CN216818618U - Broadband radio frequency identification reader antenna - Google Patents

Abstract

The application provides a broadband radio frequency identification reader antenna which is applied to an asset management scene. The broadband radio frequency identification reader antenna comprises: radiation substrate and feed substrate, radiation substrate and feed substrate configuration relatively, the feed substrate side of keeping away from of radiation substrate disposes the radiating element, the radiating element includes main radiation piece and parasitic branch node, evenly spaced disposes branch node on the main radiation piece, the outside of branch node disposes rather than the shape matching parasitic branch node, branch node be used for with parasitic branch node coupling, the feed substrate have first side, its with radiation substrate configuration relatively, dispose the feed network on the first side, and with the relative second side in first side, dispose the reflecting plate on the second side, the main radiation piece passes through the feed network that first connecting piece connects the feed substrate. Through the design, the miniaturized broadband RF I D reader antenna is realized.

Description

A broadband radio frequency identification reader antenna

technical field

The present application relates to the field of wireless communication, and in particular, to a broadband radio frequency identification reader antenna applied in an asset management scenario.

Background technique

At present, the research on reader antennas is increasing with the increase in the demand for radio frequency systems, and the technical requirements for reader antennas are also different in different applications. For applications with limited space such as smart tool cabinets, The requirement of the antenna is to reduce the size of the antenna without changing or improving the performance of the original antenna, thereby increasing the utilization rate of the equipment space. Therefore, miniaturization has become one of the mainstream of antenna design.

In recent years, scholars at home and abroad have been continuously researching miniaturized reader antennas. For example, in the literature [Fan Guanping, Zhang Guanmao, Qiao Litao, et al. Design of UHF RFID reader antenna based on fractal structure [J]. Wireless Communication, 2019, 9(1):9], an antenna based on Minkowski and Koch was proposed. A fractal structure can effectively reduce the size of the antenna, but the design of the fractal structure is relatively complex, and the realized bandwidth is relatively narrow; the literature [Mei S, Ping Z Y.A chipantenna in LTCC for UWB radios[J].IEEE Transactions on Antennas & Propagation, 2008, 56(4): 1177-1180] used low temperature co-fired ceramic (LTCC) technology with relatively high dielectric constant to design a miniaturized ultra-wideband chip antenna with an operating frequency band of 3.75-10.45GHz. However, the gain of the antenna is relatively low, and the peak gain is only 2.3dBic; meander technology is also usually used in the miniaturization of the antenna, such as the literature [Gmih Y, Hachimi Y E, Makroum E M, et al. A small printed antenna with circular slot for European UHFRFID reader devices[C]//2018:1-5] One L-shaped slot and three rectangular slots are opened on the circular conductor patch, which changes the current direction of the antenna during resonance, thereby reducing the size, but the relative bandwidth of the antenna is only 6.8%, and the peak gain is only 2.91dBic; in addition, the loading technology is also one of the important research directions of antenna miniaturization, literature [ShenZ, Wang J.Top-Hat Monopole Antenna For Conical-Beam Radiation[J].IEEE Antennas and Wireless Propagation Letters, 2011, 10:396-398], the cylindrical monopole antenna uses a metal disc for top loading, thereby significantly reducing the height of the metal column, The miniaturization of the monopole antenna is realized, but the top loading method only reduces the section height of the antenna, and the actual size of the antenna is not effectively reduced.

To this end, existing reader antennas need to be improved.

Utility model content

In order to overcome the above-mentioned defects, the purpose of this application is to propose a miniaturized broadband radio frequency identification reader antenna for the application scenario of the intelligent tool management cabinet, which is realized by combining short-circuit loading, meandering and other technologies. A miniaturized and broadband RFID reader antenna has been developed.

To achieve the above object, the application adopts the following technical solutions,

A broadband radio frequency identification reader antenna, characterized in that it includes:

Radiating substrate and feeding substrate,

The radiating substrate and the feeding substrate are arranged opposite to each other,

A radiation unit is arranged on the side of the radiation substrate away from the feeding substrate,

The radiating unit includes a main radiating sheet and a parasitic branch,

The main radiating sheet is evenly spaced with branches, the outer side of the branch is configured with the parasitic branch whose shape matches, and the branch is used for coupling with the parasitic branch,

The feeding substrate has a first side disposed opposite the radiating substrate on which a feeding network is disposed, and a second side opposite the first side, on the second side Equipped with a reflector,

The main radiating sheet is connected to the feeding network of the feeding substrate through the first connecting piece. Through this design, parasitic branches are arranged at the corners of the radiation unit of the reader antenna, and the coupling between the parasitic branches and the main radiating patch forms a series LC circuit, which increases the introduced capacitance and inductance value and reduces the reader antenna. the resonant frequency, and then reduce the size of the antenna.

Preferably, the radiation substrate is in a square shape, and the main radiation sheet includes:

A circular patch, four branches are arranged at uniform intervals in the circumferential direction of the circular patch, and the four branches are arranged at the corners of the radiation substrate, and the outer sides of the branches are arranged with the branches Shape-matched parasitic nodules.

Preferably, the branch is in the shape of an arrow.

Preferably, the branch is designed integrally with the circular patch.

Preferably, an orthogonal rectangular slot is arranged in the center of the main radiating sheet. By introducing a pair of orthogonal rectangular slots in the center of the main radiating patch, using meandering technology, the current path is extended, the resonance frequency is reduced, and the miniaturization of the reader antenna is further realized.

Preferably, the branch is located on the centerline of the orthogonal rectangular groove.

Preferably, the parasitic branches are respectively connected to the reflector through second connectors.

Preferably, the end of the parasitic branch is provided with a connecting end, and the second copper column is connected to the reflector through the connecting end.

Preferably, the ratio of the area S1 of the reflector to the area S2 of the radiation substrate is between 1.2 and 1.5.

Preferably, the ratio of the area S3 of the feeding substrate to the area S2 of the radiation substrate is between 0.4 and 0.8.

beneficial effect

Compared with the prior art, the reader antenna proposed in this application can realize the detection of linearly polarized tags in any direction; it has a narrow scanning beam and high far-field gain, and has good directivity, not only It can avoid misreading labels outside the limited area, and can also detect labels at a longer distance within the scanning range; the antenna has the advantages of simple and miniaturized structure, wear resistance, etc., and is easy to install.

Description of drawings

1a is a schematic top view of a reader antenna according to an embodiment of the present application,

FIG. 1b is a schematic cross-sectional view of a reader antenna according to an embodiment of the application,

FIG. 2 is a schematic structural diagram of a feeding network according to an embodiment of the application,

3 is a schematic diagram of a 90° power division phase shift circuit according to an embodiment of the application,

4 is a schematic diagram of an antenna return loss simulation and an actual measurement result according to an embodiment of the application,

FIG. 5 is a schematic diagram of the simulation and actual measurement results of antenna gain and axial ratio according to an embodiment of the application,

Figures 6a and 6b are the two-dimensional far-field simulation and measured pattern of the xoz plane and the yoz plane of the antenna at 915MHz, respectively.

Detailed ways

The above scheme will be further described below in conjunction with specific embodiments. It should be understood that these examples are intended to illustrate the present application and not to limit the scope of the present application. The implementation conditions used in the examples can be further adjusted such as the conditions of specific manufacturers, and the implementation conditions that are not specified are usually the conditions in routine experiments.

The present application provides a broadband radio frequency identification reader antenna (hereinafter referred to as the reader antenna),

The reader antenna includes:

A single-sided radiating substrate and a feeding substrate, wherein the single-sided radiating substrate and the feeding substrate are arranged opposite to each other, and are connected by a first connecting member.

The side of the radiation substrate away from the feeder substrate is the top surface of the radiation substrate, the middle part of the top surface is configured with a circular radiating sheet, the main radiating sheet is evenly spaced in the circumferential direction with support nodes, and the top surface is also configured with Parasitic stubs with matching stub shapes, and the parasitic stubs are located on the outside of the stubs. A pair of orthogonal rectangular slots are introduced into the center of the circular patch. For the main radiating sheet, preferably, the branches are located at the corners of the radiating substrate. Further, the branch section and the main radiator are integrally designed. The parasitic branches are respectively connected to the reflecting plates through the second connecting pieces, and the reflecting plates are arranged on the side of the feeding substrate away from the radiation substrate. In this embodiment, the feeding substrate has a first side, which is arranged on the opposite side of the radiation substrate, the feeding network is arranged on the first side, and the reflecting plate is arranged on the second side opposite to the first side. In this embodiment, a space is provided between the single-sided radiation substrate and the power feeding substrate. The radiating substrate, the feeding substrate and the reflecting plate are all square. In this embodiment, the area of the radiation substrate is larger than that of the feeding substrate and smaller than that of the reflection plate. By introducing a rectangular slot to extend the current path and reduce the antenna resonance point. Preferably, the ratio of the area S1 of the reflector to the area S2 of the radiation substrate is between 1.2 and 1.5. The ratio of the area S3 of the feeding substrate to the area S2 of the radiation substrate is between 0.4 and 0.8. At the four corners of the antenna radiating element, four grounded parasitic branches are loaded, and a series LC circuit is formed through the coupling with the main radiating patch, which increases the introduced capacitance and inductance value, reduces the resonant frequency of the antenna, and then Reduce the size of the antenna to return it to the working frequency, and finally introduce a pair of orthogonal rectangular slots in the center of the main radiating patch, and use the meandering technology to extend the current path, reduce the resonant frequency, and further realize the miniaturization of the antenna. The design of the feeding network is composed of a 90° power division phase-shifting network built with lumped elements and a microstrip line with a length of λ/4, so that the power amplitudes between the four feeding ports are equal, and the phases differ by 90° in turn. , thus achieving circular polarization.

Next, the reader antenna of the present application will be described with reference to the accompanying drawings.

As shown in Figures 1a/1b, 1a is a schematic top view of a reader antenna according to an embodiment of the present application, and Figure 1b is a schematic cross-sectional view of a reader antenna according to an embodiment of the present application. The broadband radio frequency identification reader antenna (also called UHF RFID reader antenna), which is used in smart tool management cabinets.

The reader antenna includes: a radiating substrate 100 and a feeding substrate 200, both of which are configured in a square (eg, square)

The radiation substrate 100 is disposed opposite to the feeding substrate 200 and is connected by a plurality of first copper pillars 310 .

The side of the radiation substrate 100 away from the feeding substrate is the top surface of the radiation substrate, and a circular radiation patch (also called a circular patch) 110 is arranged in the middle of the top surface, and the circular patches 110 are evenly spaced in the circumferential direction There are four branches 120 in the configuration, and the outside of the branch is also configured with a parasitic branch 140 whose shape matches. A pair of orthogonal rectangular slots 130 are arranged in the center of the circular patch, and the rectangular slots are used to extend the current path and reduce the resonance point of the antenna. Preferably, the branch 120 is located on the centerline of the orthogonal rectangular slot 130 . In one embodiment, the center line of the rectangular slot coincides with the diagonal line of the radiation substrate. In one embodiment, the branch is arrow-shaped; the shape of the parasitic branch matches (same) the shape of the branch. There is a gap G1 between the parasitic branch and the branch. The end of the parasitic branch is configured with a connection end 141 , and the second copper pillar 320 is connected to the reflector 210 through the connection end 141 . The reflector 210 is disposed on the side of the feeding substrate 200 away from the radiation substrate. The connection end is arranged on the diagonal line of the radiation substrate or the center line (or the extension line of the center line) of the orthogonal rectangular slot. In one embodiment, the branch 120 and the main radiating sheet 110 are integrally designed. The parasitic branches 140 are respectively connected to the reflecting plates 210 through the second connecting members 320 , and the reflecting plates 210 are disposed on the side of the feeding substrate 200 away from the radiation substrate. In this embodiment, the feeding substrate has a first side, which is disposed on the opposite side of the radiation substrate, the first side is provided with the feeding network 220 , and the reflecting plate 210 is disposed on the second side opposite to the first side. Preferably, the feeding substrate 200 and the reflecting plate 210 are all square. In this embodiment, the area of the radiation substrate 100 is larger than that of the feeding substrate and smaller than that of the reflector. Preferably, the ratio of the area S1 of the reflector to the area S2 of the radiation substrate is between 1.2 and 1.5. The ratio of the area S3 of the feeding substrate to the area S2 of the radiation substrate is between 0.4 and 0.8. The circular patch is provided with a connecting portion, and the first copper column is connected to the feeding substrate (the feeding network on the feeding substrate) through the connecting portion. The circular patch is a metal layer printed on the radiating substrate.

In this embodiment, the radiation substrate 100 adopts a single-sided FR4 radiation substrate with a thickness of 0.8 mm, and a "snowflake"-shaped main radiation patch is arranged on the top surface of the radiation substrate: the main radiation patch includes: a circular patch 110 and a The branches 120 in the circumferential direction of the circular patch (the branches are in the shape of “arrows”) are provided with parasitic branches 140 whose shapes match the outside of the branches (the branches 120 and 140 are capacitively coupled). The thickness of the feeding substrate is 1 mm, and the feeding substrate 200 and the radiation substrate 100 are connected by four first copper pillars 310 . The feeding substrate 200 has a first side, which is disposed opposite to the radiation substrate, on which the feeding network 220 is disposed, and a second side, opposite to the first side, on which a reflecting plate is disposed. The specific parameters of the antenna in this embodiment are as follows:

Gnd_xy＝150mm, Pxy＝98mm, L1＝14mm, L2＝7.5mm, L3＝5.4mm, L4＝14.8mm, L5＝3mm, L6＝22.5mm, L7＝18.9mm, L8＝9.7mm, L9＝7.3mm , L10=19.5mm, W1=3mm, W2=1.8mm, R1=48mm, Gap_L=80mm, Gap_w=2mm, H1=0.8mm, H2=23.5mm, H3=1mm, H4=1mm.

The feeder network is composed of three identical 90° power division and phase-shifting networks (shown in the box in Figure 2). The corresponding feeder network structure diagram and 90° power division and phase-shifting network are shown in Figure 2. The topology of the feeder network 220 is shown in Figure 2. As shown, port1/port2/port3/port4 are connected to the circular patch through first copper pillars (not shown), respectively. Figure 2 includes three 90° power division phase shifting networks A. The topology of the 90° power division phase-shifting network A is shown in Figure 3. 3 includes a first inductor L1, a second inductor L2, a third inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a resistor R1,

Wherein, the first end of the first inductor L1 is connected to the first end of the third capacitor C3 and the input port input port,

The second end of the first inductor L1 is connected to the first end of the first capacitor C1 and port2, the second end of the first capacitor C1 is connected to the first end of the second capacitor C2 and the first end of the second inductor L2, and the second capacitor The second end of C2 is connected to port1 and the first end of the third inductor L3, the second end of the third inductor L3 is connected to the second end of the fourth capacitor C4 and one end of the resistor R1, the other end of the resistor R1 is electrically grounded, the first The second end of the two inductors L2 is connected to the second end of the third capacitor C3 and the first end of the fourth capacitor C4. In this embodiment, the inductance values of the first inductance L1 to the third inductance L3 are the same, and 8.7nF is selected, and the capacitances of the first capacitor C1 to the fourth capacitor C4 are the same and 3.3pF. Resistor R1 selects 50 ohms. In one embodiment, referring to FIG. 3 in combination with FIG. 2 , PortA and PortB are respectively connected to Port1 and Port2, and PortIn is connected to the input side.

The reader antenna works as follows:

Three 90° power division phase-shifting networks built with lumped elements and a microstrip line with a length of λ/4 are designed to design a 4-port feed with a phase difference of 90° in turn, and the power of each feed port is equal The network has reached the conditions for realizing circular polarization. Then the first copper column is used to send the signal into the radiating unit of the antenna. The radiating unit includes a main radiating sheet and parasitic branches, such as four parasitic branches, and the four parasitic branches are configured for short-circuit loading.

通过增大电容电感的值。也就是阅读器天线中的寄生支节的尺寸以及寄生支节与主辐射片之间的距离，即可以降低阅读器天线的谐振频率，然后通过缩小阅读器天线的尺寸使之回到相应的工作频率，从而达到天线小型化的目的，之后是在主辐射片的中心引入一对正交的矩形槽，延长阅读器天线的电流路径，进一步对阅读器天线进行小型化处理。Since the four parasitic branches are grounded (connected to the reflector), they are inductive, and there is coupling between the parasitic branch and the main radiation patch, so there will be coupling capacitances, which are equivalent to the four The corners respectively introduce a series LC circuit whose resonant frequency is

By increasing the value of the capacitor inductance. That is, the size of the parasitic branch in the reader antenna and the distance between the parasitic branch and the main radiator, that is, the resonant frequency of the reader antenna can be reduced, and then the size of the reader antenna can be reduced to return to the corresponding work. In order to achieve the purpose of miniaturization of the antenna, a pair of orthogonal rectangular slots are introduced in the center of the main radiator to extend the current path of the reader antenna and further miniaturize the reader antenna.

Figure 4 shows the simulation and measurement results of the reader antenna return loss. Taking -10dB as the standard, whether it is the simulation or measurement results, the reader antenna in the frequency band of 800-1000MMz, its S11 value is below -10dB, not only covering It covers the RFID frequency band in China, and also covers the RFID frequency band in the United States.

Figure 5 shows the simulation and measurement results of the far-field gain and axial ratio of the reader antenna. It can be seen from the figure that the axial ratio of the antenna in the frequency band of 800-1000MHz is below 3dB, indicating the circular polarization of the reader antenna. The performance is very good, and the peak gain can reach 6dBic.

Figure 6a shows the 2D pattern of the reader antenna on the xoz plane at 915MHz, and Figure 6b shows the 2D pattern of the reader antenna on the yoz plane at 915MHz. From Figures 6a and 6b, it can be seen that the The backlobe and sidelobe gains are relatively low.

The above-mentioned embodiments are only intended to illustrate the technical concept and characteristics of the present application, and the purpose thereof is to enable those who are familiar with the technology to understand the content of the present application and implement them accordingly, and cannot limit the protection scope of the present application. All equivalent transformations or modifications made in accordance with the spirit and spirit of this application shall be covered within the protection scope of this application.

Claims (10)

1. A wideband radio frequency identification reader antenna, comprising:

a radiation substrate and a feed substrate,

the radiating substrate is arranged opposite to the feed substrate,

the side of the radiating substrate far away from the feeding substrate is provided with a radiating element,

the radiating unit comprises a main radiating sheet and a parasitic branch section,

branch sections are uniformly arranged on the main radiating sheet at intervals, the parasitic branch sections matched with the branch sections in shape are arranged on the outer sides of the branch sections, the branch sections are used for being coupled with the parasitic branch sections,

the feed substrate has a first side disposed opposite the radiating substrate, the first side having a feed network disposed thereon, and a second side opposite the first side, the second side having a reflector disposed thereon,

the main radiating plate is connected with a feed network of the feed substrate through a first connecting piece.

2. The wideband radio frequency identification reader antenna of claim 1,

the radiation substrate is the square, main radiation piece includes:

the patch comprises a circular patch, wherein 4 branch nodes are uniformly arranged at intervals in the circumferential direction of the circular patch, the branch nodes are arranged at the corner of the radiation substrate, and parasitic branch nodes matched with the branch nodes in shape are arranged on the outer side of each branch node.

3. The wideband radio frequency identification reader antenna according to claim 2 wherein said stub is arrow shaped.

4. The wideband radio frequency identification reader antenna according to claim 2 wherein said stubs are integrally designed with a circular patch.

5. The wideband radio frequency identification reader antenna of claim 1,

and the center of the main radiating fin is provided with an orthogonal rectangular groove.

6. The wideband radio frequency identification reader antenna according to claim 5,

the branch sections are located on the center line of the orthogonal rectangular groove.

7. The wideband radio frequency identification reader antenna of claim 1,

the parasitic branch sections are connected with the reflecting plate through second connecting pieces respectively.

8. The wideband radio frequency identification reader antenna of claim 7,

the tip of parasitic branch festival disposes the link, and the second copper post passes through the link is connected to the reflecting plate.

9. The wideband radio frequency identification reader antenna according to claim 1,

the ratio of the area S1 of the reflecting plate to the area S2 of the radiating substrate is 1.2-1.5.

10. The wideband radio frequency identification reader antenna according to claim 1,

the ratio of the area S3 of the feed substrate to the area S2 of the radiating substrate is 0.4-0.8.

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