CN219534863U - Miniaturized high-gain ultrahigh frequency antenna and tag - Google Patents

Abstract

The utility model discloses a miniaturized high-gain ultra-high frequency antenna and a tag, which include a resonant frequency point tuning structure and an impedance matching tuning structure; the impedance matching tuning structure includes a folded stub structure arranged in an inner layer, and the The resonant frequency point tuning structure includes a horizontal two-way folded dipole structure and a vertical two-way folded dipole structure; the horizontally opposite sides of the folded stub structure are respectively connected to the horizontal two-way folded dipole structure, and the vertically opposite sides are respectively connected to the vertical two-way Folded dipole structure; the UHF antenna is different from the traditional curved dipole structure, and can effectively solve the design problems of tag antenna miniaturization, high gain, and bandwidth under the condition of small size.

Description

A miniaturized high-gain UHF antenna and tag

technical field

The utility model relates to the technical field of antennas, in particular to a miniaturized high-gain ultra-high frequency antenna and a label.

Background technique

Radio Frequency Identification (RFID) is a non-contact automatic identification technology realized by radio frequency communication. ) to read and write, so as to achieve the purpose of identifying targets and exchanging data. It includes two main parts: electronic tag (tag) and reader (reader). The coded tag and reader perform non-contact data transmission through the antenna to complete the automatic identification process at a certain distance.

The RFID electronic tag includes two parts: the tag antenna and the chip. The tag antenna establishes communication with the identification system through wireless electromagnetic wave signals, receives commands and data from the identification system, and transmits the target object information stored in the electronic tag chip to the identification system. In order to realize the storage, management and control of target object information; RFID tag antennas are divided into metal etching antennas, printed antennas, and copper-plated antennas due to different materials and manufacturing processes; RFID tag antennas are an important part of the RFID system. It plays a key role in the process of realizing data communication, so the antenna design is the key to the application of the whole RFlD system.

Among them, the UHF-RFID tag antenna is widely used in fields that need to collect and exchange a large amount of information, such as transportation, warehousing and logistics, Internet of Things, and animal husbandry, due to its high operating frequency and more data and energy interaction between the antenna and the reader. wait. And the omnidirectionality of the tag antenna provides a stable guarantee for the efficiency and accuracy of a large amount of information interaction. At the same time, if the electronic tag antenna wants to have a long reading distance and a good reading effect, it is usually necessary to increase the size of the electronic tag antenna. However, as the degree of circuit integration becomes higher and higher, the packaging system and the antenna chip are gradually miniaturized. The size of the matching tag antenna can be designed smaller and smaller, therefore, how to improve the performance of the miniaturized UHF-RFID tag antenna has also become a problem of concern.

Common bent dipole tag antennas are miniaturized through traditional one-way bending technology, but the degree of miniaturization achieved by such one-way folding is limited, and it will lead to problems such as reduced antenna gain and radiation efficiency.

Utility model content

Based on the technical problems in the background technology, the utility model proposes a miniaturized high-gain UHF antenna and tag, which can have the characteristics of high gain, bandwidth and compactness under the condition of small size.

The utility model proposes a miniaturized high-gain UHF antenna, which includes a resonant frequency point tuning structure and an impedance matching tuning structure; the impedance matching tuning structure includes a folded stub structure arranged on the inner layer, and the resonant frequency The point tuning structure includes a horizontal two-way folded dipole structure and a vertical two-way folded dipole structure; the horizontally opposite sides of the folded stub structure are respectively connected to the horizontal two-way folded dipole structure, and the vertically opposite sides are respectively connected to the vertical two-way folded dipole structure. pole structure.

Further, the impedance matching tuning structure also includes a horizontal capacitive load and a vertical capacitive load. The two-way folded dipole structure is connected at the end remote from the folded stub structure.

Further, the resonant frequency point tuning structure further includes a first metal arm, a second metal arm and a third metal arm, the first metal arm is arranged under the folded stub structure to support the folded stub structure, the first metal arm The two ends of the second metal arm are respectively connected to the horizontal end of the first metal arm and the end of the horizontal two-way folded dipole structure, and the two ends of the third metal arm are respectively connected to the vertical end of the first metal arm and the vertical two-way folded dipole structure. The ends of the dipole structure are connected, and the chip is arranged on the first metal arm.

Further, the resonant frequency point tuning structure also includes a first arc-shaped connecting arm and a second arc-shaped connecting arm, and the two ends of the first arc-shaped connecting arm are respectively connected to one of the first metal arms close to the folded stub structure The end is connected to the end of one of the vertical two-way folded dipole structures, and the second arc-shaped connecting arm is respectively connected to one of the first metal arms near the end of the folded stub structure and the other vertical two-way folded dipole structure end connections.

Further, the first metal arm and the second metal arm are placed horizontally.

Further, the horizontal two-way folded dipole structure and the vertical two-way folded dipole structure are arranged orthogonally.

Furthermore, the horizontal two-way folded dipole structure is obtained by rotating the vertical two-way folded dipole structure by 90 degrees.

Further, both the horizontal bifold folded dipole structure and the vertical bidirectional folded dipole structure are serpentine stacked structures.

Further, a miniaturized high-gain UHF tag includes a substrate, an antenna layer and a chip, the antenna layer and the chip are etched on the upper surface of the substrate, and the antenna layer adopts the UHF antenna as described above.

The advantages of the miniaturized high-gain UHF antenna and tag provided by the utility model are: the miniaturized high-gain UHF antenna and tag provided in the structure of the utility model, the horizontal bidirectional folded dipole structure and the vertical The basic structure of bidirectional folded dipole structure loaded with capacitive load realizes the miniaturization of the antenna. By first adjusting the parameters in the resonant frequency point tuning structure and providing different equivalent capacitance and inductance values, the required antenna resonance can be preliminarily realized. point; and then by adjusting the various structural parameters in the impedance matching tuning structure, the input resistance and reactance of the antenna can be increased at the same time, and finally a good impedance matching with the chip can be achieved, achieving higher gain, bandwidth and Impedance matching characteristics, different from the traditional bent dipole structure, can effectively solve the design problems of tag antenna miniaturization, high gain, bandwidth, etc. under the condition of small size, it has the maximum gain at 915MHz, and can achieve a long distance Therefore, the UHF antenna has the characteristics of simple structure, relatively symmetrical, and easy impedance matching with the chip.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the schematic diagram of the power echo coefficient simulation result of the antenna of the present invention;

Fig. 3 is the input impedance simulation result schematic diagram of the utility model antenna;

Fig. 4 is the gain radiation pattern of the utility model antenna on the XOY surface (φ=all, θ=90°) under 915Mhz, wherein, φ represents the azimuth angle in the horizontal direction, and θ represents the pitch angle in the vertical direction;

Fig. 5 is the gain radiation pattern of tag antenna of the present invention on the XOZ surface (φ=0, θ=all) under 915Mhz;

Among them, 1-substrate, 2-antenna layer, 3-chip, 21-resonant frequency point tuning structure, 22-impedance matching tuning structure, 211-horizontal two-way folded dipole structure, 212-vertical two-way folded dipole structure, 213-first metal arm, 214-second metal arm, 215-third metal arm, 216-first arc connecting arm, 217-second arc connecting arm, 221-folding stub structure, 222-horizontal Capacitive load, 223 - vertical capacitive load.

Detailed ways

In the following, the technical solution of the utility model is described in detail through specific embodiments, and many specific details are set forth in the following description so as to fully understand the utility model. However, the utility model can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific implementation disclosed below .

As shown in Figures 1 to 5, a miniaturized high-gain UHF antenna proposed by the present invention includes a resonant frequency point tuning structure 21 and an impedance matching tuning structure 22;

The resonant frequency point tuning structure 21 includes a horizontal two-way folded dipole structure 211 and a vertical two-way folded dipole structure 212, and the impedance matching tuning structure 22 includes a folded stub structure 221 arranged on the inner layer; the folded stub Horizontally opposite sides of the line structure 221 are respectively connected to the horizontal two-way folded dipole structure 211 , and vertically opposite sides are respectively connected to the vertical two-way folded dipole structure 212 .

The resonant frequency point tuning structure 21 and the impedance matching tuning structure 22 are all located on the same square plane (the upper surface of the dielectric substrate), and the basic structure of using the horizontal bidirectional folded dipole structure 211 and the vertical bidirectional folded dipole structure 212 to load the capacitive load The miniaturization of the antenna is realized, and on this basis, the capacitive load is loaded and the matching network of the folded stub structure 221 is used to realize the higher gain, bandwidth and impedance matching characteristics of the tag antenna at UHF, which is different from The new structure of the traditional curved dipole structure effectively solves the design problems of miniaturization, high gain, and bandwidth of the tag antenna. It has the maximum gain at 915MHz and can achieve a long reading range. Therefore, the UHF antenna has a structure It is simple, relatively symmetrical, and easy to perform impedance matching with the chip 3 .

The use of the horizontal two-way folded dipole structure 211 and the vertical two-way folded dipole structure 212 will generate greater inductive coupling at a center frequency of 915Mhz, which has the largest gain and can achieve a longer reading range, thereby realizing the miniaturization of the tag antenna In addition, the horizontal bifold dipole structure 211 and the vertical bifold dipole structure 212 are both serpentine stack structures. Compared with the traditional V-shaped structure, the serpentine structure can effectively reduce the electrical length, reduce the resonance frequency without increasing the structure size, and meet the requirements of miniaturization and compact circuits.

When the antenna layer 2 cooperates with the substrate 1 and the chip 3 to form a UHF tag, both the antenna layer 2 and the chip 3 are etched on the upper surface of the substrate 1, wherein the antenna layer 2 adopts the UHF antenna of the present application, and the substrate 1 is flexible Dielectric substrate, the substrate 1 uses PET as the material of the flexible substrate, and the antenna layer 2 is covered with an aluminum film on the upper surface of the substrate PET. The thickness of the covered aluminum film antenna is set to 0.017mm, and the thickness of the PET substrate is set to 0.05mm , the relative permittivity is 3.5, the loss tangent is 0.003, the upper surface of the flexible dielectric substrate is a metal radiation antenna layer 2, the upper surface of the antenna layer 2 is connected with a chip 3, the chip 3 is electrically connected with the antenna layer 2 and arranged on The middle position of the lower part of the first metal arm 213 is used to feed power to the antenna layer 2. Therefore, the present application can not only realize the miniaturization of the electronic tag, but also maintain better gain and bandwidth while satisfying the miniaturization of the electronic tag, and Good reading distance.

In this embodiment, the impedance matching tuning structure 22 further includes a horizontal capacitive load 222 and a vertical capacitive load 223, and the horizontal capacitive load 222 is connected to the end of the horizontal bidirectional folded dipole structure 211 away from the folded stub structure 221 , the vertical capacitive load 223 is connected with the vertical two-way folded dipole structure 212 at the end away from the folded stub structure 221, the horizontal capacitive load 222 and the horizontal two-way folded dipole structure 211 form an LC resonant circuit, and the vertical capacitive load 223 and the vertical bidirectional folded dipole structure 212 form an LC resonant circuit.

Since the horizontal two-way folded dipole structure 211 and the vertical two-way folded dipole structure 212 increase the area of horizontal radiation, the horizontal two-way folded dipole structure 211 and the vertical two-way folded dipole structure 212 are placed orthogonally, horizontal The two-way folded dipole structure 211 is obtained by rotating the vertical two-way folded dipole structure 212 by 90 degrees, so that the gain of the tag antenna becomes larger,

By adjusting the length and width of the folded stub structure 221 of the inner layer, and the length and width of the horizontal capacitive load 222 and the vertical capacitive load 223, the input resistance and reactance to the antenna layer 2 can be adjusted at the same time, so that it is compatible with the chip 3 achieve good impedance matching, increase the signal transmission efficiency between the chip 3 and the antenna layer 2, and adjust the resistance and reactance to the antenna layer 2 at the same time to achieve good impedance matching. This embodiment can not only benefit the UHF antenna The miniaturization and high gain are also conducive to further matching with different RFID chips at the required frequency.

In addition, in this embodiment, the resonant frequency point tuning structure 21 further includes a first metal arm 213, a second metal arm 214 and a third metal arm 215, and the first metal arm 213 is arranged under the folded stub structure 221 for Supporting the folded stub structure 221, the two ends of the second metal arm 214 are respectively connected to the horizontal end of the first metal arm 213 and the end of the horizontal bidirectional folded dipole structure 211, and the two ends of the third metal arm 215 are respectively Connected to the vertical end of the first metal arm 213 and the end of the vertical bidirectional folded dipole structure 212, the resonant frequency point tuning structure 21 also includes a first arc-shaped connecting arm 216 and a second arc-shaped connecting arm 217, The two ends of the first arc-shaped connecting arm 216 are respectively connected with one of the first metal arms 213 near the end of the folded stub structure 221 and the end of one of the vertical two-way folded dipole structures 212, and the second arc-shaped connection The arms 217 are respectively connected to one of the first metal arms 213 near the end of the folded stub structure 221 and the end of the other vertical bidirectional folded dipole structure 212 .

Wherein, the first metal arm 213 and the second metal arm 214 are placed horizontally, the first metal arm 213, the second metal arm 214 and the third metal arm 215, the first arc connecting arm 216 and the second arc connecting arm 217, On the basis of the horizontal two-way folded dipole structure 211 and the vertical two-way folded dipole structure 212, respectively load a horizontal capacitive load 222 and a vertical capacitive load 223 to form an LC resonant circuit, which can be adjusted by adjusting the horizontal capacitive load 222 or The length, width, and cut angle of the vertical capacitive load 223 can adjust the equivalent capacitance value, and the resonance point of the antenna can be changed by using the LC resonant circuit. By adjusting the horizontal placement of the first metal arm 213 and the second metal arm 214, the first The metal arm 213, the second metal arm 214 and the third metal arm 215, the first arc-shaped connecting arm 216, the second arc-shaped connecting arm 217, the horizontal two-way folded dipole structure 211, and the vertical two-way folded dipole structure 212 The parameter can adjust the equivalent inductance value, and the resonance point of the antenna can be changed by using LC series resonance.

In this embodiment, the proposed RFID tag antenna of the horizontal bidirectional folded dipole structure 211, the vertical bidirectional folded dipole structure 212 and the folded stub structure 221 has been verified by simulation, and when the folded stub structure 221 matches The width of the structure in the network is 0.33mm, and its spacing is 0.5mm. When the width of bidirectional folded dipoles is 0.2mm, and the spacing is 0.45mm, the input impedance of the antenna is 18.5+j249Ω, which achieves a good connection with chip 3. Conjugate matching, and the maximum gain of the antenna reaches -3.2dB, and the radiation intensity reaches the maximum at this time.

As shown in Figure 2, in the present embodiment, when the chip 3 used works at 915MHz, the impedance of the chip 3 is 14-j252Ω; the -3dB power bandwidth of the chip 3 is 35MHz, within this bandwidth range, the chip 3 is fed to the antenna The energy loss of layer 2 is small; as shown in Figure 3, at 915MHz, the input impedance of antenna layer 2 is 18.5+j249Ω, which is relatively close to the real part and imaginary part of chip 3 impedance 14-j252Ω, so it shares the same value with chip 3. Yoke matching characteristics are good.

The size of the UHF antenna provided by this embodiment is limited to the size of the substrate 1. The shape of the substrate 1 is a square structure, and the size is limited to a length of 33mm. Compared with the traditional tag antenna in the past, it has a smaller size.

As shown in Figures 4 and 5, under the limited size of the antenna (length 33mm), this embodiment still has a maximum gain of -3.2dB on the XOY plane and the XOZ plane, and has good gain while meeting miniaturization , which can achieve a maximum reading distance of about 4.1m; at the same time, the gain radiation direction of the antenna on the XOY surface and XOZ surface at 915Mhz is omnidirectional, which can effectively meet the requirements of antenna wide-angle radiation and long-distance detection in complex environments.

To sum up, the present embodiment adopts the horizontal two-way folded dipole structure 211 and the vertical two-way folded dipole structure 212, the first metal arm 213, the second metal arm 214 and the third metal arm 215, and the first arc-shaped connecting arm 216. and the second arc-shaped connecting arm 217 to form a resonant frequency point tuning structure 21; by folding the stub structure 221, a horizontal capacitive load 222 and a vertical capacitive load 223, an impedance matching tuning structure 22 is formed; and the chip 3 is located at the first The metal arm 213 is in the middle of the lower part. Therefore, in this embodiment, the required antenna resonance point can be preliminarily realized by first adjusting the parameters in the resonance frequency point tuning structure 21 and providing different equivalent capacitance and inductance values; parameters, so as to increase the input resistance and reactance of the antenna at the same time, and finally achieve good impedance matching with chip 3. Therefore, the -3dB bandwidth of the proposed antenna is 35MHz; and the antenna layer 2 can still maintain a better gain and a longer reading distance under the limitation of a square substrate with a length of only 33mm.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto. The equivalent replacement or change of the new technical solution and the concept of the utility model shall be covered by the protection scope of the utility model.

Claims (9)

1. A miniaturized high-gain ultra-high frequency antenna is characterized in that, comprising a resonant frequency point tuning structure (21) and an impedance matching tuning structure (22); The resonant frequency point tuning structure (21) includes a horizontal two-way folded dipole structure (211) and a vertical two-way folded dipole structure (212), and the impedance matching tuning structure (22) includes a folded short intercept_structure(221); The horizontally opposite sides of the folded stub structure (221) are respectively connected to the horizontal two-way folded dipole structure (211), and the vertically opposite sides are respectively connected to the vertical two-way folded dipole structure (212). 2. miniaturized high-gain UHF antenna according to claim 1, is characterized in that, described impedance matching tuning structure (22) also comprises horizontal capacitive load (222) and vertical capacitive load (223), horizontal The capacitive load (222) is connected to the horizontal two-way folded dipole structure (211) at the end far away from the folded stub structure (221), and the vertical capacitive load (223) is connected to the vertical two-way folded dipole structure (212) End connections away from the folded stub structure (221). 3. The miniaturized high-gain UHF antenna according to claim 1, characterized in that, the resonant frequency point tuning structure (21) also includes a first metal arm (213), a second metal arm (214) and The third metal arm (215), the first metal arm (213) is arranged below the folded stub structure (221) for supporting the folded stub structure (221), and the two ends of the second metal arm (214) are respectively It is connected with the horizontal end of the first metal arm (213) and the end of the horizontal two-way folded dipole structure (211), and the two ends of the third metal arm (215) are respectively connected with the vertical end of the first metal arm (213). The end of the vertical two-way folded dipole structure (212) is connected. 4. The miniaturized high-gain UHF antenna according to claim 3, characterized in that, the resonant frequency point tuning structure (21) also includes a first arc connecting arm (216) and a second arc connecting arm (217), the two ends of the first arc-shaped connecting arm (216) are respectively connected with one of the first metal arms (213) near the end of the folded stub structure (221) and one of the vertical two-way folded dipole structures ( 212), the second arc-shaped connecting arm (217) is respectively connected with one of the first metal arms (213) near the end of the folded stub structure (221) and another vertical two-way folded dipole structure ( 212) end connection. 5. The miniaturized high-gain UHF antenna according to claim 3, characterized in that, the first metal arm (213) and the second metal arm (214) are placed horizontally. 6. The miniaturized high-gain UHF antenna according to any one of claims 1-5, characterized in that, the horizontal bidirectional folded dipole structure (211) and the vertical bidirectional folded dipole structure (212) are arranged orthogonally . 7. The miniaturized high-gain UHF antenna according to claim 6, characterized in that the horizontal bidirectional folded dipole structure (211) is obtained by rotating the vertical bidirectional folded dipole structure (212) by 90 degrees. 8. The miniaturized high-gain UHF antenna according to claim 7, characterized in that both the horizontal bidirectional folded dipole structure (211) and the vertical bidirectional folded dipole structure (212) are serpentine stacked structures. 9. A miniaturized high-gain UHF tag is characterized in that it comprises a substrate (1), an antenna layer (2) and a chip (3), and the antenna layer (2) and the chip (3) are all etched on the substrate ( 1) On the upper surface, the antenna layer (2) adopts the ultra-high frequency antenna according to any one of claims 1 to 8.