A beam switching system and access control device

Abstract

The application relates to a beam switching system and a door access device, which comprises a plurality of antenna arrays, a plurality of electric bridges and two power dividers, the number of the antenna arrays is the same as that of the electric bridges; each antenna array is connected with an electric bridge; the two input ends of the electric bridge are connected with one output port of the two power dividers; and the input port of the power divider is connected with the radio frequency port of an RFID reader and writer. The beam switching system and the door access device provided by the application can detect the moving track of a label through beam switching, can realize more reasonable beam coverage through the setting of two RFID reader and writer ports, can reduce the misreading range, and can improve the store space utilization and user experience.

Description

Technical Field

[0001] This invention relates to the field of beam switching technology in RFID, and particularly to a beam switching system and access control device. Background Technology

[0002] Existing RFID technology is a wireless technology that uses radio frequency energy to propagate through space to achieve contactless information transmission and identify targets through the transmitted information. Access control systems are an important application area of ​​RFID technology. They can be used for personnel identification, as well as for identifying, authenticating, and alarming items passing through the access control area. This system is widely used in various settings such as libraries, archives, retail, and asset management. RFID access control systems provide an important technical means to improve the security level of public places and enhance service levels.

[0003] Current access control systems typically consist of a multi-port reader and multiple fixed-gain antennas, specifically circularly polarized antennas with gains ranging from 4dB to 12dB in the UHF band. The number of antennas also varies from 2 to 8. The limitations of this approach include the inability to determine the direction of tag movement and a large range of false readings. In some supermarkets, clothing stores, libraries, and archives, where goods are densely packed and the flow of people and goods is frequent and irregular, this limitation of conventional access control systems leads to frequent false alarms and reduced product display space, severely impacting store operational efficiency and the customer shopping experience. Summary of the Invention

[0004] This invention provides a beam switching system and access control device, which solves the problems of existing access control systems being unable to detect the movement trajectory of tags and having a large range of misreading.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A beam switching system and access control device include: a plurality of antenna elements, a plurality of bridges and two power dividers, wherein the number of antenna elements is the same as the number of bridges;

[0007] Each of the antenna elements is connected to a bridge circuit;

[0008] Both input terminals of the bridge are connected to one of the output ports of the two power dividers;

[0009] The input port of the power divider is connected to the radio frequency port of the RFID reader.

[0010] Preferably, the antenna array and the bridge are connected by two first radio frequency transmission lines, which have the same characteristic impedance and electrical length. Specifically, they can be microstrip lines, coplanar waveguides, or coaxial lines.

[0011] Preferably, the bridge, the first radio frequency transmission line, and the antenna array together form a circularly polarized antenna unit.

[0012] Preferably, the bridge and the power divider are connected via a second radio frequency transmission line. The second radio frequency transmission line has the same characteristic impedance but different electrical lengths, enabling phase shifting at different angles.

[0013] Preferably, the second radio frequency transmission line connecting a power divider to each bridge is a set of cables, and the electrical lengths of the two sets of cables increase and decrease in an arithmetic sequence, respectively, with a step size of 30°-150°.

[0014] Preferably, each of the power dividers forms a signal transmission path with all the bridges and antenna elements, and forms a beam radiation effect.

[0015] Preferably, the bridge is a 3dB bridge with a four-port network device, the two input ports are isolated from each other, and the two output ports are 90° out of phase but have the same amplitude.

[0016] An access control device includes any of the beam switching systems and access control devices described above.

[0017] By implementing the above technical solutions, the following technical effects are achieved: The beam switching system and access control device provided by this invention can detect the movement trajectory of tags through beam switching. By setting two RFID reader ports, more reasonable beam coverage can be achieved, the range of misreading can be reduced, and the utilization rate of store space and user experience can be improved. Attached Figure Description

[0018] Figure 1 A schematic diagram illustrating the working principle of Embodiment 1 of the present invention;

[0019] Figure 2 A schematic diagram illustrating the working principle of Embodiment 2 of the present invention;

[0020] Figure 3 The application effect diagram of Embodiment 3 provided by the present invention;

[0021] Figure 4 A top view showing the application effect of Embodiment 3 of the present invention. Detailed Implementation

[0022] To better understand the technical solution of the present invention, the embodiments provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Example 1

[0024] like Figure 1As shown, this embodiment provides a beam switching system comprising: a plurality of antenna elements, a plurality of bridges, and two power dividers. The number of antenna elements is the same as the number of bridges. Each antenna element is connected to one bridge. Both input terminals of each bridge are connected to one output port of the two power dividers. The input ports of the power dividers are connected to the radio frequency ports of an RFID reader / writer. The antenna elements and bridges are connected via two first radio frequency transmission lines having the same characteristic impedance and electrical length. Specifically, these first radio frequency transmission lines can be microstrip lines, coplanar waveguides, or coaxial lines.

[0025] The bridge circuit and the power divider are connected via a second radio frequency (RF) transmission line. This second RF transmission line has the same characteristic impedance but different electrical lengths, enabling phase shifting at different angles. The electrical length of the second RF transmission line can be set according to actual usage requirements, varying depending on the beam direction requirements.

[0026] In this embodiment, the system includes three antenna arrays A1, A2, and A3; three 3dB bridges H1, H2, and H3; two power dividers D1 and D2; six first radio frequency transmission lines L11, L12, L21, L22, L31, and L32; six second radio frequency transmission lines C1, C2, C3, C4, C5, and C6; and two RFID reader radio frequency input ports RFin1 and RFin2.

[0027] The antenna elements A1, A2, and A3 are spatially arranged in a linear array, which forms different beams under different amplitude and phase combinations. The bridge, the first radio frequency transmission line, and the antenna elements together form a circularly polarized antenna unit. That is, in this embodiment, antenna element A1, the first radio frequency transmission lines L11 and L12, and the 3dB bridge H1 form a circularly polarized antenna unit; similarly, antenna element A2, the first radio frequency transmission lines L21 and L22, and the 3dB bridge H2 form a circularly polarized antenna unit; and antenna element A3, the first radio frequency transmission lines L31 and L32, and the 3dB bridge H3 form a circularly polarized antenna unit.

[0028] Each power divider forms a signal transmission path with all the bridges and antenna elements, creating a beam radiation effect. In this embodiment, the 3dB bridges H1, H2, H3, the second RF transmission lines C1, C2, C3, and the power divider D1 form one state of the phase-shift control network; the 3dB bridges H1, H2, H3, the second RF transmission lines C4, C5, C6, and the power divider D2 form another state of the phase-shift control network. The second RF transmission lines C1, C2, and C3 have different electrical lengths, achieving different angles of phase shift for the RF signal. Similarly, C4, C5, and C6 have different electrical lengths, achieving different directions of phase shift for the RF signal. The second RF transmission lines connecting a power divider to each bridge form a set of cables, with the electrical lengths of the two sets of cables increasing and decreasing in an arithmetic progression, respectively, with a step size of 30°-150°. As an example, the phase shift angles of C1, C2, and C3 are 90°, 120°, and 150°, respectively; the phase shift angles of C4, C5, and C6 are 150°, 120°, and 90°, respectively. In this embodiment, the power dividers D1 and D2 are 1-to-3 power dividers, which can have equal or unequal amplitudes. In other embodiments, 1-to-2, 1-to-4, and 1-to-5 power dividers can also be used, in which case the corresponding number of bridges and antenna elements will be changed accordingly. The bridge in this embodiment is a 3dB bridge with a four-port network device. The two input ports are isolated from each other, and the two output ports are 90° out of phase but have the same amplitude.

[0029] When the RFID reader or module selects RFin1 as the working port, the radio frequency signal is fed into the bridge H1, H2, and H3 via the power divider D1 and the second radio frequency transmission lines C1, C2, and C3, and then radiated out from the antenna array A1, A2, and A3. When the phase shift angles of C1, C2, and C3 meet certain requirements, this antenna array obtains the radiation pattern shown in the front right of the figure.

[0030] Similarly, when the RFID reader or module selects RFin2 as the working port, the radio frequency signal is fed into the bridge H1, H2, and H3 via the power divider D2 and the second radio frequency transmission lines C4, C5, and C6, and then radiated out from the antenna array A1, A2, and A3. When C4, C5, and C6 meet another phase shift requirement, this antenna array obtains the radiation pattern shown in the front left of the figure.

[0031] Example 2

[0032] like Figure 2As shown, in this embodiment, there are two antenna elements and two bridges. The number of first radio frequency transmission lines and second radio frequency transmission lines is also reduced accordingly. In this embodiment, antenna element A1, first radio frequency transmission lines L11, L12 and 3dB bridge H1 form a circularly polarized antenna unit. Similarly, antenna element A2, first radio frequency transmission lines L21, L22 and 3dB bridge H2 form a circularly polarized antenna unit. And so on. In other embodiments, it can also be configured to have 4, 5 or more circularly polarized antenna units.

[0033] Example 3

[0034] like Figure 3 and 4 As shown, this embodiment provides an access control device, including any of the beam switching systems and access control devices described above. One beam switching system is placed on each side of the access control channel, forming four beams covering the path of personnel or goods. RFID readers or devices continuously poll these ports, obtaining tag data and corresponding location information. With the location information, the service layer selects one or more beam ranges for alarm, thus reducing the overall alarm range.

[0035] The beam switching system and access control device provided by the embodiments of the present invention have been described in detail above. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A beam switching system, characterized in that, include: The system comprises several antenna elements, several bridge circuits, and two power dividers, wherein the number of antenna elements is the same as the number of bridge circuits. Each of the antenna elements is connected to a bridge circuit; Both input terminals of the bridge are connected to one of the output ports of the two power dividers; The input port of the power divider is connected to the radio frequency port of the RFID reader / writer. The radio frequency port of the RFID reader / writer can operate independently or switch between different modes to achieve beam switching. The antenna array is connected to the bridge via two first radio frequency transmission lines, which have the same characteristic impedance and electrical length. The bridge, the first radio frequency transmission line, and the antenna array together form a circularly polarized antenna unit. The bridge circuit and the power divider are connected via a second radio frequency transmission line. The second radio frequency transmission line has the same characteristic impedance but different electrical lengths, which can achieve phase shift at different angles. The second RF transmission line connecting a power divider to each bridge is a set of cables. The electrical lengths of the two sets of cables increase and decrease in an arithmetic sequence, respectively, with a step size of 30°-150°.

2. The beam switching system according to claim 1, characterized in that, The first radio frequency transmission line is specifically in the form of a microstrip line, a coplanar waveguide, or a coaxial line.

3. The beam switching system according to claim 1, characterized in that, Each of the power dividers forms a signal transmission path with all the bridges and antenna elements, and creates a beam radiation effect.

4. The beam switching system according to claim 1, characterized in that, The bridge is a 3dB bridge with a four-port network device. The two input ports are isolated from each other, and the two output ports are 90° out of phase but have the same amplitude.

5. An access control device, characterized in that, Includes a beam switching system and access control device as described in any one of claims 1-4.

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