Miniaturized uhf rfid double-sided metal resistant tag antenna

Abstract

The application relates to a miniaturized ultra-high frequency RFID double-sided metal-resistant label antenna, which comprises a first radiation patch, a second radiation patch, a short-circuit surface, a short-circuit probe, a metal via, a plastic via, a chip, a first dielectric plate, a second dielectric plate and a metal surface; the first dielectric plate and the second dielectric plate are the same in size and are stacked together, a through hole is formed in the middle of the first dielectric plate; the first radiation patch and the second radiation patch are respectively attached to the upper surface of the first dielectric plate and the lower surface of the second dielectric plate; the chip is arranged at the center position of the upper surface of the second dielectric plate, and the metal surface is arranged on both sides of the chip; the short-circuit surface is arranged on the side wall of the through hole in the middle of the first dielectric plate; the short-circuit probe is arranged in the second dielectric plate and is connected with the second radiation patch and the metal surface at two ends; the metal via penetrates the first dielectric plate and the second dielectric plate and is connected with the first radiation patch and the second radiation patch; and the plastic via connects the first dielectric plate and the second dielectric plate. The label antenna has good double-sided metal-resistant performance, is flexible to use and has a wide application range.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a miniaturized UHF RFID double-sided anti-metal tag antenna. Background Technology

[0002] Radio Frequency Identification (RFID) is a communication technology that uses random multipath propagation of radio waves to identify specific targets and read / write related data. RFID systems are widely used in agricultural management, medical information tracking, crack detection, food retail, and anti-counterfeiting due to their longer identification range, faster reading speed, and higher storage capacity. RFID tags mainly consist of an antenna and a chip. Passive tags power their chips by receiving electromagnetic wave energy from the reader, enabling the tag to function properly.

[0003] While RFID technology shows great promise, it's still some distance from large-scale adoption. When an UHF RFID tag is placed in a metallic environment, the metal absorbs and reflects electromagnetic waves, altering the spatial and intensity distribution of the electromagnetic field. If the metal is close to the tag's antenna, the reflected electromagnetic waves superimpose with the original electromagnetic field, weakening it and creating an electromagnetic blind zone on the metal surface. Tags located in this blind zone are difficult to read. Secondly, according to metal boundary conditions, the magnetic field lines on the metal surface tend to be flat and approximately parallel to the surface. When a tag is attached to (or near) the metal surface, the antenna cannot "cut" the magnetic field lines to provide sufficient electromagnetic energy. Furthermore, when the antenna is very close to the metal plate, the mirror current cancels out the current on the antenna, causing a sharp change in the antenna's impedance performance. Simultaneously, the metal surface's effect on antenna inductance leads to reduced radiation resistance and lower radiation efficiency. Moreover, the passive tag's chip is directly connected to the antenna; their input impedances are functions of frequency, and the degree of conjugate matching directly affects the tag's performance. When ordinary tags are applied directly to metal surfaces, the aforementioned factors will significantly shorten the antenna's read / write distance, and greatly affect its directivity, bandwidth, and impedance. Therefore, in metallic environments, the antenna structure must be specially designed to allow electronic tags to be applied to metal surfaces.

[0004] Ultra-high frequency (UHF) anti-metal RFID tag antennas are mainly designed with microstrip antennas, planar inverted-F antennas (PIFA), or planar inverted-L antennas (PILA), which have advantages such as small size, low profile, ease of fabrication, and low cost. Meanwhile, with the deepening research on anti-metal tag antennas, foldable tag antennas are considered to achieve good anti-metal performance. These tag antennas have advantages such as thin profile, flexibility, ease of fabrication, and low cost, and can be flexibly applied in various metallic environments. Many tag structures based on metamaterial units have also been explored to mitigate the impact of backing metal on the tag. Common metamaterials include artificial magnetic conductors (AMC), electromagnetic band gaps (EBG), and split ring resonators (SRR). While the structures described above can ensure the tag antenna functions normally in various metallic environments, they only achieve single-sided anti-metal performance; that is, good anti-metal performance is only achieved when a specific side of the antenna is in contact with a metallic object. In practical applications, if the antenna is placed incorrectly on the surface of a metal object, it will be difficult for it to work properly. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized UHF RFID double-sided anti-metal tag antenna, which has good double-sided anti-metal performance, is flexible in use, and has a wide range of applications.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a miniaturized UHF RFID double-sided anti-metal tag antenna, comprising a first radiating patch, a second radiating patch, a short-circuit surface, a short-circuit probe, a metal via, a plastic via, a chip, a first dielectric substrate, a second dielectric substrate, and a metal surface; the first and second dielectric substrates are of the same size and are stacked together, with a through hole in the middle of the first dielectric substrate; the first radiating patch is attached to the upper surface of the first dielectric substrate, and the second radiating patch is attached to the lower surface of the second dielectric substrate; the chip is disposed at the center of the upper surface of the second dielectric substrate, and the metal surface is disposed on the second dielectric substrate and located on both sides of the chip; the short-circuit surface is disposed on the sidewall of the through hole in the middle of the first dielectric substrate; the short-circuit probe passes through the second dielectric substrate, with its two ends connected to the second radiating patch and the metal surface, respectively; the metal via penetrates the first and second dielectric substrates and connects the first and second radiating patches; the plastic via connects the first and second dielectric substrates.

[0007] Furthermore, the first radiating patch, the second radiating patch, the short-circuit surface, the short-circuit probe, the metal via, and the metal surface can each be made of metal materials of different thicknesses.

[0008] Furthermore, the first and second dielectric substrates can be made of different substrates, and the two dielectric substrates have the same thickness, shape, and size, and can be completely overlapped.

[0009] Furthermore, the first radiating patch is attached to the upper outer surface of the first dielectric substrate, and includes a plurality of slot structures thereon. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots. The second radiating patch is attached to the lower outer surface of the second dielectric substrate, and includes a plurality of slot structures thereon. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots.

[0010] Furthermore, the through hole is formed at the center of the first dielectric substrate, through which a portion of the upper surface of the second dielectric substrate can be seen directly from the top of the tag antenna. The shape and size of the portion of the upper surface are the same as the planar shape and size of the through hole.

[0011] Furthermore, the short-circuit surface includes two short-circuit wires, which are disposed on one side wall of the through hole in the middle of the first dielectric material. Their top ends are connected to the first radiating patch, and their bottom ends are connected to the metal surface.

[0012] Furthermore, the short-circuit probe penetrates the second dielectric substrate along its thickness direction, with its top end connected to the metal surface and its bottom end connected to the second radiating patch.

[0013] Furthermore, it includes multiple metal vias, each of which is embedded in the first dielectric substrate and the second dielectric substrate, with its top end connected to the first radiating patch and its bottom end connected to the second radiating patch.

[0014] Furthermore, it includes multiple plastic vias distributed at the four corners of the tag antenna. Each plastic via is embedded in the first dielectric substrate and the second dielectric substrate, with its top end connected to the first radiating patch and its bottom end connected to the second radiating patch, for tightly connecting the first dielectric substrate and the second dielectric substrate together.

[0015] Furthermore, the metal surface includes two arms located on the left and right sides of the chip, and the two ports of the chip are respectively connected to the two arms of the metal surface.

[0016] Compared with existing technologies, this invention has the following advantages: The tag antenna mainly consists of two radiating patches, located on the upper and lower surfaces of the antenna respectively. By placing a chip in the middle layer of the antenna, one end of the chip is connected to the first radiating patch through a metal surface and a short-circuit surface, and the other end is connected to the second radiating patch through a metal surface and a short-circuit probe, achieving good double-sided anti-metal performance for the tag antenna, facilitating its use in certain specific environments. Adding slot structures at appropriate positions on the first and second radiating patches can effectively tune the antenna's resonant frequency, improve the power transmission coefficient, and provide good matching adjustment, ensuring good performance regardless of which side of the radiating patch contacts the backing metal. The metal vias connecting the first and second radiating patches facilitate miniaturization of the antenna. This tag antenna has a simple structure, compact size, and good anti-metal performance when either side contacts a backing metal object. Furthermore, its usable frequency bands are covered by the application frequency bands of UHF RFID tag antennas in China, Europe, and the United States, making it suitable for application in complex industrial IoT fields. Attached Figure Description

[0017] Figure 1 This is a perspective view of a miniaturized UHF RFID double-sided anti-metal tag antenna according to an embodiment of the present invention. Figure 2 This is a top view of a miniaturized UHF RFID double-sided anti-metal tag antenna according to an embodiment of the present invention; Figure 3 This is a bottom view of the miniaturized UHF RFID double-sided anti-metal tag antenna according to an embodiment of the present invention; Figure 4 This is a front view of a miniaturized UHF RFID double-sided anti-metal tag antenna according to an embodiment of the present invention. Figure 5 This is a left view of a miniaturized UHF RFID double-sided anti-metal tag antenna according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the simulation results of the reflection coefficient when the first radiating patch is used as the radiating surface and the second radiating patch is in close contact with the surface of a metal object in an embodiment of the present invention. Figure 7 This is a schematic diagram of the simulation results of the reflection coefficient when the second radiating patch is used as the radiating surface and the first radiating patch is in close contact with the surface of a metal object in an embodiment of the present invention. Figure 8 This is a schematic diagram of the power transmission coefficient when the first radiating patch serves as the radiating surface and the second radiating patch is in close contact with the surface of a metal object in an embodiment of the present invention. Figure 9 This is a schematic diagram of the power transmission coefficient when the second radiating patch serves as the radiating surface and the first radiating patch is in close contact with the surface of a metal object in an embodiment of the present invention. Figure 10This is a schematic diagram of the reading distance when the first radiating patch serves as the radiating surface and the second radiating patch is in close contact with the surface of a metal object in an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the reading distance when the second radiating patch serves as the radiating surface and the first radiating patch is in close contact with the surface of a metal object, as shown in this embodiment of the invention. Figure 12 This is a radiation pattern in an embodiment of the present invention where the first radiating patch serves as the radiating surface and the second radiating patch is in close contact with the surface of a metal object. Figure 13 This is a radiation pattern in an embodiment of the present invention, where the second radiating patch serves as the radiating surface and the first radiating patch is in close contact with the surface of a metal object.

[0018] In the diagram: 1-First radiating patch; 2-Second radiating patch; 3-Short circuit surface; 4-Short circuit probe; 5-Metal via; 6-Plastic via; 7-Chip; 8-First dielectric substrate; 9-Second dielectric substrate; 10-Metal surface. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] like Figure 1-5 As shown, this embodiment provides a miniaturized UHF RFID double-sided anti-metal tag antenna, including a first radiating patch 1, a second radiating patch 2, a short-circuit surface 3, a short-circuit probe 4, a metal via 5, a plastic via 6, a chip 7, a first dielectric substrate 8, a second dielectric substrate 9, and a metal surface 10.

[0023] The first dielectric substrate 8 and the second dielectric substrate 9 are the same size and are stacked together, with the first dielectric substrate 8 located above the second dielectric substrate 9. A through hole is formed in the middle of the first dielectric substrate 8. A first radiating patch 1 is attached to the upper surface of the first dielectric substrate 8, and a second radiating patch 2 is attached to the lower surface of the second dielectric substrate 9. A chip 7 is disposed at the center of the upper surface of the second dielectric substrate 9, and a metal surface 10 is disposed on the second dielectric substrate 9 and located on both sides of the chip 7. A short-circuit surface 3 is disposed on the side wall of the through hole in the middle of the first dielectric substrate 8. A short-circuit probe 4 passes through the second dielectric substrate 9, and its two ends are connected to the second radiating patch 2 and the metal surface 10, respectively. A metal via 5 passes through the first dielectric substrate 8 and the second dielectric substrate 9 and connects the first radiating patch 1 and the second radiating patch 2. A plastic via 6 connects the first dielectric substrate 8 and the second dielectric substrate 9.

[0024] The first radiating patch 1 is attached to the upper outer surface of the first dielectric substrate 8, and includes several slot structures. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots.

[0025] The second radiating patch 2 is attached to the lower outer surface of the second dielectric substrate 9, and includes several slot structures. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots.

[0026] A through hole is formed at the center of the first dielectric substrate 8. Through the through hole, part of the upper surface of the second dielectric substrate 9 can be seen directly from the top of the tag antenna. The shape and size of the part of the upper surface are the same as the planar shape and size of the through hole.

[0027] The short-circuit surface 3 includes two short-circuit short wires, which are set on one side wall of the through hole in the middle of the first dielectric plate 8. The top end of the short-circuit surface 3 is connected to the first radiating patch 1, and the bottom end is connected to the metal surface 10.

[0028] The short-circuit probe 4 penetrates the second dielectric substrate 9 along the thickness direction of the second dielectric substrate 9, with its top end connected to the metal surface 10 and its bottom end connected to the second radiating patch 2.

[0029] The metal surface 10 includes two arms located on the left and right sides of the chip 7. The two ports of the chip 7 are respectively connected to the two arms of the metal surface 10. The chip 7 can be selected from multiple models suitable for the UHF RFID range.

[0030] In this embodiment, the tag antenna includes four metal vias 5, each of which is embedded in the first dielectric substrate 8 and the second dielectric substrate 9. Its top end is connected to the first radiating patch 1 and its bottom end is connected to the second radiating patch 2.

[0031] In this embodiment, the tag antenna includes four plastic vias 6 distributed at the four corners of the tag antenna. Each plastic via 6 is embedded in the first dielectric substrate 8 and the second dielectric substrate 9. Its top end is connected to the first radiating patch 1 and its bottom end is connected to the second radiating patch 2, which serves to fix the first dielectric substrate 8 and the second dielectric substrate 9 together.

[0032] Preferably, the first radiating patch 1, the second radiating patch 2, the short-circuit surface 3, the short-circuit probe 4, the metal via 5, and the metal surface 10 can be made of metal materials of different thicknesses, preferably copper or aluminum. The first dielectric substrate 8 and the second dielectric substrate 9 are made of FR4 or Rogers substrate, and the two dielectric substrates have the same thickness, shape, and size, and can be completely overlapped.

[0033] In this embodiment, the tag antenna measures 40mm × 28mm × 3.2mm.

[0034] like Figure 6-13 As shown in the simulation test, in this embodiment, when the first radiating patch 1 is used as the radiating surface and the second radiating patch 2 is in close contact with the surface of the metal object, the -10dB impedance bandwidth is 836MHz-941MHz, the power transmission coefficient is 98.1%, and the reading distance is 5.4m; when the second radiating patch 2 is used as the radiating surface and the second radiating patch 1 is in close contact with the surface of the metal object, the -10dB impedance bandwidth is 860MHz-937MHz, the power transmission coefficient is 99.9%, and the reading distance is 5.2m, and both have good directional radiation capabilities.

[0035] The miniaturized UHF RFID double-sided anti-metal tag antenna provided by this invention mainly consists of two parallel radiating patches of the same size, namely a first radiating patch 1 and a second radiating patch 2. The first radiating patch 1 is located on the upper outer surface of the designed tag antenna, which is also the upper outer surface of the dielectric substrate 8. The second radiating patch 2 is located on the lower outer surface of the designed tag antenna, which is also the lower outer surface of the dielectric substrate 9. The chip 7 is located in the middle layer of the designed tag antenna, which is also the upper outer surface of the dielectric substrate 9. Its positive and negative RF terminals are connected to the two arms of the metal surface 10, respectively. One arm of the metal surface 10 is connected to the first radiating patch 1 through a short-circuit surface 3, and the other arm is connected to the second radiating patch 2 through a short-circuit probe 4. When the tag antenna is placed in a metallic environment, the side in contact with the metal backing can be regarded as the ground plane of the tag antenna, while the other side can be regarded as the radiating surface of the tag antenna. This design of the tag antenna achieves good double-sided anti-metal performance. Adding slotted structures to the first radiating patch 1 and the second radiating patch 2 of the tag antenna effectively tunes the antenna's resonant frequency, improves the power transmission coefficient, and provides good matching adjustment. It maintains good performance regardless of which side of the radiating patch contacts the backing metal. The metal via 5 consists of four identical metal pillars that connect the first radiating patch 1 and the second radiating patch 2, facilitating antenna miniaturization. When either the first radiating patch 1 or the second radiating patch 2 is in close contact with the surface of a metal object, the antenna's operating frequency shift does not exceed the application frequency band. The operating frequency band covers the application frequency bands of UHF RFID tag antennas in China, Europe, and the United States. It is compact, simple in structure, and easy to manufacture, effectively meeting the application needs of the Industrial Internet of Things (IIoT) field.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A miniaturized UHF RFID double-sided anti-metal tag antenna, characterized in that, The system includes a first radiating patch (1), a second radiating patch (2), a short-circuit surface (3), a short-circuit probe (4), a metal via (5), a plastic via (6), a chip (7), a first dielectric substrate (8), a second dielectric substrate (9), and a metal surface (10). The first dielectric substrate (8) and the second dielectric substrate (9) are of the same size and are stacked together, with a through hole in the middle of the first dielectric substrate (8). The first radiating patch (1) is attached to the upper surface of the first dielectric substrate (8), and the second radiating patch (2) is attached to the lower surface of the second dielectric substrate (9). The chip (7) is located at the center of the upper surface of the second dielectric substrate (9), and the metal surface (10) 10) The short-circuit path (3) is disposed on the second dielectric substrate (9) and located on both sides of the chip (7); the short-circuit path (3) includes two short-circuit wires, which are disposed on one side wall of the through hole in the middle of the first dielectric substrate (8), with its top end connected to the first radiating patch (1) and its bottom end connected to the metal surface (10); the short-circuit probe (4) is inserted in the second dielectric substrate (9), with its two ends connected to the second radiating patch (2) and the metal surface (10) respectively; the metal via (5) passes through the first dielectric substrate (8) and the second dielectric substrate (9) and connects the first radiating patch (1) and the second radiating patch (2); the plastic via (6) connects the first dielectric substrate (8) and the second dielectric substrate (9); The first radiating patch (1) is attached to the upper outer surface of the first dielectric substrate (8), and includes several slot structures. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots. The second radiating patch (2) is attached to the lower outer surface of the second dielectric substrate (9), and includes several slot structures. The resonant frequency of the tag antenna can be effectively adjusted by adjusting the length and width of the slots. The through hole is opened at the center of the first dielectric substrate (8), and a portion of the upper surface of the second dielectric substrate (9) can be seen directly from the top of the tag antenna through the through hole. The shape and size of the portion of the upper surface are the same as the planar shape and size of the through hole. The short-circuit probe (4) penetrates the second dielectric plate (9) along the thickness direction of the second dielectric plate (9), with its top end connected to the metal surface (10) and its bottom end connected to the second radiating patch (2); It includes multiple metal vias (5) made of metal pillars. Each metal via (5) is embedded in the first dielectric plate (8) and the second dielectric plate (9). Its top end is connected to the first radiating patch (1) and its bottom end is connected to the second radiating patch (2). It includes multiple plastic vias (6) distributed at the four corners of the tag antenna. Each plastic via (6) is embedded in the first dielectric substrate (8) and the second dielectric substrate (9). Its top end is connected to the first radiating patch (1) and its bottom end is connected to the second radiating patch (2), which is used to tightly connect the first dielectric substrate (8) and the second dielectric substrate (9) together. The metal surface (10) includes two arms located on the left and right sides of the chip (7), and the two ports of the chip (7) are respectively connected to the two arms of the metal surface (10).

2. The miniaturized UHF RFID double-sided anti-metal tag antenna according to claim 1, characterized in that, The first radiating patch (1), the second radiating patch (2), the short-circuit surface (3), the short-circuit probe (4), the metal via (5), and the metal surface (10) are made of metal materials of different thicknesses.

3. The miniaturized UHF RFID double-sided anti-metal tag antenna according to claim 1, characterized in that, The first dielectric substrate (8) and the second dielectric substrate (9) are made of different substrates. The two dielectric substrates have the same thickness, shape and size and can be completely overlapped.

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