8*8 ultra-wideband MIMO (Multiple Input Multiple Output) mobile phone antenna

Abstract

The invention discloses an 8 * 8 ultra-wideband MIMO (Multiple Input Multiple Output) mobile phone antenna, and relates to the technical field of ultra-wideband. The two groups of antenna array elements correspond to each other, the antenna array elements are located on the substrate, each group of antenna array elements comprises four signal pieces with the same specification, and the four signal pieces are arranged in a circumferential array; the signal piece excites the antenna in a coaxial line back feed mode. According to the 8 * 8 ultra-wideband MIMO mobile phone antenna, due to the fact that the antenna units are orthogonally placed and designed, under the condition that an extra decoupling structure is not introduced, the isolation degree reaches-15dB or below, the ECC is lower than 0.01, the-10dB bandwidth of the antenna reaches 3.3-5.9 GHz, full coverage of 5G and WLAN frequency bands is achieved, the comprehensive performance of the antenna is excellent, and the antenna can be widely applied to the field of mobile phones. The technical problem that an existing mobile phone antenna is complex in structure and poor in applicability when used is effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of ultra-wideband technology, and particularly to an 8×8 ultra-wideband MIMO mobile phone antenna. Background Art

[0002] Ultra-wideband technology usually adopts a carrierless pulse system, and obtains rich spectrum information through the characteristics of ultra-wideband. In the fields of through-wall imaging, ground penetrating radar, ultra-wideband communication, etc., ultra-wideband technology has extensive applications. Through-wall imaging radar has characteristics such as fast and efficient, non-invasive detection, etc., and ultra-wideband communication has advantages such as large capacity, high rate, high safety factor, etc. In recent decades, with the rapid development of electronic devices, ultra-wideband technology has also been widely applied in the national economy and municipal construction.

[0003] Currently, a Chinese patent with the patent application number "CN201610956556.7" discloses a 4×4 ultra-wideband MIMO antenna, belonging to the field of wireless communication technology. It is composed of four monopole ultra-wideband antenna units, two rectangular mesh cross-shaped isolation structures and a dielectric board. The four monopole ultra-wideband antenna structures are the same, and the four antennas are respectively at the four top corners of the dielectric board. Two antennas on one diagonal are flipped by 180 degrees, and the antennas on one horizontal line are flipped by 90 degrees. The whole is centrosymmetric with respect to the center of the dielectric board, and the two rectangular mesh cross-shaped isolation structures are respectively at the centers of the front and back sides of the dielectric board, and are symmetric up and down with respect to the dielectric board. By introducing this new type of mesh isolation structure into the MIMO antenna, the antenna obtains excellent isolation performance. Although this patent can be applied to various small mobile terminals, due to its complex structure and the limitation of the feeding method, the processing difficulty is large.

[0004] However, during the implementation of the above technical solution, it is found that at least the following technical problems exist:

[0005] Complex structure and poor applicability: When the existing ultra-wideband MIMO mobile phone antenna is in use, since its external uses an additional decoupling structure, it will bring redundant current radiation, not only losing power, but also destroying the original radiation pattern. Secondly, the feeding methods of the existing mobile phone antennas are all side feeding, resulting in very large limitations during production and processing; in addition, coplanar waveguides are all used, which is prone to interference. Therefore, we propose an 8×8 ultra-wideband MIMO mobile phone antenna. Summary of the Invention

[0006] (1) Technical problems to be solved

[0007] In view of the deficiencies of the prior art, the present invention provides an 8×8 ultra-wideband MIMO mobile phone antenna, which solves the technical problems of complex structure and poor applicability existing in the existing mobile phone antenna during use.

[0008] (2) Technical Solution

[0009] To achieve the above object, the present invention is implemented through the following technical solutions:

[0010] An 8×8 ultra-wideband MIMO mobile phone antenna, which includes:

[0011] A substrate in a rectangular shape;

[0012] Two groups of corresponding antenna elements, and the antenna elements are located on the substrate. Each group of antenna elements includes four signal elements with the same specifications, and the four signal elements are arranged in a circular array;

[0013] Among them, the signal element excites the antenna in a coaxial back-feed manner, and the signal element includes a defective ground plane and an ultra-wideband antenna unit respectively attached to the front and back sides of the substrate. The defective ground plane and the ultra-wideband antenna unit are connected to each other, and the surfaces of the defective ground plane and the ultra-wideband antenna unit are both grooved.

[0014] Preferably, the two groups of antenna elements are centrosymmetric about the center point on the surface of the substrate.

[0015] Preferably, the ultra-wideband antenna unit is connected to the terminal on the defective ground plane through a microstrip feeder on it.

[0016] Preferably, the grooving process of the defective ground plane includes a trapezoidal through-hole opened at the center of the defective ground plane, and the upper base and the lower base of the trapezoidal through-hole are parallel to each other. A plurality of first rectangular grooves are symmetrically opened on the lower base of the trapezoidal through-hole;

[0017] Among them, the distance between the upper base of the trapezoidal through-hole and the edge of the defective ground plane is 3 mm.

[0018] Preferably, the ultra-wideband antenna unit includes a radiation patch in the shape of an equilateral trapezoid, and the grooving process of the ultra-wideband antenna unit includes a plurality of end rectangular grooves opened on the lower base of the radiation patch and side rectangular grooves opened on both sides of the radiation patch;

[0019] Among them, the number of the end rectangular grooves is three groups;

[0020] The side rectangular grooves are two groups and are respectively located on both sides of the radiation patch. The two groups of side rectangular grooves are not at the same horizontal height.

[0021] Preferably, the three groups of end rectangular grooves have the same specifications, with a width of 1 mm and a depth of 1.6 mm.

[0022] Preferably, the widths of the two groups of side rectangular grooves are both 1 mm, and the distance from one group of side rectangular grooves to the upper base of the radiation patch is 7 mm, and the distance from the other group to the upper base of the radiation patch is 4 mm;

[0023] Among them, the distance from the two groups of the side rectangular grooves to the symmetric center line of the radiation patch is 2 mm for both.

[0024] (III) Beneficial effects

[0025] Since the antenna units are orthogonally placed, the isolation reaches below -15 dB without introducing an additional decoupling structure, and the -10 dB bandwidth of the antenna reaches 3.3 - 5.9 GHz. Therefore, it effectively solves the technical problems of the existing mobile phone antennas, such as complex structure and poor applicability. Secondly, the evaluation index of the traditional technology is only -6 dB, while this patent adopts a more stringent -10 dB, achieving full coverage of the 5G band, with the isolation reaching below -15 dB and the ECC being lower than 0.01. All the above performance indicators meet or exceed the performance indicators of the listed antennas, and the comprehensive performance of the proposed antenna is superior. Description of the drawings

[0026] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and describes them in detail in conjunction with the drawings as follows.

[0027] Figure 1 It is the front structure diagram of the whole of the embodiment of the present invention;

[0028] Figure 2 It is the back structure diagram of the whole of the embodiment of the present invention;

[0029] Figure 3 It is the schematic diagram of the front and back flipping of the embodiment of the present invention;

[0030] Figure 4 It is the front structure diagram of the signal member in the embodiment of the present invention;

[0031] Figure 5 It is the back structure diagram of the signal member in the embodiment of the present invention;

[0032] Figure 6 It is the size structure diagram of the antenna unit in the embodiment of the present invention;

[0033] Figure 7 It is the physical and measured field diagram of the MIMO antenna in the embodiment of the present invention;

[0034] Figure 8 It is the S-parameter simulation diagram of the MIMO antenna in the embodiment of the present invention;

[0035] Figure 9 It is the S-parameter measured diagram of the MIMO antenna in the embodiment of the present invention;

[0036] Figure 10This is the simulated and measured radiation patterns of the MIMO antenna in the embodiments of the present invention.

[0037] Legend:

[0038] 1. Substrate

[0039] 21. Defective ground plane; 211. First rectangular slot; 22. Ultra-wideband antenna element; 221. Radiation patch; 222. End rectangular slot; 223. Side rectangular slot; 224. Microstrip feeder; 225. Terminal. Specific implementation

[0040] In the embodiments of the present application, by providing an 8×8 ultra-wideband MIMO mobile phone antenna, the technical problems of complex structure and poor applicability existing in the existing mobile phone antennas during use are solved. When the existing mobile phone antennas are used, due to the orthogonal placement design of the antenna elements, the isolation reaches below -15 dB without introducing additional decoupling structures, and the -10 dB bandwidth of the antenna reaches 3.3 - 5.9 GHz. Secondly, the evaluation index adopted in the traditional technology is only -6 dB, while this patent adopts the more stringent -10 dB, achieving full coverage of the 5G frequency band, with the isolation reaching below -15 dB and the ECC below 0.01. The above performance indicators all reach or exceed the performance indicators of the listed antennas, and the comprehensive performance of the proposed antenna is superior.

[0041] Based on the characteristic mode theory, an ultra-wideband 8×8 multiple-input multiple-output (MIMO) antenna for mobile phones using fifth-generation (5G) communication technology is proposed. This antenna can be integrated into the mobile phone back cover without occupying internal space. By effectively exciting the TM 10 mode, a -10 dB bandwidth of 3.23 - 6 GHz is generated, with a relative bandwidth as high as 70%, fully covering the 5G N77 / N78 / N79 and WLAN frequency bands. The orthogonal design enables the antenna to have an isolation below -15 dB without adding any decoupling structures, the envelope correlation coefficient (ECC) below 0.01, and the voltage standing wave ratio (VSWR) below 1.58. Throughout the frequency band, the radiation efficiency of the antenna reaches about 90%. Further simulation shows that when the antenna is held or not, the antenna performance hardly changes. The overall size of the antenna is 154×74×1.5 mm 3 , which conforms to the size of a conventional mobile phone. The processing and testing show that the S-parameters and radiation performance of the antenna all reach or exceed the simulation design, and the measured and simulation results are in good agreement, as follows:

[0042] Embodiment: The technical solution in the embodiments of the present application is to solve the technical problems of complex structure and poor applicability existing in the existing mobile phone antennas during use. The general idea is as follows:

[0043] Aiming at the problems existing in the prior art, the present invention provides an 8×8 ultra-wideband MIMO mobile phone antenna, and the overall size of the mobile phone antenna is 154×74×1.5 mm 3 , fabricated on a printed circuit board, and the substrate material is FR-4, ε r =4.4, tanδ = 0.02. The radiation patch and the defect ground are located on the upper and lower surfaces of the substrate respectively. On the substrate, 8 units are arranged in an orthogonal polarization diversity manner, and the design is symmetrical up, down, left and right. The numbers of the antenna units are marked on the figure. Each antenna unit is excited by a coaxial backfeed method. After grooving the radiation patch and the ground, the antenna bandwidth can be fine-tuned so that it can still completely cover the 5G low-frequency part when forming a MIMO array, as Figure 1-6 shown. The specific structure is as follows:

[0044] A rectangular substrate 1;

[0045] Two groups of corresponding antenna elements, and the two groups of antenna elements are centrosymmetric with respect to the center point on the surface of the substrate 1, and the antenna elements are located on the substrate 1. Each group of antenna elements includes four signal components with the same specifications, and the four signal components are arranged in a circular array;

[0046] Among them, the signal components use the coaxial backfeed method to excite the antenna, and the signal components include a defect ground 21 (the purpose of the defect ground is to construct a self-complementary structure, and the self-complementary structure is one of the common broadband antennas) and an ultra-wideband antenna element 22 that are respectively attached to the front and back sides of the substrate 1. The ultra-wideband antenna element 22 is connected to the terminal 225 on the defect ground 21 through the microstrip feeder 224 thereon. The defect ground 21 and the ultra-wideband antenna element 22 are connected to each other, and grooving treatments are performed on the surfaces of both the defect ground 21 and the ultra-wideband antenna element 22.

[0047] First, the grooving treatment of the defect ground 21 includes a trapezoidal through-hole opened at the center of the defect ground 21, and the upper bottom edge and the lower bottom edge of the trapezoidal through-hole are parallel to each other. A plurality of first rectangular grooves 211 are symmetrically opened on the lower bottom edge of the trapezoidal through-hole, and the distance between the upper bottom edge of the trapezoidal through-hole and the edge of the defect ground 21 is 3 mm.

[0048] Second, the ultra-wideband antenna element 22 includes a radiation patch 221 in the shape of an equilateral trapezoid, and the grooving treatment of the ultra-wideband antenna element 22 includes a plurality of end rectangular grooves 222 opened on the lower bottom edge of the radiation patch 221 and side rectangular grooves 223 opened on both sides of the radiation patch 221;

[0049] Among them, the number of the end rectangular grooves 222 is three groups. The specifications of the three groups of end rectangular grooves 222 are the same, with a width of 1 mm and a depth of 1.6 mm. The side rectangular grooves 223 are two groups and are respectively located on both sides of the radiation patch 221. The two groups of side rectangular grooves 223 are not at the same horizontal height. The widths of the two groups of side rectangular grooves 223 are both 1 mm. The distance from one group of side rectangular grooves 223 to the upper bottom edge of the radiation patch 221 is 7 mm, and the distance from the other group to the upper bottom edge of the radiation patch 221 is 4 mm. The distances from the two groups of side rectangular grooves 223 to the symmetry center line of the radiation patch 221 are both 2 mm. The specific experimental steps are as follows:

[0050] It can be seen from Figure 8 that the reflection coefficient of the proposed 5G ultra-wideband MIMO antenna fully meets the requirements, completely covering the 3.3 - 5.9 GHz frequency band required by 5G N77 / N78 / N79 and WLAN. Without adding any decoupling structure, the isolation of the MIMO antenna reaches below -15 dB. Since the antenna covers the WLAN frequency band, to a certain extent, the number of mobile phone antennas is reduced and space is saved. The detailed dimensions of the antenna are as Figure 5 and Figure 6 marked. Since the 8 antenna units are placed orthogonally and symmetrically, only four units, namely antenna units 1, 2, 5, and 6, are simulated.

[0051] To verify the performance indicators of the proposed MIMO antenna, the antenna was fabricated in this paper. The physical objects are as Figure 4 and Figure 5 shown. The S-parameters and far-field radiation characteristics of the antenna were measured by using a vector network analyzer and a microwave anechoic chamber respectively. By comparing the measured and simulated data, it can be seen that the performance indicators of the antenna basically meet the design requirements.

[0052] The S-parameters were measured by the "Siyee (ceyear) 3671" vector network analyzer. The test site is as Figure 7 (c) shown. As Figure 9 shown, except for antenna unit 2, the -10 dB bandwidth in the figure fully covers 3.3 - 5.9 GHz. The reflection coefficients of antenna unit 2 near 4.6 GHz and 4.8 GHz are about -9.7 dB, which are mainly caused by the processing and testing errors. In addition, the fluctuation phenomenon of the measured data is caused by the environmental electromagnetic interference at the test site. However, within the entire frequency band, the transmission coefficients between the antenna units are still all less than -17 dB, which is better than the simulation results. This indicates that the isolation performance between the antenna units is excellent, and the simulation and measured results are in good agreement. This antenna has a certain practical value.

[0053] The far-field radiation performance of the antenna was measured by using the NSI2000 ANTENNA MEASUREMENT SYSTEM in a microwave anechoic chamber. The test site is asFigure 7 As shown in (d), since the antenna elements are exactly the same, antenna element 1 was randomly selected as the test object, and the measured results are as follows Figure 10 As shown, since the MIMO antenna covers a relatively wide frequency band, the frequency point intervals are relatively large, which are 3.5 GHz, 4.4 GHz, and 5.3 GHz respectively. Through HFSS simulation, the MIMO antenna in the YOZ plane, E φ shows omnidirectional radiation, and in the XOZ plane, E θ shows "8"-shaped radiation, which is basically the same as the pattern of a single antenna element, indicating that the array formation has little impact on the radiation performance of the antenna element. The results measured in the anechoic chamber are basically the same as the simulation results. The slight fluctuation phenomenon is caused by factors such as environmental electromagnetic interference and inaccurate placement of the antenna under test. In the range of 3.3 - 5.9 GHz, the proposed antenna not only achieves impedance ultra-wideband but also basically achieves beam ultra-wideband. By comparing the patterns of the three frequency points, it can be seen that the pattern shapes are basically the same. The Eφ in the XOZ plane and Eθ in the YOZ plane of the MIMO antenna are cross-polarized signals, and the signal strength is relatively weak, and the measurement error is relatively larger, and the fluctuation is particularly obvious. To show the radiation performance, normalization processing was done in Figure 10 all of them.

[0054] Figure 9 Shown are the ECC, VSWR, and Efficiency of the MIMO antenna. It can be seen from the figure that the maximum value of the ECC of the proposed antenna is less than 0.01, far lower than the 0.4 index of the MIMO antenna, and the correlation between antenna elements is extremely low. The VSWR value of the antenna is also very small. Generally speaking, when the VSWR value of the MIMO antenna is less than 1.7, it meets the requirements, while the maximum VSWR of the proposed antenna is less than 1.58, and the impedance matching of the antenna is also very good. Throughout the frequency band, the efficiency of the antenna reaches about 90%. The performance of this antenna fully meets the design requirements.

[0055] An ultra-wideband 5G 8×8 MIMO mobile phone antenna is proposed in this paper. The antenna element is a conical dipole antenna designed and optimized based on the characteristic mode theory. The antenna element selects the TM10 mode from the potential modes of the square patch antenna as the excitation mode. The feeding designed for this mode enables the bandwidth of the antenna element to reach 3.23 - 6 GHz, and -10 dB is used as the evaluation index. An 8×8 MIMO 5G mobile phone antenna is composed of these antenna elements. The antenna elements adopt an orthogonal placement design, and the isolation reaches below -15 dB without introducing additional decoupling structures. The -10 dB bandwidth of the antenna reaches 3.3 - 5.9 GHz. To verify the performance of the antenna, the antenna is processed and tested. The test shows that the S-parameters and radiation performance both reach or exceed the simulation design, and the measured results are in good agreement with the simulation. The ECC and VSWR of the antenna reach 0.01 and 1.58 respectively, and the Efficiency reaches 90%. Finally, the influence of the human hand on the radiation performance of the antenna is also simulated and analyzed. The simulation shows that whether the antenna is held or not has little effect on the antenna performance, and the S-parameters can still meet the design requirements. The proposed antenna shows great potential application value in 5G mobile phones.

[0056] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. 8×8 Ultra-wideband MIMO Mobile Phone Antenna, characterized in that, The mobile phone antenna includes: A substrate (1) in a rectangular shape; Two groups of corresponding antenna elements, and the antenna elements are located on the substrate (1). Each group of antenna elements includes four signal components with the same specifications, and the four signal components are arranged in a circular array; Among them, the signal components excite the antenna in the way of coaxial backfeeding. The signal components include a defect ground plane (21) and an ultra-wideband antenna unit (22) respectively attached to the front and back sides of the substrate (1). The defect ground plane (21) is connected to the ultra-wideband antenna unit (22), and the surfaces of the defect ground plane (21) and the ultra-wideband antenna unit (22) are both grooved to expand the bandwidth and increase the isolation degree through the grooving process.

2. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 1, characterized in that: The two groups of the antenna elements are centrosymmetric about the center point on the surface of the substrate (1).

3. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 1, characterized in that: The ultra-wideband antenna unit (22) is connected to the terminal (225) on the defect ground plane (21) through the microstrip feeder (224) thereon.

4. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 1, characterized in that: The grooving process of the defect ground plane (21) includes a trapezoidal through-hole opened at the center of the defect ground plane (21). The upper bottom edge and the lower bottom edge of the trapezoidal through-hole are parallel to each other, and a plurality of first rectangular grooves (211) are symmetrically opened on the lower bottom edge of the trapezoidal through-hole; Among them, the distance between the upper bottom edge of the trapezoidal through-hole and the edge of the defect ground plane (21) is 3 mm.

5. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 1, characterized in that: The ultra-wideband antenna unit (22) includes a radiation patch (221) in the shape of an equilateral trapezoid. The grooving process of the ultra-wideband antenna unit (22) includes a plurality of end rectangular grooves (222) opened on the lower bottom edge of the radiation patch (221) and side rectangular grooves (223) opened on both sides of the radiation patch (221); Among them, the number of the end rectangular grooves (222) is three groups; The side rectangular grooves (223) are two groups and are respectively located on both sides of the radiation patch (221). The two groups of the side rectangular grooves (223) are not at the same horizontal height.

6. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 5, characterized in that: The three groups of the end rectangular grooves (222) have the same specifications, with a width of 1 mm and a depth of 1.6 mm.

7. The 8×8 ultra-wideband MIMO mobile phone antenna according to claim 5, characterized in that: The widths of the two groups of the side rectangular grooves (223) are both 1 mm. The distance from one group of the side rectangular grooves (223) to the upper bottom edge of the radiation patch (221) is 7 mm, and the distance from the other group to the upper bottom edge of the radiation patch (221) is 4 mm; Among them, the distances from the two groups of the side rectangular grooves (223) to the symmetry center line of the radiation patch (221) are both 2 mm.

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