An enhanced ultra-high frequency antenna and platform fault tolerant optimized RFID tag

Abstract

The application provides an enhanced UHF antenna, which comprises an antenna substrate, a gap layer and a resonance substrate arranged in sequence; the resonance substrate is provided with a grounding metal layer on the side far from the antenna substrate, and is provided with a parallel microstrip resonance structure on the side close to the antenna substrate; the parallel microstrip resonance structure comprises three resonance frequency points in the UHF frequency band; the antenna substrate comprises an antenna network composed of a zigzag dipole and a resonance matching strip, and the corresponding impedance real part at 915 MHz is between 10 Ω and 20 Ω, and the impedance imaginary part is between 135 Ω and 155 Ω; the gap layer between the zigzag dipole and the parallel microstrip resonance structure is an air gap layer or a polystyrene foam plastic layer. The application also provides an RFID tag with platform fault tolerance optimization, which comprises the enhanced UHF antenna. The RFID tag of the application exhibits better characteristics in effective identification rate, identification efficiency and identification range.

Description

Technical Field

[0001] This invention relates to the field of RFID, specifically to an enhanced UHF antenna and a platform fault-tolerant optimized RFID tag. Background Technology

[0002] RFID technology is used in many fields such as intelligent transportation, smart manufacturing, logistics and distribution, and anti-counterfeiting and traceability. It is also considered an important cornerstone for realizing the Internet of Things. The accuracy of RFID tag identification is affected by many factors, such as the material of the attached object, detection distance, identification density, and frequency matching. However, its structural design is fundamental, and different structural designs will exhibit different identification efficiencies under the same conditions. For example, when identifying the numerous RFID tags associated with several goods stacked on a pallet, it may be impossible to completely identify or obtain all the tagged goods information at once. In such cases, it is necessary to increase the identification power or sensitivity of the RFID tag reader, reduce the detection distance, conduct multi-directional or multiple detections, or reduce the number of goods for batch testing in order to completely read the relevant RFID tag information and record and trace the flow of goods. If the goods contain metal or wooden containers, the RFID tags attached to the surface of the containers will also have reduced identification accuracy due to the reflection and dissipation of electromagnetic waves. When goods are transported from China to Europe and the United States, the identification frequency bands of RFID reading devices in different countries are different, and different materials have different reflection and dissipation of electromagnetic waves of different frequency bands, which also affects the identification accuracy of RFID tags.

[0003] With the development of technology, higher requirements have been placed on the identification efficiency of RFID tags. Antenna design is crucial for improving the effective identification rate and efficiency of RFID tags. However, most designs rely on simulation calculations based on the matching impedance of UHF RFID chips. Given the relatively small overall size of RFID tags, structural design is a challenge, especially considering applicability across multiple scenarios. Designs based on multiple simulations are difficult to manufacture and extremely expensive. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an enhanced UHF antenna and a platform-optimized fault-tolerant RFID tag. Its purpose is to solve the problems that the effective identification rate and efficiency of RFID tags do not meet the application needs and the identification range is too small in scenarios such as logistics, intelligent transportation, asset tracking and the Internet of Things.

[0005] Specifically, the present invention provides an enhanced UHF antenna comprising an antenna substrate, a gap layer, and a resonant substrate arranged in sequential layers; the side of the resonant substrate away from the antenna substrate is provided with a ground metal layer, and the side of the resonant substrate close to the antenna substrate is provided with a parallel microstrip resonant structure; the parallel microstrip resonant structure corresponds to three resonant frequency points in the UHF band; the antenna substrate comprises an antenna network composed of a zigzag dipole and a resonant matching strip, and the real part of the impedance at 915MHz is between 10Ω and 20Ω, and the imaginary part of the impedance is between 135Ω and 155Ω; the gap layer between the zigzag dipole and the parallel microstrip resonant structure is an air gap layer or a polystyrene foam layer.

[0006] Furthermore, the parallel microstrip resonant structure comprises several rectangular metal strips of the same length arranged in parallel, and any two adjacent metal strips each have two dimensions: a first width and a second width.

[0007] Furthermore, the center dimension of the first width is 2.5mm, and the center dimension of the second width is 2mm; the absolute value of the error between the first width and the second width is not greater than 0.2mm; the center dimension of the gap between adjacent metal strips is 0.5mm, and the absolute value of the error does not exceed 0.1mm.

[0008] Furthermore, the three resonant frequency points are between 800MHz and 960MHz, and the minimum frequency interval between adjacent resonant frequencies is not less than 5MHz.

[0009] Furthermore, the outer edge of the zigzag dipole is rectangular in shape, matching the size of the outer edge of the parallel microstrip resonant structure, and they are stacked vertically in corresponding layers. The zigzag dipole has an axially symmetric structure with its midline as the axis of symmetry. An inverted U-shaped groove is formed in the middle of the zigzag dipole, and the resonant matching strip is located in the inverted U-shaped groove. The top of the protrusion of the zigzag dipole corresponding to the inverted U-shaped groove is also provided with an extension, which includes a first T-shaped extension and a second T-shaped extension. The horizontal portions of the first T-shaped extension and the second T-shaped extension are flush with each other and adjacent to each other, and their vertical portions are connected to the top of the protrusion of the inverted U-shaped groove. The zigzag dipole has at least one air gap groove on each side of the inverted U-shaped groove.

[0010] The present invention also proposes a platform-fault-tolerant optimized RFID tag, which includes the aforementioned enhanced UHF antenna.

[0011] Furthermore, it also includes an RFID chip; the RFID chip is disposed on the antenna substrate and is communicatively connected to the antenna network.

[0012] When an RFID tag is placed on a metal surface, the parallel microstrip resonant structure and the gap layer maintain the distance between the antenna network and the metal surface. The resonant matching strip can be configured as a U-shaped structure to match the inverted U-shaped slot, which can adjust the characteristic impedance of the antenna network. By placing the parallel microstrip resonant structure close to the antenna network, resonance can be generated near the resonance point, enhancing the signal received by the antenna network, thereby increasing the bandwidth and extending the identification distance of the RFID tag. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the antenna substrate in Example 1.

[0014] Figure 2 This is a schematic diagram of the resonant substrate in Example 1.

[0015] Figure 3 This is a schematic diagram of the stacking of the antenna substrate, the gap layer, and the resonant substrate in Example 1.

[0016] Figure 4 The dimensions of the antenna substrate, gap layer, and resonant substrate in Example 1 are marked.

[0017] Figure 5 The graph shows the characteristic value curves of the parallel microstrip resonant structure in Example 1.

[0018] Figure 6 This is a graph showing the characteristic values ​​of the enhanced UHF antenna in Example 1.

[0019] Figure 7 This is a comparison diagram showing the effect of a parallel microstrip resonant structure on a single-layer RFID tag mounted on a metal plate.

[0020] Figure 8 The reading range of the RFID tag optimized for platform fault tolerance in Example 1 was measured after it was placed on different environmental surfaces. Detailed Implementation

[0021] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Example 1

[0023] An enhanced ultra-high frequency antenna includes an antenna substrate, a spacer layer, and a resonant substrate arranged in sequential layers. The antenna substrate and resonant substrate are made of fiberglass or epoxy resin, facilitating PCB fabrication of the circuitry and the implementation of the spacer layer. The antenna substrate has a thickness of 0.5 mm, the spacer layer has a thickness of 2.5 mm, and the resonant substrate has a thickness of 1 mm. The effective electrical structural dimensions of the antenna substrate and the resonant substrate are matched overall. The resonant substrate has a grounding metal layer on the side furthest from the antenna substrate. Figure 2 As shown, the resonant substrate 7 has a parallel microstrip resonant structure on the side close to the antenna substrate; the parallel microstrip resonant structure has three resonant frequency points in the UHF band; the three resonant frequency points are between 800MHz and 960MHz, and the minimum frequency interval between adjacent resonant frequencies is not less than 5MHz.

[0024] like Figure 1 As shown, the antenna substrate 1 includes an antenna network composed of a zigzag dipole 2 and a resonant matching strip 3, as follows: Figure 1 As shown, the outer edge of the zigzag dipole 2 is rectangular, matching the size of the outer edge of the parallel microstrip resonant structure, and they are stacked vertically. The zigzag dipole 2 has an axially symmetrical structure with its length's midline as the axis of symmetry. In actual design and manufacturing, some dimensions can be slightly adjusted according to the actual application. An inverted U-shaped groove is formed in the middle of the zigzag dipole 2, and the resonant matching strip 3 is located in the inverted U-shaped groove. The top of the protrusion 4 of the zigzag dipole corresponding to the inverted U-shaped groove also has an extension, which includes a first T-shaped extension 5 and a second T-shaped extension 6. The horizontal portions of the first T-shaped extension 5 and the second T-shaped extension 6 are flush and adjacent, and the gap can be used for printing RFID chips, and RFID tags can also be attached to the antenna substrate. The first T-shaped extension 5 and the second T-shaped extension 6... The vertical portions of part 6 are all connected to the top of the protrusion 4 of the inverted U-shaped slot; the vertical portion of the first T-shaped extension 5 is not connected to the midpoint of its horizontal portion, and the structure of the second T-shaped extension 6 is similar; the zigzag dipole has at least one air gap slot 101 on each side of the inverted U-shaped slot; the adjustment of the distance between the vertical portions of the air gap slot 101, the first T-shaped extension 5, and the second T-shaped extension 6, and the indentation 102 at the top of the protrusion 4 of the inverted U-shaped slot help to adjust the inductive reactance at high frequencies and set the resonant frequency of the antenna. The real part of the impedance of the antenna network at 915MHz is between 10Ω and 20Ω, and the imaginary part is between 135Ω and 155Ω; the impedance designed in this embodiment is between 14-140Ω.

[0025] The parallel microstrip resonant structure comprises several parallel rectangular metal strips of the same length. Any two adjacent metal strips each have two dimensions: a first width and a second width. The center dimension of the first width is 2.5 mm, and the center dimension of the second width is 2 mm. The absolute value of the error between the first width and the second width is no greater than 0.2 mm. Figure 2In the design, there are two rectangular metal strips: 8 with a width of 2mm and 9 with a width of 2.5mm. During actual production, the gap between adjacent metal strips can be kept consistent, with a center dimension of 0.5mm and an absolute error value not exceeding 0.1mm. Alternatively, two gaps can be set. One option is to group rectangular metal strips of the first width with those of the second width, with a 0.5mm gap within each group and a 1mm gap between all groups. Due to the overall dimensional inconsistencies, CST Microwave Studio can be used to optimize the length, width, and gap of each rectangular metal strip during actual design and production.

[0026] The gap layer between the tortuous dipole and the parallel microstrip resonant structure is either an air gap layer or a polystyrene foam layer with a dielectric constant close to that of air, and the thickness of the gap layer is 2.5 mm. Figure 3 The diagram shows an antenna network 11 on antenna substrate 1, a parallel microstrip resonant structure on resonant substrate 7, and a grounding metal layer. A gap layer separates antenna substrate 1 from resonant substrate 7.

[0027] In this embodiment, the enhanced UHF antenna corresponds to three resonant frequency points in the UHF band, specifically 925MHz, 905MHz, and 845MHz; the antenna dimensions in this embodiment are as follows, and the relevant dimension labels can be found in the original document. Figure 4 ;

[0028]

[0029] After obtaining the gap value using CST Microwave Studio, the eigenvalue diagram of the parallel microstrip resonant structure configuration under perfect conductor boundary conditions is shown. Model 1, Model 2, and Model 3 represent resonance at 925MHz, 905MHz, and 845MHz, respectively. For frequency characteristics, see [link to frequency response diagram]. Figure 5 , Figure 6 As shown, Figure 7 This demonstrates the enhancement effect of the parallel microstrip resonant structure on the frequency selectivity of the antenna network.

[0030] This embodiment also provides a platform-optimized fault-tolerant RFID tag. The tag's overall dimensions are between 80 and 88 mm in length, 26 and 30 mm in width, and no more than 5 mm in thickness. It includes the aforementioned enhanced UHF antenna. In one embodiment, the RFID chip is attached to the antenna substrate; in another embodiment, the RFID chip is printed on the antenna substrate and communicatively connected to the enhanced UHF antenna. The RFID chip is connected to the antenna network, and the parallel microstrip resonant structure acts as a parasitic element. Figure 7As shown, the platform's fault-tolerant optimized RFID tags were applied to different environmental tests. The reading range was 15m in air, 14m on metal, and 13.5m on glass and other low dielectric constant re-encoded tags. The tags performed well in simulated harsh environments, including metal mounting, and demonstrated good recognition accuracy and efficiency. In addition, the multiple frequency responses are compatible with RFID reading devices in different countries, making it widely applicable. Furthermore, the entire design does not involve any through holes, short-circuit walls, or short-circuit pins, making it easy to manufacture, low in cost, and convenient to promote.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An enhanced ultra-high frequency antenna, characterized in that: The device comprises an antenna substrate, a gap layer, and a resonant substrate arranged in a sequentially stacked configuration. The resonant substrate has a ground metal layer on its side away from the antenna substrate and a parallel microstrip resonant structure on its side close to the antenna substrate. The parallel microstrip resonant structure corresponds to three resonant frequency points between 800MHz and 960MHz, with a minimum frequency interval of not less than 5MHz between adjacent resonant frequencies. The antenna substrate comprises an antenna network consisting of a zigzag dipole and a resonant matching strip, with a real impedance between 10Ω and 20Ω and an imaginary impedance between 135Ω and 155Ω at 915MHz. The gap layer between the zigzag dipole and the parallel microstrip resonant structure is either an air gap layer or a polystyrene foam layer.

2. The enhanced UHF antenna as described in claim 1, characterized in that: The parallel microstrip resonant structure comprises several rectangular metal strips of the same length arranged in parallel, and any two adjacent metal strips each have two dimensions: a first width and a second width.

3. An enhanced UHF antenna as described in claim 2, characterized in that: The center dimension of the first width is 2.5mm, and the center dimension of the second width is 2mm; the absolute value of the error between the first width and the second width is no greater than 0.2mm.

4. An enhanced UHF antenna as described in claim 1, characterized in that: The thickness of the antenna substrate is between 0.3 mm and 0.6 mm, the thickness of the gap layer is between 2 mm and 3 mm, and the thickness of the resonant substrate is between 0.6 mm and 1.5 mm.

5. An enhanced UHF antenna as described in claim 1, characterized in that: The antenna substrate and resonant substrate are made of fiberglass board or epoxy resin board.

6. An enhanced UHF antenna as described in claim 1, characterized in that: The outer edge of the zigzag dipole is rectangular in shape, matching the size of the outer edge of the parallel microstrip resonant structure, and they are stacked vertically in corresponding layers. The zigzag dipole has an axially symmetric structure with its midline as the axis of symmetry. An inverted U-shaped groove is formed in the middle of the zigzag dipole, and the resonant matching strip is located in the inverted U-shaped groove. The top of the protrusion of the zigzag dipole corresponding to the inverted U-shaped groove is also provided with an extension, which includes a first T-shaped extension and a second T-shaped extension. The horizontal portions of the first T-shaped extension and the second T-shaped extension are flush with each other and adjacent to each other, and their vertical portions are connected to the top of the protrusion of the inverted U-shaped groove. The zigzag dipole has at least one air gap groove on each side of the inverted U-shaped groove.

7. A platform-fault-tolerant optimized RFID tag, characterized in that: It includes an enhanced UHF antenna as described in any one of claims 1 to 6.

8. The platform fault-tolerant optimized RFID tag as described in claim 7, characterized in that: It also includes an RFID chip; the RFID chip is disposed on the antenna substrate and is communicatively connected to the antenna network.

9. The platform fault-tolerant optimized RFID tag as described in claim 7, characterized in that: The overall dimensions of the label are between 80 and 88 mm in length, between 26 and 30 mm in width, and no more than 5 mm in thickness.

Images