An ultra-thin flexible anti-metal RFID tag antenna

Abstract

The present invention provides an ultra-thin flexible anti-metal RFID tag antenna, wherein the antenna radiation unit, metal grounding wire and metal floor of the tag antenna are connected in one piece, a metal foil with an insulating film as a substrate is first etched into a plane structure, the plane structure is then folded and then glued to the surface of a soft thin-sheet dielectric substrate to form its three-dimensional structure, the antenna radiation unit is located on the upper surface of the dielectric substrate, and is connected to the metal floor located on the lower surface of the dielectric substrate through the metal grounding wire on the side of the dielectric substrate; the antenna radiation unit comprises a first C-shaped impedance matching structure (3), a second C-shaped impedance matching structure (4), a long rectangular slot sheet and a short rectangular slot sheet, the openings of which are arranged opposite to each other to form a "U"-shaped structure; the upper ends of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure are respectively connected to the two side ends of the tag chip (9); the dielectric substrate thickness of the present invention is only 0.5 mm, and it still has good anti-metal performance and low sensitivity at a thickness of 0.5 mm.

Description

Technical Field

[0001] The invention relates to the technical field of wireless communications, in particular to an ultra-thin flexible anti-metal RFID tag antenna. Background Art

[0002] Radio Frequency Identification (RFID), as a short-range wireless communication technology, is widely used in industrial automation, medical treatment, transportation control and management and other fields. A general UHF RFID system consists of three parts: a control terminal, an RFID reader and an RFID tag. The control terminal is mainly responsible for controlling the RFID reader, thereby realizing the reading and writing operations of the RFID tag; the RFID reader is mainly used to provide energy to the tag, communicate with the tag, and realize communication with the computer; the RFID tag is an electronic device in the system that is used to store identifiable data and can complete related operations such as reading data or writing data.

[0003] RFID tags are usually composed of a tag chip and a tag antenna. The relevant information of the identified object is stored in the tag chip, while the tag antenna is responsible for obtaining enough energy from the electromagnetic waves to enable the tag chip to enter a normal working state and complete the reception and transmission of radio frequency signals, so that the RFID tag and even the RFID system can work normally. The tag can receive the electromagnetic waves emitted by the RFID reader and complete the information exchange between the reader and the reader.

[0004] During the use of the tag antenna, it is inevitable that it will come into contact with metal objects, which will have a huge impact on the performance of ordinary RFID tag antennas, causing the tags to not be read normally, greatly limiting the scope and environment of use of radio frequency identification technology. When the RFID tag antenna is attached to a metal surface, part of the energy of the signal emitted by the reader will be absorbed by the metal surface, resulting in insufficient energy to activate the tag; another part of the signal will be reflected by the metal surface, and the phase of the reflected signal will be opposite to the phase of the incident wave, resulting in cancellation, causing the tag to lose receiving energy and fail to work properly.

[0005] Currently, the performance of RFID tag antennas cannot meet the application requirements of special fields, such as a type of tag antenna that is thin, bendable, and has good metal resistance. Summary of the invention

[0006] The present invention provides an ultra-thin flexible anti-metal RFID tag antenna, the dielectric substrate thickness of which is only 0.5 mm, and the antenna still has good anti-metal performance and low sensitivity at a thickness of 0.5 mm.

[0007] The present invention adopts the following technical solutions.

[0008] An ultra-thin flexible anti-metal RFID tag antenna, wherein the antenna radiation unit (2), the metal grounding wire (7), and the metal floor (8) of the tag antenna are integrally connected, a metal foil with an insulating film as a substrate is first etched into a planar structure, the planar structure is then folded and then glued to the surface of a soft thin-sheet dielectric substrate (1) to form a three-dimensional structure, the antenna radiation unit is located on the upper surface of the dielectric substrate, and is connected to the metal floor located on the lower surface of the dielectric substrate via a metal grounding wire on the side of the dielectric substrate;

[0009] The antenna radiation unit comprises a first C-shaped impedance matching structure (3) and a second C-shaped impedance matching structure (4) whose openings are arranged opposite to each other to form a "U"-shaped structure; the lower end of the first C-shaped impedance matching structure is connected to a metal grounding wire via a long rectangular slot (5) on the upper surface of a dielectric substrate; the lower end of the second C-shaped impedance matching structure is connected to a short rectangular slot (6) on the upper surface of the dielectric substrate; the long rectangular slot and the short rectangular slot are parallel to each other; the upper ends of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure are respectively connected to two side ends of a tag chip (9).

[0010] The metal foil is aluminum foil, and the substrate is PET film.

[0011] The dielectric substrate 1 is a flexible foam substrate with a thickness of 0.5 mm.

[0012] The length of the metal grounding wire ranges from 1 mm to 30 mm.

[0013] The tag antenna adjusts the input impedance of the tag antenna by adjusting the length and width of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure to achieve impedance matching between the tag chip and the tag antenna. The tag antenna works in the UHF ultra-high frequency band by adjusting the length and width of the long rectangular slot. The resonance point of the tag antenna is roughly adjusted by adjusting the contact area between the long rectangular slot and the metal grounding wire.

[0014] The resonant frequency of the tag antenna can be precisely adjusted by adjusting the length and width of the short rectangular slot.

[0015] The length of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure is set in the range of 1 mm to 20 mm, and the width is set in the range of 1 mm to 15 mm;

[0016] The long rectangular slot is located in the center of the left side of the antenna radiation unit, and its length is set in the range of 1mm to 40mm, and its width is set in the range of 1mm to 4mm.

[0017] The short rectangular slot is not connected to the metal grounding wire.

[0018] The resonant frequency of the tag antenna ranges from 910 MHz to 920 MHz.

[0019] The length of the short rectangular slot is set in the range of 1mm to 40mm, and the width is set in the range of 1mm to 4mm.

[0020] In the present invention, the first C-shaped impedance matching structure and the second C-shaped impedance matching structure form a "U-shaped" structure, which can not only achieve the purpose of impedance matching more accurately, but also increase the electrical length of the tag antenna surface like a conventional rectangular slot, reduce the size of the tag antenna, and help to achieve the design requirements of ultra-thin tag antennas. Compared with the traditional rectangular slot, the "U-shaped" structure can not only perform impedance matching more accurately, but also increase the area of ​​the tag antenna radiation unit, which is beneficial for the tag antenna to receive signals, improve the gain of the tag antenna, and achieve better anti-metal performance.

[0021] In the present invention, the long rectangular slot is connected to a metal short ground wire on one side and to a first C-shaped impedance matching structure on the other side. It is located in the center of one side of the antenna radiation unit, and divides the antenna radiation unit into two upper and lower areas, which can effectively increase the surface electrical length of the tag antenna and reduce the size of the tag antenna. By adjusting the contact area between the long rectangular slot and the metal short wire, the resonance point of the tag antenna can be effectively coarse-tuned.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention is an ultra-thin flexible anti-metal RFID tag antenna, the radiation unit of the tag antenna is etched on a metal aluminum foil, the metal aluminum foil is folded and pasted on a flexible foam dielectric substrate with a thickness of 0.5 mm, and the overall size of the antenna is 60 mm × 30 mm × 0.5 mm. The antenna has good anti-metal performance, compact size and low manufacturing cost. The first C-shaped impedance matching structure and the second C-shaped impedance matching structure are relatively arranged to form a "loop"-shaped structure. Compared with the traditional rectangular slot, while increasing the electrical length of the antenna surface, the radiation area is maintained as large as possible, so that the area of ​​the tag antenna receiving the signal is larger, ensuring the good anti-metal performance of the tag antenna, and the minimum sensitivity of -9.6 dBm can be achieved in the actual measurement of the metal environment; by adjusting the length and width of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure, the impedance of the tag antenna can be adjusted to ensure the impedance matching between the tag chip and the tag antenna.

[0024] The ultra-thin flexible anti-metal RFID tag antenna proposed by the present invention can still achieve good anti-metal performance and low sensitivity while reducing the overall size and having a thickness of only 0.5 mm.

[0025] The present invention realizes an ultra-thin flexible anti-metal RFID tag antenna on a 0.5mm dielectric substrate, achieves the purpose of impedance matching of the tag chip, has good anti-metal performance, and the minimum sensitivity can reach -9.6dBm in actual measurement in a metal environment. The tag antenna can be covered by the application frequency band of my country's ultra-high frequency RFID tag antenna, realizing an ultra-thin flexible anti-metal RFID tag antenna. The antenna has a simple structure, low cost, and is easy to mass produce, and is suitable for most anti-metal scenarios. 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] Attached Figure 1 A three-dimensional schematic diagram of an embodiment of the present invention;

[0028] Attached Figure 2 It is a front view schematic diagram of an embodiment of the present invention;

[0029] Attached Figure 3 It is a left side schematic diagram of an embodiment of the present invention;

[0030] Attached Figure 4 A schematic top view of an embodiment of the present invention;

[0031] Attached Figure 5 is a schematic diagram of impedance matching simulation results of a tag antenna provided by an embodiment of the present invention;

[0032] Attached Figure 6 A schematic diagram of the radiation direction of an embodiment of the present invention in a metal environment;

[0033] Attached Figure 7 This is a schematic diagram of actual measurement using Tagformance Pro in a metal environment according to an embodiment of the present invention;

[0034] Attached Figure 8 It is a schematic diagram of the tag antenna sensitivity in a metal environment according to an embodiment of the present invention;

[0035] Attached Fig. 9 This is a schematic diagram of the theoretical reading distance of the tag antenna in a metal environment according to an embodiment of the present invention;

[0036] In the figure: 1- dielectric substrate; 2- antenna radiation unit; 3- first C-shaped impedance matching structure; 4- second C-shaped impedance matching structure; 5- long rectangular slot; 6- short rectangular slot; 7- metal grounding wire; 8- metal floor; 9- tag chip. DETAILED DESCRIPTION

[0037] As shown in the figure, an ultra-thin flexible anti-metal RFID tag antenna, the antenna radiation unit 2, the metal grounding wire 7, and the metal floor 8 of the tag antenna are connected in one piece, a metal foil with an insulating film as a substrate is first etched into a plane structure, and the plane structure is then folded and glued to the surface of a soft thin-sheet dielectric substrate 1 to form its three-dimensional structure, the antenna radiation unit is located on the upper surface of the dielectric substrate, and is connected to the metal floor located on the lower surface of the dielectric substrate through the metal grounding wire on the side of the dielectric substrate;

[0038] The antenna radiation unit includes a first C-shaped impedance matching structure 3 and a second C-shaped impedance matching structure 4, which are opened and arranged to form a "U"-shaped structure; the lower end of the first C-shaped impedance matching structure is connected to the metal grounding wire through a long rectangular slot 5 on the upper surface of the dielectric substrate; the lower end of the second C-shaped impedance matching structure is connected to a short rectangular slot 6 on the upper surface of the dielectric substrate; the long rectangular slot and the short rectangular slot are parallel to each other; the upper ends of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure are respectively connected to the two side ends of the tag chip 9.

[0039] The metal foil is aluminum foil, and the substrate is PET film.

[0040] The dielectric substrate 1 is a flexible foam substrate with a thickness of 0.5 mm.

[0041] The length of the metal grounding wire ranges from 1 mm to 30 mm.

[0042] The tag antenna adjusts the input impedance of the tag antenna by adjusting the length and width of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure to achieve impedance matching between the tag chip and the tag antenna. The tag antenna works in the UHF ultra-high frequency band by adjusting the length and width of the long rectangular slot. The resonance point of the tag antenna is roughly adjusted by adjusting the contact area between the long rectangular slot and the metal grounding wire.

[0043] The resonant frequency of the tag antenna can be precisely adjusted by adjusting the length and width of the short rectangular slot.

[0044] The length of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure is set in the range of 1 mm to 20 mm, and the width is set in the range of 1 mm to 15 mm;

[0045] The long rectangular slot is located in the center of the left side of the antenna radiation unit, and its length is set in the range of 1mm to 40mm, and its width is set in the range of 1mm to 4mm.

[0046] The short rectangular slot is not connected to the metal grounding wire.

[0047] The resonant frequency of the tag antenna ranges from 910 MHz to 920 MHz.

[0048] The length of the short rectangular slot is set in the range of 1mm to 40mm, and the width is set in the range of 1mm to 4mm.

Claims

1. An ultra-thin flexible anti-metal RFID tag antenna, characterized in that: The antenna radiation unit (2), the metal grounding wire (7), and the metal floor (8) of the tag antenna are integrally connected. A metal foil with an insulating film as a substrate is first etched into a planar structure. The planar structure is then folded and then glued to the surface of a soft thin-sheet dielectric substrate (1) to form a three-dimensional structure. The antenna radiation unit is located on the upper surface of the dielectric substrate and is connected to the metal floor located on the lower surface of the dielectric substrate via a metal grounding wire on the side of the dielectric substrate. The antenna radiation unit comprises a first C-shaped impedance matching structure (3) and a second C-shaped impedance matching structure (4) whose openings are arranged opposite to each other to form a "U"-shaped structure; the lower end of the first C-shaped impedance matching structure is connected to a metal grounding wire via a long rectangular slot (5) on the upper surface of a dielectric substrate; the lower end of the second C-shaped impedance matching structure is connected to a short rectangular slot (6) on the upper surface of the dielectric substrate; the long rectangular slot and the short rectangular slot are parallel to each other; the upper ends of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure are respectively connected to the two side ends of a tag chip (9).

2. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The metal foil is aluminum foil, and the substrate is PET film.

3. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The dielectric substrate (1) is a flexible foam substrate with a thickness of 0.5 mm.

4. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The length of the metal grounding wire ranges from 1 mm to 30 mm.

5. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The tag antenna adjusts the input impedance of the tag antenna by adjusting the length and width of the first C-shaped impedance matching structure and the second C-shaped impedance matching structure to achieve impedance matching between the tag chip and the tag antenna. The tag antenna works in the UHF ultra-high frequency band by adjusting the length and width of the long rectangular slot. The resonance point of the tag antenna is roughly adjusted by adjusting the contact area between the long rectangular slot and the metal grounding wire. The resonant frequency of the tag antenna can be precisely adjusted by adjusting the length and width of the short rectangular slot.

6. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The lengths of the first C-type impedance matching structure and the second C-type impedance matching structure are set in the range of 1 mm to 20 mm, and the widths are set in the range of 1 mm to 15 mm.

7. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The long rectangular slot is located in the center of the left side of the antenna radiation unit, and its length is set in the range of 1mm to 40mm, and its width is set in the range of 1mm to 4mm.

8. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The short rectangular slot is not connected to the metal grounding wire.

9. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The resonant frequency of the tag antenna ranges from 910MHz to 920MHz.

10. The ultra-thin flexible anti-metal RFID tag antenna according to claim 1, characterized in that: The length of the short rectangular slot is set in the range of 1mm to 40mm, and the width is set in the range of 1mm to 4mm.

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