Miniaturized tunable RFID tag antenna with embedded interdigital structure

Abstract

The utility model provides a miniaturized tunable ultrahigh frequency RFID tag antenna with an embedded interdigital structure. The miniaturized tunable ultrahigh frequency RFID tag antenna is composed of a tag chip (6), a top metal radiation unit and a bottom dielectric substrate (7). The top radiation unit comprises a rectangular ring (1), a first L-shaped gradually-changing bending arm (2), a second L-shaped gradually-changing bending arm (3), a first interdigital center metal belt (4) and a second interdigital center metal belt (5). The rectangular ring (1), the L-shaped gradually-changed bending arm and the interdigital central metal belt are all located above the dielectric substrate (7); the rectangular ring is located in the center of the top metal radiation unit; the L-shaped gradually-changed bending arms are located on the left side and the right side of the rectangular ring. The tag chip is located on a horizontal strip on one side of the rectangular ring; the interdigital center metal belt is located in a center gap formed by mirror symmetry of the left part and the right part of the L-shaped gradually-changed bent arm. The tunable laser has the advantages of being small in overall size, simple in structure and tunable, and is suitable for being applied to the surfaces of objects of various shapes and sizes.

Description

Technical Field

[0001] The utility model relates to the technical field of wireless communication, in particular to a miniaturized tunable RFID tag antenna embedded with an interdigital structure. Background Art

[0002] Radio Frequency Identification (RFID) is a contactless automatic identification communication technology that is widely used in manufacturing, logistics, medical and other fields with its advantages of fast reading and writing speed, large data capacity, and long reading and writing distance. The working process of the RFID system is as follows: the reader sends a radio frequency signal of a certain frequency through the antenna, the electronic tag is stimulated to generate an induced current and starts working when it obtains sufficient energy. The activated tag sends its own information through the built-in antenna, the reader antenna receives the signal, demodulates and decodes the signal, and sends it to the computer system for corresponding processing.

[0003] In RFID applications, tag antennas are usually attached to the objects to be identified, and their shapes, sizes, surface materials, and application environments vary. Small-sized tag antennas can reduce processing costs and can be applied to more scenarios. Therefore, the design of miniaturized tag antennas has always been a challenge. People have done a lot of research, such as using dielectric substrates with high dielectric constants, loading lumped components, and using fractal technology. However, the use of substrates with high dielectric constants is not economical and not suitable for large-scale production; loading lumped components increases the difficulty of tag manufacturing; and using fractal technology complicates the design process. In addition, when the tag contacts an object with a large difference in dielectric constant, the resonant frequency and impedance characteristics of the tag antenna will be affected. For example, objects with high dielectric constants will cause the actual resonant frequency of the tag antenna to shift to a low frequency, and may even exceed the ultra-high frequency band of radio frequency identification, greatly limiting the scope and environment of radio frequency identification technology. Although a variety of miniaturized tag antennas have been developed, the performance of RFID tag antennas cannot currently meet the application requirements of special fields, such as a class of miniaturized, bendable, and tunable tag antennas.

[0004] The utility model proposes a miniaturized tunable RFID tag antenna embedded with an interdigital structure, with a -10dB band of 916MHz-924MHz in the ultra-high frequency radio frequency identification working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi. The communication frequency can be covered by the working frequency band of my country's RFID antenna, and has the advantages of small overall size, simple structure and tunability. It is suitable for application on the surface of objects of various shapes and sizes, especially in an environment where the volume of the marker is small and remote communication needs to be established. Utility Model Content

[0005] The utility model proposes a miniaturized tunable RFID tag antenna embedded with an interdigitated structure, which is a miniaturized tunable RFID tag antenna embedded with an interdigitated structure applied to the UHF frequency band. It has the advantages of small overall size, simple structure and tunability, and is suitable for application in an environment where the tag size requirement is small and remote communication needs to be established.

[0006] The utility model adopts the following technical solutions.

[0007] A miniaturized tunable RFID tag antenna embedded with an interdigital structure, the tag antenna being a single-sided structure including a radiation unit, an RFID tag chip, and a dielectric substrate; the radiation unit is located on the dielectric substrate (7); the radiation unit is provided with a rectangular ring (1), a first L-shaped gradually bent arm (2), and a second L-shaped gradually bent arm (3); the rectangular ring (1) is located at the upper part of the central axis area of ​​the radiation unit, and the RFID tag chip (6) is provided at a horizontal strip of the rectangular ring; the middle of the horizontal arm end of the first L-shaped gradually bent arm is connected to the horizontal first interdigital center metal strip (4), and the middle of the horizontal arm end of the second L-shaped gradually bent arm is connected to the horizontal second interdigital center metal strip (5);

[0008] The first L-shaped gradually bent arm (2) and the second L-shaped gradually bent arm (3) are located on one side of the rectangular ring and are connected to form a combination A. The radiation unit on the other side of the rectangular ring is provided with a combination B whose top view shape is a mirror image of the combination A. The middle parts of the ends of the two horizontal arms of the combination B are respectively connected to the two horizontal C-shaped arms. The first interdigitated central metal belt and the second interdigitated central metal belt are respectively inserted into the gaps of the two horizontal C-shaped arms and are respectively combined with the two horizontal C-shaped arms to form the first interdigitated metal belt and the second interdigitated metal belt located at the central axis of the radiation unit.

[0009] The rectangular ring (1) has a micro-notch etched in a horizontal strip on one side. The micro-notch is used to place a tag chip (6) and is connected to the rectangular ring (1). It is also used to achieve energy transmission between the tag antenna and the tag chip and adjust impedance matching between the two.

[0010] The end of the first L-shaped gradually bent arm (2) and the head of the second L-shaped gradually bent arm (3) are connected to form an L-shaped gradually bent arm structure, and the entire L-shaped gradually bent arm structure is then connected to the rectangular ring (1). The L-shaped gradually bent arm structure is used to adjust the resonant frequency of the tag antenna.

[0011] The line width, line spacing, vertical arm height and horizontal arm length of the first L-shaped gradually bent arm (2) and the second L-shaped gradually bent arm (3) can be set according to actual performance requirements, and the corresponding dimensional parameter values ​​can be the same or different.

[0012] The first interdigitated central metal strip (4) and the second interdigitated central metal strip (5) respectively form two pairs of interdigitated structures with two horizontal C-shaped arms, which are used to achieve miniaturization of the tag antenna and tuning of the tag antenna during simulation and after manufacturing.

[0013] The length and width of each of the first interdigitated metal strips and the second interdigitated central metal strips and the overall height of the two structures are set according to actual performance requirements, and the corresponding size parameter values ​​can be the same or different.

[0014] The rectangular ring (1), the first L-shaped gradually bent arm (2), the second L-shaped gradually bent arm (3), the first interdigitated central metal belt (4), the second interdigitated central metal belt (5), and the two horizontal C-shaped arms are all formed from aluminum.

[0015] The radiation unit is an etching structure on a dielectric substrate.

[0016] The substrate is a flexible polymer film.

[0017] The tag antenna has a -10dB frequency band of 916MHz-924MHz in the UHF RFID working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi.

[0018] The rectangular ring (1), the first L-shaped gradually bent arm (2), the second L-shaped gradually bent arm (3), the first interdigitated central metal belt (4), and the second interdigitated central metal belt (5) are all made of metal aluminum, and the antenna is etched on a dielectric substrate (7) using an etching process.

[0019] The dielectric substrate (7) is a flexible polymer film, the material of which includes polyimide or polyethylene terephthalate.

[0020] The tag antenna has a -10dB frequency band of 916MHz-924MHz in the UHF RFID working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi.

[0021] The tuning process of the tag antenna after manufacturing is as follows: first, the manufactured tag antenna is attached to the surface of the object to be tagged and the reading distance, sensitivity and other related tests are performed on it through a professional RFID tag performance measurement system. The actual resonant frequency of the tag antenna in the current state can be obtained according to the frequency response curve shown in the test results. If the actual resonant frequency is too low, the resonant frequency can be increased by reducing the metal area of ​​the first interdigital center metal belt (4) and the second interdigital center metal belt (5) by scraping with a knife; if the actual resonant frequency is too high, the resonant frequency can be reduced by increasing the metal area of ​​the first interdigital center metal belt (4) and the second interdigital center metal belt (5) by pasting metal foil.

[0022] Compared with the prior art, the utility model has the following advantages:

[0023] The utility model is a miniaturized tunable RFID tag antenna embedded with an interdigital structure for use in the UHF frequency band. The tag antenna comprises a metal radiation unit, an RFID tag chip and a dielectric substrate. The chip (6) is located on a horizontal strip on one side of a rectangular ring, and the metal radiation unit is located above the dielectric substrate (7). The metal radiation unit is composed of a rectangular ring (1), a first L-shaped gradient bending arm (2), a second L-shaped gradient bending arm (3), a first interdigital center metal strip (4), and a second interdigital center metal strip (5). The rectangular ring (1) can adjust the impedance matching between the antenna and the chip to achieve the purpose of conjugate matching between the tag chip and the antenna; by adjusting the size of the first L-shaped gradient bending arm (2) and the second L-shaped gradient bending arm (3), the resonant frequency of the tag antenna can be changed; by adjusting the size of the first interdigital center metal strip (4), the resonant frequency of the antenna can be fine-tuned; by adjusting the size of the second interdigital center metal strip (5), the resonant frequency of the antenna can be roughly adjusted.

[0024] After the tag antenna of the utility model is manufactured, it can be tuned by adjusting the relevant parameters of the two cross-finger center metal strips. The overall size of the antenna is 28mm×16mm×0.05mm. When the tag antenna is placed on the foam surface, the maximum transmission power is 99.9%, the maximum gain is -5.25dBi, and it has the function of full-process tunability.

[0025] The operating frequency of the utility model can be covered by the working frequency band of my country's RFID antenna. It has the advantages of small overall size, simple structure and tunability. It is suitable for application on the surface of objects of various shapes and sizes, especially in an environment where the volume of the marker is small and remote communication needs to be established. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0027] AttachedFigure 1 A three-dimensional diagram of an embodiment of the utility model;

[0028] Attached Figure 2 It is a schematic diagram of a top radiation unit composed of a rectangular ring, an L-shaped gradually bent arm and an interdigitated metal strip according to an embodiment of the utility model;

[0029] Attached Figure 3 This is a schematic diagram of the simulation results of the tag antenna reflection coefficient of an embodiment of the utility model;

[0030] Attached Figure 4 A schematic diagram of the power transmission coefficient of the tag antenna according to an embodiment of the utility model;

[0031] Attached Figure 5 The tag antenna gain XOY plane radiation pattern of the embodiment of the utility model;

[0032] Attached Figure 6 The tag antenna gain XOZ plane radiation pattern of the embodiment of the utility model;

[0033] In the figure, 1-rectangular ring; 2-first L-shaped gradually bent arm; 3-second L-shaped gradually bent arm; 4-first interdigitated central metal belt; 5-second interdigitated central metal belt; 6-RFID tag chip; 7-medium substrate;

[0034] 100- horizontal C-arm; 101- assembly A; 102- assembly B. DETAILED DESCRIPTION

[0035] As shown in the figure, a miniaturized tunable RFID tag antenna embedded with an interdigital structure is provided, wherein the tag antenna is a single-sided structure including a radiation unit, an RFID tag chip, and a dielectric substrate; the radiation unit is located on a dielectric substrate 7; the radiation unit is provided with a rectangular ring 1, a first L-shaped gradually bent arm 2, and a second L-shaped gradually bent arm 3; the rectangular ring 1 is located at the upper part of the central axis area of ​​the radiation unit, and an RFID tag chip 6 is provided at a horizontal strip of the rectangular ring; the middle of the horizontal arm end of the first L-shaped gradually bent arm is connected to the horizontal first interdigital center metal belt 4, and the middle of the horizontal arm end of the second L-shaped gradually bent arm is connected to the horizontal second interdigital center metal belt 5;

[0036] The first L-shaped gradually bent arm 2 and the second L-shaped gradually bent arm 3 are located on one side of the rectangular ring and are connected to form an assembly A101. The radiation unit on the other side of the rectangular ring is provided with an assembly B102 whose top view shape is a mirror image of the assembly A. The middle parts of the two horizontal arm ends of the assembly B are respectively connected to the two horizontal C-shaped arms 100, and the first interdigitated central metal belt and the second interdigitated central metal belt are respectively inserted into the notch gaps of the two horizontal C-shaped arms, and are respectively combined with the two horizontal C-shaped arms to form the first interdigitated metal belt and the second interdigitated metal belt located at the central axis of the radiation unit.

[0037] The rectangular ring 1 has a micro-notch etched in a horizontal strip on one side. The micro-notch is used to place the tag chip 6 and is connected to the rectangular ring 1. It is also used to realize energy transmission between the tag antenna and the tag chip and adjust the impedance matching between the two.

[0038] The end of the first L-shaped tapered bent arm 2 and the head of the second L-shaped tapered bent arm 3 are connected to form an L-shaped tapered bent arm structure, and the entire L-shaped tapered bent arm structure is then connected to the rectangular ring 1. The L-shaped tapered bent arm structure is used to adjust the resonant frequency of the tag antenna.

[0039] The line width, line spacing, vertical arm height, and horizontal arm length of the first L-shaped gradually bent arm 2 and the second L-shaped gradually bent arm 3 can be set according to actual performance requirements, and the corresponding size parameter values ​​can be the same or different.

[0040] The first interdigitated central metal band 4 and the second interdigitated central metal band 5 respectively form two pairs of interdigitated structures with two horizontal C-shaped arms, which are used to achieve miniaturization of the tag antenna and tuning of the tag antenna during simulation and after manufacturing.

[0041] The length and width of each of the first interdigitated metal strips and the second interdigitated central metal strips and the overall height of the two structures are set according to actual performance requirements, and the corresponding size parameter values ​​can be the same or different.

[0042] The rectangular ring 1, the first L-shaped gradually bent arm 2, the second L-shaped gradually bent arm 3, the first interdigitating central metal belt 4, the second interdigitating central metal belt 5, and the two horizontal C-shaped arms are all formed of aluminum.

[0043] The radiation unit is an etching structure on a dielectric substrate.

[0044] The substrate is a flexible polymer film.

[0045] The tag antenna has a -10dB frequency band of 916MHz-924MHz in the UHF RFID working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi.

[0046] The rectangular ring 1, the first L-shaped gradually bent arm 2, the second L-shaped gradually bent arm 3, the first interdigital center metal belt 4, the second interdigital center metal belt 5, and the two horizontal C-shaped arms 100 are all made of metal aluminum, and the antenna is etched on the dielectric substrate 7 using an etching process.

[0047] The dielectric substrate 7 is a flexible polymer film, and the material includes polyimide or polyethylene terephthalate.

[0048] The tag antenna has a -10dB frequency band of 916MHz-924MHz in the UHF RFID working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi.

[0049] The tuning process of the tag antenna after manufacturing is as follows: first, the manufactured tag antenna is attached to the surface of the object to be tagged and the reading distance, sensitivity and other related tests are performed on it through a professional RFID tag performance measurement system. The actual resonant frequency of the tag antenna in the current state can be obtained according to the frequency response curve shown in the test results. If the actual resonant frequency is too low, the resonant frequency can be increased by using a tool to scrape off and reduce part of the metal area on the first interdigital center metal belt 4 and the second interdigital center metal belt 5; if the actual resonant frequency is too high, the resonant frequency can be reduced by increasing the metal area on the first interdigital center metal belt 4 and the second interdigital center metal belt 5 by pasting metal foil.

[0050] Example:

[0051] In this example, a miniaturized tunable RFID tag antenna embedded with an interdigital structure is provided, wherein the tag antenna is a single-sided structure composed of a metal radiation unit, an RFID tag chip, and a dielectric substrate; wherein the metal radiation unit is provided with a rectangular ring (1), a first L-shaped gradually changing bent arm (2), a second L-shaped gradually changing bent arm (3), a first interdigital center metal belt (4), a second interdigital center metal belt (5), and a tag chip (6); the rectangular ring (1) is located in the middle upper part of the radiation unit, and the first L-shaped gradually changing bent arm (2) and the second L-shaped gradually changing bent arm (3) both comprise left and right parts that are mirror-symmetrical, and are respectively located on both sides of the rectangular ring (1) and are connected in sequence;

[0052] The first interdigitated metal belt and the second interdigitated metal belt are respectively located at the central gap formed by the mirror-symmetrical left and right parts of the first L-shaped gradual bending arm (2) and the second L-shaped gradual bending arm (3), and are respectively composed of the first interdigitated central metal belt (4), the second interdigitated central metal belt (5) and the two horizontal C-shaped arms 100;

[0053] The chip (6) is located on a horizontal strip on one side of the rectangular ring (1); and the metal radiation unit is located above the dielectric substrate (7).

[0054] In this example, the tag antenna is attached to the surface of the object to be marked, and after a preliminary frequency response test, the tag antenna in this state can be tuned according to the actual situation and needs. A fast and effective tuning method is to adjust the relevant dimensions of the first interdigital center metal band 4 and the second interdigital center metal band 5.

Claims

1. A miniaturized tunable RFID tag antenna embedded with an interdigitated structure, characterized in that: The tag antenna is a single-sided structure including a radiation unit, an RFID tag chip, and a dielectric substrate; The radiation unit is located on a dielectric substrate (7); the radiation unit is provided with a rectangular ring (1), a first L-shaped gradually bent arm (2), and a second L-shaped gradually bent arm (3); the rectangular ring (1) is located at the upper part of the central axis area of ​​the radiation unit, and an RFID tag chip (6) is provided at a horizontal strip of the rectangular ring; the middle of the horizontal arm end of the first L-shaped gradually bent arm is connected to a horizontal first interdigitated central metal strip (4), and the middle of the horizontal arm end of the second L-shaped gradually bent arm is connected to a horizontal second interdigitated central metal strip (5); The first L-shaped gradually bent arm (2) and the second L-shaped gradually bent arm (3) are located on one side of the rectangular ring and are connected to form an assembly A (101); the radiation unit on the other side of the rectangular ring is provided with an assembly B (102) whose top view shape is a mirror image of the assembly A; the middle parts of the ends of the two horizontal arms of the assembly B are respectively connected to the two horizontal C-shaped arms (100); the first interdigitated central metal belt and the second interdigitated central metal belt are respectively inserted into the gaps of the two horizontal C-shaped arms and are respectively combined with the two horizontal C-shaped arms to form the first interdigitated metal belt and the second interdigitated metal belt located at the central axis of the radiation unit.

2. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The rectangular ring (1) has a micro-notch etched in a horizontal strip on one side. The micro-notch is used to place a tag chip (6) and is connected to the rectangular ring (1). It is also used to achieve energy transmission between the tag antenna and the tag chip and adjust impedance matching between the two.

3. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The end of the first L-shaped gradually bent arm (2) and the head of the second L-shaped gradually bent arm (3) are connected to form an L-shaped gradually bent arm structure, and the entire L-shaped gradually bent arm structure is then connected to the rectangular ring (1). The L-shaped gradually bent arm structure is used to adjust the resonant frequency of the tag antenna.

4. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The line width, line spacing, vertical arm height and horizontal arm length of the first L-shaped gradually bent arm (2) and the second L-shaped gradually bent arm (3) can be set according to actual performance requirements, and the corresponding dimensional parameter values ​​can be the same or different.

5. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The first interdigitated central metal strip (4) and the second interdigitated central metal strip (5) respectively form two pairs of interdigitated structures with two horizontal C-shaped arms, which are used to achieve miniaturization of the tag antenna and tuning of the tag antenna during simulation and after manufacturing.

6. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The length and width of each of the first interdigitated metal strips and the second interdigitated central metal strips and the overall height of the two structures are set according to actual performance requirements, and the corresponding size parameter values ​​can be the same or different.

7. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The rectangular ring (1), the first L-shaped gradually bent arm (2), the second L-shaped gradually bent arm (3), the first interdigitated central metal belt (4), the second interdigitated central metal belt (5), and the two horizontal C-shaped arms are all formed from aluminum.

8. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The radiation unit is an etching structure on a dielectric substrate.

9. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The substrate is a flexible polymer film.

10. The miniaturized tunable RFID tag antenna embedded with an interdigitated structure according to claim 1, characterized in that: The tag antenna has a -10dB frequency band of 916MHz-924MHz in the UHF RFID working frequency band, a maximum power transmission coefficient of 99.9%, and a maximum gain of -5.25dBi.

Images