High isolation broadband antenna system

Abstract

The present invention provides a high-isolation broadband antenna system. On the one hand, by setting a first metal branch node and a metal structural member to be electrically connected and grounded together, the electrical length thereof is effectively increased, low-frequency resonance is achieved, and then the resonance in the middle and high frequency bands is achieved in combination with the second metal branch node. On the other hand, by setting a third metal branch node and a fourth metal branch node with an asymmetric structure, and making the third metal branch node electrically connected to the grounding wire of the second coaxial line, the electrical length thereof is effectively increased, low-frequency resonance is achieved, and then the resonance in the middle and high frequency bands is achieved in combination with the fourth metal branch node. Furthermore, the third metal branch node and the fourth metal branch node are not directly electrically connected to the metal structural member, thereby improving the isolation between the two antenna structures. Finally, the first coaxial line and the second coaxial line are arranged as a "Y"-shaped routing, thereby further reducing the influence of the first coaxial line on the current on the grounding wire of the second coaxial line, thereby ensuring the simplicity of wiring and further improving the isolation between the two antenna structures.

Description

Technical Field

[0001] The invention belongs to the field of antenna structure design, and in particular relates to a high-isolation broadband antenna system. Background Art

[0002] In recent years, in-vehicle wireless communication systems have become increasingly important for automobiles, such as cellular network communications, global positioning systems and other wireless communications in-vehicle applications. As an important part of the wireless communication system, the antenna system plays a vital role. With the development of new technologies, the integration and miniaturization of antenna systems will be the trend of future design. In particular, the development of 5G technology has brought many new innovations and changes, such as the addition of multiple frequency bands such as 600M low frequency in the spectrum, and the popularization of multi-antenna MIMO technology. As a result, in a small space, the integrated design of multiple, wide-band antennas has become the mainstream of antenna system design in the future, but it also brings challenges to antenna design: broadband antennas, isolation requirements between multiple antennas (especially low-frequency bands), etc. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a high-isolation broadband antenna system for solving the problem in the prior art that it is difficult to integrate a large number of broadband antennas in a small space.

[0004] To achieve the above-mentioned object and other related objects, the present invention provides a high-isolation broadband antenna system, the antenna system comprising:

[0005] A metal structure located at the bottom layer of the box, and a first antenna structure and a second antenna structure located above the metal structure and arranged in pairs, wherein the first antenna structure and the second antenna structure are arranged at intervals along the length direction of the metal structure;

[0006] The first antenna structure includes a first coaxial line and a first metal branch and a second metal branch arranged at intervals along the width direction of the metal structure; wherein the first metal branch includes a first extension portion extending along the width direction of the metal structure and a second extension portion extending in the direction of the metal structure, there is a strong electrical coupling between the first metal branch and the second metal branch, and the expansion area of ​​the first metal branch is greater than the expansion area of ​​the second metal branch, the second extension portion is electrically connected to the metal structure, the signal line of the first coaxial line is electrically connected to the second metal branch, and the ground line of the first coaxial line is electrically connected to the metal structure;

[0007] The second antenna structure includes a second coaxial line and a third metal branch and a fourth metal branch located on the upper surface of the support and spaced apart; the third metal branch and the fourth metal branch are asymmetric structures, and the expansion area of ​​the third metal branch is smaller than the expansion area of ​​the fourth metal branch, the signal line of the second coaxial line is electrically connected to the fourth metal branch, the ground line of the second coaxial line is electrically connected to the third metal branch, and the projections of the third metal branch and the fourth metal branch in the direction of the metal structure all fall on the metal structure and are not electrically connected to the metal structure;

[0008] The routing of the first coaxial line and the second coaxial line is quasi-"Y"-shaped, and the two coaxial lines are wired in parallel with each other after merging at the Y node, wherein the length of the coaxial line is greater than one-fourth of the wavelength corresponding to the lowest operating frequency of the antenna of the antenna structure in which it is located.

[0009] Optionally, the length of the coaxial line from the Y node to the feeding position is not less than one sixth of the wavelength of the medium corresponding to the lowest operating frequency of the antenna of the antenna structure in which it is located.

[0010] Optionally, the second extension portion is electrically connected to the metal structure through at least one of a series and / or parallel inductor, capacitor and switch element.

[0011] Optionally, the second metal branch includes a third extending portion extending along a width direction of the metal structure and a fourth extending portion extending toward the metal structure, and the signal line of the first coaxial line is electrically connected to the fourth extending portion.

[0012] Optionally, the metal structural member has slits and / or holes.

[0013] Optionally, a patch antenna is arranged between the first antenna structure and the second antenna structure.

[0014] Optionally, the antenna system includes two pairs of the first antenna structure and the second antenna structure arranged in pairs and distributed along the length direction of the metal structure.

[0015] Furthermore, the two pairs of the first antenna structure and the second antenna structure are arranged in pairs in a layout manner of: first antenna structure-second antenna structure-second antenna structure-first antenna structure, or first antenna structure-second antenna structure-first antenna structure-second antenna structure.

[0016] Optionally, starting from the feeding position of the second coaxial line, a magnetic ring or a balun structure is sleeved on the outer end of the second coaxial line at a distance of at least one quarter of the wavelength corresponding to the lowest operating frequency of the antenna of the second antenna structure.

[0017] Furthermore, the material used for the magnetic ring has a magnetic permeability of 390-410 and a magnetic loss tangent of 0.4-0.6 at 0.7 GHz.

[0018] Optionally, before the first coaxial line and the second coaxial line meet at the Y node, an insulating clamp is provided to achieve a wiring method in which a certain distance is maintained.

[0019] Optionally, a PCB board is arranged above the metal structural member, the first metal branch node and the second metal branch node are arranged in an insulating area of ​​the PCB board, and the third metal branch node and the fourth metal branch node are formed by processing the metal layer of the PCB board.

[0020] As described above, the high-isolation broadband antenna system of the present invention, on the one hand, by setting the expanded area of ​​the first metal branch node to be larger than the expanded area of ​​the second metal branch node and electrically connected to the metal structural member and grounded together, through the strong coupling effect, the first antenna structure achieves resonance in the low frequency band, and then combines with the second metal branch node with a small expanded area to jointly achieve resonance in the medium and high frequency bands of the first antenna structure, so that the first antenna structure covers a wide-band antenna; on the other hand, by setting the third metal branch node and the fourth metal branch node with an asymmetric structure, which is equivalent to an unbalanced dipole, and the third metal branch node with a smaller expanded area is electrically connected to the ground wire of the second coaxial line, the electrical length of the third metal branch node is effectively increased, so that the second antenna structure achieves resonance in the low frequency band. , combined with the fourth metal branch, the second antenna structure can achieve the resonance of the middle and high frequencies, so that the second antenna structure can be covered as a wide-band antenna; furthermore, the third metal branch and the fourth metal branch are not directly electrically connected to the metal structure, that is, there is no direct electrical connection between the first antenna structure and the second antenna structure, so that in this antenna system, the "reference ground" of the first antenna structure and the second antenna structure is cleverly well isolated, so that the isolation between the two antenna structures is improved; finally, the first coaxial line and the second coaxial line are set as a "Y"-shaped routing, which further reduces the influence of the first coaxial line on the current on the grounding line of the second coaxial line, which not only ensures the simplicity of wiring, but also further improves the isolation between the two antenna structures. In this way, the box antenna system of the present invention solves the problem of integrating more than two wide-band antennas in a narrow space while meeting the isolation, especially the isolation of the low-frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a structural schematic diagram of a high-isolation broadband antenna system according to Embodiment 1 of the present invention.

[0022] Figure 2 Display as Figure 1 Schematic diagram of the enlarged structure at point A in the middle.

[0023] Figure 3 Display as Figure 1 Schematic diagram of the enlarged structure at point B in the middle.

[0024] Figure 4 The figure shows the simulated S parameters (isolation and return loss) of Example 1.

[0025] Figure 5 Shown is the simulation efficiency diagram of Example 1.

[0026] Figure 6 It shows the simulation current result diagram of the entire antenna system when the second antenna structure in the high-isolation broadband antenna system of Example 2 is added with a magnetic ring and when the magnetic ring is not added.

[0027] Figure 7 It shows a comparison diagram of the simulation efficiency of the entire antenna system when the second antenna structure of Example 2 is added with a magnetic ring and when the second antenna structure is not added with a magnetic ring.

[0028] Figure 8 Shown is a schematic structural diagram of a high-isolation broadband antenna system according to Embodiment 3 of the present invention.

[0029] Fig. 9 The actual return loss diagram of Example 3 is shown.

[0030] Fig.10 Shown is the actual isolation diagram of Example 3.

[0031] Fig.11 Shown is the simulation efficiency diagram of Example 3.

[0032] Component number description

[0033] 10 Box 11 Lid 12 Metal structural parts 13 PCB board 14 The first coaxial line 141 The signal line of the first coaxial line 142 Ground wire of the first coaxial line 15 First Metal Section 151 First extension 152 The second extension 16 Second Metal Section 161 The third extension 162 Fourth extension 17 The second coaxial line 171 The signal line of the second coaxial line 172 Ground wire of the second coaxial line 18 Third Metal Section 19 The fourth metal branch 20 Y Node 21 Magnetic ring 22 Insulation clip 23 Insulation layer 24 inductance DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] See also Figures 1 to 11 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed according to actual needs, and the component layout type may also be more complicated.

[0036] As mentioned in the background technology, with the development of new technologies, the integration and miniaturization of antenna systems will be the trend of future design, especially the development of 5G technology has brought many new innovations and changes, such as the addition of multiple low frequencies in the spectrum and the popularization of multi-antenna MIMO technology. As a result, it is challenging to integrate multiple, wide-bandwidth antennas in a small space while meeting the isolation requirements (especially in the low-frequency band) to achieve antenna design.

[0037] Based on this, the present invention provides a high-isolation broadband antenna system, which solves the problem of integrating two or more broadband antennas in a small space while satisfying the isolation requirement, especially the isolation requirement in the low-frequency band. Figures 1 to 3 As shown, the high isolation broadband antenna system comprises:

[0038] A metal structure 12 located at the bottom layer of the box 10, and a first antenna structure and a second antenna structure located above the metal structure 12 and arranged in pairs, wherein the first antenna structure and the second antenna structure are arranged at intervals along the length direction of the metal structure 12;

[0039] like Figure 1 and Figure 2 As shown, the first antenna structure includes a first coaxial line 14 and a first metal branch 15 and a second metal branch 16 arranged at intervals along the width direction X of the metal structure 12; wherein the first metal branch 15 includes a first extension portion 151 extending along the width direction X of the metal structure 12 and a second extension portion 152 extending in the direction of the metal structure 12, there is a strong electrical coupling between the first metal branch 15 and the second metal branch 16, and the expansion area of ​​the first metal branch 15 is greater than the expansion area of ​​the second metal branch 16, the second extension portion 152 is electrically connected to the metal structure 12, the signal line 141 of the first coaxial line is electrically connected to the second metal branch 16, and the ground line 142 of the first coaxial line is electrically connected to the metal structure 12;

[0040] like Figure 1 and Figure 3As shown, the second antenna structure includes a second coaxial line 17 and a third metal branch 18 and a fourth metal branch 19 located in the same plane and spaced apart; the third metal branch 18 and the fourth metal branch 19 are both asymmetric structures, and the expansion area of ​​the third metal branch 18 is smaller than the expansion area of ​​the fourth metal branch 19, the signal line 171 of the second coaxial line is electrically connected to the fourth metal branch 19, the ground line 172 of the second coaxial line is electrically connected to the third metal branch 18, and the projections of the third metal branch 18 and the fourth metal branch 19 in the direction of the metal structure 12 all fall on the metal structure 12 and are not electrically connected to the metal structure 12;

[0041] The routing of the first coaxial line 14 and the second coaxial line 17 is quasi-"Y"-shaped, and the two coaxial lines are wired in parallel with each other after merging at the Y node 20, wherein the length of the coaxial line is greater than one-fourth of the wavelength corresponding to the lowest operating frequency of the antenna structure in which it is located. Specifically, for the first coaxial line 14, the length of the first coaxial line 14 is greater than one-fourth of the wavelength corresponding to the lowest operating frequency of the antenna of the first antenna structure; for the second coaxial line 17, the length of the second coaxial line 17 is greater than one-fourth of the wavelength corresponding to the lowest operating frequency of the antenna of the second antenna structure.

[0042] It should be noted that the X direction and the Y direction are defined with reference to the overall direction of the two adjacent sides of the metal structure 12, for example Figure 1 In the embodiment, when the metal structure 12 is a regular rectangle, the X direction and the Y direction are two adjacent side length directions of the metal structure 12, such as Figure 1 and when the shape of the metal structure 12 is irregular, the X direction and the Y direction are the overall trend direction of the two adjacent sides of the metal structure 12.

[0043] In the present invention, on the one hand, the unfolded area of ​​the first metal branch node 15 is set to be larger than the unfolded area of ​​the second metal branch node 16 and is electrically connected to the metal structural member 12 and grounded together, so that the first antenna structure can achieve low-frequency resonance through strong coupling, and then combined with the second metal branch node 16 with a small unfolded area to achieve the resonance of the first antenna structure in the medium and high frequency bands, so that the first antenna structure covers a wide-band antenna; on the other hand, by setting the third metal branch node 18 and the fourth metal branch node 19 with an asymmetric structure, which is equivalent to an unbalanced dipole, and the third metal branch node 18 with a smaller unfolded area is electrically connected to the ground wire 172 of the second coaxial line, the electrical length of the third metal branch node 18 is effectively increased, so that the second antenna structure can achieve low-frequency resonance, and then combined with the second metal branch node 16 with a small unfolded area to achieve the resonance of the medium and high frequency bands of the first antenna structure, so that the first antenna structure covers a wide-band antenna. The fourth metal branch 19 and the third metal branch 18 together realize the resonance of the middle and high frequencies of the second antenna structure, so that the second antenna structure is covered as a wide-band antenna; furthermore, the third metal branch 18 and the fourth metal branch 19 are not directly electrically connected to the metal structure 12, that is, there is no direct electrical connection between the first antenna structure and the second antenna structure, so that in this antenna system, the "reference ground" of the first antenna structure and the second antenna structure are cleverly well isolated, thereby improving the isolation; finally, the first coaxial line 14 and the second coaxial line 17 are set as a "Y"-shaped routing, which further reduces the influence of the first coaxial line 14 on the current on the grounding line 172 of the second coaxial line, which not only ensures the simplicity of wiring, but also further improves the isolation between the two antenna structures. In this way, the box antenna system of the present invention solves the problem of integrating more than two wide-band antennas in a narrow space while satisfying the isolation, especially the isolation of the low-frequency band.

[0044] like Figure 1 As shown, as an example, the first metal branch 15 and the second metal branch 16 are both formed by bending rectangular metal, that is, the rectangular metal sheet is bent through a bending process to form the extension of the corresponding metal branch, and the metal branch in this way belongs to an integrally formed structure. However, it is not limited to this, the first metal branch 15 and the second metal branch 16 can also be an integrally formed structure formed by bending metal of other shapes, or a metal branch structure formed by fixing two parts together, which is not excessively limited in the present invention.

[0045] As an example, the length of the coaxial line from the Y node 20 to the feeding position is not less than one sixth of the wavelength of the medium corresponding to the lowest operating frequency of the antenna structure in which it is located. Specifically, for the first coaxial line 14, the length of the coaxial line from the Y node 20 to the feeding position of the signal line 141 of the first coaxial line is not less than one sixth of the wavelength of the medium corresponding to the lowest operating frequency of the antenna of the first antenna structure; for the second coaxial line 17, the length of the coaxial line from the Y node 20 to the feeding position of the signal line 171 of the second coaxial line is not less than one sixth of the wavelength of the medium corresponding to the lowest operating frequency of the antenna of the second antenna structure.

[0046] As an example, the second extension portion 152 may be electrically connected to the metal structure 12 by at least one of a series and / or parallel inductor, capacitor, and switch element. Figure 8 As shown, the second extension portion 152 is electrically connected to the metal structure 12 through a series inductor 24 to increase the effective electrical length of the first metal branch 15, so that the frequency covered by the first antenna structure is lower; the second extension portion 152 can also be connected in series with a capacitor to reduce the effective electrical length of the first metal branch 15; the second extension portion 152 can also be connected in series with a switch element after connecting a capacitor in parallel to an inductor to achieve any option of increasing or reducing the effective electrical length of the first metal branch 15.

[0047] like Figure 1 As shown, as an example, the second metal branch 16 includes a third extension portion 161 extending along the width direction of the metal structure 12 and a fourth extension portion 162 extending toward the metal structure 12 , and the signal line 141 of the first coaxial line is electrically connected to the fourth extension portion 162 .

[0048] As an example, the shape of the metal structure 12 is not excessively limited. For example, the metal structure 12 can be Figure 1 The complete sheet structure may also have holes or seams inside it, and its edges may also have holes or seams.

[0049] As an example, a patch antenna can be set between the first antenna structure and the second antenna structure. The patch antenna will not affect the isolation of the entire antenna system and can bring more functions. For example, adding a patch antenna can enable the entire antenna system to realize GNSS, SDARS and other functions.

[0050] As an example, taking the feeding position of the second coaxial line 17 as the starting point, the outer end of the second coaxial line 17 at a distance of at least one quarter of the wavelength corresponding to the lowest operating frequency of the antenna of the second antenna structure is sleeved with a magnetic ring 21 or a balun structure. At a frequency above 500M, the high impedance characteristics of the magnetic ring 21 due to its high inductance can effectively block the flow of current on the GND outside the coaxial line, thereby reducing the impact of radiation from electronic equipment and the like near the coaxial line routing on the antenna performance and improving the anti-noise ability of the antenna. Preferably, the material used for the magnetic ring 21 is that when the antenna frequency is 0.7GHz, the magnetic permeability of the material is 390~410 and the magnetic loss tangent is 0.4~0.6.

[0051] like Figure 1 As shown, as an example, the first coaxial line 14 and the second coaxial line 17 are arranged to maintain a certain distance before merging at the Y node 20 by providing an insulating clip 22. The material of the insulating clip 22 is generally selected from plastic material, but it is not limited thereto, as long as it is a material with good insulation performance. The size and number of the insulating clips 22 are designed according to actual needs and are not limited here.

[0052] As an example, a PCB board 13 is arranged above the metal structural part, and the PCB board 13 has an insulating area and a circuit area. The first metal branch 15 and the second metal branch 16 are arranged in the insulating area of ​​the PCB board 13, and the third metal branch 18 and the fourth metal branch 19 can be formed by processing the metal layer of the PCB board 13.

[0053] As an example, the antenna system includes two pairs of the first antenna structure and the second antenna structure arranged in pairs distributed along the length direction Y of the metal structure 12. Figure 8 As shown, two pairs of the first antenna structure and the second antenna structure are arranged in pairs, and the layout is first antenna structure-second antenna structure-second antenna structure-first antenna structure from left to right; of course, the layout can also be first antenna structure-second antenna structure-first antenna structure-second antenna structure from left to right. Figure 1 As shown, as an example, the box antenna system can be packaged by a box cover 11, the first antenna structure and the second antenna structure are placed on the upper layer of the box cover 11 as much as possible, and the metal structure 12 is placed on the lower layer of the box cover as much as possible to improve the antenna isolation.

[0054] The high isolation broadband antenna system of the present invention will be described in detail below in conjunction with specific drawings and corresponding embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0055] like Figures 1 to 5 As shown, this embodiment is a box antenna system with a size of 80mm×60mm×15mm, which functionally includes two broadband antennas applied to 5G cellular communications and can be placed in the dashboard of a car.

[0056] like Figure 1 As shown, the bottom of the box antenna system is a metal structure 12. The first antenna structure is set on one side of the 80mm long side, that is, on the 60mm wide side, wherein: the first metal branch 15 is directly electrically connected to the metal structure 12, and a 7nH inductor is connected in series with the second extension 152 of the first metal branch 15 near the part connected to the metal structure 12. Through the adjustment of the inductor, the first antenna structure can achieve resonance in the 600M frequency band. The first metal branch 15 is strongly coupled with the second metal branch 16 through a gap of about 20mm×3mm. The specific feeding structure is shown in FIG. Figure 2 As shown, the signal line 141 of the first coaxial line is electrically connected to the fourth extension portion 162 of the second metal branch 16 to feed the first antenna structure. The ground line 142 of the first coaxial line is directly electrically connected to the metal structure 12 .

[0057] The second antenna structure is arranged on the other side of the 80 mm long side. The third metal branch 18 and the fourth metal branch 19 of the second antenna structure are 13 mm away from the metal structure, and neither of them is directly electrically connected to the metal structure 12. The specific feeding structure is as follows: Figure 3 As shown, the signal line 171 of the second coaxial line is connected to the fourth metal branch 19 with a larger area, the ground line 172 of the second coaxial line is connected to the third metal branch 18 with a smaller area, and the ground line 172 of the second coaxial line has no direct electrical connection with the metal structure 12.

[0058] like Figure 1As shown, the wiring spacing between the first coaxial line 14 and the second coaxial line 17 after extending from the box cover 11 is 3 cm, which can be achieved by adding a plastic clip 22 between the two coaxial lines. They begin to converge at about 10 cm to form a Y node 20, and are wired in parallel after the Y node 20, forming a Y-shaped shape as a whole. The total length of each coaxial line is about 25 cm. The lowest frequency in the antenna frequency band designed in this embodiment is about 600 MHz, and the length of the coaxial line is greater than one quarter of its wavelength.

[0059] like Figure 4 and Figure 5 As shown in FIG. , it is the simulation performance result of this embodiment. Figure 4 To simulate the S parameter diagram, the design of this embodiment also achieves an isolation of more than -10dB in the low-frequency 600M-960M band; Figure 5 To simulate the efficiency diagram, in the low frequency band of 600M-1G, all efficiencies are above -6dB, and in the mid-frequency and high-frequency bands, the radiation efficiency is above -4dB. Example 2

[0060] The structure of this embodiment is basically the same as that of the embodiment 1, except that a magnetic ring 21 device is arranged outside the second coaxial line 17 in the second antenna structure. Specifically, the magnetic ring 21 device is arranged at a distance of about 15 cm (slightly larger than 12 cm, a quarter wavelength of the 600M frequency) from the feeding point. Figure 6 As shown. For the second antenna structure in Example 1, the outer layer of the ground wire 172 of the second coaxial line connected thereto will have current distributed thereon, especially in the low frequency band. If the wiring is not arranged properly, it will be affected by the radiation of the electronic equipment near the wiring inside the car, thereby introducing noise to the box antenna system. Therefore, the magnetic ring 21 device is provided. Due to the high inductance of the material of the magnetic ring 21 device, the high frequency band current on the outer side of the coaxial line behind the magnetic ring 21 (away from the antenna direction) is well suppressed.

[0061] like Figure 6 and Figure 7 As shown in the figure, the simulation current results when the magnetic ring is added and when the magnetic ring is not added are shown. From the figure, it can be seen that by adding the magnetic ring 21 device, the original efficiency performance is not affected (such as Figure 7 As shown), the current distribution range is effectively limited. Figure 6 When the magnetic ring 21 is not added in Figure a, the current will extend and distribute on the outer layer of the grounding wire 172 of the entire second coaxial line. Figure 6 In Figure b, when the magnetic ring 21 is added, the current will be cut off near the magnetic ring 21, thereby reducing the impact of radiation from electronic equipment near the coaxial line on the antenna performance and enhancing the antenna's anti-noise ability. Example 3

[0062] like Figures 8 to 11 As shown, this embodiment realizes the broadband design of four 5G cellular communication antennas in a box space of 160mm×60mm×15mm. It can be placed in the dashboard of a car as an upgrade of embodiment 1.

[0063] like Figure 8 As shown, the bottom side of the box system is a metal structure 12 with a size of 160cm×60cm, and four 5G cellular communication antennas are Figure 8 From left to right, the first antenna system-the second antenna system-the second antenna system-the first antenna system in Example 1 are arranged one after another, wherein the two first antenna systems are arranged on both sides of the long side of the PCB board 13, and the design structures of the two first antenna systems are the same. The antenna systems may refer to the description of the first antenna structure in Example 1, and the feeding structures may refer to the description of the first antenna structure in Example 1. Figure 2 , and a 7nH inductor 24 is connected in series at a location where the second extension portion 152 of the first metal branch 15 is close to the connection with the metal structure 12 .

[0064] The two second antenna structures are arranged between the two first antenna structures. The specific patterns of the third metal branches and the fourth metal branches in the two second antenna structures are not limited and can be the same or different. However, the antenna form and the feeding structure can be the same as those in Embodiment 1. For details, please refer to Figure 3 .

[0065] like Figure 8 As shown, the total length of the four coaxial lines (i.e., the first coaxial line-the second coaxial line-the second coaxial line-the first coaxial line) connected to the four antenna systems (i.e., the first antenna system-the second antenna system-the second antenna system-the first antenna system) is about 30 cm each, and the length of the same coaxial line is greater than a quarter of the wavelength of 600M. The four coaxial lines begin to converge at about 10 cm to form a Y node 20, and the normal wiring begins after the Y node 20. The overall distribution is quasi-Y-shaped.

[0066] By adjusting the order of setting the antenna structure, adjusting the distance between the antennas and arranging the coaxial line, the isolation requirements between the antennas can be well achieved.

[0067] like Figures 9 to 11 As shown in FIG. 1 , the performance results of this embodiment are shown in FIG. 1 . The measured S parameters are shown in FIG. Fig. 9 As shown in FIG10 , the design of this embodiment basically achieves an isolation of more than -10dB in the low-frequency band of 600M-960M. The radiation efficiency in the low-frequency band of 600M-700M is more than -7dB. After adding the matching circuit part, the antenna efficiency can be further improved.

[0068] In addition, a patch antenna may be added between two adjacent antenna systems, that is, between the first antenna system and the second antenna system, or between the second antenna system and the second antenna system, or between the second antenna system and the first antenna system, so as to realize GNSS, SDRAS and other functions.

[0069] In summary, the present invention provides a high-isolation broadband antenna system. On the one hand, by setting the expanded area of ​​the first metal branch node to be larger than the expanded area of ​​the second metal branch node and electrically connecting to the metal structure and grounding together, the first antenna structure can achieve low-frequency resonance through strong coupling, and then combine with the second metal branch node with a small expanded area to achieve the resonance of the medium and high frequency bands of the first antenna structure, so that the first antenna structure covers a wide-band antenna; on the other hand, by setting the third metal branch node and the fourth metal branch node with an asymmetric structure, which is equivalent to an unbalanced dipole, and the third metal branch node with a smaller expanded area is electrically connected to the ground wire of the second coaxial line, the electrical length of the third metal branch node is effectively increased, so that the second antenna structure can achieve low-frequency resonance. The third metal branch node and the fourth metal branch node are combined to realize the resonance of the middle and high frequencies of the second antenna structure, so that the second antenna structure is covered as a wide-band antenna; furthermore, the third metal branch node and the fourth metal branch node are not directly electrically connected to the metal structure, that is, there is no direct electrical connection between the first antenna structure and the second antenna structure, so that in this antenna system, the "reference ground" of the first antenna structure and the second antenna structure is cleverly well isolated, so that the isolation between the two antenna structures is improved; finally, the first coaxial line and the second coaxial line are set as a "Y"-shaped routing, which further reduces the influence of the first coaxial line on the current on the grounding line of the second coaxial line, which not only ensures the simplicity of wiring, but also further improves the isolation between the two antenna structures. In this way, the box antenna system of the present invention solves the problem of integrating more than two wide-band antennas in a narrow space under the premise of satisfying isolation, especially under the premise of satisfying low-frequency band isolation. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A high isolation broadband antenna system, characterized in that: The antenna system comprises: A metal structure located at the bottom layer of the box, and a first antenna structure and a second antenna structure located above the metal structure and arranged in pairs, wherein the first antenna structure and the second antenna structure are arranged at intervals along the length direction of the metal structure; The first antenna structure includes a first coaxial line and a first metal branch and a second metal branch arranged at intervals along the width direction of the metal structure; wherein the first metal branch includes a first extension portion extending along the width direction of the metal structure and a second extension portion extending in the direction of the metal structure, there is a strong electrical coupling between the first metal branch and the second metal branch, and the expansion area of ​​the first metal branch is greater than the expansion area of ​​the second metal branch, the second extension portion is electrically connected to the metal structure, the signal line of the first coaxial line is electrically connected to the second metal branch, the ground line of the first coaxial line is electrically connected to the metal structure, and the first metal branch and the second metal branch are located inside the box; The second antenna structure includes a second coaxial line and a third metal branch and a fourth metal branch located in the same plane and spaced apart; the third metal branch and the fourth metal branch are both asymmetric structures, and the expansion area of ​​the third metal branch is smaller than the expansion area of ​​the fourth metal branch, the signal line of the second coaxial line is electrically connected to the fourth metal branch, the ground line of the second coaxial line is electrically connected to the third metal branch, the projections of the third metal branch and the fourth metal branch in the direction of the metal structure all fall on the metal structure and are not electrically connected to the metal structure, and the third metal branch and the fourth metal branch are located inside the box; The routing of the first coaxial line and the second coaxial line is quasi-Y-shaped, and the two coaxial lines are wired in parallel with each other after merging at the Y node, wherein the length of the coaxial line is greater than one quarter of the wavelength corresponding to the lowest operating frequency of the antenna of the antenna structure in which it is located.

2. The high isolation broadband antenna system according to claim 1, characterized in that: The length of the coaxial line from the Y node to the feeding position shall not be less than one sixth of the wavelength of the medium corresponding to the lowest operating frequency of the antenna in the antenna structure in which it is located.

3. The high isolation broadband antenna system according to claim 1, characterized in that: The second extension portion is electrically connected to the metal structure through at least one of a series and / or parallel inductor, capacitor and switch element.

4. The high isolation broadband antenna system according to claim 1, characterized in that: The second metal branch includes a third extension portion extending along the width direction of the metal structure and a fourth extension portion extending toward the metal structure, and the signal line of the first coaxial line is electrically connected to the fourth extension portion.

5. The high isolation broadband antenna system according to claim 1, characterized in that: The metal structural member has slots and / or holes.

6. The high isolation broadband antenna system according to claim 1, characterized in that: A patch antenna is arranged between the first antenna structure and the second antenna structure.

7. The high isolation broadband antenna system according to claim 1, characterized in that: The antenna system includes two pairs of first antenna structures and second antenna structures that are arranged in pairs and distributed along the length direction of the metal structure.

8. The high isolation broadband antenna system according to claim 7, characterized in that: The two pairs of the first antenna structure and the second antenna structure are arranged in pairs in a layout manner of: first antenna structure-second antenna structure-second antenna structure-first antenna structure, or first antenna structure-second antenna structure-first antenna structure-second antenna structure.

9. The high isolation broadband antenna system according to claim 1, characterized in that: Starting from the feeding position of the second coaxial line, a magnetic ring or a balun structure is sleeved on the outer end of the second coaxial line at a distance of at least one quarter of the wavelength corresponding to the lowest operating frequency of the antenna of the second antenna structure.

10. The high isolation broadband antenna system according to claim 9, characterized in that: The material used for the magnetic ring has a magnetic permeability of 390-410 and a magnetic loss tangent of 0.4-0.6 at 0.7 GHz.

11. The high isolation broadband antenna system according to claim 1, characterized in that: Before the first coaxial line and the second coaxial line meet at the Y node, an insulating clamp is provided to achieve a wiring method in which a certain distance is maintained.

12. The high isolation broadband antenna system according to claim 1, characterized in that: A PCB board is arranged above the metal structural member, the first metal branch node and the second metal branch node are arranged in an insulating area of ​​the PCB board, and the third metal branch node and the fourth metal branch node are formed by processing the metal layer of the PCB board.

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