A low profile dual-polarization indoor distributed antenna

Abstract

The low-profile dual-polarization indoor distributed antenna of the present invention comprises a first horizontal polarization unit, a second horizontal polarization unit and a vertical polarization unit. The metal ground of the first horizontal polarization unit is engraved with four rectangular grooves, and the upper surface of the dielectric substrate is provided with eight arc-shaped directors; the metal ground of the second horizontal polarization unit is engraved with eight arc-shaped grooves and rectangular grooves; the vertical polarization unit comprises four orthogonally arranged wavy radiation arms, which ensure wide-band omnidirectional radiation while its profile height is only 5% of the vacuum wavelength at the lowest operating frequency, which largely makes up for the defect of large profile size commonly existing in existing indoor distributed antennas. The first horizontal polarization unit achieves a bandwidth of 19.6% (3.26GHz-3.97GHz), the second horizontal polarization unit achieves a bandwidth of 49.2% (1.64GHz-2.71GHz), and the vertical polarization unit achieves a bandwidth of 84.0% (1.65GHz-4.04GHz).

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a low-profile dual-polarization indoor distributed antenna. Background Art

[0002] In current mobile communications, the data traffic of indoor communications has surged, and people's demand for indoor base stations is increasing. Among them, omnidirectional antennas that can achieve 360° full signal coverage are the first choice for indoor base stations. With the large-scale commercial use of 5G, the application of 5G antennas has become common. At the same time, the 2G / 3G / LTE frequency bands still play an important role in the evolution of communication technology. Indoor Internet access requires indoor distributed systems to transmit signals to the source and destination. Therefore, the development of antennas covering the 2G / 3G / LTE / 5G frequency bands has a good application prospect. The 1.7 ~ 2.7 GHz frequency band is an important application of the 4G LTE (long-term evolution) network and has attracted much attention in base station antenna design. In addition, N78 (3.3-3.8 GHz) is one of the main frequency bands for 5G communication deployment and testing. Since indoor distributed antennas are mostly installed on the ceiling, the lower profile is conducive to saving space and is also more beautiful. Therefore, there is an urgent need for low-profile indoor distributed antennas that can cover two frequency bands at the same time.

[0003] At present, when indoor distributed antennas realize dual polarization, it is generally completed by combining two omnidirectional radiation units: a vertical polarization unit and a horizontal polarization unit. The vertical polarization unit is generally realized by a monopole antenna or a conical antenna, which is easy to achieve a wider frequency coverage, but the cross-sectional size is large and the manufacturing cost is high. Non-circularity is an important indicator to measure the radiation performance of omnidirectional antennas. Existing horizontally polarized antennas rarely achieve low non-circularity, which makes it difficult to apply in occasions with high radiation performance requirements. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and propose a low-profile dual-polarization indoor distributed antenna, which realizes the low profile and small non-circularity of the antenna and effectively solves the problem of large cross-sectional size and large non-circularity of the existing dual-polarization antenna.

[0005] To achieve the purpose of the present invention, the present invention proposes a low-profile dual-polarization indoor distributed antenna, comprising a first horizontal polarization unit, a second horizontal polarization unit and a vertical polarization unit located therebetween, wherein the first horizontal polarization unit comprises a first dielectric substrate, a first feeding network and a first metal ground respectively printed on the upper and lower surfaces of the first dielectric substrate; the second horizontal polarization unit comprises a second dielectric substrate, a second feeding network and a second metal ground respectively printed on the upper and lower surfaces of the second dielectric substrate; the vertical polarization unit comprises four orthogonally arranged radiating arms, characterized in that: the radiating arms are wavy, the first horizontal polarization unit is supported overhead above the second horizontal polarization unit through the radiating arms, the top of the radiating arm is fixedly connected to the first metal ground, the outer end of the radiating arm is connected to the second metal ground after passing through the second dielectric substrate, the first metal ground is engraved with first grooves corresponding to the feeding arms of the first feeding network, and the second metal ground is engraved with second grooves corresponding to the feeding arms of the second feeding network.

[0006] Furthermore, the first horizontal polarization unit also includes eight arc directors printed on the upper surface of the first dielectric substrate and arranged along the circumferential direction for reducing the non-circularity of the azimuth plane pattern of the first horizontal polarization unit.

[0007] Furthermore, both sides of the outer ends of the second slots have inwardly facing arc structures, and rectangular slots for further reducing the non-circularity of the azimuth plane pattern of the first horizontal polarization unit are arranged between adjacent second slots.

[0008] In the low-profile dual-polarization indoor distributed antenna of the present invention, the unique wavy radiating arm can provide good omnidirectional radiation performance similar to that of a monopole, and the wavy radiating arm is conducive to reducing the height of the antenna. In addition, the radiating arm also serves as a supporting component of the first horizontal polarization unit; the metal ground of the first horizontal polarization unit extends the current path on the radiating arm, which facilitates further reducing the height of the antenna to meet the application requirements of the low profile.

[0009] In the low-profile dual-polarization indoor distributed antenna of the present invention, the eight arc-shaped directors at the outermost ends of the upper surface of the dielectric substrate of the first horizontal polarization unit can reduce the out-of-roundness of the first horizontal polarization unit, and eight rectangular grooves engraved on the metal ground of the second horizontal polarization unit can further improve the out-of-roundness of the first horizontal polarization unit.

[0010] In the low-profile dual-polarization indoor distributed antenna of the present invention, the combination of the wavy radiation arm and the top metal ground ensures wide-band omnidirectional radiation while its profile height is only 5% of the vacuum wavelength at the lowest operating frequency; the combination of eight arc directors and eight rectangular slots can reduce the out-of-roundness of the antenna to less than 3dB, which largely makes up for the defects of large profile size and large out-of-roundness commonly found in existing indoor distributed antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A structural perspective view of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0012] Figure 2 A front view of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0013] Figure 3 A top view of a first horizontal polarization unit of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0014] Figure 4 A top view of a second horizontal polarization unit of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0015] Figure 5 The present invention discloses a current distribution diagram on a radiation arm of a low-profile dual-polarization indoor distributed antenna.

[0016] Figure 6 The electric field distribution diagram is when the input port of the vertical polarization unit of the low-profile dual-polarization indoor distributed antenna involved in the present invention is excited.

[0017] Figure 7 The figure is a current distribution diagram on the metal ground 12 when the input port of the first horizontal polarization unit of the low-profile dual-polarization indoor distributed antenna involved in the present invention is excited.

[0018] Figure 8 The figure is a current distribution diagram on the metal ground 22 when the input port of the second horizontal polarization unit of the low-profile dual-polarization indoor distributed antenna of the present invention is excited.

[0019] Fig. 9 A reflection coefficient and peak gain curve diagram of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0020] Fig.10 An isolation diagram of a low-profile dual-polarization indoor distributed antenna according to the present invention;

[0021] Fig.11 The directional diagram of the first horizontal polarization unit of a low-profile dual-polarization indoor distributed antenna of the present invention at a frequency point of 3.55 GHz;

[0022] Fig.12 The directional diagram of the second horizontal polarization unit of a low-profile dual-polarization indoor distributed antenna according to the present invention at a frequency point of 2.0 GHz;

[0023] Fig.13 The directional diagram of the second horizontal polarization unit of a low-profile dual-polarization indoor distributed antenna according to the present invention at a frequency point of 2.4 GHz;

[0024] Fig.14 The directional diagram of the vertical polarization unit of a low-profile dual-polarization indoor distributed antenna of the present invention at a frequency point of 2.0 GHz;

[0025] Fig.15 The directional diagram of the vertical polarization unit of a low-profile dual-polarization indoor distributed antenna of the present invention at a frequency point of 2.4 GHz;

[0026] Fig.16 The directional diagram of the vertical polarization unit of a low-profile dual-polarization indoor distributed antenna of the present invention at a frequency point of 3.55 GHz;

[0027] In the accompanying drawings, 1-first horizontal polarization unit; 11-first dielectric substrate; 12-first metal ground; 121-first slot; 13-first feeding network; 131-first input port; 132-one-to-four power divider; 133-first feeding arm; 14-arc director; 2-second horizontal polarization unit; 21-second dielectric substrate; 224-rectangular through hole; 22-second metal ground; 221-second slot; 222-rectangular slot; 223-central hole; 23-second feeding network; 231-second input port; 232-one-to-eight power divider; 233-second feeding arm; 3-radiating arm; 4-coaxial feeding input port. DETAILED DESCRIPTION

[0028] The present invention is further explained below in detail with reference to the accompanying drawings so that those skilled in the art can more deeply understand the present invention and be able to implement it. However, the following reference examples are only used to explain the present invention and are not intended to limit the present invention.

[0029] Figure 1 The present invention is a structural perspective view of a low-profile dual-polarization indoor distributed antenna, which includes a first horizontal polarization unit 1, a second horizontal polarization unit 2 and a vertical polarization unit located therebetween.

[0030] The first horizontal polarization unit 1 includes a first dielectric substrate 11, a first feeding network 13 and eight arc directors 14 printed on the upper surface of the first dielectric substrate 11, and a first metal ground 12 printed on the lower surface of the first dielectric substrate 11. The first metal ground 12 is engraved with first grooves 121 corresponding to the feeding arms of the first feeding network 13.

[0031] The second horizontal polarization unit 2 comprises a second dielectric substrate 21, a second feeding network 23 printed on the upper and lower surfaces of the second dielectric substrate 21, and a second metal ground 22. The second metal ground 22 is engraved with second grooves 221 corresponding to the feeding arms of the second feeding network 23.

[0032] The first dielectric substrate 11 , the second dielectric substrate 21 , the first metal ground 12 and the second metal ground 22 are circular in shape, and the centers of the four circles are located on the same vertical line.

[0033] The vertical polarization unit includes four orthogonally arranged radiation arms 3. Figure 2 As shown, the radiation arm 3 is wavy, and in this example, the radiation arm 3 is formed by a rectangular metal sheet that is bent several times. The first horizontal polarization unit 1 is supported overhead above the second horizontal polarization unit 2 through the radiation arm 3. The top of the radiation arm 3 is fixedly connected to the first metal ground 12, so that the first metal ground 21 of the first horizontal polarization unit 1 extends the current path on the radiation arm 3, which is convenient for reducing the antenna height to meet the application requirements of low profile; the four mutually perpendicular radiation arms 3 are bent several times, which can provide good omnidirectional radiation performance similar to that of a monopole, and is also conducive to reducing the antenna height. The outer end of the radiation arm 3 passes through the second dielectric substrate 21 and is connected to the second metal ground 22, and the bottom of the radiation arm 3 within the outer end falls on the second dielectric substrate 21.

[0034] The present invention relates to a low-profile dual-polarization indoor distributed antenna, which utilizes a first metal ground 12 and four mutually perpendicular radiation arms 3 to achieve broadband omnidirectional radiation performance of a vertically polarized unit, and its cross-sectional size is only 0.05λ low (λ low is the wavelength in free space at the lowest operating frequency of the antenna), which largely makes up for the defect of large cross-sectional size that is common in existing similar antennas.

[0035] In the specific structural design, a coaxial feeding input port 4 is provided at the central hole 223 at the bottom of the second metal ground 22, and the coaxial cable is inserted upward from the central hole 223 at the bottom of the second metal ground 22, the inner conductor of the coaxial cable is connected to the inner end of the radiation arm 3, the outer conductor of the coaxial cable is connected to the second metal ground 22, and the coaxial cable is fixed through the coaxial feeding input port 4.

[0036] like Figure 3 As shown, the first feeding network 13 of the first horizontal polarization unit 1 is printed on the upper surface of the dielectric substrate 11, including a first input port 131, a one-to-four power divider 132 and four first feeding arms; four rectangular first slots 121 are dug out on the first metal ground 12, and the first slots 121 are arranged in a circular array and are arranged one by one directly below the first feeding arm 133. Each slot provides radiation in the direction of its slot opening, so as to realize the omnidirectional radiation of the first horizontal polarization unit 1; eight arc-shaped directors 14 are printed on the upper surface of the first dielectric substrate 11, which can reduce the out-of-roundness of the antenna.

[0037] like Figure 4As shown, in the second horizontal polarization unit 2, the second feeding network 23 is printed on the upper surface of the second dielectric substrate 21, including a second input port 231, a one-to-eight power divider 232 and eight second feeding arms 233; eight arc-shaped second slots 221 are dug out on the second metal ground 22, and the second slots 221 are arranged in a circular array and are arranged one by one directly below the second feeding arms 233. Each slot provides radiation in the direction of its slot opening, so as to realize the omnidirectional radiation of the second horizontal polarization unit 2. Eight rectangular slots 222 are engraved between the eight arc-shaped second slots 221, so as to further improve the non-circularity of the azimuth plane pattern of the first horizontal polarization unit 1 to less than 3dB.

[0038] In this example, the first input port 131 is connected to the inner core of the SMA feed head of the first horizontal polarization unit 1, and the outer core of the SMA feed head of the first horizontal polarization unit 1 is connected to the first metal ground 12; the second input port 231 is connected to the inner core of the SMA feed head of the second horizontal polarization unit 2, and the outer core of the SMA feed head of the second horizontal polarization unit 2 is connected to the second metal ground 22. The first feeding network 13 and the second feeding network 23, the radiating arm 3, the first metal ground 12, and the second metal ground 22 are made of copper, and the first dielectric substrate 11 and the second dielectric substrate 21 are Rogers RO4003C dielectric substrates.

[0039] The embodiment of the present invention optimizes the size of each part of the antenna. The specific parameters of the antenna are shown in Table 1 below:

[0040] Table 1

[0041]

[0042] In Table 1, r 1 is the radius of the first dielectric substrate 11, r 2 is the radius of the second dielectric substrate 21 and the second metal ground 22, r 3 is the radius of the first metal ground 12, l s1 is the length of the second slot 221, l s2 is the length of the rectangular slot 222, l 1 is the length of the first groove 121, w s1 is the width of the second groove 221, w s2 is the width of the rectangular slot 222, w 1 is the width of the first groove 121, w d is the width of the arc director 14, t 1 is the thickness of the first dielectric substrate 11, t 2 is the thickness of the second dielectric substrate 21, lis the distance between the tops of two adjacent segments on the radiating arm 3, h is the distance between the dielectric substrate 11 and the dielectric substrate 21, a is the width of each metal arm, θ 1 is the angle of the four arc-shaped directors 14 opposite to the rectangular slot 121, θ 2 is the angle of the other four arc directors 14.

[0043] Figure 5 The current distribution diagram on the radiation arm of a low-profile dual-polarization indoor distributed antenna according to the present invention is shown. The currents on the radiation arms have the same phase and direction.

[0044] Figure 6 The electric field distribution diagram of the vertical polarization unit of the low-profile dual-polarization indoor distributed antenna of the present invention is shown when the input port is excited. The electric field direction is vertically upward, showing the characteristics of vertical polarization.

[0045] Figure 7 The current distribution diagram on the first metal ground when the input port of the first horizontal polarization unit of the low-profile dual-polarization indoor distributed antenna of the present invention is excited is shown. A clockwise circular current is formed, indicating that the first feeding network excites the four first slots on the first metal ground to form omnidirectional radiation.

[0046] Figure 8 The current distribution diagram on the metal ground when the input port of the second horizontal polarization unit of the low-profile dual-polarization indoor distributed antenna of the present invention is excited is shown. A counterclockwise circular current is formed, indicating that the second feeding network excites eight arc-shaped second slots on the second metal ground to form omnidirectional radiation.

[0047] Fig. 9 The reflection coefficient and peak gain curve of a low-profile dual-polarization indoor distributed antenna involved in the present invention are demonstrated. The results show that the relative bandwidth of the first horizontal polarization unit of the design is 19.6% (3.26GHz-3.97GHz), and the in-band peak gain is between 5dBi and 6dBi; the relative bandwidth of the second horizontal polarization unit is 49.2% (1.64GHz-2.71GHz), and the in-band peak gain is between 2.5dBi and 6dBi; the relative bandwidth of the vertical polarization unit is 84.0% (1.65GHz-4.04GHz), and the in-band peak gain is between 2.5dBi and 6dBi.

[0048] Fig.10 The isolation diagram of a low-profile dual-polarization indoor distributed antenna involved in the present invention is shown, and the results show that within the corresponding working frequency band, the isolation between any two of the three ports is greater than 25dB.

[0049] Fig.11 The radiation pattern of the first horizontal polarization unit at 3.55GHz is shown. The results show that the radiation pattern of the design has good consistency within the working frequency band, and the omnidirectional radiation performance of the first horizontal polarization unit is good.

[0050] Fig.12 , Fig.13 The radiation patterns of the second horizontal polarization unit at 2.0GHz and 2.4GHz are shown. The results show that the radiation patterns of the design have good consistency within the working frequency band, and the omnidirectional radiation performance of the second horizontal polarization unit is good.

[0051] Fig.14 , Fig.15 and Fig.16 The radiation patterns of the vertically polarized unit at 2.0 GHz, 2.4 GHz and 3.55 GHz are shown. The results show that the radiation patterns of the design have good consistency within the working frequency band, and the omnidirectional radiation performance of the vertically polarized unit is good.

[0052] The specific implementation scheme described above further describes in detail the purpose, technical scheme and beneficial effects of the present invention. It should be understood that the above is only a specific implementation scheme of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention.

Claims

1. A low-profile dual-polarization indoor distributed antenna, comprising a first horizontal polarization unit (1), a second horizontal polarization unit (2) and a vertical polarization unit located therebetween, wherein the first horizontal polarization unit (1) comprises a first dielectric substrate (11), a first feeding network (13) and a first metal ground (12) printed on the upper and lower surfaces of the first dielectric substrate (11), respectively; the second horizontal polarization unit (2) comprises a second dielectric substrate (21), a second feeding network (23) and a second metal ground (22) printed on the upper and lower surfaces of the second dielectric substrate (21), respectively; the vertical polarization unit comprises four orthogonally arranged radiation arms (3), characterized in that: The radiation arm (3) is in a wavy shape; the first horizontal polarization unit (1) is supported overhead above the second horizontal polarization unit (2) by the radiation arm (3); the top of the radiation arm (3) is fixedly connected to the first metal ground (12); the outer end of the radiation arm (3) passes through the second dielectric substrate (21) and is connected to the second metal ground (22); the first metal ground (12) is engraved with first grooves (121) corresponding one-to-one to the feeding arms of the first feeding network (13); and the second metal ground (22) is engraved with second grooves (221) corresponding one-to-one to the feeding arms of the second feeding network (23); A coaxial feed input port (4) is provided at the central hole (223) at the bottom of the second metal ground (22); a coaxial cable is inserted upward from the central hole (223) at the bottom of the second metal ground (22); an inner conductor of the coaxial cable is connected to the inner end of the radiation arm (3); an outer conductor of the coaxial cable is connected to the second metal ground (22); and the coaxial cable is fixed via the coaxial feed input port (4).

2. A low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: The radiation arm (3) is formed by bending a rectangular metal sheet several times.

3. The low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: The first dielectric substrate (11), the second dielectric substrate (21), the first metal ground (12) and the second metal ground (22) are circular in shape, and the centers of the four circles are located on the same vertical line.

4. The low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: Four rectangular through holes (224) are provided at positions of the second dielectric substrate (21) corresponding to the outer ends of the radiation arms (3); the outer ends of the radiation arms (3) are connected to the second metal ground (22) after being inserted into the rectangular through holes (224).

5. The low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: The first horizontal polarization unit (1) further comprises eight arc-shaped directors (14) printed on the upper surface of the first dielectric substrate (11) and arranged in a circumferential direction, and used to reduce the non-circularity of the azimuth plane pattern of the first horizontal polarization unit (1).

6. A low-profile dual-polarization indoor distributed antenna according to claim 5, characterized in that: Both sides of the outer ends of the second slots (221) have inwardly facing arc structures, and rectangular slots (222) are arranged between adjacent second slots (221) to further reduce the non-circularity of the azimuth plane pattern of the first horizontal polarization unit (1).

7. The low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: The first feeding network (13) comprises a first input port (131), a one-to-four power splitter (132) and four first feeding arms (133), the four first feeding arms (133) being arranged along a circular array, the first metal ground (12) being engraved with four first grooves (121), the first grooves (121) being arranged one-to-one directly below the first feeding arms (133); the second feeding network (23) comprises a second input port (231), a one-to-eight power splitter (232) and eight second feeding arms (233), the eight second feeding arms (233) being arranged along a circular array, the second metal ground (22) being engraved with eight second grooves (221), the second grooves (221) being arranged one-to-one directly below the second feeding arms (233).

8. A low-profile dual-polarization indoor distributed antenna according to claim 7, characterized in that: The first input port (131) is connected to the inner core of the SMA feed head of the first horizontal polarization unit (1), and the outer core of the SMA feed head of the first horizontal polarization unit (1) is connected to the first metal ground (12); the second input port (231) is connected to the inner core of the SMA feed head of the second horizontal polarization unit (2), and the outer core of the SMA feed head of the second horizontal polarization unit (2) is connected to the second metal ground (22).

9. The low-profile dual-polarization indoor distributed antenna according to claim 1, characterized in that: The first feeding network (13), the second feeding network (23), the radiating arm (3), the first metal ground (12), and the second metal ground (22) are made of copper, and the first dielectric substrate (11) and the second dielectric substrate (21) are Rogers RO4003C dielectric substrates.

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