High-bandwidth circular polarization RFID antenna

Abstract

The utility model discloses a high bandwidth circular polarization RFID antenna comprising an antenna radiation unit, a power division phase shift feed network and a feed support structure, the antenna radiation unit comprises a first PCB board, the first PCB board is provided with four antenna wires, the power division phase shift feed network comprises a second PCB board, the second PCB board is provided with a power divider, and the power divider is provided with a feed support structure. The power divider comprises an input port and four output ports, the feed support structure comprises two third PCBs, two ends of the two third PCBs are provided with feed access branches, the feed access branches are respectively provided with a first connection point, a second connection point and a third connection point, and the first connection point, the second connection point and the third connection point are connected with the second connection point. The first connection point is electrically connected with a grounding port on the power division phase shift feed network, the second connection point is electrically connected with the output port, and the third connection point is electrically connected with a connection point on the antenna wire; the RFID antenna provided by the utility model has the characteristic of high bandwidth so as to cover a universal ultrahigh frequency radio frequency identification frequency range.

Description

Technical Field

[0001] The utility model relates to the technical field of RFID antennas, and particularly relates to a high-bandwidth circularly polarized RFID antenna. Background Art

[0002] Radio Frequency Identification (RFID) technology has been applied in many fields such as industrial manufacturing, inventory control, commodity tracking, anti-theft access control, and goods inventory. Passive Ultra-High Frequency (UHF) band RFID technology has advantages such as long reading distance and fast transmission rate, and is considered the most promising RFID technology. As an important part of the RFID system, the performance of the reader antenna often determines the performance of the entire system.

[0003] The ultra-high frequency bands authorized for RFID applications are different in different countries and regions. For example, the frequencies for ultra-high frequency RFID applications are 840.5–844.5 MHz and 920.5–924.5 MHz in China, 866–869 MHz in Europe, 902–928 MHz in North America, 852–855 MHz in Japan, 920–926 MHz in Australia, 865–867 MHz in India, and 908.5–914 MHz in South Korea.

[0004] Reader antennas with a working frequency band covering 840 MHz to 960 MHz are helpful for the configuration and cost reduction of RFID systems and have a wide application market. Therefore, a high-bandwidth circularly polarized RFID antenna is proposed. Content of the Utility Model

[0005] The purpose of the utility model is to provide a high-bandwidth circularly polarized RFID antenna, so as to solve the technical problem of the limited frequency range of existing ultra-high frequency RFID applications.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A high-bandwidth circularly polarized RFID antenna includes an antenna radiation unit, a power splitter and phase shifter feeding network, and a feeding support structure disposed between the antenna radiation unit and the power splitter and phase shifter feeding network.

[0008] The antenna radiation unit includes a first PCB board, on which four antenna traces are provided. The four antenna traces are independently arranged and are rotationally symmetric about the center.

[0009] The power splitter and phase shifter feeding network includes a second PCB board, on which a power splitter is arranged. The power splitter includes an input port and four output ports, and grounding ports corresponding to the four output ports one by one are arranged on the second PCB board.

[0010] The feeding support structure includes two third PCB boards which are arranged in a cross shape. Feeding access branches are arranged at both ends of the two third PCB boards. The feeding access branches are in an "h" shape. A first connection point and a second connection point are respectively arranged at the lower ends of the feeding access branches, and a third connection point is arranged at the upper end of the feeding access branches. The first connection point is electrically connected to the grounding port on the power splitter and phase shifter feeding network, the second connection point is electrically connected to the output port, and the third connection point is electrically connected to the connection point on the antenna trace.

[0011] As a further solution of the present utility model, the phases of the four output ports lag by 90° in sequence.

[0012] As a further solution of the present utility model, the power splitter is arranged with folded traces.

[0013] As a further solution of the present utility model, slots are opened at the bottom of one of the third PCB boards and the top of the other third PCB board, and the two third PCB boards are cross-connected by the slots in a cross shape.

[0014] As a preferred solution of the present utility model, two positioning protrusions are formed at the top of each of the two third PCB boards, and positioning holes corresponding to the positioning protrusions one by one are opened at the top of the first PCB board, and the positioning protrusions are inserted into the positioning holes.

[0015] As a preferred solution of the present utility model, the first PCB board, the second PCB board and the third PCB board are all high-frequency PCB boards with a thickness of 0.76 mm.

[0016] Compared with the prior art, a high-bandwidth circularly polarized RFID antenna provided by the present utility model has the characteristic of high bandwidth to cover the general ultra-high frequency radio frequency identification frequency range (the frequency band covers from 840 MHz to 960 MHz); the whole structure adopts a symmetrical design to ensure the consistency between antenna elements to the greatest extent, improve the circular polarization axial ratio, and can realize left-handed or right-handed circular polarization by configuring the phase difference between ports. By adjusting the power ratio of the output ends of the power splitter and phase shifter feeding network, the side lobes can also be suppressed and the detection accuracy can be improved. Description of the Drawings

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only individual cases of the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 One of the structural schematic diagrams of the embodiment of the present utility model;

[0019] Figure 2 The structural schematic diagram of the antenna radiation unit in the embodiment of the present utility model;

[0020] Figure 3 The structural schematic diagram of the power splitter and phase shifter feeding network in the embodiment of the present utility model;

[0021] Figure 4 The structural schematic diagram of the feeding support structure in the embodiment of the present utility model;

[0022] Figure 5 Another structural schematic diagram of the embodiment of the present utility model;

[0023] Figure 6 The antenna standing wave curve graph of the embodiment of the present utility model;

[0024] Figure 7 The antenna efficiency curve graph of the embodiment of the present utility model;

[0025] Figure 8 The antenna axial ratio curve graph of the embodiment of the present utility model.

[0026] Reference numerals: 1. Antenna radiation unit; 101. Antenna trace; 102. Positioning hole; 2. Power splitter and phase shifter feeding network; 201. Power splitter; 202. Input port; 203. Output port; 204. Ground port; 3. Feeding support structure; 301. PCB support circuit board; 302. Positioning protrusion; 303. Card slot; 304. First connection point; 305. Second connection point; 306. Third connection point; 307. Via hole. Detailed implementation manners

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following further details the embodiments of the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the embodiments of the present invention.

[0029] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can be the communication inside two elements; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific situations.

[0030] See Figures 1 to 8 As shown, an embodiment of the high-bandwidth circularly polarized RFID antenna of the present utility model includes an antenna radiation unit 1, a power divider and phase shifter feeding network 2, and a feeding support structure 3. The feeding support structure 3 is arranged between the antenna radiation unit 1 and the power divider and phase shifter feeding network 2.

[0031] See Figure 2 As shown, the antenna radiation unit 1 includes a first PCB board. Four antenna traces 101 are arranged on the first PCB board. The four antenna traces 101 are independently arranged and are rotationally symmetric about the center.

[0032] See Figure 3 As shown, the power divider and phase shifter feeding network 2 includes a second PCB board. A power divider 201 is arranged on the second PCB board. The power divider 201 includes an input port 202 and four output ports 203. Ground ports 204 corresponding to the four output ports 203 are arranged on the second PCB board. In the embodiment of the present utility model, the power divider 201 uses a two-stage Wilkinson power divider to divide a 50Ω input port 202 into four 50Ω output ports 203 with equal or unequal amplitudes and a phase difference of 90° in sequence. The phase difference between the output ports 203 is realized by the length of the microstrip line. The power divider 201 is arranged in a folded trace to realize the miniaturization of the antenna. Three isolation resistors arranged on the power divider 201 can absorb the reflected energy of the output ports and improve the port isolation.

[0033] See Figure 4As shown in the figure, the feeding support structure 3 includes two third PCB boards 301 which are arranged in a cross shape. Feed access stubs are disposed opposite to both ends of the two third PCB boards 301. The feed access stubs are in an h shape, and a plurality of vias 307 are provided on the h-shaped feed access stubs. The plurality of vias 307 are symmetrically distributed on the feed access stubs. A first connection point 304 and a second connection point 305 are respectively disposed at the lower ends of the feed access stubs, and a third connection point 306 is disposed at the upper end of the feed access stub. The first connection point 304 is electrically connected to the ground port 204 on the power splitting and phase shifting feeding network 2, the second connection point 305 is electrically connected to the output port 203, and the third connection point 306 is electrically connected to the connection point on the antenna trace 101. That is, each third PCB board 301 connects a pair of output ports with a phase difference of 180 degrees to a pair of antenna traces 101 on the antenna radiation unit 1. In the embodiment of the present invention, welding connections are adopted among the antenna radiation unit 1, the power splitting and phase shifting feeding network 2, and the feeding support structure 3.

[0034] The high-bandwidth circularly polarized RFID antenna of the above solution in the embodiment of the present invention has high-bandwidth characteristics to cover the general ultra-high frequency radio frequency identification frequency range (the frequency band covers from 840 MHz to 960 MHz). The entire structure adopts a symmetrical design to ensure the consistency among antenna elements to the greatest extent, improve the circular polarization axial ratio. By configuring the phase difference between ports, left-handed or right-handed circular polarization can be achieved. Adjusting the power ratio of the output ends of the power splitting and phase shifting feeding network can also suppress side lobes and improve the detection accuracy.

[0035] As Figures 6 - 8 shown, the standing wave of the high-bandwidth circularly polarized RFID antenna in the embodiment of the present invention is less than 1.5 in the frequency band of 800 MHz - 1000 MHz, which can meet the usage specifications in different regions of the world. The antenna adopts a circular polarization design, the axial ratio is less than 1.5 dB, the main lobe beam width is greater than 100°, and it supports the detection of various RFID tags placed randomly. In actual tests, the number of tags detected within 10 seconds is greater than 900, and the performance is excellent; the peak efficiency of the antenna is greater than 75%, and the maximum detection distance is greater than 15 meters, meeting the usage requirements of various scenarios.

[0036] For the convenience of assembly, slots 303 are provided at the bottom of one third PCB board 301 and the top of the other third PCB board 301. The two third PCB boards 301 are cross-connected by the slots 303. Two positioning protrusions 302 are formed on the top of each of the two third PCB boards 301, and positioning holes 102 corresponding to the positioning protrusions 302 are provided on the top of the first PCB board. The positioning protrusions 302 are inserted into the positioning holes 102.

[0037] The first PCB board, the second PCB board, and the third PCB board 301 are all set as high-frequency PCB boards with a thickness of 0.76 mm.

[0038] The basic principles of the present invention have been shown and described above. The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. The descriptions in the above embodiments and the specification only illustrate the principles of the present invention. Without departing from the scope of the present invention, any modifications, equivalent replacements, and improvements made within the spirit and scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-bandwidth circularly polarized RFID antenna, characterized in that: It comprises an antenna radiating unit (1), a power division phase shift feeding network (2) and a feeding support structure (3), wherein the feeding support structure (3) is arranged between the antenna radiating unit (1) and the power division phase shift feeding network (2); The antenna radiation unit (1) comprises a first PCB board, on which four antenna traces (101) are arranged, the four antenna traces (101) being arranged independently of each other, and the four antenna traces (101) being arranged in a central rotationally symmetrical manner; The power division phase-shift feeding network (2) comprises a second PCB board, a power divider (201) is arranged on the second PCB board, the power divider (201) comprises an input port (202) and four output ports (203), and grounding ports (204) corresponding one-to-one to the four output ports (203) are arranged on the second PCB board; The feeding support structure (3) comprises a third PCB board (301), two third PCB boards (301) are provided, the two third PCB boards (301) are arranged in a cross shape, both ends of the two third PCB boards (301) are provided with feeding access branches, the feeding access branches are arranged in an H shape, the lower ends of the feeding access branches are respectively provided with a first connection point (304) and a second connection point (305), the upper ends of the feeding access branches are provided with a third connection point (306), the first connection point (304) is electrically connected to a ground port (204) on the power division phase shift feeding network (2), the second connection point (305) is electrically connected to the output port (203), and the third connection point (306) is electrically connected to a connection point on the antenna trace (101).

2. A high-bandwidth circularly polarized RFID antenna according to claim 1, characterized in that: The phases of the four output ports lag by 90° in sequence.

3. A high-bandwidth circularly polarized RFID antenna according to claim 2, characterized in that: The power divider is arranged in a folded wiring shape.

4. The high-bandwidth circularly polarized RFID antenna according to claim 3, characterized in that: A card slot (303) is provided at the bottom of one of the third PCB boards (301) and at the top of the other third PCB board (301), and the two third PCB boards (301) are connected in a cross-shaped card slot via the card slot (303).

5. The high-bandwidth circularly polarized RFID antenna according to claim 1, characterized in that: The tops of the two third PCB boards (301) are both formed with two positioning protrusions (302), the top of the first PCB board is provided with positioning holes (102) corresponding one-to-one to the positioning protrusions (302), and the positioning protrusions (302) are inserted into the positioning holes (102).

6. A high-bandwidth circularly polarized RFID antenna according to any one of claims 1 to 5, characterized in that: The first PCB board, the second PCB board and the third PCB board (301) are all configured as high-frequency PCB boards with a thickness of 0.76 mm.

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