Ultrahigh frequency RFID identification system

Abstract

The utility model discloses an ultrahigh frequency RFID identification system, comprising a planar antenna array, a power division phase shift network and an ultrahigh frequency reader-writer module, the planar antenna array comprises a plurality of ultrahigh frequency antenna groups, and the plurality of ultrahigh frequency antenna groups are placed in a coplanar manner; and the power division phase shift network is respectively connected with the ultrahigh frequency antenna group and the ultrahigh frequency reader-writer module. The ultrahigh frequency antenna group comprises a plurality of linearly arranged antenna array elements and an independent feed structure, and the feed power ratio is 1: 1-8: 1. The planar antenna array is adopted to replace a traditional single-antenna system or a multi-antenna system, accurate control over the radiation boundary of the ultrahigh-frequency RFID recognition system and beam scanning in the specific direction are achieved through distribution of the feed amplitude and phase of the planar antenna array, and therefore the probability of serial reading and missed reading is reduced, and robustness in the RFID recognition process is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to radio frequency identification technical field, concretely relates to a kind of ultra-high frequency RFID identification system. BACKGROUND

[0002] According to the electromagnetic wave of data exchange between RFID system reader and tag, the working frequency of RFID system can be divided into low frequency (LF, 30~300KHz, typical frequency is 125KHz, 134.2KHz), high frequency (HF, 3~30MHz, typical frequency is 1.56MHz), ultra-high frequency (UHF, 300~968MHz, typical frequency 869.5MHz, 915.3MHz), microwave (MW, 2.45~5.8GHz, typical frequency is 2.45GHz) four frequency bands.According to different working frequency, in passive case, its technical characteristics and application specification are different.UHF frequency band has the advantages of long read-write distance, fast multi-tag identification speed, strong anti-interference ability and small tag volume, large capacity, and UHF frequency band RFID technology and its related standard protocol have become the focus of global RFID industry and research department.

[0003] No doubt, with the rise of Internet of Things, RFID, as an automatic identification technology, has broad development space and bright prospects.However, due to the characteristics of RFID communication, affected by working environment, identification target movement, antenna direction sensitivity, etc., RFID tag is easy to miss reading and read in series, which greatly reduces the performance of RFID system in practical application.In order to alleviate the influence of the above factors, RFID system with specific spatial beam scanning capability is an excellent solution.

[0004] Therefore, it is necessary to provide an ultra-high frequency RFID identification system, which improves the robustness of RFID identification by controlling the direction and coverage range of antenna beam. UTILITY MODEL CONTENT

[0005] The technical problem to be solved by the utility model is to provide an ultra-high frequency RFID identification system, which improves the robustness of RFID identification by controlling the direction and coverage range of antenna beam.

[0006] In order to solve the above technical problems, the utility model adopts the technical scheme of: the ultra-high frequency RFID identification system, including planar antenna array, power division phase shift network and ultra-high frequency reader module, the planar antenna array includes a plurality of ultra-high frequency antenna groups, and a plurality of the ultra-high frequency antenna groups are placed in the same plane;The power division phase shift network is respectively connected with the ultra-high frequency antenna group and the ultra-high frequency reader module.

[0007] The technical scheme is adopted, multiple ultra-high frequency antenna groups are co-planarly placed to form a planar antenna array, the ultra-high frequency antenna groups are used for radiating ultra-high frequency signals in a specific space; a power division and phase shift network is used for changing the amplitude and phase of the signals of the ultra-high frequency antenna groups, so as to realize automatic scanning of the antenna beam in the specific space; the ultra-high frequency reader-writer module is used for modulating and transmitting the ultra-high frequency signals, demodulating and receiving the signals, and phase control of the power division and phase shift network; the planar antenna array is used to replace a traditional single antenna system or a multiple antenna system, the amplitude and phase of the planar antenna array are distributed, the accurate control of the radiation boundary of the ultra-high frequency RFID identification system and the beam scanning in a specific direction are realized, so as to reduce the probability of string reading and missing reading, and improve the robustness in the RFID identification process.

[0008] Preferably, the ultra-high frequency antenna group comprises multiple linearly arranged antenna elements and independent feeding structures, and the feeding power ratio is 1:1-8:1.

[0009] Preferably, the power division and phase shift network comprises a power division network and a phase shift network, the power division network is connected with the phase shift network and the ultra-high frequency antenna group respectively; and the phase shift network is connected with the ultra-high frequency antenna group.

[0010] Preferably, the planar antenna array comprises three ultra-high frequency antenna groups, namely a first ultra-high frequency antenna group, a second ultra-high frequency antenna group and a third ultra-high frequency antenna group, and the power division and phase shift network is connected with the first ultra-high frequency antenna group, the second ultra-high frequency antenna group and the third ultra-high frequency antenna group respectively.

[0011] Preferably, the first ultra-high frequency antenna group, the second ultra-high frequency antenna group and the third ultra-high frequency antenna group are co-planarly placed to form a 9-element planar antenna array with 3x3. By forming 9 elements and different feeding powers of the first ultra-high frequency antenna group, the second ultra-high frequency antenna group and the third ultra-high frequency antenna group, the antenna array side lobe can be reduced, the space outside the main radiation area is rapidly reduced, and the probability of string reading is reduced. At the same time, the 9-element planar antenna array formed by the first ultra-high frequency antenna group, the second ultra-high frequency antenna group and the third ultra-high frequency antenna group compresses the beam width in two orthogonal directions in the horizontal plane, improves the gain of the main radiation direction of the antenna and the effective aperture of the antenna, and further enhances the identification ability of the system.

[0012] Preferably, the power division network comprises a power division input branch and multiple power division output branches, the power division input branch is connected with the multiple power division output branches respectively, the power division output branches are connected with the ultra-high frequency antenna groups and the phase shift network respectively; the phase shift network comprises a phase shift branch and a control port, the control port is connected with the phase shift branch; and the ultra-high frequency reader-writer module is connected with the power division input branch and the control port.

[0013] Preferably, the ultra-high frequency RFID reader module inputs the ultra-high frequency RFID signal through the power division input branch of the power division phase shift network, and the input RFID signal is equally divided into three output paths through the output branch of the power division network; correspondingly, the output branch includes a first power division output branch, a second power division output branch and a third power division output branch, and the power distribution ratio of the first, second and third power division output branches is 1:1:1.

[0014] Preferably, the phase shift branch includes a first phase shift branch and a second phase shift branch, the second power division output branch is connected to the second ultra-high frequency antenna group after phase shift through the first phase shift branch, and the signal phase lags / leads the reference phase by an integer multiple of 22.5°; the third power division output branch is connected to the third ultra-high frequency antenna group after phase shift through the second phase shift branch, and the signal phase lags / leads the reference phase by an integer multiple of 45°; the first power division output branch is connected to the first ultra-high frequency antenna group, and the output signal phase is the reference phase. The ultra-high frequency RFID reader module inputs the ultra-high frequency RFID signal through the power division input branch of the power division phase shift network, and the input RFID signal is equally divided into three output paths through the power division network, the first power division output branch is connected to the first ultra-high frequency antenna group, the second power division output branch is connected to the second ultra-high frequency antenna group after phase shift through the first phase shift branch, and the third power division output branch is connected to the third ultra-high frequency antenna group after phase shift through the second phase shift branch. By setting the phase lag or lead angle of the first phase shift branch and the second phase shift branch of the power division phase shift network, the automatic scanning of the antenna array in a specific direction can be realized, the ability of the ultra-high frequency RFID system to identify moving targets is improved, and the occurrence of missed reading is reduced.

[0015] Preferably, the feed power ratio of the first ultra-high frequency antenna group and the third ultra-high frequency antenna group is 1:1:1, and the feed power ratio of the second ultra-high frequency antenna group is 1:8:1.

[0016] Preferably, the first phase shift branch and the second phase shift branch each consist of four high-low PIN diode phase shift units to form a 4-bit digital phase shift network, and the phase shift resolution is 22.5°. The high-low PIN diode phase shift network refers to an electrical network containing a high-pass filter branch and a low-pass filter branch of a PIN diode, the high-pass filter branch has a phase lead characteristic, and the low-pass filter branch has a phase lag characteristic. By controlling the on-off of the PIN diode, the signal selects the high-pass branch or the low-pass branch to achieve the desired phase lag or lead. The 4-bit digital circuit has four high-low filter units, which are controlled by four-bit digital signals, so the phase shift resolution of the phase shift network is 3600 / 24, i.e. 22.5°, and the phase shift range is -180°-180°. A negative phase shift angle indicates a phase lag, and a positive phase shift angle indicates a phase lead.

[0017] Compared with the prior art, the utility model has the beneficial effects that: adopt plane antenna array to replace traditional single antenna system or multi antenna system, realize the accurate control of the radiation boundary of the ultra high frequency RFID identification system and the beam scanning of specific direction through the distribution of the plane antenna array feed amplitude and phase, thereby reduce the probability of the string read, the leak read, improve the robustness in the RFID identification process. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the overall composition block diagram of the suspended ultra high frequency RFID system of the utility model's ultra high frequency RFID identification system;

[0019] Figure 2 It is the first ultra high frequency antenna group composition block diagram of the utility model's ultra high frequency RFID identification system;

[0020] Figure 3 It is the plane array antenna element composition topology schematic drawing of the utility model's ultra high frequency RFID identification system;

[0021] Figure 4 It is the power division phase shift network composition block diagram of the utility model's ultra high frequency RFID identification system;

[0022] Figure 5 It is the phase shift branch composition block diagram of the utility model's ultra high frequency RFID identification system;

[0023] Figure 6 It is the phase shift branch unit principle diagram of the utility model's ultra high frequency RFID identification system;

[0024] Figure 7 It is the ultra high frequency RFID identification system beam scanning schematic drawing of the utility model's ultra high frequency RFID identification system;

[0025] Wherein: 1-plane antenna array, 101-first ultra high frequency antenna group, 1011-first ultra high frequency antenna group array element one, 1012-first ultra high frequency antenna group array element two, 1013-first ultra high frequency antenna group array element three, 1014-first ultra high frequency antenna group feed structure, 102-second ultra high frequency antenna group, 103-third ultra high frequency antenna group, 2-power division phase shift network, 201-power division network, 2011-power division input branch, 2012-first power division output branch, 2013-second power division output branch, 2014-third power division output branch, 202-phase shift network, 2021-first phase shift branch, 20211-first phase shift branch high low pass PIN phase shift unit one, 2022-second phase shift branch, 2023-control port, 3-ultra high frequency read write ware module. DETAILED DESCRIPTION

[0026] The embodiments of the utility model will be described below in detail with reference to the drawings, and the following embodiments are only used to more clearly illustrate the technical scheme of the utility model, and cannot be used to limit the protection scope of the utility model.

[0027] Embodiment: this ultra high frequency RFID identification system, this ultra high frequency RFID identification system, including planar antenna array 1, power division phase shift network 2 and ultra high frequency read-write module 3, planar antenna array 1 includes multiple ultra high frequency antenna groups, and multiple ultra high frequency antenna groups are placed in the plane, power division phase shift network 2 is connected respectively with ultra high frequency antenna group and ultra high frequency read-write module 3, multiple ultra high frequency antenna groups are placed in the plane and form planar antenna array, and the ultra high frequency antenna group in it is used for the radiation of specific space of ultra high frequency signal, power division phase shift network 2 is used to change the amplitude and phase of ultra high frequency antenna group signal, realizes the automatic scanning of antenna beam in specific space, the ultra high frequency read-write module 3 is used for the modulation transmission of ultra high frequency signal, demodulation reception and phase control of power division phase shift network, the ultra high frequency antenna group includes multiple linearly arranged antenna elements and independent feed structure, and the feed power ratio is 1:1~8:1, power division phase shift network 2 includes power division network 201 and phase shift network 202, power division network 201 is connected with phase shift network 202 and ultra high frequency antenna group respectively, phase shift network 202 is connected with ultra high frequency antenna group, planar antenna array 1 includes three ultra high frequency antenna groups, and they are first ultra high frequency antenna group 101, second ultra high frequency antenna group 102 and third ultra high frequency antenna group 103, power division phase shift network 2 is connected with first ultra high frequency antenna group 101, second ultra high frequency antenna group 102 and third ultra high frequency antenna group 103 respectively, first ultra high frequency antenna group 101, second ultra high frequency antenna group 102 and third ultra high frequency antenna group 103 are placed in the plane, and form 3x3 nine-element planar antenna array 1, by the different feed power of first ultra high frequency antenna group 101, second ultra high frequency antenna group 102 and third ultra high frequency antenna 13 group, the antenna array side lobe can be reduced, and the space gain outside the main radiation area is rapidly reduced, and the probability of string reading is reduced, and simultaneously, the nine-element planar antenna array 1 formed by first ultra high frequency antenna group 101, second ultra high frequency antenna group 102 and third ultra high frequency antenna 13 group compresses the beam width of two orthogonal directions in the horizontal plane, improves the gain of antenna main radiation direction and the effective aperture of antenna, and further enhances the identification ability of system, wherein the feed power ratio of first ultra high frequency antenna group 101 and third ultra high frequency antenna group 103 is 1:1:1, and the feed power ratio of second ultra high frequency antenna group 102 is 1:8:1.

[0028] The power division network 201 includes a power division input branch 2011 and a plurality of power division output branches, the power division input branch 2011 is connected to the plurality of power division output branches respectively, the power division output branches are connected to the ultra-high frequency antenna group and the phase shift network 202 respectively; the phase shift network 202 includes a phase shift branch and a control port 2023, the control port 2023 is connected to the phase shift branch; the ultra-high frequency reader-writer module 3 is connected to the power division input branch 2011 and the control port 2023; the ultra-high frequency reader-writer module 3 inputs the ultra-high frequency RFID signal through the power division input branch 2011 of the power division phase shift network 2, the input RFID signal is equally divided into three paths through the output branch of the power division network 2; correspondingly, the output branch includes a first power division output branch 2012, a second power division output branch 2013 and a third power division output branch 2014, the power distribution ratio of the first power division output branch 2012, the second power division output branch 2013 and the third power division output branch 2014 is 1:1:1; the phase shift branch includes a first phase shift branch 2021 and a second phase shift branch 2022, the second power division output branch 2013 is connected to the second ultra-high frequency antenna group 102 after phase shift through the first phase shift branch 2021, the signal phase lags / leads the reference phase 22.5° by an integer multiple; the third power division output branch 2014 is connected to the third ultra-high frequency antenna group 103 after phase shift through the second phase shift branch 2022, the signal phase lags / leads the reference phase 45° by an integer multiple; the first power division output branch 2012 is connected to the first ultra-high frequency antenna group 101, and the output signal phase is the reference phase.

[0029] The super high frequency RFID reader module 3 inputs the super high frequency RFID signal through the power division input branch 2011 of the power division phase shift network 2. The input RFID signal is equally divided into three paths through the power division network 201. The first power division output branch 2012 is connected to the first super high frequency antenna group 101. The second power division output branch 2013 is connected to the second super high frequency antenna group 102 after phase shift through the first phase shift branch 2021. The third power division output branch 2014 is connected to the third super high frequency antenna group 103 after phase shift through the second phase shift branch. The first phase shift branch 2021 and the second phase shift branch 2022 are both composed of four high-low PIN diode phase shift units to form a 4-bit digital phase shift network. The phase shift resolution is 22.5°. The high-low PIN diode phase shift network refers to an electrical network containing a high-pass filter branch and a low-pass filter branch of PIN diodes. The high-pass filter branch has a phase lead characteristic, while the low-pass filter branch has a phase lag characteristic. By controlling the on-off of the PIN diode, the signal selects the high-pass branch or the low-pass branch to achieve the desired phase lag or lead. The 4-bit digital refers to a circuit with four high-low filter units controlled by 4-bit digital signals. Therefore, the phase shift resolution of the phase shift network 202 is 3600 / 24, i.e. 22.5°, and the phase shift range is -180°-180°. The negative phase shift angle represents phase lag, and the positive phase shift angle represents phase lead.

[0030] Specifically, as shown in Figure 1 The ceiling super high frequency RFID inventory antenna of the embodiment includes a planar antenna array 1, a power division phase shift network 2, and a super high frequency RFID reader module 3. The planar antenna array 1 includes a first super high frequency antenna group 101, a second super high frequency antenna group 102, and a third super high frequency antenna group 103 for radiating super high frequency signals in a specific space. The power division phase shift network 2 is connected to the first super high frequency antenna group 101, the second super high frequency antenna group 102, and the third super high frequency antenna group 103, respectively, for changing the signal amplitude and phase of the super high frequency antenna groups 12 and 13 to realize automatic scanning of the antenna beam in a specific space. The super high frequency RFID reader module 3 is connected to the input end 2011 and the control end of the power division phase shift network 2 for modulating and transmitting super high frequency signals, demodulating and receiving signals, and controlling the phase of the power division phase shift network.

[0031] As shown in Figure 2 The first super high frequency antenna group 101 includes three linearly arranged first super high frequency antenna group elements 1011, 1012, and 1013, and an independent feeding structure 1014. The second super high frequency antenna group 102, the third super high frequency antenna group 103, and the first super high frequency antenna group 101 have the same topological arrangement form. As shown in Figure 3As shown, the first UHF antenna group 101, the second UHF antenna group 102, and the third UHF antenna group 103 are placed coplanarly to form a 3×3 9-element planar array. The 9 elements of the planar array are fed using a non-uniform feeding method. The feed power ratio of the first UHF antenna group element 1011, the first UHF antenna group element 2012, and the first UHF antenna group element 3013 in the first UHF antenna group 1 is 1:1:1. The feed power ratio of the second UHF antenna group element 1, the second UHF antenna group element 2, and the second UHF antenna group element 3 in the second UHF antenna group 102 is 1:8:1. The feed power ratio of the third UHF antenna group element 1, the third UHF antenna group element 2, and the third UHF antenna group element 3 in the third UHF antenna group 103 is 1:1:1. Therefore, the feed amplitude matrix of the planar array 1 is:

[0032] like Figure 4 As shown, the power divider phase-shifting network 2 includes a power divider network 201 and a phase-shifting network 202. The power divider network 201 consists of an input branch 2011, a first power divider output branch 2012, a second power divider output branch 2013, and a third power divider output branch 2014. The power distribution ratio of the first power divider output branch 2012, the second power divider output branch 2013, and the third power divider output branch 2014 is 1:1:1. The phase-shifting network 202 consists of a first phase-shifting branch 2021, a second phase-shifting branch 2022, and a control port 2013. The UHF reader module 3 receives an UHF RFID signal through the power divider input branch 2011 of the power divider phase-shifting network 2. The input RFID signal is divided into three output paths by the power divider network 201. The first power divider output branch 2012 is connected to the first UHF antenna group 101. The second power divider output branch 2013 is connected to the second UHF antenna group 102 after phase shifting by the first phase-shifting branch 2021. The third power divider output branch 2014 is connected to the third UHF antenna group 103 after phase shifting by the second phase-shifting branch. Specifically, in this embodiment, the phase of the output signal of the first power divider output branch 2012 is the reference phase. The phase of the output signal of the first phase-shifting branch 2021 is lagging or leading the first power divider output branch 2012 by an integer multiple of 22.5°. The phase of the output signal of the second phase-shifting branch 2022 is lagging or leading the first power divider output branch 2012 by an integer multiple of 45°.

[0033] In this embodiment, the first phase-shifting branch 2021 and the second phase-shifting branch 2021 have the same structure and parameters, such as... Figure 5 As shown, the first phase-shifting branch 2021 consists of a first phase-shifting branch high / low pass PIN phase-shifting unit 20221, a first phase-shifting branch high / low pass PIN phase-shifting unit, a first phase-shifting branch high / low pass PIN phase-shifting unit, and a first phase-shifting branch high / low pass PIN phase-shifting unit, forming a 4-bit digital phase-shifting network, as shown. Figure 6As shown. Specifically, the parallel inductor Lp and the series capacitor Cs form a π-type high-pass branch, the PIN diodes PIN1 and PIN2 control the turn-on or turn-off of the high-pass branch, the series inductor Ls and the parallel capacitor Cp form a π-type low-pass branch, and the PIN diodes PIN3 and PIN4 control the turn-on or turn-off of the low-pass branch. The series capacitors C1 and C2 are AC coupling capacitors between different phase-shifting units. R1 and R2 are current-limiting resistors of the control loop, RFC is a radio frequency choke inductor that prevents ultra-high frequency signals from entering the control loop, BIT0 is a control signal, when BIT0 is positive, the high-pass branch is turned on, and the low-pass branch is turned off, when BIT0 is negative, the low-pass branch is turned on, and the high-pass branch is turned off. The four high-low pass PIN phase-shifting units have the same circuit structure, and the circuit element parameters are determined by the following formula:

[0034]

[0035] Where B n is the admittance of the parallel element in the high-pass branch and the low-pass branch, X n is the reactance of the parallel element in the high-pass branch and the low-pass branch, and Δφ is the desired phase shift. Specifically, in this embodiment, the phase shift of the first phase-shifting branch high-low pass PIN phase-shifting unit one 20211 is 22.5°, the phase shift of the first phase-shifting branch high-low pass PIN phase-shifting unit two is 45°, the phase shift of the first phase-shifting branch high-low pass PIN phase-shifting unit three is 90°, and the phase shift of the first phase-shifting branch high-low pass PIN phase-shifting unit four is 180°; wherein the structure of the first phase-shifting branch high-low pass PIN phase-shifting unit two, the first phase-shifting branch high-low pass PIN phase-shifting unit three, and the first phase-shifting branch high-low pass PIN phase-shifting unit four is the same as that of the first phase-shifting branch high-low pass PIN phase-shifting unit one. Therefore, the phase-shifting resolution of the 4-bit digital phase shifter is 22.5°, and the phase-shifting range is -180°-180°. By controlling the phase shift of the second ultra-high frequency antenna group 102 and the third ultra-high frequency antenna group 103, the ultra-high frequency RFID identification system realizes beam scanning in a certain range in a specific direction, as shown in Figure 7 .

[0036] For those skilled in the art, the specific embodiments are only exemplary descriptions of the present application, and obviously the specific implementation of the present application is not limited by the above-mentioned manner, as long as various non-essential improvements are made by adopting the method concept and technical solution of the present application, or the concept and technical solution of the present application is directly applied to other occasions without improvement, which is within the protection scope of the present application.

Claims

1. An ultra-high frequency RFID identification system, characterized by The application relates to a UHF RFID reader module, which comprises a planar antenna array, a power division and phase shift network and a UHF RFID reader module.

2. The ultra-high frequency RFID identification system according to claim 1, characterized in that The UHF antenna group comprises a plurality of linearly arranged antenna elements and an independent feeding structure, and the feeding power ratio is 1:1-8:

1.

3. The UHF RFID identification system of claim 2, wherein The power division and phase shift network comprises a power division network and a phase shift network, and the power division network is connected with the phase shift network and the UHF antenna group respectively.

4. The UHF RFID identification system of claim 3, wherein The planar antenna array comprises three UHF antenna groups, namely a first UHF antenna group, a second UHF antenna group and a third UHF antenna group, and the power division and phase shift network is connected with the first UHF antenna group, the second UHF antenna group and the third UHF antenna group respectively.

5. The UHF RFID identification system of claim 4, wherein The first UHF antenna group, the second UHF antenna group and the third UHF antenna group are coplanarly arranged to form a 9-element planar antenna array with a 3*3 structure.

6. The UHF RFID identification system of claim 4, wherein The power division network comprises a power division input branch and a plurality of power division output branches, the power division input branch is connected with the power division output branches respectively, the power division output branches are connected with the UHF antenna group and the phase shift network respectively, the phase shift network comprises a phase shift branch and a control port, the control port is connected with the phase shift branch, and the UHF RFID reader module is connected with the power division input branch and the control port.

7. The UHF RFID identification system of claim 6, wherein The UHF RFID reader module inputs a UHF RFID signal through the power division input branch of the power division and phase shift network, the input RFID signal is equally divided into three paths through the output branches of the power division network, and correspondingly, the output branches comprise a first power division output branch, a second power division output branch and a third power division output branch.

8. The UHF RFID identification system of claim 7, wherein The phase shift branch comprises a first phase shift branch and a second phase shift branch, the second power division output branch is connected with the second UHF antenna group after phase shift through the first phase shift branch, and the signal phase lags / leads the reference phase by an integer multiple of 22.5 degrees; The third power division output branch is connected with the third UHF antenna group after phase shift through the second phase shift branch, and the signal phase lags / leads the reference phase by an integer multiple of 45 degrees; The first power division output branch is connected with the first UHF antenna group, and the output signal phase is the reference phase.

9. The UHF RFID identification system of claim 5, wherein, The feeding power ratios of the first UHF antenna group and the third UHF antenna group are both 1:1:1, and the feeding power ratio of the second UHF antenna group is 1:8:

1.

10. The UHF RFID identification system of claim 8, wherein, The first phase shift branch and the second phase shift branch both comprise four high-low PIN diode phase shift units to form a 4-bit digital phase shift network, and the phase shift resolution is 22.5 degrees.

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