RFID reader antenna

Abstract

This application discloses an RFID reader antenna, relating to the field of wireless communication technology. The RFID reader antenna includes a substrate, a radiator, a feed line, and a ground plane. The substrate has a first side and a second side arranged opposite to each other. The radiator and the feed line are both disposed on the first side. The radiator includes a first radiating segment and a second radiating segment arranged vertically. A first end of the first radiating segment is connected to a first end of the second radiating segment. The ground plane is disposed on the second side and has a slot. The slot is opposite to the radiator and includes a first slot segment and a second slot segment arranged vertically. The first slot segment and the second slot segment are connected. A first end of the feed line is connected to the radiator, and a second end of the feed line is a power supply port. This solution can solve the problem of the current difficulty in RFID reader antenna layout.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology, specifically relating to an RFID reader antenna. Background Technology

[0002] RFID (Radio Frequency Identification) is a type of automatic identification technology that uses wireless radio frequency for non-contact, two-way data communication. It reads and writes data to recording media (electronic tags or RFID cards) to achieve identification and data exchange. Based on their operating frequency, RFID can be categorized into low-frequency (LF), high-frequency (HF), ultra-high-frequency (UHF), and microwave types. UHF RFID refers to a type of RFID technology that utilizes the 860-960MHz frequency band.

[0003] RFID antennas mainly include RFID tag antennas and RFID reader antennas. UHF RFID reader antennas need to have wide bandwidth and circular polarization characteristics. They are usually microstrip antennas, consisting of a radiating patch and a ground plane. Their radiation direction is only upwards from the radiating patch, while there is almost no radiation energy on the side of the ground plane. In applications such as UHF RFID smart cabinets, microstrip antennas are usually set up in two ways: one is to place them at the bottom of the cabinet, which will result in greater polarization loss of the microstrip antenna, thus reducing its reading effect; the other is to place them on the side wall, in which case the reading distance on one side of the microstrip antenna is longer, resulting in poor reading effect. Therefore, the layout of a single microstrip antenna is quite difficult, and usually two microstrip antennas are needed to achieve the purpose of reading tags on both sides, but this will increase production costs. Summary of the Invention

[0004] The purpose of this application is to provide an RFID reader antenna that can solve the problem of the current difficulty in RFID reader antenna layout.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] This application provides an RFID reader antenna, including a substrate, a radiator, a feed line, and a ground plane. The substrate has a first side and a second side arranged opposite to each other. The radiator and the feed line are both disposed on the first side. The radiator includes a first radiating segment and a second radiating segment arranged vertically. A first end of the first radiating segment is connected to a first end of the second radiating segment. The ground plane is disposed on the second side and has a gap. The gap is arranged opposite to the radiator and includes a first gap segment and a second gap segment arranged vertically. The first gap segment and the second gap segment are connected. A first end of the feed line is connected to the radiator, and a second end of the feed line is a power supply port.

[0007] In this embodiment, both the radiator and the feed line are disposed on the first surface of the substrate. The radiator includes a first radiating segment and a second radiating segment arranged vertically. The first end of the first radiating segment is connected to the first end of the second radiating segment. A ground plane is disposed on the second surface of the substrate, and a slot is formed in the ground plane. The slot is positioned opposite to the radiator. The radiator is electromagnetically coupled to the slot of the ground plane to form a slot antenna. The slot includes a first slot segment and a second slot segment arranged vertically, and the first slot segment is connected to the second slot segment. The first end of the feed line is connected to the radiator, and the second end of the feed line is a feed port. When current is applied to the feed port, the radio frequency signal in the circuit enters the antenna from the feed port. At this time, based on the bidirectional radiation principle of the slot antenna, the radiator radiates circularly polarized waves with different rotation directions in its normal direction, thereby achieving bidirectional circularly polarized radiation performance. In other words, this application can achieve the purpose of reading tags on both sides by setting only one RFID reader antenna, which is beneficial to improving its deployment flexibility. In addition, compared with the prior art, which uses two microstrip antennas, it can reduce costs. Attached Figure Description

[0008] Figures 1 to 2 These are schematic diagrams of the antenna disclosed in the embodiments of this application from different viewing angles;

[0009] Figure 3 The reflection coefficient curves of the feed port of the antenna disclosed in this application at different resonant frequencies are shown.

[0010] Figure 4 This is a graph showing the variation of the axial ratio parameter of the antenna disclosed in the embodiments of this application at different angles;

[0011] Figure 5 This is the 2DE plane radiation pattern of the circularly polarized antenna disclosed in the embodiments of this application;

[0012] Figure 6 This is the antenna radiation pattern of the left-hand circularly polarized 2DE plane disclosed in the embodiments of this application;

[0013] Figure 7 This is the radiation pattern of the right-hand circularly polarized 2DE plane of the antenna disclosed in the embodiments of this application.

[0014] Explanation of reference numerals in the attached figures:

[0015] 100 - Substrate, 110 - First surface, 120 - Second surface;

[0016] 200 - Radiator, 210 - First radiating segment, 220 - Second radiating segment;

[0017] 300 - Feeder line, 310 - First feeder line segment, 320 - Second feeder line segment, 330 - Third feeder line segment, 340 - First feeder line, 350 - Second feeder line;

[0018] 400 - Grounding plate, 410 - Gap, 411 - First gap segment, 411a - First groove, 412 - Second gap segment, 412a - Second groove, 420 - Frame, 430 - Center body. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The RFID reader antenna provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0022] refer to Figures 1 to 2This application discloses an RFID reader antenna, including a substrate 100, a radiator 200, a feed line 300, and a ground plane 400. Optionally, the ground plane 400 can be a metal structure, or other structures, which are not specifically limited here. The substrate 100 has a first surface 110 and a second surface 120 arranged opposite to each other. The radiator 200 and the feed line 300 are both disposed on the first surface 110. The radiator 200 includes a first radiating segment 210 and a second radiating segment 220 arranged vertically. Both the first radiating segment 210 and the second radiating segment 220 can be linear structures. The first end of the first radiating segment 210 is connected to the first end of the second radiating segment 220. The ground plane 400 is disposed on the second surface 120 and has a slot 410. The slot 410 and the radiator 200 are arranged opposite to each other along the thickness direction of the substrate 100. The radiator 200 is electromagnetically coupled to the slot 410 of the ground plane 400 to form a slot antenna. The slot 410 includes a vertical... The first slit segment 411 and the second slit segment 412 are set in a straight line. Both the first slit segment 411 and the second slit segment 412 can be straight structures. The first slit segment 411 and the second slit segment 412 are connected. The first end of the feed line 300 is connected to the radiator 200, and the second end of the feed line 300 is a power supply port. When the power supply port is powered, the first radiating segment 210 and the second radiating segment 220 of the radiator 200 generate two mutually perpendicular current components, thereby forming a circularly polarized wave above the radiator 200. The first slit segment 411 and the second slit segment 412 generate two mutually perpendicular current components, thereby forming a circularly polarized wave below the radiator 200, thus achieving the purpose of a double circularly polarized wave.

[0023] In this embodiment, after current is supplied to the antenna's feed port, the radio frequency signal in the circuit enters the antenna from the feed port. Based on the bidirectional radiation principle of the slot antenna, the radiator 200 radiates circularly polarized waves with different rotation directions in its normal direction, thereby achieving bidirectional circularly polarized radiation performance. In other words, this application only requires one RFID reader antenna to achieve the purpose of reading tags on both sides, which is beneficial to improving its deployment flexibility. Furthermore, compared to the prior art's method of using two microstrip antennas, it can reduce costs. Therefore, this embodiment can solve the problem of the current difficulty in RFID reader antenna layout. In addition, the radiator in this application adopts a non-contact coupling feed method, which has the characteristics of conveniently adjusting the input impedance and expanding the antenna bandwidth.

[0024] It should be noted that the current supplied to the feed port of the antenna disclosed in this application is alternating current, and the positive and negative values ​​of the alternating current are used to change the direction of rotation of the surface current inside the radiator 200.

[0025] In one optional embodiment, the inner wall of the first slot segment 411 is provided with a first groove 411a, and the inner wall of the second slot segment 412 is provided with a second groove 412a, thereby optimizing the axial ratio of the antenna and improving its circular polarization characteristics. Of course, if the length and width of the first slot segment 411 and the second slot segment 412 are set appropriately, the first groove 411a and the second groove 412a may not be provided.

[0026] Optionally, during antenna fabrication, the axial ratio of the antenna can be further adjusted by adjusting the length of the first groove 411a along the extension direction of the first slot segment 411 and the length of the second groove 412a along the extension direction of the second slot segment 412, thereby improving the circular polarization characteristics of the antenna and reducing its polarization loss. Alternatively, in other embodiments, the depths of the first groove 411a and the second groove 412a can be adjusted to further optimize the axial ratio of the antenna, thereby improving its circular polarization characteristics and reducing its polarization loss.

[0027] Optionally, the first groove 411a and the second groove 412a can both be located at a position far from the connection between the first slot segment 411 and the second slot segment 412. However, the coupling effect of the radiator 200 is weaker at this position, and correspondingly, less electromagnetic wave energy is radiated. Based on this, in another optional embodiment, the first groove 411a and the second groove 412a are both located near the connection between the first end of the first slot segment 411 and the first end of the second slot segment 412. Here, the coupling effect of the radiator 200 is stronger, and correspondingly, more electromagnetic wave energy is radiated by the slot antenna, thereby improving the antenna's readout effect.

[0028] In another optional embodiment, the opening of the first groove 411a is opposite to the second slot segment 412 along the extension direction of the second slot segment 412, and the opening of the second groove 412a is opposite to the first slot segment 411 along the extension direction of the first slot segment 411. In this case, both the first groove 411a and the second groove 412a are located in the central region of the substrate 100 and are relatively dispersed. This not only facilitates the arrangement of the first groove 411a and the second groove 412a, but also brings them closer to the connection between the first end of the first slot segment 411 and the first end of the second slot segment 412, which is beneficial to improving the radiation performance of the slot antenna and thus improving the antenna readout effect. Of course, the first groove 411a and the second slot segment 412 can also be arranged side by side along the extension direction of the first slot segment 411, and the second groove 412a and the first slot segment 411 can also be arranged side by side along the extension direction of the second slot segment 412. However, in this case, the radiation performance of the slot antenna is not as good as the previous arrangement.

[0029] It should be noted that the depth of the first groove 411a and the depth of the second groove 412a may be equal or unequal, and can be flexibly adjusted according to actual needs. This application embodiment does not impose specific limitations in this regard. In addition, the groove width of the first groove 411a and the groove width of the second groove 412a may be equal or unequal, and can be flexibly adjusted according to actual needs. This application embodiment does not impose specific limitations in this regard.

[0030] Optionally, the depth of the first groove 411a and the depth of the second groove 412a can both be 0.5 to 2 mm. Of course, they can also be flexibly adjusted according to actual needs. This application embodiment does not impose specific limitations on this.

[0031] In an optional embodiment, the width of the first groove 411a is equal to the width of the second slit segment 412, and the direction of this width is parallel to the extension direction of the first slit segment 411. Similarly, the width of the second groove 412a is equal to the width of the first slit segment 411, and the direction of this width is parallel to the extension direction of the first slit segment 411. This ensures that the sidewall of the second end of the first groove 411a away from the first slit segment 411 is perpendicularly connected to the sidewall of the second end of the second groove 412a away from the second slit segment 412. In this case, the first groove 411a and the second groove 412a are spaced apart to prevent the two slits generated by the first slit segment 411 and the second slit segment 412 from being separated. The mutually perpendicular current components avoid mutual interference, thereby improving the circular polarization characteristics of the radiator 200 and achieving polarization isolation of the circularly polarized waves formed above and below the radiator 200. In addition, the width of the first groove 411a is equal to the width of the second slot segment 412, and the width of the second groove 412a is equal to the width of the first slot segment 411. During the antenna manufacturing process, when the second slot segment 412 is opened, the processing tool can be extended to the side wall of the first slot segment 411 to form the first groove 411a, and when the first slot segment 411 is opened, the processing tool can be extended to the side wall of the second slot segment 412 to form the second groove 412a, thereby facilitating the antenna manufacturing process.

[0032] In another optional embodiment, the ratio between the depth of the first groove 411a and the width of the first slot segment 411 is 0.1 to 0.3, so that the antenna has a better circularly polarized wave and facilitates the setting of the first groove 411a. Of course, the above ratio can also be less than 0.1, in which case the depth of the first groove 411a is smaller, which is not convenient for setting.

[0033] Optionally, the ratio between the depth of the first groove 411a and the width of the first slit segment 411 can be 0.15 to 0.2 to further optimize the axial ratio of the antenna and improve the circular polarization characteristics of the antenna; further optionally, the ratio can be 0.17, and of course it can be adjusted according to actual needs, without specific limitations here.

[0034] In other embodiments, the ratio between the depth of the second groove 412a and the width of the second slot segment 412 is 0.1 to 0.3, so that the antenna has a better circularly polarized wave and facilitates the setting of the second groove 412a. Of course, the above ratio can also be less than 0.1, in which case the depth of the second groove 412a is smaller, which is not convenient for setting.

[0035] Optionally, the ratio between the depth of the second groove 412a and the width of the second slit segment 412 can be 0.15 to 0.2 to further optimize the axial ratio of the antenna and improve the circular polarization characteristics of the antenna; further optionally, the ratio can be 0.17, and of course it can be adjusted according to actual needs, without specific limitations here.

[0036] Optionally, in the direction perpendicular to the substrate 100, the outline of the orthographic projection of the radiator 200 can coincide with the outline of the orthographic projection of the slot 410, that is, the width and length of the radiator 200 are equal to the width and length of the slot 410. In this case, the coupling effect of the radiator 200 is weak, and less electromagnetic energy is coupled to the slot 410. Therefore, in other embodiments, in the direction perpendicular to the substrate 100, the orthographic projection of the radiator 200 is located within the orthographic projection of the slot 410, that is, the width of the radiator 200 is smaller than the width of the slot 410, and the length of the radiator 200 is less than or equal to the length of the slot 410, thereby enhancing the coupling effect of the radiator 200, increasing the electromagnetic energy coupled to the slot 410, and thus improving the readout effect of the antenna.

[0037] In another optional embodiment, the feed line 300 includes a first feed line segment 310, a second feed line segment 320, and a third feed line segment 330 connected sequentially. The first feed line segment 310 and the third feed line segment 330 are arranged opposite to each other, and the first feed line segment 310 is connected to the radiator 200. This structure of the feed line 300 in this scheme helps improve the impedance matching of the antenna, thereby enhancing the antenna's radiation performance. Optionally, the lengths of the first feed line segment 310 and the third feed line segment 330 can be equal.

[0038] Optionally, during antenna fabrication, the impedance matching of the antenna can be adjusted by regulating the length of the second feed line segment 320, i.e., adjusting the distance between the first feed line segment 310 and the third feed line segment 330, thereby controlling the imaginary part of the impedance at the feed port of the feed line 300 and thus improving the antenna's radiation performance. Alternatively, in other embodiments, the impedance matching of the antenna can be adjusted by regulating the width of the feed line 300, thereby controlling the real part of the impedance at the feed port of the feed line 300 and thus improving the antenna's radiation performance.

[0039] Optionally, the ground plane 400 can be a single-piece structure; alternatively, the ground plane 400 includes a spaced-apart frame 420 and a central body 430, i.e., the frame 420 and the central body 430 are separate, with the central body 430 located within the frame 420. The feed line 300 and the frame 420 are positioned opposite each other to form a microstrip transmission line. The radiator 200 and the central body 430 are positioned opposite each other, and the central body 430 has a slot 410. When the radiator 200 radiates electromagnetic waves, these waves will be concentrated at the central body 430 and scattered outwards. At this time, the beamwidth of the electromagnetic waves is relatively narrow. The spaced-apart frame 420 is used to increase the beamwidth of the electromagnetic waves, thereby improving the antenna's coverage and propagation distance, and thus enhancing the antenna's readout performance.

[0040] Optionally, the shape of the border 420 can be circular, polygonal, etc.; or, in other embodiments, the border 420 is a rectangular structure. In this case, the shape of the border 420 is relatively regular, so as to facilitate the structural setting of the feed line 300, thereby improving the transmission performance of the microstrip transmission line formed by the feed line 300 and the border 420.

[0041] Optionally, the first radiating segment 210 is perpendicular to the second radiating segment 220, and the first radiating segment 210 and the second radiating segment 220 are symmetrically arranged about the first axis, that is, the length of the first radiating segment 210 is equal to the length of the second radiating segment 220, and the width of the first radiating segment 210 is equal to the width of the second radiating segment 220, which is beneficial to further improve the circular polarization characteristics of the antenna. Optionally, the first axis coincides with the diagonal of the frame 420. In this case, the frame 420 has a square structure, and the length of the frame 420 is equal to the width of the frame 420, which facilitates the arrangement of the frame 420 and the central body 430. Of course, the first axis can also coincide with the vertical or horizontal axis of symmetry of the frame 420, but the circular polarization characteristics of the antenna in this arrangement are not as good as the arrangement where the first axis coincides with the diagonal of the frame 420.

[0042] Optionally, the first slot segment 411 is perpendicular to the second slot segment 412, and the first slot segment 411 and the second slot segment 412 are symmetrically arranged about the second axis. The projections of the second axis and the first axis in the direction perpendicular to the substrate 100 coincide, thereby improving the electromagnetic coupling strength of the radiator 200 and enhancing the radiation performance of the slot antenna.

[0043] Optionally, the central body 430 can be a regular polygonal structure such as an equilateral triangle or a square. In this case, with the frame 420 fixed, the length of the slot 410 on the central body 430 is relatively short, resulting in less energy coupled from the radiator 200 to the slot 410, thus leading to lower utilization of the radiator 200. Therefore, in another optional embodiment, the central body 430 is a circular structure, with its center point coinciding with the center point of the frame 420. In this case, the length of the slot 410 can be set to be longer, thereby increasing the energy coupled from the radiator 200 to the slot 410 and improving the utilization of the radiator 200. Optionally, the connection between the first slot segment 411 and the second slot segment 412 can be located in the central region of the central body 430, thereby improving the circular polarization characteristics of the antenna.

[0044] Optionally, the number of feed lines 300 can be one. In this case, the first end of the feed line 300 can be connected to the second end of the first radiating section 210 or the second end of the second radiating section 220, and the antenna feeding method is relatively simple. Therefore, in another optional embodiment, the number of feed lines 300 is at least two, including a first feed line 340 and a second feed line 350. The first end of the first feed line 340 is connected to the second end of the first radiating section 210, and the first end of the second feed line 350 is connected to the second end of the second radiating section 220. The number of feed ports is at least two, including a first feed port and a second feed port. The second end of the first feed line 340 is the first feed port, and the second end of the second feed line 350 is the second feed port. That is to say, the second end of the first feed line 340 or the second end of the second feed line 350 can be selected for feeding, and the user can flexibly choose according to actual needs. When the second end of the first feed line 340 and the second end of the second feed line 350 are fed respectively, the circular polarization directions of the upper and lower parts of the radiator 200 will be reversed. For example, when the second end of the first feed line 340 is fed, the upper part of the radiator 200 is left-hand circularly polarized and the lower part is right-hand circularly polarized; correspondingly, when the second end of the second feed line 350 is fed, the upper part of the antenna is right-hand circularly polarized and the lower part is left-hand circularly polarized.

[0045] Furthermore, when the feeder 300 includes a first feeder segment 310, a second feeder segment 320, and a third feeder segment 330 connected in sequence, one of the first feeder 340 and the second feeder 350 may include the first feeder segment 310, the second feeder segment 320, and the third feeder segment 330 connected in sequence, or both may include the first feeder segment 310, the second feeder segment 320, and the third feeder segment 330 connected in sequence.

[0046] Optionally, the substrate 100 can be made of FR-4 PCB material, with dimensions of 90mm in length, 90mm in width, and 1.6mm in height (thickness). This results in a smaller overall antenna size and lower cost. Furthermore, actual testing shows that the antenna gain disclosed in this embodiment can reach approximately 3dB, with a 3dB beamwidth of approximately 100deg, which meets the requirements of conventional UHF RFID smart cabinets or racks.

[0047] In addition, refer to Figures 3 to 7 , Figure 3 The graph shows the reflection coefficient curves of the antenna's feed port at different resonant frequencies. The horizontal axis represents the resonant frequency, and the vertical axis represents the ratio of the energy input to the antenna's feed port to the reflected energy. The larger the absolute value of this ratio, the less energy is reflected back and the more energy enters the antenna. In the frequency band with a bandwidth of 0.84 GHz to 1 GHz, the absolute value is greater than 10 dB, indicating that the antenna's feed port has good impedance matching performance.

[0048] Figure 4 This is a graph showing the variation of the axial ratio parameter of the antenna disclosed in this application at different angles, where the horizontal axis represents the angle and the vertical axis represents the axial ratio of the antenna. Figure 4 The curves showing the axial ratio change when phi = 0° and phi = 90° are given. Figure 4 It can be seen that the axial ratio of the antenna disclosed in this application is less than 3dB, that is, the circular polarization characteristics of the antenna are good.

[0049] Figure 5 The image shows the 2DE plane radiation pattern of the circularly polarized antenna disclosed in this application. The solid line represents phi = 0° and the dashed line represents phi = 90°. It can be seen that the circularly polarized waves above and below the antenna are axially symmetrically distributed.

[0050] Figure 6 The image shows the radiation pattern of the left-hand circularly polarized 2DE plane of the antenna disclosed in this application. The solid line represents phi = 0° and the dashed line represents phi = 90°. It can be seen that the left-hand circularly polarized performance of the antenna is good.

[0051] Figure 7 The image shows the radiation pattern of the right-hand circularly polarized 2DE plane of the antenna disclosed in this application. The solid line represents phi = 0° and the dashed line represents phi = 90°. It can be seen that the right-hand circularly polarized performance of the antenna is good.

[0052] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. An RFID reader antenna, characterized in that, The system includes a substrate (100), a radiator (200), a feed line (300), and a ground plane (400). The substrate (100) has a first surface (110) and a second surface (120) arranged opposite to each other. The radiator (200) and the feed line (300) are both disposed on the first surface (110). The radiator (200) includes a first radiating segment (210) and a second radiating segment (220) arranged vertically. The first end of the first radiating segment (210) is connected to the first end of the second radiating segment (220). The ground plane (400) is disposed on the second surface (120). The ground plane (400) has a slot (410) which is opposite to the radiator (200). The slot (410) includes a first slot segment (411) and a second slot segment (412) arranged vertically. The first slit segment (411) is connected to the second slit segment (412). The inner wall of the first slit segment (411) is provided with a first groove (411a), and the inner wall of the second slit segment (412) is provided with a second groove (412a). The first groove (411a) and the second groove (412a) are both located near the connection between the first end of the first slit segment (411) and the first end of the second slit segment (412). The opening of the first groove (411a) is opposite to the second slit segment (412) along the extension direction of the second slit segment (412), and the opening of the second groove (412a) is opposite to the first slit segment (411) along the extension direction of the first slit segment (411). The first end of the feed line (300) is connected to the radiator (200), and the second end of the feed line (300) is a power supply port.

2. The RFID reader antenna according to claim 1, characterized in that, The width of the first groove (411a) is equal to the width of the second slit segment (412), and the width of the second groove (412a) is equal to the width of the first slit segment (411), so that the sidewall of the second end of the first groove (411a) away from the first slit segment (411) is perpendicularly connected to the sidewall of the second end of the second groove (412a) away from the second slit segment (412).

3. The RFID reader antenna according to claim 1, characterized in that, The ratio between the depth of the first groove (411a) and the width of the first slit segment (411) is 0.1 to 0.3; The ratio between the depth of the second groove (412a) and the width of the second slit segment (412) is 0.1 to 0.

3.

4. The RFID reader antenna according to claim 1, characterized in that, In a direction perpendicular to the substrate (100), the orthographic projection of the radiator (200) lies within the orthographic projection of the slit (410).

5. The RFID reader antenna according to claim 1, characterized in that, The feed line (300) includes a first feed line segment (310), a second feed line segment (320) and a third feed line segment (330) connected in sequence. The first feed line segment (310) and the third feed line segment (330) are arranged opposite to each other. The first feed line segment (310) is connected to the radiator (200).

6. The RFID reader antenna according to claim 1, characterized in that, The ground plane (400) includes a frame (420) and a center body (430) spaced apart. The center body (430) is disposed within the frame (420). The feed line (300) is disposed opposite to the frame (420). The radiator (200) is disposed opposite to the center body (430). The center body (430) has the gap (410).

7. The RFID reader antenna according to claim 6, characterized in that, The frame (420) is a rectangular structure, and the first radiating segment (210) and the second radiating segment (220) are symmetrically arranged about a first axis, which coincides with the diagonal of the frame (420); and / or, The central body (430) has a circular structure, and the center point of the central body (430) coincides with the center point of the border (420).

8. The RFID reader antenna according to claim 1, characterized in that, The number of feed lines (300) is at least two, including a first feed line (340) and a second feed line (350). The first end of the first feed line (340) is connected to the second end of the first radiating section (210), and the first end of the second feed line (350) is connected to the second end of the second radiating section (220). The number of power supply ports is at least two, including a first power supply port and a second power supply port. The second end of the first feed line (340) is the first power supply port, and the second end of the second feed line (350) is the second power supply port.

Images