CHIPLOSE RFID LABEL

Description

[0001] The present invention relates to a chipless (personalized) radio frequency identification (“RFID”) device, in particular a chipless (personalized) RFID tag, also called a “chip-less RFID tag”.

[0002] The term "device" should be understood to mean packaging, a document, including a security document, and possibly any object containing the RFID tag without the claimed chip.

[0003] Data transmission systems using radio frequency identification (RFID) technology are commonly used to identify all types of objects and living beings (e.g., animals or humans) carrying a suitable device (tag). RFID technology has become increasingly widespread over the past few decades as a device for storing and transmitting information.

[0004] This RFID technology uses a radio tag, also called a transponder (from the English "transponder," a contraction of the words "transmitter" and "responder"), which is attached to an object, and a reader, also called an interrogator, to read and identify the tag. RFID technologies are generally classified into categories using "active" or "passive" tags. Active tags have a local power source (such as a battery) through which they send a signal to the reader; they are thus generally characterized by a relatively long signal range.In contrast, passive radio tags do not have an internal power source because their signal transmission energy comes from the reader itself, and in particular from the reception of the signal emitted by the reader; thus, passive radio tags have a much shorter signal range, generally less than 8 meters.

[0005] From a practical standpoint, RFID technology uses radio frequencies (“RF”) which have much higher material penetration characteristics than optical signals. Thus, compared to barcode labels, RFID technology allows for use in far more hostile environmental conditions; for example, RFID tags can be read through all kinds of materials such as paper, cardboard, wood, paint, water, dirt, dust, animal or human bodies, concrete, or even through the tagged item itself or its packaging. This has opened up a wide range of applications for RFID tags, including, for example, the identification of goods and people, particularly packaging, and vehicles (parking, tolls, etc.).), inventory management, electronic access cards, not forgetting all security documents such as, for example, a means of payment, such as a banknote, a check or a restaurant voucher, an identity document, such as an identity card, a visa, a passport or a driver's license, a lottery ticket, a transport ticket or even an entry ticket to cultural or sporting events.

[0006] There are mainly two types of RFID tags, tags including an integrated electronic circuit, called chip (electronic) tags, and tags not including an integrated electronic circuit, generally referred to in the technical field by the English term "chip-less RFID tags".

[0007] RFID tags (active or passive) typically include an antenna, an electronic circuit, and memory to store an identification code. The electronic circuit receives the signal emitted by the reader and, in response, transmits a modulated signal containing the identification code stored in memory within a specific frequency band. For passive RFID tags, some of the energy carried by the radio waves emitted by the reader is used to power the chip.

[0008] Due to the presence of electronic circuits in chip-based RFID tags, these tags have a significant production cost. It is primarily to reduce this cost that the development of chipless tags has been proposed. This type of chipless RFID tag requires neither integrated circuits nor discrete electronic components, such as transistors, inductors, capacitors, and / or antennas; their conductive geometric characteristics generate a specific behavior, notably a resonant one. This resonance characteristic at a given frequency allows chipless RFID tags to be printed directly onto an object at a lower cost than traditional RFID tags.

[0009] Increasing the coding capacity of chipless radio frequency identification devices, as well as the manufacturing of these devices and, in particular, the industrial manufacturing of discriminating devices, constitute important challenges in the state of the art.

[0010] In "Microsystems Technologies" (volume 24, pages 4373 - 4382 (2018)), Zhong-Hua Ma, Jian-Hong Yang, Chih-Cheng Chen and Cheng-Fu Yang propose a retransmitted chip-free tag based on a high-Q CSRR structure operating on the UWB frequency band, which is proposed, which consists of two microstrip broadband monopole antennas transmitting and receiving orthogonal polarization, loaded with several CSRR resonators.In the experimental part of this article, in chapters 6 and 7, a Rogers 4350 type dielectric substrate is used primarily (with a relative dielectric constant of 3.66, a loss tangent of 0.004 and a thickness of 0.508 mm - several thicknesses are also tested (0.3, 0.508 and 0.8 mm, respectively); this dielectric substrate is then replaced respectively by a plastic substrate (with a relative dielectric constant of 3.1, a loss tangent of 0.008 and a thickness of 1 mm) as well as by foam (relative dielectric constant of 1.06, loss tangent of 0.0015 and thickness of 1 mm, the only conclusion drawn from these changes being that "the output spectrum correctly indicates the state of the coding" without further indication.

[0011] In the publication "2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), Conference: 7-13 July 2013, IEEE Xplore: 27 January 2014, INSPEC Accession Number: 14058155, DOI: 10.1109 / APS.2013.6711573, pages 1828-1829", Peixeiro Custodio presents high-efficiency microstrip patch antenna elements developed within the framework of a European Union research project on "green radio" technology. figure 1 This represents a configuration of stacked patches coupled to a broadband aperture with substrates consisting of three layers of Rogers Duroid 5880 and a 10 mm thick foam layer. These antennas do not have the same function / utility as the chipless tags of the present invention – therefore, the design challenges are different.

[0012] In [IEEE Access ( Volume: 7) / Page(s): 138707 - 138720 / Publication Date: 14 August 2019 / Electronic ISSN: 2169-3536 / INSPEC Accession Number: 19088375 / DOI: 10.1109 / ACCESS.2019.2935258] Svanda Milan et al. describe "High-capacity dipole plate chipless RFID tags". In the last paragraph of section III relating to the topology of 20-Bit chipless RFID tag, it is stated that the substrate consists of Rogers RO4350 (relative dielectric constant of 3.66, loss tangent of 0.003 and thickness of 0.1 mm) and a layer of foam (relative dielectric constant of 1.3, loss tangent of 0.02 and thickness of 1 mm).

[0013] In the publication [2019 IEEE International Conference on RFID Technology and Applications (RFID-TA) - Date of Conference: 25-27 Sept. 2019 - INSPEC Accession Number: 19135523 - pages 174-177], Laura Corchia et al. describe "A Chipless Humidity Sensor for Wearable Applications", i.e., humidity sensors for clothing.

[0014] In an article published in IEEE Transactions on Microwave Theory and Techniques (Pages: 4547 - 4558 of Volume: 67, Issue: 11, Nov. 2019 - "Scalar Method for Reading of Chipless RFID Tags Based on Limited Ground Plane Backed Dipole Resonator Array"), Jan Kracek describes a scalar method for reading chipless RFID tags. This publication describes in Figure 9(a) a chipless RFID tag consisting of a dipole resonator array with a ground plane and comprising as intermediate layers a 0.1 mm thick RO4350 substrate (Rogers-type dielectric) with a relative permittivity of 3.66 and a loss angle tangent of 0.003, and a 1 mm thick foam layer inserted between the ground plane and the substrate, with a relative permittivity of 1.3 and a loss angle tangent of 0.02.

[0015] EP3537855 (A1) relates to a chipless radio frequency identification (“RFID”) device and the manufacture of chipless RFID labels.

[0016] Although chipless RFID technology shows great promise, efforts are still underway to improve the read performance of these tags. Read performance refers to the tag's ability to be read and identified, for example, by increasing the tag's signal level (the useful signal carrying the tag's information) relative to other signals such as measurement noise or signals backscattered by other objects near the tag. Specific work on the tag itself, particularly the materials used in its construction, is essential to address the challenges of read performance, as well as the manufacturing and cost of these tags. The materials used to construct the tags will have a direct impact on the useful signal backscattered by the tag. Invention

[0017] Thus, the present invention provides a promising solution to this problem by proposing new chipless (personalized) radio frequency identification (“RFID”) devices, in particular chipless (personalized) RFID tags, also called “chip-less RFID tags”.

[0018] The invention is defined in independent claim 1. Particular embodiments are defined in dependent claims 2-23.

[0019] In particular, the present invention relates to chipless radio frequency identification devices, preferably chipless RFID tags, characterized in that they comprise a particular dielectric substrate surmounted by pattern(s) made of a layer of conductive material; preferably a dielectric substrate made of solid foam, foam board, corrugated board, honeycomb board or fabric (for example, a material made of interlaced yarns or fibers of cotton, hemp, linen or synthetics such as nylon, polyamide or viscose), surmounted by pattern(s) made of a layer of conductive material.

[0020] As described in more detail in the following description, solid foam is preferably understood to be a dielectric material which may be rigid or flexible, which contains a significant percentage of air or gas balls and which therefore, while occupying a certain volume, contains very little matter in the solid state, the solid state preferably being a state of matter characterized by the absence of freedom between molecules or ions; thus, a foam is generally characterized by a very low relative permittivity, namely close to 1, 1 being the value of the permittivity of air.

[0021] Indeed, the applicant unexpectedly discovered that this dielectric substrate and conductive pattern assembly according to the present invention made it possible to obtain devices that not only exhibited optimal resonance characteristics but also superior radiation efficiency and read performance; thus, it is at least the sum of the two layers, dielectric and conductive pattern, that defines the resonance characteristics of the device according to the invention. This discovery opens up a vast field of new applications for chipless RFID tags because, as demonstrated in this application, it is possible to easily identify the corresponding devices (their RF signature remaining recognizable) while also facilitating their manufacture.This is all the more unexpected and counterintuitive because it was known in the field that preserving the surface conductive properties of the tag was a manufacturing requirement to ensure the tag retained a usable radio frequency signature. This is even more unexpected and counterintuitive because it was known in the field that the presence of a substrate with high permittivity improves the tag's resonance capacity (increasing the quality factor of the tag's resonators). Indeed, the higher the substrate's permittivity, the more the field is stored in the dielectric near the conductive layers, and the better the resonance (increasing the quality factor). A high quality factor is known to be a fundamental criterion for a reader's ability to read the tag in a real-world environment, namely one containing objects other than the RFID tag.The higher the quality factor, the more it will be possible to temporally separate the signal emitted by the tag from the environment signal, which allows for a correct measurement of the tag, and this is therefore the configuration sought in practice.

[0022] Within the framework of the present invention, the use of the qualifier "personalized" for the claimed devices / labels simply confirms that the identification / discrimination of the device / label is possible. Dielectric substrate

[0023] The chipless RFID devices / tags according to the present invention are therefore characterized in that they comprise a particular dielectric substrate.

[0024] This particular dielectric substrate will advantageously be selected from among dielectric substrates meeting at least one of the following conditions: an apparent density less than 250 kg.m⁻³; for example, less than 100 kg.m⁻³; and / or a relative permittivity less than 3; preferably less than 2; preferably less than 1.25. For example, this relative permittivity will be less than 1.10. In a particular embodiment according to the present invention, this relative permittivity will be close to 1. This relative permittivity will preferably be greater than 1.001. For example, this relative permittivity will be greater than 1.01; and / or a loss angle tangent value less than 10⁻², preferably less than 10⁻³, for example, less than 2.10⁻⁴.

[0025] This particular dielectric substrate will advantageously be selected from among solid foam dielectric substrates, foam board, corrugated board, honeycomb board or fabric dielectric substrates (for example in a material made of interlaced yarns or fibers of cotton, hemp, linen or synthetics such as nylon, polyamide or viscose).

[0026] This dielectric substrate will advantageously be rigid or flexible; it will preferably be in the form of a film.

[0027] The thickness of the dielectric substrate will advantageously be greater than 0.1 mm. This thickness will preferably be greater than 0.5 mm. For example, this thickness will be greater than 0.75 mm.

[0028] The thickness of the dielectric substrate will advantageously be less than 3 mm. This thickness will preferably be less than 1.5 mm. For example, this thickness will be less than 1.25 mm.

[0029] Any dielectric substrate meeting the reading, resonance, and discrimination performance objectives of the present invention may advantageously be used within the scope of the present invention. Examples include fabric (for example, a material made of interlaced yarns or fibers of cotton, hemp, linen, or synthetics such as nylon, polyamide, or viscose), corrugated cardboard, honeycomb cardboard, foam board, solid foam, for example, polymers or biopolymers.

[0030] In a particular embodiment of the present invention, the dielectric substrate is characterized by its apparent density, which is less than 250 kg / m³; for example, less than 100 kg / m³. The apparent density can be measured by any suitable method, for example, by weighing. Unless otherwise specified, densities are given for materials at a temperature of 20 °C under normal atmospheric pressure (1013 hPa). It may also be advantageous to use any ASTM or ISO method applicable to the type of material selected as the dielectric substrate for measuring this apparent density; regardless of the ASTM or ISO method chosen (and applicable to the type of material selected), the measurement of the apparent density will therefore preferably be less than 250 kg / m³; for example, less than 100 kg / m³.

[0031] In a particular embodiment of the present invention, the dielectric substrate is characterized by its dielectric properties, namely a relative permittivity of less than 3, preferably less than 2. This relative permittivity will preferably be less than 1.25. For example, this relative permittivity will be less than 1.10. In a particular embodiment of the present invention, this relative permittivity will be close to 1. This relative permittivity will preferably be greater than 1.001. For example, this relative permittivity will be greater than 1.01.

[0032] In a particular embodiment according to the present invention, the dielectric substrate is characterized by its dielectric properties, namely a loss angle tangent value less than 10⁻², preferably less than 10⁻³, for example less than 2.10⁻⁴.

[0033] As a reminder, dielectric permittivity is a physical property that describes the response of a material when an electric field is applied to it; and the tangent of the loss angle is also called the dielectric dissipation factor.

[0034] The relative permittivity and loss angle tangent (tan δ) can be measured by any suitable method. For example, dielectric spectroscopy or resonant cavity spectroscopy are commonly used dielectric analysis techniques. These techniques are based on measuring the complex impedance of a sample at a given frequency and / or temperature. The present invention relates to applications at temperatures around ambient temperature (typically between -20°C and +80°C). Within this temperature range, the permittivity and dielectric losses of commonly found dielectric materials can be considered relatively constant, particularly in the band of interest, which is the ULB band between 3 GHz and 10 GHz.

[0035] This method allows access to the permittivity value of a material or its loss factor tan δ at a given frequency, for example. The values ​​indicated in this description and the following claims correspond to those measured at any frequency within the frequency band from 3 GHz to 10 GHz, at a temperature of 20°C.

[0036] In particular, the values ​​shown in the following examples were measured using the Damaskos Model 08 ("Thin Sheet Tester - Cavity"), which provides an excellent estimate of the dielectric permittivity of dielectric substrates. This Damaskos thin sheet tester also provides a non-destructive measurement of the dielectric loss tangent in the 800-4000 MHz band, making it particularly well-suited to our substrates. The measurement is performed on common vector and scalar analyzers under the control of the Damaskos equipment, and the data is processed using the "Cavity" software sold by Damaskos, resulting in very good repeatability. Solid foam

[0037] Solid foam (for example, polymer foam) is a solid foam used, for example, in many applications such as thermal insulation, acoustic insulation, packaging, automotive, etc. This foam can be likened to a continuous solid network containing trapped gas bubbles (usually air), which allows it to combine the properties of a foam (density, lightness) with those of a solid.

[0038] Solid foam can advantageously be characterized by its nature, density, closed or open cell structure, bubble size, and the arrangement of said bubbles in space.

[0039] A solid foam is considered low-density when it contains more than 90% gas, corresponding to an apparent density of less than 100 kg / m³. A medium-density foam has an apparent density between 100 and 600 kg / m³. Finally, a high-density solid foam contains less than 60% gas, corresponding to an apparent density greater than 600 kg / m³. Apparent density can be measured by any appropriate method, for example, by weighing. Unless otherwise specified, densities are given for substances at a temperature of 20 °C and under normal atmospheric pressure (1013 hPa).

[0040] The solid foam used in the context of the present invention will preferably have an apparent density of less than 250 kg.m⁻³. For example, it will have an apparent density of less than 100 kg.m⁻³.

[0041] The solid foam used in the context of the present invention will preferably have a bubble density between 10⁴ and 10⁹ bubbles / cm³. For example, it will have a bubble density between 10⁵ and 10⁸ bubbles / cm³.

[0042] The solid foam used in the context of the present invention will preferably have a bubble size with an average diameter of between 5 microns and 1 millimeter. For example, it will have an average diameter of between 20 microns and 200 microns.

[0043] Any material exhibiting the foam characteristics claimed within the scope of the present invention may advantageously be selected. Examples include foam board, polymers, and biopolymers. A polymer is generally understood to be a structure composed of several macromolecules (molecules made up of the repetition of numerous subunits); generally, a material is considered a polymer when its molar mass exceeds 2,000 g / mol.

[0044] In a particular embodiment of the present invention, the solid foam shall be a polymer foam, for example, a polymer selected from thermosets such as polyurethanes, epoxies, etc., or, preferably, from thermoplastics such as polystyrene, polyvinyl chloride, polypropylene, polyethylene, polyethylene terephthalate (PET), and / or a mixture of one or more of these polymers. A foam comprising more than 80% by weight, for example, more than 90% by weight, of polyethylene (PE) or polyethylene terephthalate (PET) shall advantageously be selected within the scope of the present invention.

[0045] The morphology of foams, particularly bubble size and density, can be determined by any appropriate method. For example, the foam (e.g., polymer foam) is fractured under liquid nitrogen to position itself below the polymer's glass transition temperature. Since the fracture surface is clean, the bubbles are not deformed and can be observed, for instance, by microscopy. Preferably, an electron microscope coupled with image analysis software capable of counting the number of bubbles and calculating the average bubble area for each image is used. This allows the average bubble diameter to be determined, as well as the equivalent average diameter when the bubbles are not spherical. The bubble density (the number of bubbles per cm³) is determined by the formula (n / A)(3 / 2), where n is the number of bubbles in the image and A is the image area.

[0046] Polymer foam can be prepared by any suitable method. We will cite by way of illustration physical foaming with gas injection (for example CO2 or dinitrogen (N2)) or chemical foaming with addition and decomposition of a blowing agent (for example 5-Phenyltetrazole, p-Toluene sulfonyl semicarbazide, Dinitrospoenta-methylenetetramine, p-Toluene sulfonyl hydrazide, pp-Oxybis(benzene)sulfonyl hydrazide and / or Azodicabonamide which is preferentially used).

[0047] An extrusion blow molding process is particularly suitable for the preparation of a polymer foam film that can be used in the context of the present invention.

[0048] Nucleating agents can advantageously be added to the polymer, making it possible to obtain small bubbles. Examples include inorganic fillers (e.g., stearic acids, calcium stearate, zinc stearate, calcium carbonate, magnesium silicate, talc, sodium benzoate), organic phases such as elastomers and / or rubber particles, carbon black, and / or nanoparticles such as nano clays or carbon nanoparticles (e.g., nanotubes).

[0049] In a particular embodiment of the present invention, the solid foam will be selected from foam boards, also known as foam board; this type of material generally consists of three layers, including a main inner layer of polymer foam (for example, polystyrene, polyurethane, polyethylene, and / or polyethylene terephthalate (PET)) covered on the outside with a thin film, for example, paper or plastic. The type of paper or plastic representing the optional top layer of the dielectric substrate surmounted by pattern(s) made of a layer of conductive material is not critical, as it represents a negligible thickness compared to that of the solid foam, as explained in detail below.

[0050] In general, and in a particular embodiment according to the present invention, the dielectric substrate (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) with its characteristics as described herein and / or claimed represents at least 95% by volume and / or 95% by thickness and / or 95% by weight of the entire dielectric substrate on which the pattern(s) consisting of a layer of conductive material is / are affixed, preferably at least 99% by volume and / or 99% by thickness and / or 99% by weight of the entire dielectric substrate on which the pattern(s) consisting of a layer of conductive material is / are affixed.The present invention therefore also relates to a chipless RFID tag consisting of a dielectric substrate which is itself made up of a dielectric substrate with its characteristics as described and / or claimed herein surmounted by a thin dielectric layer on which is / are affixed the pattern(s) made up of a layer of conductive material; this thin dielectric layer (for example a film of paper or cardboard or of plastic material (for example: a film of polyethylene (PE), polypropylene (PP) or preferably polyethylene terephthalate (PET)) therefore advantageously represents less than 5%, or even less than 1% of the thickness of the entire dielectric substrate.

[0051] Although seemingly optional and not critical, the Applicant found that this thin dielectric layer or dielectric film provided many additional benefits to the claimed RFID tag subject to a few preferred requirements.

[0052] First, it is important to mention that the relative permittivity and loss angle tangent values ​​of the corresponding dielectric stack of the claimed label will always have values ​​that meet the claimed characteristic values; the influence of the additional dielectric film on the dielectric assembly will therefore be insignificant compared to these criteria.

[0053] Next, and this represents a considerable advantage of an embodiment according to the present invention, the Applicant found that the flatness and / or surface condition of the dielectric surface on which the conductive pattern was affixed could also represent an additional problem in the production of the label; indeed, as it frequently happens that the upper layer of the main dielectric (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) of the label does not have good flatness and / or a good surface condition, the use of an additional dielectric film made it possible to obtain better results / performance because, among other things, it provided this flatness and / or surface condition required.Thus, by applying the pattern(s) consisting of a layer of conductive material directly onto this dielectric film, improved performance has been achieved. Any appropriate method may be used to characterize the flatness and / or surface condition of the conductive film. By way of illustration, and to avoid having to consider measurements that are difficult to implement, the claimed labels will advantageously be characterized by a total thickness at any point on the label that varies from less than one hundred (100) microns, preferably less than fifty (50) microns, for example, less than forty (40) microns, less than twenty (20) microns, less than ten (10) microns, or even, for example, less than two (2) microns.The application of the pattern(s) consisting of a layer of conductive material directly onto this dielectric film can be carried out by any appropriate method as explained below in the description, for example by printing, for example by inkjet printing.Next, the dielectric film covered with the pattern(s) made of a layer of conductive material can be added to the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) in any direction / order; the Applicant even found an advantage in carrying out the successive stacking (1) main dielectric substrate - (2) conductive pattern - (3) dielectric film - because this stacking made it possible to advantageously protect the conductive patterns during the handling and / or use of the label since these patterns were protected both on one side by the main dielectric substrate and on the other side by the dielectric film.

[0054] In a particular embodiment, the dielectric film is characterized by one, two, or more of the following characteristics: a relative permittivity measured at any frequency between 3 and 10 GHz higher than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a relative permittivity greater than 1.25, for example greater than 2; preferably a relative permittivity less than 3.5; and / or a loss angle tangent value measured at any frequency between 3 and 10 GHz higher than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a loss angle tangent value less than 2.10 -2< ; and / or a thickness at least ten times less than that of the main dielectric substrate (solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam); preferably a thickness less than 100 microns, for example less than 50 microns; and / or made of plastic material, for example polyethylene, polypropylene or polyethylene terephthalate. .

[0055] In a particular embodiment, the main chemical composition of the dielectric film is identical to that of the main dielectric substrate. For example, if the main dielectric substrate is polyethylene terephthalate foam, the additional dielectric film will also be polyethylene terephthalate-based. Cardboard

[0056] As previously stated, the dielectric substrate according to the present invention may, by way of illustration, be selected from corrugated cardboard or honeycomb cardboard. By way of illustration, corrugated cardboard will be selected from B-flute cardboard (also called PC, generally with a thickness between 2.5 and 3.5 mm), E-flute cardboard (also called micro-flute, generally with a thickness between 2 and 1.5 mm); F-flute cardboard (also called Minimicro, generally with a thickness of about 1.2 mm), G-flute or N-flute cardboard (called Nano-flute) with a thickness of about 0.8 mm, O-flute cardboard with a thickness of about 0.5 mm, or a mixture of two or more of the aforementioned cardboards.

[0057] The cardboard used in the context of the present invention will preferably have an apparent density of less than 250 kg.m⁻³. For example, it will have an apparent density of less than 100 kg.m⁻³.

[0058] In a particular embodiment of the present invention, the chipless RFID tag consisting of a dielectric substrate surmounted by pattern(s) made of a conductive layer is characterized in that the upper part of the dielectric substrate is in contact with the pattern(s) made of a conductive layer. Indeed, in addition to the advantages related to the flat / smooth surface of the upper part of the dielectric substrate mentioned above, the Applicant has also discovered that it is preferable to avoid the presence of any other material between these two layers (substrate / optional film / conductive patterns); for example, no adhesive is used between these two parts of the tag. Conductive layer

[0059] The chipless radio frequency identification devices, preferably chipless RFID tags, according to the present invention are characterized in that they comprise a specific dielectric substrate surmounted by pattern(s) consisting of a layer of conductive material. In a particular case specific to the present invention, the chipless radio frequency identification devices, preferably chipless RFID tags, also comprise one or more layers of conductive material beneath the dielectric substrate; preferably covering the entire surface of the dielectric substrate. The configuration comprising two conductive layers, one beneath the dielectric substrate and the pattern(s) above the dielectric substrate, is a particularly advantageous case for the invention (dielectric substrate sandwiched between the two conductive layers), as explained below in the description of tags with a ground plane.

[0060] In a particular embodiment according to the present invention, the material of the conductive layer constituting the pattern comprises (or preferably consists of) a material selected from the group consisting of graphite, copper, nickel, silver, aluminum, platinum and / or mixtures thereof, preferably copper and / or silver and / or aluminum.

[0061] In a particular embodiment of the present invention, the conductive layer constituting the pattern is characterized by a thickness of conductive material greater than 100 nm. For example, a thickness of more than 150 nm may be used. For example, a thickness of more than 200 nm may be used. For example, a thickness of more than 250 nm may be used. For example, a thickness of more than 300 nm may be used. For example, a thickness of more than 400 nm may be used. For example, a thickness of more than 500 nm may be used.

[0062] In a particular embodiment of the present invention, the conductive layer constituting the pattern is characterized by a conductive material thickness of less than 20 microns. Preferably, the conductive material thickness will be less than 10 microns, or even less than 2 microns. For example, a thickness of less than 1.5 microns may be used.

[0063] The conductive material layer can be deposited, preferably directly onto the dielectric substrate or onto the optional dielectric film, by any suitable deposition method.

[0064] According to the present invention and in a particular manufacturing embodiment, the dielectric substrate is generally in the form of a rectangular or square film, for example, a thick sheet or a thin film in the optional embodiment using a dielectric film. This sheet (or film) moves, generally by means of a substrate transport system in a printing machine, along a transport path oriented along a longitudinal axis from at least one input magazine supplying said printable and / or customizable substrates to at least one output magazine receiving the printed and / or customized substrates, and thus covered with the conductive material patterns according to the present invention. The "lateral edges" of the substrate are the two edges located on either side of this longitudinal axis; the front and / or rear edges are its transverse edges.The substrate can also be in the form of a reel in a reel-to-reel type machine.

[0065] We will cite, by way of illustration, as a suitable method for manufacturing the claimed device / tag, a method for printing conductive ink, in particular a method for digitally printing conductive ink, and more specifically a method for digitally printing conductive ink using on-demand inkjet printing. This on-demand inkjet printing of conductive ink preferably uses piezoelectric printheads.

[0066] We will also cite, by way of illustration, as a suitable alternative method for depositing a pattern consisting of a layer of conductive material, a method that comprises a digital printing step of a first pattern consisting of a printing product, preferably dielectric, such as an ink, varnish, and / or toner, followed by a step of depositing, by overlaying on the first printed pattern, an identical pattern consisting of a conductive film comprising an application film in contact with the printing product and a conductive film. We will cite, by way of illustration, any digital printing method as a suitable method for the printing step of the first pattern, more particularly a digital on-demand jet printing method. This on-demand jet printing preferably uses piezoelectric printheads.For example, the step of applying the film to the first pattern is carried out under pressure and temperature conditions resulting in selective co-adhesion between the printing product and the film application film, for example by means of one or more sets of pinch rollers and / or one or more pressure rollers.

[0067] We will also cite, by way of illustration, as a suitable alternative method for the method of depositing a pattern consisting of a layer of conductive material, a method by thermal transfer of the conductive material.

[0068] We will also cite, as an illustrative alternative method for creating the tag, the method of successively assembling films together. This involves creating a conductive film (for example, a cut aluminum layer with an illustrative thickness of 5 to 20 µm) which can be deposited onto an optional transport film (for example, PET) before or after cutting, followed by a foam layer and then another conductive film (for example, an aluminum layer). The films / layers can be held together with a suitable adhesive; however, a wrapping or welding method as described below is preferred because it eliminates the need for adhesive.From a schematic illustrative point of view, this corresponds to a tag production which is characterized by the production of 2 "complex" layers and a cutting step; for example, a "complex" metal layer (represented in the illustrations below by the example of aluminium) ALU / PET is produced with glue: . -------- ALUMINUM -------- with an illustrative thickness of 5 to 20 µm ------- Adhesive -------- -------- PET --------

[0069] Then this layer will be cut to create the tags. Next, the final "complex" metal layer (represented in the illustrations below by the example of aluminum) must be created: FOAM / ALUMINUM: ---- FOAM ---- -------- ALUMINUM --------

[0070] Finally, these two complex layers must be assembled to form the tags: -------- ALUMINUM -------- with an illustrative thickness of 5 to 20 µm ------- Adhesive -------- -------- PET -------- ---- FOAM ---- -------- ALUMINUM --------

[0071] We will also cite, as an illustration, a suitable alternative method for creating the tag involving the production of two "complex" layers and a chemical reaction step. First, a "complex" metal layer (represented in the illustrations below by the example of aluminum) ALU / PET must be produced: -------- ALUMINUM -------- with a thickness of 5 to 20 µm (tested at 12 µm) ------- Adhesive -------- (optional) -------- PET --------

[0072] Then a protective varnish is applied to form the design of the tag on the aluminum face (the varnish only protects the aluminum used for the tag).

[0073] Next, this varnish layer will be immersed in a chemical bath that will remove the aluminum not protected by the varnish. After that, the final "complex" metal layer (represented in the illustrations below by the example of aluminum) must be applied: FOAM / ALUMINUM: ---- FOAM ---- -------- ALUMINUM --------

[0074] Finally, these two complex layers must be assembled to form the tag; an illustration of the corresponding successive layers is shown below: ----- VARNISH ------ representing the tag -------- ALUMINUM -------- representing the tag with a thickness of 5 to 20 µm ------- Adhesive -------- (optional) -------- PET -------- ---- FOAM ---- -------- PET -------- ------- Adhesive -------- (optional) -------- ALUMINUM --------

[0075] Using aluminum tape is also an option for making a tag. Simply cut it to create the conductive designs, which are then glued onto the chosen, suitable substrate.

[0076] We will also cite, as an example, as a suitable and preferred alternative method for tag production, the method of successively assembling the label layers by wrapping or welding their ends. In this particular method, the objective is to eliminate the use of adhesive between the successive contact surfaces of the RFID label layers while ensuring close contact between these surfaces; any means suitable for achieving this dual objective can be advantageously used. The layer-wrapping technique, which maintains contact between the surfaces of said layers, has been successfully tested.A welding technique at the ends of the layers (near the outer edges of the label) has also been successfully implemented; by way of illustration, this welding can advantageously be carried out using a reel-to-reel type device by means of which the stacked layers of the previously wound labels will be unwound and then welded at the appropriate places to capture and assemble the labels without the need to cut the main dielectric substrate (e.g. solid foam) beforehand.

[0077] Thus, and this constitutes a preferred embodiment according to the present invention, the chipless RFID tag will be formed successively from bottom to top of an optional but preferred conductive layer, surmounted by an optional but preferred dielectric film, surmounted by the main dielectric substrate (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam), surmounted by a dielectric film on which is affixed the pattern(s) consisting of a layer of conductive material, said conductive patterns being able to be located either on the upper part of the label, or advantageously between the main dielectric substrate and the dielectric film.

[0078] The present invention therefore relates to a device, preferably a tag, which has resonance characteristics. In a particular embodiment according to the present invention, the claimed tag consists of the claimed dielectric substrates and the claimed conductive layers. Tag

[0079] By way of illustration, the chipless (personalized) RFID tag according to the present invention has the following characteristics: • A conductive pattern or set of conductive patterns characterizing its geometry, preferably with at least one or more or all of the asymmetrical patterns, • An identifier that includes at least one resonance frequency fr and, preferably, at least one Q quality factor, ∘ Resonant in an ultra-wideband (ULB) frequency range characterized by a bandwidth greater than or equal to 500 MHz, preferably between 3.1 and 10.6 GHz, ∘ With or without a ground plane, and ∘ Polarizing or preferably Depolarizing. Tag - Geometry

[0080] Thanks to the coding possibilities offered by the claimed method, the Applicant has also developed a whole range of new tag families. Thus, in a particular mode, a tag will preferably be composed of at least one pattern, preferably at least two asymmetric patterns. For example, the Figure 1 shows the tags with site plan created specifically within the framework of the present invention. This Figure 1 The illustration shows four tags, each with six resonators. Two families of resonators (double L shape - in dark gray - and double parallel line shape inclined at 45° - in light gray) are used to optimize tag performance. The frequency band in which the resonance frequencies of each tag lie is indicated in the lower left corner of each tag. Different tag geometries are shown, created in accordance with the claimed method. Tag - Identifier

[0081] The tag according to the present invention will preferably be characterized by an identifier that includes at least one resonance frequency fr and at least one quality factor Q. Resonant Tag

[0082] The tag according to the present invention is therefore resonant in an ultra-wide frequency band (ULB) characterized by a bandwidth greater than or equal to 500 MHz, preferably between 3.1 and 10.6 GHz. Passive Tag

[0083] As explained in the introduction, our type of chipless radio frequency identification device requires neither an integrated circuit nor discrete electronic components, such as a transistor, coil, capacitor, or antenna. This type of device is therefore characterized by passive behavior, as it does not require a local power source (such as a battery).

[0084] As a reminder, the term "device" means packaging, a document, a label, including a security document, and possibly any object and / or living being on which RFID identification marking without a chip can be carried out or on which a marking medium can be attached. Tag with or without site plan

[0085] The tag according to the present invention can be characterized in that it has or does not have a ground plane. In its simplest expression, a tag with a ground plane according to the present invention is defined as a structure comprising a flat dielectric substrate with a thickness generally less than 3 mm and generally greater than 100 µm sandwiched between two metallic layers (the conductive pattern layer above the dielectric substrate and the other conductive layer located below the dielectric substrate).

[0086] For illustrative purposes, the thickness of the conductive layer located under the substrate will be advantageously selected from the following thicknesses.

[0087] In a particular embodiment of the present invention, the conductive layer located beneath the substrate is characterized by a thickness of conductive material greater than 100 nm. For example, a thickness of more than 150 nm may be used. For example, a thickness of more than 200 nm may be used. For example, a thickness of more than 250 nm may be used. For example, a thickness of more than 300 nm may be used. For example, a thickness of more than 400 nm may be used. For example, a thickness of more than 500 nm may be used.

[0088] In a particular embodiment of the present invention, the conductive layer located beneath the substrate is characterized by a conductive material thickness of less than 20 microns, for example, less than 10 microns, or even less than 2 microns. A thickness of less than 1.5 microns may be used, for example. A thickness of less than 1 micron may also be used.

[0089] In a particular embodiment according to the present invention, the total of the layers (conducting motif - dielectric - conductive layer) may, for example, have a thickness of 0.1 to 3 mm.

[0090] Although we talk about tagging with or without a ground plane, in the technique, the term "ground plane" is often associated with the metallic layer (located under the substrate) whose surface preferably corresponds totally to that of the substrate.

[0091] In a particular embodiment of the present invention, the material of the conductive layer constituting the ground plane comprises (or preferably consists of) a material selected from the group consisting of graphite, copper, nickel, silver, aluminum, platinum, and / or mixtures thereof, preferably copper and / or silver and / or aluminum. In another particular embodiment of the present invention, the material of the conductive layer constituting the ground plane is different from or identical to that of the conductive pattern, preferably identical.

[0092] Will the second metallic layer (the pattern(s)) be shaped to present a particular geometric form corresponding to the patterns of the tag (like the patterns shown on the figure 1A tag with a ground plane is therefore a structure comprising two metallic layers, while its counterpart without a ground plane has only one layer, namely the one where the tag's design is created. A tag with a ground plane has the advantage, once positioned with the ground plane facing an object, of electromagnetically isolating the tag from the object. In this case, the object's influence on the tag is less compared to a tag without a ground plane.

[0093] It should also be noted that a tag with a ground plane is a special case of a tag with two metallized layers where the substrate is sandwiched between them. In this preferred configuration, one of the two layers is ideally fully metallized. However, intermediate tag configurations are possible. For example, a tag with ground planes has openings (removals of metallic areas) made on the ground plane side to achieve specific behavior. This can, for instance, create new resonances or modify those already present on the first conductive layer. These openings can also promote the isolation of the different resonators in the second metallic layer, thus improving the decoupling of these resonances and potentially enhancing the tag's read performance.

[0094] The conductive material layer of the ground plane can be deposited, preferably directly onto the dielectric substrate, by any suitable deposition method. The deposition methods mentioned above for the deposition of conductive patterns will be repeated as an illustration.

[0095] It should also be noted that a chipless tag with two conductive layers and a dielectric layer in between can, for cost reasons, also be made by surrounding the substrate with the conductive layers, for example by folding. In this case, the conductive layer can have a surface area at least twice that of the substrate, typically a width at least twice as large with the same length. Once this surface, containing the conductive patterns and / or the ground plane, is fabricated, it is advantageously transferred all at once around the dielectric layer. This is possible by folding it completely around the surface. The only difference compared to the traditional approach (transferring the two metallized layers one by one to each face of the dielectric) is the presence of the metallized layer on one or more sides of the dielectric.If this part is not metallized, there is no significant difference compared to the more traditional approach. However, the possibility of metallizing this part (one or more sides of the dielectric) will allow for the creation of more complex structures, such as a resonant cavity with metallic walls, which will improve the quality factor. Thus, a skilled professional can take advantage of this structure, which is also generally simpler to manufacture because it requires fewer steps. Indeed, this approach reduces the number of technological steps: printing a single conductive substrate and bonding a single substrate.

[0096] In a particular application mode according to the present invention, the dielectric substrate (with or without a ground plane) will be selected from commercial materials used for thermal or acoustic insulation whose characteristics correspond to those claimed in the present invention; and the desired conductive patterns will be applied directly to these commercial materials.

[0097] The present invention is therefore advantageously applicable to tags both with and without a ground plane. Depolarizing tag

[0098] The tag according to the present invention will preferably be characterized by the fact that it is polarizing or, preferably, depolarizing. A depolarizing tag is a tag capable of emitting a wave with a polarization oriented perpendicular to that incident (this is then referred to as cross-polarization reflection).

[0099] In a particular embodiment according to the present invention, the chipless RFID tag has a ratio between the total upper surface of the dielectric substrate and the upper surface of the dielectric substrate covered with pattern(s) consisting of a layer of conductive material greater than 2.

[0100] In a particular embodiment according to the present invention, the chipless RFID tag with ground plane has a ratio between the lower surface of the dielectric substrate covered with the conductive material layer and the total lower surface of the dielectric substrate greater than 0.9. Drive

[0101] For illustrative purposes, in the context of the present invention, the reader is a transmitter-receiver reader of electromagnetic waves; the operating principle of said reader is based on the emission of an electromagnetic signal towards the identification device (for example the label) which will reflect said signal according to its geometry (and for example its own resonance characteristics) and on the capture by the reader of said reflected signal - thus, the processing of the received signal (in particular through a decoding step) will make it possible to retrieve the information contained in the device (for example, the label / the tag).

[0102] Thus, in general, the chipless radio frequency identification devices according to the present invention are part of an RFID system that also includes one or more RFID readers, which may or may not be connected to supervisory computers or an electronic board that performs processing, which can, for example, link to existing databases. These readers therefore allow the identification of objects thanks to the RFID tags affixed to them, said chipless RFID tags being comparable to a static radar target with a specific electromagnetic signature. Thus, in a particular embodiment of the present invention, the chipless RFID readers are therefore comparable to a radar in terms of operation, for example, an airborne radar detecting the signature of aircraft, with a difference in scale and power.For example, RFID tags without chips can be viewed as radar targets possessing a specific temporal or frequency signature. Any type of radar suitable for receiving / identifying the signal back-transmitted by the RFID tag can advantageously be used within the scope of the invention; by way of example and without limitation, we will mention pulse radar.

[0103] The coding capacities obtained by means of the chipless radio frequency identification devices according to the present invention meet the standards in force because the labels obtained allow for at least 40 bits of information, which corresponds to the EAN13 type barcodes. By way of illustration, values ​​of more than 40 bits for a credit card format [i.e. 40 / (85.60 × 53.98 mm) = 40 / 46 bits / cm2< ] have been obtained; thus, in a particular embodiment according to the present invention, the claimed devices are characterized by a coding capacity value greater than 0.85 bits / cm2< , for example greater than 1 bit / cm2< , greater than 2 bits / cm2< , or even greater than 5 bits / cm2< .

[0104] In one embodiment of the present invention, the claimed tag can be affixed to any type of object and / or living being (for example, an animal or a human). In another embodiment of the present invention, the object on which the tag will be affixed (preferably glued) can be selected from a large number of materials, including, but not limited to, metal, paper, fabric, plastic, for example, methacrylic copolymer resin, polyester, polycarbonate, polyethylene, polypropylene, and / or polyvinyl chloride, or even cellulosic-type materials such as, for example, wood, plywood, or crystalline materials such as glass or ceramics, for example, complex materials comprising one or more of these components, such as milk cartons.

[0105] In one embodiment of the present invention and provided that the dielectric substrate of the claimed tag meets the requirements of one or more of claims 1 to 13, said dielectric substrate may be selected from a large number of materials, including by way of non-limiting examples paper, fabric, plastic, for example a methacrylic copolymer resin, polyester, polycarbonate, polyethylene, polypropylene, and / or polyvinyl chloride, or even cellulosic-type materials such as, for example, wood, plywood or crystalline materials such as glass or ceramics, for example complex materials comprising one or more of these components such as milk cartons.

[0106] This application describes various technical features and advantages with reference to the Figures and / or various embodiments. Those skilled in the art will understand that the technical features of a given embodiment can in fact be combined with features of another embodiment unless the contrary is explicitly stated, or it is obvious that such features are incompatible, or that the combination does not provide a solution to at least one of the technical problems mentioned in this application. Furthermore, the technical features described in a given embodiment can be isolated from the other features of that embodiment unless the contrary is explicitly stated.

[0107] It should be obvious to those skilled in the art that the present invention allows for embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered illustrative, but may be modified within the scope defined by the attached claims, and the invention should not be limited to the details given above. Example

[0108] Packaging material - characteristics: Polymer film with a thickness of 1 mm. Apparent density: 60 kg / m³. Measured relative permittivity: 1.036 at 3.21 GHz and 1.035 at 3.89 GHz. Measured loss tangent: 1.9 x 10⁻⁵ at 3.21 GHz and 3.7 x 10⁻⁵ at 3.89 GHz.

[0109] Using a commercially available packaging material as a dielectric substrate and having the characteristics indicated above, tags with a ground plane were produced with the following characteristics: A 10-micron-thick aluminum layer covers the entire surface of the substrate; conductive patterns similar to those of the figure 1 , made of aluminum and 10 microns thick.

[0110] These tags are characterized by different identifiers and superior quality factors.

[0111] In a particular embodiment according to the present invention, the chipless RFID tag will be successively constituted of an optional but preferred conductive layer with a thickness between 200 nm and 20 microns, for example less than 10 microns, or even less than 2 microns, surmounted by an optional but preferred dielectric film with a thickness between 5 microns and 100 microns, surmounted by the main dielectric substrate (for example solid foam, foam board, corrugated board, honeycomb board and / or fabric, preferably solid foam) with a thickness between 0.5 mm and 3 mm, surmounted by a dielectric film with a thickness between 5 microns and 100 microns on which is / are affixed the pattern(s) consisting of a layer of conductive material with a thickness between 200 nm and 20 microns, for example less than 10 microns, or even less than 2 microns.

[0112] This RFID tag is also advantageously characterized by the width and length dimensions of all its layers (except for the conductive patterns, of course) being close to those of a credit or bank card; for example, these dimensions will preferably be between 86 mm ± 2 mm for the length and 54 ± 2 mm for the width (the more precise dimensions preferred being 85.725 × 53.975 mm).

Claims

1. Chipless RFID tag comprising a dielectric substrate on which a pattern or patterns are mounted consisting of a layer of conductive material, the dielectric substrate having a relative permittivity measured at any frequency between 3 and 10 GHz of between 1 and 2 and being characterised by a loss tangent value measured at any frequency between 3 and 10 GHz of less than 10-3.

2. Chipless RFID tag according to claim 1 characterised in that the dielectric substrate has a relative permittivity between 1.001 and 1.25.

3. Chipless RFID tag according to any one of the preceding claims characterised in that the loss tangent value is less than 2.10-4.

4. Chipless RFID tag according to any one of the preceding claims characterised in that the bulk density of the dielectric substrate is less than 250 kg.m-3, preferably less than 100 kg.m-3.

5. Chipless RFID tag according to any one of the preceding claims characterised in that the dielectric substrate is composed of a main dielectric substrate on which a dielectric film is mounted, for example a sheet of paper, cardboard or plastic, on which are placed the pattern or patterns composed of a layer of conductive material.

6. Chipless RFID tag according to claim 5 characterised in that the dielectric film is characterised by one, two or more of the following characteristics: - a relative permittivity measured at any frequency between 3 and 10 GHz greater than that of the main dielectric substrate, preferably a relative permittivity greater than 1.25, for example greater than 2, preferably a relative permittivity less than 3.5, and / or - a loss tangent value measured at any frequency between 3 and 10 GHz greater than that of the main dielectric substrate, preferably a loss tangent value less than 2.10-2, and / or - a thickness at least ten times less than that of the main dielectric substrate, preferably a thickness of less than 100 microns, for example less than 50 microns; and / or - composed of plastic material, for example polyethylene, polypropylene or polyethylene terephthalate.

7. Chipless RFID tag according to any one of the preceding claims characterised in that the upper part of the dielectric substrate is in contact with the pattern or patterns consisting of a layer of conductive material.

8. Chipless RFID tag according to any one of the preceding claims characterised in that the thickness of the dielectric substrate is greater than 0.5 mm, for example greater than 0.75 mm.

9. Chipless RFID tag according to any one of the preceding claims characterised in that the thickness of the dielectric substrate is less than 3 mm, for example less than 1.5 mm.

10. Chipless RFID tag according to any one of the preceding claims characterised in that the conductive layer constituting the pattern has a conductive material thickness greater than 200 nm and less than 20 microns.

11. Chipless RFID tag according to any one of the preceding claims characterised in that the conductive layer constituting the pattern has a conductive material thickness greater than 400 nm and less than 2 microns.

12. Chipless RFID tag with ground plane according to any one of the preceding claims characterised in that it comprises a layer of conductive material under the dielectric substrate, preferably under the entire surface of the dielectric substrate.

13. Chipless RFID tag according to claim 12 characterised in that the layer of conductive material under the dielectric substrate has a conductive material thickness greater than 200 nm and less than 20 microns.

14. Chipless RFID tag according to any one of the claims 12 and 13 characterised in that the layer of conductive material under the dielectric substrate has a conductive material thickness greater than 400 nm and less than 2 microns.

15. Chipless RFID tag according to any one of the preceding claims characterised in that the dielectric substrate is selected from dielectric substrates made from solid foam, foam board, corrugated cardboard, cellular cardboard or fabric.

16. Chipless RFID tag according to claim 15 characterised in that the dielectric substrate is a solid polymer foam.

17. Chipless RFID tag according to claim 16 characterised in that the dielectric substrate is a solid polymer foam having a bubble density of between 104 and 109 bubbles / cm3.

18. Chipless RFID tag according to any one of the preceding claims characterised in that the dielectric substrate is a solid polymer foam having a bubble size the average diameter of which is between 20 microns and 200 microns.

19. Chipless RFID tag according to any one of the preceding claims characterised in that ratio between the total upper surface of the dielectric substrate and the upper surface of the dielectric substrate covered with the pattern(s) consisting of a layer of conductive material, is greater than 2.

20. Chipless RFID tag with a ground plane according to any one of the claims 12 to 19 characterised in that the ratio between the lower surface of the dielectric substrate covered with the layer of conductive material and the total lower surface of the dielectric substrate, is greater than 0.9.

21. Chipless RFID tag according to any one of the claims 5 to 20 characterised in that it is successively constituted: - of a conductive layer, - on which a dielectric film is mounted, - on which the main dielectric substrate is mounted (for example solid foam, foam board, corrugated cardboard, cellular cardboard and / or fabric, preferably solid foam) - on which a dielectric film is mounted on which the pattern or patterns composed of a layer of conductive material are placed.

22. Chipless RFID tag according to claim 21 characterised in that - the conductive layer has a thickness of between 200 nm and 20 microns, for example less than 10 microns, or even less than 2 microns, - on the conductive layer is mounted a dielectric film the thickness of which is between 5 microns and 100 microns, - on the dielectric film is mounted the main dielectric substrate (for example solid foam, foam board, corrugated cardboard, cellular cardboard and / or fabric, preferably solid foam) the thickness of which is between 0.5 mm and 3 mm, - on the main dielectric substrate is mounted a dielectric film the thickness of which is between 5 microns and 100 microns and on which the pattern or patterns composed of a layer of conductive material are placed the thickness of which is between 200 nm and 20 microns, for example less than 10 microns, or even less than 2 microns.

23. Manufacturing process of a chipless RFID tag according to any one of the claims 5 to 22 by wrapping or welding at the extremity of the layers making up the tag so as to keep them in contact without glueing them.