Compact low-profile circular MIMO antenna suitable for new mobile communication field

Abstract

The invention discloses a compact low-profile circular MIMO (Multiple Input Multiple Output) antenna suitable for the new mobile communication field, an air layer exists between a dielectric substrate and a metal ground plane in the antenna structure, six fan-shaped radiation units are uniformly printed on the dielectric substrate, gaps exist between the radiation units, and the radiation units are uniformly printed on the dielectric substrate. Each radiation unit comprises a feed short pin and two grounding short pins, and the grounding short pins are connected with the radiation unit and the metal ground plane; the isolation hole is etched on the metal ground plane right below the feed short needle; the feed short needles are inserted into the corresponding isolation holes through the air layer; the defected ground structure groove is etched on the metal ground plane right below the gap and points to the circle center from the circumference, and the part connected with the circumference is subjected to opening treatment. The MIMO antenna obtains excellent impedance matching and isolation, excellent radiation performance is achieved on the premise that the low profile of the antenna is guaranteed, the structure is simple, and the processing cost is low.

Description

Technical Field

[0001] The present invention belongs to the field of mobile communication technology, and relates to a low-profile, miniaturized, multi-band supported microstrip patch antenna using MIMO technology, and specifically to a compact low-profile circular MIMO antenna suitable for the new mobile communication field. Background Art

[0002] With the rapid development of mobile communications, the technology of high-speed and high-quality data transmission is also being updated and iterated. In the future, the quality and rate of signal transmission, as well as the number of devices connected simultaneously, will develop rapidly. In 2023, the Ministry of Industry and Information Technology of China issued a new version of the "Regulations on Radio Frequency Allocation of the People's Republic of China", which clearly allocated the 6.425 to 7.125 GHz frequency band for international mobile communications (IMT, including 5G and 6G systems). This frequency band is the only high-quality resource with large bandwidth in the mid-frequency band, with the characteristics of wide coverage and large capacity, and is therefore particularly suitable for the deployment of 5G or future 6G systems.

[0003] As a carrier of communication technology, the function of the antenna also needs to be updated and iterated quickly. In the face of significantly improved communication rates and capacities in the future, the requirements for antennas are more about achieving better communication quality and greater data throughput. Among the many antenna technologies, Multiple-Input Multiple-Output (MIMO) technology has become a key technology for wireless communication systems.

[0004] MIMO antennas improve communication technology by first sending different data streams simultaneously on different antennas, allowing the system's data transmission volume to increase exponentially with the number of antennas, significantly improving the data transmission rate. Furthermore, MIMO antennas can improve performance by allowing multiple antennas to send the same data. If part of the data fades during the transmission process, the signals of other antennas can compensate for its impact, thereby improving the quality of the received signal. However, in mobile terminals or portable devices with limited size, the application of MIMO antennas still has the following problems:

[0005] 1. Integrating multiple antennas in a small space such as a mobile device will increase the coupling between them. As the number of antennas increases, the distance between antennas in the originally limited space is shortened. Each antenna will be interfered by the induced current of the adjacent antenna, which will cause the diversity performance and impedance matching of the MIMO antenna to be negatively affected. Therefore, additional decoupling structures need to be added.

[0006] 2. As mobile devices become thinner and thinner, a few tenths of a millimeter improvement can bring huge improvements in both commercial and industrial fields. Therefore, as an important component of mobile devices, the thickness of the antenna is particularly important. The thinner the antenna, the more competitive it will be in the application of new communication fields in the future. However, low-profile antennas and the use of high-loss substrates may lead to lower efficiency.

[0007] As mentioned above, the MIMO antennas used in mobile devices have very high requirements for both horizontal and vertical dimensions. In order to solve such problems, existing research efforts on the horizontal space of MIMO antennas are mainly focused on achieving a decoupling structure that does not affect the size of the antenna. This part of the design will increase the overall complexity of the antenna to a certain extent, affecting processing efficiency and is not conducive to cost control. As for the vertical space, if you want to reduce the thickness of the antenna without affecting other performance of the antenna, you need to make trade-offs in other structures, such as reducing additional structures that affect the thickness of the antenna, or sacrificing some performance, and using a substrate with lower loss.

[0008] In summary, the current antennas suitable for mobile devices need to add decoupling structures to reduce the coupling between multiple antenna elements, but this will increase the size of the antenna to a certain extent. Most decoupling methods that do not affect the size require complicating the antenna design, and the requirement for a low profile will affect the radiation performance of the antenna to a certain extent. Therefore, it is still a huge challenge to design an antenna with high isolation and high radiation performance in a limited space while meeting the requirements of miniaturization in size. Summary of the invention

[0009] The purpose of the present invention is to address the deficiencies in the prior art and propose a compact, low-profile circular MIMO antenna suitable for the new mobile communication field. While keeping the antenna units compact, good isolation can be achieved between ports, and the antenna's high efficiency can be maintained while achieving a low profile. The overall structural design is simple, and its operating frequency band can cover the new international mobile communication frequency band of 6.425-7.125 GHz and the new WiFi-6E frequency band of 5.925-7.125 GHz, making it very suitable as an antenna for mobile communication devices that will work in these frequency bands in the future.

[0010] The present invention discloses a compact low-profile circular MIMO antenna suitable for new mobile communications fields, the structure includes the following key features:

[0011] (1) Multiple-input multiple-output (MIMO) technology: By integrating multiple antennas on the same substrate, channel capacity and communication quality are improved. (2) Multi-band support: The antenna supports the new international mobile communication band of 6.425-7.125 GHz and the new WiFi-6E band of 5.925-7.125 GHz. (3) Low-profile design: The antenna structure is simple and compact. Using FR-4 substrate, the overall thickness of the antenna is only 1.3 mm. (4) Decoupling design: By etching defective ground structure grooves on the ground plane of adjacent ports, the isolation of adjacent ports can be improved without affecting the size of the antenna patch, helping the antenna to meet the requirements of miniaturization.

[0012] In order to achieve the object of the present invention, the present invention adopts the following scheme:

[0013] A compact low-profile circular MIMO antenna suitable for the new mobile communication field comprises: a dielectric substrate, a radiation unit printed on the front of the dielectric substrate, a feeding unit, a metal ground plane, an isolation hole etched on the metal ground plane, a defective ground structure groove etched on the metal ground plane, and a grounding short pin connecting the radiation unit and the metal ground plane.

[0014] There is an air layer between the dielectric substrate and the metal ground plane.

[0015] The radiation units include a first radiation unit, a second radiation unit, a third radiation unit, a fourth radiation unit, a fifth radiation unit, and a sixth radiation unit.

[0016] There are gaps between the first to sixth radiation units.

[0017] The feeding unit includes a first feeding short pin, a second feeding short pin, a third feeding short pin, a fourth feeding short pin, a fifth feeding short pin, and a sixth feeding short pin.

[0018] The isolation holes include a first isolation hole, etched on a metal ground plane directly below the first feed short pin; a second isolation hole, etched on a metal ground plane directly below the second feed short pin; a third isolation hole, etched on a metal ground plane directly below the third feed short pin; a fourth isolation hole, etched on a metal ground plane directly below the fourth feed short pin; a fifth isolation hole, etched on a metal ground plane directly below the fifth feed short pin; and a sixth isolation hole, etched on a metal ground plane directly below the sixth feed short pin.

[0019] The defective ground structure grooves include a first defective ground structure groove, a second defective ground structure groove, a third defective ground structure groove, a fourth defective ground structure groove, a fifth defective ground structure groove, and a sixth defective ground structure groove.

[0020] The grounding short pin includes a first grounding short pin, connecting the first radiation unit and the metal ground plane; a second grounding short pin, connecting the first radiation unit and the metal ground plane; a third grounding short pin, connecting the second radiation unit and the metal ground plane; a fourth grounding short pin, connecting the second radiation unit and the metal ground plane; a fifth grounding short pin, connecting the third radiation unit and the metal ground plane; a sixth grounding short pin, connecting the third radiation unit and the metal ground plane; a seventh grounding short pin, connecting the fourth radiation unit and the metal ground plane; an eighth grounding short pin, connecting the fourth radiation unit and the metal ground plane; a ninth grounding short pin, connecting the fifth radiation unit and the metal ground plane; a tenth grounding short pin, connecting the fifth radiation unit and the metal ground plane; an eleventh grounding short pin, connecting the sixth radiation unit and the metal ground plane; and a twelfth grounding short pin, connecting the sixth radiation unit and the metal ground plane.

[0021] Preferably, the dielectric substrate is a cylindrical FR-4 substrate with a radius of 20 mm and a thickness of 0.3 mm.

[0022] Preferably, the metal ground plane is a circular metal copper plate with a radius of 22.5 mm.

[0023] Preferably, there are three gaps, which are placed crosswise with the intersection being the center of the dielectric substrate. The length of each gap is equal to the diameter of the dielectric substrate and the width is 1 mm. The radiation patch printed on the dielectric substrate is evenly divided into six equal parts to obtain six fan-shaped radiation units.

[0024] Preferably, the first feed short pin, the second feed short pin, the third feed short pin, the fourth feed short pin, the fifth feed short pin and the sixth feed short pin are all metal cylinders with a radius of 0.8 mm and a height of 1.3 mm. They are inserted into the corresponding isolation holes through the air layer, and the feed short pins are placed at the center line position of the corresponding radiation unit, 15.5 mm away from the center of the circle.

[0025] Preferably, the first isolation hole, the second isolation hole, the third isolation hole, the fourth isolation hole, the fifth isolation hole and the sixth isolation hole are all circular holes with a radius of 1 mm, etched on the metal ground plane to prevent the feeding unit from directly contacting the metal ground plane.

[0026] Preferably, the first defective ground structure groove, the second defective ground structure groove, the third defective ground structure groove, the fourth defective ground structure groove, the fifth defective ground structure groove and the sixth defective ground structure groove are all rectangular grooves with a length of 10 mm and a width of 0.4 mm, which are respectively etched on the metal ground plane directly below the 6 gaps separating the radiation units, starting from the circumference and pointing to the center of the circle, and the parts connected to the circumference are opened.

[0027] Preferably, the first ground short pin, the second ground short pin, the third ground short pin, the fourth ground short pin, the fifth ground short pin, the sixth ground short pin, the seventh ground short pin, the eighth ground short pin, the ninth ground short pin, the tenth ground short pin, the eleventh ground short pin and the twelfth ground short pin are all metal cylinders with a radius of 0.8 mm and a height of 1.3 mm. Two ground short pins are allocated to each radiation unit and are placed on the left and right sides of the fan-shaped center line of the radiation unit with an angle difference of 15° and a distance of 11.8 mm from the center of the circle.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention uses a ground short pin to adjust the resonance mode and a defective ground structure slot to improve the isolation of adjacent ports of the antenna, so that the MIMO antenna has excellent impedance matching and isolation, and the operating frequency band can cover the new international mobile communication frequency band of 6.425-7.125GHz and the new WiFi-6E frequency band of 5.925-7.125GHz. The present invention also achieves excellent radiation performance while ensuring the low profile of the antenna. The miniaturized structure is very suitable for new mobile communication technology equipment in future 5G or 6G systems. In addition, the present invention has a simple structure, low processing cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the top layer structure of the MIMO antenna system;

[0031] Figure 2 This is a schematic diagram of the bottom layer structure of the MIMO antenna system;

[0032] Figure 3 This is the left view of the MIMO antenna system;

[0033] Figure 4 It is the reflection coefficient S11 parameter simulation curve diagram of the MIMO antenna system in the working frequency band;

[0034] Figure 5 It is a simulation curve diagram of the transmission coefficient (isolation) of the MIMO antenna system in the working frequency band;

[0035] Figure 6 It is the ECC curve diagram of the MIMO antenna system in the working frequency band;

[0036] Figure 7 It is the gain curve diagram of the MIMO antenna system in the working frequency band;

[0037] Figure 8 It is the antenna efficiency curve of the MIMO antenna system in the working frequency band;

[0038] Fig. 9is the radiation pattern of this MIMO antenna system at 6.0GHz;

[0039] Fig.10 is the radiation pattern of this MIMO antenna system at 6.8GHz;

[0040] Markings in the figure: 0-1, dielectric substrate; 0-2, metal ground plane; 1-1, first radiating unit; 1-2, second radiating unit; 1-3, third radiating unit; 1-4, fourth radiating unit; 1-5, fifth radiating unit; 1-6, sixth radiating unit; 2-1, first feed short pin; 2-2, second feed short pin; 2-3, third feed short pin; 2-4, fourth feed short pin; 2-5, fifth feed short pin; 2-6, sixth feed short pin; 3-1, first isolation hole; 3-2, second isolation hole; 3-3, third isolation hole; 3-4, fourth isolation hole; 3-5, fifth isolation hole; 3-6, sixth isolation hole ;4-1, the first defective ground structure groove; 4-2, the second defective ground structure groove; 4-3, the third defective ground structure groove; 4-4, the fourth defective ground structure groove; 4-5, the fifth defective ground structure groove; 4-6, the sixth defective ground structure groove; 5-1, the first ground short pin; 5-2, the second ground short pin; 5-3, the third ground short pin; 5-4, the fourth ground short pin; 5-5, the fifth ground short pin; 5-6, the sixth ground short pin; 5-7, the seventh ground short pin; 5-8, the eighth ground short pin; 5-9, the ninth ground short pin; 5-10, the tenth ground short pin; 5-11, the eleventh ground short pin; 5-12, the twelfth ground short pin. DETAILED DESCRIPTION

[0041] A compact low-profile circular MIMO antenna suitable for new mobile communication fields, comprising:

[0042] A dielectric substrate, a radiation unit printed on the front side of the dielectric substrate, a feeding unit, a metal ground plane, an isolation hole etched on the metal ground plane, a defective ground structure groove etched on the metal ground plane, and a ground short pin connecting the radiation unit and the metal ground plane.

[0043] in:

[0044] like Figure 1 The radiation units include a first radiation unit 1-1, a second radiation unit 1-2, a third radiation unit 1-3, a fourth radiation unit 1-4, a fifth radiation unit 1-5, and a sixth radiation unit 1-6, all of which are placed on a circular dielectric substrate and are spaced 1 mm apart from each other.

[0045] The feeding unit includes a first feeding short pin 2-1, a second feeding short pin 2-2, a third feeding short pin 2-3, a first feeding short pin 2-4, a fifth feeding short pin 2-5, and a sixth feeding short pin 2-6, which serve as port 1 to port 6 respectively; the first feeding short pin is placed directly below the first radiating unit 1-1; the second feeding short pin is placed directly below the second radiating unit 1-2; the third feeding short pin is placed directly below the third radiating unit 1-3; the fourth feeding short pin is placed directly below the fourth radiating unit 1-4; the fifth feeding short pin 2-5 is placed directly below the fifth radiating unit 1-5; and the sixth feeding short pin 2-6 is placed directly below the sixth radiating unit 1-6.

[0046] The first ground short pin 5-1 and the second ground short pin 5-2 are placed directly below the first radiation unit 1-1; the third ground short pin 5-3 and the fourth ground short pin 5-4 are placed directly below the second radiation unit 1-2; the fifth ground short pin 5-5 and the sixth ground short pin 5-6 are placed directly below the third radiation unit 1-3; the seventh ground short pin 5-7 and the eighth ground short pin 5-8 are placed directly below the fourth radiation unit 1-4; the ninth ground short pin 5-9 and the tenth ground short pin 5-10 are placed directly below the fifth radiation unit 1-5; the eleventh ground short pin 5-11 and the twelfth ground short pin 5-12 are placed directly below the sixth radiation unit 1-6.

[0047] like Figure 2 The first isolation hole 3-1, the second isolation hole 3-2, the third isolation hole 3-3, the fourth isolation hole 3-4, the fifth isolation hole 3-5, and the sixth isolation hole 3-6 are all etched on the metal ground plane to prevent the feeding unit from directly contacting the metal ground plane.

[0048] The first defective ground structure groove 4-1, the second defective ground structure groove 4-2, the third defective ground structure groove 4-3, the fourth defective ground structure groove 4-4, the fifth defective ground structure groove 4-5, and the sixth defective ground structure groove 4-6 are all etched on the metal ground plane to block the induced current between adjacent ports and improve the isolation between adjacent ports.

[0049] like Figure 3 The dielectric substrate 0-1 is placed directly above the metal ground plane 0-2, with a 1mm air layer in between. The feeding short pin passes through the dielectric substrate, is connected to the radiating element, and passes through the isolation hole on the metal ground plane for coaxial feeding. The grounding short pin passes through the dielectric substrate, is connected to the radiating element and the metal ground plane, and is used to adjust the antenna resonance.

[0050] In order to reduce production costs, the dielectric substrate adopts a FR-4 substrate with a dielectric constant of 4.4 and a loss tangent value of 0.02. The dielectric substrate is a cylinder with a radius of 20 mm and a height of 0.3 mm.

[0051] The feeding unit, the radiation unit and the metal ground plane are all made of metal copper.

[0052] like Figure 4 As shown in the simulation, due to the symmetry of the ports, the reflection coefficients of the six feeding ports remain consistent, so only S11 of port 1 is shown. The -6dB operating frequency band (based on 3:1 VSWR) specified for mobile devices of the antenna of the present invention is 5.76-7.17 GHz, which can cover the new international mobile communication frequency band of 6.425-7.125 GHz and the new WiFi-6E frequency band of 5.925-7.125 GHz.

[0053] like Figure 5 As shown in the simulation, due to the symmetry of the ports, the isolation between port 1 and port 2 is equal to the isolation between port 1 and port 6, and the isolation between port 1 and port 3 is equal to the isolation between port 1 and port 5, so only the isolation S12 between port 1 and port 2, the isolation S13 between port 1 and port 3, and the isolation S14 between port 1 and port 4 are displayed. The isolation between the ports of the antenna of the present invention can be maintained above 10dB, where due to the isolation induced current effect of the defective ground structure groove, the isolation between the adjacent ports of port 1 and port 2 reaches 11dB; the isolation S13 between port 1 and port 3 reaches 18dB; and the isolation S14 between port 1 and port 4 reaches 14dB. The above data show that the coupling between the antenna ports of the present invention is low, and the channel independence can be guaranteed when working in a mobile device.

[0054] like Figure 6 As shown, ECC, or envelope correlation coefficient, represents the correlation between antenna units. The lower the ECC, the better the isolation of the MIMO antenna and the better the performance. The ECC of the present invention is less than 0.1, and most ECC parameters are even less than 0.01, which is far lower than the required value of the MIMO mobile phone antenna.

[0055] like Figure 7-Figure 8 As shown, the gain of the antenna of the present invention in the working frequency band is 3.47-5.26dBi, the antenna efficiency is 51-85%, and the efficiency is more than 70% at more than 74.5% of the frequency points in the working frequency band, which shows that the antenna has excellent performance. As a low-profile antenna, it can still maintain excellent gain and efficiency, ensuring the quality of signal strength, and is suitable for use in mobile devices.

[0056] like Figure 9-10 As shown, due to the symmetry of each port of the MIMO antenna, only the radiation pattern of port 1 is shown here. It can be seen that there is a significant difference between the main polarization and the cross polarization when the present invention is working, which shows that the polarization purity of the antenna is high, and each port is less interfered, which is conducive to the antenna to achieve high efficiency characteristics and excellent ECC.

[0057] The present invention adopts the design of grounding short pin and defective ground structure groove. Under the premise of not affecting the overall size of the antenna, the antenna resonance is stimulated by the grounding short pin, so that the antenna working frequency band is greatly widened, and the isolation of adjacent ports is optimized by blocking the induced current of adjacent ports through the defective ground structure groove. The present invention realizes a low-profile antenna with excellent radiation performance with a simple design. It not only occupies a small space, but also is easy to make and convenient to process. The new international mobile communication frequency band of 6.425-7.125GHz and the new WiFi-6E frequency band of 5.925-7.125GHz covered by it are both important frequency bands in the future mobile communication field. The invention has a high application value in the application of future mobile communication antennas.

[0058] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A compact low-profile circular MIMO antenna suitable for new mobile communications fields, characterized in that: It comprises a dielectric substrate (0-1), a radiation unit printed on the front of the dielectric substrate, a feeding unit, a metal ground plane (0-2), an isolation hole etched on the metal ground plane, a defective ground structure groove etched on the metal ground plane, and a grounding short pin connecting the radiation unit and the metal ground plane.

2. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 1, characterized in that: An air layer exists between the dielectric substrate (0-1) and the metal ground plane (0-2); The radiation units include a first radiation unit (1-1), a second radiation unit (1-2), a third radiation unit (1-3), a fourth radiation unit (1-4), a fifth radiation unit (1-5), and a sixth radiation unit (1-6); there are gaps between the first to sixth radiation units; The feeding unit comprises a first feeding short pin (2-1), a second feeding short pin (2-2), a third feeding short pin (2-3), a fourth feeding short pin (2-4), a fifth feeding short pin (2-5), and a sixth feeding short pin (2-6); The isolation holes include a first isolation hole (3-1) etched on a metal ground plane directly below a first feed short pin (2-1); a second isolation hole (3-2) etched on a metal ground plane directly below a second feed short pin (2-2); a third isolation hole (3-3) etched on a metal ground plane directly below a third feed short pin (2-3); a fourth isolation hole (3-4) etched on a metal ground plane directly below a fourth feed short pin (2-4); a fifth isolation hole (3-5) etched on a metal ground plane directly below a fifth feed short pin (2-5); and a sixth isolation hole (3-6) etched on a metal ground plane directly below a sixth feed short pin (2-6).

3. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 2, characterized in that: The grounding short pin comprises a first grounding short pin (5-1) connecting the first radiation unit (1-1) and the metal ground plane; a second grounding short pin (5-2) connecting the first radiation unit (1-1) and the metal ground plane; a third grounding short pin (5-3) connecting the second radiation unit (1-2) and the metal ground plane; a fourth grounding short pin (5-4) connecting the second radiation unit (1-2) and the metal ground plane; a fifth grounding short pin (5-5) connecting the third radiation unit (1-3) and the metal ground plane; and a sixth grounding short pin (5-6) connecting the third radiation unit (1-3) and the metal ground plane. a seventh grounding short pin (5-7) connecting the fourth radiation unit (1-4) and the metal ground plane; an eighth grounding short pin (5-8) connecting the fourth radiation unit (1-4) and the metal ground plane; a ninth grounding short pin (5-9) connecting the fifth radiation unit (1-5) and the metal ground plane; a tenth grounding short pin (5-10) connecting the fifth radiation unit (1-5) and the metal ground plane; an eleventh grounding short pin (5-11) connecting the sixth radiation unit (1-6) and the metal ground plane; and a twelfth grounding short pin (5-12) connecting the sixth radiation unit (1-6) and the metal ground plane.

4. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 3, characterized in that: The dielectric substrate is a cylindrical FR-4 material substrate with a radius of 20 mm and a thickness of 0.3 mm; The metal ground plane is a circular metal copper plate with a radius of 22.5 mm.

5. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 4, characterized in that: There are three gaps in total, which are placed crosswise with the intersection being the center of the dielectric substrate. The length of each gap is equal to the diameter of the dielectric substrate and the width is 1 mm. The radiation patch printed on the dielectric substrate is evenly divided into six equal parts to obtain six fan-shaped radiation units.

6. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 5, characterized in that: The first feed short pin (2-1), the second feed short pin (2-2), the third feed short pin (2-3), the fourth feed short pin (2-4), the fifth feed short pin (2-5), and the sixth feed short pin (2-6) are all metal cylinders with a radius of 0.8 mm and a height of 1.3 mm. They are inserted into the corresponding isolation holes through the air layer. The feed short pins are placed at the center line position of the corresponding radiation unit, 15.5 mm away from the center of the circle.

7. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 6, characterized in that: The first isolation hole (3-1), the second isolation hole (3-2), the third isolation hole (3-3), the fourth isolation hole (3-4), the fifth isolation hole (3-5), and the sixth isolation hole (3-6) are all circular holes with a radius of 1 mm, etched on the metal ground plane.

8. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 7, characterized in that: The defective ground structure grooves include a first defective ground structure groove (4-1), a second defective ground structure groove (4-2), a third defective ground structure groove (4-3), a fourth defective ground structure groove (4-4), a fifth defective ground structure groove (4-5), and a sixth defective ground structure groove (4-6), all of which are rectangular grooves with a length of 10 mm and a width of 0.4 mm, respectively etched on the metal ground plane directly below the six gaps separating the radiation units, starting from the circumference and pointing to the center of the circle, and the part connected to the circumference is opened.

9. A compact low-profile circular MIMO antenna suitable for new mobile communication fields according to claim 8, characterized in that: The first ground short pin (5-1), the second ground short pin (5-2), the third ground short pin (5-3), the fourth ground short pin (5-4), the fifth ground short pin (5-5), the sixth ground short pin (5-6), the seventh ground short pin (5-7), the eighth ground short pin (5-8), the ninth ground short pin (5-9), the tenth ground short pin (5-10), the eleventh ground short pin (5-11), and the twelfth ground short pin (5-12) are all metal cylinders with a radius of 0.8 mm and a height of 1.3 mm. Two ground short pins are allocated to each radiation unit and are respectively placed on the left and right sides of the fan-shaped center line of the radiation unit with an angle difference of 15° and a distance of 11.8 mm from the center of the circle.

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