High-isolation dual-band MIMO antenna based on pattern cancellation method

Abstract

The application relates to the technical field of antennas, and particularly discloses a high-isolation dual-band MIMO antenna based on a mode cancellation method, which comprises a horizontal dielectric substrate and a vertical dielectric substrate placed on one side of the long side of the horizontal dielectric substrate, an antenna unit is printed on the middle part of the outer side of the vertical dielectric substrate; a first U-shaped slot, a second U-shaped slot and a third U-shaped slot are etched on the side of a metal floor close to the vertical dielectric substrate, the first U-shaped slot and the third U-shaped slot are symmetrically arranged relative to the second U-shaped slot; the sizes of the first U-shaped slot and the third U-shaped slot are the same, and the size of the first U-shaped slot is smaller than that of the second U-shaped slot; and a clearance is arranged on the side of the metal floor close to the vertical dielectric substrate. The application can realize low coupling in two working frequency bands, reduce the occupied space of the antenna, and realize the miniaturization of the antenna.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, and particularly relates to a high-isolation dual-band MIMO antenna based on a mode cancellation method. BACKGROUND

[0002] As one of the key technologies in 5G communication systems, multiple-input multiple-output (MIMO) technology can significantly improve the spectral efficiency and channel capacity of the system without increasing the spectrum resources and transmission power. However, the coupling problem between antenna elements in the MIMO antenna system becomes a key bottleneck restricting the performance of the system.

[0003] In the MIMO antenna system, the coupling between the antenna elements can cause problems such as degradation of matching performance, reduction of gain, and distortion of the directional pattern of the antenna, thereby affecting the communication performance of the entire system. In order to reduce the coupling between the antenna elements, researchers have proposed various decoupling methods, mainly including cancellation technology, blocking technology and self-decoupling technology. The cancellation technology cancels the coupling between the antenna elements by introducing an additional coupling path, such as the neutralization line technology and the loading decoupling unit; the blocking technology blocks the coupling between the antenna elements by introducing a band-stop structure (such as a defective ground structure and an electromagnetic bandgap structure); and the self-decoupling technology utilizes the internal decoupling characteristics of the mode, such as the orthogonality or cancellation characteristics of the antenna mode, to achieve decoupling without adding additional decoupling structures. Although the above decoupling methods have achieved certain results in single-frequency MIMO antennas, the complexity and implementation difficulty of the decoupling technology are still high in dual-frequency (such as N78 and N79 frequency bands) or even multi-frequency MIMO antennas, and further optimization and innovation are needed. SUMMARY

[0004] The purpose of the present application is to provide a high-isolation dual-band MIMO antenna based on a mode cancellation method to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a high-isolation dual-band MIMO antenna based on a mode cancellation method, which comprises a horizontal dielectric substrate and a vertical dielectric substrate, one side of the long side of the horizontal dielectric substrate is provided with the vertical dielectric substrate, the outer middle part of the vertical dielectric substrate is provided with an antenna element, and the lower surface of the horizontal dielectric substrate is printed with a metal ground plate.

[0006] A second U-shaped slot is etched in the middle part of one side of the vertical dielectric substrate close to the metal ground plate, a first U-shaped slot and a third U-shaped slot are etched on both sides of the second U-shaped slot respectively, and the first U-shaped slot and the third U-shaped slot are symmetrically arranged with respect to the second U-shaped slot; the size of the first U-shaped slot and the third U-shaped slot is the same, and the size of the first U-shaped slot and the third U-shaped slot is smaller than the size of the second U-shaped slot.

[0007] The metal floor is provided with a clearance zone near one side of the vertical dielectric substrate, and the length of the clearance zone is equal to the length of the side of the metal floor provided with the second U-shaped slot.

[0008] Preferably, the antenna unit comprises symmetrically arranged first and second U-shaped metal strips, and the U-shaped openings of the first and second U-shaped metal strips are arranged back to back; the ends of the first and second U-shaped metal strips are provided with metal vias, and the first and second U-shaped metal strips are connected with a microstrip feed line through the metal vias.

[0009] Preferably, the first and second U-shaped metal strips are composed of a first horizontal microstrip structure, a second vertical microstrip structure and a third horizontal microstrip structure connected in sequence, the length of the first horizontal microstrip structure is greater than the length of the third horizontal microstrip structure; and the metal via is arranged at the end of the third horizontal microstrip structure.

[0010] Preferably, the antenna unit is fed by a coaxial line.

[0011] Preferably, the first and third U-shaped slots are composed of a first vertical slot, a first horizontal slot and a second vertical slot connected in sequence; and the second U-shaped slot is composed of a third vertical slot, a second horizontal slot and a fourth vertical slot connected in sequence.

[0012] Preferably, the materials of the horizontal and vertical dielectric substrates are glass fiber epoxy resin, and the relative dielectric constant of the glass fiber epoxy resin is εr=4.4.

[0013] Preferably, the length of the horizontal dielectric substrate is 160 mm, the width is 80 mm, and the thickness is 2 mm.

[0014] The thickness of the vertical dielectric substrate is 1 mm, the height of the vertical dielectric substrate is 12 mm, and the distance between the long side of the horizontal dielectric substrate and the long side of the vertical dielectric substrate is 7 mm.

[0015] Preferably, the length of the microstrip feed line is 11 mm, and the width is 1 mm.

[0016] Preferably, the distance between the first and second U-shaped metal strips is 4 mm.

[0017] The length of the first vertical microstrip structure is 27.5 mm, and the height is 5 mm.

[0018] The length of the second horizontal microstrip structure is 2 mm, and the height is 2 mm.

[0019] The length of the third vertical microstrip structure is 19mm, and the height is 4mm.

[0020] Preferably, the width of the clearance is 4mm.

[0021] The outer edge length of the first vertical slit is 10.5mm, the inner edge length is 10mm, and the distance between the outer edge and the inner edge is 0.75mm.

[0022] The outer edge length of the first horizontal slit is 7.5mm, the inner edge length is 6mm, and the distance between the outer edge and the inner edge is 0.5mm.

[0023] The outer edge length of the third vertical slit is 14.5mm, the inner edge length is 14mm, and the distance between the outer edge and the inner edge is 0.5mm.

[0024] The outer edge length of the second horizontal slit is 7mm, the inner edge length is 6mm, and the distance between the outer edge and the inner edge is 0.5mm.

[0025] Compared with the prior art, the application has the following advantages and technical effects:

[0026] The high-isolation dual-band MIMO antenna based on the mode cancellation method provided by the application has a simple antenna structure, reduces the complexity of design and manufacturing, and can effectively work in the N77, N79 and Wi-Fi 6E / 7 UNII-1 and UNII-2A sub-frequency bands of Sub 6GHz. Based on the mode cancellation technology, the specific slot structure is etched, the common-mode and differential-mode impedance is adjusted, the conditions for mode cancellation are met, and low coupling is realized in the two working frequency bands (2.97GHz-4.22GHz and 4.56GHz-5.33GHz). In addition, the U-shaped slot etched by the application does not occupy additional decoupling space, and the miniaturization of the antenna is realized. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0028] Figure 1 The structure diagram of the high-isolation dual-band MIMO antenna based on the mode cancellation method of the application;

[0029] Figure 2A structure size schematic diagram of a high-isolation dual-band MIMO antenna based on a mode cancellation method in an embodiment of the present application;

[0030] Figure 3 An S parameter diagram of a high-isolation dual-band MIMO antenna based on a mode cancellation method in the present application;

[0031] Figure 4 A Smith chart comparison diagram of a common-mode reflection coefficient and a differential-mode reflection coefficient in a 2.97GHz-4.22GHz frequency band of a high-isolation dual-band MIMO antenna based on a mode cancellation method in the present application;

[0032] Figure 5 A Smith chart comparison diagram of a common-mode reflection coefficient and a differential-mode reflection coefficient in a 4.56GHz-5.33GHz frequency band of a high-isolation dual-band MIMO antenna based on a mode cancellation method in the present application;

[0033] In the figure: 1, horizontal dielectric substrate; 2, vertical dielectric substrate; 3, antenna unit; 4, metal ground plate; 5, clearance area; 6, first U-shaped slot; 61, first vertical slot; 62, first horizontal slot; 63, second vertical slot; 7, second U-shaped slot; 71, third vertical slot; 72, second horizontal slot; 73, fourth vertical slot; 8, third U-shaped slot; 9, first U-shaped metal strip; 91, first horizontal microstrip structure; 92, second vertical microstrip structure; 93, third horizontal microstrip structure; 10, second U-shaped metal strip; 11, metal via; 12, microstrip feed line. DETAILED DESCRIPTION

[0034] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The described embodiments are only part of the embodiments of the present application, not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] As Figure 1 shown, the present application provides a high-isolation dual-band MIMO antenna based on a mode cancellation method, comprising a horizontal dielectric substrate 1, one side of the long side of the horizontal dielectric substrate 1 is provided with a vertical dielectric substrate 2, the outer middle part of the vertical dielectric substrate 2 is provided with an antenna unit 3, and the lower surface of the horizontal dielectric substrate 1 is printed with a metal ground plate 4;

[0036] A second U-shaped slot 7 is etched in the middle of the side of the metal floor 4 closest to the vertical dielectric substrate 2. A first U-shaped slot 6 and a third U-shaped slot 8 are etched on both sides of the second U-shaped slot 7, respectively. The first U-shaped slot 6 and the third U-shaped slot 8 are symmetrically arranged with respect to the second U-shaped slot 7. The first U-shaped slot 6 and the third U-shaped slot 8 have the same size, but the size of the first U-shaped slot 6 and the third U-shaped slot 8 is smaller than the size of the second U-shaped slot 7.

[0037] A clearance area 5 is provided on the side of the metal floor 4 near the vertical dielectric substrate 2. The length of the clearance area 5 is equal to the side length of the side of the metal floor 4 where the second U-shaped gap 7 is provided.

[0038] In a further optimized design, antenna unit 3 includes a first U-shaped metal strip 9 and a second U-shaped metal strip 10 arranged symmetrically, with the U-shaped openings of the first U-shaped metal strip 9 and the second U-shaped metal strip 10 facing away from each other; metal vias 11 are provided at the ends of both the first U-shaped metal strip 9 and the second U-shaped metal strip 10, and microstrip feed lines 12 are connected to the first U-shaped metal strip 9 and the second U-shaped metal strip 10 through the metal vias 11.

[0039] In a further optimized design, the first U-shaped metal strip 9 and the second U-shaped metal strip 10 are both composed of a first horizontal microstrip structure 91, a second vertical microstrip structure 92 and a third horizontal microstrip structure 93 connected in sequence. The length of the first horizontal microstrip structure 91 is greater than the length of the third horizontal microstrip structure 93. The metal via 11 is located at the end of the third horizontal microstrip structure 93.

[0040] To further optimize the design, antenna element 3 is fed using a coaxial cable.

[0041] Further optimization of the scheme: the first U-shaped gap 6 and the third U-shaped gap 8 are both composed of the first vertical gap 61, the first horizontal gap 62 and the second vertical gap 63 connected in sequence; the second U-shaped gap 7 is composed of the third vertical gap 71, the second horizontal gap 72 and the fourth vertical gap 73 connected in sequence.

[0042] Example

[0043] like Figure 2 As shown, the horizontal dielectric substrate 1 and the vertical dielectric substrate 2 are made of glass fiber epoxy resin, and the relative permittivity of the glass fiber epoxy resin is εr=4.4.

[0044] Further optimization of the scheme: the length Ls of the horizontal dielectric substrate 1 is 160mm, the width Ws is 80mm, and the thickness Hs is 2mm;

[0045] The thickness ts of the vertical dielectric substrate 2 is 1mm, the distance t1 between the long side of the horizontal dielectric substrate 1 and the long side of the vertical dielectric substrate 2 is 7mm, and the height Wss of the vertical dielectric substrate 2 is 12mm.

[0046] In a further optimization scheme, the length g1 of the microstrip feed line 12 is 11mm, and the width tf is 1mm.

[0047] In a further optimization scheme, the distance dd between the first U-shaped metal strip 9 and the second U-shaped metal strip 10 is 4mm.

[0048] The length Lp1 of the first horizontal microstrip structure 91 is 27.5mm, and the height Wp1 is 5mm.

[0049] The length Dis of the second vertical microstrip structure 92 is 2mm, and the height Wp2 is 2mm.

[0050] The length Lp2 of the third horizontal microstrip structure 93 is 19mm, and the height Wp3 is 4mm.

[0051] In a further optimization scheme, the width C1 of the clearance 5 is 4mm.

[0052] The outer edge length ba1 of the first vertical slot 61 is 10.5mm, the inner edge length ba is 10mm, and the distance pp between the outer edge and the inner edge is 0.75mm.

[0053] The outer edge length aa1 of the first horizontal slot 62 is 7.5mm, the inner edge length aa is 6mm, and the distance pp1 between the outer edge and the inner edge is 0.5mm.

[0054] The outer edge length ba2 of the third vertical slot 71 is 14.5mm, the inner edge length ba3 is 14mm, and the distance qq between the outer edge and the inner edge is 0.5mm.

[0055] The outer edge length aa2 of the second horizontal slot 72 is 7mm, the inner edge length aa3 is 6mm, and the distance qq1 between the outer edge and the inner edge is 0.5mm.

[0056] The high-isolation dual-band MIMO antenna based on the mode cancellation method provided by the application has the antenna units 3 placed back to back, and by adjusting the parameters of the first horizontal microstrip structure 91 and the third horizontal microstrip structure 93, the antenna can work in two frequency bands, i.e. 2.97GHz-4.22GHz and 4.56GHz-5.33GHz, and can be well applied to a 5G communication system, thereby improving the communication performance and reliability of the MIMO system. Figure 3The S parameter diagram of the antenna is shown, and it can be seen from the diagram that the antenna covers two frequency bands, and the reflection coefficient is less than -6dB in the whole working frequency band, indicating that the antenna realizes good impedance matching in the two frequency bands. At the same time, according to the mode cancellation theory, when the difference between the common-mode reflection coefficient (Scc 11 -Sdd 11 |<0.632 conditions, i.e. the decoupling between the ports can be realized. This means that when the distance between the common-mode and differential-mode reflection coefficients on the Smith chart is small enough, the coupling between the antenna ports will be significantly suppressed, thereby realizing lower coupling between the antenna units 3. By etching the first U-shaped slot 6 and the third U-shaped slot 8 on the side of the metal ground plate 4 close to the vertical dielectric substrate 2, the distance between the common-mode reflection coefficient and the differential-mode reflection coefficient of the antenna in the 2.97GHz-4.22GHz frequency band is effectively adjusted, and high isolation between the antenna units in this frequency band is realized; at the same time, the introduction of the first U-shaped slot 6 and the third U-shaped slot 8 moves the common-mode reflection coefficient of the 4.56GHz-5.33GHz frequency band to the left upper inductive region, but the coupling between the antenna units is still relatively large. On the basis of the above-mentioned antenna structure, the second U-shaped slot 7 is etched in the middle of the side of the metal ground plate 4 close to the vertical dielectric substrate 2, which reduces the distance between the common-mode and differential-mode reflection coefficients of the antenna in the 4.56-5.33GHz frequency band, and further effectively reduces the coupling between the antenna units 3.

[0057] Figure 4 and Figure 5 The Smith contrast diagrams of the common-mode reflection coefficient and the differential-mode reflection coefficient in the 2.97GHz-4.22GHz frequency band and the 4.56GHz-5.33GHz frequency band are shown respectively. It can be seen from the diagrams that the distance between the common-mode reflection coefficient and the differential-mode reflection coefficient in the two frequency bands is less than 0.632, which meets the decoupling condition of the mode cancellation theory. Therefore, the present application shows good isolation characteristics in the two key frequency bands.

[0058] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application.

Claims

1. A high-isolation dual-band MIMO antenna based on mode cancellation method, characterized in that, It includes a horizontal dielectric substrate (1) and a vertical dielectric substrate (2). The vertical dielectric substrate (2) is placed on one side of the long side of the horizontal dielectric substrate (1). An antenna unit (3) is printed on the middle of the outer side of the vertical dielectric substrate (2). A metal ground plane (4) is printed on the lower surface of the horizontal dielectric substrate (1). The metal floor (4) has a second U-shaped slot (7) etched in the middle of one side near the vertical dielectric substrate (2). A first U-shaped slot (6) and a third U-shaped slot (8) are etched on both sides of the second U-shaped slot (7). The first U-shaped slot (6) and the third U-shaped slot (8) are symmetrically arranged with respect to the second U-shaped slot (7). The first U-shaped slot (6) and the third U-shaped slot (8) have the same size, and the size of the first U-shaped slot (6) and the third U-shaped slot (8) is smaller than the size of the second U-shaped slot (7). The metal floor (4) has a clearance area (5) on the side near the vertical dielectric substrate (2), and the length of the clearance area (5) is equal to the side length of the side of the metal floor (4) where the second U-shaped gap (7) is provided.

2. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 1, characterized in that, The antenna unit (3) includes a first U-shaped metal strip (9) and a second U-shaped metal strip (10) placed symmetrically, with the U-shaped opening of the first U-shaped metal strip (9) and the U-shaped opening of the second U-shaped metal strip (10) facing away from each other; both the first U-shaped metal strip (9) and the second U-shaped metal strip (10) are provided with metal vias (11), and the first U-shaped metal strip (9) and the second U-shaped metal strip (10) are connected to a microstrip feed line (12) through the metal vias (11).

3. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 2, characterized in that, The first U-shaped metal strip (9) and the second U-shaped metal strip (10) are both composed of a first horizontal microstrip structure (91), a second vertical microstrip structure (92) and a third horizontal microstrip structure (93) connected in sequence. The length of the first horizontal microstrip structure (91) is greater than the length of the third horizontal microstrip structure (93). The metal via (11) is located at the end of the third horizontal microstrip structure (93).

4. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 1, characterized in that, The antenna unit (3) is fed by a coaxial line.

5. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 1, characterized in that, The first U-shaped gap (6) and the third U-shaped gap (8) are both composed of a first vertical gap (61), a first horizontal gap (62) and a second vertical gap (63) connected in sequence; the second U-shaped gap (7) is composed of a third vertical gap (71), a second horizontal gap (72) and a fourth vertical gap (73) connected in sequence.

6. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 1, characterized in that, The horizontal dielectric substrate (1) and the vertical dielectric substrate (2) are made of glass fiber epoxy resin, and the relative permittivity of the glass fiber epoxy resin is εr=4.

4.

7. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 6, characterized in that, The horizontal dielectric substrate (1) has a length of 160 mm, a width of 80 mm, and a thickness of 2 mm; The thickness of the vertical dielectric substrate (2) is 1 mm, the height of the vertical dielectric substrate (2) is 12 mm, and the distance between the long side of the horizontal dielectric substrate (1) and the long side of the vertical dielectric substrate (2) is 7 mm.

8. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 3, characterized in that, The microstrip feed line (12) has a length of 11 mm and a width of 1 mm.

9. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 3, characterized in that, The distance between the first U-shaped metal strip (9) and the second U-shaped metal strip (10) is 4 mm; The first horizontal microstrip structure (91) has a length of 27.5 mm and a height of 5 mm; The second vertical microstrip structure (92) has a length of 2 mm and a height of 2 mm; The third horizontal microstrip structure (93) has a length of 19 mm and a height of 4 mm.

10. The high-isolation dual-band MIMO antenna based on mode cancellation method according to claim 5, characterized in that, The width of the clearance area (5) is 4 mm; The outer edge length of the first vertical slit (61) is 10.5 mm, the inner edge length is 10 mm, and the distance between the outer edge and the inner edge is 0.75 mm; The outer edge length of the first horizontal gap (62) is 7.5 mm, the inner edge length is 6 mm, and the distance between the outer edge and the inner edge is 0.5 mm; The outer edge length of the third vertical slit (71) is 14.5 mm, the inner edge length is 14 mm, and the distance between the outer edge and the inner edge is 0.5 mm; The second horizontal gap (72) has an outer edge length of 7mm, an inner edge length of 6mm, and a distance of 0.5mm between the outer and inner edges.

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