating frequency range of an RFID device, such as the Federal Communications Commission (FCC) ultra-high frequency (UHF) RFID band, for example, ranging from 865 MHz to 868 MHz and 902 MHz to 928 MHz. The frequency values ​​of 865 MHz to 868 MHz and 902 MHz to 928 MHz are merely examples and should not be considered limiting, as different regions or countries authorize the use of different frequency bands. Those skilled in the art will appreciate that the use of MTM array 105 in the antenna 102 configuration improves overall RFID device 100 parameters such as radiation efficiency, gain, and directivity. The MTM array 105 with negative magnetic permeability enhances the properties of the antenna 102, such as directivity, gain, and radiation efficiency. Furthermore, the disclosed antenna 102 with the MTM array 105 design is capable of achieving complex impedance matching even when the RFID device 100 is attached to a high dielectric constant material, such as tempered glass commonly found in vehicle windshields.

[0043] Figure 3A and Figure 3B FIG. 1 shows a plan view of an RFID device 300 according to one embodiment. Figure 3A , the RFID device 300 includes one or more fragile areas 3a and 3b. For example, to attach the RFID device 300 to a vehicle windshield, a user removes the release liner ( Figure 3A and Figure 3B After removing the release liner, the adhesive coating of the RFID device 300 ( Figure 3A and Figure 3B Not shown) makes the substrate 101 (such as Figure 1 One or more fragile regions 3a and 3b may include fragile conductor materials, special adhesive formulations, etc. Figure 1 , a special adhesive formulation may be applied to the second surface 101b of the substrate 101. Each of the one or more frangible 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. The one or more frangible regions 3a and 3b extend across at least a portion of the antenna 301 and the MTM array 302, such that when the RFID device 300 breaks along the one or more frangible regions 3a and 3b, the RFID device 300 becomes unable to communicate with an RFID reader. The broken or tampered regions 4a and 4b of the RFID device 300 are Figure 3B Shown in.

[0044] Figure 4A and Figure 4B Shown according to one embodiment Figure 1 Example simulation results of the RFID device 100 are shown in FIG. Figure 4A The electric field strength of the antenna 102 without the MTM array 105 is shown. For example, the electric field strength of the antenna 102 without the MTM array 105 is about 7 V / m (volts per meter). Figure 4B The electric field strength of antenna 102 with MTM array 105 is shown. For example, the electric strength of antenna 102 with MTM array 105 is shown to be approximately 9 V / m. By using MTM array 105, the electric strength of RFID device 100 increases by approximately 2 V / m compared to using only antenna 102. Therefore, using MTM array 105 with antenna 102 enhances the gain and directivity of antenna 102.

[0045] Figure 5 Shown is a diagram showing a display according to an embodiment Figure 1 Graph of example read range results for the RFID device 100 shown in FIG. The electric field strength distribution on the antenna 102 and the RFID device 100 is shown in FIG. Figure 4A and Figure 4B The reading range of the RFID device 100 corresponding to the electric field strength distribution is shown in FIG. Figure 5When operating in the FCC UHF band, the read range is improved by 2 meters. The dashed line indicates the read range of antenna 102 without MTM array 105. The solid line indicates the read range of antenna 102 with MTM array 105. Compared to the read range of antenna 102 without MTM array 105, antenna 102 with MTM array 105 improves its read range by 2 meters.

[0046] Figure 6 Shown is a diagram showing a display according to an embodiment Figure 1 A graph of example gain results for the RFID device 100 is shown in FIG. Figure 6 The gain of the RFID device 100 including the antenna 102 and the MTM array 105 is shown.

[0047] However, it will be apparent to those skilled in the art that, without departing from the inventive concept herein, further modifications may be made in addition to those already described. Therefore, the subject matter of the present invention is not limited unless it accords with the spirit of the present disclosure. In addition, when interpreting the present disclosure, all terms should be interpreted in the broadest possible manner according to the context. In particular, the terms "comprise" and "comprising" should be interpreted as referring to elements, parts or steps in a non-exclusive manner, indicating that the referenced elements, parts or steps may exist, be used or be combined with other elements, parts or steps that are not explicitly referenced.

Claims

1. An RFID device, comprising: an antenna comprising a bottom surface and a top surface; Metamaterial array is MTM array; as well as a substrate of a flexible material having a first surface and a second surface, wherein the bottom surface of the antenna and the MTM array are formed on the first surface of the substrate, and The antenna and the MTM array are separated by a gap. 2 . The device of claim 1 , wherein the antenna is formed from a first conductive material, the first conductive material defining an area surrounded by a first perimeter. The device of claim 1 , wherein the antenna comprises a nesting slot. 4 . The device of claim 1 , wherein the MTM array is formed of a second conductive material, the second conductive material defining an area surrounded by a second perimeter. 5 . The apparatus of claim 1 , wherein the elongated edge of the second perimeter of the MTM array is disposed parallel to the elongated edge of the first perimeter of the antenna. The apparatus of claim 5 , wherein the antenna and the MTM array are coplanar with each other. The device of claim 1 , wherein a chip is disposed on the top surface of the antenna. The device of claim 7 , wherein the chip is electrically coupled to the antenna.

9. The apparatus of claim 1, wherein the antenna is inductively coupled to the MTM array.

10. The apparatus of claim 1, wherein the MTM array comprises an MxN array configuration. 11 . The apparatus of claim 10 , wherein the MxN MTM array configuration comprises 'M' MTM rows and 'N' MTM columns.

12. The apparatus of claim 11, wherein the MxN MTM array configuration comprises a plurality of MTM cells arranged in two rows and forty-three columns. 13 . The apparatus of claim 12 , wherein each of the plurality of MTM cells is spaced apart from corresponding one or more adjacent MTM cells by a predetermined distance.

14. The apparatus of claim 11, wherein the plurality of MTM cells have a shape selected from the group consisting of a square, a rectangle, a circle, and a triangle.

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

16. The apparatus of claim 1, wherein the substrate has an adhesive coating applied to the second surface of the substrate.

17. The device of claim 1, wherein the RFID device further comprises one or more frangible regions.

18. The device of claim 17, wherein each of the one or more frangible regions is defined at a predetermined distance from the chip, wherein the one or more frangible regions are configured to break upon an attempt to remove the attached RFID device.

19. The device of claim 18, wherein the one or more frangible regions extend across at least a portion of the antenna and the MTM array such that when the RFID device is broken along the one or more frangible regions of the RFID device, it is rendered incapable of communicating with an RFID reader.

20. The device of claim 1, wherein the RFID device is configured to be read by the RFID reader when positioned at a specific angle, the specific angle comprising a range of 30 degrees to 90 degrees from a reference point, thereby facilitating reliable functionality of retrieving information from the attached RFID device.

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