Double-frequency common-caliber base station antenna array

Abstract

The invention provides a double-frequency common-caliber base station antenna array which comprises a high-frequency array fixed on a metal reflecting plate and a low-frequency antenna unit located in the middle of the high-frequency array. A low-frequency radiation unit in the low-frequency antenna unit is composed of two groups of mutually crossed low-frequency dipole arms, each low-frequency dipole arm is composed of two quadrilateral or hexagonal metal rings, and the positions of four notches formed in the metal rings are inwards connected with composite decoupling structures respectively; and the low-frequency radiation unit is arranged above the high-frequency array and partially coincides with the projection of the high-frequency array on the reflecting plate. The composite decoupling structure can induce high-frequency induction current on the low-frequency dipole arms to achieve reverse offset in a wide frequency band, interference of the low-frequency radiation unit on high-frequency electromagnetic waves is reduced, a good high-frequency directional diagram shape preserving effect is achieved, the low-frequency dipole arms are printed on the dielectric substrate, the structure is simple, and the antenna is convenient to manufacture. And meanwhile, the current path of the low-frequency radiation unit is prolonged by the composite decoupling structure, and miniaturization is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications and relates to a dual-frequency co-aperture base station antenna array. Background Art

[0002] In mobile communication systems, 5G will coexist with 2G, 3G, and 4G for a long time. Due to the increase in operating frequency bands and limited deployment space, antennas of multiple frequency bands in the base station platform need to be arranged with a common aperture in a limited space. Multi-frequency common aperture base station antennas can achieve signal coverage of multiple network formats without increasing the space occupied by base station antenna equipment, greatly alleviating the shortage of base station site resources, thereby reducing the operating costs of operators.

[0003] However, in the co-aperture layout, the distance between antenna units is very close, resulting in enhanced coupling interference between antennas in different frequency bands. Among them, the low-frequency antennas distributed above the high-frequency antennas block the high-frequency electromagnetic waves and produce secondary radiation, causing distortion of the high-frequency antenna pattern. Therefore, designing low-frequency antennas that are "electromagnetically transparent" to high-frequency electromagnetic waves is an important method to restore the high-frequency pattern in the co-aperture base station antenna array.

[0004] However, the electromagnetic transparent bandwidth of the low-frequency antenna in the existing dual-frequency co-aperture base station antenna is relatively narrow, and it is impossible to ensure that the high-frequency antenna meets the gain and half-power beamwidth requirements required for the normal operation of the base station antenna. This will limit the working bandwidth of the high-frequency antenna in the co-aperture base station antenna array, and the structure is complex, resulting in difficulties in debugging and processing the antenna. For example, the patent document entitled "A Co-aperture Base Station Antenna Array" with the authorization announcement number CN115313065B discloses a co-aperture base station antenna array. The invention includes a low-frequency dual-polarization antenna, a high-frequency dual-polarization antenna and an antenna array metal plate, wherein the low-frequency dual-polarization antenna is fixed to the antenna array metal plate by a nylon column; the high-frequency dual-polarization antenna is arranged on both sides of the low-frequency dual-polarization antenna and fixed to the antenna array metal plate by a nylon column, and half of the area of ​​the high-frequency dual-polarization antenna is located directly below the low-frequency dual-polarization antenna. This invention can suppress the induced current caused by the excitation of the high-frequency antenna through the spiral choke in the antenna, reduce the impact on the electromagnetic waves radiated by the high-frequency antenna, and achieve high-frequency electromagnetic transparency. The width of the two feeding microstrip lines on the front side of the low-frequency antenna's feeding PCB and the gap in the metal ground on the back side of the PCB can be flexibly adjusted to enable the antenna to obtain good impedance matching. However, its defect is that the high-frequency antenna in the array has a narrow operating bandwidth due to the deterioration of performance such as radiation pattern and gain, and only operates at 1.71-1.83GHz, and its spiral choke decoupling structure consists of multiple metal strips and metal through-holes, and the structure is relatively complex. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and propose a dual-frequency co-aperture base station antenna array, aiming to broaden the working bandwidth of the base station antenna array and simplify the structure.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a metal reflector 1 and a high-frequency array consisting of multiple dual-polarized high-frequency antenna units 2 fixed thereon, and a dual-polarized low-frequency antenna unit 3 located in the middle of the high-frequency array; the high-frequency array is composed of 2*2 high-frequency antenna units 2; the low-frequency antenna unit 3 includes a low-frequency radiation unit consisting of a square first dielectric substrate 31 and two groups of intersecting low-frequency dipole arms 32 printed on its upper surface, and two baluns 34; the low-frequency dipole arm 32 is composed of two quadrilateral or hexagonal metal rings, each of which is provided with four notches, and each of the notches is connected inwardly with a composite decoupling structure 35; the low-frequency radiation unit is arranged above the high-frequency array, and its projection on the reflector is at least partially overlapped with the projection of the high-frequency array on the reflector, and the two baluns 34 are arranged longitudinally, with their top ends fixed to the low-frequency radiation unit and their bottom ends fixed to the metal reflector 1.

[0007] As an optimization, the two baluns 34 are fixed on the metal reflector 1 via a mounting base plate 33 .

[0008] As an optimization, the high-frequency antenna unit 2 includes a square second dielectric substrate 21 and a square third dielectric substrate 23 fixed on top thereof by a nylon column 22, and two feeding coaxial lines 24; the lower surface of the second dielectric substrate 21 is printed with a first metal base plate 25, on which a rectangular notch is etched, and the upper surface of the second dielectric substrate 21 is located above the rectangular notch etched on the first metal base plate 25 and is printed with a metal patch 26; two groups of high-frequency dipole arms 27 that cross each other are printed on the two diagonal lines on the lower surface of the third dielectric substrate 23, each group of high-frequency dipole arms is composed of two octagonal metal rings, and a coupling feeding structure 28 is printed on the upper surface of the third dielectric substrate 23; the outer conductors at the lower ends of the two feeding coaxial lines 24 are connected to the metal patch 26, the outer conductors at the upper ends of the two feeding coaxial lines 24 are connected to the high-frequency dipole arms 27, and the inner conductors are connected to the coupling feeding structure 28.

[0009] As an optimization, the low-frequency dipole arm 32 is composed of two hexagonal metal rings, each of which is located on the diagonal of the first dielectric substrate 31, with one set of diagonals being 90°, and the other two sets of diagonals being 135°; the composite decoupling structure 35 is a Y-shaped composite structure, connected to the notch positions on the two adjacent sides of the hexagonal metal ring with a diagonal angle of 90°.

[0010] As an optimization, the two upper arms of the Y-shaped composite structure are composed of two U-shaped metal strips connected on one side, and the other side of the two U-shaped metal strips forms the lower arm of the Y-shaped composite structure, which is connected to the notch position of the adjacent side of the hexagonal metal ring with a diagonal angle of 90°.

[0011] As an optimization, the low-frequency dipole arm 32 is composed of two regular quadrilateral metal rings; the four composite decoupling structures 35 are all T-shaped composite structures, which are respectively connected to the four sides of the regular quadrilateral metal ring.

[0012] As an optimization, the T-shaped composite structure has a transverse arm composed of two U-shaped metal strips connected on one side, and the other sides of the two U-shaped metal strips are each connected to a short metal branch to form a longitudinal arm of the T-shaped composite structure, which is connected to the notch on the edge of the regular quadrilateral metal ring.

[0013] As an optimization, the two baluns 34 have the same structure, both including a fourth dielectric substrate 341 and a metal microstrip line 342 printed on one surface thereof and a second metal base plate 343 etched with a rectangular gap in the middle of the other surface, wherein the two second metal base plates 343 on the two baluns are respectively connected to a group of low-frequency dipole arms 32, and the impedance matching of the low-frequency antenna unit 3 is adjusted by adjusting the size of the microstrip line and the rectangular gap.

[0014] As an optimization, the first dielectric substrate 31 is provided with a mounting hole for mounting the fourth dielectric substrate 341 .

[0015] As an optimization, the intersection of the two groups of intersecting low-frequency dipole arms 32 and the center of the high-frequency array are both located in the center normal direction of the first dielectric substrate 31 .

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The low-frequency dipole arm of the present invention is composed of two quadrilateral or hexagonal metal rings, each of which is provided with four notches, and each notch is connected inwardly with a composite decoupling structure. The composite decoupling structure can induce the high-frequency induced current on the low-frequency dipole arm to achieve reverse cancellation within a wider frequency band, thereby reducing the interference of the low-frequency radiation unit to the high-frequency electromagnetic wave under the common aperture layout, and has a better high-frequency directional pattern conformal effect. Compared with the prior art, it effectively broadens the working bandwidth of the base station antenna array.

[0018] 2. The low-frequency dipole arms and the composite decoupling structure contained in the two sets of intersecting low-frequency dipole arms in the present invention are printed on the same dielectric substrate, which has a simple structure and is convenient for debugging and processing of the antenna. At the same time, the composite decoupling structure adopts a Y-shaped or T-shaped composite structure, which extends the current path of the low-frequency radiation unit and realizes miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of Example 1 of the present invention.

[0020] Figure 2 It is a schematic structural diagram of a high-frequency antenna unit according to an embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the structure of the low-frequency antenna unit of embodiment 1 of the present invention.

[0022] Figure 4 It is a schematic diagram of the structure of the low-frequency radiation unit of Example 1 of the present invention.

[0023] Figure 5 It is a schematic diagram of the structure of the low-frequency radiation unit of Example 2 of the present invention.

[0024] Figure 6 It is an S parameter diagram of the low-frequency antenna unit and the high-frequency antenna unit of Example 1 of the present invention.

[0025] Figure 7 It is a comparison diagram of the gain and horizontal plane radiation pattern of Example 1 of the present invention and a single high-frequency antenna array. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] Embodiment 1: The low-frequency dipole arm in this embodiment is composed of two hexagonal metal rings, and the composite decoupling structure is Y-shaped.

[0028] Reference Figure 1 The present invention comprises a metal reflector 1 and a high frequency array consisting of a plurality of dual-polarized high frequency antenna units 2 fixed thereon, and a dual-polarized low frequency antenna unit 3 located in the middle of the high frequency array. The high frequency array consists of 2*2 high frequency antenna units 2. The intersection of the two groups of intersecting low frequency dipole arms 32 and the center of the high frequency array are both located in the center normal direction of the first dielectric substrate 31.

[0029] Among them, the metal reflector 1 adopts a square aluminum metal plate, and the vertical distances between the low-frequency dipole arm 32 and the high-frequency dipole arm 27 and the metal reflector 1 are respectively close to one-quarter wavelength of the center frequency of the corresponding frequency band, thereby realizing directional radiation of the low-frequency antenna unit 3 and the high-frequency antenna unit 4.

[0030] Reference Figure 2 The high frequency antenna unit 2 includes a second dielectric substrate 21 and a third dielectric substrate 23 fixed thereon by a nylon column 22 , and two feeding coaxial lines 24 .

[0031] The lower surface of the second dielectric substrate 21 is printed with a first metal base plate 25 on which a rectangular notch is etched. The upper surface of the second dielectric substrate 21 is printed with a metal patch 26 above the rectangular notch etched on the first metal base plate 25. The first metal base plate 25 and the metal patch 26 are connected via a metal through hole.

[0032] The lower surface of the third dielectric substrate 23 is printed with two groups of intersecting high-frequency dipole arms 27, which radiate high-frequency electromagnetic waves with polarizations of +45° and -45° respectively. Each group of high-frequency dipole arms is composed of two metal rings. The metal rings are octagonal ring structures, and the eight internal angles are all 135°. The upper surface of the third dielectric substrate 23 is printed with a coupling feeding structure 28, which is composed of a Y-shaped metal strip and a metal through hole.

[0033] The second dielectric substrate 21 and the third dielectric substrate 23 are both square in shape. Two groups of intersecting high-frequency dipole arms 27 printed on the upper surface of the third dielectric substrate 23 are located on two diagonal lines of the third dielectric substrate 23 .

[0034] The outer conductors at the lower ends of the two feeding coaxial lines 24 are connected to the metal patch 26 , and the ends of the coaxial lines are connected to the SMA RF connectors; the outer conductors at the upper ends of the two feeding coaxial lines 24 are connected to the high-frequency dipole arms 27 , and the inner conductors are connected to the coupling feeding structure 28 .

[0035] The high-frequency antenna unit 2 of the present invention uses a circular cross dipole with coaxial line coupling feeding, but the high-frequency antenna unit 2 can also use other types of dual-polarization base station antennas, such as patch antennas, cross-shaped cross dipoles, etc. The type of high-frequency antenna unit 2 will not affect the high-frequency electromagnetic transparency characteristics of the low-frequency radiation unit.

[0036] Reference Figure 3 and Figure 4 The low-frequency antenna unit 3 includes a low-frequency radiation unit consisting of a first dielectric substrate 31 and two groups of intersecting low-frequency dipole arms 32 printed on the upper surface thereof, and two baluns 34 .

[0037] The first dielectric substrate 31 is provided with two groups of rectangular mounting holes for mounting the fourth dielectric substrate 341 on its two diagonals; the two groups of low-frequency dipole arms 32 radiate low-frequency electromagnetic waves with polarizations of +45° and -45°, respectively, and there is a coupling gap between two adjacent hexagonal metal strips, and impedance matching is adjusted by adjusting the length and width of the gap; the low-frequency dipole arm 32 has an inner angle and an opposite angle close to the center of the low-frequency radiation unit of 90°, and the other four inner angles are 135°; the low-frequency dipole arm 32 is composed of two hexagonal metal strips, each metal ring is provided with four notches, and each notch is connected inwardly with a decoupling structure 35, and a rectangular metal patch is provided on the 90° inner angle close to the center of the low-frequency radiation unit to facilitate the connection between the low-frequency dipole arm 32 and the second metal bottom plate 343, and the mounting hole is provided in the middle of the rectangular metal patch; the four decoupling structures 35 are connected to the inner angles of the hexagonal metal strips of the low-frequency dipole arm 32 at 90°. °, when the high-frequency antenna is excited, most of the high-frequency induced current on the low-frequency dipole arm 32 is concentrated near the decoupling structure 35, and due to the guiding effect of the decoupling structure 35, a high-frequency induced current with an opposite direction is formed, so that the scattered wave is offset and the interference of the low-frequency radiation unit on the high-frequency electromagnetic wave is reduced. The flow direction of the induced current can be controlled by adjusting the position and size of the Y-shaped composite structure, thereby adjusting the electromagnetic transparent frequency band; the two upper arms of the Y-shaped composite structure are composited by two U-shaped metal strips connected on one side, and the other side of the two U-shaped metal strips forms the lower arm of the Y-shaped composite structure, which is connected to the gap position of the adjacent side of the hexagonal metal ring with an angle of 90°; the two upper arms of the Y-shaped composite structure are respectively parallel to the two adjacent sides with an inner angle of 135° near the position where the gap of the hexagonal metal strip is located; the decoupling structure and the low-frequency dipole arm 32 form a closed ring structure, which extends the current path of the low-frequency radiation unit while keeping the radiation aperture unchanged, thereby realizing miniaturization.

[0038] The two baluns 34 are fixed on the metal reflector 1 through the mounting base plate 33 by metal screws; the upper surface and the lower surface of the mounting base plate 33 are printed with rectangular metal patches, and the metal patches are respectively etched with rectangular and square notches to avoid short circuit between the metal microstrip line 342 and the second metal base plate 343; the two baluns 34 have the same structure, both including a fourth dielectric substrate 341 and a metal microstrip line 342 with a variable width printed on one surface thereof and a second metal base plate 343 with a rectangular gap etched in the middle of the other surface, wherein the two second metal base plates 343 on the two baluns are respectively connected to a group of low-frequency dipole arms 32, and the size of the microstrip line and the rectangular gap is adjusted to achieve The impedance matching of the low-frequency antenna unit 3 is now adjusted; two rectangular protruding dielectric blocks are provided at the upper end of the fourth dielectric substrate 341, which are convenient for being clamped and fixed with a group of rectangular mounting holes of the first dielectric substrate 31, and staggered clamping grooves are provided in the middle of the two fourth dielectric substrates 341 to clamp and fix the two baluns 34 together, and a rectangular protruding dielectric block is provided at the lower end to facilitate its clamping and fixing with the mounting base plate 33; the low-frequency radiation unit is arranged above the high-frequency array, and its projection on the reflection plate at least partially overlaps with the projection of the high-frequency array on the reflection plate, and the two baluns 34 are arranged longitudinally, with their top ends fixed to the low-frequency radiation unit and their bottom ends fixed to the metal reflection plate 1.

[0039] The low frequency antenna unit of this embodiment operates at 1.71-2.69 GHz, and the high frequency antenna unit operates at 3.4-5.0 GHz. However, the operating frequencies of the low frequency antenna unit and the high frequency antenna unit can be adjusted according to actual needs.

[0040] Embodiment 2: This embodiment has the same basic structure as Embodiment 1, except that the low-frequency dipole arm is composed of two quadrilateral metal rings, and the composite decoupling structure is T-shaped.

[0041] Reference Figure 5 The low-frequency dipole arm 32 is composed of two regular quadrilateral metal rings; the four decoupling structures 35 are all T-shaped composite structures, which are respectively connected to the four sides of the regular quadrilateral metal ring; the transverse arm of the T-shaped composite structure is composed of two U-shaped metal strips connected on one side, and the other sides of the two U-shaped metal strips are each connected with a short metal branch to form a longitudinal arm of the T-shaped composite structure, which is connected to the notch position on the side of the regular quadrilateral metal ring.

[0042] The following is a further description of the technical effects of the present invention in conjunction with the simulation results:

[0043] 1. Experimental conditions and contents:

[0044] The simulation experiment of the present invention uses the commercial electromagnetic simulation software HFSS_22.1 to perform modeling and simulation.

[0045] Experiment 1: The S parameters of the low-frequency antenna unit and the high-frequency antenna unit of Example 1 of the present invention are simulated, and the results are as follows: Figure 6 (a) and Figure 6 (b) as shown.

[0046] Experiment 2: The gain and horizontal plane pattern of Example 1 of the present invention and a single high-frequency antenna array are simulated and compared. The results are as follows: Figure 7 (a) and Figure 7 (b) is shown. The +45° polarization ports of two high-frequency antenna units located in the same column are excited simultaneously. The basic structure of the single high-frequency antenna array is the same as that of Example 1, except that the single high-frequency antenna array does not have a low-frequency antenna unit.

[0047] 2. Experimental results analysis:

[0048] Reference Figure 6 (a) In the 1.71-2.69 GHz frequency band, the reflection coefficients of the ±45° polarization ports of the low-frequency antenna unit are all less than -10 dB, and the isolation between ports with different polarizations is better than 28 dB.

[0049] Reference Figure 6 (b) In the 3.4-5.0GHz frequency band, the reflection coefficients of the ±45° polarization ports of the high-frequency antenna unit are all less than -14dB, and the isolation between ports with different polarizations is better than 24dB.

[0050] Reference Figure 7 (a) In the 3.4-5.0 GHz frequency band, the gain of Example 1 is stable in the range of 9.7-11.9 dBi, and the gain difference between it and the single high-frequency antenna array is 0-0.67 dB, indicating that in a wider frequency band, the gain performance of the high-frequency antenna unit is less affected by the low-frequency radiation unit, and the high-frequency electromagnetic waves can pass through the low-frequency radiation unit well.

[0051] Reference Figure 7 (b) When a single high-frequency antenna array is working, it has good directional radiation performance. The horizontal plane radiation pattern of Example 1 is close to that of a single high-frequency antenna array, and no obvious distortion occurs. Therefore, the composite decoupling structure provided by the present invention can effectively reduce the interference of the low-frequency radiation unit on the high-frequency pattern under the co-aperture layout, and has a good high-frequency pattern conformal effect.

[0052] Comprehensive experimental results show that the gain and horizontal plane radiation pattern performance of the high-frequency antenna unit in Example 1 are not significantly deteriorated due to the influence of the low-frequency antenna unit. Compared with the prior art, the operating bandwidth of the base station antenna array is effectively broadened. The low-frequency antenna unit of Example 1 operates at 1.71-2.69 GHz, and the high-frequency antenna unit operates at 3.4-5.0 GHz.

[0053] The above description and examples do not constitute any limitation to the present invention. It is obvious that for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims attached to the present invention.

Claims

1. A dual-frequency common aperture base station antenna array, comprising a metal reflector (1) and a high-frequency array consisting of a plurality of dual-polarization high-frequency antenna units (2) fixed thereon, and a dual-polarization low-frequency antenna unit (3) located in the middle of the high-frequency array; characterized in that: The high-frequency array is composed of 2*2 high-frequency antenna units (2); the low-frequency antenna unit (3) comprises a low-frequency radiation unit composed of a square first dielectric substrate (31) and two groups of intersecting low-frequency dipole arms (32) printed on the upper surface thereof, and two baluns (34); the low-frequency dipole arms (32) are composed of two quadrilateral or hexagonal metal rings, each of which is provided with four notches, each of which is connected inwardly to a composite decoupling structure (35); the low-frequency radiation unit is arranged above the high-frequency array, and its projection on the reflection plate at least partially overlaps with the projection of the high-frequency array on the reflection plate, and the two baluns (34) are arranged longitudinally, with their top ends fixed to the low-frequency radiation unit and their bottom ends fixed to the metal reflection plate (1).

2. The base station antenna array according to claim 1, characterized in that: The two baluns (34) are fixed on the metal reflector (1) via a mounting base plate (33).

3. The base station antenna array according to claim 1, characterized in that: The high-frequency antenna unit (2) comprises a square second dielectric substrate (21), a square third dielectric substrate (23) fixed on top of the second dielectric substrate (21) via a nylon column (22), and two feeding coaxial lines (24); a first metal base plate (25) is printed on the lower surface of the second dielectric substrate (21), a rectangular notch is etched on the first metal base plate (25), and a metal patch (26) is printed on the upper surface of the second dielectric substrate (21) above the rectangular notch etched on the first metal base plate (25); the third dielectric substrate (23) is fixed on the upper surface of the second dielectric substrate (21), and a first metal base plate (25) is printed on the lower surface of the second dielectric substrate (21). Two groups of intersecting high-frequency dipole arms (27) are printed on two diagonal lines on the lower surface of the substrate (23), each group of high-frequency dipole arms is composed of two octagonal metal rings, and a coupling feeding structure (28) is printed on the upper surface of the third dielectric substrate (23); the outer conductors at the lower ends of the two feeding coaxial lines (24) are connected to the metal patch (26), the outer conductors at the upper ends of the two feeding coaxial lines (24) are connected to the high-frequency dipole arms (27), and the inner conductors are connected to the coupling feeding structure (28).

4. The base station antenna array according to claim 1, characterized in that: The low-frequency dipole arm (32) is composed of two hexagonal metal rings, each of which is located on the diagonal of the first dielectric substrate (31) with one set of diagonals at 90°, and the other two sets of diagonals at 135°; the composite decoupling structure (35) is a Y-shaped composite structure connected to the gap positions on the two adjacent sides of the hexagonal metal ring with a diagonal angle of 90°.

5. The base station antenna array according to claim 4, characterized in that: The two upper arms of the Y-shaped composite structure are composed of two U-shaped metal strips connected on one side, and the other side of the two U-shaped metal strips forms the lower arm of the Y-shaped composite structure, which is connected to the gap position of the adjacent side of the hexagonal metal ring with a diagonal angle of 90°.

6. The base station antenna array according to claim 1, characterized in that: The low-frequency dipole arm (32) is composed of two regular quadrilateral metal rings; the four composite decoupling structures (35) are all T-shaped composite structures, respectively connected to the four sides of the regular quadrilateral metal ring.

7. The base station antenna array according to claim 6, characterized in that: The transverse arm of the T-shaped composite structure is composed of two U-shaped metal strips connected on one side, and the other sides of the two U-shaped metal strips are each connected to a short metal branch to form a longitudinal arm of the T-shaped composite structure, which is connected to the notch position on the edge of the regular quadrilateral metal ring.

8. The base station antenna array according to claim 1, characterized in that: The two baluns (34) have the same structure, both comprising a fourth dielectric substrate (341), a metal microstrip line (342) printed on one surface thereof, and a second metal base plate (343) etched with a rectangular gap in the middle of the other surface, wherein the two second metal base plates (343) on the two baluns are respectively connected to a group of low-frequency dipole arms (32), and the impedance matching of the low-frequency antenna unit (3) is adjusted by adjusting the size of the microstrip line and the rectangular gap.

9. The base station antenna array according to claim 8, characterized in that: The first dielectric substrate (31) is provided with a mounting hole for mounting a fourth dielectric substrate (341).

10. The base station antenna array according to claim 1, characterized in that: The intersection point of the two groups of mutually crossed low-frequency dipole arms (32) and the center of the high-frequency array are both located in the center normal direction of the first dielectric substrate (31).

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