A dual-band eight-element multiple-input multiple-output (MIMO) antenna for 5G mobile phones

Abstract

The present invention discloses a dual-band eight-unit multiple-input multiple-output (MIMO) antenna for 5G mobile phones, comprising a rectangular dielectric substrate, characterized in that a metal floor is provided at the bottom of the rectangular dielectric substrate, and M "T"-shaped grooves and K convex grooves are symmetrically cut on the surface of the floor; N "U"-shaped antenna units are evenly provided on the top of the dielectric substrate, and each antenna unit is composed of three microstrip lines; the microstrip lines are composed of metal material and loaded on the top of the dielectric substrate, and the microstrip line structure is provided with a feeding point; the antenna units on both sides of the top of the dielectric substrate are distributed in a mirror-symmetrical manner, and the distance between the antenna units on each side is the same. The present invention can cover the 3.3GHz-3.6GHz and 4.8GHz-5.0GHz frequency bands, with an isolation between each port better than 13.6dB, a radiation efficiency of more than 50%, and an envelope correlation coefficient of less than 0.08. The antenna has a simple structure, is easy to process, and has low cost, and has high practical value in mobile terminal applications.

Description

Technical Field

[0001] The present invention relates to the field of 5G mobile communication technology, and in particular to a dual-band eight-element multiple-input multiple-output (MIMO) antenna for 5G. Background Art

[0002] Mobile communications are entering the 5G era. Compared to 4G, 5G offers higher speeds, lower latency, more connections, faster mobility, and enhanced security. Communication system theory shows that greater channel capacity increases data transmission rates, and Multiple-Input Multiple-Output (MIMO) technology can significantly improve channel capacity and transmission rates. Research has shown that in multipath environments, channel capacity increases exponentially with increasing the number of transmit and receive antennas.

[0003] Extensive research has been conducted both domestically and internationally on broadband MIMO antennas for 5G communication systems. However, most 5G antennas designed and researched only cover a limited frequency band. This single, narrow frequency band hinders communication, making multi-band antenna implementation a key issue.

[0004] In November 2017, China's Ministry of Industry and Information Technology announced the designation of the 3.3GHz-3.6GHz and 4.8GHz-5.0GHz frequency bands for 5G mobile communications. Therefore, to meet 5G communication standards, designing a dual-band MIMO antenna capable of covering both 3.5GHz and 4.9GHz is crucial.

[0005] The purpose of the present invention is to provide an eight-element multiple-input multiple-output (MIMO) antenna for 5G dual-band; compared with traditional antennas, the invention has the advantages of simple structure, wide bandwidth and good isolation.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0007] A dual-band eight-element multiple-input multiple-output (MIMO) antenna for 5G mobile phones includes a rectangular dielectric substrate. Its characteristics are: a metal floor is provided at the bottom of the rectangular dielectric substrate, and M "T"-shaped grooves and K convex grooves are symmetrically cut on the surface of the floor; N "U"-shaped antenna units are evenly provided on the top of the dielectric substrate, and each antenna unit is composed of three microstrip lines; the microstrip lines are composed of metal material and loaded on the top of the dielectric substrate. The microstrip line structure is provided with a feeding point; the antenna units on both sides of the top of the dielectric substrate are distributed in mirror symmetry, and the distance between the antenna units on each side is the same.

[0008] Preferably, the cuboid serves as a dielectric substrate, the microstrip line is used for feeding the antenna, and the M “T”-shaped slots and K convex slots are used to improve the impedance matching performance of the antenna.

[0009] Preferably, the rectangular dielectric substrate is made of FR4 with a dielectric constant of 4.4, a length of 150 mm, a width of 75 mm, and a height of 0.4 mm; the side with the printed metal microstrip line is the front side of the dielectric substrate, and the side with the printed metal floor is the back side of the dielectric substrate.

[0010] Preferably, the microstrip line is U-shaped and evenly and symmetrically distributed along the front side of the substrate, loaded above two parallel "T"-shaped grooves and convex grooves; the first microstrip line is 10 mm long and 0.75 mm wide, distributed in a direction parallel to the long side of the dielectric substrate; the second microstrip line is 3.5 mm long and 0.6 mm wide, connected to the first one perpendicularly, and distributed in a direction parallel to the short side of the dielectric substrate; the third microstrip line is connected to the second one perpendicularly, distributed in a direction parallel to the long side of the dielectric substrate, with a length of 2 mm and a width of 0.4 mm.

[0011] Preferably, the "T"-shaped slot is composed of two slots, one of which is distributed in an "I" shape along the long side of the dielectric substrate, with a length of 18 mm and a width of 2.4 mm; the other slot is square, connected to the left side of the long side of the "I"-shaped slot, with a length and width of 0.45 mm, and connected to the edge of the metal floor.

[0012] Preferably, the convex groove is distributed parallel to the "T"-shaped groove and consists of two "I"-shaped grooves; one of the "I"-shaped grooves is 18 mm long and 2.3 mm wide; the other "I"-shaped groove is connected to the middle inner side of the first groove and is convex, with a length of 4 mm and a width of 0.8 mm; the "T"-shaped groove and the convex groove are symmetrically distributed along the metal floor.

[0013] Preferably, the rightmost side of the T-shaped groove and the leftmost side of the adjacent convex groove are spaced 4.5 mm apart.

[0014] Preferably, the back surface of the dielectric substrate is tin-coated according to a floor structure, and the front surface of the dielectric substrate is tin-coated according to a microstrip line structure.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The antenna of the present invention is fed from the bottom by a 50Ω coaxial line and is used for antenna patches covering the 5G dual frequency bands of 3.3GHz-3.6GHz and 4.8GHz-5.0GHz.

[0017] (2) The antenna of the present invention can cover the target frequency band, the isolation between each port is better than 13.6dB, the envelope correlation coefficient is less than 0.08, and it has good diversity performance.

[0018] (3) The antenna of the present invention has the advantages of simple structure, easy processing, low cost and high channel capacity, and has high practical value in mobile terminal applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attached photos Figure 1 It is a schematic diagram of the system structure of the present invention.

[0020] Figure 2 It is a structural diagram of the antenna unit of the present invention.

[0021] Figure 3 This is a diagram of the dielectric plate grounding structure of the present invention.

[0022] Figure 4 3 is a comparison diagram of the simulated and measured S parameters of the antennas Ant1, Ant2, Ant3 and Ant4 of the present invention.

[0023] Figure 5 This is a comparison diagram of the simulation and actual measurement of the antenna unit isolation of the present invention.

[0024] Figure 6 3.5 GHz is a comparison diagram of the simulated and measured radiation directions of the antennas Ant1, Ant2, Ant3 and Ant4 of the present invention at 3.5 GHz.

[0025] Figure 7 3 is a comparison diagram of the simulated and measured radiation directions of the antennas Ant1, Ant2, Ant3 and Ant4 of the present invention at 4.9 GHz.

[0026] Figure 8 This is a diagram showing the calculation results of the correlation coefficient between antenna units of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further explained below by specific examples, but the present invention is not limited to these specific embodiments. Those skilled in the art should appreciate that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0028] like Figure 1As shown, a dual-band eight-element multiple-input, multiple-output (MIMO) antenna for 5G includes a dielectric substrate 1 with a metal floor 3 at its bottom. Sixteen slots of a specific shape are provided on the surface of the floor 3. The entire dielectric substrate is 150 mm long, 75 mm wide, and 0.4 mm high. Eight U-shaped microstrip lines 2 are loaded on top of the dielectric substrate 1, with the four on the left mirror-symmetric with the four on the right. The U-shaped microstrip lines 2 are composed of three microstrip lines 4, 5, and 6 connected alternately and perpendicularly to each other, each of which is provided with a feeding point 7 for power feeding. T-shaped slots 8 and convex slots 9 are cut at the bottom of the floor 3 to improve the impedance matching performance of the antenna. The present invention has a simple structure, is easy to process, is low in cost, and has high channel capacity.

[0029] The microstrip line 2 is composed of 4, 5, and 6. 4 is distributed in a direction parallel to the long side of the dielectric substrate; 5 is perpendicularly connected to 4 and distributed in a direction parallel to the short side of the dielectric substrate; and 6 is perpendicularly connected to 5 and distributed in a direction parallel to the long side of the dielectric substrate.

[0030] Each “T”-shaped slot 8 is composed of a square slot 10 and an “I”-shaped slot 11 connected in parallel, and is provided below each microstrip line 2 .

[0031] The convex groove 9 is composed of an “I”-shaped groove 12 and an “I”-shaped groove 13 connected in parallel, and is arranged below each microstrip line 2.

[0032] In this embodiment, the microstrip line 4 has a length of 10 mm and a width of 0.75 mm, and is located on the top of the dielectric substrate; the microstrip line 5 has a length of 3.5 mm and a width of 0.6 mm, and is located on the top of the dielectric substrate; the microstrip line 6 has a length of 2 mm and a width of 0.4 mm, and is located on the top of the dielectric substrate.

[0033] The length of the "I"-shaped groove 11 in the "T"-shaped groove 8 is 18 mm, and the width is 2.4 mm; the length and width of the square groove 10 are both 0.45 mm;

[0034] The length of the "I"-shaped groove 13 in the convex groove 9 is 18 mm, and the width is 2.3 mm; the length of the "I"-shaped groove 12 in the protruding portion is 4 mm, and the width is 0.8 mm.

[0035] The distance between the rightmost side of the T-shaped groove on the floor and the leftmost side of the adjacent convex groove is 4.5 mm.

[0036] The antenna structure described in this example is etched on a dielectric substrate 1. The dielectric substrate is made of FR4 with a dielectric constant of 4.4 and a height of 0.4 mm. One side is tinned according to the structure of a microstrip line; the other side is tinned according to the structure of a floor, serving as an infinite ground plane.

[0037] The specific implementation is as follows:

[0038] This embodiment adopts circuit board etching technology to etch a pattern on one side of a 0.4mm thick PCB board. Figure 3 The ground plane structure of the entire dielectric substrate is 150mm×75mm×0.4mm. The etching technology is also used to etch a ground plane on the other side of the 0.4mm thick FR4 substrate. Figure 1 microstrip line structure.

[0039] The MIMO system was simulated using the electromagnetic simulation software ANSYS Electronics Desktop 2018.2. After the simulation and debugging were completed, the physical product was manufactured and tested. The results of the S parameters are shown in the attached figure. Figure 4 As shown in the figure, both simulation and test results show coverage of the 5G frequency bands of 3.3GHz-3.6GHz and 4.8GHz-5.0GHz. Because the designed antenna array is mirror-symmetrical, all measured elements can cover the 5G frequency bands of 3.3GHz-3.6GHz and 4.8GHz-5.0GHz, meeting the requirements of 5G mobile communications. As can be seen from the figure, the measured antenna resonance point is offset. This is because the half-hole process is used between the antenna ground point and the feed point, which widens the microstrip line slightly and causes the resonance point to shift.

[0040] As attached Figure 5 As shown in the figure, the isolation between antenna elements obtained by simulation and measurement is better than 13.6dB, indicating that the degree of coupling between antenna elements is very small.

[0041] As attached Figure 6 and attached Figure 7 The following plots compare the simulated and measured two-dimensional radiation patterns of Ant1, Ant2, Ant3, and Ant4 at the resonant frequencies of 3.5 GHz and 4.9 GHz, respectively, for the E-plane and H-plane. As can be seen from the figures, the designed antennas exhibit excellent radiation characteristics at both frequencies, meeting communication requirements. The discrepancies between the measured and simulated patterns may be due to manufacturing errors and manual measurement errors.

[0042] The smaller the envelope correlation coefficient between antenna units, the less influence the antenna units will have on each other when working independently, and the channel capacity will not be affected. Figure 8 As shown in FIG, the envelope correlation coefficient between antenna units is less than 0.08 in the 3.3 GHz-3.6 GHz and 4.8 GHz-5.0 GHz frequency bands. Therefore, the MIMO system has high independence and high practical value.

Claims

1. A dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone, comprising a rectangular parallelepiped dielectric substrate, characterized in that: A metal floor is provided at the bottom of the rectangular dielectric substrate, and M "T"-shaped grooves and K convex grooves are symmetrically cut on the surface of the floor; N "U"-shaped antenna units are evenly distributed on the top of the dielectric substrate; the antenna units on both sides of the top of the dielectric substrate are distributed in mirror symmetry, and the distance between the antenna units on each side is the same; The antenna is fed from the bottom by a 50Ω coaxial cable; The antenna units are U-shaped and evenly and symmetrically distributed along the front of the substrate, loaded above two parallel and symmetrically placed "T"-shaped slots and convex slots. Each antenna unit consists of three microstrip lines; the three microstrip lines are made of metal and loaded on top of the dielectric substrate. The first microstrip line is distributed in a direction parallel to the long side of the dielectric substrate; the second microstrip line is connected perpendicularly to the first microstrip line and distributed in a direction parallel to the short side of the dielectric substrate; the third microstrip line is connected perpendicularly to the second microstrip line and distributed in a direction parallel to the long side of the dielectric substrate; the second microstrip line is provided with a feeding point; The T-shaped slot consists of two slots, one of which is arranged in an I-shape along the long side of the dielectric substrate, with a length of 18 mm and a width of 2.4 mm. The other slot is square and connected to the left side of the long side of the I-shaped slot, with a length and width of 0.45 mm and connected to the edge of the metal floor. The convex groove is distributed parallel to the "T"-shaped groove and consists of two "I"-shaped grooves; one of the "I"-shaped grooves is 18mm long and 2.3mm wide; the other "I"-shaped groove is connected to the middle inner side of the first groove and is convex, with a length of 4mm and a width of 0.8mm.

2. A dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone according to claim 1, characterized in that: The cuboid serves as a dielectric substrate, the second microstrip line is used for feeding the antenna, and the M "T"-shaped slots and K convex slots are used to improve the impedance matching performance of the antenna.

3. A dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone according to claim 2, characterized in that: The rectangular dielectric substrate is made of FR4 with a dielectric constant of 4.4, a length of 150 mm, a width of 75 mm, and a height of 0.4 mm; the side with the printed metal microstrip line is the front side of the dielectric substrate, and the side with the printed metal floor is the back side of the dielectric substrate.

4. A dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone according to claim 3, characterized in that: The first microstrip line is 10 mm long and 0.75 mm wide; the second microstrip line is 3.5 mm long and 0.6 mm wide; and the third microstrip line is 2 mm long and 0.4 mm wide.

5. The dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone according to claim 1, characterized in that: The rightmost side of the T-shaped groove and the leftmost side of the adjacent convex groove are spaced 4.5 mm apart.

6. A dual-band eight-element multiple-input multiple-output (MIMO) antenna for a 5G mobile phone according to claim 5, characterized in that: The back side of the dielectric substrate is tin-coated according to the structure of a floor, and the front side of the dielectric substrate is tin-coated according to the structure of a microstrip line.

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