MIMO array antenna based on three-port antenna module and design method thereof

Abstract

The invention discloses an MIMO array antenna based on three-port antenna modules and a design method thereof, and relates to the technical field of microstrip antennae, and the array antenna comprises a main dielectric substrate, a metal ground and a plurality of three-port antenna modules. The metal ground is arranged below the main dielectric substrate with the air layer therebetween, and the three-port antenna module is arranged on the upper surface of the main dielectric substrate and comprises L-shaped and square microstrip patch antennas and a plurality of groups of metal short circuit columns. The square microstrip patch antenna is arranged along the right-angle side of the inner side of the L-shaped microstrip patch antenna, the right-angle sides of the square microstrip patch antenna and the L-shaped microstrip patch antenna are parallel, and the three-port antenna module is symmetrical about the diagonal line of the L-shaped microstrip patch antenna and is provided with three feed ports. Through the first metal short-circuit column group, the second metal short-circuit column group, the third metal short-circuit column group and the gaps in the L-shaped microstrip patch antenna, the frequency band of the L-shaped microstrip patch antenna can be reduced, the bandwidth of the square microstrip patch antenna can be expanded, the isolation degree of each feed port can be improved, and the N79 frequency band can be completely covered. The antenna is compact in structure and low in profile, realizes zero clearance, is adaptive to ultrathin and full-screen mobile terminals, and is suitable for the field of 5G and 6G mobile communication.

Description

Technical Field

[0001] This application relates to the field of microstrip antenna technology, and in particular to a MIMO array antenna based on a three-port antenna module and its design method. Background Technology

[0002] With the rapid development and commercial deployment of 5G mobile communication technology, the requirements for data transmission rates, system capacity, connection density, and user experience in mobile communication networks have reached unprecedented levels. 5G systems not only need to support the sub-6GHz core frequency bands (such as 3.4-3.6GHz and 4.4-5.0GHz), but also need to cover some low-frequency bands to enhance signal coverage. To meet these requirements, Multiple Input Multiple Output (MIMO) technology has become one of the core technologies of 5G. This technology, by deploying multiple antenna elements at the transceiver end, fully utilizes spatial degrees of freedom, significantly improving channel capacity and spectral efficiency, and is a key support for achieving high-speed, high-reliability communication.

[0003] Implementing high-performance MIMO antenna systems in mobile terminals faces a series of severe and intertwined challenges. The primary limitation stems from the continuous evolution of mobile terminal devices towards thinner and lighter designs and full-screen displays, resulting in extremely compressed physical space available for antennas. Simultaneously, 5G applications require antennas to cover a wider frequency band, placing higher demands on operating bandwidth. Densely arranging multiple antenna elements within such a compact space inevitably leads to strong mutual coupling effects, severely impairing MIMO system performance—such as reducing channel capacity and increasing bit error rate—thus necessitating a design with high isolation between ports. Furthermore, the ultra-thin design of terminal devices strictly limits the antenna profile height, making it difficult to accommodate complex three-dimensional structures or large-sized antennas. Given these backgrounds and existing technological bottlenecks, the industry urgently needs a novel MIMO antenna design suitable for modern ultra-thin 5G mobile terminals. Summary of the Invention

[0004] The purpose of this application is to provide a MIMO array antenna based on a three-port antenna module and its design method, so as to solve the problems of large antenna size, narrow frequency band, low isolation and dependence on clearance area in the prior art.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] In a first aspect, this application provides a MIMO array antenna based on a three-port antenna module, comprising: a main dielectric substrate, a metal ground, and a plurality of three-port antenna modules; the metal ground is separated by an air layer disposed below the main dielectric substrate, and the plurality of three-port antenna modules are disposed on the upper surface of the main dielectric substrate; the three-port antenna module includes an L-shaped microstrip patch antenna, a square microstrip patch antenna, and a plurality of metal short-circuit posts; the square microstrip patch antenna is arranged along the inner right-angled side of the L-shaped microstrip patch antenna, and the right-angled sides of the two are parallel to each other; the first feed port and the second feed port are located on both sides of the diagonal of the L-shaped microstrip patch antenna, and the third feed port is disposed on the diagonal of the square microstrip patch antenna, and the three-port antenna module is symmetrical about the diagonal of the L-shaped microstrip patch antenna; the diagonal of the L-shaped microstrip patch antenna is the line connecting the inner right-angled vertex and the outer right-angled vertex; each feed port is fed using a coaxial feeding method.

[0007] A first group of metal short-circuit pillars is provided on both sides of the diagonal of the L-shaped microstrip patch antenna to reduce the frequency band of the L-shaped microstrip patch antenna and improve the isolation between the first and second feed ports. A second group of metal short-circuit pillars is provided on both sides of the right-angled side of the square microstrip patch antenna away from the L-shaped microstrip patch antenna to add a resonant frequency point to the square microstrip patch antenna and widen the operating bandwidth of the square microstrip patch. A third group of metal short-circuit pillars is provided between the L-shaped microstrip patch antenna and the square microstrip patch antenna to improve the isolation between the various feed ports. Two slots of the same size and parallel to each other are opened on the two inner right-angled sides of the L-shaped microstrip patch antenna to further reduce the frequency band of the L-shaped microstrip patch antenna and fully cover the N79 frequency band.

[0008] Optionally, the first group of metal short-circuit pillars includes several metal short-circuit pillars; several metal short-circuit pillars on either side of the diagonal of the L-shaped microstrip patch antenna form a straight line parallel to the diagonal of the L-shaped microstrip patch antenna; the spacing between several metal short-circuit pillars on either side of the diagonal of the L-shaped microstrip patch antenna is the same; and two of the metal short-circuit pillars are located on the inner right-angled side of the L-shaped microstrip patch antenna.

[0009] Optionally, the second group of metal short-circuit pillars includes several metal short-circuit pillars; the straight line formed by several metal short-circuit pillars on either side of the right angle away from the square microstrip patch antenna is parallel to the corresponding right angle side on the same side; the spacing between several metal short-circuit pillars on the same side is the same.

[0010] Optionally, none of the metal short-circuit posts in the third group of metal short-circuit posts are in contact with the square microstrip patch antenna or the L-shaped microstrip patch antenna.

[0011] Optionally, several metal short-circuit pillars in the first metal short-circuit pillar group penetrate the L-shaped microstrip patch antenna, the main dielectric substrate, and the air layer from top to bottom, and contact the metal ground; several metal short-circuit pillars in the second and third metal short-circuit pillar groups penetrate the main dielectric substrate and the air layer from top to bottom, and contact the metal ground.

[0012] Optionally, when the number of three-port antenna modules is 4, the four three-port antenna modules are respectively located at the four corners of the main dielectric substrate; the two end edges of the L-shaped microstrip patch antenna of any three-port antenna module coincide with the edge of the main dielectric substrate.

[0013] Optionally, when the number of three-port antenna modules is 6, the layout of 4 of the three-port antenna modules is the same as the layout when the number of three-port antenna modules is 4, and the remaining 2 three-port antenna modules are respectively set in the middle of the two long sides of the main dielectric substrate. The 2 three-port antenna modules set in the middle of the two long sides of the main dielectric substrate do not have sides that coincide with the sides of the main dielectric substrate.

[0014] Secondly, this application provides a design method for a MIMO array antenna based on a three-port antenna module, including the following steps:

[0015] Each three-port antenna module on the upper surface of the main dielectric substrate is fed using a coaxial feeding method. A metal ground is provided below the main dielectric substrate with an air gap. The three-port antenna module includes an L-shaped microstrip patch antenna and a square microstrip patch antenna. The square microstrip patch antenna is arranged along the inner right-angled side of the L-shaped microstrip patch antenna, and the right-angled sides of the two are parallel to each other. The first and second feed ports are located on both sides of the diagonal of the L-shaped microstrip patch antenna, and the third feed port is located on the diagonal of the square microstrip patch antenna. The three-port antenna module is symmetrical about the diagonal of the L-shaped microstrip patch antenna. The diagonal of the L-shaped microstrip patch antenna is the line connecting the inner right-angled vertex and the outer right-angled vertex.

[0016] A first metal short-circuit post group is set on both sides of the diagonal of the L-shaped microstrip patch antenna; the first metal short-circuit post group is used to reduce the frequency band of the L-shaped microstrip patch antenna and improve the isolation between the first feed port and the second feed port.

[0017] Two parallel slits of the same size are made on the two inner right-angled sides of the L-shaped microstrip patch antenna; the slits are used to further reduce the frequency band of the L-shaped microstrip patch antenna and fully cover the N79 frequency band.

[0018] A second metal short-circuit post group is set on both sides of the right angle of the square microstrip patch antenna away from the L-shaped microstrip patch antenna; the second metal short-circuit post group is used to add a resonant frequency point to the square microstrip patch antenna and widen the operating bandwidth of the square microstrip patch.

[0019] A third metal short-circuit post group is set between the gap between the L-shaped microstrip patch antenna and the square microstrip patch antenna; the third metal short-circuit post group is used to improve the isolation between each feed port.

[0020] Optionally, several metal short-circuit pillars in the first metal short-circuit pillar group penetrate the L-shaped microstrip patch antenna, the main dielectric substrate, and the air layer from top to bottom, and contact the metal ground; several metal short-circuit pillars in the second and third metal short-circuit pillar groups penetrate the main dielectric substrate and the air layer from top to bottom, and contact the metal ground.

[0021] Optionally, when the number of three-port antenna modules is 4, the four three-port antenna modules are respectively located at the four corners of the main dielectric substrate; the two end edges of the L-shaped microstrip patch antenna of any three-port antenna module coincide with the edge of the main dielectric substrate.

[0022] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0023] This application provides a MIMO array antenna based on a three-port antenna module and its design method. The array antenna includes: a main dielectric substrate, a metal ground, and several three-port antenna modules. The metal ground is separated by an air layer below the main dielectric substrate. This structural design enables the antenna to form a low-profile structure, which can adapt to the design requirements of ultra-thin mobile terminal devices. Several three-port antenna modules are disposed on the upper surface of the main dielectric substrate. The three-port antenna module includes an L-shaped microstrip patch antenna, a square microstrip patch antenna, and several sets of metal shorting posts. The square microstrip patch antenna is arranged along the inner right-angle side of the L-shaped microstrip patch antenna. This compact arrangement effectively reduces the space occupied by the antenna module and greatly improves the utilization rate of the internal space of the mobile terminal.

[0024] To address the issues of narrow antenna bands, low isolation, and reliance on clearance in existing technologies, a first group of metal short-circuit pillars is provided on both sides of the diagonal of the L-shaped microstrip patch antenna. This makes the frequency band of the L-shaped microstrip patch antenna more suitable for 5G communication requirements, and the isolation between the two feed ports can be increased to over 10dB, effectively reducing the mutual coupling effect between ports. A second group of metal short-circuit pillars is provided on both sides of the right-angled side of the square microstrip patch antenna away from the L-shaped microstrip patch antenna. This expands the square microstrip patch antenna from a single resonant frequency point to a dual resonant frequency point, extending the operating bandwidth to lower frequencies. To meet the requirements of broadband communication, a third metal short-circuit post group is provided between the L-shaped microstrip patch antenna and the square microstrip patch antenna, which can improve the isolation between the first and second feed ports and the third feed port to more than 10dB, further optimizing the performance of the MIMO system. Two identical and parallel slots are opened on the two inner right-angled sides of the L-shaped microstrip patch antenna, which further reduces the frequency band of the L-shaped microstrip patch antenna and ensures that it can fully cover the N79 band (4.4-5.0GHz), meeting the frequency band requirements of 5G communication. At the same time, the metal ground in the entire antenna structure does not need to be slotted, realizing a zero clearance design, which can be perfectly adapted to full-screen mobile terminals and avoid the dependence on clearance area of ​​traditional antennas. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This application provides a schematic diagram of the structure of a MIMO array antenna based on a three-port antenna module, according to one embodiment of the present application.

[0027] Figure 2 This application provides a schematic diagram of the structure of a three-port antenna module in a MIMO array antenna based on a three-port antenna module, according to one embodiment of the present application.

[0028] Figure 3 This application provides a schematic diagram of the structure of a MIMO array antenna with six three-port antenna modules, according to another embodiment of the present application.

[0029] Figure 4 This is a flowchart illustrating a design method for a MIMO array antenna based on a three-port antenna module, provided in one embodiment of this application.

[0030] Figure 5 The graph shows the reflection coefficient of a MIMO array antenna based on a three-port antenna module as a function of frequency, according to an embodiment of this application.

[0031] Figure 6 This is a schematic diagram showing the transmission coefficient of a MIMO array antenna based on a three-port antenna module as a function of frequency, provided as an embodiment of this application.

[0032] Figure 7 This is a schematic diagram showing the envelope correlation coefficient of a MIMO array antenna based on a three-port antenna module as a function of frequency, according to an embodiment of this application.

[0033] Figure 8 This is a schematic diagram showing the efficiency of a MIMO array antenna based on a three-port antenna module as a function of frequency, provided as an embodiment of this application.

[0034] Figure label:

[0035] 1: Main dielectric substrate; 2: Metal ground; 3: Air layer; 4: Three-port antenna module; 5: L-shaped microstrip patch antenna; 6: Square microstrip patch antenna; 7: Slot; 8: First metal short-circuit post group; 9: Second metal short-circuit post group; 10: Third metal short-circuit post group; 11: First feed port; 12: Second feed port; 13: Third feed port. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] This application provides an embodiment of a MIMO array antenna based on a three-port antenna module, such as... Figure 1 As shown, it includes: a main dielectric substrate 1, a metal ground 2, and several three-port antenna modules 4; the metal ground 2 is separated by an air layer 3 below the main dielectric substrate 1, and the several three-port antenna modules 4 are disposed on the upper surface of the main dielectric substrate 1.

[0039] like Figure 2As shown, the three-port antenna module 4 includes an L-shaped microstrip patch antenna 5, a square microstrip patch antenna 6, and several sets of metal short-circuit posts. The square microstrip patch antenna 6 is arranged along the inner right-angled side of the L-shaped microstrip patch antenna 5, and the right-angled sides of the two are parallel to each other; the first feed port 11 and the second feed port 12 are located on both sides of the diagonal of the L-shaped microstrip patch antenna 5, and the third feed port 13 is located on the diagonal of the square microstrip patch antenna 6. The three-port antenna module 4 is symmetrical about the diagonal of the L-shaped microstrip patch antenna 5; the diagonal of the L-shaped microstrip patch antenna 5 is the line connecting the inner right-angled vertex and the outer right-angled vertex; each feed port is fed using a coaxial feeding method.

[0040] A first metal short-circuit post group 8 is provided on both sides of the diagonal of the L-shaped microstrip patch antenna 5 to reduce the frequency band of the L-shaped microstrip patch antenna 5 and improve the isolation between the first feed port 11 and the second feed port 12. Two slots 7 of the same size and parallel to each other are respectively opened on the two inner right-angled sides of the L-shaped microstrip patch antenna 5 to further reduce the frequency band of the L-shaped microstrip patch antenna 5 and completely cover the N79 frequency band.

[0041] Specifically, in this embodiment, the first metal short-circuit post group 8 includes a plurality of metal short-circuit posts; the plurality of metal short-circuit posts on either side of the diagonal of the L-shaped microstrip patch antenna 5 form a straight line parallel to the diagonal of the L-shaped microstrip patch antenna 5; the spacing between the plurality of metal short-circuit posts on either side of the diagonal of the L-shaped microstrip patch antenna 5 is the same; wherein two metal short-circuit posts are disposed on the inner right-angled side of the L-shaped microstrip patch antenna 5.

[0042] A second metal short-circuit post group 9 is provided on both sides of the right angle of the square microstrip patch antenna 6 away from the L-shaped microstrip patch antenna 5. This group is used to add a resonant frequency point to the square microstrip patch antenna 6 and widen the operating bandwidth of the square microstrip patch.

[0043] Specifically, the second metal short-circuit post group 9 includes several metal short-circuit posts; the straight line formed by several metal short-circuit posts on either side of the right angle away from the square microstrip patch antenna 6 and the corresponding right angle side on the same side is parallel; the spacing between several metal short-circuit posts on the same side is the same.

[0044] A third group of metal short-circuit posts 10 is provided between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 to improve the isolation between the various feed ports. In this embodiment, none of the metal short-circuit posts of the third group of metal short-circuit posts 10 are in contact with the square microstrip patch antenna 6 or the L-shaped microstrip patch antenna 5.

[0045] The number of metal short-circuit posts on both sides of the diagonal of the L-shaped microstrip patch antenna 5 and the distance between the metal short-circuit posts, as well as the number of metal short-circuit posts around the square microstrip patch antenna 6 and the distance between the metal short-circuit posts, can be changed accordingly. This allows for flexible adjustment of the isolation of the three-port antenna module 4 within a certain range as needed, without affecting the antenna's operating bandwidth.

[0046] In the above three groups of metal short-circuit pillars, several metal short-circuit pillars in the first group of metal short-circuit pillars 8 penetrate from top to bottom through the L-shaped microstrip patch antenna 5, the main dielectric substrate 1, and the air layer 3, and contact the metal ground 2; several metal short-circuit pillars in the second group of metal short-circuit pillars 9 and the third group of metal short-circuit pillars 10 penetrate from top to bottom through the main dielectric substrate 1 and the air layer 3, and contact the metal ground 2.

[0047] In an exemplary embodiment, when the number of three-port antenna modules 4 is 4, the four three-port antenna modules 4 are respectively disposed at the four corners of the main dielectric substrate 1; the two end edges of the L-shaped microstrip patch antenna 5 of any three-port antenna module 4 coincide with the edge of the main dielectric substrate 1.

[0048] In another exemplary embodiment, such as Figure 3 As shown, when the number of three-port antenna modules 4 is 6, the layout of 4 of the three-port antenna modules 4 remains the same as when the number of three-port antenna modules 4 is 4. The remaining 2 three-port antenna modules 4 are respectively located in the middle of the two long sides of the main dielectric substrate 1. The 2 three-port antenna modules 4 located in the middle of the two long sides of the main dielectric substrate 1 do not have sides that coincide with the sides of the main dielectric substrate 1. Therefore, Figure 3 In the current arrangement, the operating bandwidth of the two three-port antenna modules 4 in the central region of the main dielectric substrate 1 is narrower compared to the other three-port antenna modules 4. Of course, the number of three-port antenna modules 4 can be increased to form a larger-scale MIMO array antenna, as long as the layout of the three-port antenna modules 4 at the four corners of the main dielectric substrate 1 remains unchanged. Any excess three-port antenna modules 4 can be disposed of as follows: Figure 3 As shown, it is added in the middle region of the main dielectric substrate 1.

[0049] As an alternative implementation method, such as Figure 1 The diagram illustrates a 12×12 MIMO array antenna with 12 input ports and 12 output ports. The main dielectric substrate 1 measures 150mm × 80mm × 1.6mm, has a relative permittivity of 4, and a loss tangent of 0.0025. The metal ground plane 2 measures 150mm × 80mm, and the air layer 3 measures 150mm × 80mm × 0.4mm. The designed MIMO array antenna has a cross-sectional height of only 2mm. The main dielectric substrate 1 is made of TXP material; the metal ground plane 2 and the three-port antenna module 4 are made of metal.

[0050] The two outer right-angled sides of the L-shaped microstrip patch antenna 5 are 36 mm long, and the two inner right-angled sides are 18 mm long. The four slots 7 at the L-shaped microstrip patch antenna 5 are all 6.2 mm long. The side length of the square microstrip patch antenna 6 is 15.4 mm. The distance between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 is only 1.5 mm. The distance between each metal short-circuit post in the first metal short-circuit post group 8 arranged on the L-shaped microstrip patch antenna 5 is 2.7 mm, the distance between the two straight lines formed by the two groups of metal short-circuit posts is 1.41 mm, and the radius of each metal short-circuit post is 0.4 mm.

[0051] The distance between each metal short-circuit post in the second metal short-circuit post group 9 arranged near the two right-angled sides of the square microstrip patch antenna 6 is 1.5 mm. The distance between the straight line formed by each group of metal short-circuit posts and the side of the square microstrip patch antenna 6 is 0.5 mm. The radius of each metal short-circuit post is 0.3 mm.

[0052] The distance between the two metal shorting posts (the third metal shorting post group 10) arranged in the gap between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 and the L-shaped microstrip patch antenna 5 is 0.7 mm, and the distance between them and the square microstrip patch antenna 6 is 0.8 mm. The radius of each metal shorting post is 0.2 mm.

[0053] certainly, Figures 1-3 The array antenna architecture shown is merely exemplary; it can be omitted as needed to implement different functions. Figures 1-3 One or at least two components of the array antenna shown.

[0054] Based on the same inventive concept, embodiments of this application also provide a design method for designing the aforementioned MIMO array antenna based on a three-port antenna module. In an exemplary embodiment, such as Figure 4 As shown, the design method of this MIMO array antenna based on a three-port antenna module includes the following steps:

[0055] S1. The three-port antenna modules 4 on the upper surface of the main dielectric substrate 1 are fed using a coaxial feeding method. A metal ground 2 is provided below the main dielectric substrate 1 with an air gap 3. The three-port antenna module 4 includes an L-shaped microstrip patch antenna 5 and a square microstrip patch antenna 6. The square microstrip patch antenna 6 is arranged along the inner right-angle side of the L-shaped microstrip patch antenna 5, and the right-angle sides of the two are parallel to each other. The first feed port 11 and the second feed port 12 are located on both sides of the diagonal of the L-shaped microstrip patch antenna 5, and the third feed port 13 is set on the diagonal of the square microstrip patch antenna 6. The three-port antenna module 4 is symmetrical about the diagonal of the L-shaped microstrip patch antenna 5. The diagonal of the L-shaped microstrip patch antenna 5 is the line connecting the inner right-angle vertex and the outer right-angle vertex.

[0056] S2. A first metal short-circuit post group 8 is provided on both sides of the diagonal of the L-shaped microstrip patch antenna 5; the first metal short-circuit post group 8 is used to reduce the frequency band of the L-shaped microstrip patch antenna 5 and improve the isolation between the first feed port 11 and the second feed port 12.

[0057] S3. Two slots 7 of the same size and parallel to each other are opened on the two inner right-angled sides of the L-shaped microstrip patch antenna 5. The slots 7 are used to further reduce the frequency band of the L-shaped microstrip patch antenna 5 and fully cover the N79 frequency band.

[0058] The L-shaped microstrip patch antenna 5 is actually a zero-gap antenna pair module. The first feed port 11 and the second feed port 12 are both located on the L-shaped microstrip patch antenna 5 and share it for radiation. Without the first metal short-circuit post group 8, the frequency band of the L-shaped microstrip patch antenna 5 is relatively high, failing to completely cover the N79 band, and the isolation between the two feed ports is less than 10dB. After arranging two sets of metal short-circuit posts 8 parallel to the diagonal of the L-shaped microstrip patch antenna 5, the frequency band of the L-shaped microstrip patch antenna 5 decreases, and the isolation between the two feed ports is higher than 10dB, but the frequency band is still slightly high and cannot completely cover the N79 band. After creating slots in the L-shaped microstrip patch antenna 5, the frequency band of the L-shaped microstrip patch antenna 5 decreases, completely covering the N79 band, and the isolation between the two feed ports remains higher than 10dB.

[0059] S4. A second metal short-circuit post group 9 is set on both sides of the right angle of the square microstrip patch antenna 6 away from the L-shaped microstrip patch antenna 5; the second metal short-circuit post group 9 is used to add a resonant frequency point to the square microstrip patch antenna 6 and widen the operating bandwidth of the square microstrip patch 6.

[0060] S5. A third metal short-circuit post group 10 is set between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6; the third metal short-circuit post group 10 is used to improve the isolation between each feed port.

[0061] Without other structural elements, the square microstrip patch antenna 6 has only one resonant frequency, resulting in a narrow operating bandwidth. Adding a second group of metal short-circuit posts 9 along the two right-angled sides of the square microstrip patch antenna 6 adds another resonant frequency, extending the operating bandwidth to lower frequencies and giving it a wider bandwidth to cover the N79 band. However, the isolation between the various feed ports is now less than 10dB, requiring decoupling. Adding a third group of metal short-circuit posts 10 to the gap between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 improves the isolation between the feed ports to over 10dB.

[0062] During the design process, in order to meet the requirements of full-screen mobile phones, the proposed MIMO array antenna has no gaps on the metal ground and has the characteristic of zero clearance. In order to reduce the size of the three-port antenna module 4 in the mobile phone, the two feed ports share the L-shaped microstrip patch antenna 5 for radiation, and the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 are arranged compactly, which effectively improves the space utilization of antenna deployment inside the mobile terminal device.

[0063] In summary, the three-port antenna module 4 in this embodiment uses coaxial feeding for direct feeding; the L-shaped microstrip patch antenna 5, after adding two sets of metal short-circuit posts 8 and slotting, can reduce the operating frequency band and fully cover the N79 frequency band allocated in fifth-generation mobile communication. Furthermore, the first metal short-circuit post group 8 has a decoupling effect, which can effectively improve the isolation between the first feed port 11 and the second feed port 12 in the L-shaped microstrip patch antenna 5; after adding the second metal short-circuit post group 9 along the two right-angled sides of the square microstrip patch antenna 6, its bandwidth is effectively expanded; the third metal short-circuit post group 10 can improve the isolation between each feed port; the array antenna of this embodiment has the characteristics of compact structure, low profile, wide operating bandwidth, and zero clearance, which can well meet the current design requirements of mobile terminals.

[0064] To demonstrate the performance of the MIMO array antenna designed in this embodiment, curves showing the changes in reflection coefficient, transmission coefficient, envelope correlation coefficient, and efficiency with frequency are provided. Figures 5 to 8 As shown.

[0065] In a three-port antenna module 4, the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6 have different operating bandwidths. The bandwidth of the square microstrip patch antenna 6 is narrower than that of the L-shaped microstrip patch antenna 5, and the operating bandwidth of the square microstrip patch antenna 6 is within the operating bandwidth range of the L-shaped microstrip patch antenna 5. Figure 5 , Figure 6 From the S-parameters, it can be concluded that in the proposed 12×12 MIMO array antenna, the -6dB operating bandwidth of the L-shaped microstrip patch antenna 5 is 4.38GHz–5.48GHz, and the isolation between the first feed port 11 and the second feed port 12 in the L-shaped microstrip patch antenna 5 is higher than 10dB; the -6dB operating bandwidth of the square microstrip patch antenna 6 is 4.49GHz–5.38GHz, and the isolation between each feed port is higher than 10.4dB. Therefore, the three-port antenna module 4 proposed in this embodiment can cover the N79 frequency band allocated in fifth-generation mobile communication, and can simultaneously achieve wide bandwidth and miniaturization.

[0066] according to Figure 7 It can be seen that the envelope correlation coefficient between the first feed port 11 and the second feed port 12 of the MIMO array antenna proposed in this embodiment is less than 0.1 in the 4.38GHz-5.48GHz frequency band; and the envelope correlation coefficient between each feed port is less than 0.17 in the 4.49GHz-5.38GHz frequency band, which meets the requirement of less than 0.5 for mobile terminal devices.

[0067] according to Figure 8 As can be seen, within the 4.38GHz–5.48GHz frequency band, the efficiency of the L-shaped microstrip patch antenna 5 is higher than 66%; within the 4.49GHz–5.38GHz frequency band, the efficiency of the square microstrip patch antenna 6 is higher than 51%, meeting the requirement that the efficiency of mobile terminal antennas is greater than 40%, and the antennas have good radiation performance.

[0068] Compared with existing technologies, the array antenna of this application has the following significant advantages:

[0069] First, the L-shaped microstrip patch antenna 5 in the three-port antenna module 4 serves as a shared radiating patch. It and the square microstrip patch antenna 6 are arranged in a compact layout with a very small gap between the two patches, which significantly improves the space utilization of the antenna inside the mobile terminal.

[0070] Second, by adding two sets of metal short-circuit posts 8 parallel to the diagonal of the L-shaped microstrip patch antenna 5, the coupling between the first feed port 11 and the second feed port 12 in the three-port antenna module 4 is significantly reduced.

[0071] Third, metal shorting posts 9 are added along the two right-angled sides of the square microstrip patch antenna 6, which effectively expands the bandwidth of the patch.

[0072] Fourth, a metal shorting post 10 is added at the gap between the L-shaped microstrip patch antenna 5 and the square microstrip patch antenna 6, which significantly improves the isolation between the feed ports in the three-port antenna module 4.

[0073] Fifth, the array antenna of this application has dual operating frequency bands of 4.38GHz-5.48GHz and 4.49GHz-5.38GHz, which can efficiently cover the N79 frequency band allocated by 5G. Its bandwidth, isolation, efficiency and low profile all meet the communication requirements of MIMO antennas.

[0074] Sixth, the array antenna of this application has the characteristics of compact structure, low profile, wide operating bandwidth and zero clearance. While ensuring the ultra-thin full-screen design of mobile terminals, it can efficiently cover the 5G N79 frequency band and meet the diverse performance requirements of MIMO antenna systems such as high isolation and low envelope correlation coefficient. It is suitable for MIMO communication applications of mobile terminals such as 5G and 6G smartphones.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A MIMO array antenna based on a three-port antenna module, characterized in that, include: The main dielectric substrate, the metal ground, and several three-port antenna modules; The metal ground plane is disposed below the main dielectric substrate, and several three-port antenna modules are disposed on the upper surface of the main dielectric substrate. Each three-port antenna module includes an L-shaped microstrip patch antenna, a square microstrip patch antenna, and several sets of metal short-circuit posts. The square microstrip patch antenna is arranged along the inner right-angled side of the L-shaped microstrip patch antenna, and the right-angled sides of the two antennas are parallel to each other. The first and second feed ports are located on either side of the diagonal of the L-shaped microstrip patch antenna, and the third feed port is located on the diagonal of the square microstrip patch antenna. The three-port antenna modules are symmetrical about the diagonal of the L-shaped microstrip patch antenna. The diagonal of the L-shaped microstrip patch antenna is the line connecting the inner right-angled vertex and the outer right-angled vertex. Each feed port is fed using a coaxial feeding method. A first group of metal short-circuit posts is provided on both sides of the diagonal of the L-shaped microstrip patch antenna to reduce the frequency band of the L-shaped microstrip patch antenna and improve the isolation between the first feed port and the second feed port. A second group of metal short-circuit posts is provided on both sides of the right-angled side of the square microstrip patch antenna away from the L-shaped microstrip patch antenna to add a resonant frequency point to the square microstrip patch antenna and widen the operating bandwidth of the square microstrip patch. A third group of metal short-circuit posts is provided between the L-shaped microstrip patch antenna and the square microstrip patch antenna to improve the isolation between the feed ports. Two slots of the same size and parallel to each other are opened on the two inner right-angled sides of the L-shaped microstrip patch antenna to further reduce the frequency band of the L-shaped microstrip patch antenna and completely cover the N79 frequency band.

2. The MIMO array antenna based on a three-port antenna module according to claim 1, characterized in that, The first metal short-circuit post group includes a plurality of metal short-circuit posts; the plurality of metal short-circuit posts on either side of the diagonal of the L-shaped microstrip patch antenna form a straight line parallel to the diagonal of the L-shaped microstrip patch antenna; the spacing between the plurality of metal short-circuit posts on either side of the diagonal of the L-shaped microstrip patch antenna is the same; wherein two metal short-circuit posts are disposed on the inner right-angled side of the L-shaped microstrip patch antenna.

3. The MIMO array antenna based on a three-port antenna module according to claim 1, characterized in that, The second metal short-circuit post group includes several metal short-circuit posts; the straight line formed by several metal short-circuit posts on either side of the right angle away from the square microstrip patch antenna and the corresponding right angle side on the same side is parallel; the spacing between several metal short-circuit posts on the same side is the same.

4. The MIMO array antenna based on a three-port antenna module according to claim 1, characterized in that, None of the metal short-circuit posts in the third group of metal short-circuit posts are in contact with the square microstrip patch antenna or the L-shaped microstrip patch antenna.

5. The MIMO array antenna based on a three-port antenna module according to claim 1, characterized in that, Several metal short-circuit pillars in the first metal short-circuit pillar group penetrate the L-shaped microstrip patch antenna, the main dielectric substrate, and the air layer from top to bottom, and contact the metal ground; several metal short-circuit pillars in the second and third metal short-circuit pillar groups penetrate the main dielectric substrate and the air layer from top to bottom, and contact the metal ground.

6. The MIMO array antenna based on a three-port antenna module according to claim 1, characterized in that, When the number of the three-port antenna modules is 4, the four three-port antenna modules are respectively located at the four corners of the main dielectric substrate; the two end edges of the L-shaped microstrip patch antenna of any three-port antenna module coincide with the edge of the main dielectric substrate.

7. The MIMO array antenna based on a three-port antenna module according to claim 6, characterized in that, When the number of three-port antenna modules is 6, the layout of 4 of the three-port antenna modules is the same as the layout when the number of three-port antenna modules is 4. The remaining 2 three-port antenna modules are respectively located in the middle of the two long sides of the main dielectric substrate. The 2 three-port antenna modules located in the middle of the two long sides of the main dielectric substrate do not have sides that coincide with the sides of the main dielectric substrate.

8. A design method for a MIMO array antenna based on a three-port antenna module, characterized in that, include: Each three-port antenna module on the upper surface of the main dielectric substrate is fed using a coaxial feeding method. A metal ground plane is provided below the air gap of the main dielectric substrate; the three-port antenna module includes an L-shaped microstrip patch antenna and a square microstrip patch antenna; the square microstrip patch antenna is arranged along the inner right-angled side of the L-shaped microstrip patch antenna, and the right-angled sides of the two are parallel to each other; the first feed port and the second feed port are located on both sides of the diagonal of the L-shaped microstrip patch antenna, and the third feed port is located on the diagonal of the square microstrip patch antenna; the three-port antenna module is symmetrical about the diagonal of the L-shaped microstrip patch antenna; the diagonal of the L-shaped microstrip patch antenna is the line connecting the inner right-angled vertex and the outer right-angled vertex; A first metal short-circuit post group is provided on both sides of the diagonal of the L-shaped microstrip patch antenna; the first metal short-circuit post group is used to reduce the frequency band of the L-shaped microstrip patch antenna and improve the isolation between the first feed port and the second feed port; Two parallel slits of the same size are made on the two inner right-angled sides of the L-shaped microstrip patch antenna; the slits are used to further reduce the frequency band of the L-shaped microstrip patch antenna and completely cover the N79 frequency band; A second metal short-circuit post group is provided on both sides of the right-angle side away from the L-shaped microstrip patch antenna of the square microstrip patch antenna; the second metal short-circuit post group is used to add a resonant frequency point to the square microstrip patch antenna and widen the operating bandwidth of the square microstrip patch; A third metal short-circuit post group is provided between the gap between the L-shaped microstrip patch antenna and the square microstrip patch antenna; the third metal short-circuit post group is used to improve the isolation between each feed port.

9. The design method of the MIMO array antenna based on a three-port antenna module according to claim 8, characterized in that, Several metal short-circuit pillars in the first metal short-circuit pillar group penetrate the L-shaped microstrip patch antenna, the main dielectric substrate, and the air layer from top to bottom, and contact the metal ground; several metal short-circuit pillars in the second and third metal short-circuit pillar groups penetrate the main dielectric substrate and the air layer from top to bottom, and contact the metal ground.

10. The design method of the MIMO array antenna based on a three-port antenna module according to claim 8, characterized in that, When the number of the three-port antenna modules is 4, the four three-port antenna modules are respectively located at the four corners of the main dielectric substrate; the two end edges of the L-shaped microstrip patch antenna of any three-port antenna module coincide with the edge of the main dielectric substrate.

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