A broadband low-coupling dual-polarized antenna with a unique U-shaped slot structure

Abstract

The application discloses a broadband low-coupling dual-polarized antenna with a unique U-shaped groove structure, belongs to the microwave technical field, and comprises a square metal floor 1, two coaxial lines 4, a dielectric substrate 2, a circular metal sheet 3 and nylon columns 5 and 6 used for being fixedly connected from bottom to top, two cross-placed dipoles are printed on the upper and lower surfaces of the dielectric substrate 2, each dipole has two dipole arms 7 printed on the upper and lower surfaces of the dielectric substrate 2 respectively, and the four dipole arms 7 are of the same structure. The dipole arm 7 is provided with a unique U-shaped groove structure 8, two high-frequency resonance frequency points can be introduced for the antenna, and the impedance bandwidth of the antenna is widened; the circular metal sheet 3 is very close to the dielectric substrate 2 directly above and is tightly coupled with the two dipoles, so that the impedance matching in the working frequency band of the antenna can be improved, the antenna has the excellent characteristics of low bandwidth and high coupling, and the structure is simple and easy to be applied to MIMO antennas.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and in particular relates to a broadband low-coupling dual-polarization antenna with a unique U-shaped groove structure. Background Art

[0002] Dual-polarized antennas can simultaneously generate two orthogonal electromagnetic waves. Therefore, they can significantly increase communication capacity without increasing bandwidth and reduce the number of antennas required. Consequently, dual-polarized antennas have been widely used and developed. Currently, with the continuous development of wireless communication technology, more and more spectrum resources are being utilized. Antenna design often requires antennas that can simultaneously meet multiple operating frequency bands. Therefore, multi-band antennas and broadband antennas are often the preferred designs.

[0003] Cross-dipole antennas, patch antennas, and magneto-electric dipole antennas are often used to implement dual-polarized antennas. While cross-dipole antennas are relatively mature and have many applications, there are still relatively few examples of achieving broadband, low-coupling cross-dipole antennas. Summary of the Invention

[0004] The present invention aims to realize a broadband low-coupling dual-polarization antenna, which can be applied to base station antennas and MIMO antennas. The antenna can realize dual linear polarization, and its main advantages are low coupling and wide bandwidth.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A broadband low-coupling dual-polarization antenna with a unique U-shaped slot structure comprises a square metal floor, two feeding coaxial lines, a dielectric substrate, a circular metal sheet, and a nylon column for fixing.

[0007] The square metal floor is a thin square metal sheet with two circular through holes in the middle for the two feeding coaxial lines to contact and pass through.

[0008] The dielectric substrate is fixed directly above the square metal floor via nylon posts, with the distance between them within a quarter of the free-space wavelength corresponding to the antenna's operating frequency band. Two crossed dipoles are printed on the upper and lower surfaces of the dielectric substrate. The printed material is metal. The two dipoles can operate simultaneously and independently, and the polarizations of the electromagnetic waves radiated by them are orthogonal. The two dipole arms of each dipole are printed on the upper and lower surfaces of the dielectric substrate, respectively. Two coaxial lines that contact and pass through the square metal floor extend to the dielectric substrate. The outer metal layer of the coaxial line is connected to the dipole arm printed on the lower surface of the dielectric substrate and extends thereto. The inner metal cylinder of the coaxial line passes through the dielectric substrate and extends to the upper surface of the dielectric substrate. It is connected to the other dipole arm of the dipole via a metal strip printed on the surface of the dielectric substrate. To prevent the two metal strips from contacting each other, one metal strip is passed through a metal through-hole to the lower surface of the dielectric substrate, thereby bypassing the other metal strip.

[0009] The circular metal sheet is located directly above the dielectric substrate. The circular metal sheet is very close to the dielectric substrate and is tightly coupled with the two dipoles to work together. There are four identical circular holes around the circular metal sheet, and the nylon columns are fixed to the dielectric substrate through the circular holes.

[0010] The two dipoles have the same structure, and the two dipole arms of each dipole also have the same structure. The dipole arms are a combination of an isosceles right triangle, a large rectangle, and two small rectangles. The base of the isosceles right triangle coincides with the width of the large rectangle, and the two small rectangles are located on the side of the large rectangle away from the isosceles right triangle and coincide with the long sides of the large rectangle along the corners. All four dipole arms have the same unique U-shaped slot structure. The slot is U-shaped overall, with two small rectangular sections extending outward near the U-shaped opening. This unique U-shaped slot structure provides the antenna with two high-frequency resonant frequencies, widening the antenna's impedance bandwidth.

[0011] The circular metal sheet on the dielectric substrate can improve the impedance matching characteristics of the antenna.

[0012] By adjusting the distance between the dipole arms, the resonance position and resonance depth of the low-frequency resonance frequency point can be changed, and the depth of the high-frequency resonance frequency point can be changed.

[0013] By adjusting the length of the dipole arm, the positions of the three resonant frequencies can be changed.

[0014] The antenna is fed by two coaxial cables and the input impedance of the port is 50 ohms.

[0015] The beneficial effects of the present invention are:

[0016] (1) The present invention uses two crossed dipoles placed orthogonally. A dipole itself has a resonant frequency point. The two dipoles are placed orthogonally and coupled with each other. The unique U-shaped groove structure on the dipole arms cooperates with each other to generate two additional higher frequency resonant frequencies, thereby widening the bandwidth of the antenna.

[0017] (2) The circular metal sheet of the present invention does not change the resonant mode of the antenna, but improves the impedance matching within the frequency band. The circular metal sheet is a thin metal sheet with a reserved mounting hole and a simple structure.

[0018] (3) The coaxial line and the metal strips on the upper and lower surfaces of the dielectric substrate of the present invention serve as a feeder, and have a simple structure and good stability.

[0019] (4) The working frequency bandwidth of the antenna described in the present invention can reach more than 60% relative to the working bandwidth.

[0020] (5) The antenna described in the present invention has high isolation, and the isolation between the two polarization ports can reach more than 30dB within the working frequency band.

[0021] (6) The antenna structure of the present invention is simple and can be easily applied to base station antennas and MIMO antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a broadband low-coupling dual-polarization antenna with a unique U-shaped slot structure according to an embodiment of the present invention;

[0023] Figure 2 for Figure 1 Side view of the middle antenna;

[0024] Figure 3 for Figure 2 A top view of the upper surface of the dielectric substrate;

[0025] Figure 4 for Figure 2 A top view of the lower surface of the dielectric substrate;

[0026] Figure 5 for Figure 2 A top view of the medium circular metal piece;

[0027] Figure 6 for Figure 1 Schematic diagram of the metal strip and metal through-hole structure used to connect the dipoles in the middle of the dipole;

[0028] Figure 7 Schematic diagram of the S parameters of the antenna described in the embodiment;

[0029] Figure 8The radiation pattern of the antenna of the embodiment at a frequency of 440 MHz, wherein (a) is the E plane; (b) is the H plane;

[0030] Figure 9 The radiation pattern of the antenna of the embodiment at a frequency of 830 MHz, wherein (a) is the E plane; (b) is the H plane;

[0031] Figure 10 Schematic diagram of the gain of the antenna described in the embodiment; DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0033] This embodiment provides a broadband low-coupling dual-polarization antenna with a unique U-shaped slot structure. Figure 1 As shown, the side view is Figure 2 As shown, it includes three layers from bottom to top: a square metal floor 1, two coaxial lines 4, a dielectric substrate 2 and a circular metal sheet 3, and also multiple nylon columns 5 and 6 for fixation. The square metal floor is a square metal plate with two through-holes in the middle for the coaxial line 4 to contact and pass through. The dielectric substrate 2 is fixed to the square metal floor 1 by four nylon posts 5. Two cross-shaped dipoles are printed on the upper and lower surfaces of the dielectric substrate 2. Each dipole consists of two dipole arms 7, a metal strip 9 for connecting the two dipole arms 7 to the power supply, and a metal through-hole 10. The four dipole arms 7 are identical in shape. The two dipole arms 7 of each dipole are printed on the upper and lower surfaces of the dielectric substrate 2. The coaxial line 4 extends from the square metal floor 1 to the dielectric substrate 2. The outer conductor of the coaxial line 4 is connected to the dipole arm 7 printed on the lower surface of the dielectric substrate 2. The inner conductor passes through the dielectric substrate 2 and is connected to the other dipole arm of the dipole via the metal strip 9 printed on the upper surface of the dielectric substrate 2. To prevent the two metal strips 9 from contacting each other, one metal strip 9 is passed through the metal through-hole 10 to the lower surface of the dielectric substrate 2, thereby bypassing the other metal strip 9. The top view of the dielectric substrate 2 is as follows Figure 3As shown, the upper surface of the dielectric substrate 2 is printed with two dipole arms 7, each belonging to two crossed dipoles. The gap between two adjacent dipole arms 7 is 4.1 mm. The outer shape of the dipole arms 7 is a combination of an isosceles right triangle, a large rectangle, and two small rectangles. The width of the large rectangle coincides with the base of the isosceles right triangle, and the two small rectangles coincide with the long sides of the large rectangle along the corners of the large rectangle on the side away from the isosceles right triangle. The interior of the dipole arm has been removed to form a unique U-shaped groove structure 8. The unique U-shaped groove structure 8 is U-shaped, with two small rectangles extending outward near the U-shaped opening. The U-shape consists of a semicircle and a rectangle whose wide side coincides with the diameter of the semicircle. A top view of the lower surface of the dielectric substrate 2 is shown in FIG. Figure 4 As shown, two other dipole arms 7 corresponding to the dipole arms on the upper surface of the dielectric substrate 2 are printed on the lower surface of the dielectric substrate 2, and metal strips 9 for connecting the dipole arms are also printed on the lower surface of the dielectric substrate. Figure 6 As shown in FIG, the metal strips 9 and metal through holes 10 for connecting the dipole arms on the upper and lower surfaces of the dielectric substrate are shown in detail. Figure 5 As shown, it is a circular metal sheet with four through holes around the circular metal sheet 3. Four nylon columns 6 fix the circular metal sheet 3 on the dielectric substrate 2 through the four through holes.

[0034] The square metal floor 1 measures 375 mm x 375 mm, and the distance between the square metal floor 1 and the dielectric substrate 2 is 156 mm. The dielectric substrate 2 is made of Rogers RO4003, with a relative permittivity of 3.55, a loss tangent of 0.0027, and a thickness of 1.524 mm. The dielectric substrate 2 measures 240 mm x 240 mm. The base of the isosceles right triangle in the dipole arm 7 is 81 mm long, the same as the width of the large rectangle. The large rectangle is 70 mm long. The unique U-shaped groove structure 8 in the dipole arm 7 consists of two small rectangles: a semicircle and a large rectangle. The diameter of the semicircle is 60 mm, the same as the width of the large rectangle. The large rectangle is 44 mm long. The two small rectangles extend outward 4 mm from the U-shaped opening. The small rectangles measure 23 mm x 6 mm. The center of the semicircle is 60 mm from the center of the dipole. The circular metal piece 3 is 5 mm above the dielectric substrate 2 . The thickness of the circular metal piece 3 is 2 mm and the diameter is 81 mm.

[0035] The size of the antenna in this embodiment is 0.4λ0×0.4λ0×0.28λ0 (λ0 is the free space wavelength corresponding to 500MHz), and the S parameter simulation results are as follows: Figure 7As shown in the figure, there are three resonant frequencies. The lowest resonant frequency is the dipole itself without the unique U-shaped slot structure. The two high-frequency resonant frequencies are introduced by the unique U-shaped slot structure. Its operating frequency band is: 440MHz-830MHz (relative bandwidth is 61.4%), and the isolation within the operating frequency band is better than 28dB. The radiation patterns of the antenna at 440MHz and 830MHz are shown as follows: Figure 8 、 Figure 9 As shown in the figure, it can be seen that the cross-polarization ratio of the E-plane and the H-plane is better than 20dB. The gain diagram of the antenna is as follows Figure 10 shown.

[0036] The broadband, low-coupling, dual-polarized antenna with a unique U-shaped slot structure described in this embodiment has two cross-placed dipoles, each generating two orthogonally polarized electromagnetic waves that operate independently. The distance between the square metal floor and the dipoles on the dielectric substrate is within a quarter of the air wavelength corresponding to the operating frequency band. The electromagnetic waves generated by the dipoles radiate outward. The downward-radiating electromagnetic waves reflect off the square metal floor, undergoing a 180° phase shift. The two quarter-wavelengths they travel over are superimposed on the upward-radiating electromagnetic waves, which are then radiated in phase. The unique U-shaped slot structure in the dipole arms of the broadband, low-coupling, dual-polarized antenna with a unique U-shaped slot structure described in this embodiment provides the antenna with two high-frequency resonant frequencies. Combined with the dipole's existing low-frequency resonant frequency band, this widens the antenna's impedance bandwidth. The circular metal plate improves impedance matching within the operating frequency band. Without the circular metal plate, the impedance matching within the band can only reach |S11| < -10dB.

[0037] The dual-polarized antenna described in this embodiment has high isolation and broadband characteristics, and is also small in size and simple in structure, and can be applied to base station antennas and MIMO antennas.

[0038] The above descriptions are only preferred embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making any creative work should fall within the scope of protection of the present invention.

Claims

1. A broadband low-coupling cross-dipole antenna with a unique U-shaped slot structure, characterized in that: It includes a square metal floor arranged from bottom to top, two coaxial lines for feeding, a dielectric substrate, a circular metal sheet and a plurality of nylon columns for fixing; The square metal floor is a thin metal sheet with two circular through holes in the middle thereof, and the two coaxial lines pass through and contact the two circular through holes; The dielectric substrate is fixed above the metal floor via nylon support columns, with the spacing between them being within a quarter of the free-space wavelength corresponding to the operating frequency band of the cross-dipole antenna. Two metal dipoles are printed on the upper and lower surfaces of the dielectric substrate, and the two arms of the dipole are printed on the upper and lower surfaces of the dielectric substrate, respectively. Two coaxial lines extend to the dielectric substrate, with the outer metal layer of the coaxial lines extending to and contacting one dipole arm on the lower surface of the dielectric substrate. The inner metal cylinder of the coaxial line passes through the dielectric substrate and extends to the upper surface of the dielectric substrate, and is connected to the other dipole arm of the dipole via a metal strip on the surface of the dielectric substrate. The circular metal sheet is located above the dielectric substrate. The circular metal sheet and the two dipoles are tightly coupled to each other. There are circular holes around the circular metal sheet, and the circular metal sheet is fixed to the circular holes on the dielectric substrate by nylon columns. The four dipole arms are provided with a unique U-shaped groove structure. The U-shaped mouth of the unique U-shaped groove structure is set outward, and rectangular grooves extending outward are formed on both sides of the U-shaped mouth. The unique U-shaped groove structure consists of a semicircle and a large rectangle, two small rectangles. The diameter of the semicircle is the same as the length of the large rectangle, which is 60mm. The width of the large rectangle is 44mm. The large rectangle is on the opening side of the semicircle, and the two small rectangles are 4mm away from the U-shaped mouth. The length and width of the small rectangle are 23mm×6mm. The center of the semicircle is 60mm away from the center of the dipole. The unique U-shaped groove structure provides two high-frequency resonant frequency points for the cross-dipole antenna, widening its impedance bandwidth.

2. The broadband low-coupling cross-dipole antenna with a unique U-shaped groove structure according to claim 1, characterized in that: The two dipoles are placed crosswise and orthogonally, and can work independently at the same time, and the polarization of the electromagnetic waves radiated by them are orthogonal.

3. The broadband low-coupling cross-dipole antenna with a unique U-shaped groove structure according to claim 1, characterized in that: The two dipoles have the same structure, with a triangular structure at the center and a rectangular structure at the outer edge of the dipole arm.

4. The broadband low-coupling cross-dipole antenna with a unique U-shaped groove structure according to claim 1, characterized in that: By adjusting the distance between the dipole arms, the resonance position and resonance depth of the low-frequency resonance frequency point can be changed, and the depth of the second resonance frequency point can be changed.

5. The broadband low-coupling cross-dipole antenna with a unique U-shaped groove structure according to claim 1, characterized in that: By adjusting the length of the dipole arms, the positions of the two resonant frequencies can be changed.

6. The broadband low-coupling cross-dipole antenna with a unique U-shaped groove structure according to claim 1, characterized in that: Two coaxial cables are used for feeding, and the input impedance of the port is 50 ohms.

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