CN117895215A - RFID reader-writer antenna - Google Patents

Abstract

The application discloses an RFID reader-writer antenna, and relates to the technical field of communication equipment. The RFID reader-writer antenna comprises a substrate, a feed network, a grounding body and at least two radiators arranged at intervals, wherein the substrate is provided with a first surface and a second surface which are arranged in a back-to-back mode, the grounding body is arranged on the first surface, the feed network and the radiators are arranged on the second surface, the feed network is provided with feed ports corresponding to the radiators one by one, the radiators are respectively and electrically connected with the feed ports, and the signal phase difference of the adjacent radiators is 90 degrees. The scheme can solve the problem that the conventional RFID reader-writer antenna cannot achieve both small size and wide frequency band.

Description

RFID reader-writer antenna

Technical Field

The application belongs to the technical field of communication equipment, and particularly relates to an RFID reader-writer antenna.

Background

RFID (Radio Frequency Identification ) is one of automatic identification technologies, and is used for non-contact bidirectional data communication in a wireless radio frequency mode, and reading and writing of a recording medium (an electronic tag or a radio frequency card) in a wireless radio frequency mode, so that the purposes of identification and data exchange are achieved. According to different working frequencies, the RFID can be classified into Low Frequency (LF), high Frequency (HF), ultra High Frequency (UHF), microwave and other different types, wherein UHF RFID refers to a type of RFID technology using 860-960MHz frequency band.

Because UHF RFID has the characteristics of long recognition distance, high recognition rate, high transmission rate and the like, _. UHF RFID is widely applied to an RFID system at present, and is a technology for realizing data acquisition between an RFID reader antenna and an RFID electronic tag antenna through a backscattering modulation principle, wherein the capability of the RFID reader antenna for transmitting and receiving radio frequency signals is particularly important for energy interaction of the RFID system, however, the contradiction which is difficult to avoid exists in the design process of the RFID reader antenna, namely, the continuously reduced antenna size is difficult to consider the broadband characteristic due to the reduction of radiation performance.

Disclosure of Invention

The embodiment of the application aims to provide an RFID reader-writer antenna, which can solve the problem that the conventional RFID reader-writer antenna cannot achieve both small size and wide frequency band.

In order to solve the technical problems, the application is realized as follows:

The embodiment of the application provides an RFID reader-writer antenna, which comprises a substrate, a feed network, a grounding body and at least two radiators arranged at intervals, wherein the substrate is provided with a first surface and a second surface which are arranged oppositely, the first surface is provided with the grounding body, the second surface is provided with the feed network and each radiator, the feed network is provided with feed ports corresponding to the radiators one by one, each radiator is respectively and electrically connected with each feed port, and the signal phase difference of the adjacent radiators is 90 degrees.

In the embodiment of the application, the RFID reader-writer antenna comprises at least two radiators, the feed ports of the feed network are arranged in one-to-one correspondence with the radiators and are electrically connected, and the signal phase difference of the adjacent radiators is 90 degrees, so that a spiral antenna is formed, and the size of the RFID reader-writer antenna can be reduced on the basis of ensuring that the spiral antenna has a wider frequency band due to good circular polarization characteristic and radiation performance, so that the occupied space of the spiral antenna is reduced. Therefore, the application can solve the problem that the current RFID reader-writer antenna cannot achieve both small size and wide frequency band.

Drawings

Fig. 1 to fig. 3 are schematic structural diagrams of an RFID reader antenna according to an embodiment of the present application under different viewing angles;

FIG. 4 is a bottom view of an RFID reader antenna according to an embodiment of the present application;

FIG. 5 is a graph showing a change in voltage standing wave ratio of an input port of an RFID reader antenna according to an embodiment of the present application;

FIG. 6 is a radiation pattern of an RFID reader antenna in an XOZ plane according to an embodiment of the present application;

Fig. 7 is a radiation pattern of an RFID reader antenna in the YOZ plane according to an embodiment of the present application.

Reference numerals illustrate:

100-a substrate;

200-feeding network, 201-feeding port, 202-first signal line, 203-first power divider, 204-first sub-signal line, 205-second sub-signal line, 206-main signal line, 207-second signal line, 208-second power divider, 209-third power divider, 210-third sub-signal line, 211-fourth sub-signal line, 212-input port;

300 ground body, 310-ground inlet;

400-radiator, 410-radiator, 420-supporting part, 421-notch, 422-first connecting column, 423-second connecting column, 430-first radiator, 440-second radiator, 450-third radiator, 460-fourth radiator;

500-coaxial cable;

600-bonding pads;

700-ground block.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that some, but not all embodiments of the application are described. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present application may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.

The RFID reader antenna provided by the embodiment of the application is described in detail below through specific embodiments and application scenes thereof with reference to the accompanying drawings.

As shown in fig. 1 to 4, the embodiment of the application discloses an RFID reader antenna, optionally, the RFID reader antenna may be applied to a warehouse, a base station room, an intelligent transportation system, an intelligent medical system, a book management system, and the like, which is not particularly limited.

The RFID reader antenna includes a substrate 100, a feed network 200, a grounding body 300, and at least two spaced radiators 400, and optionally, the substrate 100 may be made of an FR-4PCB board, or may be made of a high frequency board or other structures, which is not particularly limited in the embodiment of the present application. The substrate 100 has a first surface and a second surface disposed opposite to each other, the first surface is provided with a grounding body 300, and the potential of the grounding body 300 is zero, that is, the grounding body 300 has a zero potential structure, alternatively, the grounding body 300 may have a metal structure, or may have other structures, which is not limited herein. The second face is provided with a feed network 200 and each radiator 400, the feed network 200 has feed ports 201 in one-to-one correspondence with the radiators 400, and each radiator 400 is electrically connected to each feed port 201, respectively, so that the feed network 200 supplies power to each radiator 400, thereby causing each radiator 400 to radiate electromagnetic waves. The phase difference of signals of adjacent radiators 400 is 90 °.

In the embodiment of the application, the RFID reader antenna comprises at least two radiators 400, the feed ports 201 of the feed network 200 are arranged in one-to-one correspondence with the radiators 400 and are electrically connected, the signal phase difference of the adjacent radiators 400 is 90 degrees, so that a spiral antenna is formed, and the size of the RFID reader antenna can be reduced on the basis of ensuring that the spiral antenna has a relatively good circular polarization characteristic and radiation performance, so that the occupied space of the spiral antenna is reduced. Therefore, the application can solve the problem that the current RFID reader-writer antenna cannot achieve both small size and wide frequency band.

In an alternative embodiment, the output power of each feeding port 201 is equal, and the current flowing into each radiator 400 is substantially equal, so that the electromagnetic wave energy radiated by each radiator 400 is substantially consistent, which is beneficial to improving the uniformity of circularly polarized radiation of the RFID reader antenna. Of course, the output power of each of the power supply ports 201 may be unequal.

Alternatively, each radiator 400 may be individually controlled, powered by a different signal line; or in an alternative embodiment, the feeding network 200 includes a first signal line 202, a first power divider 203, a first sub-signal line 204 and a second sub-signal line 205, where an output end of the first signal line 202 is electrically connected to an input end of the first power divider 203, an output end of the first power divider 203 is electrically connected to an input end of the first sub-signal line 204 and an input end of the second sub-signal line 205, respectively, and the output end of the first sub-signal line 204 and the output end of the second sub-signal line 205 are each provided with a feeding port 201, and optionally, a length of the second sub-signal line 205 is greater than a length of the first sub-signal line 204, so that the feeding port 201 of the second sub-signal line 205 is 90 ° out of phase with a signal of the feeding port 201 of the first sub-signal line 204. In this scheme, the current in the first signal line 202 is divided into two paths after passing through the first power divider 203, one path flows to the first sub-signal line 204, and the other path flows to the second sub-signal line 205, that is, the first power divider 203 adopts a form of dividing the current in the first signal line 202 into two parts, so that the radiators 400 corresponding to the first sub-signal line 204 and the second sub-signal line 205 respectively radiate electromagnetic waves, thereby simplifying the signal line arrangement of the feed network 200; in addition, the first power divider 203 adopts a one-to-two distribution mode, which has small energy loss and is beneficial to improving the radiation performance of the radiator 400. Of course, the first power divider 203 may also adopt a one-to-three or one-to-four dividing mode.

In a further alternative embodiment, the feeding network 200 further includes a main signal line 206, a second signal line 207, a second power divider 208, a third power divider 209, a third sub signal line 210 and a fourth sub signal line 211, where an output end of the second signal line 207 is electrically connected to an input end of the second power divider 208, an output end of the second power divider 208 is electrically connected to an input end of the third sub signal line 210 and an input end of the fourth sub signal line 211, respectively, and a feeding port 201 is provided at an output end of the third sub signal line 210 and an output end of the fourth sub signal line 211, and optionally, a length of the fourth sub signal line 211 is greater than a length of the third sub signal line 210, so that a signal phase difference between the feeding port 201 of the fourth sub signal line 211 and the feeding port 201 of the third sub signal line 210 is 90 °. The output end of the main signal line 206 is electrically connected to the input end of the third power divider 209, and the output ends of the third power divider 209 are electrically connected to the input end of the first signal line 202 and the input end of the second signal line 207, and optionally, the length of the first signal line 202 is longer than the length of the second signal line 207, so that the signal phase difference between the output end of the first signal line 202 and the output end of the second signal line 207 is 90 °. In this scheme, when the number of radiators 400 is greater than two, the feed network 200 adopts a pyramid mode to distribute current, and the first power divider 203, the second power divider 208 and the third power divider 209 all adopt a one-to-two distribution mode, so that not only can the structure of the feed network 200 be simplified, but also the loss of the whole feed network 200 can be reduced, thereby improving the radiation performance of the whole RFID reader antenna.

It should be noted that at least one of the first power divider 203, the second power divider 208, and the third power divider 209 may be replaced with a coupler.

In an alternative embodiment, an isolation resistor is disposed between the first output branch line and the second output branch line of at least one of the first power divider 203, the second power divider 208, and the third power divider 209, that is, at least one of the first power divider 203, the second power divider 208, and the third power divider 209 is a wilkinson power divider, which has good bandwidth and low loss characteristics, so that the radiator 400 disposed at the terminal has a higher impedance matching characteristic; in addition, the setting of the isolation resistor can avoid the mutual influence between the signals transmitted to the feed ports 201, so as to improve the isolation between the feed ports 201, further improve the matching performance of the radiators 400, and improve the stability of the signals fed into the radiators 400. Of course, the first power divider 203, the second power divider 208, and the third power divider 209 may also be T-shaped power dividers.

In another alternative embodiment, the feed network 200 further has an input port 212, the ground body 300 has a ground inlet 310, the rfid reader antenna further includes a coaxial cable 500, and the conductive center line of the coaxial cable 500 is electrically connected to the radiator 400 through the input port 212, so as to supply power to the feed network 200; the conductive layer of the coaxial cable 500 is electrically connected to the ground body 300 through the ground inlet 310 such that the ground body 300 has a zero potential configuration. Because the coaxial cable 500 has the characteristics of small loss, good anti-interference performance and high broadband support, the coaxial cable 500 is electrically connected with the feed network 200 and the grounding body 300 respectively, so that the loss can be reduced, the energy introduced into the feed network 200 can be improved, and the radiation performance of the radiator 400 can be improved. Of course, other types of cables may be used for feeding.

Alternatively, the coaxial cable 500 may be directly electrically connected to the grounding body 300 or the feeding network 200 through a via on the substrate 100; or in other embodiments, the RFID reader antenna further includes a pad 600, where the pad 600 is disposed on the substrate 100, alternatively, the pad 600 may be a via pad, which has a low inductance and is suitable for a high-density PCB board, so as to promote space saving.

Optionally, the coaxial cable 500 is disposed on the first surface, and the conductive layer of the coaxial cable 500 is electrically connected to the grounding inlet 310 of the grounding body 300 through the bonding pad 600, so that on the basis of facilitating the electrical connection between the coaxial cable 500 and the radiator 400, the connection stability and the electrical connection performance between the coaxial cable 500 and the grounding body 300 can be increased; in addition, the coaxial cable 500 is disposed on the first surface of the substrate 100, which is beneficial to improving the flatness of the grounding body 300, and facilitating the assembly of the whole RFID reader antenna to the installation base.

In another embodiment, the coaxial cable 500 is disposed on the second surface, and the conductive center line of the coaxial cable 500 is electrically connected to the input port 212 of the feed network 200 through the bonding pad 600, so that the connection stability and the electrical connection performance between the coaxial cable 500 and the radiator 400 can be ensured on the basis of facilitating the electrical connection between the coaxial cable 500 and the grounding body 300; in addition, the coaxial cable 500 is disposed on the second surface of the substrate 100, so that the number of components on the second surface can be reduced, and the difficulty in arranging the feed network 200 can be reduced.

Alternatively, each radiator 400 may be provided at a central region of the substrate 100; in another alternative embodiment, the radiators 400 are all disposed at the edge of the substrate 100 and are arranged at intervals along the circumferential direction of the substrate 100, so that the radiators 400 are disposed in a dispersed manner, so that mutual interference between the radiators 400 can be avoided, and the electromagnetic wave energy distribution range of the RFID reader antenna can be enlarged.

Optionally, each radiator 400 includes a radiator 410 and a supporting portion 420 that are connected, where the radiator 410 is bent relative to the supporting portion 420, alternatively, an included angle between the radiator 410 and the supporting portion 420 may be 90 °, and at this time, each radiator 400 has an inverted L-shaped structure, so as to reduce the height of the whole RFID reader antenna, make the whole antenna structure more compact, and reduce the size of the RFID reader antenna; and the backward radiation performance of the inverted L-shaped radiator is weaker, so that the spiral antenna is formed. The supporting portion 420 is electrically connected to the feed network 200 and the grounding body 300, and in the circumferential direction of the substrate 100, the first ends of the radiating vibrators 410 of the radiating bodies 400 and the second ends of the radiating vibrators 410 of the radiating bodies 400 are sequentially and alternately arranged, that is, the rotation directions of the radiating bodies 400 are the same, so that the circular polarization characteristic of the whole RFID reader antenna is improved, and the anti-interference performance of the whole RFID reader antenna is further improved. Of course, the radiator 400 in this embodiment may also have other types of structures such as T-shape, which is not limited in particular by the embodiment of the present application.

Optionally, the circular polarization form of the RFID reader antenna disclosed by the application may be left-handed circular polarization, where each radiator 400 is in a right-handed arrangement state; of course, the circular polarization of the RFID reader antenna disclosed in the present application may be right-hand circular polarization, where each radiator 400 is in a left-hand arrangement state.

Alternatively, radiating element 410 may be made of aluminum alloy tin plating, copper, or other metallic materials, which embodiments of the present application are not particularly limited.

In a further alternative embodiment, the supporting portion 420 is provided with a notch 421 to form a first connection post 422 and a second connection post 423, that is, the first connection post 422 and the second connection post 423 are disposed at intervals, the first end of the first connection post 422 and the first end of the second connection post 423 are connected to the first end of the radiating oscillator 410, the second end of the first connection post 422 is electrically connected to the feeding network 200, and the second end of the second connection post 423 is electrically connected to the grounding body 300. According to the scheme, the notch 421 is formed, so that the impedance matching characteristic of the radiator 400 and the feed network 200 can be adjusted, and the radiation performance of the radiator 400 is improved. Of course, the RFID reader antenna disclosed in the present application can also adjust the impedance matching performance between the feeding network 200 and the radiator 400 by changing the structure of the feeding network 200.

Alternatively, the shape of the notch 421 may be rectangular, so as to facilitate processing, but may also be triangular, U-shaped, etc., which is not particularly limited in the embodiment of the present application.

Alternatively, the second end of the second connection post 423 may be electrically connected to the ground body 300 through the substrate 100; or in other embodiments, the RFID reader antenna further includes a grounding block 700, where the grounding block 700 is disposed on the first surface, and the grounding block 700 is disposed at a distance from the feeding network 200, where the grounding block 700 is provided with a through hole, and the substrate 100 is provided with a connection hole, where the connection hole is electrically connected with the through hole (specifically, a metal layer may be laid on the side walls of the connection hole and the through hole to make the metal layer electrically conductive, so as to implement electrical connection), so that the grounding block 700 is electrically conductive with the grounding body 300, that is, the grounding block 700 corresponds to one port of the grounding body 300. The second end of the second connection post 423 is electrically connected to the grounding block 700, and at this time, the second connection post 423 of the radiator 400 is electrically connected to the grounding block 300 through the grounding block 700, so as to facilitate the setting of the radiator 400. Optionally, the second connection post 423 and the grounding block 700 may be connected by welding or the like, so as to improve the connection firmness between the two, and meanwhile, improve the stability of the radiator 400.

In alternative embodiments, the number of radiators 400 may be two or three; or the at least two radiators 400 include a first radiator 430, a second radiator 440, a third radiator 450 and a fourth radiator 460, and the first radiator 430, the second radiator 440, the third radiator 450 and the fourth radiator 460 are all disposed at the edge of the substrate 100 and are arranged at intervals along the circumference of the substrate 100, and at this time, the signal phases in the first radiator 430, the second radiator 440, the third radiator 450 and the fourth radiator 460 are respectively 0 °, 90 °, 180 ° and 270 ° in sequence, so that the electromagnetic wave radiated by the antenna of the whole RFID reader-writer is distributed more uniformly within 360 °, thereby improving the out-of-roundness of the whole antenna.

Optionally, in an embodiment in which the output power of each feeding port 201 is equal, the at least two radiators 400 include a first radiator 430, a second radiator 440, a third radiator 450 and a fourth radiator 460, where the power ratio of each feeding port 201 to each radiator 400 is 1:1:1:1, so that the energy from the feed source is equally distributed to each radiator 400 through the feeding network 200, so as to further improve the circular polarization characteristic of the RFID reader antenna.

Alternatively, the feeding network 200 may be a microstrip line, which has the characteristics of small size, light weight, wide frequency band, high reliability, and easy connection with a solid device; or the feeding network 200 may be a coplanar waveguide, which also has the characteristics of small volume and light weight, and the planar structure of the coplanar waveguide makes it convenient to obtain the characteristics of linear polarization, circular polarization, dual polarization, and the like.

Alternatively, the thickness of the substrate 100 may be 1mm, which may be flexibly selected according to practical needs, and the embodiment of the present application is not limited thereto. Alternatively, the substrate 100 may have a rectangular structure, so as to be convenient for manufacturing, or may have a circular structure, a hexagonal structure, or even a special-shaped structure, which is not particularly limited in the embodiment of the present application; further alternatively, when the substrate 100 is a rectangular structure, corners of the rectangular structure may be rounded to avoid scratching other structures during installation.

Alternatively, the base plate 100 may be provided with mechanical holes to facilitate fixing to the mounting base by rivets, screws or the like.

Optionally, the electrical connection manner between the structures described above may be a solder connection manner, and since the solder has good wettability, a uniform liquid soldering interface may be formed on the soldering surface, so as to promote the contact and diffusion between the soldering material and the soldering surface; in addition, the soldering tin has good conductivity and can provide good electric connection performance; in addition, the solderability of the solder is good, so the reliability of the solder connection mode is high.

Optionally, based on the RFID reader-writer antenna disclosed by the application, as can be seen from fig. 5, in the 860-960MHz frequency band, the voltage standing wave ratio is smaller than 1.2, which indicates that the impedance matching of the input port of the antenna is better; further, referring to fig. 6 and 7, it is shown that the circular polarization characteristic of the RFID reader antenna is good.

The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are to be protected by the present application.

Claims (11)

1. The RFID reader-writer antenna is characterized by comprising a substrate (100), a feed network (200), a grounding body (300) and at least two radiators (400) which are arranged at intervals, wherein the substrate (100) is provided with a first surface and a second surface which are arranged in a back-to-back mode, the grounding body (300) is arranged on the first surface, the feed network (200) and each radiator (400) are arranged on the second surface, the feed network (200) is provided with feed ports (201) which are in one-to-one correspondence with the radiators (400), each radiator (400) is electrically connected with each feed port (201) respectively, and the signal phase difference of adjacent radiators (400) is 90 degrees.

2. The RFID reader antenna according to claim 1, characterized in that the output power of each of the feed ports (201) is equal.

3. The RFID reader antenna according to claim 1, characterized in that the feed network (200) comprises a first signal line (202), a first power divider (203), a first sub-signal line (204) and a second sub-signal line (205), an output end of the first signal line (202) is electrically connected to an input end of the first power divider (203), an output end of the first power divider (203) is electrically connected to an input end of the first sub-signal line (204) and an input end of the second sub-signal line (205), respectively, and an output end of the first sub-signal line (204) and an output end of the second sub-signal line (205) are both provided with the feed port (201).

4. An RFID reader antenna according to claim 3, characterized in that the feed network (200) further comprises a main signal line (206), a second signal line (207), a second power divider (208), a third power divider (209), a third sub signal line (210) and a fourth sub signal line (211), the output of the second signal line (207) is electrically connected to the input of the second power divider (208), the output of the second power divider (208) is electrically connected to the input of the third sub signal line (210) and the input of the fourth sub signal line (211), respectively, the output of the third sub signal line (210) and the output of the fourth sub signal line (211) are provided with the feed port (201), the output of the main signal line (206) is electrically connected to the input of the third power divider (209), and the output of the third power divider (209) is electrically connected to the input of the first signal line (202) and the input of the second sub signal line (207).

5. The RFID reader antenna according to claim 4, characterized in that an isolation resistor is provided between the first output leg and the second output leg of at least one of the first power divider (203), the second power divider (208) and the third power divider (209).

6. The RFID reader antenna of claim 1, wherein the feed network (200) further has an input port (212), the ground body (300) has a ground inlet (310), the RFID reader antenna further comprises a coaxial cable (500), a conductive center line of the coaxial cable (500) is electrically connected to the radiator (400) through the input port (212), and a conductive layer of the coaxial cable (500) is electrically connected to the ground body (300) through the ground inlet (310).

7. The RFID reader antenna of claim 6, further comprising a pad (600), the pad (600) being disposed on the substrate (100),

The coaxial cable (500) is arranged on the first surface, and the conductive layer of the coaxial cable (500) is electrically connected with the grounding inlet (310) through the bonding pad (600); or alternatively, the first and second heat exchangers may be,

The coaxial cable (500) is disposed on the second face, and the conductive center line of the coaxial cable (500) is electrically connected to the input port (212) through the pad (600).

8. The RFID reader antenna according to claim 1, wherein each radiator (400) is disposed at an edge of the substrate (100) and is arranged at intervals along a circumferential direction of the substrate (100), each radiator (400) includes a radiator (410) and a supporting portion (420) that are connected, the radiator (410) is bent with respect to the supporting portion (420), the supporting portion (420) is electrically connected to the feed network (200) and the grounding body (300), respectively, and in the circumferential direction of the substrate (100), a first end of the radiator (410) of each radiator (400) and a second end of the radiator (410) of each radiator (400) are sequentially alternately arranged.

9. The RFID reader antenna according to claim 8, wherein the supporting portion (420) is provided with a notch (421) to form a first connection post (422) and a second connection post (423), the first end of the first connection post (422) and the first end of the second connection post (423) are both connected to the first end of the radiating element (410), the second end of the first connection post (422) is electrically connected to the feed network (200), and the second end of the second connection post (423) is electrically connected to the grounding body (300).

10. The RFID reader antenna according to claim 9, further comprising a grounding block (700), the grounding block (700) being disposed on the first face, the grounding block (700) being disposed at an interval from the feeding network (200), the grounding block (700) being provided with a through hole, the substrate (100) being provided with a connection hole, the connection hole being electrically connected with the through hole, so that the grounding block (700) is electrically connected with the grounding body (300), the second end of the second connection post (423) being electrically connected with the grounding block (700).

11. The RFID reader antenna according to claim 1, wherein the at least two radiators (400) include a first radiator (430), a second radiator (440), a third radiator (450), and a fourth radiator (460), and the first radiator (430), the second radiator (440), the third radiator (450), and the fourth radiator (460) are all disposed at an edge of the substrate (100) and are arranged at intervals along a circumferential direction of the substrate (100).