A Wide-Bandwidth Beam Decoupling Antenna for Base Stations

Abstract

The present invention discloses a wide-bandwidth beam decoupling antenna for a base station, which is composed of a top-layer additional structure, a dipole, a balun, a trapezoidal ground plane, a metal ground and a support column. Taking a 1×2 antenna array as an example, the top-layer additional structure and the trapezoidal ground plane are used as the additional structures of the dipole antenna array, which are distributed above, in the middle and on both sides of the dipole array. By utilizing the triple functions of the metal strip of the top-layer additional structure and the trapezoidal ground plane for decoupling, beam broadening and matching adjustment respectively, and the effect of the H-shaped metal strip of the top-layer additional structure on H the broadening of the surface beam, combined with balun feeding, the wide-beam width bandwidth and the decoupling bandwidth are synchronously improved, and the comprehensive working bandwidth, the stability of the in-band beam width and the structural complexity can be taken into account.

Description

Technical Field

[0001] The present invention relates to a microwave communication device, and in particular to a broadband wide-beam decoupling antenna for base stations. Background Art

[0002] Base station antennas are key components in mobile communication systems. Broadband base station antennas can cover multiple frequency bands, which is beneficial for the compatibility of multiple communication systems, improving spectrum efficiency and reducing the number of base station antennas. At the same time, the half-power beam width is an important indicator of base station antennas. A wide beam width is beneficial for increasing the coverage area and reducing the number of sectors; a base station antenna with low mutual coupling is beneficial for ensuring the normal operation of the base station antenna array in terms of matching, radiation pattern, and efficiency. However, broadband base station antennas require both a wide half-power beam width and low mutual coupling between elements to maintain a wide operating bandwidth, that is, they need to meet broadband matching, broadband half-power beam width, and broadband decoupling in terms of performance. Therefore, it poses a great challenge but has important engineering application value.

[0003] Existing base station antennas do not have technologies that can simultaneously meet broadband wide-beam and broadband decoupling. Currently, there are two solutions for broadening the bandwidth corresponding to the wide beam width: the first is to combine a bent dipole arm with the addition of metal walls on both sides to construct magnetic dipoles with different operating frequencies inside the dipole and between the dipole arm and the metal wall, thereby achieving broadband beam broadening. However, the radiation of the high-frequency magnetic dipole is weak, resulting in the beam broadening frequency band being unable to cover the entire matching bandwidth; the second solution is to add a metal cylinder directly below the end of the bent metal arm of the wide-leaf magnetoelectric dipole to expand the beam broadening bandwidth through the adjustment of the vertical current on the dipole arm by the metal cylinder at different frequencies, but the beam width fluctuates greatly within the band. There are also two solutions for broadening the antenna decoupling bandwidth: the first is to stack a composite dielectric layer and an array decoupling layer and combine a multi-stub resonator with an enclosed distribution to achieve a reduction in mutual coupling across the entire frequency band. However, the decoupling bandwidth needs to be further broadened, and the overall structure complexity is relatively high; the second is to place metal strip resonators on the front, rear, and above the dipole to introduce multiple mutual coupling null points to broaden the decoupling bandwidth. However, due to the use of a large number of dielectric substrates, problems such as complex structure and high cost arise.

[0004] The above methods for improving the wide beam width bandwidth or decoupling bandwidth can only achieve the bandwidth broadening of each aspect unilaterally and cannot synchronously achieve the broadening of the common bandwidth of both. Summary of the Invention

[0005] Object of the Invention: Aiming at the above-mentioned existing technologies, a broadband wide-beam decoupling antenna for base stations is proposed, which can simultaneously meet broadband wide-beam and broadband decoupling, and can also take into account the comprehensive operating bandwidth, the stability of the beam width within the band, and the structure complexity.

[0006] Technical solution: A broadband wide-beam decoupling antenna for a base station, comprising a top additional structure, N dipoles, N baluns, (N + 1) trapezoidal ground planes, and a metal ground; N is a natural number greater than or equal to 2.

[0007] The top additional structure includes a top dielectric substrate, and (N + 1) metal strips are arranged uniformly at intervals along a straight line on the upper surface of the top dielectric substrate. Two H-shaped metal strips are symmetrically distributed in the gap between adjacent two metal strips with respect to the straight line.

[0008] The dipole includes a middle dielectric substrate and a half-wave dipole located on the lower surface of the middle dielectric substrate; N dipoles are horizontally arranged in a straight line direction below the top additional structure, and the centers of each dipole are respectively aligned with the midpoints of the gaps between the metal strips.

[0009] Each balun is respectively connected to a dipole and the metal ground; (N + 1) trapezoidal ground planes are arranged in parallel at equal intervals along the polarization direction, and are respectively located at the midpoints of the gaps between adjacent two dipoles and outside the two end dipoles.

[0010] Further, in the dipole, a pair of square air vias are arranged near the center feeding position of the two arms of the half-wave dipole.

[0011] The balun includes a vertical dielectric substrate, a bent metal strip, and two stepped metal strips; wherein, as a part of the vertical dielectric substrate, two narrow pins are symmetrically formed at the top end of the vertical dielectric substrate, and two wide pins are symmetrically formed at the bottom end; the bent metal strip is located on the front surface of the vertical dielectric substrate, and the bent metal strip is composed of a vertical part and a bent part connected to the top of the vertical part; the two stepped metal strips are symmetrically distributed on the back surface of the vertical dielectric substrate, and respectively cover a narrow pin and a wide pin; the area of one stepped metal strip covers the vertical part of the bent metal strip, and the bottom end of the vertical part of the bent metal strip is flush with the bottom end of the wide pin.

[0012] The main body of the metal ground is a rectangular metal sheet; the baluns are respectively inserted into the two square air vias of a dipole through two narrow pins, and are respectively inserted into the corresponding slots on the rectangular metal sheet through two wide pins.

[0013] Further, the distance between the top additional structure and the metal ground is between 0.35λ 0 - 0.39λ 0 where λ 0 is the free space wavelength corresponding to the center frequency; the length of the metal strip is between 0.28λ 0 - 0.32λ 0 and the length of the left and right arms of the H-shaped metal strip is between 0.14λ 0 - 0.18λ 0between, with the intermediate horizontal length being between 0.11λ 0 -0.15λ 0 between.

[0014] Furthermore, the height between the dipole and the metal ground is 0.23λ 0 -0.25λ 0 ; the height of the trapezoidal ground plane is between 0.19λ 0 -0.23λ 0 between, the width of the upper base is between 0.06λ 0 -0.10λ 0 between, and the width of the lower base is between 0.30λ 0 -0.34λ 0 between.

[0015] Beneficial effects: Existing wide-beam or decoupled base station antennas cannot simultaneously meet wide bandwidth wide-beam and wideband decoupling. They can only achieve wideband decoupling or wideband wide-beam separately, and there are problems such as relatively narrow combined working bandwidth, poor stability of in-band beam width, or complex structure. Taking a 1*2 antenna array as an example, the present invention uses the top additional structure and the trapezoidal ground plane as additional structures of the dipole antenna array, which are distributed above, in the middle, and on both sides of the dipole array. By utilizing the triple functions of the metal strips of the top additional structure and the trapezoidal ground plane for decoupling, beam broadening, and matching adjustment respectively, and the effect of the H-shaped metal strip of the top additional structure on H elevation beam broadening, combined with balun feeding, it realizes synchronous improvement of the wide-beam width bandwidth and decoupling bandwidth, and can take into account the combined working bandwidth, stability of in-band beam width, and structural complexity.

[0016] Specifically, the three metal strips of the top additional structure are symmetrically arranged in a straight line directly above the dipole array. The middle metal strip can not only form a new coupling path between two dipoles to cancel and generate high-frequency coupling zeros, but also combine with the metal strips on both sides to exert an oblique traction effect on the E elevation radiation of each dipole, generating E elevation beam broadening in the high-frequency band within the wide frequency band. At the same time, the three metal strips have an adjustment effect on the resonant frequency and matching degree of the antenna, which is beneficial for width matching.

[0017] The four H-shaped metal strips of the top additional structure are aligned with the two gaps between the metal strips and are symmetrically arranged on both sides of the metal strips. By utilizing the oblique traction effect of the H-shaped metal strips on H elevation radiation, it can broaden the H elevation beam width to a certain extent.

[0018] The three trapezoidal ground plates are arranged linearly and symmetrically along the polarization direction, respectively located in the middle and on both sides of the gap between the two dipoles. The middle trapezoidal ground plate can not only adjust the coupling path to generate a coupling zero point in the low frequency band of the working frequency band, but also can couple with the corresponding dipoles together with the trapezoidal ground plates on both sides to form a new resonant mode located in the low frequency band of the working frequency band. In addition, the multiple anti-phase vertical currents obtained by coupling the trapezoidal ground plate can greatly increase the resonant mode near the low frequency resonance point. E Surface beam width.

[0019] The balun consists of two narrow pins, a stepped metal strip, a vertical dielectric substrate, a bent metal strip, and two wide pins. The narrow pin and the wide pin are inserted into the dipole and the metal ground respectively, and the stepped metal strip is connected to the half-wave oscillator and the metal ground. The balun can provide differential excitation for the dipole, adjust the matching, and provide structural support for the dipole. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the three-dimensional structure of the wide bandwidth beam decoupling antenna for base stations of the present invention;

[0021] Figure 2 It is a schematic diagram of the top-layer additional structure of the wide bandwidth beam decoupling antenna for base stations of the present invention;

[0022] Figure 3 A schematic diagram of a dipole structure of a wide bandwidth beam decoupling antenna for a base station according to the present invention;

[0023] Figure 4 A schematic diagram of the balun structure of the wide bandwidth beam decoupling antenna for base stations of the present invention;

[0024] Figure 5 It is a schematic diagram of the metal ground structure of the wide bandwidth beam decoupling antenna for base stations of the present invention;

[0025] Figure 6 The present invention is different from the one without adding additional structure. S Parameter simulation result comparison chart;

[0026] Figure 7 The present invention is different from the one without adding additional structure. E noodle H Comparison chart of surface simulation beam width;

[0027] Figure 8 For the embodiment of the present invention E noodle H Surface simulation radiation patterns, where (a) corresponds to 3.6 GHz, (b) corresponds to 4 GHz, and (c) corresponds to 4.4 GHz. DETAILED DESCRIPTION

[0028] The present invention will be further explained below in conjunction with the accompanying drawings.

[0029] As Figure 1 shown, a broadband wide-beam decoupling antenna for a base station is composed of a top-layer additional structure 1, a dipole 2, a balun 3, a trapezoidal ground plane 4, a metal ground 5, and a support pillar 6.

[0030] This embodiment provides a 1×2 antenna array. As Figure 2 shown, the overall center of the top-layer additional structure 1 is symmetric, and it is composed of a top-layer dielectric substrate 101, three metal strips 102 located on the upper surface of the top-layer dielectric substrate 101, and four H-shaped metal strips 103. Among them, the three metal strips 102 are arranged evenly at intervals along a straight line. The four H-shaped metal strips 103 are aligned with the two gaps between the metal strips 102 and are symmetrically arranged on both sides of the metal strips 102. The overall top-layer additional structure 1 is supported at the uppermost part of the overall antenna by four support pillars 6 located at the four corners of the top-layer dielectric substrate 101. The bottom ends of the support pillars 6 are connected to the metal ground 5. The distance between the top-layer additional structure 1 and the metal ground 5 is between 0.35λ 0 -0.39λ 0 where λ 0 is the free-space wavelength corresponding to the center frequency; the length of the metal strip 102 is between 0.28λ 0 -0.32λ 0 the length of the left and right arms of the H-shaped metal strip 103 is between 0.14λ 0 -0.18λ 0 and the middle horizontal length is between 0.11λ 0 -0.15λ 0 .

[0031] As Figure 3 shown, the dipole 2 is composed of a middle-layer dielectric substrate 201, a half-wave dipole 202, and two square air vias 203, and the overall is centrosymmetric. Among them, the half-wave dipole 202 is located on the lower surface of the middle-layer dielectric substrate 201. The two arms of the half-wave dipole 202 are arranged in a straight line. The two square air vias 203 are symmetrically located on the two arms of the half-wave dipole 202 and are close to the center feeding point. The two dipoles 2 are horizontally arranged below the top-layer additional structure 1, and their centers are respectively aligned with the midpoints of the gaps between the metal strips 102. The height between the dipole 2 and the metal ground 5 is 0.23λ 0 -0.25λ 0 .

[0032] As Figure 4As shown in the figure, the balun 3 is composed of a vertical dielectric substrate 303, a bent metal strip 304, and two stepped metal strips 302. Among them, as a part of the vertical dielectric substrate 303, two narrow pins 301 are symmetrically formed at the top end of the vertical dielectric substrate 303, and two wide pins 305 are symmetrically formed at the bottom end. The bent metal strip 304 is located on the front side of the vertical dielectric substrate 303, and the bent metal strip 304 is composed of a vertical portion and a bent portion connected to the top end of the vertical portion. The two stepped metal strips 302 are symmetrically distributed on the back side of the vertical dielectric substrate 303 and respectively cover a narrow pin 301 and a wide pin 305. The area of one of the stepped metal strips 302 covers the vertical portion of the bent metal strip 304, and the bottom end of the vertical portion of the bent metal strip 304 is flush with the bottom end of the wide pin 305.

[0033] As Figure 5 shown, the main body of the metal ground 5 is a rectangular metal sheet 501, and two sets of slots for inserting the wide pins 305 at the bottom of the balun 3 are formed on the rectangular metal sheet 501. In each set of slots, one is a rectangular wide slot 502, and the other is a rectangular narrow slot 503. The size of the rectangular wide slot 502 is adapted to the wide pin 305 with the vertical portion of the bent metal strip 304.

[0034] As Figure 1 shown, the two baluns 3 are respectively inserted into two square air through-holes 203 of a dipole 2 through two narrow pins 301, and are respectively inserted into the rectangular wide slot 502 and the rectangular narrow slot 503 of the metal ground 5 through two wide pins 305, so that the stepped metal strip 302 is conductively connected to the half-wave dipole 202 and the metal ground 5. The three trapezoidal ground plates 4 are arranged in parallel at equal intervals along the polarization direction (i.e., the arrangement direction of the dipole arms), and are respectively located at the midpoint and both sides of the gap between the two dipoles 2. The height of the trapezoidal ground plate 4 is between 0.19λ 0 -0.23λ 0 and the width of the upper base is between 0.06λ 0 -0.10λ 0 and the width of the lower base is between 0.30λ 0 -0.34λ 0 and.

[0035] In the above structure, the dipole 2, the balun 3, and the metal ground 5 constitute the main body of the antenna unit; the top-layer additional structure 1 and the three trapezoidal ground plates 4 form the additional structure of the dipole antenna array. The bent metal strip 304 of the balun 3, the vertical dielectric substrate 303, and the stepped metal strip 302 form the microstrip feeder of the antenna.

[0036] For the above broadband wide-beam decoupled antenna, the signal is fed into the microstrip feeder of the balun 3 and coupled to each dipole 2. Under the combined action of the dipole 2 and its additional structure, a base station antenna that simultaneously satisfies broadband wide-beam and broadband decoupling is realized.

[0037] In this process, on the one hand, the middle metal strip 102 of the top additional structure 1 can bring a new coupling path for the two dipoles 2, so that it can cancel with the original coupling path to form a high-frequency coupling zero point, which helps to broaden the decoupling bandwidth; on the other hand, combined with the metal strips 102 on both sides, it has an oblique traction effect on the E surface radiation of each dipole 2, so it can broaden the E surface beam width, especially the E surface beam width in the high-frequency band within the frequency band, which can provide a basis for broadband beam broadening. At the same time, the three metal strips 102 on the top layer have an adjusting effect on the resonant frequency and matching degree of the antenna, which is beneficial to width matching. The four H-shaped strips 103 on the top layer have an oblique traction effect on the H surface radiation, thereby broadening the H surface beam width to a certain extent.

[0038] The trapezoidal ground plane 4 located in the middle can, on the one hand, adjust the coupling path to generate a coupling zero point in the low-frequency band of the working frequency band, which helps to broaden the decoupling bandwidth; on the other hand, together with the trapezoidal ground planes 4 on both sides, it couples with the corresponding dipoles 2 to form a new resonant mode in the low-frequency band of the working frequency band, which is beneficial to expanding the matching bandwidth. At the same time, the trapezoidal ground plane 4 couples to obtain an anti-phase vertical current, and the trapezoidal surface is conducive to constructing multiple vertical currents, which can greatly increase the E surface beam width near the low-frequency resonance point, and also provides a basis for broadband beam broadening.

[0039] Therefore, under the combined action of the top additional structure 1 and the trapezoidal ground plane 4, it is beneficial for the dipole array to simultaneously obtain broadband decoupling, broadband wide-beam and broadband matching, and the beam broadband stability within the band is good. The balun 3 below the dipole 2 can provide differential excitation for the dipole, adjust the matching, and provide structural support for the dipole.

[0040] The dielectric substrates used in this embodiment are all RO4003C, with a dielectric constant of 3.55, and the antenna size is 1.5λ 0 ×1.0λ 0 × 0.37λ 0 . Figure 6 The parameter simulation results of this embodiment and the case without additional structure are compared. From S the Figure 6It can be seen that before adding the additional structure, the matching frequency band of the antenna covers 3.69 - 5.13 GHz, that is, the relative bandwidth is 30%. The maximum coupling degree between units within the matching frequency band is -10 dB. After adding the additional structure in the present invention, the matching frequency band covers 3.28 - 4.8 GHz, that is, the relative bandwidth is broadened to 37.6%, the maximum coupling degree is only -22 dB, and the corresponding decoupling bandwidth can reach 40.6%. Figure 7 The E plane, H simulation results of the E plane beamwidth are compared between this embodiment and the case without the additional structure. When there is no additional structure, within the range of 3.8 - 4.7 GHz H the E plane beamwidth is between 46° and 73°, H and the E plane beamwidth is between 85° and 105°. After adding the additional structure, within the range of 3.3 - 4.7 GHz Figure 8 the E plane beamwidth is between 100° and 112°, H and the

[0041] plane beamwidth is between 98° and 122°. It can be seen that the beamwidth is significantly broadened, and the

[0042] plane beam stability within the wide frequency band is also improved. The simulated radiation patterns of this embodiment at 3.6 GHz, 4 GHz, and 4.4 GHz are The plane half-power beamwidths are 100°, 103°, and 103° respectively, and the plane half-power beamwidths are 103°, 110°, and 119°. The cross-polarization levels are all relatively low. Compared with the prior art, the present invention can simultaneously improve the wide beamwidth bandwidth and the decoupling bandwidth, and can also take into account the comprehensive operating bandwidth, the in-band beamwidth stability, and the structural complexity.

[0041] The 1×2 antenna array of this embodiment can be extended to a 1×N structure.

[0042] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A wide bandwidth beam decoupling antenna for a base station, characterized in that: It includes a top-layer additional structure (1), N dipoles (2), N baluns (3), (N+1) trapezoidal ground planes (4), and a metal ground (5); N is a natural number greater than or equal to 2; The top additional structure (1) comprises a top dielectric substrate (101), (N+1) metal strips (102) are evenly spaced and arranged on the upper surface of the top dielectric substrate (101) along the transverse symmetry axis of the top dielectric substrate (101), and two H-shaped metal strips (103) are symmetrically distributed in the gap between two adjacent metal strips (102) about the transverse symmetry axis of the top dielectric substrate (101); The dipole (2) comprises a middle dielectric substrate (201) and a half-wave oscillator (202) located on the lower surface of the middle dielectric substrate (201); the N dipoles (2) are horizontally arranged below the top additional structure (1) along the transverse symmetry axis of the top dielectric substrate (101), and the center of each dipole (2) is directly opposite to the midpoint of the gap between the metal strips (102); Each balun (3) is respectively connected to a dipole (2) and a metal ground (5); (N+1) trapezoidal ground plates (4) are arranged in parallel at equal intervals along the polarization direction and are respectively located at the midpoint of the gap between two adjacent dipoles (2) and outside the dipoles (2) at both ends.

2. The base station-oriented wide bandwidth beam decoupling antenna according to claim 1, characterized in that: In the dipole (2), two arms of the half-wave oscillator (202) are provided with a pair of square air holes (203) near the central feeding position; The balun (3) comprises a vertical dielectric substrate (303), a bent metal strip (304), and two stepped metal strips (302); wherein, as a part of the vertical dielectric substrate (303), the top of the vertical dielectric substrate (303) symmetrically forms two narrow pins (301), and the bottom of the vertical dielectric substrate (303) symmetrically forms two wide pins (305); the bent metal strip (304) is located on the front side of the vertical dielectric substrate (303), and the bent metal strip (304) is composed of a vertical portion and a bent portion connected to the top of the vertical portion; the two stepped metal strips (302) are symmetrically distributed on the back side of the vertical dielectric substrate (303), and respectively cover a narrow pin (301) and a wide pin (305); an area of ​​one of the stepped metal strips (302) covers the vertical portion of the bent metal strip (304), and the bottom end of the vertical portion of the bent metal strip (304) is flush with the bottom end of the wide pin (305); The main body of the metal ground (5) is a rectangular metal sheet (501); the balun (3) is respectively inserted into two square air holes (203) of a dipole (2) through two narrow pins (301), and is respectively inserted into corresponding slots on the rectangular metal sheet (501) through two wide pins (305).

3. The base station-oriented wide bandwidth beam decoupling antenna according to claim 1 or 2, characterized in that: The distance between the top additional structure (1) and the metal ground (5) is between 0.35λ0-0.39λ0, where λ0 is the free space wavelength corresponding to the center frequency; the length of the metal strip (102) is between 0.28λ0-0.32λ0, the length of the left and right arms of the H-shaped metal strip (103) is between 0.14λ0-0.18λ0, and the middle horizontal length is between 0.11λ0-0.15λ0.

4. The base station-oriented wide bandwidth beam decoupling antenna according to claim 3, characterized in that: The height between the dipole (2) and the metal ground (5) is 0.23λ0-0.25λ0; the height of the trapezoidal ground plate (4) is between 0.19λ0-0.23λ0, the upper base width is between 0.06λ0-0.10λ0, and the lower base width is between 0.30λ0-0.34λ0.

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