A sub-wavelength patch based dual-polarized metasurface antenna

Abstract

The application discloses a kind of bipolarization metasurface antennas based on subwavelength patch, belong to wireless communication technical field from bottom to top sequentially layering setting coaxial probe, metal floor, balanced feed balun, metal feed line, dielectric substrate and subwavelength grid patch;Two balanced feed baluns are perpendicular to each other, and are vertically placed on the metal floor;Metal feed line is composed of four L-shaped feed lines, to make the current in vertical direction and horizontal direction pass through vector superposition and form the current of ±45 ° direction;Subwavelength grid patch is composed of twenty-five small patches with 5x5 array;Dielectric substrate is placed on balanced feed balun, subwavelength grid patch is printed on the upper surface of dielectric substrate, and metal feed line is printed on the lower surface of dielectric substrate 5;The profile height of the metasurface antenna of the application is 8.4mm, and the antenna can work at 3.4-4.1GHz, and has stable radiation performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless communication, and specifically provides a dual-polarized metasurface antenna based on a subwavelength patch, which is used to simultaneously meet the demand of low profile and wideband of a base station antenna. BACKGROUND

[0002] Modern communication systems need a large number of base station antennas to expand the communication capacity and realize high-speed signal transmission. Such a demand for multiple antennas brings challenges to the design of space-limited base stations. In order to save the space of the base station, the base station antenna uses the structure of the frequency selective surface and the low scattering technology to realize the multi-band antenna sharing the radiation aperture. However, in the multi-frequency shared aperture base station antenna, the antennas of different frequency bands are coupled with each other, which causes the deterioration of the performance of the base station. In the complex electromagnetic environment of the shared aperture antenna array, the methods and measures for suppressing the coupling are very limited. Among them, reducing the antenna profile to increase the height difference between the antennas of different frequency bands is an important method for suppressing the antenna coupling. Therefore, the low profile base station antenna has great application potential for future communication systems. The low profile base station antenna is mostly in the form of a microstrip patch antenna. However, the narrow bandwidth of the microstrip patch antenna limits the application of the microstrip antenna in the base station antenna. In recent years, a large number of single-polarized metasurface antennas have been studied. These single-polarized metasurface antennas have the advantages of low profile, wide frequency band and high gain. However, due to the limitation of single polarization and back radiation, these metasurface antennas cannot be applied to the fifth generation communication base station. In view of this, it is necessary to propose a low profile wideband dual-polarized metasurface antenna to meet the development needs of the communication base station. SUMMARY

[0003] The application aims to provide a dual-polarized metasurface antenna based on a subwavelength patch, which solves the technical problems of the narrow bandwidth of the traditional low profile base station antenna and the difficulty in realizing ±45° dual polarization.

[0004] The technical scheme adopted by the application to solve the technical problems is as follows:

[0005] A dual-polarized metasurface antenna based on a subwavelength patch, comprising coaxial probes 1, a metal ground plate 2, balanced feed baluns 3, metal feed lines 4, a dielectric substrate 5 and subwavelength grid patches 6 which are sequentially stacked from bottom to top;

[0006] The two balanced feed baluns 3 are vertically crossed and vertically placed on the metal ground plate 2; each balanced feed balun is composed of a feed line 3-1 and a balun ground plate 3-2; the feed line 3-1 is connected with the inner core of the coaxial probe 1, and the lower edge of the balun ground plate is connected with the ground plate and the upper edge is connected with the metal feed line 4; at the same time, one of the balanced feed baluns adopts a feed line bridge structure 3-3, and the feed line is bent downward by a part, so that both feed lines can work normally after the two balanced feed baluns 3 are vertically crossed;

[0007] The metal feeding line 4 is composed of four L-shaped feeding lines, each of which is composed of a metal wire 4-1, a metal wire 4-2 and a metal junction 4-3; the currents in the vertical direction and the horizontal direction are superimposed to form currents in the ±45° direction;

[0008] The subwavelength grid patch 6 is composed of twenty-five small patches arranged in a 5x5 array;

[0009] The medium substrate 5 is placed on the balanced feeding balun 3, the subwavelength grid patch 6 is printed on the upper surface of the medium substrate 5, and the metal feeding line 4 is printed on the lower surface of the medium substrate 5;

[0010] The current is fed to the balun 3 through the coaxial probe 1; the current is fed to the metal feeding line 4 through the balun ground plate 3-2, and then the energy is coupled to the subwavelength grid patch 6 by the metal feeding line 4, and finally the energy is radiated outward in the form of electromagnetic waves by the subwavelength grid patch 6.

[0011] Further, the medium substrate adopts FR4 with a thickness of 1mm, a relative dielectric constant of 4.4 and a loss tangent value of 0.02.

[0012] Further, the profile height of the metasurface antenna is 8.4mm.

[0013] Further, the metasurface antenna can work at 3.4-4.1GHz.

[0014] The application has the beneficial effects that:

[0015] The application provides a dual-polarized metasurface antenna based on a subwavelength patch, which has the advantages of low profile, wide bandwidth and stable radiation.

[0016] 1. The balanced balun feeding 3 of the application replaces the traditional slot feeding structure of the metasurface antenna, solving the problem of back radiation of the slot feeding damaging the back radio frequency circuit.

[0017] 2. The metal feeding line 4 of the application adopts an L-shaped metal structure, so that the currents in the vertical direction and the horizontal direction are superimposed to form currents in the ±45° direction, realizing ±45° polarized radiation of the metasurface antenna.

[0018] 3. Compared with the base station microstrip patch antenna, the subwavelength grid patch 6 of the application replaces the microstrip patch, widens the antenna bandwidth and meets the demand of the base station for low profile and wide bandwidth.

[0019] 4. The profile height of the metasurface antenna of the application is 8.4mm, the antenna can work at 3.4-4.1GHz, and has stable radiation performance.

[0020] 5、The bipolarized metasurface antenna has the advantages of low profile, wide bandwidth and stable radiation, and has great application value for communication base stations. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A three-dimensional schematic view of the bipolarized metasurface antenna based on a subwavelength grid patch provided by the present application is shown in the exploded view.

[0022] Figure 2 A sectional view of the bipolarized metasurface antenna based on a subwavelength grid patch provided by the present application is shown in the schematic view.

[0023] Figure 3 A balanced feed balun 3 structure schematic diagram of the bipolarized metasurface antenna based on a subwavelength grid patch provided by the present application is shown in the exploded view.

[0024] Figure 4 A metal feed line 4 structure schematic diagram of the bipolarized metasurface antenna based on a subwavelength grid patch provided by the present application is shown in the exploded view.

[0025] Figure 5 A subwavelength grid patch 6 structure schematic diagram of the bipolarized metasurface antenna based on a subwavelength grid patch provided by the present application is shown in the exploded view.

[0026] Figure 6 Port S parameter diagrams (S11, S22 and S21) of the bipolarized metasurface antenna based on a subwavelength grid patch in the embodiment of the present application are shown in the exploded view.

[0027] Figure 7 Horizontal patterns of the bipolarized metasurface antenna based on a subwavelength grid patch in the embodiment of the present application working at 3.4 GHz, 3.7 GHz, 3.9 GHz and 4.1 GHz are shown in the exploded view.

[0028] Wherein: 1-coaxial probe, 2-metal floor, 3-balanced feed balun, 4-metal feed line, 5-dielectric substrate, 6-subwavelength grid patch, 4-1-metal line, 4-2-metal line and 4-3-metal connection 3-1-feed line, 3-2-balun ground plate, 3-3-feed line bridge structure DETAILED DESCRIPTION

[0029] The present application will be described in detail below in conjunction with the drawings and specific embodiments, but the scope of protection of the present application is not limited to the following embodiments, and should include all contents in the claims. Moreover, those skilled in the art can realize all contents in the claims from the following one embodiment.

[0030] The specific implementation process is as follows:

[0031] The present embodiment provides a bipolarized metasurface antenna based on a subwavelength patch, and the structure is as followsFigures 1-5 As shown, specifically comprises: coaxial probe 1, metal floor 2, balanced feed balun 3, metal feed line 4, dielectric substrate 5 and subwavelength grid patch 6 are sequentially stacked from bottom to top; Specifically:

[0032] Two balanced feed baluns 3 are perpendicular to each other and vertically placed on the metal floor 2; The balun printed dielectric substrate adopts FR4 with a thickness of 1mm, a relative dielectric constant of 4.4 and a loss tangent value of 0.02; Each balanced feed balun is composed of a feed line 3-1 and a balun ground plate 3-2, wherein the feed line 3-1 is connected with the inner core of the coaxial probe, and the lower edge of the balun ground plate is connected with the floor and the upper edge is connected with the metal feed line 4; In order to avoid the cross connection of the two feed lines, the application adopts a feed line bridge structure 3-3, one of which is designed to be bent downward for a part, so that both feed lines can work normally;

[0033] The metal feed line 4 is composed of four L-shaped feed lines, each of which is composed of a metal wire 4-1, a metal wire 4-2 and a metal connection 4-3; The metal connection 4-3 is connected with the balun ground plate 3-2, and the current is fed to the metal connection 4-3 through the balun first, and then transmitted to the metal wires 4-1 and 4-2 in parallel; The structure of the feed line 4 determines the ±45° polarization performance of the antenna, and the current distribution of the metal feed line 4 is taken as an example to illustrate the +45° polarization, the metal wire 4-1 has upward and downward current distribution, and the metal wire 4-3 has right and left current distribution at the same time, according to the principle of proper superposition of current, the metal wire 4 forms +45° polarization current;

[0034] The subwavelength grid patch 6 is composed of twenty-five small patches in a 5x5 array; The size of the small patch is the corresponding subwavelength of the working center frequency point; The dielectric substrate 5 is placed on the balanced feed balun 3, the subwavelength grid patch 6 is printed on the upper surface of the dielectric substrate 5, and the metal feed line 4 is printed on the lower surface of the dielectric substrate 5; The dielectric substrate 5 adopts FR4 with a thickness of 1.4mm, a relative dielectric constant of 4.4 and a loss tangent value of 0.02; After passing through the metal feed line 4, the current couples energy to the subwavelength grid patch 6 in the form of coupled feed, and then radiates electromagnetic waves outward by the subwavelength grid patch 6; Similar to the principle of ±45° polarization current formed by the metal feed line 4, the subwavelength grid patch 6 realizes the distribution of ±45° polarization current, so that the antenna radiates ±45° polarized electromagnetic waves outward;

[0035] The inner core of the coaxial probe 1 is connected with the feed line 3-1 of the balun 3, and the outer core is connected with the ground plate 3-2 of the balun 3, and the current is fed to the balun 3 through the coaxial probe 1; The balun ground plate 3-2 is connected with the metal feed line 4, the current is fed to the metal feed line 4 through the balun ground plate 3-2, and then the energy is coupled to the subwavelength grid patch 6 by the metal feed line 4, and finally the electromagnetic waves are radiated outward by the subwavelength grid patch 6.

[0036] The simulation test of the above-mentioned sub-wavelength grid patch-based dual-polarized metasurface antenna is shown in Fig. Figure 6 ,7; more specifically: Figure 6 The S parameters of the metasurface antenna are shown. The reflection coefficients |S11| and |S22| of the antenna dual-port are less than -10 dB in the frequency band of 3.4-4.1 GHz. In the working frequency band, the isolation of the antenna dual-port is higher than 23 dB, and the dual-polarized port isolation meets the requirements of the communication system. Figure 7 The horizontal plane radiation patterns of the metasurface antenna at 3.4 GHz, 3.7 GHz, 3.9 GHz and 4.1 GHz are given, and the far-field radiation performance of the metasurface antenna is stable. In the working frequency band, the gain of the antenna is about 9.4±0.6dBi.

[0037] In summary, the sub-wavelength patch-based dual-polarized metasurface antenna of the present application has the advantages of low profile, wide bandwidth and stable radiation; the present application uses a balanced balun feed 3 to replace the traditional slot feed structure of the metasurface antenna, solving the problem of damage to the back radiation frequency circuit caused by back radiation of the slot feed; the metal feed line 4 adopts an L-shaped metal structure, so that the currents in the vertical and horizontal directions are superimposed to form currents in the ±45° direction, realizing the ±45° polarization radiation of the metasurface antenna; compared with the base station microstrip patch antenna, the present application uses a sub-wavelength grid patch 6 to replace the microstrip patch, widening the antenna bandwidth and meeting the demand of the base station for low profile and wide bandwidth. The profile height of the metasurface antenna is 8.4 mm. The antenna can work in the frequency band of 3.4-4.1 GHz and has stable radiation performance. The dual-polarized metasurface antenna has the advantages of low profile, wide bandwidth and stable radiation. The antenna has great application value for communication base stations.

[0038] Therefore, the embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-mentioned specific embodiments, and the above-mentioned embodiments are only illustrative but not limiting. Those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which all belong to the protection of the present application. The part not described in detail in the present application belongs to the known technology of those skilled in the art.

Claims

1. A sub-wavelength patch based dual-polarized metasurface antenna, characterized in that, The coaxial probe (1), the metal ground plate (2), the balanced feed balun (3), the metal feed line (4), the dielectric substrate (5) and the subwavelength grid patch (6) are sequentially stacked from bottom to top. The two balanced feed baluns (3) are vertically crossed and vertically placed on the metal ground plate (2); each balanced feed balun is composed of a feed line (3-1) and a balun ground plate (3-2); the feed line (3-1) is connected with the inner core of the coaxial probe (1), the lower edge of the balun ground plate is connected with the ground plate, and the upper edge is connected with the metal feed line (4); meanwhile, one of the balanced feed baluns adopts a feed line bridge structure (3-3), and the feed line is bent downward by a part, so that both feed lines can work normally after the two balanced feed baluns (3) are vertically crossed; The metal feed line (4) is composed of four L-shaped feed lines, each of which is composed of a first metal line (4-1), a second metal line (4-2) and a metal connecting part (4-3); to make the current in the vertical direction and the horizontal direction form a current in the ±45° direction through vector superposition; The subwavelength grid patch (6) is composed of twenty-five small patches arranged in a 5x5 array; The dielectric substrate (5) is placed on the balanced feed balun (3), the upper surface of the dielectric substrate (5) is printed with the subwavelength grid patch (6), and the lower surface of the dielectric substrate (5) is printed with the metal feed line (4); The current is fed to the balanced feed balun (3) through the coaxial probe (1); the current is fed to the metal feed line (4) through the balun ground plate (3-2), and then the energy is coupled to the subwavelength grid patch (6) by the metal feed line (4), and finally the energy is radiated outward in the form of electromagnetic waves by the subwavelength grid patch (6); The dielectric substrate adopts 1mm thick FR4 with a relative dielectric constant of 4.4 and a loss tangent of 0.02; The profile height of the metasurface antenna is 8.4mm; The metasurface antenna can work at 3.4-4.1GHz.

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