8-unit dual-frequency MIMO antenna applied to 5G smart phone

Abstract

The application provides an 8-unit dual-frequency MIMO array antenna applied to a 5G smart phone, which comprises a horizontal dielectric substrate, a vertical dielectric substrate, a radiation patch, a decoupling unit, a microstrip line and a feed port, a ground plane is printed on the bottom surface of the horizontal dielectric substrate, the radiation patch is connected with the ground plane through a short-circuit part of the radiation patch, the radiation patch is printed on the inner side of the left and right vertical dielectric substrates, the radiation patch is fed through the microstrip line, the microstrip line is printed on the upper surface of the horizontal dielectric substrate and is connected with the radiation patch, and the decoupling unit is printed on the outer side of the left and right vertical dielectric substrates and is arranged between the radiation units. The application provides an 8-unit MIMO antenna applied to a 5G smart phone, which has the advantages of simple structure, small size, low profile, low coupling, high gain and large channel capacity.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to an 8-element dual-frequency MIMO antenna for use in 5G smartphones. Background Technology

[0002] Antennas, as key components of wireless communication devices for transmitting and receiving electromagnetic waves, have been widely used in military, civilian, and industrial production fields. Especially with the widespread adoption of smartphones, antennas have become an indispensable tool for acquiring and transmitting information in daily life. As people's demands for a high-quality life continue to grow, antennas, as crucial components for transmitting and receiving information in various wireless communication devices, will undoubtedly receive continued attention from scholars in related fields.

[0003] With the progress and development of human society, the volume of mobile communication services has exploded. However, the mobile cellular systems and related antenna equipment in fourth-generation (4G) wireless communication technology cannot meet the ever-increasing demand. Compared with 4G systems, fifth-generation (5G) mobile communication technology can provide ultra-fast speeds, ultra-low latency, and extremely high reliability. Therefore, significantly improving the channel capacity of mobile terminal device antennas has become imperative. Multiple-input multiple-output (MIMO) technology is one of the key technologies for achieving the ultra-high channel capacity of 5G. The new frequency bands allocated to 5G can be divided into sub-6GHz and millimeter-wave bands. Among them, sub-6GHz utilizes bandwidth resources below 6GHz to develop 5G. Currently, the sub-6GHz frequency bands confirmed for use in the initial construction of 5G in my country include 3.6-3.8GHz and 4.8-5.0GHz. Because the wavelength of the sub-6GHz band is much longer than that of the millimeter-wave band, it is easier to solve the signal coverage problem over a large area. Millimeter waves have wider bandwidth, faster speed, and larger channel capacity, allowing more people to access the internet simultaneously. However, this frequency band has a relatively small coverage area and higher cost, making it suitable for densely populated areas.

[0004] For 5G MIMO array antennas for mobile wireless communication devices, scholars from various countries have proposed some different schemes, such as inverted-F antenna (PIFA) and microstrip antenna. In the paper "Wideband MIMO Antenna Array Design for Future Mobile Devices Operating in the 5G NRF frequency Bands n77 / n78 / n79 and LTE Band 46", the authors designed an 8-element PIFA antenna with an element size of 13.9mm × 7mm. In the paper "AWideband PIFA-Pair-Based MIMO Antenna for 5G Smartphones", the authors proposed a 4-element PIFA antenna with an element size of 15mm × 7mm. Both of these antennas are ultra-wideband antennas covering 5G N76 / N77 / N78 and LTE 46, and have low isolation. However, the excessively wide bandwidth makes them susceptible to interference from other signals in practical operation. In the paper "High-isolation eight-element MIMO array for 5G smartphone applications", the authors proposed an 8-element dipole MIMO antenna for the 3.45GHz band (3.3–3.6GHz) with an isolation of 20dB. However, this antenna has a single frequency band and a large size. Therefore, designing a dual-frequency 5G MIMO array antenna with simple structure, small size, low profile, low coupling, and large channel capacity has high application value. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide an 8-element dual-band MIMO antenna for use in 5G smartphones.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] An 8-element dual-band MIMO antenna for 5G smartphones includes: a horizontal dielectric substrate, a vertical dielectric substrate, a radiating patch, a decoupling unit, a microstrip line, and a feed port;

[0008] A ground plane is printed on the top of the horizontal dielectric substrate. The radiating patch and the ground plane are connected through a short-circuit portion of the radiating patch. The radiating patch is printed on the inner side of the two vertical dielectric substrates on the left and right sides. The decoupling unit is printed on the outer side of the two vertical dielectric substrates on the left and right sides and is placed between two adjacent radiating units. The radiating patch and the decoupling unit are located on the inner and outer sides of the vertical dielectric substrates, respectively. The decoupling unit has an inverted L-shaped structure. The vertical arm of the decoupling unit is connected to the ground plane, and the horizontal arm of the decoupling unit is flush with the upper edge of the vertical dielectric substrate. The radiating patch has a rectangular structure. The rectangular structure is divided into three parts by slots, which are rotated clockwise from the short-circuit branch to form a first part, a second part, and a third part. The first part and the second part are both L-shaped structures, and the third part is an inverted U-shaped structure. The first part is connected to the short-circuit branch and is connected to the ground plane using a short-circuit probe. The third part is connected to a microstrip line, and the microstrip line is connected to the feed port.

[0009] Preferably, the first part and the second part, as well as the second part and the third part, are separated by slots.

[0010] Preferably, the horizontal dielectric substrate and the two vertical dielectric substrates constitute a U-shaped structure of the mobile phone casing; the two vertical dielectric substrates have the same structure.

[0011] Preferably, the horizontal dielectric substrate and the two vertical dielectric substrates are made of epoxy resin with a relative permittivity of 4.4; the thickness of the vertical dielectric substrate is 0.8 mm; and the thickness of the horizontal dielectric substrate is 1.0 mm.

[0012] Preferably, the radiating patch, the ground plane, the decoupling unit, and the microstrip line are all made of metallic materials.

[0013] Preferably, the microstrip line is a 50Ω impedance-matched microstrip line.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] This invention provides an 8-element dual-band MIMO antenna for 5G smartphones. It employs coaxial feeding, utilizes microstrip lines to achieve 50Ω impedance matching for easy installation, and leverages slotting technology to reduce antenna size while achieving dual-band characteristics. A short-circuit probe loading method further reduces the antenna's size. By dividing the radiating surface into three parts using slot loading technology, the antenna achieves dual-band and wideband characteristics, with impedance bandwidths of 3.18-3.62 GHz (center frequencies of 3.25 GHz) and 4.73-5.31 GHz (center frequencies of 5.1 GHz), achieving relative bandwidths of 13.53% and 11.37%, respectively. This effectively addresses the impact of the complex electromagnetic environment inside smartphones on antenna radiation performance. Furthermore, the minimum return loss at the center frequency points reaches -51.2 dB and -30.4 dB, respectively, indicating good impedance matching. Within the aforementioned frequency bands, the antenna's radiation characteristics meet industrial application standards for smartphones, namely, a return loss of less than -6 dB and a voltage standing wave ratio (VSWR) of less than 3 for MIMO antenna arrays. The center frequency and bandwidth of the dual-band antenna can be adjusted by adjusting the length and width of the inverted U-shaped opening in the third part or the length and width of the long side of the inverted L-shaped patch in the first part; the decoupling unit is placed on the outside of the vertical dielectric substrate, which reduces the coupling between antenna elements, and the maximum coupling between antennas is reduced from -9dB to -14dB. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the radiating patch structure of the array antenna unit according to an embodiment of the present invention;

[0018] Figure 2 This is a side view structural diagram of an embodiment of the present invention;

[0019] Figure 3 This is a top view structural diagram of an embodiment of the present invention;

[0020] Figure 4 This is a three-dimensional structural diagram of an embodiment of the present invention;

[0021] Figure 5 The diagram shows the return loss curves of antenna elements 1, 2, 3, and 4 of the MIMO antenna array in the simulation of a mobile phone structure in this embodiment of the invention.

[0022] Figure 6The graph shows the radiation efficiency curves of antenna elements 1, 2, 3, and 4 of the MIMO antenna array in the simulation of a mobile phone structure in this embodiment of the invention.

[0023] Figure 7 This is a schematic diagram of the envelope correlation coefficient (ECC) between adjacent antenna elements on one side of the MIMO antenna array in the simulation of a simulated mobile phone structure in an embodiment of the present invention.

[0024] Figure 8 This is a schematic diagram of the return loss curve between adjacent antenna elements on one side of the MIMO antenna array in the simulation of a simulated mobile phone structure in an embodiment of the present invention.

[0025] Figure 9 This is a current amplitude distribution diagram of the antenna at a center frequency of 3.4 GHz in an embodiment of the present invention;

[0026] Figure 10 This is a current amplitude distribution diagram of the antenna at a center frequency of 5.15 GHz in an embodiment of the present invention;

[0027] Figure 11 This is the radiation pattern of the antenna array in the simulation of a mobile phone structure at 3.14 GHz, as shown in this embodiment of the invention.

[0028] Figure 12 This is the radiation pattern of the antenna array in the simulation of a mobile phone structure at 5.15 GHz, as shown in this embodiment of the invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Radiating patch short-circuit branch; 2. Radiating patch first part; 3. Radiating patch second part; 4. Radiating patch third part; 5. Microstrip line feed; 6. First slot; 7. Second slot; 8. Third slot; 9. Fourth slot; 10. Fifth slot; 11. Sixth slot; 12. Seventh slot; 13. Vertical dielectric substrate; 14. Ground plane; 15. Horizontal dielectric substrate; 16. First decoupling unit; 17. Second decoupling unit; 18. Third decoupling unit; Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, including a series of steps, processes, methods, etc., is not limited to the steps listed, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products, or devices.

[0034] like Figure 1 As shown, an 8-element dual-band MIMO antenna for 5G smartphones consists of: 1. a radiating patch short-circuit branch; 2. a first part of the radiating patch; 3. a second part of the radiating patch; 4. a third part of the radiating patch; and 5. a microstrip line feed, which together form the basic antenna element.

[0035] The 8-element dual-band MIMO antenna for 5G smartphones described herein will be introduced using only one side of the dielectric substrate 13 and its elements, as the vertical dielectric substrate 13 and its inner and outer element structures are symmetrical.

[0036] like Figure 2 , 3 As shown in Figure 4, an 8-element dual-band MIMO antenna for 5G smartphones includes: a vertical dielectric substrate 13, a horizontal dielectric substrate 15, a ground plane 14, a first decoupling unit 16, a second decoupling unit 17, a third decoupling unit 18, and... Figure 1 The antenna basic unit shown is composed of a decoupling unit on the outside of the dielectric substrate 13 and a radiating patch on the inside of the dielectric substrate 13, both of which are connected to the ground plane 14.

[0037] The vertical dielectric substrate 13 has the following printed on its inner side: Figure 1 The radiating patch shown has a vertical dielectric substrate 13 with dimensions of 150mm × 6mm × 0.8mm, a horizontal dielectric substrate 15 with dimensions of 150mm × 70mm × 1mm, and a ground plane 14 with dimensions of 150mm × 70mm. Figure 1The dimensions of the first decoupling unit 16 are 14mm × 5mm, the dimensions of the short-circuit branch 1 are 2.2mm × 1mm, the dimensions of the microstrip line feed 5 are 2mm × 1mm, and the dimensions of the horizontal rectangles in the first decoupling unit 16, the second decoupling unit 17, and the third decoupling unit 18 are 12mm × 1.5mm and the dimensions of the vertical rectangles are 0.5mm × 5.5mm.

[0038] The horizontal dielectric substrate 15 has a ground plane 14 printed on its bottom surface and is connected to the dielectric substrate 13 on both sides. The horizontal dielectric substrate 15 and the vertical dielectric substrate 13 form a U-shaped structure. Four pairs of antenna radiating elements are evenly arranged on the inner side of the dielectric substrate 13. Figure 1 Decoupling units are uniformly placed on the outer side of the dielectric substrate 13, and the decoupling units are positioned in the center of the gap between adjacent antenna radiating units. The radiating unit patch is connected to the ground plane 14 and the short-circuit branch through a metal via.

[0039] The radiation patch ( Figure 1 Starting from the short-circuit branch, the radiating patch is divided into three different parts in a clockwise direction. The three parts 2, 3, and 4 are not connected to each other through gap loading technology. The first part 2 is connected to the short-circuit branch 1 and grounded to the ground plane 14. The third part 4 is connected to the microstrip line feed 5.

[0040] The first decoupling unit 16, the second decoupling unit 17, and the third decoupling unit 18 are inverted L-shaped structures and are placed on the outside of the dielectric substrate 13. The top edge of the horizontal rectangle (12mm×1.5mm) is flush with the top edge of the outer side of the dielectric substrate 13, and the bottom edge of the vertical rectangle (0.5mm×5.5mm) is connected to the ground plane 14. The decoupling units 16, 18, and 17 have different directions but the same structure.

[0041] The radiation unit ( Figure 1 The ground plane 14, the first decoupling unit 16, the second decoupling unit 17 and the third decoupling unit 18 are all made of metal materials, and the vertical dielectric substrate 13 and the horizontal dielectric substrate 15 are both made of epoxy resin (FR4).

[0042] One embodiment of the present invention is as follows:

[0043] The vertical dielectric substrate 13 and the horizontal dielectric substrate 15 are cuboid in shape, and the material used is epoxy resin with a relative permittivity of 4.4. The dielectric substrate 13 has dimensions of 150mm × 6mm × 0.8mm, and the horizontal dielectric substrate 15 has dimensions of 150mm × 70mm × 1mm.

[0044] like Figure 1As shown, eight different rectangular slots are added clockwise along the bottom of the radiating patch, dividing the radiating unit into three parts: the sixth slot 11 above the first short-circuit branch 1 has a size of 0.8mm × 0.7mm; the fifth slot 10 has a size of 4mm × 0.3mm; the first slot 6 has a size of 11.6mm × 0.3mm; the second slot 7 has a size of 2.5mm × 0.3mm; the fourth slot 9 has a size of 10.5mm × 0.3mm; the seventh slot 12 has a size of 2.1mm × 0.8mm; and the third slot 8 has a size of 7.5mm × 1mm.

[0045] like Figure 2 As shown, the horizontal rectangles of decoupling units 16, 17, and 18 have dimensions of 12mm × 1.5mm, and the vertical rectangles have dimensions of 0.5mm × 5.5mm. The long and short sides are placed vertically to form an L-shaped structure.

[0046] Figure 3 , Figure 4 These are, respectively, a top view and a three-dimensional view of the overall antenna structure. Figure 4 In the example, on one side, the distances of ant1 and ant4 from the two edges of the dielectric substrate 13 are 15mm and 16mm respectively. The spacing between adjacent radiating elements of ant1-ant4 is approximately 21mm. The first decoupling unit 16, the second decoupling unit 17, and the third decoupling unit 18 are placed outside the dielectric substrate 13, between adjacent radiating elements. Their function is to reduce the coupling between antenna radiating elements.

[0047] Figure 5 This example shows the return loss curves of four antenna elements on one side of an 8-element dual-band MIMO antenna used in a 5G smartphone. According to the 8-element MIMO antenna protocol, the return loss value is required to be less than -6dB. Figure 5 In the middle, S 11 S 22 S 33 and S 44 The design meets the engineering application requirement of less than -6dB return loss in the 3.18-3.62GHz and 4.73-5.31GHz frequency bands. Therefore, this embodiment achieves a broadband dual-band design, meeting the domestic 5G standards for 3.3-3.6GHz and 4.8-5.0GHz under the Sub 6GHz protocol.

[0048] Figure 6 The simulation results show the radiation efficiency of an 8-element dual-frequency MIMO antenna used in a 5G smartphone in this example. It can be seen that the radiation efficiency of the four antenna elements on one side is higher than 60%, which is excellent.

[0049] Figure 7The envelope correlation coefficient (ECC) between adjacent antenna elements on one side of an 8-element dual-frequency MIMO antenna applied to a 5G smartphone is shown in the simulation of a simulated mobile phone structure in an embodiment of the present invention. It can be seen that the ECC between adjacent antenna elements is less than 0.04.

[0050] Figure 8 This is a return loss curve between adjacent antenna elements on one side of an 8-element dual-band MIMO antenna applied to a 5G smartphone in a simulated mobile phone structure, according to an embodiment of the present invention. It can be seen that the isolation S between adjacent antenna elements... 21 S 32 and S 43 All less than 14dB;

[0051] Figure 9 , Figure 10 The figures show the current amplitude distribution of the antenna in this embodiment at center frequencies of 3.4 GHz and 5.15 GHz, respectively. It can be seen that at a center frequency of 3.4 GHz, the current is mainly distributed in the first structure 2 and the second structure 3; at a center frequency of 5.15 GHz, the current is mainly distributed in the third structure 4.

[0052] Figure 11 , Figure 12 The diagram shows the radiation patterns of the antenna in this embodiment at center frequencies of 3.4 GHz and 5.15 GHz. In the diagram, E represents the electric field and H represents the magnetic field. It can be seen from the diagram that the antenna radiation pattern of this embodiment performs well in the H-plane, meeting the actual engineering requirements of mobile devices during use. The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0053] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention.

[0054] In conclusion, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An 8-element dual-band MIMO antenna for use in 5G smartphones, characterized in that, include: Horizontal dielectric substrate, vertical dielectric substrate, radiating patch, decoupling unit, microstrip line and feed port; A ground plane is printed on the top of the horizontal dielectric substrate. The radiating patch and the ground plane are connected through a short-circuit portion of the radiating patch. The radiating patch is printed on the inner side of the two vertical dielectric substrates on the left and right. The decoupling unit is printed on the outer side of the two vertical dielectric substrates on the left and right and is placed between two adjacent radiating units. The radiating patch and the decoupling unit are located on the inner and outer sides of the vertical dielectric substrates, respectively. The decoupling unit has an inverted L-shaped structure. The vertical arm of the decoupling unit is connected to the ground plane, and the horizontal arm of the decoupling unit is flush with the upper edge of the vertical dielectric substrate. The radiating patch has a rectangular structure. The radiating patch is divided into three parts by slots in the rectangular structure, which are rotated clockwise from the short-circuit branch to form a first part, a second part, and a third part. The first part and the second part are both L-shaped structures, and the third part is an inverted U-shaped structure. The first part is connected to the short-circuit branch and is connected to the ground plane using a short-circuit probe. The third part is connected to the microstrip line, and the microstrip line is connected to the feed port. The first part, the second part, and the third part are not connected to each other through gap loading technology.

2. The 8-element dual-band MIMO antenna for 5G smartphones according to claim 1, characterized in that, The horizontal dielectric substrate and the two vertical dielectric substrates constitute a U-shaped structure for the mobile phone casing; the two vertical dielectric substrates have the same structure.

3. The 8-element dual-band MIMO antenna for 5G smartphones according to claim 1, characterized in that, The horizontal dielectric substrate and the two vertical dielectric substrates are made of epoxy resin with a relative permittivity of 4.4; the thickness of the vertical dielectric substrate is 0.8 mm; and the thickness of the horizontal dielectric substrate is 1.0 mm.

4. The 8-element dual-band MIMO antenna for 5G smartphones according to claim 1, characterized in that, The radiating patch, the ground plane, the decoupling unit, and the microstrip line are all made of metallic materials.

5. The 8-element dual-band MIMO antenna for 5G smartphones according to claim 1, characterized in that, The microstrip line is a 50Ω impedance-matched microstrip line.

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