CN219534863U

CN219534863U - Miniaturized high-gain ultrahigh frequency antenna and tag

Info

Publication number: CN219534863U
Application number: CN202320281810.3U
Authority: CN
Inventors: 宋全军
Original assignee: Hefei Institutes of Physical Science of CAS
Current assignee: Hefei Institutes of Physical Science of CAS
Priority date: 2023-02-16
Filing date: 2023-02-16
Publication date: 2023-08-15
Anticipated expiration: 2033-02-16

Abstract

The utility model discloses a miniaturized high-gain ultrahigh frequency antenna and a tag, comprising a resonant frequency point tuning structure and an impedance matching tuning structure; the impedance matching tuning structure comprises a folding stub structure arranged on the inner layer, and the resonance frequency point tuning structure comprises a horizontal bidirectional folded dipole structure and a vertical bidirectional folded dipole structure; the horizontal opposite sides of the folding stub structure are respectively connected with the horizontal bidirectional folding dipole structure, and the vertical opposite sides of the folding stub structure are respectively connected with the vertical bidirectional folding dipole structure; the ultra-high frequency antenna is different from the traditional bent dipole structure, and can effectively solve the design problems of miniaturization, high gain, bandwidth and the like of the tag antenna under the condition of meeting the small size.

Description

Miniaturized high-gain ultrahigh frequency antenna and tag

Technical Field

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

Background

The wireless radio frequency identification (Radio Frequency Identification, RFID) is a non-contact automatic identification technology realized by radio frequency communication, non-contact bidirectional data communication is performed by a wireless radio frequency mode, and a recording medium (an electronic tag or a radio frequency card) is read and written by the wireless radio frequency mode, so that the purposes of identification and data exchange are achieved. The tag comprises an electronic tag (tag) and a reader, wherein the tag with codes and the reader are used for carrying out contactless data transmission through an antenna so as to complete an automatic identification process at a certain distance.

The RFID electronic tag comprises a tag antenna and a chip, wherein the tag antenna establishes communication with the identification system through a wireless electromagnetic wave signal, receives a command and data of the identification system, and transmits target object information stored by the electronic tag chip to the identification system, so that the storage, management and control of the target object information are realized; the RFID tag antenna is divided into a metal etching antenna, a printing antenna, a copper plating antenna and the like due to different materials and manufacturing processes; the RFID tag antenna is an important component of the RFID system and plays a key role in the process of realizing data communication, so that the antenna design is key to the application of the whole RFlD system.

The UHF-RFID tag antenna is widely applied to the fields needing to collect and interact a large amount of information, such as transportation, storage logistics, the Internet of things, animal husbandry and the like, due to the advantages of high working frequency and more data and energy interaction between the antenna and a reader-writer. And the omnidirectionality of the tag antenna provides stable guarantee for the efficiency and accuracy of a large amount of information interaction. Meanwhile, the electronic tag antenna needs to have a long reading distance and good reading effect, and the size of the electronic tag antenna needs to be large, but as the circuit integration degree is higher and higher, the packaging system and the antenna chip are gradually miniaturized, so that the designable size of the tag antenna matched with the electronic tag antenna is smaller and smaller, and therefore, the problem of how to improve the performance of the miniaturized UHF-RFID tag antenna is also concerned.

Common bent dipole tag antennas are miniaturized by conventional unidirectional bending technology, but the degree of miniaturization achieved by unidirectional folding is limited, and problems such as antenna gain and radiation efficiency reduction are caused.

Disclosure of Invention

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

The utility model provides a miniaturized high-gain ultrahigh frequency antenna, which comprises a resonant frequency point tuning structure and an impedance matching tuning structure; the impedance matching tuning structure comprises a folding stub structure arranged on the inner layer, and the resonance frequency point tuning structure comprises a horizontal bidirectional folded dipole structure and a vertical bidirectional folded dipole structure; the horizontal opposite sides of the folded stub structure are respectively connected with the horizontal bidirectional folded dipole structure, and the vertical opposite sides are respectively connected with the vertical bidirectional folded dipole structure.

Further, the impedance matching tuning structure further includes a horizontal capacitive load connected to the horizontal folded dipole structure at an end remote from the folded stub structure and a vertical capacitive load connected to the vertical folded dipole structure at an end remote from the folded stub structure.

Further, the resonant frequency point tuning structure further comprises a first metal arm, a second metal arm and a third metal arm, wherein the first metal arm is arranged below the folding stub structure and used for supporting the folding stub structure, two ends of the second metal arm are respectively connected with the horizontal end part of the first metal arm and the end part of the horizontal bidirectional folding dipole structure, two ends of the third metal arm are respectively connected with the vertical end part of the first metal arm and the end part of the vertical bidirectional folding dipole structure, and the chip is arranged on the first metal arm.

Further, the resonant frequency point tuning structure further comprises a first arc-shaped connecting arm and a second arc-shaped connecting arm, wherein two ends of the first arc-shaped connecting arm are respectively connected with one of the first metal arms at the end part close to the folding stub structure and the end part of one of the vertical double-folded dipole structures, and the second arc-shaped connecting arm is respectively connected with one of the first metal arms at the end part close to the folding stub structure and the end part of the other vertical double-folded dipole structure.

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

Further, the horizontal folded dipole structure and the vertical folded dipole structure are disposed orthogonally.

Further, the horizontal folded dipole structure is obtained by rotating the vertical folded dipole structure by 90 degrees.

Further, the horizontal and vertical folded dipole structures are each serpentine stacked structures.

Further, the miniaturized high-gain ultrahigh frequency tag comprises a substrate, an antenna layer and a chip, wherein the antenna layer and the chip are etched on the upper surface of the substrate, and the antenna layer adopts the ultrahigh frequency antenna.

The miniaturized high-gain ultrahigh frequency antenna and the tag provided by the utility model have the advantages that: the miniaturized high-gain ultrahigh frequency antenna and the tag provided by the structure realize miniaturization of the antenna by the basic structure of loading capacitive load by the horizontal bidirectional folded dipole structure and the vertical bidirectional folded dipole structure, and the needed antenna resonance point is primarily realized by firstly adjusting each parameter in the resonance frequency point tuning structure and providing different equivalent capacitance and inductance values; by adjusting each structural parameter in the impedance matching tuning structure, the input resistance and reactance of the antenna are increased at the same time, and finally, good impedance matching can be achieved with the chip, so that higher gain, bandwidth and impedance matching characteristics of the tag antenna under ultrahigh frequency are achieved.

Drawings

FIG. 1 is a schematic diagram of the structure of the present utility model;

FIG. 2 is a schematic diagram of the simulation result of the power echo coefficient of the antenna of the present utility model;

FIG. 3 is a schematic diagram of the simulation result of the input impedance of the antenna of the present utility model;

fig. 4 is a gain radiation pattern of the antenna of the present utility model on the XOY plane at 915Mhz (phi=all, θ=90°), where phi represents the azimuth angle in the horizontal direction and θ represents the pitch angle in the vertical direction;

fig. 5 is a gain radiation pattern of the tag antenna of the present utility model on the XOZ plane (phi=0, theta=all) at 915 Mhz;

the antenna comprises a 1-substrate, a 2-antenna layer, a 3-chip, a 21-resonant frequency point tuning structure, a 22-impedance matching tuning structure, a 211-horizontal bidirectional folded dipole structure, a 212-vertical bidirectional folded dipole structure, 213-first metal arms, 214-second metal arms, 215-third metal arms, 216-first arc-shaped connecting arms, 217-second arc-shaped connecting arms, 221-folding stub structures, 222-horizontal capacitive loads and 223-vertical capacitive loads.

Detailed Description

In the following detailed description of the present utility model, numerous specific details are set forth in order to provide a thorough understanding of the present utility model. The utility model may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the utility model, which is therefore not limited to the specific embodiments disclosed below.

As shown in fig. 1 to 5, the miniaturized high-gain ultrahigh frequency antenna provided by the utility model comprises a resonant frequency point tuning structure 21 and an impedance matching tuning structure 22;

the resonance frequency point tuning structure 21 comprises a horizontal bidirectional folded dipole structure 211 and a vertical bidirectional folded dipole structure 212, and the impedance matching tuning structure 22 comprises a folded stub structure 221 arranged on the inner layer; the horizontal opposite sides of the folded stub structure 221 are connected to the horizontal folded dipole structure 211, respectively, and the vertical opposite sides are connected to the vertical folded dipole structure 212, respectively.

The resonant frequency point tuning structure 21 and the impedance matching tuning structure 22 are both positioned on the same square plane (the upper surface of the dielectric substrate), the basic structure of loading capacitive load by utilizing the horizontal bidirectional folded dipole structure 211 and the vertical bidirectional folded dipole structure 212 realizes miniaturization of the antenna, the capacitive load is loaded on the basis, and the characteristics of higher gain, bandwidth and impedance matching of the tag antenna under ultrahigh frequency are realized by utilizing the folding stub structure 221 matching network.

The horizontal and vertical folded dipole structures 211 and 212 are configured to produce greater inductive coupling at a center frequency of 915Mhz, to provide maximum gain, and to provide a longer read range, thereby enabling miniaturization of the tag antenna, and the horizontal and vertical folded dipole structures 211 and 212 are configured as serpentine stacks. Compared with the traditional V-shaped structure, the serpentine structure can effectively reduce the electric length, reduce the resonant frequency under the condition of not increasing the structural size, and meet the requirements of miniaturized and compact circuits.

When the antenna layer 2, the substrate 1 and the chip 3 are matched to form an ultrahigh frequency tag, 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 ultrahigh frequency antenna, the substrate 1 is a flexible medium substrate, the substrate 1 is made of PET (polyethylene terephthalate) serving as a material of the flexible substrate, the antenna layer 2 is covered on the upper surface of the substrate PET by an aluminum film, the thickness of the covered aluminum film antenna is set to be 0.017mm, the thickness of the PET substrate is set to be 0.05mm, the relative dielectric constant of the PET substrate is 3.5, the loss tangent is 0.003, the upper surface of the flexible medium substrate is a metal radiation antenna layer 2, the chip 3 is connected with the upper surface of the antenna layer 2, and the chip 3 is electrically connected with the antenna layer 2 and is arranged in the middle position of the lower part of the first metal arm 213 so as to feed the antenna layer 2.

In this embodiment, the impedance matching tuning structure 22 further includes a horizontal capacitive load 222 and a vertical capacitive load 223, the horizontal capacitive load 222 is connected to the horizontal folded dipole structure 211 at an end far from the folded stub structure 221, the vertical capacitive load 223 is connected to the vertical folded dipole structure 212 at an end far from the folded stub structure 221, the horizontal capacitive load 222 and the horizontal folded dipole structure 211 form an LC resonant tank, and the vertical capacitive load 223 and the vertical folded dipole structure 212 form an LC resonant tank.

Since the horizontal folded dipole structure 211 and the vertical folded dipole structure 212 increase the area of horizontal radiation, and the horizontal folded dipole structure 211 and the vertical folded dipole structure 212 are disposed in quadrature, the horizontal folded dipole structure 211 is rotated by 90 degrees from the vertical folded dipole structure 212, so that the gain of the tag antenna becomes large,

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 of the antenna layer 2 can be adjusted at the same time, so that the input resistance and reactance of the antenna layer 2 can be well matched with the chip 3, the signal transmission efficiency between the chip 3 and the antenna layer 2 is increased, and the resistance and reactance of the antenna layer 2 can be adjusted at the same time, so that good impedance matching is realized.

In addition, in the present embodiment, the resonant frequency tuning structure 21 further includes a first metal arm 213, a second metal arm 214, and a third metal arm 215, where the first metal arm 213 is disposed below the folded stub structure 221 and is used for supporting the folded stub structure 221, two ends of the second metal arm 214 are respectively connected with a horizontal end of the first metal arm 213 and an end of the horizontal folded dipole structure 211, two ends of the third metal arm 215 are respectively connected with a vertical end of the first metal arm 213 and an end of the vertical folded dipole structure 212, the resonant frequency tuning structure 21 further includes a first arc-shaped connection arm 216 and a second arc-shaped connection arm 217, two ends of the first arc-shaped connection arm 216 are respectively connected with an end of one of the first metal arms 213 near the folded stub structure 221 and an end of one of the vertical folded dipole structure 212, and the second arc-shaped connection arm 217 is respectively connected with one of the first metal arms 213 near the folded stub structure 221 and an end of the other vertical folded dipole structure 212.

The first metal arm 213 and the second metal arm 214 are horizontally disposed, the first metal arm 213, the second metal arm 214, the third metal arm 215, the first arc-shaped connecting arm 216, and the second arc-shaped connecting arm 217 are respectively loaded on the basis of the horizontal folded dipole structure 211 and the vertical folded dipole structure 212 to form an LC resonant circuit, the length, the width, the cut angle, and the like of the horizontal capacitive load 222 or the vertical capacitive load 223 can be adjusted to adjust an equivalent capacitance value, the resonant point of the antenna can be changed by using the LC resonant circuit, the parameters of the first metal arm 213, the second metal arm 214, the third metal arm 215, the first arc-shaped connecting arm 216, the second arc-shaped connecting arm 217, the horizontal folded dipole structure 211, and the vertical folded dipole structure 212 can be adjusted to adjust an equivalent inductance value, and the resonant point of the antenna can be changed by using LC series resonance.

In this embodiment, the simulation verification of the RFID tag antenna of the proposed horizontal folded dipole structure 211, vertical folded dipole structure 212 and folded stub structure 221 shows that when the width of the structure in the folded stub structure 221 matching network is 0.33mm, the interval is 0.5mm, the width of the folded dipole is 0.2mm, and the interval is 0.45mm, the input impedance of the antenna is 18.5+j249 Ω, and good conjugate matching is achieved with the chip 3, and in addition, the maximum gain of the antenna reaches-3.2 dB, and the radiation intensity reaches the maximum at this time.

As shown in fig. 2, in this embodiment, when the chip 3 is operated at 915MHz, the impedance of the chip 3 is 14-j252 Ω; the-3 dB power bandwidth of the chip 3 is 35MHz, within which the energy loss fed by the chip 3 to the antenna layer 2 is small; as shown in fig. 3, at 915MHz, the input impedance of the antenna layer 2 is 18.5+j249 Ω, which is relatively close to the real and imaginary parts of the impedance 14-j252 Ω of the chip 3, and thus has good conjugate matching characteristics with the chip 3.

The size of the ultra-high frequency antenna provided by the embodiment is limited below the size of the substrate 1, the shape of the substrate 1 is a square structure, the size is limited to 33mm in length, and the ultra-high frequency antenna has smaller size compared with the traditional tag antenna.

As shown in fig. 4 and 5, under the limitation of small size of the antenna (length 33 mm), the maximum gain of-3.2 dB is still provided on the XOY plane and the XOZ plane in the embodiment, and the antenna has good gain while meeting miniaturization, and can achieve a reading distance of about 4.1m at maximum; meanwhile, the antenna has omnidirectionality in the gain radiation directions on the XOY plane and the XOZ plane under 915Mhz, and can effectively meet the requirements of wide-angle radiation and long-distance detection of the antenna in a complex environment.

In summary, the resonant frequency tuning structure 21 is formed by the horizontal dual-folded dipole structure 211, the vertical dual-folded dipole structure 212, the first metal arm 213, the second metal arm 214, the third metal arm 215, the first arc-shaped connecting arm 216, and the second arc-shaped connecting arm 217; by folding the stub structure 221, the horizontal capacitive load 222, and the vertical capacitive load 223, the impedance matching tuning structure 22 is constituted; while the chip 3 is located in the middle of the lower part of the first metal arm 213. Therefore, the present embodiment can initially implement the required antenna resonance point by adjusting each parameter in the resonance frequency point tuning structure 21 to provide different equivalent capacitance and inductance values; and then, by adjusting each structural parameter in the impedance matching tuning structure 22, the input resistance and reactance of the antenna are increased at the same time, and good impedance matching with the chip 3 can be achieved finally. Thus, the proposed antenna-3 dB bandwidth is 35MHz; and the antenna layer 2 can still maintain a good gain and a longer reading distance under the limitation of the size of a square substrate with a length of 33mm only.

The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should make equivalent substitutions or modifications according to the technical scheme of the present utility model and the inventive concept thereof, and should be covered by the scope of the present utility model.

Claims

1. A miniaturized high-gain ultra-high frequency antenna, which is characterized by comprising a resonant frequency point tuning structure (21) and an impedance matching tuning structure (22);

the resonant frequency point tuning structure (21) comprises a horizontal bidirectional folded dipole structure (211) and a vertical bidirectional folded dipole structure (212), and the impedance matching tuning structure (22) comprises a folded stub structure (221) arranged on an inner layer;

the horizontal opposite sides of the folded stub structure (221) are respectively connected with the horizontal double-direction folded dipole structure (211), and the vertical opposite sides are respectively connected with the vertical double-direction folded dipole structure (212).

2. The miniaturized high-gain uhf antenna of claim 1, wherein the impedance matching tuning structure (22) further comprises a horizontal capacitive load (222) and a vertical capacitive load (223), the horizontal capacitive load (222) being connected to the horizontal folded dipole structure (211) at an end remote from the folded stub structure (221), the vertical capacitive load (223) being connected to the vertical folded dipole structure (212) at an end remote from the folded stub structure (221).

3. The miniaturized high-gain ultra-high frequency antenna according to claim 1, wherein the resonant frequency point tuning structure (21) further comprises a first metal arm (213), a second metal arm (214) and a third metal arm (215), the first metal arm (213) is disposed below the folded stub structure (221) and is used for supporting the folded stub structure (221), two ends of the second metal arm (214) are respectively connected with a horizontal end of the first metal arm (213) and an end of the horizontal dual-folded dipole structure (211), and two ends of the third metal arm (215) are respectively connected with a vertical end of the first metal arm (213) and an end of the vertical dual-folded dipole structure (212).

4. A miniaturized high-gain uhf antenna according to claim 3, wherein the resonant frequency point tuning structure (21) further comprises a first arc-shaped connecting arm (216) and a second arc-shaped connecting arm (217), both ends of the first arc-shaped connecting arm (216) being connected to one of the first metal arms (213) near the end of the folded stub structure (221) and the end of one of the vertical folded dipole structures (212), respectively, and the second arc-shaped connecting arm (217) being connected to one of the first metal arms (213) near the end of the folded stub structure (221) and the end of the other of the vertical folded dipole structures (212), respectively.

5. A miniaturized high-gain ultra-high frequency antenna according to claim 3, characterized in that the first (213) and second (214) metal arms are placed horizontally.

6. A miniaturized high gain uhf antenna according to any of claims 1-5, wherein the horizontal folded dipole structure (211) and the vertical folded dipole structure (212) are arranged orthogonally.

7. The miniaturized high-gain uhf antenna of claim 6, wherein the horizontal folded dipole structure (211) is rotated 90 degrees from the vertical folded dipole structure (212).

8. The miniaturized high-gain uhf antenna of claim 7, wherein the horizontal folded dipole structure (211) and the vertical folded dipole structure (212) are each serpentine stacked structures.

9. A miniaturized high-gain ultrahigh frequency tag, which is characterized by comprising a substrate (1), an antenna layer (2) and a chip (3), wherein the antenna layer (2) and the chip (3) are etched on the upper surface of the substrate (1), and the ultrahigh frequency antenna as claimed in any one of claims 1 to 8 is adopted for the antenna layer (2).