TWI559615B - Multi-band antenna - Google Patents

Description

Multi-band antenna

The present invention relates to an antenna, and more particularly to a multi-band antenna.

The traditional five-frequency antenna usually adopts the Planar inverted-F antenna (PIFA) type as the main design prototype, as shown in Fig. 1 is an example of a planar inverted-F antenna type. Referring to FIG. 1 , the planar inverted-F antenna 100 has a short-circuit pin 110 connected to the ground plane 150 and a feed-in point 130 for receiving the feed signal 135 .

With the rapid evolution of communication technology, the rapid development of the fourth-generation mobile communication system Long Term Evolution (LTE) technology in recent years can support more frequency bands, which can support the frequency system from 698 megahertz (MHz). Up to 2690MHz, including nearly eight bands (700/850/900/1800/1900/2100/2300/2600). However, the conventional five-frequency antenna is limited by the design of the mechanism (for example, the antenna configuration space is limited), and it is difficult to satisfy the long-term frequency band of the long-term evolution technology by a conventional method of extending the length of the resonance path. For example, Figure 2 shows the return loss of a conventional five-band antenna. Figure. Referring to FIG. 2, it can be seen from the return loss curve of FIG. 2 that the conventional five-band antenna cannot effectively support the 700/2300/2600 MHz band of the LTE technology. Accordingly, there is a need to propose an antenna design that meets more frequency bands in the design constraints of the mechanism.

The invention provides a multi-band antenna, which increases the low-frequency bandwidth through capacitive coupling, and adds parasitic components to increase the high-frequency frequency band, thereby increasing the bandwidth and amplifying the support frequency band.

A multi-band antenna of the present invention includes a radiating element, a first parasitic element, and a second parasitic element. The radiating element has a first radiating section, a second radiating section, a third radiating section and a fourth radiating section. The first parasitic element has a first ground point. The first parasitic element and the second radiating section have a first coupling pitch, and operate through the first radiating section and the second radiating section to operate in the first frequency band. The first parasitic element and the fourth radiating section have a second coupling pitch and operate in the second frequency band through the first radiating section, the third radiating section and the fourth radiating section. The second parasitic element has two second ground points, and the second parasitic element and the two second ground points form a "ㄇ" shaped appearance. The second parasitic element has a third coupling pitch between the third radiating section and operates through the first radiating section and the third radiating section to operate in the third frequency band.

In an embodiment of the invention, the first end of the first radiating section has a feeding point, and the second end of the first radiating section is electrically connected to the first end of the second radiating section. The second end of the second radiating section is an open end and the sides of the second radiating section are opposite to the first parasitic element. The first radiating section and the second radiating section constitute an L word Shape appearance.

In an embodiment of the invention, the first end of the third radiating section is electrically connected to the side of the first radiating section, and the first end of the third radiating section is from the side of the first radiating section. The second end of the third radiating section is electrically connected to the first end of the fourth radiating section. The side of the third radiating section is opposite to the second parasitic element, and the other side of the third radiating section is opposite to the second radiating section. The second end of the fourth radiating section is an open end and is opposite to the first parasitic element, and the third radiating section and the fourth radiating section form an L-shaped appearance.

In an embodiment of the invention, the first end of the first parasitic element has a first ground end, and the second end of the first parasitic element is an open end and opposite to the second end of the fourth radiating section. The first end of the second parasitic element has one of the second ground ends adjacent to the feed point, and the second end of the second parasitic element has another second ground.

In an embodiment of the present invention, the multi-band antenna forms a first current path through the first radiating section, the second radiating section, and the first parasitic element, and transmits the first radiating section, the third radiating section, and the first The fourth radiating section and the first parasitic element form a second current path, and form a third current path through the first radiating section, the third radiating section, and the second parasitic element. The length of the third current path is less than the length of the first current path, and the length of the first current path is less than the length of the second current path.

In an embodiment of the invention, the first frequency band is between the 1700 MHz frequency band and the 2100 MHz frequency band, the second frequency band is between the 700 MHz frequency band and the 900 MHz frequency band, and the third frequency band is between the 2300 MHz frequency band and the 2600 MHz frequency band.

In an embodiment of the invention, the feed point, the first ground point, and the two second ground points are all on the same side and are arranged in a straight line.

In an embodiment of the invention, the first coupling pitch, the second coupling pitch, and the third coupling pitch are between 0.8 millimeters (mm) and 1.2 millimeters.

In an embodiment of the invention, the first parasitic element, the second parasitic element, and the radiating element are all located in the same plane.

In an embodiment of the invention, the first parasitic element, the second parasitic element, and a portion of the radiating element of the portion are located on different planes.

In an embodiment of the invention, the first parasitic element, the second parasitic element, or the radiating element are etched from a metal layer on a metal layer of the printed circuit board.

Based on the above, the present invention operates in the first frequency band and the second frequency band by coupling the radiating element with the first parasitic element, and is coupled to the second frequency band by the radiating element and the second parasitic element. Therefore, the embodiment of the present invention can support the 700MHz frequency band to the 900MHz frequency band, the 1700MHz frequency band to the 2100MHz frequency band, and the 2300MHz frequency band to the 2600MHz frequency band to conform to all frequency bands supported by the current LTE technology. In addition, the embodiment of the present invention can further configure a part of the radiating element, the first parasitic element and the second parasitic element on different planes of the three-dimensional substrate according to the design requirement of the mechanism, thereby improving the elasticity of the antenna design.

The above described features and advantages of the invention will be apparent from the following description.

100‧‧‧ Planar inverted F antenna

110‧‧‧Short-circuited feet

130, FP‧‧‧ feed points

135‧‧‧Feeding signal

150‧‧‧ ground plane

30, 60‧‧‧Multi-band antenna

300, 600‧‧‧radiation components

310, 610‧‧‧First Radiation Section

311‧‧‧First end of the first radiation section

315‧‧‧second end of the first radiation section

317‧‧‧Side side of the first radiant section

320, 620‧‧‧second radiation section

321‧‧‧ the first end of the second radiating section

325‧‧‧ second end of the second radiating section

327, 329‧‧‧ side of the second radiating section

330, 630‧‧‧ Third Radiation Section

331‧‧‧ the first end of the third radiating section

335‧‧‧second end of the third radiating section

337, 339‧‧‧ side of the third radiating section

340, 640‧‧‧fourth radiation section

341‧‧‧ the first end of the fourth radiation section

345‧‧‧second end of the fourth radiating section

360, 660‧‧‧ first parasitic element

361‧‧‧ the first end of the first parasitic element

365‧‧‧The second end of the first parasitic element

380, 680‧‧‧ second parasitic element

381‧‧‧ the first end of the second parasitic element

385‧‧‧ second end of the second parasitic element

390, 690‧‧‧Matching components

391‧‧‧The first end of the matching component

395‧‧‧The second end of the matching component

410‧‧‧First current path

430‧‧‧second current path

450‧‧‧ third current path

510‧‧‧second frequency band

530‧‧‧First frequency band

550‧‧‧ third frequency band

601‧‧‧ first plane

602‧‧‧ second plane

603‧‧‧ third plane

604‧‧‧fourth plane

CG1, CG4‧‧‧ first coupling spacing

CG2, CG5‧‧‧second coupling spacing

CG3, CG6‧‧‧ third coupling spacing

DR1, DR2‧‧‧ reference direction

GP1‧‧‧first grounding point

GP2‧‧‧second grounding point

Figure 1 shows an example of a planar inverted-F antenna type.

2 is a diagram of a return loss of a conventional five-band antenna.

FIG. 3 is a schematic structural diagram of a multi-band antenna according to an embodiment of the present invention.

4 is a schematic illustration of a first current path, a second current path, and a third current path.

FIG. 5 is a diagram showing return loss of a multi-band antenna according to an embodiment of the present invention.

6A and 6B are schematic diagrams showing the structure of a multi-band antenna according to another embodiment of the present invention.

In order to improve the bandwidth supported by the antenna and to compensate for the shortage of the low frequency band and the high frequency band, the embodiment of the present invention transmits the first coupling pitch and the second coupling pitch between the radiating element having the feeding point and the first parasitic element. The coupling operation is performed in the first frequency band (for example, the 1700 MHz band to the 2100 MHz band) and the second frequency band (for example, the 700 MHz band to the 900 MHz band), and the third coupling pitch between the radiating element and the second parasitic element is coupled, and the coupling operation is performed. The three bands (for example, the 2300MHz band to the 2600MHz band) are used to achieve the eight frequency bands used by Long Term Evolution (LTE) technology. In addition, a part of the radiating element, the first parasitic element and the second parasitic element may be disposed on the same plane or different planes (for example, disposed on the three-dimensional substrate) to improve the elasticity of the design path. Several implementations consistent with the spirit of the present invention are presented below For example, those applying the present embodiment can appropriately adjust these embodiments according to their needs, and are not limited to the contents in the following description.

FIG. 3 is a schematic structural diagram of a multi-band antenna according to an embodiment of the present invention. Referring to FIG. 3, the multi-band antenna 30 includes a radiating element 300, a first parasitic element 360, and a second parasitic element 380. The radiating element 300 has a first radiating section 310, a second radiating section 320, a third radiating section 330 and a fourth radiating section 340. The first radiating section 310 has a feed point FP. The first radiating section 310 is electrically connected to the second radiating section 320, the first radiating section 310 is electrically connected to the third radiating section 330, and the third radiating section 330 and the fourth radiating section 340 are electrically connected. link. The first parasitic element 360 has a ground point GP1. The first parasitic element 360 and the second radiating section 320 have a first coupling pitch CG1. The first parasitic element 360 and the fourth radiating section 340 have a second coupling pitch CG2. The second parasitic element 380 has two second ground points GP2. The second parasitic element 380 and the two second ground points GP2 form a "ㄇ" shaped appearance. The second parasitic element 380 has a third coupling pitch CG3 between the third radiating section 330.

In this embodiment, the multi-band antenna 30 operates through the first radiating section 310 and the second radiating section 320 to operate in the first frequency band, and transmits the first radiating section 310, the third radiating section 330, and the fourth radiating area. The segment 340 operates in the second frequency band and operates in the third frequency band through the first radiation segment 310 and the third radiation segment 330. The first frequency band is between the 1700MHz frequency band and the 2100MHz frequency band (ie, 1700MHz~2170MHz), the second frequency band is between the 700MHz frequency band and the 900MHz frequency band (ie, 698MHz~960MHz), and the third frequency band is between the 2300MHz frequency band. to Between the 2600MHz bands (ie, 2300MHz~2690MHz). In some embodiments, the first frequency band can be the frequency doubled frequency band of the second frequency band. For example, the first frequency band is between the 1800 MHz band and the 1900 MHz band, and the second band is between the 700 MHz band and the 900 MHz band.

In terms of the current path, the multi-band antenna 30 forms a first current path through the first radiating section 310, the second radiating section 320, and the first parasitic element 360, and transmits the first radiating section 310 and the third radiating section 330. The fourth radiating section 340 and the first parasitic element 360 form a second current path, and form a third current path through the first radiating section 310, the third radiating section 330, and the second parasitic element 380. Wherein the length of the third current path is less than the length of the first current path, and the length of the first current path is less than the length of the second current path. In other words, based on the length of the current path (or the resonant path), the third frequency band is greater than the first frequency band and the first frequency band is greater than the second frequency band.

4 is used as an example for illustration. FIG. 4 is a schematic example of a first current path, a second current path, and a third current path. Referring to FIG. 4, in operation, the multi-band antenna 30 receives the feed signal through the feed point FP of the first radiating section 310. In the first current path 410, the feed signal will flow through the first radiating section 310 and the second radiating section 320, and the first parasitic element 360 is excited through the first coupling pitch CG1 to make the multi-band antenna 30 permeable. The first parasitic element 360 produces a first resonant mode that is operable in the first frequency band. In the second current path 430, the feed signal will flow through the first radiating section 310, the third radiating section 330 and the fourth radiating section 340, and excite the first parasitic element 360 through the second coupling pitch CG2, so that Make more The band antenna 30 can generate a second resonant mode through the first parasitic element 360, thereby operating in the second frequency band. In addition, in the third current path 450, the feed signal will flow through the first radiating section 310 and the third radiating section 330, and the second parasitic element 380 is excited through the third coupling pitch CG3 to cause the multi-band antenna 30. A third resonant mode can be generated by the second parasitic element 380, which in turn can operate in the third frequency band.

In other words, the radiating element 300 can create a capacitive coupling effect with the first parasitic element 360 and the second parasitic element 380, respectively. As such, the multi-band antenna 30 can generate the first resonant mode and the second resonant mode through the first parasitic element 360, and can also generate the third resonant mode through the second parasitic element 380. Therefore, the multi-frequency antenna 100 can operate in three frequency bands, and thus can conform to all frequency bands supported by the LTE technology.

For example, FIG. 5 is a diagram of return loss of multi-band antenna 30 in accordance with an embodiment of the present invention. Referring to FIG. 5, the multi-band antenna 30 is operable in the second frequency band 510, the first frequency band 530, and the third frequency band 550. The first frequency band 530 can cover the 1800 MHz band to the 2100 MHz band, the second band 510 can cover the 700 MHz band to the 900 MHz band, and the third band 550 can cover the 2300 MHz band to the 2600 MHz band.

Please continue to refer to Figure 3. In the detailed architecture of the multi-band antenna 30, the first end 311 of the first radiating section 310 has a feed point FP, and the first end 315 of the first radiating section 310 and the first end of the second radiating section 320 The terminal 321 is electrically connected. The second end 325 of the second radiating section 320 is an open end and the side 327 of the second radiating section 320 is opposite the first parasitic element 360. The first radiating section 310 and the second radiating section 320 constitute an L-shaped appearance.

The first end 331 of the third radiating section 330 is electrically coupled to the side 317 of the first radiating section 310, and the first end 331 of the third radiating section 330 is perpendicular to the side 317 of the first radiating section 310. The second end 335 of the third radiating section 330 is electrically coupled to the first end 341 of the fourth radiating section 340. In other words, the first end 331 of the third radiating section 330 extends to the direction of its second end 335, the same direction as the first end 321 of the second radiating section 320 extends to its second end 325. For example, reference direction DR1. Furthermore, the side 337 of the third radiating section 330 is opposite to the second parasitic element 380, and the other side 339 of the third radiating section 330 is opposite to the second radiating section 320 (the side of the second radiating section 320) 329). That is, the third radiating section 330 is interposed between the second radiating section 320 and the second parasitic element 380. The second end 345 of the fourth radiating section 340 is an open end and is opposite to the first parasitic element 360, and the third radiating section 330 and the fourth radiating section 340 form an L-shaped appearance.

The first end 361 of the first parasitic element 360 has a first ground end GP1 and the second end 365 of the first parasitic element 360 is an open end and opposite the second end 345 of the fourth radiating section 340. Wherein, based on the resonant path length, the direction of the fourth radiating section 340 relative to the second radiating section (eg, the reference direction DR1), and the direction in which the first end 361 of the first parasitic element 360 extends to the second end 365 thereof The second frequency band, which is operated such that the fourth radiating section 340 is coupled to the first parasitic element 360, is smaller than the first frequency band in which the second radiating section 320 is coupled to the first parasitic element 360.

In addition, the first end 381 of the second parasitic element 380 has one of the first The second ground terminal GP2 is adjacent to the feed point FP, and the second end 385 of the second parasitic element 380 has another second ground terminal GP2. The feed point FP, the first ground point GP1, and the two second ground points GP2 are all on the same side and are arranged in a straight line. The feed point FP is between the first ground point GP1 and the two second ground points GP2. Therefore, the feeding point FP, the first grounding point GP1 and the two second grounding points GP2 of the embodiment can be easily connected to the source of the feeding signal and the grounding surface (or the grounding line, the grounding end, etc.).

On the other hand, in terms of the detailed description of the current path, the first current path is from the first end 311 to the second radiating section 320 of the first radiating section 310, and reaches the first through the first coupling pitch CG1. The first end 361 of the parasitic element 360. The second current path is from the first end 311 of the first radiating section 310 to the third radiating section 330 and the fourth radiating section 340, and is transmitted through the second coupling pitch CG2 via the second of the first parasitic element 360. End 365 reaches first end 361 of first parasitic element 360. In addition, the third current path is from the first end 311 to the third radiating section 330 of the first radiating section 310 and passes through the second parasitic element 380 to the second grounding point GP2 through the third coupling pitch CG3. Wherein, the first interval, the second interval and the third interval are between 0.8 mm (mm) and 1.2 mm.

Moreover, the radiating element 300 can further include a matching element 390. The first end 391 of the matching component 390 is electrically coupled to the first end 321 of the second radiating section 320 and/or the second end 315 of the first radiating section 310, from the first end 321 of the second radiating section 320. It extends toward the reference direction DR2 and thereby impedance matches the radiating element 300. Wherein, the reference direction DR2 is opposite to the direction in which the first end 321 of the second radiating section 320 faces the second end 325 of the second radiating section 320 (eg, the reference direction DR1) in contrast. Thereby, the characteristic parameters such as the bandwidth, the frequency or the radiation benefit of the first frequency band or the second frequency band can be finely fine-tuned through the matching component 390.

It should be noted that, according to design requirements, the characteristic parameters (eg, bandwidth, gain, or radiation) of the multi-band antenna 30 can be adjusted through changes in the shape of the radiating element 300, the first parasitic element 360, and the second parasitic element 380. The efficiency and the like) are not limited in the embodiment of the present invention.

In the foregoing embodiment, the first parasitic element 360, the second parasitic element 380, and the radiating element 300 are all located in the same plane (for example, an X-Y plane, an X-Z plane, etc.). In other words, the multi-band antenna 30 has a planar structure and can be simultaneously disposed on one surface of the substrate, for example, a printed circuit board or a Flexible Printed Circuit Board (FPCB). In another embodiment, a portion of the first parasitic element, a portion of the second parasitic element, and a portion of the radiating element are located on different planes, as will be described below.

6A and 6B are schematic diagrams showing the structure of a multi-band antenna according to another embodiment of the present invention. 6A and 6B, the multi-band antenna 60 includes a radiating element 600, a first parasitic element 660, and a second parasitic element 680. The radiating element 300 has a first radiating section 610, a second radiating section 620, a third radiating section 630 and a fourth radiating section 640. The first parasitic element 660 and the second radiating section 620 have a first coupling pitch CG4. The first parasitic element 660 and the fourth radiating section 640 have a second coupling pitch CG5. The second parasitic element 680 has two second ground points GP2. The second parasitic element 680 has a third coupling pitch CG6 between the third radiating section 630.

Radiation element 600, first parasitic element 660, second parasitic element 680, The first coupling pitch CG4, the second coupling pitch CG5, and the third coupling pitch CG6 may correspond to the radiating element 300, the first parasitic element 360, the second parasitic element 380, the first coupling pitch CG1, and the second coupling pitch of FIG. 3, respectively. CG2 and the third coupling pitch CG3, and the detailed structure, relative position, current path and connection manner are referred to the relevant descriptions of FIG. 3 and FIG. 4, and details are not described herein again. The difference from FIG. 3 is that one or a combination of a portion of the first parasitic element 660, a portion of the second parasitic element 680, or a portion of the radiating element 600 is located on a different plane based on the design requirements of the hardware mechanism.

Specifically, please refer to FIG. 6A firstly, firstly, in order to facilitate the connection of the feed point FP, the first ground point GP1 and the two second ground points GP2 with the feed signal source end and the ground plane (or ground line), the feed The in point FP, the first grounding point GP1, and the two second grounding points GP2 may be disposed on the first plane 601 (eg, toward the XZ plane of the -Y axis). The first radiating section 610, the second radiating section 620, the third radiating section 630 and the fourth radiating section of the radiating element 600, a portion of the first parasitic element 660 and a portion of the second parasitic element 680 are disposed. In the second plane 602 (eg, toward the XY plane of the Z axis). Referring to FIG. 6B, a portion of the first parasitic element 660 can be bent such that a portion of the first parasitic element 660 is disposed on the third plane 603 (eg, the XZ plane toward the Y-axis) and/or the fourth plane 604. (for example, the XY plane toward the -Z axis). In other words, the multi-band antenna 60 has a three-dimensional structure and can be simultaneously disposed on a stereoscopic substrate (for example, a rectangular parallelepiped or the like). Thereby, the hardware space consumed by the multi-band antenna 60 can be further reduced, and the development of the antenna miniaturization can be facilitated.

It should be noted that the first parasitic element (for example, the first parasitic element 360 of FIG. 3, the first parasitic element 660 of FIGS. 6A and 6B) and the second parasitic element Or (eg, second parasitic element 380 of FIG. 3, second parasitic element 680 of FIGS. 6A and 6B) and radiating element (eg, radiating element 300 of FIG. 3, radiating element 600 of FIGS. 6A and 6B) are The metal layer on the metal layer of the printed circuit board is etched. In other embodiments, the foregoing structures of FIG. 3 and FIG. 6 may also use a flexible printed circuit board with a plastic carrier or a stamping or any other material or component of the constructed antenna. limit. In addition, the multi-band antenna 30 of FIG. 3 and the multi-band antenna 60 of FIG. 6 can be applied to a wireless device having a mobile communication module such as a mobile phone, a tablet, or a notebook computer.

In summary, the multi-band antenna of the embodiment of the present invention can be adapted for internal use on a general electronic device, and has a wide bandwidth, so that the antenna can work in a wider frequency band (700 MHz). 2600MHZ). Wherein, the capacitive coupling effect is respectively generated by the radiating element and the first parasitic element and the second parasitic element, so that the multi-band antenna can be operated in the first frequency band between the 1700 frequency band and the 2100 frequency band, and the first frequency band between the 700 frequency band and the 900 frequency band The second frequency band and the third frequency band between the 2300 frequency band and the 2600 frequency band further reach all eight frequency bands used by the LTE technology. However, the capacitive coupling method used in the embodiment of the present invention can be adjusted to a larger bandwidth, a higher radiation efficiency, and an easier broadband implementation than a planar inverted-F antenna (PIFA) type. In addition, in the embodiment of the present invention, a part of the radiating element, the first parasitic element and the second parasitic element are disposed on the same or different planes of the three-dimensional substrate, thereby improving the elasticity of the antenna design.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art without departing from the invention. In the spirit and scope, the scope of protection of the present invention is subject to the definition of the appended patent application.

60‧‧‧Multi-band antenna

600‧‧‧radiation components

610‧‧‧First Radiation Section

620‧‧‧second radiation section

630‧‧‧ Third Radiation Section

640‧‧‧fourth radiation section

660‧‧‧First parasitic element

680‧‧‧Second parasitic element

690‧‧‧Matching components

601‧‧‧ first plane

602‧‧‧ second plane

CG4‧‧‧First coupling spacing

CG5‧‧‧second coupling spacing

CG6‧‧‧ third coupling spacing

FP‧‧‧Feeding point

GP1‧‧‧first grounding point

GP2‧‧‧second grounding point

Claims (9)

A multi-band antenna comprising: a radiating element having a first radiating section, a second radiating section, a third radiating section and a fourth radiating section; a first parasitic element having a first a grounding point, wherein the first parasitic element and the second radiating section have a first coupling pitch, and operate through a first frequency band through the first radiating section and the second radiating section, and the first a parasitic element and the fourth radiating section have a second coupling pitch, and operate in a second frequency band through the first radiating section, the third radiating section and the fourth radiating section; and a a second parasitic element having two second grounding points, wherein the second parasitic element and the second grounding points form a "ㄇ"-shaped appearance, and the second parasitic element and the third radiating section have a a third coupling pitch, and operating through a first frequency band and the third radiation segment in a third frequency band, wherein the first end of the first radiation segment has a feed point, the first radiation segment The second end is electrically connected to the first end of the second radiating section Connecting, the second end of the second radiating section is an open end, one side of the second radiating section is opposite to the first parasitic element, and the first radiating section and the second radiating section are configured An L-shaped appearance, wherein the first end of the third radiating section is electrically coupled to one side of the first radiating section, and the first end of the third radiating section is from the first radiating section a side edge extending in a vertical direction, a second end of the third radiating section and a fourth end of the fourth radiating section One end is electrically connected, one side of the third radiating section is opposite to the second parasitic element, and the other side of the third radiating section is opposite to the second radiating section, the fourth radiating section The second end is an open end and opposite to the first parasitic element, and the third radiating section and the fourth radiating section form an L-shaped appearance. The multi-band antenna of claim 1, wherein the first end of the first parasitic element has the first ground end, and the second end of the first parasitic element is an open end and opposite to the first a second end of the fourth radiating section, wherein the first end of the second parasitic element has one of the second ground ends adjacent to the feed point, and the second end of the second parasitic element has the The other of the second ground terminals. The multi-band antenna of claim 1, wherein the multi-band antenna forms a first current path through the first radiating section, the second radiating section and the first parasitic element, and the first current path is transmitted through the first The radiation section, the third radiation section, the fourth radiation section, and the first parasitic element form a second current path, and pass through the first radiation section, the third radiation section, and the second parasitic The component forms a third current path, wherein the length of the third current path is less than the length of the first current path, and the length of the first current path is less than the length of the second current path. The multi-band antenna according to claim 1, wherein the first frequency band is between the 1700 (million Hz; MHz) frequency band and the 2100 MHz frequency band, and the second frequency band is between the 700 MHz frequency band and the 900 MHz frequency band. And the third frequency band is between the 2300MHz frequency band and the 2600MHz frequency band. The multi-band antenna of claim 1, wherein the feed point, the first ground point, and the second ground point are all on the same side and are arranged in a straight line. The multi-band antenna of claim 1, wherein the first coupling pitch, the second coupling pitch, and the third coupling pitch are between 0.8 millimeters (mm) and 1.2 millimeters. The multi-band antenna of claim 1, wherein the first parasitic element, the second parasitic element, and the radiating element are all located in the same plane. The multi-band antenna of claim 1, wherein a portion of the first parasitic element, a portion of the second parasitic element, and a portion of the radiating element are located in different planes. The multi-band antenna of claim 1, wherein the first parasitic element, the second parasitic element or the radiating element is etched from a metal layer on a metal layer of a printed circuit board.