Substrate for rfid transponder with metal inlay

Abstract

The present invention relates to a substrate for an RFID transponder comprising: a carrier layer made of an insulating material; one or more metal inlays associated with the carrier layer; a main RFID antenna formed on the carrier layer and configured to communicate with an external electromagnetic reader; a compensation antenna formed on the carrier layer and configured to counteract the detuning effect of the one or more metal inlays and to enhance the communication of the main RFID antenna with the external electromagnetic reader. According to the present invention, the main RFID antenna and the compensation antenna can be formed on the same face of the carrier layer, or they can be not physically connected to each other, and / or they can be self-resonant antennas.

Description

Technical Field

[0001] This invention relates to the field of substrates for RFID transponders, and particularly to the field of substrates for RFID transponders comprising a metal frame, a metal plate, and an RFID antenna. Background Technology

[0002] In the prior art, RFID transponders (such as smart cards) that include a metal or metallized layer are known. Typically, adding a metal or metallized layer to a smart card makes it appear valuable, as if the entire smart card were made of metal.

[0003] However, since metals or metallization layers can detune the RFID antenna formed in the smart card, various modifications and / or additions are usually made to the smart card structure to counteract the detune effect during electromagnetic coupling in order to improve the coupling between the smart card and the external electromagnetic reader.

[0004] For example, patent application EP2807700 discloses a dual-interface smart card including an enhancement antenna and a metallized panel. The enhancement antenna has a coupler coil in the card body of the dual-interface smart card, and the metallized panel has a window for an antenna module with a modular antenna. In the dual-interface smart card of EP280770, attenuation caused by the metallized panel is reduced in various ways, such as by placing a ferrite element between the modular antenna and the contact pad in the antenna module, or by arranging the enhancement antenna as a quasi-dipole.

[0005] In the field of smart cards and RFID transponders, there is a need to continuously develop new solutions that can counteract the detuning effect of metal or metallization layers on the antenna during electromagnetic coupling and can be adapted to different configurations of RFID transponders, such as configurations that meet specific standards and requirements.

[0006] Therefore, the object of the present invention is to provide an RFID transponder in which the overall performance of the antenna is improved and the shielding effect of the metal layer is reduced. Summary of the Invention

[0007] The present invention is based on the idea of ​​providing a compensation antenna for the substrate used in RFID transponders to reduce detuning effects and enhance the performance of the main radio frequency identification (RFID) antenna.

[0008] According to a first aspect of the present invention, a substrate for an RFID transponder is provided, comprising:

[0009] -A carrier layer made of insulating material;

[0010] - One or more metallic inlays associated with the carrier layer;

[0011] - The main RFID antenna, which is formed on the carrier layer and configured to communicate with an external electromagnetic reader;

[0012] - A compensation antenna, formed on the carrier layer and configured to enhance communication between the main RFID antenna and an external electromagnetic reader.

[0013] The main RFID antenna and the compensation antenna are formed on the same surface of the carrier layer.

[0014] In this disclosure, it should be understood that the term "metal inlay" refers to any metal component, such as a metal plate or metal frame, that is partially or completely embedded in or formed on one or more faces of the carrier layer as a reinforcement.

[0015] In this disclosure, it should be understood that the term "metal frame" refers to an open shell or structure made to receive, enclose, or support a carrier layer. Preferably, the metal frame may enclose the carrier layer and one or more additional plastic layers such that the total thickness of the metal frame corresponds to the total thickness of the carrier layer and the additional layers.

[0016] In this disclosure, it should be understood that the term "compensating antenna" refers to any antenna that can be used to improve the transmit / receive performance of the main RFID antenna to an external electromagnetic reader and / or a module connected to an RFID transponder by compensating for the effects of eddy currents induced in one or more metallic inlays after exposure to the magnetic field of an external electromagnetic reader. For example, a compensating antenna can be used to maximize the magnetic flux associated with the main RFID antenna by inducing a current having the same flow direction as the induced current of the main RFID antenna. The compensating antenna can be an antenna inductively coupled to the main RFID antenna.

[0017] Preferably, the carrier layer is a card-shaped structure having a first side and a second side opposite to the first side. Alternatively, the carrier layer can have any shape suitable for accommodating the electronic components of an RFID transponder, and can have a first side and a second side opposite to the first side.

[0018] According to the present invention, the main RFID antenna and the compensation antenna are formed on the same surface of the carrier layer, for example, on the first surface or the second surface.

[0019] The advantage of this configuration is that the manufacturing process for both the main RFID antenna and the compensation antenna is simplified because they are formed on the same plane and in a single manufacturing step. For example, when forming the main RFID antenna and the compensation antenna using wire-embedding technology, if both antennas are formed on the same side, the wire-embedding process is simplified because a single wiring step is required.

[0020] Preferably, the compensation antenna is formed near the main antenna and the metal inlay to minimize the detuning effect of the metal inlay on the performance of the main antenna.

[0021] The carrier layer can be a single carrier layer or multiple carrier layers. Preferably, the insulating material can be any type of suitable plastic, such as various types of polymer materials (such as polycarbonate, PVC, etc.).

[0022] According to a second aspect of the present invention, a substrate for an RFID transponder is provided, comprising:

[0023] -A carrier layer made of insulating material;

[0024] - One or more metallic inlays associated with the carrier layer;

[0025] - The main RFID antenna, which is formed on the carrier layer and configured to communicate with an external electromagnetic reader;

[0026] - A compensation antenna, formed on the carrier layer and configured to enhance communication between the main RFID antenna and an external electromagnetic reader.

[0027] The main RFID antenna and the compensation antenna are not physically connected to each other.

[0028] The advantage of this configuration is that the main RFID antenna and the compensation antenna are separate and distinct antennas. On the other hand, if the compensation antenna were physically connected to the main RFID antenna, for example, via connecting wiring, the resulting antenna would be longer and would have increased resistance relative to the main RFID antenna.

[0029] According to a third aspect of the present invention, a substrate for an RFID transponder is provided, comprising:

[0030] -A carrier layer made of insulating material;

[0031] - One or more metallic inlays associated with the carrier layer;

[0032] - The main RFID antenna, which is formed on the carrier layer and configured to communicate with an external electromagnetic reader;

[0033] - A compensation antenna, formed on the carrier layer and configured to enhance communication between the main RFID antenna and an external electromagnetic reader.

[0034] Among them, the main RFID antenna and / or compensation antenna are self-resonance antennas.

[0035] In this disclosure, it should be understood that the term "self-resonant antenna" refers to a coil antenna that includes both inductive and capacitive portions.

[0036] The advantage of this configuration is that the capacitance portion of each self-resonant antenna can be used to fine-tune the antenna's resonant frequency. For example, the capacitance portion of the main RFID antenna can be used to fine-tune its resonant frequency. Similarly, the capacitance portion of the compensation antenna can be used to fine-tune its resonant frequency. In this way, the final resonant frequency of the system, including the compensation antenna inductively coupled to the main RFID antenna, can also be fine-tuned. For example, the final resonant frequency of the coupled system can be fine-tuned to match a predefined resonant frequency (such as the resonant frequency used for transaction operations), and predefined operations such as payments can be implemented.

[0037] In this disclosure, it should be understood that the substrate for an RFID transponder may include one or more aspects of the present invention. For example, the substrate of the present invention may include a main RFID antenna and a compensation antenna formed on the same side or side of the carrier layer. As an alternative or addition to the foregoing examples, the substrate of the present invention may include a main RFID antenna and / or a compensation antenna configured as self-resonant antennas. As an alternative or addition to the foregoing examples, the substrate of the present invention may include a main RFID antenna and a compensation antenna that are not physically connected to each other (e.g., they are not connected by wiring), and the main RFID antenna and the compensation antenna are inductively coupled to each other.

[0038] According to an embodiment of the first or third aspect of the present invention, a substrate is provided in which a compensation antenna is not physically connected to a main RFID antenna.

[0039] Preferably, the main RFID antenna and the compensation antenna are coil antennas comprising multiple windings. Preferably, the compensation antenna surrounds the main RFID antenna and is configured to be inductively coupled to the main RFID antenna. Preferably, the windings of the main RFID antenna are not physically connected to the windings of the compensation antenna. In this way, the connection between the main RFID antenna and the compensation antenna is entirely based on inductive coupling, rather than on an electrical connection carrying current. The advantage of this configuration is that it improves the cooperative performance between the two antennas compared to the case where a physical direct connection exists.

[0040] According to another embodiment of the first or second aspect of the present invention, a substrate is provided, wherein the main RFID antenna and / or compensation antenna are self-resonant antennas.

[0041] The advantage of this configuration is that the capacitance portion of each self-resonant antenna can be used to fine-tune the antenna's resonant frequency. For example, the capacitance portion of the main RFID antenna can be used to fine-tune its resonant frequency. Similarly, the capacitance portion of the compensation antenna can be used to fine-tune its resonant frequency. In this way, the final resonant frequency of the system, including the compensation antenna inductively coupled to the main RFID antenna, can also be fine-tuned. For example, the final resonant frequency of the coupled system can be fine-tuned to match a predefined resonant frequency (such as the resonant frequency used for transaction operations).

[0042] According to an alternative embodiment of the first or third aspect of the invention, a substrate is provided, wherein the main RFID antenna and the compensation antenna each include an inductive circuit or coil representing an inductive contribution to the RFID transponder, and each antenna is connected to one or more corresponding capacitors representing a capacitive contribution to the RFID transponder.

[0043] According to a preferred embodiment of the present invention, a substrate is provided, wherein the main RFID antenna and / or compensation antenna includes a first winding portion and a second winding portion, the first winding portion having a first winding direction, and the second winding portion having a second winding direction opposite to the first winding direction of the first winding portion, wherein the first winding portion forms an inductor coil of the main RFID antenna and / or compensation antenna, and the second winding portion forms a capacitor coil of the main RFID antenna and / or compensation antenna.

[0044] The advantage of this configuration is that each coupled antenna is equipped with a second winding that acts as a capacitor, connected in series with the first winding, which acts as an inductor. In this way, there is no need to connect an additional capacitor to the antenna for fine-tuning its resonant frequency. Therefore, production costs are reduced and the manufacturing process is simplified.

[0045] According to another embodiment of one or more aspects of the present invention, a substrate is provided in which a main RFID antenna and a compensation antenna are concentric with each other, and the compensation antenna is formed around the main RFID antenna.

[0046] The advantage of this configuration is that it optimizes the space occupied by the antenna on the card-type substrate and maximizes the enhancement effect of the compensation antenna on the main RFID antenna.

[0047] According to another embodiment of the present invention, a substrate is provided, wherein the metal inlay includes a metal plate formed within a carrier layer.

[0048] For example, metal plates can be formed on or inside the carrier layer to increase the weight of the card substrate and give it a more valuable configuration.

[0049] According to a preferred embodiment of the present invention, a substrate is provided in which a main RFID antenna and a compensation antenna are formed on the periphery of a metal plate.

[0050] The advantage of this configuration is that it reduces electromagnetic interference between the coupled antenna and the metal plate.

[0051] According to another embodiment of the present invention, a substrate is provided, wherein the metal inlay includes a metal frame formed along the periphery of a carrier layer.

[0052] For example, the metal frame can be formed along the edge of the carrier layer having a card-like structure. Preferably, the metal frame can be shaped to leave uncovered portions of the carrier layer on a first surface and a second surface of the carrier layer opposite to the first surface.

[0053] According to a preferred embodiment of the present invention, a substrate is provided in which a main RFID antenna and a compensation antenna are formed within the periphery of a metal frame.

[0054] The advantage of this configuration is that it reduces electromagnetic interference between the coupled antenna and the metal frame.

[0055] According to another aspect of the present invention, an RFID transponder is provided, comprising:

[0056] -The substrate as described above;

[0057] - An electronic module coupled to the main RFID antenna;

[0058] - One or more layers of insulating material attached to the substrate.

[0059] The advantage of this configuration is that the communication between the RFID transponder and the external electromagnetic reader is improved due to the presence of the compensating antenna, which enhances the signal of the main RFID antenna. For example, the reading range of the RFID transponder can be increased.

[0060] In this disclosure, it should be understood that the phrase "electronic module coupled to the main RFID antenna" can refer to both a configuration inductively coupled to the main RFID antenna and a configuration in which the electronic module is directly electrically connected to the main RFID antenna. For example, the electronic module can be a contact module for operating the RFID transponder in contact mode, or a dual-interface module for operating the RFID transponder in both contact and contactless modes.

[0061] Preferably, the substrate further includes an auxiliary coupling antenna, which is inductively coupled to the electronic module and positioned on the carrier layer corresponding to the position occupied by the electronic module in the final RFID transponder. Preferably, the auxiliary coupling antenna is inductively coupled to both the electronic module and the main RFID antenna to enable communication between the electronic module and an external electromagnetic reader. Alternatively, the auxiliary coupling antenna can be inductively coupled to the electronic module and electrically connected to the main RFID antenna to enable communication between the electronic module and an external electromagnetic reader. Therefore, the inductive coupling between the main RFID antenna and the electronic module can be direct inductive coupling or indirect inductive coupling (i.e., inductive coupling via the auxiliary coupling antenna).

[0062] According to another aspect of the present invention, a method for operating the above-described substrate is provided, the method comprising the following steps:

[0063] - Expose the substrate to an electromagnetic field generated by an external reader;

[0064] - A main induced current with a first direction is generated within the main RFID antenna through inductive coupling with an electromagnetic field;

[0065] -Eddy currents with a second direction opposite to the first direction are generated in the metal inlay through inductive coupling with the electromagnetic field.

[0066] - An additional induced current is generated within the compensation antenna through inductive coupling with an electromagnetic field, wherein the additional induced current has the same direction as the first direction and is configured to enhance the communication response between the main RFID antenna and an external reader.

[0067] The advantage of this method is that it enables operation of the substrate according to the invention. Attached Figure Description

[0068] In the following description, with reference also to the accompanying drawings, other exemplary embodiments and other aspects of the invention will be described in more detail, in which:

[0069] Figure 1A A top view of a substrate according to an embodiment of the present invention is schematically illustrated;

[0070] Figure 1B An equivalent circuit of an electronic system including a main antenna and an auxiliary antenna for an electronic module, according to an embodiment of the present invention, is illustrated schematically.

[0071] Figure 2A A top view of a substrate according to another embodiment of the present invention is schematically illustrated;

[0072] Figure 2BAn equivalent circuit of an electronic system including a main antenna and an electronic module according to an embodiment of the present invention is illustrated schematically.

[0073] Figure 3 A top view of a substrate according to the prior art is schematically illustrated;

[0074] Figure 4 The direction of the induced current in the substrate according to an embodiment of the present invention is schematically illustrated;

[0075] Figure 5 A diagram illustrating the reflection coefficient of a coupled antenna formed in a substrate according to an embodiment of the present invention is shown schematically.

[0076] Figure 6 A top view of a substrate according to an alternative embodiment of the invention is schematically illustrated. Detailed Implementation

[0077] The invention is described below with reference to specific embodiments illustrated in the accompanying drawings. However, the invention is not limited to the specific embodiments described in the following detailed description and shown in the figures. Rather, the described embodiments are merely illustrative of different features of the invention, the scope of which is defined in the claims. Further modifications and variations of the invention will be apparent to those skilled in the art.

[0078] In the following detailed description, the terms “right,” “left,” “top,” “bottom,” and their variations are used with reference to the orientation shown in the figures.

[0079] Figure 1A The substrate 100 includes a carrier layer 102, which can typically include any type of suitable plastic, such as various types of polymer materials (such as polycarbonate, PVC, etc.).

[0080] Figure 1A The substrate 100 includes two metal inlays that give the substrate 100 additional weight and make it look more precious, as if the entire substrate were made of metal.

[0081] Figure 1A The metal inlay of the substrate includes a frame 120 and a metal plate 110. The frame 120 is physically connected to the carrier layer 102 and is formed around the edge of the carrier layer 102. Preferably, the frame 120 is a continuous frame formed entirely around the edge of the carrier layer 102. Preferably, the frame 120 is designed such that most of the top and bottom surfaces of the carrier layer 102 are not covered. Preferably, the thickness of the frame 120 is greater than the thickness of the carrier layer 102, such that the frame 120 can accommodate other layers (such as additional plastic layers) attached to the carrier layer 102.

[0082] The metal plate 110 is a metal component formed on a portion of the carrier layer 102. Preferably, the shape and size of the metal plate 110 are designed to occupy an area of ​​the carrier layer not occupied by electronic components such as the main RFID antenna 140, the auxiliary coupling antenna 130 for the electronic module, and the compensation antenna 150. Preferably, the thickness of the metal plate 110 may be greater than the thickness of the carrier layer 102, and it may protrude from the carrier layer 102. Preferably, one or more additional plastic layers may be attached to the carrier layer 102 in the portion not occupied by the metal plate 110 to form a surface flush with the surface of the protrusion of the metal plate 102.

[0083] Preferably, the substrate 100 of the present invention does not include any additional layers such as a ferrite layer for shielding the metal plate 110 from the influence of the main RFID antenna 140.

[0084] According to some embodiments, the substrate 100 of the present invention may correspond to card-type information substrates 100 and / or 200A / 200B, respectively including frames 110 and 210, as referenced in the international application WO2021 / 074680 by the same applicant. Figure 1A , Figure 1B , Figure 2A and Figure 2B The information substrate 100 and / or 200A / 200B of the card type are disclosed in detail, and the contents of the international application are incorporated herein by reference in their entirety.

[0085] According to some embodiments, the substrate 100 of the present invention may correspond to a preform 690 including a frame 610 and a metal-containing plate 680, as described in the international application WO2021 / 074680 by the same applicant, see reference to Figure 6 A- Figure 6 J discloses the preform 690 in detail, the contents of which are incorporated herein by reference in their entirety.

[0086] Figure 1A The substrate 100 includes a main RFID antenna 140 for enabling communication between an external electromagnetic reader and an electronic module of an RFID transponder (not shown).

[0087] Continue to refer to Figure 1A The substrate 100 also includes an auxiliary antenna 130 that is inductively coupled to the electronic module of an RFID transponder (not shown).

[0088] like Figure 1A As shown and in Figure 6As shown in more detail, the main RFID antenna 140 is electrically connected to the auxiliary coupling antenna 130 for the electronic module via wiring section 144. In this way, when the electronic module including the chip is added to the RFID transponder in correspondence with the auxiliary coupling antenna 130, the main RFID antenna 140 can communicate with the electronic module.

[0089] Figure 1B The illustration shows, for example Figure 1A The simplified equivalent circuit of the electronic system shown includes the main RFID antenna 140 and the auxiliary coupling antenna 130 for the electronic module (coil resistance is ignored).

[0090] like Figure 1B As schematically shown, the main RFID antenna 140 can be approximated by a first inductor L1, and the auxiliary coupling antenna 130 for the electronic module can be approximated by a second inductor L2. Since the main RFID antenna 140 and the auxiliary coupling antenna 130 for the electronic module are connected via wiring 144, the main RFID antenna 140 also includes a portion with a reverse winding direction: this portion has reverse current flow and can be approximated by a capacitor C1 added to the main RFID antenna 140. Figure 1B As shown in the schematic circuit, plates A and B of capacitor C1 with opposite charges can be obtained through the coiled portion of the main RFID antenna 140 with opposite winding directions, as referenced. Figure 6 As explained.

[0091] Therefore, the equivalent circuit of the electronic system, including the main RFID antenna 140 and the auxiliary coupling antenna 130 for the electronic module, includes a first inductor and a second inductor connected in series with the capacitor C1.

[0092] Figure 1A The substrate 100 also includes a compensation antenna 150, which will be described in detail below, for enhancing the communication performance of the main RFID antenna 140.

[0093] The main RFID antenna 140 and the compensation antenna 150 are advantageously formed on the same surface of the carrier layer 102 to improve their inductive coupling. (Reference) Figure 1A The substrate 100, the main RFID antenna 140 and the compensation antenna 150 are formed on the top surface of the carrier layer 102.

[0094] Preferably, Figure 1A The main RFID antenna 140 and the compensation antenna 150 can be self-resonant antennas.

[0095] like Figure 1AAs shown, the compensation antenna 150 may include a capacitive element C to fine-tune its resonant frequency and enable communication with the main RFID antenna 140 and an external electromagnetic reader. The capacitive element C may be a capacitor (such as a surface-mount capacitor), or as shown in the reference... Figure 6 The capacitive coil 152 under discussion.

[0096] Continue to refer to Figure 1A The main RFID antenna 140 and the compensation antenna 150 are formed within the outline of the metal frame 120.

[0097] Continue to refer to Figure 1A The main RFID antenna 140 and the compensation antenna 150 are formed outside the outline of the metal plate 110.

[0098] like Figure 1A As shown, when viewed from the main direction, the main RFID antenna 140, the auxiliary coupling antenna 130 for the electronic module, and / or the compensation antenna 150 do not include any portion overlapping with the metal frame 120 or the metal plate 110. In this way, electromagnetic interference between the coupling antennas 140 and 150 and the metal frame 120 and the metal plate 110 is minimized.

[0099] The main RFID antenna 140, the auxiliary coupling antenna 130 for the electronic module, and the compensation antenna 150 can be formed by embedding wiring on the carrier layer 102. According to an alternative embodiment, the main RFID antenna 140, the auxiliary coupling antenna 130 for the electronic module, and the compensation antenna 150 can be formed by other manufacturing techniques such as printing, etching, laser etching, coil winding, or conductive material deposition.

[0100] Figure 2A A top view of a substrate according to another embodiment of the present invention is schematically illustrated.

[0101] Figure 2A substrate 100 and Figure 1A Corresponding to the substrate, and differing in the configuration of the connection between the main RFID antenna 140 and the electronic module 160, which includes electronic chips. In fact, in Figure 2A In the substrate 100, the electronic module 160 is directly connected to the main RFID antenna 140, instead of... Figure 1A In the configuration, it is indirectly connected to the main RFID antenna 140 via inductive coupling. For example... Figure 2A As shown, the winding direction of the main RFID antenna 140 is the same as the direction of the electrical connection between the main RFID antenna 140 and the electronic module 160.

[0102] Figure 2B The illustration illustrates the following: Figure 2AThe illustrated embodiment includes the equivalent circuit of the electronic system comprising the main antenna 140 and the electronic module 160.

[0103] like Figure 2B As illustrated, the main RFID antenna 140 can be approximated by a first inductor L1, and the electronic module 160 can be approximated by a capacitor C2.

[0104] Therefore, the equivalent circuit of the electronic system including the main RFID antenna 140 and the electronic module 160 includes a first inductor L1 connected in series with the capacitor C2.

[0105] like Figure 2B As shown in the schematic circuit, capacitor C2 can be obtained through the chip capacitor of the electronic module.

[0106] For the purpose of comparison, Figure 3 A top view of a substrate 100′ according to the prior art is schematically illustrated.

[0107] The substrate 100' according to the prior art corresponds to the substrate 100 of the present invention in that it includes a carrier layer 102' made of insulating material, a metal frame 120' and a metal plate 110' associated with the carrier layer 102', and a main RFID antenna 140' formed on the carrier layer 102' and configured to communicate with an external electromagnetic reader.

[0108] However, the substrate 100' according to the prior art does not include a compensation antenna configured to enhance communication between the main RFID antenna 140' and the external electromagnetic reader. Therefore, the communication between the main RFID antenna 140' and the external electromagnetic reader in the prior art is weak, for example, having a short communication range.

[0109] During operation of the substrate 100 of the present invention, the main RFID antenna 140 generates a magnetic flux that powers the electronic module of the RFID transponder (not shown) and is used to transmit messages between an external reader and the electronic module. Therefore, a requirement for the main RFID antenna 140 is that its induced current is maximized after communication with the external reader, so that the corresponding magnetic flux is also maximized.

[0110] However, the magnetic flux associated with the induced current of the main RFID antenna 140 is reduced due to the formation of eddy currents within the metal inlay (such as the metal frame 120 and the metal plate 110). In fact, the eddy currents formed within the metal inlay can have a flow direction opposite to that of the induced current corresponding to the main RFID antenna 140.

[0111] The concept is Figure 4The diagram schematically shows that the induced current of the main RFID antenna 140 has a first direction D1, and the eddy currents in the metal frame 120 and the metal plate 110 have opposite directions D2.

[0112] In this regard, it should be understood that the term “eddy current” refers to any undesirable current associated with any physical mechanism that results in a loss of electromagnetic radiation transmitted or received by the main RFID antenna 140 due to the presence of a metallic inlay (such as a metal frame and / or metal plate).

[0113] Therefore, the present invention is based on the idea of ​​adding a compensating antenna 150 with a winding direction that allows the induced current to flow in the same direction as the first direction D1. In this way, the magnetic flux associated with the main RFID antenna 140 is maximized, and communication with an external reader is improved. For example, the reading range of an RFID transponder including the substrate 100 of the present invention can be increased.

[0114] According to a preferred embodiment, the compensation antenna 150 can be inductively coupled to the main RFID antenna 140. Preferably, the compensation antenna 150 is not physically connected to the main RFID antenna 140.

[0115] According to other preferred embodiments, the main RFID antenna 140 and the compensation antenna 150 can be advantageously formed on the same surface of the carrier layer 102 to improve their inductive coupling and simplify the antenna manufacturing process.

[0116] According to other preferred embodiments, Figure 1A The main RFID antenna 140 and the compensation antenna 150 can be self-resonant antennas to ensure fine-tuning of the resonant frequency of the system comprising two coupled antennas 140 and 150.

[0117] Preferably, both the main RFID antenna 140 and the compensation antenna 150 are radio frequency (RF) antennas and can be used to operate radio frequency identification (RFID) devices, such as RFID transponders (e.g., RFID smart cards for payment). Therefore, the improved communication performance of the main RFID antenna 140 can be either improved communication in the radio frequency field or improved RF performance.

[0118] The communication performance of the main RFID antenna 140 when inductively coupled to the compensation antenna 150 can be described by different physical parameters. An exemplary physical parameter associated with the antenna's RF performance is the antenna reflection coefficient, which quantifies the level of the incident waveform of the reflected electromagnetic field, or the strength reduction due to coupling to the standardized coupling coil according to the standardized process used to evaluate RF performance. These physical parameters are also known as S-parameters.

[0119] Figure 5 The S-parameters of the main RFID antenna 140 and the compensation antenna 150 according to an embodiment of the present invention are schematically illustrated in a frequency range including 8 MHz and 20 MHz. Figure 5 As shown, the main RFID antenna 140 has a resonant frequency between 13MHz and 20MHz, particularly between 14MHz and 14.5MHz. Preferably, the compensation antenna has a resonant frequency between 14MHz and 20MHz. Preferably, the target resonant frequency for RF communication with the RFID transponder is between 12MHz and 18MHz.

[0120] Continue to refer to Figure 5 When enhanced by the compensation antenna 150, the main RFID antenna 140 has a resonant frequency included between 14MHz and 21MHz.

[0121] from Figure 5 It is evident that the RF performance of the main RFID antenna 140 is improved when coupled with the compensation antenna 150. In fact, the S-parameter value for measuring energy loss decreases, for example, from -1 dB to -1.25 dB. In other words, the S-parameter value of the main RFID antenna including the compensation antenna is lower than that of the main RFID antenna without the compensation antenna.

[0122] Figure 6 A top view of a substrate 100 according to an alternative embodiment of the present invention is schematically illustrated.

[0123] exist Figure 6 In the substrate 100, the main RFID antenna 140 and the compensation antenna 150 respectively include capacitor elements 142 and 152.

[0124] like Figure 6 As schematically shown, the main RFID antenna 140 includes coiled wiring 146 having a first winding direction that starts from point A and ends in the auxiliary coupling antenna 130 for the electronic module (reference). Figure 6 The exemplary orientation of the substrate shown is from left to right. The winding direction is defined by the flow of induced current when exposed to an electromagnetic field perpendicular to the plane defined by the substrate 100 and entering the substrate 100.

[0125] Corresponding to the auxiliary coupling antenna 130 for the electronic module, the intersection 144 of the wiring of the main RFID antenna 140 intersects with the coiled wiring 146 of the auxiliary coupling antenna 130 for the electronic module and the main RFID antenna 140.

[0126] After the intersection 144, the wiring of the main RFID antenna 140 is wound in the opposite direction to the previous coiled wiring 146. Since opposite charges are obtained at opposite ends of the reversed portion, capacitance is generated in the main RFID antenna 140.

[0127] In a similar way, such as Figure 6 As schematically shown, the compensation antenna 150 includes a first winding direction starting from point C (reference). Figure 6 The illustrated substrate shows a coiled wiring 156 (from right to left) with an illustrative orientation. The winding direction is defined by the flow of induced current when exposed to an electromagnetic field perpendicular to the plane defined by the substrate 100 and entering the substrate 100.

[0128] and Figure 6 Corresponding to the lower right corner of the substrate 100, the intersection 154 of the wiring of the compensation antenna 150 intersects with the coiled wiring 156 of the compensation antenna 150.

[0129] After the intersection 154, the winding of the wiring of the compensation antenna 150 is reversed relative to the previous coiled wiring 156. Since opposite charges are obtained at the opposite ends of the reversed portion, a capacitance is generated in the compensation antenna 150.

[0130] Therefore, adjacent wirings with the same winding direction (and the same current flow direction) represent the inductor portions (or inductor coils 146 and 156) of the main RFID antenna 140 and the compensation antenna 150, respectively.

[0131] On the other hand, adjacent wirings with opposite winding directions (and opposite current flow directions) relative to the inductor coils 146 and 156 of the main RFID antenna 140 and the compensation antenna 150 respectively represent the capacitor portions (or capacitor coils 142 and 152) of the main RFID antenna 140 and the compensation antenna 150.

[0132] Capacitor coils 142 and 152 can be advantageously used in the main RFID antenna 140 and the compensation antenna 150 to tune the resonant frequency of each coupled antenna (and thus tune the combined resonant frequency of the two coupled antennas) to match a predefined frequency for operational purposes, such as matching a predefined frequency of an external reader for transaction operations.

[0133] Although the present invention has been described with reference to the above embodiments, those skilled in the art will understand that various modifications, variations and improvements can be applied to the present invention based on the above teachings and the field of knowledge, and within the scope of the appended claims, without departing from the scope and purpose of the present invention.

[0134] For example, it should be understood that although the main RFID antenna 140 and the compensation antenna 150 are shown in the drawings as being formed on the same surface of the carrier layer 102, according to an alternative embodiment (not shown), the main RFID antenna 140 and the compensation antenna 150 may also be formed on different sides of the carrier layer 102.

[0135] Finally, areas that a person skilled in the art would consider known are omitted to avoid covering the described invention in a useless way.

[0136] Figure Labels

[0137] 100: Substrate

[0138] 102: Carrier layer

[0139] 110: Metal plate

[0140] 120: Metal frame

[0141] 130: Auxiliary coupling antenna for electronic modules

[0142] 140: Main RFID antenna

[0143] 142: Capacitor coil of the main RFID antenna

[0144] 144: Cross-wiring of the main RFID antenna

[0145] 146: Inductor coil of the main RFID antenna

[0146] 150: Compensation Antenna

[0147] 152: Capacitor coil of the compensation antenna

[0148] 154: Cross wiring of compensated antennas

[0149] 156: Inductor coil of the compensation antenna

[0150] 160: Electronic Module

[0151] 100': Substrate according to the prior art

[0152] 102': Carrier according to existing technology

[0153] 110': Metal plate according to the prior art

[0154] 120': Metal frame according to the prior art

[0155] 130': Auxiliary coupling antenna for electronic modules according to the prior art

[0156] 140': Coupled antenna according to the prior art

[0157] D1: First direction of induced current

[0158] D2: Second direction of induced current

[0159] L1, L2: Inductors

[0160] C1, C2: Capacitors

Claims

1. A substrate (100) for an RFID transponder, comprising: -A carrier layer (102) made of insulating material; - One or more metal inlays (110, 120) associated with the carrier layer (102); - A main RFID antenna (140) is formed on the carrier layer (102) and configured to communicate with an external electromagnetic reader; A compensation antenna (150) is formed on the carrier layer (102) and configured to enhance communication between the main RFID antenna (140) and the external electromagnetic reader. The main RFID antenna (140) and the compensation antenna (150) are formed on the same surface of the carrier layer (102).

2. A substrate (100) for an RFID transponder, comprising: -A carrier layer (102) made of insulating material; - One or more metal inlays (110, 120) associated with the carrier layer (102); - A main RFID antenna (140) is formed on the carrier layer (102) and configured to communicate with an external electromagnetic reader; A compensation antenna (150) is formed on the carrier layer (102) and configured to enhance communication between the main RFID antenna (140) and the external electromagnetic reader. The main RFID antenna (140) and the compensation antenna (150) are not physically connected to each other.

3. A substrate (100) for an RFID transponder, comprising: -A carrier layer (102) made of insulating material; - One or more metal inlays (110, 120) associated with the carrier layer (102); - A main RFID antenna (140) is formed on the carrier layer (102) and configured to communicate with an external electromagnetic reader; A compensation antenna (150) is formed on the carrier layer (102) and configured to enhance communication between the main RFID antenna (140) and the external electromagnetic reader. The main RFID antenna (140) and / or the compensation antenna (150) are self-resonant antennas.

4. The substrate (100) according to claim 1 or 3, wherein, The compensation antenna (150) is not physically connected to the main RFID antenna (140).

5. The substrate (100) according to claim 1, 2 or 4, wherein, The main RFID antenna (140) and / or the compensation antenna (150) are self-resonant antennas.

6. The substrate (100) according to any one of the preceding claims, wherein, The main RFID antenna (140) and / or the compensation antenna (150) include a first winding portion (146, 156) and a second winding portion (142, 152). The first winding portion (146, 156) has a first winding direction, and the second winding portion (142, 152) has a second winding direction opposite to the first winding direction of the first winding portion. The first winding portion (146, 156) forms the inductor coil of the main RFID antenna (140) and / or the compensation antenna (150), and the second winding portion forms the capacitor coil of the main RFID antenna (140) and / or the compensation antenna (150).

7. The substrate (100) according to any one of the preceding claims, wherein, The main RFID antenna (140) and the compensation antenna (150) are concentric with each other, and the compensation antenna (150) is formed around the main RFID antenna (140).

8. The substrate (100) according to any one of the preceding claims, wherein, The metal inlay includes a metal plate (110) formed on or inside the carrier layer (102).

9. The substrate (100) according to any one of the preceding claims, wherein, The metal inlay includes a metal frame (120) formed along the periphery of the carrier layer (102).

10. The substrate (100) according to claim 8, wherein, The main RFID antenna (140) and the compensation antenna (150) are formed on the periphery of the metal plate (110).

11. The substrate (100) according to claim 9, wherein, The main RFID antenna (140) and the compensation antenna (150) are formed within the periphery of the metal frame (120).

12. An RFID transponder, such as a smart card, comprising: The substrate (100) according to any one of claims 1 to 11; - An electronic module coupled to the main RFID antenna (140); - One or more layers of insulating material are attached to the substrate (100).

13. A method for operating a substrate (100) according to any one of claims 1 to 11, comprising the following steps: - Expose the substrate (100) to an electromagnetic field generated by an external reader; -A main induced current with a first direction (D1) is generated in the main RFID antenna (140) by inductive coupling with the electromagnetic field; -Eddy currents with a second direction (D2) opposite to the first direction (D1) are generated within the metal inlay (110, 120) by inductive coupling with the electromagnetic field; - An additional induced current is generated within the compensation antenna (150) by inductive coupling with the electromagnetic field, wherein the additional induced current has the same direction as the first direction (D1) and is configured to minimize the detuning effect of the one or more metal inlays (110, 120) and enhance the communication response between the main RFID antenna (140) and the external reader.

Images