CN108847522B

CN108847522B - Compact RFID antenna

Info

Publication number: CN108847522B
Application number: CN201810510961.5A
Authority: CN
Inventors: 李迎松; 董玥; 孙来军; 西尼吉维奇·耶夫基尼; 马尔达乔夫·费拉基米尔·伊万诺奇
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2018-05-25
Filing date: 2018-05-25
Publication date: 2021-09-10
Anticipated expiration: 2038-05-25
Also published as: CN108847522A

Abstract

A compact RFID antenna relates to the technical field of antennas. The antenna comprises a dielectric substrate, a full-coverage ground plane, a coaxial probe, a bent dipole radiation unit and two rectangular parasitic radiation units. The bent dipole radiation unit consists of two L-shaped radiation units and two anti-G-shaped radiation units. The design method of combining the coaxial feed, the bent radiation unit and the rectangular parasitic radiation unit and combining the direct feed and the indirect feed is adopted, so that the design of the high-performance RFID antenna is realized, the section height of the antenna is reduced, the bandwidth of the antenna is expanded, the gain of the antenna is improved, and more reliable communication guarantee is provided for the compact design of the tag antenna.

Description

Compact RFID antenna

Technical Field

The invention relates to the technical field of antennas, in particular to a compact RFID antenna.

Background

In recent years, with the increasing demand of various logistics supply chain management applications, such as identification, ticket management, contactless charging, intelligent logistics, etc., the radio frequency identification technology, namely RFID, has been intensively studied in recent years. RFID, also known as RFID, can identify a specific object and read/write related data via radio signals without the need to establish mechanical or optical contact between the identification system and the specific object. The RFID system mainly comprises three major parts: electronic tags, induction antenna and read-write response equipment. The RFID tag antenna is an important component of the RFID system and plays a key role in realizing data communication, so that the design of the RFID antenna is the key for the application of the whole RFID system. Wireless communication technology has developed rapidly and the requirements for antenna technology have become higher and higher. The tag antenna needs to be arranged in the tag, so that the problem to be solved is that the size of the tag antenna is limited. Common forms of tag antennas are primarily coil, microstrip and dipole antennas. The coil antenna is the most common tag antenna nowadays, has a mature theory and technology and is widely applied, but the coil antenna also has the defect that the coil antenna is only suitable for a short-distance RFID system within 1m and is often applied to a ticket management system, but the coil antenna is difficult to be widely applied to occasions with high frequency, large information amount and large working distance. The microstrip antenna is simple to manufacture and low in cost, but the microstrip antenna is large in size and only suitable for the RFID system with small change of the communication direction. Compared with the two tag antennas, the dipole antenna has the characteristics of high gain, simple manufacture, low cost and the like, and is often applied to a long-distance RFID system, but the dipole antenna also has the characteristic of larger size, so research on the dipole tag antenna is generally focused on the improved dipole antenna. Therefore, designing a dipole tag antenna with small size and high gain is one of the hot spots and difficulties in current research.

Hsin-Lung Su and Hongsheng Huang in 2017 design an elliptical slot RFID antenna, which consists of an elliptical monopole, and a rectangular slot is etched on an elliptical radiation unit; the antenna has good circular polarization characteristics, but at the same time, the directional pattern of the antenna is unstable and large in size. In 2017, Xiaping YU et al designed a broadband dipole RFID antenna, which consists of two circles and two rectangles, and in order to enlarge the frequency bandwidth, a bent rectangular structure is symmetrically added; the antenna has the advantages that the circular radiating element is arranged in the middle of the rectangular radiating element, so that the size of the antenna is reduced, but the structure adopting the circular patch has larger size. In 2017, Rongwei Wang et al designed a bent dipole RFID antenna, which consists of a bent dipole, and a rectangular radiation patch is arranged at the tail end of the bent dipole; the antenna adopts a bent dipole mode to increase the electrical length of the antenna and reduce the size of the antenna, but the size is still relatively large because only transverse folding is carried out. In summary, the large design size is a common problem in the research of dipole tag antennas.

Disclosure of Invention

The invention aims to solve the problem of large design size of the antenna, and compared with the prior art, the invention provides the compact RFID antenna with small size and high gain.

In order to achieve the above purpose, the present invention discloses a compact RFID antenna, which is composed of a dielectric substrate 106, a full coverage ground plane 101, a coaxial probe 102, a bent dipole radiation unit and two rectangular parasitic radiation units 104. The fully-covered ground plane 101 is connected to a dielectric substrate 106. The bent dipole radiation unit is composed of two L-shaped radiation units 1031 and two anti-G-shaped radiation units 1032, the L-shaped radiation units 1031 and the anti-G-shaped radiation units 1032 are directly connected, the rectangular parasitic radiation unit 104 is arranged between the L-shaped radiation units 1031 and the anti-G-shaped radiation units 1032, the two anti-G-shaped radiation units 1032 are directly connected and are in central symmetry with respect to the coaxial probe 102, and both the bent dipole radiation unit and the rectangular parasitic radiation unit 104 are in central symmetry with respect to the coaxial probe 102. The bent dipole radiation elements are directly fed through the coaxial line, and the two rectangular parasitic radiation elements 104 are indirectly fed through the coupling gaps between the bent dipole radiation elements. The center of the bent dipole radiating element is connected with the inner conductor of the connector through coaxial feed, and the outer conductor of the connector is connected with the full-coverage ground plane 101. The structure of the bent dipole radiating element and the rectangular parasitic radiating element 104 is printed on a dielectric substrate 106.

The bent dipole radiation element is composed of two L-shaped radiation elements and two anti-G-shaped radiation elements, which is just one embodiment of the antenna. The bent dipole radiation unit can adjust the impedance matching and the bandwidth of the designed antenna by adjusting the bent size and angle, and can adjust the polarization of the antenna at the same time, thereby realizing linear polarization and circular polarization design. By loading the rectangular parasitic radiation unit, the purposes of expanding the impedance bandwidth of the antenna and improving the gain of the antenna are achieved, and further long-distance communication is achieved. The antenna can adopt methods of adding a plurality of parasitic radiation units or performing fractal design on rectangular parasitic radiation units and the like, the bandwidth of the antenna is further expanded, the antenna can also be used for other communication requirements, and the antenna can be integrated on a mobile platform. The antenna can further expand the bandwidth of the antenna or reduce the size of the antenna by loading a short-circuit probe or a reactive element and the like.

The invention adopts the coaxial feed structure, fully utilizes the design method of limited space, reduces the size and the section of the antenna, realizes the design of a compact antenna, improves the gain of the antenna in the limited space and realizes the design of a high-gain RFID antenna.

Compared with the prior art, the invention has the beneficial effects that: the invention adopts coaxial feed and a structural design method of the bent antenna, effectively utilizes compact space, reduces the section of the antenna and realizes the design of the compact antenna. The antenna realizes the design of a high-gain antenna by loading the parasitic radiation unit in the bent dipole. Because the coaxial feed is adopted, the influence of the coaxial cable on the antenna radiation is reduced, and the parasitic radiation is lower. The invention adopts the design of combining hybrid feeding, reduces the size of the antenna, increases the flexibility of the antenna design, improves the gain of the antenna on the basis of expanding the bandwidth of the antenna by loading the parasitic radiation unit, and realizes the design of a compact, broadband and high-gain antenna. The antenna has the advantages of low profile, small size, low cost, and convenient design.

According to the invention, the design of the folded dipole radiation units and the parasitic radiation units is adopted, and the resonance frequency and the resonance bandwidth of the antenna are adjusted by adjusting the size of each radiation unit, the coupling gap between the parasitic radiation unit and the dipole radiation unit, the folding size and angle of the folded dipole radiation unit and the like, so that the antenna can achieve good matching and meet the design requirement of the RFID antenna. The compact RFID antenna has the characteristics of low section, small size, wide bandwidth and the like, can be used in equipment for ticket management, intelligent logistics and the like, and has wide application prospect.

Drawings

FIG. 1 is a top view of an antenna designed in accordance with the present invention;

FIG. 2 is a side view of an antenna designed in accordance with the present invention;

fig. 3 is a schematic diagram of an L-shaped structure of a bent dipole radiating element of an antenna designed according to the present invention;

fig. 4 is a schematic diagram of an inverted-G-shaped structure of a bent dipole radiation element of an antenna designed according to the present invention.

Detailed Description

The invention is further described with reference to the following detailed description and accompanying drawings.

With reference to fig. 1 to 4, the present invention designs a compact RFID antenna, which adopts a design method of a coaxial feed and bent dipole radiation unit, and adopts structural designs such as a loaded rectangular parasitic radiation unit, so as to implement a compact, broadband, and high-gain antenna design, and at the same time, the design of the antenna can be changed into a multiband or circularly polarized antenna according to actual design requirements.

The antenna related to the invention mainly comprises: dielectric substrate 106, all-over ground plane 101, coaxial probe 102, bent dipole radiating element and two rectangular parasitic radiating elements 104. The bent dipole radiation unit is composed of two L-shaped radiation units 1031 and two anti-G-shaped radiation units 1032, the L-shaped radiation units 1031 and the anti-G-shaped radiation units 1032 are directly connected, the rectangular parasitic radiation unit 104 is arranged between the L-shaped radiation units 1031 and the anti-G-shaped radiation units 1032, the two anti-G-shaped radiation units 1032 are directly connected and are in central symmetry with respect to the coaxial probe 102, and both the bent dipole radiation unit and the rectangular parasitic radiation unit 104 are in central symmetry with respect to the coaxial probe 102. The bent dipole radiation elements are directly fed through the coaxial line, and the two rectangular parasitic radiation elements 104 are indirectly fed through the coupling gaps between the bent dipole radiation elements.

The bent dipole radiation unit is designed through a bent structure, the transverse size of the antenna is reduced, the bent dipole radiation unit can adjust the impedance matching and the bandwidth of the designed antenna through adjusting the bent size and angle, meanwhile, the polarization of the antenna can be adjusted, and the linear polarization and circular polarization design is achieved. By adjusting the size of a coupling gap between the rectangular parasitic dipole radiation unit and the bent dipole radiation unit, the antenna can achieve good matching, has higher gain, and meets the design of a broadband high-gain RFID antenna. Meanwhile, according to different application directions, the antenna can be adjusted to be a multiband or circularly polarized antenna, and flexible design is carried out, so that the antenna has a wider application prospect.

The antenna designed by the invention adopts coaxial feed, the bent dipole radiation unit is connected with the inner conductor of the connector, and the outer conductor of the connector is connected with the full-coverage ground plane 101. The antenna is printed on a dielectric substrate 106 according to the structure shown in fig. 1, and the dimensions of the bent dipole radiation element and the rectangular parasitic radiation element 104 are adjusted, so that the antenna has the characteristics of wide band and high gain.

The impedance bandwidth and the resonant frequency of the antenna designed by the invention are determined by the size of each radiating element and the size of a coupling gap between each bent dipole radiating element and each rectangular parasitic radiating element. The rectangular parasitic radiation unit can be designed in different forms according to actual requirements and spatial positions, and flexibility of antenna design is improved.

The antenna designed by the invention is designed by adopting the bent dipole radiation units, and the section of the antenna is reduced by adopting the structural design of the two L-shaped radiation units 1031 and the two anti-G-shaped radiation units 1032. This kind of form is only an embodiment of this antenna, when actual design and application, can change the angle of buckling and the size of buckling dipole radiating element according to actual demand, adopts other structures such as C shape, J shape to carry out the flexibility design.

The antenna designed by the invention can adopt a design of loading the short-circuit probe on the bent dipole radiation unit, and further expands the bandwidth of the antenna or reduces the size of the antenna.

The antenna designed by the invention can adopt a fractal structure or a notch structure to design the rectangular parasitic radiation units, or the bandwidth of the antenna is expanded by increasing the number of the rectangular radiation units.

In summary, the antenna designed by the present invention adopts a coaxial feeding structure, the volume of the antenna is mainly reduced by bending the dipole radiation element, and the bandwidth of the antenna is expanded and the gain of the antenna is increased by adding the rectangular parasitic radiation element, so as to realize the design of a compact, broadband and high-gain RFID antenna. The rectangular dipole radiation unit is bent for multiple times, so that the size of the antenna is reduced, the transverse size of the antenna is reduced, and the miniaturization design is facilitated. The resonance frequency and the resonance bandwidth of the antenna can be controlled by adjusting the size of each radiating element and the size of a coupling gap between the rectangular parasitic radiating element and the bent dipole radiating element. According to different application scenes of the required antenna, the antenna can be changed and designed into a multiband or circularly polarized antenna, so that the flexibility of antenna design is facilitated. The invention relates to a compact RFID antenna, which adopts a coaxial feed structure and a fusion design combining a bent radiation unit and direct and indirect feed, thereby not only reducing the section of the antenna, but also expanding the bandwidth of the antenna, improving the gain of the antenna, realizing the design of the high-performance RFID antenna, and providing a more effective design method and a long-distance communication guarantee for the compact design of a tag antenna.

The invention aims to provide a compact RFID antenna, which adopts a coaxial feed structure, fully utilizes a design method of limited space, reduces the size and the section of the antenna, realizes the design of the compact antenna, improves the gain of the antenna in the limited space and realizes the design of a high-gain RFID antenna.

The purpose of the invention is realized as follows: the device comprises a dielectric substrate, a full-coverage ground plane arranged on the back of the dielectric substrate, a coaxial probe, a bent dipole radiation unit and two rectangular parasitic radiation units, wherein the bent dipole radiation unit consists of two L-shaped radiation units and two rotary G-shaped radiation units. The center of the bent dipole radiation unit is connected with the inner conductor of the connector through coaxial feed, and the outer conductor of the connector is connected with the full-coverage ground plane.

The invention also includes such structural features:

1. the bent dipole radiation units are directly connected with the coaxial feeder, and the two rectangular parasitic radiation units are indirectly fed through gap coupling.

2. The bent dipole radiation element is composed of two L-shaped radiation elements and two anti-G-shaped radiation elements (which is just one embodiment of the antenna).

3. By loading the rectangular parasitic radiation unit, the purposes of expanding the impedance bandwidth of the antenna and improving the gain of the antenna are achieved, and further long-distance communication is achieved.

4. The antenna can adopt methods of adding a plurality of parasitic radiation units or performing fractal design on rectangular parasitic radiation units and the like, the bandwidth of the antenna is further expanded, the antenna can also be used for other communication requirements, and the antenna can be integrated on a mobile platform.

5. The antenna can further expand the bandwidth of the antenna or reduce the size of the antenna by loading a short-circuit probe or a reactive element and the like.

Claims

1. A compact RFID antenna consisting of a dielectric substrate (106), a fully covered ground plane (101) and a coaxial probe (102), characterized in that: the full-coverage ground plane (101) is connected to the back surface of the dielectric substrate (106); a bent dipole radiation unit and two rectangular parasitic radiation units (104) are carved on the dielectric substrate (106); the bent dipole radiation unit consists of two L-shaped radiation units (1031) and two anti-G-shaped radiation units (1032); the whole reverse G-shaped radiation unit (1032) is composed of a right-angle trapezoid module, a right-angle triangle module, an L-shaped module and a C-shaped module; one end of the C-shaped module is free, the other end of the C-shaped module is connected with one end of the L-shaped module, the other end of the L-shaped module is connected with the bottom edge of the right-angle triangular module, and the bevel edge of the right-angle triangular module is connected with the bevel edge of the right-angle trapezoidal module; two inverted-G shaped radiating elements (1032) are connected together by the free ends of their C-shaped modules; the L-shaped radiation unit (1031) consists of a rectangular part and a right-angled trapezoid part; the rectangular part of the L-shaped radiating unit (1031) is connected with the right trapezoid module of the anti-G-shaped radiating unit (1032) through the right-angled triangular radiating unit, the right-angled side of the right-angled triangular radiating unit is connected with the rectangular part of the L-shaped radiating unit (1031), and the hypotenuse of the right-angled triangular radiating unit is connected with the upper bottom edge of the right trapezoid module of the anti-G-shaped radiating unit (1032); the rectangular parasitic radiation unit (104) is engraved between the L-shaped radiation unit (1031) and the anti-G-shaped radiation unit (1032); the coaxial probe (102) is arranged at the free end connection position of the C-shaped modules of the two anti-G-shaped radiating units (1032), the two anti-G-shaped radiating units (1032) are in central symmetry with respect to the coaxial probe (102), the two rectangular parasitic radiating units (104) are in central symmetry with respect to the coaxial probe (102), and the whole bent dipole radiating unit is in central symmetry with respect to the coaxial probe (102); the bent dipole radiation unit is directly fed through the coaxial probe (102), and the two rectangular parasitic radiation units (104) are indirectly fed through coupling gaps between the two rectangular parasitic radiation units and the bent dipole radiation unit.

2. A compact RFID antenna as recited in claim 1, wherein: the rectangular parasitic radiation unit (104) is designed by adopting a fractal structure or a notch structure.