Broadband low-profile dual-polarized omnidirectional antenna

Abstract

The broadband low-profile dual-polarization omnidirectional antenna comprises a horizontal polarization radiator, a metal coupling patch, a vertical polarization radiator and a metal floor which are sequentially arranged from top to bottom, the horizontal polarization radiator comprises a dielectric substrate, and a horizontal polarization radiation patch and a feed network which are printed on the upper surface and the lower surface of the dielectric substrate; the metal coupling patch comprises a metal disc and a metal circular ring nested on the circumference of the metal disc; the horizontal polarization radiation patch is connected with the metal disc through a first short-circuit line, and the metal ring and the horizontal polarization radiation patch are connected with the metal floor through four second short-circuit lines and four third short-circuit lines respectively. Through short-circuit connection between the horizontal polarization radiation patch and the metal disc and between the metal circular ring and the horizontal polarization radiation patch and the metal floor, coupling between the horizontal polarization radiation body and the vertical polarization radiation body is achieved, the electrical length of the antenna is further prolonged, the bandwidth of the antenna can be effectively widened, and the profile of the antenna can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas and relates to a broadband low-profile dual-polarization omnidirectional antenna which can be used for indoor communication and mobile base stations. Background Art

[0002] Mobile communications are constantly developing. In current mobile communications, 2G / 3G / LTE frequency bands still play an indispensable role. In the future, 5G and 2G / 3G / LTE will coexist for a long time. Therefore, the demand for antennas that can cover these frequency bands at the same time is increasing. Dual-polarized omnidirectional antennas are widely used in indoor communications due to their anti-multipath fading characteristics and high channel capacity. This can improve indoor signal coverage and system capacity, especially low-profile performance, meeting the current demand for multi-antenna technology.

[0003] Dual-polarized omnidirectional antennas usually include a vertically polarized VP omnidirectional antenna and a horizontally polarized HP omnidirectional antenna. The VP antenna can be implemented with a monopole, using a single cone shape to achieve broadband characteristics, and loaded with a metal top loading disk to improve impedance matching. An array consisting of multiple dipole antennas and a power divider feeding network can be used as an option for HP antennas. An array consisting of multiple tapered slot antennas can also achieve horizontal omnidirectional radiation with a wider bandwidth. Depending on different application requirements, the dual polarization can be composed of an HP antenna placed above the VP antenna, an HP antenna placed below the VP antenna, or an HP antenna embedded in the middle of the VP antenna.

[0004] In order to improve antenna performance and meet the requirements of wider bandwidth and smaller size, for example, the patent application with application publication number CN115863950A and titled "A dual-polarization omnidirectional antenna for indoor distribution" includes a vertical polarization unit and a horizontal polarization unit. The vertical polarization unit includes two vertically placed metal patches, a top-loaded metal disk and a vertical polarization unit input port. The horizontal polarization unit includes a dielectric substrate, a metal ground and a dielectric resonator. The lower surface of the dielectric substrate is provided with a feeding structure. The dielectric resonator is in the shape of a ring and has a truncated cone-shaped notch in the center. A pair of arc-shaped metal vibrators located above the dielectric substrate are symmetrically arranged on both sides of the metal ground. The arc-shaped metal vibrator includes two vibrator arms and open-circuit branches, and four parasitic patches are symmetrically arranged on the outer side of the arc-shaped metal vibrator. While ensuring wide-band omnidirectional radiation, the invention reduces the planar size of the antenna, but due to the lack of coupling loading between the vertical polarization unit and the horizontal polarization unit, the overlapping bandwidth is narrow, only 30%, and the profile is still high. 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 broadband low-profile dual-polarization omnidirectional antenna to solve the technical problems of narrow bandwidth and high profile in the prior art.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a horizontally polarized radiator 1, a metal coupling patch 2, a vertically polarized radiator 3 and a metal floor 4 arranged in sequence from top to bottom; the horizontally polarized radiator 1 includes a dielectric substrate 11 and a horizontally polarized radiating patch 12 and a feeding network 13 printed on the upper and lower surfaces thereof; the metal coupling patch 2 includes a metal disk 21 and a metal ring 22 nested on its circumference; the horizontally polarized radiating patch 12 is connected to the metal disk 21 through a first short-circuit line 5, and the metal ring 22 and the horizontally polarized radiating patch 12 are connected to the metal floor 4 through four second short-circuit lines 6 and four third short-circuit lines 7, respectively.

[0007] As an optimization, the dielectric substrate 11 and the metal floor 4 are both circular in shape, and the center normals of the dielectric substrate 11 , the metal floor 4 and the metal coupling patch 2 coincide with each other.

[0008] As an optimization, the horizontally polarized radiation patch 12 includes a circular patch 121 and four centrally symmetrically distributed dipole antenna units 122 and a microstrip line 123 connected thereto; four first rectangular slots 124 are etched on the circular patch 121; the dipole antenna unit 122 adopts a quasi-T-shaped structure with an arc-shaped transverse arm, a rectangular notch is etched in the middle of the transverse arm, a second rectangular slot 125 is etched on the longitudinal arm, and a third rectangular slot 126 is etched between the second rectangular slot 125 and the bottom of the rectangular notch; an arc-shaped director 127 is printed on each of the edges of the center of the four dipole antenna units 122 close to the circumference of the dielectric substrate 11.

[0009] As an optimization, four arc-shaped parasitic patches 8 are printed on the lower surface of the dielectric substrate 11 , and the four arc-shaped parasitic patches intersect with the projections of the four microstrip lines 123 respectively.

[0010] As an optimization, the horizontally polarized radiation patch 12 includes four centrosymmetrically distributed microstrip lines 123 on a circular patch 121 , which are respectively located on the angle bisectors between adjacent dipole antenna units 122 .

[0011] As an optimization, the four microstrip lines 123 symmetrically distributed at the center are connected to the metal floor 4 through four third short-circuit lines 7 respectively.

[0012] As an optimization, the center of the horizontally polarized radiation patch 12 is located on the center normal line of the dielectric substrate 11 .

[0013] As an optimization, the feeding network 13 adopts a one-to-four power divider, whose input port 131 is connected to an external coaxial line, and the ends of the four output ports are respectively connected to a reverse extension branch 132, and the four output ports are respectively connected to the third rectangular slots 126 etched on the four dipole antenna units 122 to achieve coupling feeding of the horizontally polarized radiation patch 12.

[0014] As an optimization, the centers of the metal disk 21 and the metal ring 22 of the metal coupling patch 2 are both located on the central axis of the vertically polarized radiator 3 .

[0015] As an optimization, the vertically polarized radiator 3 adopts a hollow inverted disk-cone structure, and the diameter of the disk-cone bottom is smaller than the diameter of the metal ring 22 .

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

[0017] The present invention connects the horizontally polarized radiation patch and the metal disk through the first short-circuit line, and the metal ring and the horizontally polarized radiation patch are connected to the metal floor through four second short-circuit lines and four third short-circuit lines respectively, thereby realizing the coupling between the horizontally polarized radiator and the vertically polarized radiator, thereby bringing about equivalent capacitance and equivalent inductance, and extending the electrical length of the antenna. Compared with the prior art, the bandwidth of the antenna is effectively broadened, and the cross-section of the antenna is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 for Figure 1 Side view of

[0020] Figure 3 It is a schematic diagram of the structure of the horizontally polarized radiation patch of the present invention;

[0021] Figure 4 It is a structural schematic diagram of the feeding network of the present invention;

[0022] Figure 5 is the impedance matching coefficient of the vertical polarization element before and after the loaded microstrip line and the short-circuit line in the embodiment of the present invention |S 11 |、Impedance matching coefficient of horizontal polarization element before and after loading microstrip line and short-circuit line|S 22 | and the isolation between horizontally polarized components and vertically polarized components |S 21 |Graph of the relationship between the curve and the frequency;

[0023] Figure 6 The normalized radiation patterns of the vertically polarized element of the embodiment of the present invention at 2 GHz, 2.7 GHz, 3.3 GHz and 3.6 GHz respectively on the E-plane xoz plane;

[0024] Figure 7 The normalized radiation patterns of the H-plane xoy-plane of the vertically polarized element in the embodiment of the present invention working at 2 GHz, 2.7 GHz, 3.3 GHz and 3.6 GHz respectively;

[0025] Figure 8 The normalized radiation patterns of the horizontally polarized element of the embodiment of the present invention at 2 GHz, 2.7 GHz, 3.3 GHz and 3.6 GHz respectively on the E-plane xoz plane;

[0026] Fig. 9 The normalized radiation patterns of the horizontally polarized element in the embodiment of the present invention operating at 2 GHz, 2.7 GHz, 3.3 GHz and 3.6 GHz respectively on the H-plane xoy plane;

[0027] Fig.10 They are respectively the impedance matching coefficients of the vertical polarization element when the metal ground radius is expanded from 90 mm to 150 mm and 200 mm in the embodiment of the present invention. 11 | Frequency variation curve and impedance matching coefficient of horizontal polarization element|S 22 |Graph showing changes with frequency. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] Reference Figure 1 and Figure 2 The present invention includes a horizontally polarized radiator 1, a metal coupling patch 2, a vertically polarized radiator 3 and a metal floor 4 which are arranged in sequence from top to bottom; the horizontally polarized radiator 1 includes a dielectric substrate 11 and horizontally polarized radiating patches 12 and a feeding network 13 printed on the upper and lower surfaces thereof; the metal coupling patch 2 includes a metal disk 21 and a metal ring 22 nested on its circumference; the horizontally polarized radiating patch 12 is connected to the metal disk 21 through a first short-circuit line 5, and the metal ring 22 and the horizontally polarized radiating patch 12 are connected to the metal floor 4 through four second short-circuit lines 6 and four third short-circuit lines 7, respectively.

[0030] The cross section of the dielectric substrate 11 is circular, with a thickness of 1 mm. The material is Arlon AD255A, with a relative dielectric constant of 2.55 and a loss tangent of 0.0015. The horizontally polarized radiator is excited by an external 50Ω coaxial line through a feeding network 13. The metal disk 21 provides a connection between the first short-circuit line 5 and the horizontally polarized radiation patch 12, the metal ring 22 provides a connection between the second short-circuit line 6 and the metal floor 4, and the annular gap in the middle provides capacitive loading, which can improve the impedance matching of the vertically polarized element.

[0031] The vertically polarized radiator 3 is excited by a 50Ω coaxial line externally connected to the lower surface. The metal coupling patch 2 and the second short-circuit line 6 act on the vertically polarized radiator 3, and are used as capacitive loading and inductive loading respectively. The working principle is that when the vertically polarized radiator is working, the current on the surface of the radiator 3 will be coupled to the metal coupling patch 2, and conducted to the metal floor 4 by the second short-circuit line 6, thereby increasing the electrical length of the antenna, thereby widening the bandwidth of the vertically polarized radiator. The first short-circuit line 5 connects the center of the metal disk 21 with the center of the upper horizontally polarized radiating patch 12, and the third short-circuit line 7 connects the upper horizontally polarized radiating patch 12 with the metal floor 4 through a microstrip line 123. This connection makes the horizontally polarized radiating patch the top load of the vertically polarized radiator. The working principle is that when the vertically polarized radiator is working, the surface current of the radiator 3 is coupled to the metal coupling patch 2, and further conducted to the horizontally polarized radiating patch 12 by the first short-circuit loading 5, and then conducted back to the metal floor 4 by the third short-circuit line 7, which can also increase the electrical length of the antenna and widen the bandwidth. The radiator 3 is an inverted cone structure with an internal vacuum, that is, a metal shell that is circular in top view and isosceles trapezoidal in side view. When the vertically polarized radiator 3 is working, the current is concentrated on the outer surface of the radiator, so that the vertically polarized radiator has good omnidirectionality.

[0032] Reference Figure 3 The horizontally polarized radiation patch 12 comprises a circular patch 121 and four dipole antenna units 122 and a microstrip line 123 connected thereto and symmetrically distributed at the center thereof. The microstrip line 123 extends to the circumferential edge of the dielectric substrate 11 in order to connect the horizontally polarized radiation patch 12 with the third short-circuit line 7; four first rectangular slots 124 are etched on the circular patch 121, and their function is to improve the high-frequency radiation pattern of the horizontally polarized radiator; the dipole antenna unit 122 adopts a quasi-T-shaped structure with an arc-shaped transverse arm, a rectangular notch is etched in the middle of the transverse arm, and a second rectangular slot 124 is etched on the longitudinal arm. 5. A third rectangular slot 126 is etched between the second rectangular slot 125 and the bottom of the rectangular notch. The third rectangular slot 126 connects the second rectangular slot and the rectangular notch and is used for the feeding network 13 to perform microstrip-slot coupling feeding on the horizontally polarized radiation patch 12. The width of the second rectangular slot 125 is greater than the width of the third rectangular slot 126, and its function is to act as a resonator to improve the impedance matching of the horizontally polarized element. The center of the four dipole antenna units 122 is close to the edge of the circumference of the dielectric substrate 11, and an arc-shaped director 127 is printed on each of the edges to improve the impedance matching of the horizontally polarized element.

[0033] Reference Figure 4The feeding network 13 adopts a one-to-four power divider. The feeding network 13 is composed of a 50Ω microstrip line, an 88Ω microstrip line, a 110Ω microstrip line, a 100Ω microstrip line and a reverse extension branch 132. The feeding starts from the input terminal 131, and the distance and impedance to each third rectangular slot 126 are the same, so that currents of equal amplitude and phase flow through each radiating element 122, thereby achieving good omnidirectionality. The parasitic structure 8 is located between the projections of two adjacent radiating elements 122, and the line thereof coincides with the microstrip line 123, and its function is to improve the impedance matching of the horizontally polarized element.

[0034] The following is a further description of the technical effects of the present invention in conjunction with simulation experiments:

[0035] 1. Experimental conditions and contents:

[0036] The simulation software ANSYS Electronics Desktop v.18.2 is used to simulate the electrical characteristics of the present invention, including the impedance matching coefficient of the vertically polarized radiator before and after loading the microstrip line and the short-circuit line|S 11 |、Impedance matching coefficient of horizontal polarization radiator before and after loading microstrip line and short circuit|S 22 | and the isolation between horizontally polarized radiators and vertically polarized radiators |S 21 The curve relationship diagram of | with frequency, the normalized radiation patterns of the E-plane xoz and H-plane xoy of the vertically polarized radiator and the horizontally polarized radiator working at frequencies of 2GHz, 2.7GHz, 3.3GHz, and 3.6GHz under the final model, and the simulation results of |S11| and |S22| after the size of the metal floor changes are shown in the figure. Figure 5-10 shown.

[0037] 2. Experimental results analysis:

[0038] Reference Figure 5 , the antenna impedance matching coefficient in the frequency range of 1.6GHz-3.7GHz |S 11 |≤-10dB, impedance matching coefficient in the frequency range of 1.95GHz-3.67GHz|S 22 |≤-10dB, the isolation in the whole frequency band is higher than 20dB. At the same time, it can be seen that before the microstrip line and short-circuit line are introduced, the impedance matching coefficient of the antenna between 2.4GHz and 3.0GHz is |S 11 |>-10dB, and before and after the introduction of microstrip line and short-circuit line, |S 22|The change is not large, which shows that the introduction of the strip line completely improves the impedance matching of the vertically polarized radiator and has no side effect on the impedance matching of the horizontally polarized radiator. After the introduction of the microstrip line and the short-circuit line, the vertically polarized radiator bandwidth of the dual-polarized antenna is 1.6GHz-3.7GHz (79.2%), and the horizontally polarized radiator bandwidth is 1.95GHz-3.67GHz (60.9%).

[0039] Reference Figure 6-7 , Figure 6 (a) is the E-plane xoz radiation pattern of the vertically polarized radiator working at the frequency of 2 GHz and 2.7 GHz. Figure 6 (b) is the E-plane xoz radiation pattern of the vertically polarized radiator working at frequencies of 3.3 GHz and 3.6 GHz; Figure 7 (a) is the H-plane xoy radiation pattern of the vertically polarized radiator working at the frequency of 2 GHz and 2.7 GHz. Figure 7 (b) is the H-plane xoy-plane radiation pattern of the vertically polarized radiator working at frequencies of 3.3 GHz and 3.6 GHz. At frequencies of 2 GHz, 2.7 GHz, 3.3 GHz, and 3.6 GHz, the non-uniformity of the normalized radiation pattern of the H-plane xoy-plane of the vertically polarized radiator is less than 4 dB, and the maximum gain of the normalized radiation pattern of the E-plane xoz-plane varies between 4.2 dBi and 6.8 dBi, with a maximum gain of 6.8 dBi.

[0040] Reference Figure 8-9 , Figure 8 (a) is the E-plane xoz radiation pattern of a horizontally polarized radiator operating at frequencies of 2 GHz and 2.7 GHz. Figure 8 (b) is the E-plane xoz radiation pattern of the horizontally polarized radiator working at frequencies of 3.3 GHz and 3.6 GHz; Fig. 9 (a) is the H-plane xoy radiation pattern of the horizontally polarized radiator working at the frequency of 2 GHz and 2.7 GHz. Fig. 9 (b) is the H-plane xoy-plane radiation pattern of the horizontally polarized radiator working at frequencies of 3.3 GHz and 3.6 GHz. At frequencies of 2 GHz, 2.7 GHz, 3.3 GHz, and 3.6 GHz, the non-uniformity of the normalized radiation pattern of the H-plane xoy-plane of the horizontally polarized radiator is less than 5 dB, and the maximum gain of the normalized radiation pattern of the E-plane xoz-plane varies between 4.8 dBi and 7.0 dBi, with a maximum gain of 7.0 dBi.

[0041] Reference Fig.10 , Fig.10 (a) The impedance matching coefficient of the vertically polarized radiator after the metal ground radius is expanded from the original 90 mm to 150 mm and 200 mm | S 11 |Graph of changes with frequency, Fig.10 (b) The impedance matching coefficient of the horizontally polarized radiator after the metal ground radius is expanded from the original 90 mm to 150 mm and 200 mm | S 22 |The curve graph of the change with frequency. It can be seen that after the metal ground radius is expanded from the original 90mm to 150mm and 200mm in the present invention, the impedance matching coefficient of the vertical polarization radiator and the horizontal polarization radiator |S 11 |、|S 22 The frequency variation curve is basically consistent with the original simulation result. It can be concluded that the antenna of the present invention has good tolerance for the problem of changes in the antenna installation environment.

Claims

1. A broadband low-profile dual-polarization omnidirectional antenna, comprising a horizontally polarized radiator (1), a metal coupling patch (2), a vertically polarized radiator (3) and a metal floor (4) arranged in sequence from top to bottom; the horizontally polarized radiator (1) comprises a dielectric substrate (11) and horizontally polarized radiating patches (12) printed on the upper and lower surfaces thereof, and a feeding network (13); the metal coupling patch (2) comprises a metal disk (21) and a metal ring (22) nested on the circumference thereof; characterized in that: The horizontally polarized radiation patch (12) and the metal disk (21) are connected via a first short-circuit line (5), and the metal ring (22) and the horizontally polarized radiation patch (12) are connected to the metal floor (4) via four second short-circuit lines (6) and four third short-circuit lines (7), respectively.

2. The broadband low-profile dual-polarization omnidirectional antenna according to claim 1, characterized in that: The dielectric substrate (11) and the metal floor (4) both have circular plate shapes, and the center normals of the dielectric substrate (11), the metal floor (4) and the metal coupling patch (2) coincide with each other.

3. The broadband low-profile dual-polarization omnidirectional antenna according to claim 2, characterized in that: The horizontally polarized radiation patch (12) comprises a circular patch (121) and four dipole antenna units (122) and a microstrip line (123) connected thereto and symmetrically distributed at the center; four first rectangular slots (124) are etched on the circular patch (121); the dipole antenna unit (122) adopts a quasi-T-shaped structure with an arc-shaped transverse arm, a rectangular notch is etched in the middle of the transverse arm, a second rectangular slot (125) is etched on the longitudinal arm, and a third rectangular slot (126) is etched between the second rectangular slot (125) and the bottom of the rectangular notch; and an arc-shaped director (127) is printed on the edges of the center of the four dipole antenna units (122) close to the circumference of the dielectric substrate (11).

4. The broadband low-profile dual-polarization omnidirectional antenna according to claim 3, characterized in that: The dielectric substrate (11) has four arc-shaped parasitic patches (8) printed on its lower surface, and the four arc-shaped parasitic patches respectively intersect with the projections of the four microstrip lines (123).

5. The broadband low-profile dual-polarization omnidirectional antenna according to claim 3, characterized in that: The horizontally polarized radiation patch (12) comprises four centrosymmetrically distributed microstrip lines (123) on a circular patch (121) which are respectively located on the angular bisectors between adjacent dipole antenna units (122).

6. The broadband low-profile dual-polarization omnidirectional antenna according to claim 3, characterized in that: The four microstrip lines (123) distributed symmetrically around the center are connected to the metal floor (4) via four third short-circuit lines (7) respectively.

7. The broadband low-profile dual-polarization omnidirectional antenna according to claim 3, characterized in that: The center of the horizontally polarized radiation patch (12) is located on the center normal line of the dielectric substrate (11).

8. The broadband low-profile dual-polarization omnidirectional antenna according to claim 3, characterized in that: The feeding network (13) adopts a one-to-four power divider, wherein the input port (131) is connected to an external coaxial line, and the ends of the four output ports are respectively connected to a reverse extension branch (132), and the four output ports respectively realize coupling feeding to the horizontally polarized radiation patch (12) through the third rectangular slots (126) etched on the four dipole antenna units (122).

9. The broadband low-profile dual-polarization omnidirectional antenna according to claim 1, characterized in that: The centers of the metal disk (21) and the metal ring (22) of the metal coupling patch (2) are both located on the central axis of the vertically polarized radiator (3).

10. The broadband low-profile dual-polarization omnidirectional antenna according to claim 1, characterized in that: The vertically polarized radiator (3) adopts a hollow inverted disk-cone structure, and the diameter of the disk-cone bottom is smaller than the diameter of the metal ring (22).

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