阅读说明：本技术 电子装置及其多频段柔性电路板天线结构 (electronic device and multi-band flexible circuit board antenna structure thereof ) 是由 李谟霖 郭加弘 洪国瀛 于 2018-06-06 设计创作，主要内容包括：本发明公开一种电子装置及其多频段柔性电路板天线结构,多频段柔性电路板天线结构包括一第一基板层、一第一金属层、一第二基板层以及一第二金属层。第一基板层包括一第一树脂层,第一金属层形成于第一树脂层上,以构成一第一天线。第二基板层与第一基板层呈堆栈设置,且包括一第二树脂层,第二金属层形成于第二树脂层上,以构成一第二天线。第一天线与第二天线在一垂直方向上的投影不重合,第一树脂层与第二树脂层具有不同的介电系数,以使第一天线与第二天线具有不同的频段。借此,可以兼顾微型化与多种天线功能的设计要求。(The invention discloses an electronic device and a multi-band flexible circuit board antenna structure thereof. The first substrate layer comprises a first resin layer, and the first metal layer is formed on the first resin layer to form a first antenna. The second substrate layer and the first substrate layer are stacked and comprise a second resin layer, and the second metal layer is formed on the second resin layer to form a second antenna. The projections of the first antenna and the second antenna in a vertical direction are not overlapped, and the first resin layer and the second resin layer have different dielectric coefficients, so that the first antenna and the second antenna have different frequency bands. Therefore, design requirements of miniaturization and multiple antenna functions can be met.)

1. A multi-band flexible circuit board antenna structure, comprising:

A first substrate layer comprising a first resin layer;

A first metal layer formed on the first resin layer to form a first antenna;

The second substrate layer and the first substrate layer are stacked and comprise a second resin layer; and

The second metal layer is formed on the second resin layer to form a second antenna;

The projections of the first antenna and the second antenna in a vertical direction are not overlapped, and the first resin layer and the second resin layer have different dielectric coefficients, so that the first antenna and the second antenna have different frequency bands.

2. The multi-band flexible circuit board antenna structure of claim 1, wherein said multi-band flexible circuit board antenna has a first slot and a second slot, said first slot is located corresponding to said second antenna and said first slot penetrates said first substrate layer and said first metal layer, said second slot is located corresponding to said first antenna and said second slot penetrates said second substrate layer and said second metal layer.

3. The multi-band flexible circuit board antenna structure of claim 1, wherein said first substrate layer further comprises a first core layer, and said first resin layer and said first metal layer are formed on opposite surfaces of said first core layer, respectively, said second substrate layer further comprises a second core layer, and said second resin layer and said second metal layer are formed on opposite surfaces of said second core layer, respectively.

4. The multi-band flexible circuit board antenna structure according to claim 1, wherein the material of the first resin layer and the second resin layer comprises a modified liquid crystal polymer, a modified polyimide or a modified epoxy resin, the modified liquid crystal polymer, the modified polyimide and the modified epoxy resin have a modifying functional group, and the modifying functional group is an amine group, an amide group, an imine group, an amidine group, an aminocarbonylamine group, an aminothiocarbonyl group, an aminocarbonyloxy group, an aminosulfonyl group, an aminosulfonyloxy group, a carboxylate ester, a carboxylate amine group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an alkoxyamino group, a hydroxyamine group, a cyanamide group or an isocyanate group.

5. The multi-band flexible circuit board antenna structure of claim 2, further comprising a third substrate layer formed between the first substrate layer and the second substrate layer and a third metal layer formed on the third substrate layer and electrically connected to the first metal layer and the second metal layer.

6. The multiple band flexible circuit board antenna structure of claim 5, wherein said first metal layer comprises a first radiating portion and a first connecting portion connected to said first radiating portion, said second metal layer comprises a second radiating portion and a second connecting portion connected to said second radiating portion, and said first connecting portion and said second connecting portion are electrically connected to said third metal layer.

7. The multi-band flexible circuit board antenna structure of claim 6, further comprising a first conductive pillar and a second conductive pillar, wherein the first conductive pillar penetrates the first substrate layer, and both ends of the first conductive pillar contact the first connection portion and the third metal layer of the first metal layer, respectively, the second conductive pillar penetrates the second substrate layer and the third substrate layer, and both ends of the second conductive pillar contact the second connection portion and the third metal layer of the second metal layer, respectively.

8. The multi-band flexible circuit board antenna structure of claim 2, further comprising a third substrate layer and a third metal layer, wherein the second substrate layer and the second metal layer are formed on one surface of the third substrate layer, the first substrate layer and the first metal layer are formed on the second metal layer, and the third metal layer is formed on the opposite surface of the third substrate layer and is electrically connected to the first metal layer and the second metal layer.

9. The multiple band flexible circuit board antenna structure of claim 8, wherein said first metal layer comprises a first radiating portion and a first connecting portion connected to said first radiating portion, said second metal layer comprises a second radiating portion and a second connecting portion connected to said second radiating portion, and said first connecting portion and said second connecting portion are electrically connected to said third metal layer.

10. The multi-band flexible circuit board antenna structure of claim 9, further comprising a first conductive pillar and a second conductive pillar, wherein the first conductive pillar penetrates through the first substrate layer, the second substrate layer and the third substrate layer, and both ends of the first conductive pillar contact the first connection portion and the third metal layer of the first metal layer, respectively, the second conductive pillar penetrates through the second substrate layer and the third substrate layer, and both ends of the second conductive pillar contact the second connection portion and the third metal layer of the second metal layer, respectively.

11. An electronic device characterized in that it uses the multiband flexible circuit board antenna structure according to any one of claims 1 to 10.

Technical Field

The present invention relates to an antenna and an electronic device using the same, and more particularly, to an antenna structure of a multi-band flexible printed circuit board and an electronic device using the same.

Background

With the development of communication technology, the functional requirements of electronic devices (such as smart phones, tablet computers, notebook computers, etc.) are becoming more diversified, for example, the electronic devices need to support communication functions such as Near Field Communication (NFC), GPS, 3G, WIFI, bluetooth, etc. Therefore, an antenna needs to be installed in the electronic device to transmit and receive signals. However, while the electronic device is designed toward miniaturization, the internal space of the electronic device greatly limits the design of the antenna, and the most direct effect is that the electronic device cannot be operated in a plurality of different frequency bands.

In addition, in subtropical areas with high temperature and high humidity in China, once a high-frequency signal is transmitted under the environment condition of high temperature and high humidity, variation may be generated and the integrity of the signal is influenced. Moreover, the substrate of the existing printed circuit board is structurally composed, so that low dielectric loss is difficult to achieve at the frequency of 10GHz, and high temperature resistance and low moisture absorption performance are not considered at the same time.

therefore, there is a need for a multifunctional antenna that not only has multiple frequency bands, but also overcomes the limitation of the limited space inside the electronic device, and ensures the transmission quality and stability of high-frequency signals under severe environmental conditions.

Disclosure of Invention

The invention provides a multi-band flexible circuit board antenna structure aiming at the defects of the prior art, and aims to solve the problems that the antenna function is single and the internal space of an electronic device cannot be fully utilized. Also, an electronic device using the multi-band flexible circuit board antenna structure is provided.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is: a multi-band flexible circuit board antenna structure comprises a first substrate layer, a first metal layer, a second substrate layer and a second metal layer. The first substrate layer comprises a first resin layer, and the first metal layer is formed on the first resin layer to form a first antenna. The second substrate layer and the first substrate layer are stacked and comprise a second resin layer, and the second metal layer is formed on the second resin layer to form a second antenna. The projections of the first antenna and the second antenna in a vertical direction are not overlapped, and the first resin layer and the second resin layer have different dielectric coefficients, so that the first antenna and the second antenna have different frequency bands.

Furthermore, the multi-band flexible circuit board antenna has a first slot and a second slot, the first slot is corresponding to the second antenna, the first slot penetrates through the first substrate layer and the first metal layer, the second slot is corresponding to the first antenna, and the second slot penetrates through the second substrate layer and the second metal layer.

Further, the first substrate layer further includes a first core layer, and the first resin layer and the first metal layer are respectively formed on two opposite surfaces of the first core layer, and the second substrate layer further includes a second core layer, and the second resin layer and the second metal layer are respectively formed on two opposite surfaces of the second core layer.

further, the material of the first resin layer and the second resin layer comprises a modified liquid crystal polymer, a modified polyimide or a modified epoxy resin, the modified liquid crystal polymer, the modified polyimide and the modified epoxy resin have a modified functional group, and the modified functional group is an amino group, an amide group, an imine group, an amidino group, an aminocarbonylamino group, an aminothiocarbonyl group, an aminocarbonyloxy group, an aminosulfonyl group, an aminosulfonyloxy group, a carboxylic ester amino group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an alkoxyamino group, a hydroxylamino group, a cyanamide group or an isocyanate group.

Furthermore, the multi-band flexible circuit board antenna further comprises a third substrate layer and a third metal layer, wherein the third substrate layer is formed between the first substrate layer and the second substrate layer, and the third metal layer is formed on the third substrate layer and is electrically connected with the first metal layer and the second metal layer.

furthermore, the first metal layer includes a first radiation portion and a first connection portion connected to the first radiation portion, the second metal layer includes a second radiation portion and a second connection portion connected to the second radiation portion, and the first connection portion and the second connection portion are electrically connected to the third metal layer.

Furthermore, the multi-band flexible circuit board antenna further comprises a first conductive column and a second conductive column, the first conductive column penetrates through the first substrate layer, two ends of the first conductive column are respectively contacted with the first connecting portion and the third metal layer of the first metal layer, the second conductive column penetrates through the second substrate layer and the third substrate layer, and two ends of the second conductive column are respectively contacted with the second connecting portion and the third metal layer of the second metal layer.

Furthermore, the multi-band flexible circuit board antenna further comprises a third substrate layer and a third metal layer, wherein the second substrate layer and the second metal layer are formed on one surface of the third substrate layer, the first substrate layer and the first metal layer are formed on the second metal layer, and the third metal layer is formed on the other surface of the third substrate layer opposite to the first metal layer and is electrically connected with the first metal layer and the second metal layer.

Furthermore, the first metal layer includes a first radiation portion and a first connection portion connected to the first radiation portion, the second metal layer includes a second radiation portion and a second connection portion connected to the second radiation portion, and the first connection portion and the second connection portion are electrically connected to the third metal layer.

Furthermore, the multi-band flexible circuit board antenna further comprises a first conductive column and a second conductive column, the first conductive column penetrates through the first substrate layer, the second substrate layer and the third substrate layer, two ends of the first conductive column are respectively contacted with the first connecting portion and the third metal layer of the first metal layer, the second conductive column penetrates through the second substrate layer and the third substrate layer, and two ends of the second conductive column are respectively contacted with the second connecting portion and the third metal layer of the second metal layer.

In order to solve the above technical problem, another technical solution adopted by the present invention is: an electronic device using the multi-band flexible circuit board antenna structure.

One of the benefits of the electronic device and the multi-band flexible circuit board antenna structure provided by the invention is that the electronic device and the multi-band flexible circuit board antenna structure provided by the invention can make multiple antennas with different frequency bands on different board layers of the same flexible circuit board through the technical schemes of 'the projection of the second metal layer is not overlapped with the projection of the first metal layer in the vertical direction' and 'the first resin layer and the second resin layer have different dielectric coefficients', so that the structure of the multi-in-one antenna is realized, the internal space of the electronic device can be fully utilized, and the design of more functions of the product is facilitated.

For a better understanding of the features and technical content of the present invention, reference should be made to the following detailed description and accompanying drawings, which are provided for purposes of illustration and description only and are not intended to limit the invention.

Drawings

FIG. 1 is a schematic top view of the multi-band flexible circuit board antenna structure of the present invention.

FIG. 2 is a schematic cross-sectional view of the multi-band flexible circuit board antenna structure of FIG. 1 along the I-I section line.

FIG. 3 is another cross-sectional view of the multi-band flexible circuit board antenna structure of FIG. 1 along section line I-I.

FIG. 4 is a schematic diagram of an electronic device of the multi-band flexible circuit board antenna structure according to the present invention.

Detailed Description

Because the Flexible Printed Circuit (FPC) has the advantages of being capable of being bent freely and being arranged freely according to the space layout requirement and the like in use, the invention realizes the design of the all-in-one antenna by utilizing the FPC so as to meet various functional requirements of electronic products.

The following is a description of the embodiments of the present disclosure related to "electronic device and multi-band flexible circuit board antenna structure thereof" by specific embodiments, and those skilled in the art can understand the advantages and effects of the present disclosure from the disclosure of the present disclosure. The invention is capable of other and different embodiments and its several details are capable of modification and various other changes, which can be made in various details within the specification and without departing from the spirit and scope of the invention. The drawings of the present invention are for illustrative purposes only and are not intended to be drawn to scale. The following embodiments will further explain the related art of the present invention in detail, but the disclosure is not intended to limit the scope of the present invention.

It will be understood that, although the terms "first," "second," "third," etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are used primarily to distinguish one element from another element or from one signal to another signal. In addition, the term "or" as used herein should be taken to include any one or combination of more of the associated listed items as the case may be.

First embodiment

Referring to fig. 1 and fig. 2, a multi-band flexible circuit board antenna structure B is provided in a first embodiment of the present invention, in which at least two different frequency bands of antennas are formed on different board layers of a same flexible circuit board, so as to meet the diversity of the antenna function requirements of an electronic device. The multi-band flexible circuit board antenna structure B uses a multilayer wiring board, which at least includes a first substrate layer 1, a first metal layer 2, a second substrate layer 3, a second metal layer 4, a third substrate layer 5 and a third metal layer 6 stacked.

The first metal layer 2 is formed on the first substrate layer 1 and has a predetermined antenna pattern, so that the first metal layer 2 and the first substrate layer 1 may form a first antenna a 1. The second metal layer 4 is formed on the second substrate layer 3 and has another predetermined antenna pattern, so that the second metal layer 4 and the second substrate layer 3 can form a second antenna a 2. To avoid the mutual interference between the first antenna a1 and the second antenna a2, the multi-band flexible circuit board antenna structure B may have a first slot S1 corresponding to the second antenna a2 and a second slot S2 corresponding to the first antenna a 1. The first slot S1 at least penetrates through the first substrate layer 1 and the first metal layer 2, and the second slot S2 at least penetrates through the second substrate layer 3 and the second metal layer 4, so that the projections of the first metal layer 2 and the second metal layer 4 in a vertical direction are not overlapped.

Further, the first substrate layer 1 includes a first core layer 11 and a first resin layer 12, and the first resin layer 12 and the first metal layer 2 are respectively formed on two opposite surfaces of the first core layer 11. The second substrate layer 3 includes a second core layer 31 and a second resin layer 32, and the second resin layer 32 and the second metal layer 4 are respectively formed on two opposite surfaces of the second core layer 31. It should be noted that, in the structure in which the first antenna a1 and the second antenna a2 are respectively formed on different board layers, the dielectric coefficients of the first resin layer 12 and the second resin layer 32 can be controlled to perform various combinations according to the requirements of the electronic device for the antenna functions, that is, when the first resin layer 12 and the second resin layer 32 have different dielectric coefficients, the first antenna a1 and the second antenna a2 can have different frequency bands. For example, the first antenna a1 may be one of a GPS antenna, an NFC antenna, a bluetooth antenna, and a wifi antenna, and the second antenna a2 may be another one of a GPS antenna, an NFC antenna, a bluetooth antenna, and a wifi antenna. However, the above-mentioned examples are only one possible embodiment and are not intended to limit the present invention.

In the present embodiment, the thicknesses of the first resin layer 12 and the second resin layer 32 can be adjusted according to the matching bandwidth required by the antenna, and the thicknesses of the first resin layer 12 and the second resin layer 32 can be between 12 μm and 105 μm, but are not limited thereto. The first resin layer 12 and the second resin layer 32 may have a single-layer or multi-layer structure. The material of the first and second resin layers 12 and 32 may include a fluororesin, a polyphenylene oxide resin (PPO/PPE), an aralkyl type epoxy resin, or any combination thereof. As the fluororesin, Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE) can be used. As the aralkyl type epoxy resin, a biphenyl type epoxy resin can be used.

The material of the first resin layer 12 and the second resin layer 32 preferably includes modified liquid crystal polymer (modified LCP), modified polyimide (modified PI), or modified epoxy (modified epoxy), but is not limited thereto. The thickness of the first metal layer 2 and the second metal layer 4 may be between 2 μm and 105 μm, but is not limited thereto. The material of the first metal layer 2 and the second metal layer 4 may be a highly conductive metal such as copper, nickel, silver, gold, or an alloy thereof, but is not limited thereto.

In addition, ceramic powder may be used as needed for the first resin layer 12 and the second resin layer 32. The proportion of the ceramic powder in the first resin layer 12 or the second resin layer 32 may be between 40 wt% and 70 wt%, preferably between 25 wt% and 35 wt%.

Further, the modified liquid crystal polymer, the modified polyimide, or the modified epoxy resin may have at least one modifying functional group, which may be, but is not limited to, an amine group (amino), an amide group (carboxamido), an imine group (imino or imino), an amidino group (amidino), an aminocarbonylamine group (aminocarbonylamino), an aminothiocarbonyl group (aminothiocarbonyl), an aminocarbonyloxy group (aminocarbonyloxy), an aminosulfonyl group (aminosulfonyl), an aminosulfonyloxy group (aminosulfonyloxy), a carboxylate group (carboxyl ester), a carboxylate amine group (carboxyl ester) amino, an alkoxycarbonyl group (alkoxycarbonyl), an alkoxycarbonyloxy group (alkoxycarbonyloxy), an alkoxyamine group (alkoxyamino), a hydroxyamine group (hydroxyamino), a cyanamide group (cyanato), or an isocyanato group (isocyanato).

The modified liquid crystal polymer, the modified polyimide and the modified epoxy resin may be applied to one surface of the first core layer 11 or the second core layer 31 together with a specific solvent, and then the specific solvent is removed to form the first resin layer 12 or the second resin layer 32. It is noted that the modified liquid crystal polymer, the modified polyimide and the modified epoxy resin have higher solubility in a specific solvent than before being modified, so that the processability can be improved. Specific examples of the specific solvent include: n-methyl-2-pyrrolidone (NMP), Dimethylacetamide (DMAC), Dimethylformamide (DMF), gamma-butyrolactone (GBL), 2-butoxyethanol, 2-ethoxyethanol, and the like. The solid content of the modified liquid crystal polymer, modified polyimide, or modified epoxy resin in the material of the first resin layer 12/the second resin layer 32 may be between 1 wt% and 85 wt%, such as 5 wt%, 15 wt%, 25 wt%, 35 wt%, 45 wt%, 55 wt%, 65 wt%, or 75 wt%.

Furthermore, since the first resin layer 12 and the second resin layer 32 are made of modified liquid crystal polymer, modified polyimide or modified epoxy resin, the water absorption of the first resin layer 12 and the second resin layer 32 can be reduced to less than 0.8%, which is much less than the water absorption (about 2%) of the resin layers used in the related art, so that the multi-band flexible circuit board antenna structure B can adapt to a severe high-humidity environment, that is, the multi-band flexible circuit board antenna structure B can still be used normally even under a high-humidity environment.

In addition, the material of the first resin layer 12 or the second resin layer 32 may be used in combination with one or more additives as necessary. The additive may be selected from one or a combination of two or more of high dielectric fillers, inorganic fillers, organic fillers, whiskers (whisker), silane coupling agents, antioxidants, and ultraviolet absorbers, but is not limited thereto. Barium titanate and strontium titanate can be used as the high dielectric filler. As the inorganic filler, silica, aluminum hydroxide, and calcium carbonate can be used. As the organic filler, a cured epoxy resin, a benzoguanamine resin, and an acrylic polymer can be used. As the whiskers, potassium titanate and aluminum borate can be used. However, the present invention is not limited to the above-mentioned examples.

In the present embodiment, the thickness of the first core layer 11 and the second core layer 31 may be between 8 μm and 200 μm, but is not limited thereto. The materials of the first core layer 11 and the second core layer 31 are preferably the same as the materials of the first resin layer 12 and the second resin layer 32, that is, the materials of the first core layer 11 and the second core layer 31 may include fluorine resin, polyphenylene oxide resin (PPO/PPE), aralkyl type epoxy resin or any combination thereof, and specific examples thereof are as described above and will not be described herein again. Moreover, the materials of the first core layer 11 and the second core layer 31 preferably include a modified liquid crystal polymer, a modified polyimide or a modified epoxy resin, which has at least one modifying functional group, as mentioned above, and thus are not described herein again.

Referring to fig. 2 again, the third substrate layer 5 is formed between the first substrate layer 1 and the second substrate layer 3, the third metal layer 6 is formed on a surface of the third substrate layer 5 and has a predetermined circuit pattern, and the first metal layer 2 and the second metal layer 4 are electrically connected to the third metal layer 6, so that the third metal layer 6 can form a signal transmission line, and in practical use, the first antenna a1 and the second antenna a2 on opposite sides thereof can be controlled by the third metal layer 6 in a combined manner.

Further, the first metal layer 2 includes a first radiation portion 21 and a first connection portion 22 connected to the first radiation portion 21, wherein the first connection portion 22 may be electrically connected to the third metal layer through a first conductive pillar P1 penetrating through the first substrate layer 1. The second metal layer 4 includes a second radiation portion 41 and a second connection portion 42 connected to the second radiation portion 41, wherein the second connection portion 42 can be electrically connected to the third metal layer 6 through a second conductive pillar P2 penetrating through the second substrate layer 3.

It should be noted that another fourth metal layer 7 may be formed on the other surface of the third substrate layer 5, and the fourth metal layer 7 has another predetermined circuit pattern, so as to meet the requirements of more complicated circuit design and function.

In the present embodiment, the third substrate layer 5 mainly plays a role of bearing and supporting, and the thickness of the third substrate layer 5 may be between 8 μm and 200 μm, but is not limited thereto. The material of the third substrate layer 5 is preferably the same as the material of the first resin layer 12 and the second resin layer 32, that is, the material of the third substrate layer 5 preferably comprises a modified liquid crystal polymer, a modified polyimide or a modified epoxy resin, which has at least one modifying functional group, as described above, and will not be described herein again. The thickness of the third metal layer 6 and the fourth metal layer 7 may be between 2 μm and 105 μm, but is not limited thereto. The material of the third metal layer 6 and the fourth metal layer 7 may be a highly conductive metal such as copper, nickel, silver, gold, or an alloy thereof, but is not limited thereto.

Second embodiment

Referring to fig. 3, a second embodiment of the present invention provides a multi-band flexible circuit board antenna structure B, in which at least two different frequency bands of antennas are formed on different board layers of the same flexible circuit board, so as to meet the diversity of the antenna function requirements of an electronic device. The multi-band flexible circuit board antenna structure B is a multi-layer wiring board, which at least comprises a first substrate layer 1, a first metal layer 2, a second substrate layer 3, a second metal layer 4, a third substrate layer 5 and a third metal layer 6 which are stacked. For details of the first, second and third substrate layers 1, 3, 5 and the first, second and third metal layers 2, 4, 6, reference may be made to the description of the first embodiment, which is not repeated herein.

The main difference between this embodiment and the first embodiment is: the first antenna a1 and the second antenna a2 are both located above the third substrate layer 5. Further, the second substrate layer 3 and the second metal layer 4 are formed on one surface of the third substrate layer 5, the first substrate layer 1 and the first metal layer 2 are formed on the second metal layer 4, and the third metal layer 6 is formed on the other surface of the third substrate layer 5. The first connection portion 22 of the first metal layer 2 may be electrically connected to the third metal layer 6 through a first conductive pillar P1 penetrating through the first, second and third substrate layers 1, 3 and 5, and the second connection portion 42 of the second metal layer 4 may be electrically connected to the third metal layer 6 through a second conductive pillar P2 penetrating through the second and third substrate layers 3 and 5.

Third embodiment

Referring to fig. 4, the present invention further provides an electronic device D using the multi-band flexible circuit board antenna structure B. Further, the electronic device D includes a control unit C, and a first antenna a1, a second antenna a2, a third antenna A3 and a fourth antenna a4 of different frequency bands. The control unit C may be any kind of processor or programmable circuit. The first antenna a1, the second antenna a2, the third antenna A3 and the fourth antenna a4 are located on different board layers and are all electrically connected to a signal transmission line L. Thus, the control unit C can perform combined control on the first antenna a1, the second antenna a2, the third antenna A3 and the fourth antenna a4 through the signal transmission line L, and switch to different frequency bands as required to meet different communication requirements.