Low-profile dual-frequency fusion antenna based on dual-function structure, and communication device

Abstract

Disclosed in the present invention are a low-profile dual-frequency fusion antenna based on a dual-function structure, and a communication device. The low-profile dual-frequency fusion antenna comprises a meta-surface structure, rectangular parasitic strips, a high-frequency antenna radiation unit and a reflective plate, wherein the high-frequency antenna radiation unit is arranged above the reflective plate; the meta-surface structure is arranged above the high-frequency antenna radiation unit; and the rectangular parasitic strips are arranged above the high-frequency antenna radiation unit and located below the meta-surface structure. In the present invention, the structure is simple, the overall antenna profile is low, and the degree of isolation is high.

Description

A low-profile dual-frequency fusion antenna and communication equipment based on a dual-function structure Technical Field

[0001] The present invention relates to the field of mobile communications, and in particular to a low-profile dual-frequency fusion antenna and communication equipment based on a dual-function structure. Background Art

[0002] With the continuous development of mobile communication technology, mobile communication technology has enriched our lives. With the changes in communication systems, there are now multiple communication systems, and it is expected that multiple communication application standards will coexist for a long time in the future. Currently, the communication systems used in my country are 2G, 3G, 4G, and 5G. Antennas are an important component of communication systems, and their performance directly affects the communication functions of wireless systems. Therefore, the research on multi-frequency antennas that can simultaneously support multiple standards has a strong application background. With the increase in communication frequency bands required by communication standards and the introduction of new communication technologies (such as MIMO), the number of antennas mounted on the same base station site continues to increase. However, base station site selection is difficult and antenna resources are scarce. How to place multi-band and multi-antennas in a limited space is of great research value.

[0003] In order to solve this problem, scholars have adopted the method of co-aperture fusion, that is, putting antennas of different frequency bands compactly together, trying to make the antennas work normally in different frequency bands. When antennas working in different frequency bands are fused in the co-aperture, due to mutual coupling, the impedance matching, port isolation and radiation performance will be deteriorated. Some scholars have adopted the method of metasurface loading to solve the coupling problem in the co-aperture, but it increases the antenna structure and increases the wind resistance. Furthermore, some scholars have achieved antenna co-aperture by integrating the low-frequency antenna and the metasurface structure. In this type of design, the overall cross-sectional height of the antenna is usually 0.2λ. L (where λ L is the free space wavelength at the lowest frequency point at low frequency), there is still room for further antenna miniaturization to save antenna space.

[0004] Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a low-profile dual-frequency fusion antenna based on a dual-function structure.

[0006] The present invention reuses the metasurface structure as part of the low-frequency antenna radiation unit, enabling the low-frequency antenna radiation unit to operate normally. At the same time, due to the high-frequency transmission characteristics of the metasurface structure, the problem of high-frequency antenna radiation being blocked by the low-frequency antenna in a co-aperture layout is solved.

[0007] The present invention reuses a rectangular parasitic strip structure to broaden the low-frequency bandwidth while improving the high-frequency antenna gain, ultimately achieving the co-aperture fusion of two broadband antennas operating in different frequency bands.

[0008] Another object of the present invention is to provide a communication device.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A low-profile dual-band fusion antenna based on a dual-function structure includes a metasurface structure, a rectangular parasitic strip, a high-frequency antenna radiating unit, and a reflector. The high-frequency antenna radiating unit is arranged above the reflector, the metasurface structure is arranged above the high-frequency antenna radiating unit, the metasurface structure is arranged on the first surface of a dielectric substrate, and the rectangular parasitic strip is arranged on the second surface of the dielectric substrate. The metasurface structure and the rectangular parasitic strip constitute the low-frequency antenna radiating unit.

[0011] When the metasurface structure is excited, a coupled current flows through the rectangular parasitic strips, creating a resonance point in the antenna's low-frequency range and improving the metasurface's impedance matching. Furthermore, the addition of the rectangular parasitic strips can restore the gain of the high-frequency radiating antenna unit at 2-2.2 GHz.

[0012] Furthermore, the metasurface structure is composed of M×N metasurface units arranged in an array, the array shape is square, and the metasurface units are composed of square rings and square patches embedded in the square rings.

[0013] Furthermore, the metasurface unit includes a first metasurface unit and a second metasurface unit, the metasurface units located at the four corners of the square are the first metasurface units, and the metasurface units located at other positions of the square are the second metasurface units;

[0014] The metasurface structure adopts a differential feeding method. Specifically, the first metasurface unit is connected to the inner core of the coaxial line through a metal column, and the reflector is connected to the outer core of the coaxial line to achieve dual-polarization radiation.

[0015] Furthermore, the square patch sizes of the second metasurface unit and the first metasurface unit are different. By adjusting the square patch sizes of the metasurface units, the transmission performance of the metasurface structure can be controlled.

[0016] Furthermore, the first metasurface unit is provided with an annular groove.

[0017] Furthermore, there are four rectangular parasitic strips, and the four rectangular parasitic strips are rotationally symmetrically arranged around the metasurface structure.

[0018] Furthermore, the high-frequency antenna radiation unit, the metasurface structure, the four rectangular parasitic strips and the reflector are symmetrical about the coaxial axis.

[0019] Furthermore, the high-frequency antenna radiation unit is specifically a dipole antenna.

[0020] Furthermore, the height of the metasurface structure from the reflector is 0.1λ L ,λ L is the free space wavelength at the lowest frequency point.

[0021] A communication device comprises the low-profile dual-frequency fusion antenna.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The frequency band of the present invention covers 860MHz-960MHz and 1700MHz-2200MHz, with gains of 9.5±1dBi and 10±0.5dBi respectively. Compared with other co-aperture fusion antennas, its overall profile is only 0.1λ L (35mm), which has obvious advantages;

[0024] (2) The present invention cleverly utilizes the high-frequency transmission characteristics of the metasurface structure to avoid the problem of concave radiation patterns caused by the high-frequency antenna being blocked by the low-frequency antenna in a co-aperture layout;

[0025] (3) When the metasurface structure in the present invention works as a low-frequency antenna, its operating bandwidth is relatively narrow. The rectangular parasitic strip is set around the metasurface structure to add a resonance point, thereby expanding the bandwidth of the low-frequency antenna. At the same time, due to the addition of the metasurface structure, the high-frequency gain begins to decrease at 2-2.2 GHz. The addition of the rectangular parasitic strip restores the gain at 2-2.2 GHz, ensuring the beam width of the high-frequency antenna.

[0026] (4) The metasurface unit of the present invention includes a square patch and a square ring. Without changing the performance of the low-frequency antenna, the side length of the square patch can be adjusted to achieve the transmittance of the frequency band, which increases the freedom of antenna design. By adjusting the side length of the square, it can be integrated with other frequency bands;

[0027] (5) The present invention sets a metasurface structure above the high-frequency antenna radiation unit, which can serve as a capacitive load for the high-frequency antenna, thereby reducing the cross-section of the high-frequency antenna. The final overall cross-section of the antenna is 0.1λ. L , which realizes the miniaturization of the antenna and saves the space on the antenna surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic structural diagram of the present invention;

[0029] Figure 2 is a front view of Figure 1;

[0030] FIG3 is a top view of the metasurface structure after the high-frequency antenna radiation unit is hidden in FIG1 ;

[0031] FIG4 is a diagram of reflection coefficients of two metasurface units in a high frequency band when no rectangular parasitic strips are loaded in Example 1 of the present invention;

[0032] FIG5( a ) is a comparison diagram of the high-frequency antenna gain under three conditions in Example 1 of the present invention. FIG5( b ) is a comparison diagram of the half-power beamwidth of the high-frequency antenna loaded with a metasurface structure before and after loading a rectangular parasitic strip in Example 1 of the present invention.

[0033] FIG6 is a comparison diagram of impedance matching before and after the metasurface structure is loaded with rectangular parasitic strips in Example 1 of the present invention;

[0034] FIG7( a ) is a schematic diagram of impedance matching of a high-frequency antenna radiation unit in Example 1 of the present invention;

[0035] FIG7( b ) is a schematic diagram of the gain and half-power beamwidth of the high-frequency antenna radiation unit in Example 1 of the present invention;

[0036] FIG7( c ) to FIG7 ( e ) are the directional patterns of the high frequency antenna radiating unit at 1.7 GHz, 1.96 GHz and 2.2 GHz in Example 1 of the present invention;

[0037] FIG8( a ) is a schematic diagram of impedance matching of the low-frequency antenna radiation unit in Embodiment 1 of the present invention.

[0038] FIG8( b ) is a schematic diagram of the gain and half-power beamwidth of the low-frequency antenna radiation unit in Example 1 of the present invention;

[0039] FIG8( c ) to FIG8 ( e ) are the directional patterns of the low-frequency antenna radiation unit at 0.86 GHz, 0.91 GHz and 0.96 GHz in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0041] Example 1

[0042] As shown in Figures 1 to 3, a low-profile dual-band fusion antenna based on a dual-function structure includes a supersurface structure 1, a high-frequency antenna radiation unit 2, a parasitic strip and a reflector 4. The parasitic strip is a rectangular parasitic strip 3, wherein the supersurface structure 1 and the rectangular parasitic strip 3 together constitute a low-frequency antenna radiation unit.

[0043] In this embodiment, the high-frequency antenna radiating element 2 is placed above the reflector 4 at a distance of 30 mm. The metasurface structure is placed 5.5 mm above the high-frequency antenna radiating element. The dielectric substrate of the metasurface structure has a relative dielectric constant of 3.55 and a thickness of 1.524 mm. The dielectric substrate of the high-frequency antenna radiating element has a relative dielectric constant of 2.2 and a thickness of 0.51 mm.

[0044] Furthermore, the metasurface structure is provided on the first surface of the dielectric substrate, and the rectangular parasitic strip is provided on the second surface of the same dielectric substrate. The first surface and the second surface are opposite surfaces. In this embodiment, the first surface is the upper surface of the dielectric substrate, and the second surface is the lower surface of the dielectric substrate.

[0045] Specifically, there are four rectangular parasitic strips, which are rotationally symmetrically arranged on the lower surface of the dielectric substrate and around the metasurface structure. The overall structure of the metasurface structure is a square, and a rectangular parasitic strip is correspondingly arranged on the outside of each side of the square.

[0046] This embodiment realizes the dual-frequency co-aperture fusion of the antenna. However, in the interspersed layout, when the high-frequency antenna radiating unit is placed below the low-frequency antenna radiating unit, since the low-frequency antenna radiating unit is an electrically larger shield than the high-frequency antenna radiating unit, the low-frequency antenna radiating unit will cause radiation shielding to the high-frequency antenna radiating unit within the high-frequency working frequency band, resulting in impedance matching mismatch and radiation pattern distortion of the high-frequency antenna radiating unit, and the distortion includes characteristic depression, deflection and jitter ripples. In order to overcome the above-mentioned defects, the present invention is cleverly designed to design the super-surface structure in the low-frequency antenna radiating unit as an adjustable frequency selective surface with high-frequency transmission, so that the present invention can achieve normal radiation of the high-frequency antenna radiating unit without adding any other additional structures.

[0047] The high-frequency reflection coefficient of the metasurface unit in this embodiment is shown in Figure 4. This primarily measures the reflection coefficient of a plane wave from the lower to upper surface of the metasurface unit. If there is a dip within a certain frequency band, it indicates that relatively little energy is reflected at that frequency point, and the vast majority of the plane wave successfully transmits to the other side. It is generally believed that the closer the reflection coefficient is to 0, the less likely the wave is to transmit, and the further it is from 0, the more likely it is to transmit. When the reflection coefficient reaches below -10dB, it indicates that 90% of the plane wave's energy is transmitted.

[0048] As shown in FIG4 , in this embodiment, when the rectangular parasitic strip is not loaded, the average reflection coefficient of the two metasurface units reaches -8 dB, achieving high transmission performance.

[0049] Furthermore, the present invention controls the high-frequency transmission performance of the metasurface structure by adjusting the side length of the square patch to change the lowest point frequency. Specifically, as the size of the square patch increases, the concave point moves toward lower frequencies, resulting in better low-frequency transmission performance. When the metasurface structure of the present invention operates as a partially reflecting surface, it improves and maintains gain within some high-frequency bands. However, at 2-2.2 GHz, its gain begins to roll off. By adding rectangular parasitic strips, the antenna's gain and bandwidth within the 2-2.2 GHz band are restored, as shown in Figures 5(a) and 5(b).

[0050] In this embodiment, when the metasurface structure is excited, a coupled current appears on the rectangular parasitic strip. This coupled current is equivalent to a dipole, forming a resonance point at low frequencies. Its length determines the resonant frequency of the antenna. The rectangular parasitic strip acts as a capacitive load, improving the impedance matching of the metasurface structure. As shown in Figure 6, after adding the rectangular parasitic strip, the impedance matching increases from -5dB to -15dB.

[0051] Furthermore, the metasurface structure is composed of M×N metasurface units arranged in an array. The array shape is square, and dual polarization is achieved at ±45°. In this embodiment, the square is preferably a square. The metasurface unit includes a square ring and a square patch embedded in the square ring. The metasurface unit has a symmetrical structure, which satisfies the high-frequency radiation antenna unit's polarized waves in both directions and has the same transmittance.

[0052] Specifically, the metasurface unit includes a first metasurface unit 8A and a second metasurface unit 8B, and the square patch sizes of the first and second metasurface units are different.

[0053] Preferably, the first metasurface units are arranged at the four corners of the square matrix, and the second metasurface units are arranged at locations other than the four corners. By adjusting the square patch size of the second metasurface units to be different from that of the first metasurface units, the frequency band reflectivity is changed, which can better restore the radiation performance and S parameters of the high-frequency antenna while maintaining low-frequency performance.

[0054] To offset the excessive inductance of the low-frequency antenna, a circular groove 9 is formed on the first metasurface unit 8A. The center of the circular groove is located where the coaxial inner diameter meets the metasurface structure. By adjusting the inner and outer diameters of the circular groove, its impedance matching can be adjusted. In this embodiment, the inner diameter of the circular groove is 2.9 mm, and the outer diameter is 3.02 mm.

[0055] Since the loading height of the metasurface structure affects not only the performance of the high-frequency antenna, but also the matching of the low-frequency antenna, this embodiment not only negligibly affects the performance of the high-frequency antenna by opening a circular groove, but also optimizes the performance of the low-frequency antenna; the height of the metasurface structure and the loading distance of the reflector will bring about inductive changes in the impedance matching of the low-frequency antenna, which can be adjusted back by the inner and outer diameters of the circular groove.

[0056] In this embodiment, the height between the lower surface of the dielectric substrate of the high-frequency antenna radiation unit and the reflector is 30 mm. The height between the metasurface structure and the reflector is 35.5 mm, specifically 0.1λ L , where λ L is the free space wavelength at the lowest frequency point.

[0057] The metasurface structure adopts a differential feeding form and is realized by four coaxial cables and metal pillars, wherein the outer cores of the coaxial cables are all connected to the reflector, and the four inner cores are respectively connected to the four metal pillars 5A, 5B, 5C, and 5D. The four metal pillars are then respectively connected to the first metasurface units 8A at the four corners. Among them, the metal pillars 5A and the metal pillars 5C form a pair of differential feeding. When they are fed with equal-amplitude and anti-phase excitation, the low-frequency antenna will radiate outward in a -45-degree linear polarization manner. The metal pillars 5B and the metal pillars 5D form another pair of differential feeding, which can form 45-degree linear polarization.

[0058] In this embodiment, the preferred dimensions of the metasurface structure are:

[0059] The metasurface structure adopts a coplanar layout of 3x3 metasurface units. The metasurface unit is composed of a square patch and a square ring. In this embodiment, the inner side length of the square ring of the first and second metasurface units 8A and 8B is 36.1mm, the outer side length is 36.3mm, the unit period of the metasurface unit is 40.5mm, the side length of the square patch of the first metasurface unit 8A is 31mm, and the side length of the square patch of the second metasurface unit 8B is 29.8mm.

[0060] The high-frequency antenna radiating unit includes a first high-frequency radiating arm 7A, a second high-frequency radiating arm 7B, a third high-frequency radiating arm 7C, a fourth high-frequency radiating arm 7D, high-frequency feeder structures 10A and 10B, and coaxial cables 6A and 6B. The first high-frequency radiating arm 7A, the second high-frequency radiating arm 7B, and the high-frequency feeder 10B are printed on the lower surface of the high-frequency dielectric substrate, while the third high-frequency radiating arm 7C, the fourth high-frequency radiating arm 7D, and the high-frequency feeder 10A are printed on the upper surface of the high-frequency dielectric substrate. The first high-frequency radiating arm 7A and the third high-frequency radiating arm 7C form a -45-degree polarized dipole, which is fed by the high-frequency feeder 10B. The second high-frequency radiating arm 7B and the fourth high-frequency radiating arm 7D form a 45-degree polarized dipole, which is fed by the high-frequency feeder 10A. The two coaxial cables are connected to the high-frequency feeders 10A and 10B, respectively.

[0061] The two high-frequency feed lines are perpendicular to each other, and the intersection is located at the center point of the high-frequency dielectric substrate.

[0062] The four high-frequency radiation arms have the same structure and size, and are all printed on a high-frequency dielectric substrate.

[0063] The high-frequency coaxial line is perpendicular to the high-frequency feed line 10A and the high-frequency feed line 10B.

[0064] The operating frequency band of the high-frequency antenna is 1700MHz-2200MHz, and the operating frequency band of the low-frequency antenna is 860MHz-960MHz.

[0065] As shown in Figures 7(a) to 7(e), the impedance bandwidth, isolation, gain, half-power beamwidth, and radiation pattern of the high-frequency antenna in this embodiment are shown. The high-frequency antenna of the present invention has a port isolation of more than 30 dB within a bandwidth of 1700 MHz to 2200 MHz, and the beam width is stable within 60-65 degrees, with a gain of 10±0.5 dBi.

[0066] As shown in Figures 8(a) to 8(e), the impedance bandwidth, isolation, gain, half-power beamwidth, and radiation pattern of the low-frequency antenna in this embodiment are shown. The port isolation of the low-frequency antenna in the present invention can reach more than 45dB within the bandwidth of 860MHz-960MHz, but the beamwidth is narrow and the gain is 9.5±1dBi.

[0067] The dual-band fusion antenna has the characteristics of novel structure, simple operation, convenient production and low profile.

[0068] Example 2

[0069] A communication device, including a low-profile dual-frequency fusion antenna based on a dual-function metasurface as described in Example 1, which includes, from top to bottom, a metasurface structure, a rectangular parasitic strip, a high-frequency antenna radiation unit and a reflector.

[0070] The above embodiments are preferred implementations of the present invention, but the implementation of the present invention is not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A low-profile dual-frequency fusion antenna based on a dual-function structure, characterized in that: It includes a super surface structure, a high-frequency antenna radiation unit and a reflection plate, wherein the high-frequency antenna radiation unit is arranged above the reflection plate, the super surface structure is arranged above the high-frequency antenna radiation unit, the super surface structure is arranged on the first surface of the dielectric substrate, a rectangular parasitic strip is arranged on the second surface of the dielectric substrate, and the super surface structure and the rectangular parasitic strip constitute a low-frequency antenna radiation unit; The rectangular parasitic strip is used to restore the gain of the high-frequency antenna radiating element at 2-2.2GHz.

2. The low-profile dual-frequency fusion antenna according to claim 1, characterized in that: The metasurface structure is composed of M×N metasurface units arranged in an array, the array shape is a square, and the metasurface unit is composed of a square ring and a square patch embedded in the square ring.

3. The low-profile dual-frequency fusion antenna according to claim 2, characterized in that: The super surface unit includes a first super surface unit and a second super surface unit, the super surface units located at the four corners of the square are the first super surface units, and the super surface units located at other positions of the square are the second super surface units; The metasurface structure adopts a differential feeding method, specifically, the first metasurface unit is connected to the inner core of the coaxial line, and the reflector is connected to the outer core of the coaxial line to achieve dual-polarization radiation.

4. The low-profile dual-frequency fusion antenna according to claim 3, characterized in that: The square patch sizes of the second metasurface unit and the first metasurface unit are different. The high-frequency transmission performance of the metasurface structure is controlled by adjusting the square patch sizes of the two metasurface units.

5. The low-profile dual-frequency fusion antenna according to claim 4, characterized in that: The first super surface unit is provided with an annular groove.

6. The low-profile dual-frequency fusion antenna according to any one of claims 1 to 5, characterized in that: There are four rectangular parasitic strips, and the four rectangular parasitic strips are rotationally symmetrically arranged around the metasurface structure.

7. The low-profile dual-frequency fusion antenna according to claim 6, characterized in that: The high-frequency antenna radiation unit, the metasurface structure, the four rectangular parasitic strips and the reflector are symmetrical about the coaxial line.

8. The low-profile dual-frequency fusion antenna according to claim 1, characterized in that: The high-frequency antenna radiation unit is specifically a dipole antenna.

9. The low-profile dual-frequency fusion antenna according to claim 1, characterized in that: The height of the metasurface structure from the reflector is 0.1λ L ,λ L is the free space wavelength at the lowest frequency point.

10. A communication device, characterized in that: It comprises the low-profile dual-frequency fusion antenna as described in any one of claims 1-9.

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