Dual-band self-decoupling MIMO antenna based on mode cancellation method

Abstract

The invention relates to the technical field of antennas, and particularly discloses a dual-band self-decoupling MIMO antenna based on a mode cancellation method, which comprises a horizontal dielectric substrate, and a first vertical dielectric substrate and a second vertical dielectric substrate which are arranged on the two sides of the horizontal dielectric substrate, an antenna unit is arranged in the middle of the outer side of the first vertical dielectric substrate, and the second vertical dielectric substrate is arranged in the middle of the outer side of the second vertical dielectric substrate. A metal floor is printed on the lower surface of the horizontal dielectric substrate; a first U-shaped gap, a second U-shaped gap and a third U-shaped gap are etched in the middle of one side, close to the first vertical dielectric substrate, of the metal floor, and the first U-shaped gap and the third U-shaped gap are symmetrically arranged relative to the second U-shaped gap; the first U-shaped gap and the third U-shaped gap are the same in size, and the size of the first U-shaped gap is smaller than that of the second U-shaped gap; the two sides, close to the first vertical dielectric substrate and the second vertical dielectric substrate, of the metal floor are provided with clearance areas. According to the invention, low coupling can be realized in two working frequency bands, the occupied space of the antenna is reduced, and the miniaturization of the antenna is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and particularly to a dual-band self-decoupling MIMO antenna based on a mode cancellation method. Background Art

[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 spectral resources and transmission power. However, the coupling problem between antenna elements in the MIMO antenna system has become a key bottleneck restricting the performance of the system.

[0003] In the MIMO antenna system, the coupling between antenna elements will lead to problems such as a decrease in the matching performance of the antenna, a reduction in gain, and a distortion of the radiation pattern, thus affecting the communication performance of the entire system. To reduce the coupling between antenna elements, researchers have proposed a variety of decoupling methods, mainly including cancellation techniques, blocking techniques, and self-decoupling techniques. The cancellation technique cancels the coupling between antenna elements by introducing an additional coupling path, such as the neutralization line technique and the loaded decoupling unit; the blocking technique blocks the coupling between antenna elements by introducing a band-stop structure (such as a defected ground structure and an electromagnetic bandgap structure); the self-decoupling technique utilizes the decoupling characteristics within 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-band MIMO antennas, in dual-band (such as N78 and N79 bands) or even multi-band MIMO antennas, the complexity and implementation difficulty of the decoupling technology are still relatively high, and further optimization and innovation are urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a dual-band self-decoupling MIMO antenna based on a mode cancellation method to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above purpose, the present invention provides a dual-band self-decoupling MIMO antenna based on a mode cancellation method, which includes a horizontal dielectric substrate. On the opposite sides of the horizontal dielectric substrate, a first vertical dielectric substrate and a second vertical dielectric substrate are respectively arranged. In the middle of the outer side of the first vertical dielectric substrate, an antenna element is arranged, and a metal floor is printed on the lower surface of the horizontal dielectric substrate.

[0006] On one side of the metal floor close to the first vertical dielectric substrate, a second U-shaped slot is etched in the middle. On both sides of the second U-shaped slot, a first U-shaped slot and a third U-shaped slot are respectively etched. The first U-shaped slot and the third U-shaped slot are symmetrically arranged with respect to the second U-shaped slot; the first U-shaped slot and the third U-shaped slot have the same size, 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] On both sides of the metal floor close to the first vertical dielectric substrate and the second vertical dielectric substrate, clearance areas are provided. The length of the clearance area is equal to the side length of the side of the metal floor where the second U-shaped slot is provided.

[0008] Preferably, the antenna unit includes a first U-shaped metal strip and a second U-shaped metal strip that are symmetrically arranged, and the U-shaped openings of the first U-shaped metal strip and the U-shaped openings of the second U-shaped metal strip face away from each other; metal vias are provided at the ends of the first U-shaped metal strip and the second U-shaped metal strip, and the first U-shaped metal strip and the second U-shaped metal strip are connected to a microstrip line through the metal vias.

[0009] Preferably, both the first U-shaped metal strip and the second U-shaped metal strip 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; the metal via is provided at the end of the third horizontal microstrip structure.

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

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

[0012] Preferably, the materials of the horizontal dielectric substrate, the first vertical dielectric substrate, and the second vertical dielectric substrate 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 first vertical dielectric substrate and the second vertical dielectric substrate is 1 mm, the height of the first vertical dielectric substrate and the second vertical dielectric substrate is 12 mm, and the distance between the horizontal dielectric substrate and the first vertical dielectric substrate is 7 mm.

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

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

[0017] The length of the first horizontal microstrip structure is 27.5 mm and the height is 5 mm;

[0018] The length of the second vertical microstrip structure is 2 mm and the height is 2 mm;

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

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

[0021] The outer side length of the first horizontal slit one is 10.5 mm, the inner side length is 10 mm, and the distance between the outer side and the inner side is 0.75 mm;

[0022] The outer side length of the second vertical slit one is 7.5 mm, the inner side length is 6 mm, and the distance between the outer side and the inner side is 0.5 mm;

[0023] The outer side length of the first horizontal slit two is 14.5 mm, the inner side length is 14 mm, and the distance between the outer side and the inner side is 0.5 mm;

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

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

[0026] The dual-band self-decoupling MIMO antenna based on the mode cancellation method provided by the present invention has a simple antenna structure, reduces the complexity of design and manufacturing, and can effectively operate in the N78 and N79 frequency bands of Sub 6 GHz. In addition, based on the mode cancellation technology, the present invention can achieve low coupling in two operating frequency bands without adding any additional decoupling structures, thereby reducing the occupied space of the antenna and realizing the miniaturization of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 Schematic structural diagram of the dual-band self-decoupling MIMO antenna based on the mode cancellation method of the present invention;

[0029] Figure 2 Schematic diagram of the structural dimensions of the dual-band self-decoupling MIMO antenna based on the mode cancellation method in the embodiment of the present invention;

[0030] Figure 3 S-parameter diagram of the dual-band self-decoupling MIMO antenna based on the mode cancellation method of the present invention;

[0031] Figure 4 Smith comparison diagram of the common-mode reflection coefficient and differential-mode reflection coefficient of the dual-band self-decoupling MIMO antenna based on the mode cancellation method of the present invention at the 3.5 GHz frequency band;

[0032] Figure 5 Smith comparison diagram of the common-mode reflection coefficient and differential-mode reflection coefficient of the dual-band self-decoupling MIMO antenna based on the mode cancellation method of the present invention at the 4.9 GHz frequency band;

[0033] In the figure: 1, horizontal dielectric substrate; 2, first vertical dielectric substrate; 3, second vertical dielectric substrate; 4, antenna element; 5, metal floor; 6, first U-shaped slot; 61, first horizontal slot one; 62, second vertical slot one; 63, third horizontal slot one; 7, second U-shaped slot; 71, first horizontal slot two; 72, second vertical slot two; 73, third horizontal slot two; 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 line; 13, clearance area. Detailed implementation manners

[0034] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0035] As Figure 1 shown, the present invention provides a dual-band self-decoupling MIMO antenna based on the mode cancellation method, which includes a horizontal dielectric substrate 1. On the opposite sides of the horizontal dielectric substrate 1, a first vertical dielectric substrate 2 and a second vertical dielectric substrate 3 are respectively arranged. In the middle of the outer side of the first vertical dielectric substrate 2, an antenna element 4 is arranged. On the lower surface of the horizontal dielectric substrate 1, a metal floor 5 is printed;

[0036] On one side of the metal floor 5 close to the middle of the first vertical dielectric substrate 2, a second U-shaped slot 7 is etched. On both sides of the second U-shaped slot 7, a first U-shaped slot 6 and a third U-shaped slot 8 are respectively etched. 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 that of the second U-shaped slot 7.

[0037] On both sides of the metal floor 5 close to the first vertical dielectric substrate 2 and the second vertical dielectric substrate 3, clearance areas 13 are provided. The length of the clearance area 13 is equal to the side length of the side of the metal floor 5 where the second U-shaped slot 7 is provided.

[0038] In a further optimized solution, the antenna unit 4 includes a first U-shaped metal strip 9 and a second U-shaped metal strip 10 which are symmetrically arranged, and the U-shaped openings of the first U-shaped metal strip 9 and the second U-shaped metal strip 10 face away from each other; metal vias 11 are provided at the ends of the first U-shaped metal strip 9 and the second U-shaped metal strip 10, and the first U-shaped metal strip 9 and the second U-shaped metal strip 10 are connected to a microstrip line 12 through the metal vias 11.

[0039] In a further optimized solution, both the first U-shaped metal strip 9 and the second U-shaped metal strip 10 are composed of a first horizontal microstrip structure 91, a second vertical microstrip structure 92 and a third horizontal microstrip structure 93 connected in sequence, and 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 provided at the end of the third horizontal microstrip structure 93.

[0040] In a further optimized solution, the antenna unit 4 is fed by a coaxial cable.

[0041] In a further optimized solution, both the first U-shaped slot 6 and the third U-shaped slot 8 are composed of a first horizontal slot one 61, a second vertical slot one 62 and a third horizontal slot one 63 connected in sequence; the second U-shaped slot 7 is composed of a first horizontal slot two 71, a second vertical slot two 72 and a third horizontal slot two 73 connected in sequence.

[0042] Embodiment

[0043] As Figure 2 shown, the materials of the horizontal dielectric substrate 1, the first vertical dielectric substrate 2 and the second vertical dielectric substrate 3 are glass fiber epoxy resin, and the relative dielectric constant of the glass fiber epoxy resin is εr = 4.4.

[0044] In a further optimized solution, the length Ls of the horizontal dielectric substrate 1 is 160 mm, the width Ws is 80 mm, and the thickness Hs is 2 mm;

[0045] The thickness ts of the first vertical dielectric substrate 2 and the second vertical dielectric substrate 3 is 1 mm, the distance t1 between the horizontal dielectric substrate 1 and the first vertical dielectric substrate 2 is 7 mm, and the heights Wss of the first vertical dielectric substrate 2 and the second vertical dielectric substrate 3 are both 12 mm.

[0046] In a further optimized solution, the length g1 of the microstrip line 12 is 11 mm, and the diameter tf is 1 mm.

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

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

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

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

[0051] In a further optimized solution, the width C1 of the clearance area 13 is 4 mm;

[0052] The outer length ba1 of the first horizontal slit 61 is 10.5 mm, the inner length ba is 10 mm, and the distance pp between the outer side and the inner side is 0.75 mm;

[0053] The outer length aa1 of the second vertical slit 62 is 7.5 mm, the inner length aa is 6 mm, and the distance pp1 between the outer side and the inner side is 0.5 mm;

[0054] The outer length ba2 of the first horizontal slit 71 is 14.5 mm, the inner length ba3 is 14 mm, and the distance qq between the outer side and the inner side is 0.5 mm;

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

[0056] For the dual-band self-decoupling MIMO antenna based on the mode cancellation method provided by the present invention, the antenna elements 4 are placed back to back. By adjusting the parameters of the first horizontal microstrip structure 91 and the third horizontal microstrip structure 93, the antenna can operate in two frequency bands, namely 3.5 GHz (3.3 GHz - 3.8 GHz) and 4.9 GHz (4.5 GHz - 5 GHz), and can be well applied to the 5G communication system, thereby improving the communication performance and reliability of the MIMO system. Figure 3The S-parameter diagram of the antenna is shown. It can be seen from the diagram that the antenna covers two frequency bands, and the reflection coefficient is less than -6 dB within the entire operating frequency band, indicating that the antenna achieves 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 (Scc11) and the differential-mode reflection coefficient (Sdd11) of a symmetric reciprocal two-port antenna system satisfies the condition of the formula |Scc11 - Sdd11| < 0.632, self-decoupling between ports can be achieved. 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 achieving lower coupling between antenna elements 4. By etching a U-shaped groove on the metal floor 5, the common-mode reflection coefficient and the differential-mode reflection coefficient of the antenna can be effectively adjusted to make their difference as small as possible, thereby effectively reducing the coupling between antenna elements 4. Figure 4 and Figure 5 respectively give the Smith comparison diagrams of the common-mode reflection coefficient and the differential-mode reflection coefficient in the 3.5 GHz (3.3 GHz - 3.8 GHz) frequency band and the 4.9 GHz (4.5 GHz - 5 GHz) frequency band. It can be seen from the diagram that within the two frequency bands, the distance between the common-mode reflection coefficient and the differential-mode reflection coefficient can basically meet the requirement of being less than 0.632, satisfying the decoupling condition of the mode cancellation theory. Therefore, through the analysis of the S-parameters and combined with the mode cancellation theory, the present invention exhibits good self-decoupling characteristics in the two key frequency bands.

[0057] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A dual-band self-decoupled MIMO antenna based on a pattern cancellation method, characterized in that It includes a horizontal dielectric substrate (1), with a first vertical dielectric substrate (2) and a second vertical dielectric substrate (3) respectively arranged on two opposite sides of the horizontal dielectric substrate (1). An antenna unit (4) is arranged in the middle on the outer side of the first vertical dielectric substrate (2), and a metal floor (5) is printed on the lower surface of the horizontal dielectric substrate (1). In the middle on one side of the metal floor (5) close to the first vertical dielectric substrate (2), a second U-shaped slot (7) is etched. On both sides of the second U-shaped slot (7), a first U-shaped slot (6) and a third U-shaped slot (8) are respectively etched. 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 that of the second U-shaped slot (7). Clearance areas (13) are arranged on both sides of the metal floor (5) close to the first vertical dielectric substrate (2) and the second vertical dielectric substrate (3), and the length of the clearance area (13) is equal to the side length of the side of the metal floor (5) where the second U-shaped slot (7) is arranged.

2. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 1, wherein The antenna unit (4) includes a first U-shaped metal strip (9) and a second U-shaped metal strip (10) which are symmetrically arranged, and the U-shaped openings of the first U-shaped metal strip (9) and the second U-shaped metal strip (10) face away from each other; metal vias (11) are arranged at the ends of the first U-shaped metal strip (9) and the second U-shaped metal strip (10), and the first U-shaped metal strip (9) and the second U-shaped metal strip (10) are connected to a microstrip line (12) through the metal vias (11).

3. The dual-band self-decoupling MIMO antenna based on the pattern cancellation method according to claim 2, wherein Both the first U-shaped metal strip (9) and the second U-shaped metal strip (10) are 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 arranged at the end of the third horizontal microstrip structure (93).

4. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 1, characterized in that The antenna unit (4) is fed by a coaxial cable.

5. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 1, characterized in that, Both the first U-shaped slot (6) and the third U-shaped slot (8) are composed of a first horizontal slot one (61), a second vertical slot one (62), and a third horizontal slot one (63) connected in sequence; the second U-shaped slot (7) is composed of a first horizontal slot two (71), a second vertical slot two (72), and a third horizontal slot two (73) connected in sequence.

6. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 1, wherein The materials of the horizontal dielectric substrate (1), the first vertical dielectric substrate (2), and the second vertical dielectric substrate (3) are glass fiber epoxy resin, and the relative dielectric constant of the glass fiber epoxy resin is εr = 4.

4.

7. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 6, characterized in that, The length of the horizontal dielectric substrate (1) is 160 mm, the width is 80 mm, and the thickness is 2 mm. The thickness of the first vertical dielectric substrate (2) and the second vertical dielectric substrate (3) is 1 mm, the height of the first vertical dielectric substrate (2) and the second vertical dielectric substrate (3) is 12 mm, and the distance between the horizontal dielectric substrate (1) and the first vertical dielectric substrate (2) is 7 mm.

8. The dual-band self-decoupled MIMO antenna based on the pattern cancellation method according to claim 3, characterized in that The length of the microstrip line (12) is 11 mm and the diameter is 1 mm.

9. The dual-band self-decoupling MIMO antenna based on the pattern 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 length of the first horizontal microstrip structure (91) is 27.5 mm and the height is 5 mm; The length of the second vertical microstrip structure (92) is 2 mm and the height is 2 mm; The length of the third horizontal microstrip structure (93) is 19 mm and the height is 4 mm.

10. The dual-band self-decoupling MIMO antenna based on the pattern cancellation method according to claim 5, characterized in that, The width of the clearance area (13) is 4 mm; The outer side length of the first horizontal slit one (61) is 10.5 mm, the inner side length is 10 mm, and the distance between the outer side and the inner side is 0.75 mm; The outer side length of the second vertical slit one (62) is 7.5 mm, the inner side length is 6 mm, and the distance between the outer side and the inner side is 0.5 mm; The outer side length of the first horizontal slit two (71) is 14.5 mm, the inner side length is 14 mm, and the distance between the outer side and the inner side is 0.5 mm; The outer side length of the second vertical slit two (72) is 7 mm, the inner side length is 6 mm, and the distance between the outer side and the inner side is 0.5 mm.

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