Magnetically-controllable sound wave radio frequency identification tag

Abstract

The invention provides a magnetically controllable sound wave radio frequency identification tag, which belongs to the technical field of wireless radio frequency identification, and is characterized in that a sound wave transmission channel is formed on the surface of a piezoelectric substrate; the interdigital transducer is arranged on the surface of the piezoelectric substrate; the reflecting gratings are arranged on the surface of the piezoelectric substrate, and the reflecting gratings and the interdigital transducers are arranged at intervals; and the at least one magnetic film is arranged on the surface of the piezoelectric substrate between the reflecting gratings and the interdigital transducers, is arranged with the interdigital transducers and the plurality of reflecting gratings at intervals, and is used for absorbing the energy of sound waves through ferromagnetic resonance and dynamically regulating and controlling the code of the tag. The magnetic film is introduced on the basis of a traditional sound wave radio frequency identification tag, due to the ferromagnetic resonance effect, sound waves passing through the magnetic film can be absorbed, and the absorption degree of the magnetic film to sound wave energy can be controlled by an external magnetic field.

Description

Technical Field

[0001] The invention relates to the technical field of wireless radio frequency identification, and in particular to a magnetically controllable acoustic wave radio frequency identification tag. Background Art

[0002] Radio frequency identification is a method of identifying a target through contactless data communication between a reader and an identification tag. It can be used in fields such as identity recognition, anti-counterfeiting, information statistics, and security control. The acoustic wave device composed of an interdigital transducer has wireless passive characteristics and is widely used in the field of wireless radio frequency identification. The acoustic wave radio frequency identification tag obtains energy through an induced current and excites the acoustic wave. The acoustic wave energy is converted into an electrical signal by the interdigital transducer, and then a decodable electromagnetic wave signal is sent out. The electromagnetic wave signal is decoded to obtain digital information composed of "0" and "1", that is, the code of the identification tag. At present, the coding information contained in the acoustic wave radio frequency identification tag is directly related to the physical structure of the device. After an acoustic wave radio frequency identification tag is prepared, the coding information will not be adjustable. In practical applications, when the current code needs to be changed, the entire identification tag needs to be replaced. Therefore, traditional acoustic wave radio frequency identification tags cannot be used as dynamic tags. The process of replacing tags is cumbersome and prone to errors.

[0003] Therefore, in view of the above situation, it is necessary to provide a magnetically controllable acoustic wave radio frequency identification tag, which can dynamically adjust the encoding of the identification tag without changing the physical structure of the identification tag, so that the content of the identification tag can be dynamically adjusted, eliminating the need to replace the label when changing the encoding. Summary of the invention

[0004] In view of this, the present invention proposes a method of introducing a magnetic film on the basis of a traditional acoustic wave radio frequency identification tag, wherein the ferromagnetic resonance selectively absorbs the acoustic wave energy passing through the magnetic film, and a magnetically controllable acoustic wave radio frequency identification tag can be realized without replacing the acoustic wave radio frequency identification tag.

[0005] The present invention provides a magnetically controllable acoustic wave radio frequency identification tag, comprising: A piezoelectric substrate, with a sound wave transmission channel formed on the surface; An interdigital transducer is arranged on the surface of the piezoelectric substrate; A plurality of reflection gratings are arranged on the surface of the piezoelectric substrate and are spaced apart from the interdigital transducers; At least one magnetic film is arranged on the surface of the piezoelectric substrate (01) between the reflection grating and the interdigital transducer, and is spaced apart from the interdigital transducer and the plurality of reflection gratings, and is used to absorb the energy of the sound wave through ferromagnetic resonance, and dynamically regulate the coding of the tag.

[0006] On the basis of the above technical solution, preferably, the interdigital transducer includes a plurality of first metal electrodes, a second metal electrode, a first bus bar and a second bus bar, the plurality of first metal electrodes and the plurality of second metal electrodes are extended in parallel along the length direction of the piezoelectric substrate, and the plurality of first metal electrodes and the plurality of second metal electrodes are staggered and spaced apart; the ends of the plurality of first metal electrodes are electrically connected to the first bus bar, the ends of the plurality of second metal electrodes are electrically connected to the second bus bar, the plurality of first metal electrodes serve as signal ports, and the plurality of second metal electrodes are grounded through the second bus bar.

[0007] Preferably, the number of the first metal electrodes is equal to the number of the second metal electrodes; and the distance between adjacent first metal electrodes and adjacent second metal electrodes is consistent.

[0008] Preferably, the plurality of reflective grids each include a plurality of third metal electrodes and a third bus bar, the plurality of third metal electrodes are arranged in parallel and at intervals along the extension direction of the piezoelectric substrate, the two ends of the plurality of third metal electrodes in the extension direction are electrically connected to the third bus bar respectively, and the spacing between adjacent third metal electrodes is equal; the third metal electrode is arranged in parallel with the first metal electrode or the second metal electrode.

[0009] Further preferably, the propagation direction of the acoustic wave in the piezoelectric substrate is perpendicular to the length direction of the first metal electrode, the second metal electrode or the third metal electrode.

[0010] Further preferably, the plurality of reflection gratings are arranged on the same side direction or both sides of the length extension direction of the IDT, and the spacings between the reflection gratings and the IDT are unequal.

[0011] Based on the above technical solution, preferably, at least one magnetic film is arranged opposite to the third metal electrode of the reflective grid, and the dimension of at least one magnetic film extending along the width direction of the piezoelectric substrate is adapted to the length of the third metal electrode.

[0012] Preferably, the material of at least one magnetic film is any one of Ni, FeGa, CoFeB, FeGaB, Co or FeCoSiB.

[0013] Further preferably, when the number of the magnetic films exceeds one, the sizes and materials of different magnetic films extending along the length direction of the piezoelectric substrate are not completely the same.

[0014] On the basis of the above technical solution, preferably, the material of the piezoelectric substrate is any one of 128°YX-LiNbO3, LiTaO3, AlN or quartz.

[0015] The magnetically controllable acoustic wave radio frequency identification tag provided by the present invention has the following beneficial effects compared with the prior art: This solution chooses to configure a magnetic film between the interdigital transducer and the reflective grating. By utilizing the ferromagnetic resonance effect, the sound waves passing through the magnetic film will be absorbed. The degree of absorption of the sound wave energy by the magnetic film can be controlled by the external magnetic field, thereby allowing the encoding of the identification tag to be dynamically controlled through the magnetic field, overcoming the deficiency that conventional acoustic wave radio frequency identification tags cannot be used dynamically. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 2 This is a schematic structural diagram of Example 1 of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 3 The relationship between the resonant magnetic field and the frequency of the magnetic film made of Ni material in Example 1 of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 4 It is a schematic diagram of the dynamic control effect of the magnetic film of Example 1 of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 5 This is a schematic structural diagram of a second embodiment of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 6 The relationship between the resonant magnetic field and the frequency of the magnetic film made of CoFeB material in Example 2 of a magnetically controllable acoustic wave radio frequency identification tag of the present invention; Figure 7 It is a schematic diagram of the dynamic control effect of the magnetic film of Example 2 of a magnetically controllable acoustic wave radio frequency identification tag of the present invention.

[0018] Figure numerals: 01, piezoelectric substrate; 02, first metal electrode; 03, second metal electrode; 04, first magnetic film; 05, first reflection grating; 06, second reflection grating; 07, second magnetic film. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] After an acoustic RFID tag is produced, the coding information cannot be adjusted. In practical applications, when the current coding needs to be changed, the entire identification tag needs to be replaced. Figure 1 As shown, the present invention provides a magnetically controllable acoustic wave radio frequency identification tag, comprising: Piezoelectric substrate 01, the surface of the piezoelectric substrate forms an acoustic wave transmission channel; Figure 1 The horizontal direction is the length extension direction of the piezoelectric substrate, and the direction perpendicular to the horizontal direction is the width direction of the piezoelectric substrate. In the present application, the material of the piezoelectric substrate 01 can be any one of 128°YX-LiNbO3, LiTaO3, AlN or quartz, but the piezoelectric substrate 01 is not limited to the materials listed above, as long as it is a material with piezoelectric properties.

[0021] The IDT is arranged on the surface of the piezoelectric substrate 01; as the name implies, the IDT is a pair of metal electrodes shaped like two interlaced fingers formed on the piezoelectric substrate 01. External signals are loaded on the IDT to realize the mutual conversion between electrical signals and acoustic signals. Figure 1 There is only one interdigital transducer in the device, so it serves as both an input transducer and an output transducer.

[0022] A plurality of reflection gratings are arranged on the surface of the piezoelectric substrate 01 and are spaced apart from the interdigital transducers; after the sound waves emitted by the interdigital transducers are reflected by the reflection gratings, they return to the interdigital transducers for outputting electrical signals. The number of reflection gratings can be increased or decreased as needed. A plurality of reflection gratings are arranged on the same side or both sides of the direction in which the length of the interdigital transducers extends, and the spacings between the reflection gratings and the interdigital transducers are not equal to each other. Figure 1 The two reflection gratings are located at the same side of the IDT. In addition to this situation, more than two reflection gratings can also be located at both sides of the IDT.

[0023] At least one magnetic film is arranged on the surface of the piezoelectric substrate 01 between the reflection grid and the interdigital transducer, and is spaced apart from the interdigital transducer and a number of reflection grids, and is used to absorb the energy of the sound wave through ferromagnetic resonance, and dynamically control the coding of the tag. The magnetic film absorbs the energy of the sound wave through ferromagnetic resonance, and the resonance frequency of magnetic film devices of different materials is also different. Under different external magnetic field conditions, the magnetic film works selectively, absorbing or not absorbing the energy of the sound wave, so that the electrical signal output by the interdigital transducer has different states, so that a single sound wave radio frequency identification tag has the ability to output multiple states.

[0024] like Figure 1 As shown, the interdigital transducer includes a plurality of first metal electrodes 02, a second metal electrode 03, a first bus bar and a second bus bar. The plurality of first metal electrodes 02 and the plurality of second metal electrodes 03 are arranged in parallel and extend along the length direction of the piezoelectric substrate 01, and the plurality of first metal electrodes 02 and the plurality of second metal electrodes 03 are arranged in an interlaced and spaced manner; the ends of the plurality of first metal electrodes 02 are electrically connected to the first bus bar, the ends of the plurality of second metal electrodes 03 are electrically connected to the second bus bar, the plurality of first metal electrodes 02 serve as signal ports, and the plurality of second metal electrodes 03 are grounded through the second bus bar. The first bus bar is arranged vertically and electrically connected to each first metal electrode 02, and the second bus bar is arranged vertically and electrically connected to each second metal electrode 03.

[0025] like Figure 1 As shown, the number of the first metal electrodes 02 and the number of the second metal electrodes 03 are equal; the distance between adjacent first metal electrodes 02 and adjacent second metal electrodes 03 is kept consistent.

[0026] Figure 1 There are two different reflection grids, marked as the first reflection grid 05 and the second reflection grid 06; the reflection grids all include a plurality of third metal electrodes and a third bus bar, the plurality of third metal electrodes are arranged in parallel and at intervals along the extension direction of the piezoelectric substrate 01, the two ends of the extension direction of the plurality of third metal electrodes are respectively electrically connected to the third bus bar, and the spacing between adjacent third metal electrodes is equal; the third metal electrode is arranged in parallel with the first metal electrode 02 or the second metal electrode 03. The propagation direction of the acoustic wave in the piezoelectric substrate 01 is perpendicular to the length direction of the first metal electrode 02, the second metal electrode 03 or the third metal electrode. The length direction of each metal electrode is the width direction of the piezoelectric substrate 01.

[0027] In order to achieve specific sound wave absorption, it is necessary to ensure that the magnetic film is directly opposite to the reflection grid, that is, at least one magnetic film is directly opposite to the third metal electrode of the reflection grid, and the dimension of at least one magnetic film extending along the width direction of the piezoelectric substrate 01 is adapted to the length of the third metal electrode.

[0028] The magnetic film is usually made of a magnetic material with a relatively large magnetoelastic coefficient. The material of at least one magnetic film of the present invention is any one of Ni, FeGa, CoFeB, FeGaB, Co or FeCoSiB, but the present invention is not limited to these materials. Any magnetic material that can be used to prepare a magnetic film is acceptable. If it is necessary to selectively absorb acoustic signals of different frequencies, when more than one magnetic film is used, the dimensions and materials of different magnetic films extending along the length direction of the piezoelectric substrate 01 are not completely the same.

[0029] The layout mode and the state of absorbing the energy of sound waves of the present invention are described below in conjunction with specific embodiments.

[0030] Example 1: Reference Figure 2 , Figure 3 and Figure 4 In this embodiment, an interdigital transducer is prepared on the surface of a piezoelectric substrate 01 made of 128°YX-LiNbO3. The interdigital transducer includes a first metal electrode 02, a second metal electrode 03, a first bus bar and a second bus bar. The first metal electrode 02 and the second metal electrode 03 are arranged in parallel, staggered and spaced. In this embodiment, the first metal electrode 02 and the first bus bar are used as signal ports, and the second metal electrode 03 and the second bus bar are grounded. The materials used for the electrodes of the interdigital transducer and the reflector are both metal aluminum.

[0031] A first reflection grid 05 and a second reflection grid 06 are respectively arranged on both sides of the IDT, and both the first reflection grid 05 and the second reflection grid 06 include a third metal electrode and a third bus bar. The third metal electrodes are arranged in parallel and at intervals. Figure 2 The length of the third metal electrode in the embodiment does not exceed the length of the first metal electrode 02 and the second metal electrode 03. Figure 2 It can be seen that the width of the first metal electrode 02, the width of the second metal electrode 03, the width of the third metal electrode, the spacing between adjacent first metal electrodes 02 and second metal electrodes 03, and the spacing between adjacent third metal electrodes are all p = 500nm. It should be noted that the shapes and quantities of the first metal electrode, the second metal electrode, the third metal electrode and the first bus bar, the second bus bar, and the third bus bar in each of the drawings are only for illustration and are not necessarily constrained by the example in the drawings.

[0032] A first magnetic film 04 is disposed on the surface of the piezoelectric substrate 01 between the IDT and the second reflective grating 06; the distance between the IDT and the first reflective grating 05 is d1, and the distance between the IDT and the second reflective grating 06 is d2. The dimension of the first magnetic film 04 along the length direction of the piezoelectric substrate 01 is W. mIn this embodiment, the spacing d1 is 200 μm, the spacing d2 is 300 μm, and the width W m is 50 μm, and it can be seen that there are gaps between the first magnetic film 04, the interdigital transducer, and the second reflective grating 06. The material of the first magnetic film 04 is Ni. Figure 3 is the relationship between the resonant magnetic field and the frequency of the first magnetic film 04. The acoustic wave in the piezoelectric substrate 01 is a 2 GHz Rayleigh wave, and the propagation direction of the acoustic wave is perpendicular to the length direction of each metal electrode. Figure 3 It can be seen that at a sound wave frequency of 2 GHz, the magnitude of the ferromagnetic resonance magnetic field of the first magnetic film 04 is 10 mT. Specifically, when the magnetic film is in an external magnetic field and the direction of the magnetic field is at a 45° angle to the direction of sound wave propagation, the external magnetic field is allowed to regulate the energy of the sound wave.

[0033] The specific process of regulating the energy of the sound wave is as follows: under the action of a 10mT magnetic field, the magnetic moment of the material Ni of the magnetic film is arranged parallel to the direction of the external magnetic field. When the sound wave propagates to the magnetic film area, the magnetoelastic energy generated by the sound wave drives the precession of the magnetic moment, that is, stimulates ferromagnetic resonance in the magnetic film. In the ferromagnetic resonance, the precession of the magnetic moment will absorb the energy of the sound wave, causing the energy of the sound wave to weaken after passing through the magnetic film. When the magnetic field size is far away from 10mT, it is difficult for the sound wave to stimulate the ferromagnetic resonance, so the energy change of the sound wave after passing through the magnetic film can be ignored.

[0034] like Figure 4 The figure shows the response changes obtained at the signal port of the interdigital transducer. When the magnetic field is 100mT, the material Ni of the magnetic film hardly absorbs the acoustic wave energy. According to the acoustic wave energy, the device code is identified as "11"; when the magnetic field is 10mT, the material Ni of the magnetic film absorbs the acoustic wave energy. According to the acoustic wave energy, the device code is identified as "10". In this way, under different external magnetic fields, the same acoustic wave RFID tag has two different output states, so there is no need to replace the acoustic wave RFID tag.

[0035] Example 2: Reference Figure 5 , Figure 6 and Figure 7 , an interdigital transducer is prepared on the surface of a piezoelectric substrate 01 made of 128°YX-LiNbO3. The interdigital transducer includes a first metal electrode 02, a second metal electrode 03, a first bus bar and a second bus bar. The first metal electrode 02 and the second metal electrode 03 are arranged in parallel, staggered and spaced. In this embodiment, the first metal electrode 02 and the first bus bar are used as signal ports, and the second metal electrode 03 and the second bus bar are grounded. The materials used for the electrodes of the interdigital transducer and the reflector are both metal aluminum. It can be seen that the structural content of this part is exactly the same as that of Example 1.

[0036] The difference is that two different reflection grids are configured on the same side of the interdigital transducer: a first reflection grid 05 and a second reflection grid 06; and two different magnetic films are configured accordingly: a first magnetic film 04 and a second magnetic film 07. In this embodiment, the first reflection grid 05 and the second reflection grid 06 both include a third metal electrode and a third bus bar. The third metal electrodes are spaced and arranged in parallel. Figure 5 The shapes and quantities of the first metal electrode 02 , the second metal electrode 03 , the third metal electrode, the first bus bar, the second bus bar and the third bus bar shown in the figure are not considered as limitations on the scheme, and the quantity and shape of each component can be changed arbitrarily.

[0037] Figure 5 The length of the third metal electrode in the embodiment does not exceed the length of the first metal electrode 02 and the second metal electrode 03. Figure 5 It can be seen that the width of the first metal electrode 02, the width of the second metal electrode 03, the width of the third metal electrode, the spacing between adjacent first metal electrodes 02 and second metal electrodes 03, and the spacing between adjacent third metal electrodes are all p=200nm. The material of the first magnetic film 04 is Ni, and the material of the second magnetic film 07 is CoFeB. The relationship between the resonant magnetic field and the frequency of the first magnetic film 04 and the second magnetic film 07 is respectively referred to Figure 3 and Figure 6 .

[0038] The distance between the IDT and the first reflective grating 05 is d1, and the distance between the IDT and the second reflective grating 06 is d2. The dimension of the first magnetic film 04 along the length direction of the piezoelectric substrate 01 is W. m1 The size of the second magnetic film 07 along the length direction of the piezoelectric substrate 01 is W m2 In this embodiment, the spacing d1 is 20 μm, the spacing d2 is 40 μm, and the width W m1 10μm, width W m2 The acoustic wave in the piezoelectric substrate is a 5GHz Rayleigh wave, and the direction of acoustic wave propagation is perpendicular to the length direction of the metal electrode. Figure 3 The relationship between the resonant magnetic field and frequency of the material Ni of the first magnetic film is obtained, and the ferromagnetic resonant magnetic field of the first magnetic film Ni is 50mT at a frequency of 5GHz. Figure 6 The relationship between the resonant magnetic field and frequency of the material CoFeB of the second magnetic film is obtained, and the ferromagnetic resonant magnetic field of the material CoFeB of the second magnetic film is 20mT at a frequency of 5GHz. When the two magnetic films are in an external magnetic field, and the direction of the magnetic field is at a 45° angle to the propagation direction of the sound wave, the external magnetic field is allowed to regulate the energy of the sound wave.

[0039] The specific process of regulating the energy of the sound wave is as follows: under the action of a 50mT magnetic field, the ferromagnetic resonance of the first magnetic film 04 causes the energy of the sound wave to be absorbed, while the ferromagnetic resonance of the second magnetic film 07 can be ignored, and the energy of the sound wave passing through the second magnetic film 07 remains unchanged. Under the action of a 20mT magnetic field, the ferromagnetic resonance of the second magnetic film 07 causes the energy of the sound wave to be absorbed, while the ferromagnetic resonance of the first magnetic film 04 can be ignored, and the energy of the sound wave passing through the first magnetic film 04 remains unchanged. When the magnetic field is far away from 20mT and 50mT, the ferromagnetic resonance in the first magnetic film 04 and the second magnetic film 07 can be ignored, so the energy of the sound wave passing through the first magnetic film 04 and the second magnetic film 07 remains unchanged.

[0040] The response of the device is obtained from the signal port of the interdigital transducer. Figure 7 When the magnetic field is 100mT, the device code is identified as "11" according to the acoustic wave energy; when the magnetic field is 50mT, the device code is identified as "01" according to the acoustic wave energy; when the magnetic field is 20mT, the device code is identified as "10" according to the acoustic wave energy. In this way, by configuring two different magnetic films, the same acoustic wave RFID tag can achieve three states of output.

[0041] It should be noted that the materials of the first magnetic film 04 and the second magnetic film 07 selected above can be arbitrarily replaced from the magnetic materials used to prepare the magnetic films, as long as the resonant magnetic fields of the two are different.

[0042] According to the different resonance matching of the set magnetic film, the combined output state can be further expanded, and the same acoustic radio frequency identification tag can achieve more diverse state outputs, eliminating the inconvenience of changing tags.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetically controllable acoustic wave radio frequency identification tag, characterized in that: include: A piezoelectric substrate, with a sound wave transmission channel formed on the surface; An interdigital transducer is arranged on the surface of the piezoelectric substrate; A plurality of reflection gratings are arranged on the surface of the piezoelectric substrate and are spaced apart from the interdigital transducers; At least one magnetic film is arranged on the surface of the piezoelectric substrate between the reflection grating and the IDT, and is spaced apart from the IDT and a plurality of reflection gratings, for absorbing the energy of the sound wave through ferromagnetic resonance and dynamically regulating the coding of the tag.

2. The magnetically controllable acoustic wave radio frequency identification tag according to claim 1, characterized in that: The interdigital transducer includes a plurality of first metal electrodes, a second metal electrode, a first bus bar and a second bus bar. The plurality of first metal electrodes and the plurality of second metal electrodes are arranged to extend in parallel along the length direction of the piezoelectric substrate, and the plurality of first metal electrodes and the plurality of second metal electrodes are arranged in a staggered and spaced manner; the ends of the plurality of first metal electrodes are electrically connected to the first bus bar, the ends of the plurality of second metal electrodes are electrically connected to the second bus bar, the plurality of first metal electrodes serve as signal ports, and the plurality of second metal electrodes are grounded through the second bus bar.

3. The magnetically controllable acoustic wave radio frequency identification tag according to claim 2, characterized in that: The number of the first metal electrodes and the second metal electrodes is equal; the distance between adjacent first metal electrodes and adjacent second metal electrodes is consistent.

4. The magnetically controllable acoustic wave radio frequency identification tag according to claim 2, characterized in that: The plurality of reflection grids each include a plurality of third metal electrodes and a third bus bar. The plurality of third metal electrodes are arranged in parallel and at intervals along the extension direction of the piezoelectric substrate. Both ends of the plurality of third metal electrodes in the extension direction are electrically connected to the third bus bar respectively, and the spacing between adjacent third metal electrodes is equal. The third metal electrodes are arranged in parallel with the first metal electrode or the second metal electrode.

5. The magnetically controllable acoustic wave radio frequency identification tag according to claim 4, characterized in that: The propagation direction of the acoustic wave in the piezoelectric substrate is perpendicular to the length direction of the first metal electrode, the second metal electrode or the third metal electrode.

6. The magnetically controllable acoustic wave radio frequency identification tag according to claim 4, characterized in that: The plurality of reflection gratings are arranged on the same side or both sides of the length extension direction of the IDT, and the spacings between the reflection gratings and the IDT are unequal.

7. The magnetically controllable acoustic wave radio frequency identification tag according to claim 1, characterized in that: At least one magnetic film is arranged opposite to the third metal electrode of the reflective grid, and the dimension of the at least one magnetic film extending along the width direction of the piezoelectric substrate is adapted to the length of the third metal electrode.

8. The magnetically controllable acoustic wave radio frequency identification tag according to claim 7, characterized in that: The material of at least one magnetic thin film is any one of Ni, FeGa, CoFeB, FeGaB, Co or FeCoSiB.

9. The magnetically controllable acoustic wave radio frequency identification tag according to claim 8, characterized in that: When the number of the magnetic thin films exceeds one, the sizes and materials of the different magnetic thin films extending along the length direction of the piezoelectric substrate are not completely the same.

10. The magnetically controllable acoustic wave radio frequency identification tag according to claim 1, characterized in that: The material of the piezoelectric substrate is any one of 128°YX-LiNbO3, LiTaO3, AlN or quartz.

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