5G high isolation MIMO mobile phone antenna

Abstract

The present invention discloses a fifth-generation mobile communication 5G high-isolation MIMO mobile phone antenna, which belongs to the field of mobile communication technology. The MIMO mobile phone antenna of the present invention includes eight circular slot antenna units with the same structure and symmetrically distributed on both sides; the circular slot antenna unit includes a dielectric substrate, a radiating microstrip line, a hexagonal parasitic slot structure, a ground plate and a coaxial connector. The MIMO antenna of the present invention improves the isolation without significantly increasing the size of the antenna by introducing a decoupling structure design; adopts an optimized antenna unit structure and overall layout to effectively reduce the additional loss caused by complex circuit design; covers the 5G mobile communication frequency band, ensuring excellent signal independence performance; has a small overall size, well adapted to the compact layout requirements of ultra-thin devices, and has achieved significant improvements in space occupancy and key frequency band performance, providing an ideal solution for high-density integration of 5G terminals.

Description

Technical Field

[0001] The present invention belongs to the field of mobile communication technology, and specifically relates to a fifth-generation mobile communication 5G high-isolation multiple-input multiple-output MIMO mobile phone antenna. Background Art

[0002] With the full commercialization of 5G technology, Multiple-Input Multiple-Output (MIMO) antennas have become a core technology for modern communication terminals, significantly improving channel capacity and data rates through spatial diversity. However, the continuous trend toward thinner, lighter, and more multifunctional devices has led to a sharp decrease in antenna design space. Highly densely packed antenna elements can induce strong mutual coupling, resulting in reduced isolation, lower radiation efficiency, and degraded envelope correlation coefficients (ECCs), severely limiting the actual performance of MIMO systems.

[0003] The existing technology, "Design of a High-Isolation 4-Element MIMO Mobile Phone Antenna for 5G," discloses a MIMO antenna operating in the 3.45-3.64 GHz frequency band. The antenna's four elements are placed at the corners of a 1.5 mm thick dielectric substrate. Parasitic circular slots are introduced to reduce coupling between elements. The resulting MIMO mobile phone antenna achieves isolation exceeding 18 dB, but its diversity performance still needs improvement.

[0004] The prior art, "An 8-element MIMO mobile phone antenna with T-shaped ground slot decoupling for 5G," discloses a MIMO mobile phone antenna with overall dimensions of 150mm × 75mm × 7mm, operating in the Sub-6G frequency band (5G NR N78). This antenna is coupled to an F-shaped radiating branch via an inverted L-shaped branch feeder. By aligning the resonant frequencies of the two branches of the F-shaped radiating branch, the operating bandwidth is broadened. Furthermore, a ground slot structure is used to achieve high antenna isolation. The designed MIMO mobile phone antenna achieves isolation exceeding 16.8dB in the 3.3-3.8GHz range, but its radiation gain is relatively low, and its isolation and diversity performance could be further optimized.

[0005] In summary, while existing technologies have partially mitigated the mutual coupling effect between units through techniques such as parasitic unit loading and defective ground structures, they still suffer from key performance deficiencies, such as poor diversity performance and low radiation gain. Therefore, a MIMO antenna design with a compact structure, excellent radiation performance, and high isolation is urgently needed to meet the requirements of 5G terminal devices. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a 5G high-isolation MIMO mobile phone antenna.

[0007] The technical problem proposed by the present invention is solved as follows:

[0008] A 5G high-isolation MIMO mobile phone antenna includes eight circular slot antenna units with the same structure; the eight circular slot antenna units are symmetrically distributed on both sides, and adjacent circular slot antenna units are closely arranged;

[0009] The annular slot antenna unit includes a dielectric substrate, a radiating microstrip line, a hexagonal parasitic slot structure, a ground plate, and a coaxial connector. The radiating microstrip line and the hexagonal parasitic slot structure are located on the upper surface of the dielectric substrate, and the ground plate is located on the lower surface of the dielectric substrate. The radiating microstrip line extends inward from the edge of the dielectric substrate and is perpendicular to the side of the dielectric substrate. The hexagonal parasitic slot structure is located on the axis of the radiating microstrip line, and a set of opposite sides are parallel to the side of the dielectric substrate. The ground plate has an annular slot, and the center of the annular slot is located on the axis of the radiating microstrip line. The outer conductor of the coaxial connector is connected to the ground plate, and the inner core is connected to the radiating microstrip line.

[0010] For a whole ground plate formed by connecting the ground plates of eight circular slot antenna units, a T-shaped slot is opened on the ground plate between adjacent circular slot antenna units on the same side; and a fence-shaped slot is opened at the horizontal axis of the whole ground plate.

[0011] Furthermore, the hexagonal parasitic slot structure has two symmetrically distributed groups of slots; the first group of slots extends from the corners of the hexagon to the center, perpendicular to the radiating microstrip line; the second group of slots extends from the middle position of the side not adjacent to the first group of slots to the center.

[0012] Furthermore, the long branches of the T-shaped slot are parallel to the radiating microstrip line, and the short branches are perpendicular to the radiating microstrip line.

[0013] Furthermore, the end of the radiating microstrip line and the hexagonal parasitic slot structure are located directly above the inner space of the annular gap.

[0014] Furthermore, the fence-shaped gap is symmetrical about the vertical axis of the entire ground plate, and the plurality of fences are unevenly distributed.

[0015] The beneficial effects of the present invention are:

[0016] The MIMO antenna of the present invention improves isolation to over 20 dB by introducing a decoupling structure design without significantly increasing the antenna size. Furthermore, the present invention employs an optimized antenna unit structure and overall layout, effectively reducing the additional losses caused by complex circuit design.

[0017] The MIMO antenna described in the present invention covers the N77 and N78 frequency bands of 5G mobile communications, with an ECC value of less than 0.001, far lower than the 0.45 required for 5G communications, ensuring excellent signal independence performance; the overall size is 150mm×75mm and the thickness is only 0.8mm, which can well adapt to the compact layout requirements of ultra-thin devices; compared with the existing technology, the present invention has achieved significant improvements in space occupancy and key frequency band performance, providing an ideal solution for high-density integration of 5G terminals. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the three-dimensional overall structure of the MIMO mobile phone antenna of the present invention;

[0019] Figure 2 This is a schematic diagram of the upper surface structure of the MIMO mobile phone antenna of the present invention;

[0020] Figure 3 This is a schematic diagram of the lower surface structure of the MIMO mobile phone antenna of the present invention;

[0021] Figure 4 This is a schematic structural diagram of the hexagonal parasitic slot structure in the MIMO mobile phone antenna of the present invention;

[0022] Figure 5 is an S-parameter curve diagram of the MIMO mobile phone antenna described in the embodiment;

[0023] Figure 6 A graph showing the low envelope correlation coefficient of the antenna unit in the MIMO mobile phone antenna according to the embodiment;

[0024] Figure 7 is the E-plane radiation pattern of the antenna unit in the MIMO mobile phone antenna described in the embodiment;

[0025] Figure 8 is the H-plane radiation pattern of the antenna unit in the MIMO mobile phone antenna described in the embodiment;

[0026] Figure 9 Graph showing the gain of the antenna unit in the MIMO mobile phone antenna according to the embodiment. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] This embodiment provides a 5G high isolation MIMO mobile phone antenna, and its three-dimensional overall structure diagram is as follows: Figure 1 As shown, the upper surface structure diagram is as follows Figure 2 As shown, the lower surface structure diagram is as follows Figure 3As shown, it includes eight circular slot antenna units with the same structure; the eight circular slot antenna units are symmetrically distributed on both sides, and adjacent circular slot antenna units are closely arranged;

[0029] The circular slot antenna unit includes a dielectric substrate 1, a radiating microstrip line 2, a hexagonal parasitic slot structure 3, a ground plate 4 and a coaxial connector; the radiating microstrip line 2 and the hexagonal parasitic slot structure 3 are located on the upper surface of the dielectric substrate 1, and the ground plate 4 is located on the lower surface of the dielectric substrate 1; the radiating microstrip line 2 extends inward from the edge of the dielectric substrate 1 and is perpendicular to the side of the dielectric substrate 1; the hexagonal parasitic slot structure 3 is located on the axis of the radiating microstrip line 2, with one set of opposite sides parallel to the side of the dielectric substrate 1 and two sets of symmetrically distributed slots are opened; Figure 4 As shown, the first group of slots extends from the corners of the hexagon toward the center, perpendicular to the radiating microstrip line 2; the second group of slots extends from the middle position of the side that is not adjacent to the first group of slots toward the center; the ground plate 4 is provided with a circular slot 5, the center of which is located on the axis of the radiating microstrip line 2, so that the end of the radiating microstrip line 2 and the hexagonal parasitic slot structure 3 are located directly above the internal space of the circular slot 5; the outer conductor of the coaxial connector is connected to the ground plate 4, and the inner core is connected to the radiating microstrip line 2.

[0030] For the entire ground plate composed of the ground plates 4 of eight circular slot antenna units, a T-shaped slot 6 is opened on the ground plate 4 between the adjacent circular slot antenna units on the same side, with the long branches parallel to the radiating microstrip line 2 and the short branches perpendicular to the radiating microstrip line 2; a fence-type slot 7 is opened at the horizontal axis of the entire ground plate, and the several fences on the fence-type slot 7 are not completely evenly distributed and are symmetrical about the vertical axis.

[0031] The annular slot antenna unit feeds the radiating microstrip line through a coaxial connector; the radiating microstrip line serves as the main loss-point structure and effectively radiates the fed RF signal. Due to the electromagnetic coupling effect, the current on the radiating microstrip line will generate an induced current at the edge of the annular slot. Specifically, the high-frequency current on the radiating microstrip line generates an alternating electromagnetic field around it, and this electromagnetic field will strongly couple with the annular slot below. The current coupled to the annular slot flows along the edge of the slot, forming a circular current path. Since the shape of the slot is annular, the current flows tangentially at the edge of the slot. This tangential current distribution gives the annular slot antenna unit an omnidirectional radiation characteristic, that is, the radiation intensity is relatively uniform on the plane where the annular slot antenna unit is located.

[0032] During the radiation process of the radiating microstrip line, the signal will encounter the hexagonal parasitic slot structure. The main function of the hexagonal parasitic slot structure is to reduce the coupling between the radiating microstrip line and the integrated components. When the signal passes through the radiating microstrip line, the hexagonal parasitic slot structure will guide the current to flow around it. Compared with the antenna without the introduction of this structure, the current density in the area near the feed port is significantly reduced after the hexagonal parasitic slot structure is introduced. This design method not only reduces the coupling between the radiating microstrip line and the components, but also suppresses the current density coupling between the radiating microstrip lines of adjacent circular slot antenna units, thereby improving the isolation of the antenna.

[0033] A T-shaped slot is introduced between adjacent circular slot antenna elements on the same side. By cutting the T-shaped slot in the ground plane, the current distribution on the ground plane is altered. Without the T-shaped slot, when a circular slot antenna element is excited, significant coupling current is induced in adjacent circular slot antenna elements, indicating strong mutual coupling between adjacent circular slot antenna elements on the same side. With the T-shaped slot, when a circular slot antenna element is excited, the surface current on the ground plane is confined to the periphery of the T-shaped slot, significantly reducing the coupling current between adjacent circular slot antenna elements on the same side. This indicates that the T-shaped slot significantly reduces the mutual coupling between adjacent circular slot antenna elements on the same side, improving isolation. A fence-shaped slot is further introduced between the circular slot antenna elements on both sides. The fence-shaped slot design can be viewed as stacking multiple T-shaped slots on the ground plane, further optimizing the current distribution and enhancing the decoupling effect.

[0034] In this embodiment, the radiating microstrip line 2 in the annular slot antenna unit is 8 mm long and 3 mm wide; the outer radius of the annular slot is 9.4 mm, the inner radius is 7.6 mm, and the distance between the center of the circle and the edge of the dielectric substrate 1 is 12.7 mm; the distance between the center of the hexagonal parasitic slot structure 3 and the edge of the dielectric substrate 1 is 13.5 mm, and the length of each side is 3 mm. The length of the first group of slots is 0.5 mm and the width is 0.2 mm, and the length of the second group of slots is 0.2 mm. m, with a width of 1.6mm; the short branch of the T-shaped slot 6 is 9.7mm long and 1mm wide, while the long branch is 0.4mm long and 4mm wide; the total width of the fence-shaped slot 7 is 150mm, with a length of 1mm; each fence is 4mm long and 0.5mm wide. The distance between the closest fence and the left edge of the dielectric substrate 1 is 20mm, the distance between the closest fence and the second closest fence is 20mm, and the distance between the closest fence and the third closest fence is 42mm. The dielectric substrate 1 is an FR4 substrate with a thickness of 0.8mm. The overall dimensions of the MIMO mobile phone antenna described in this embodiment are 150mm × 75mm, meeting the internal space requirements of the mobile phone.

[0035] The antenna described in this embodiment is simulated, and its S parameter curve is as follows: Figure 5 As shown in FIG, the ports of the eight circular slot antenna units are numbered 1 to 8, and S11 to S18 represent the transmission coefficients between ports 1 to 8 and port 1, respectively. Figure 5 It can be seen that the operating frequency band of the antenna described in this embodiment is 3.25 GHz to 3.86 GHz, covering the test frequency bands N77 and N78 of 5G mobile communications; the isolation is improved to more than 20 dB.

[0036] The low envelope correlation coefficient curve of the circular slot antenna unit is as follows: Figure 6 As shown, it can be seen that the low envelope correlation coefficient ECC value is less than 0.001, which meets the 5G communication requirements (ECC < 0.45).

[0037] The E-plane radiation pattern, H-plane radiation pattern and gain curve of the circular slot antenna unit are shown as follows: Figure 7 、 Figure 8 and Figure 9 As shown, it can be seen that its radiation pattern is symmetrical and stable, and the peak gain reaches 8.4~8.9 dBi.

[0038] In summary, the antenna described in this embodiment has a simple structure, a low profile, and occupies a small space. It is suitable for applications in 5G full-screen mobile phones, effectively solving the problems of large space occupation and insufficient performance in the existing technology, and providing an efficient and compact antenna solution for 5G terminal equipment. The antenna adopts a symmetrical layout, with a ring-shaped slot structure designed at the bottom, and a radiating microstrip line and a hexagonal parasitic slot structure configured on the front. In addition, T-shaped slots and fence-shaped slots are introduced between adjacent ring-shaped slot antenna units distributed on the same side and both sides, respectively, so that the isolation of the MIMO antenna is increased to more than 20 dB, and the envelope correlation coefficient ECC is less than 0.001, ensuring excellent signal independence performance. The peak gain of the ring-shaped slot antenna reaches 8.4-8.9 dBi, the radiation pattern is basically symmetrical, and it has good radiation characteristics.

Claims

1. A 5G high-isolation MIMO mobile phone antenna, characterized in that: It includes eight circular slot antenna units with the same structure; the eight circular slot antenna units are symmetrically distributed on both sides, and adjacent circular slot antenna units are closely arranged; The circular slot antenna unit comprises a dielectric substrate (1), a radiating microstrip line (2), a hexagonal parasitic slot structure (3), a ground plate (4) and a coaxial connector; the radiating microstrip line (2) and the hexagonal parasitic slot structure (3) are located on the upper surface of the dielectric substrate (1), and the ground plate (4) is located on the lower surface of the dielectric substrate (1); the radiating microstrip line (2) extends inward from the edge of the dielectric substrate (1) and is perpendicular to the side of the dielectric substrate (1); the hexagonal parasitic slot structure (3) is located on the lower surface of the dielectric substrate (1); On the axis where the radiating microstrip line (2) is located, a set of opposite sides are parallel to the sides of the dielectric substrate (1); the ground plate (4) is provided with a circular annular gap (5), and the center of the circular annular gap (5) is located on the axis where the radiating microstrip line (2) is located; the outer conductor of the coaxial connector is connected to the ground plate (4), and the inner core is connected to the radiating microstrip line (2); the hexagonal parasitic slot structure (3) is provided with two sets of symmetrically distributed gaps; the first set of gaps extends from the corners of the hexagon to the center and is perpendicular to the radiating microstrip line (2); The second set of gaps extends from the middle of the sides that are not adjacent to the first set of gaps toward the center; The end of the radiating microstrip line (2) and the hexagonal parasitic slot structure (3) are located directly above the inner space of the annular gap (5); For a whole ground plate formed by connecting the ground plates (4) of eight circular slot antenna units, a T-shaped slot (6) is opened on the ground plate (4) between adjacent circular slot antenna units on the same side; and a fence-shaped slot (7) is opened at the horizontal axis of the whole ground plate.

2. The 5G high isolation MIMO mobile phone antenna according to claim 1, characterized in that The long branches of the T-shaped slot (6) are parallel to the radiating microstrip line (2), and the short branches are perpendicular to the radiating microstrip line (2).

3. The 5G high isolation MIMO mobile phone antenna according to claim 1, characterized in that The fence-type gap (7) is symmetrical about the vertical axis of the entire ground plate, and a number of fences are unevenly distributed.

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