A metasurface-based beam reconfigurable antenna

Abstract

The present invention discloses a beam reconfigurable antenna based on metasurface, belonging to the technical field of radio frequency antennas. Based on a log-periodic antenna, a phase gradient metasurface structure is loaded. By utilizing the increasing equal phase difference presented by the carefully designed meandering structure, the end-fire beam radiated by the antenna is transformed into a beam at 64° with the plane where the radiator is located. This gradient phase-matched log-periodic antenna realizes the beam deflection of the radiator, and at the same time, the antenna has the characteristics of miniaturization and wide bandwidth.

Description

Technical Field

[0001] The present invention belongs to the technical field of radio frequency antennas, and particularly relates to a beam reconfigurable antenna based on a metasurface. Background Art

[0002] The beam deflection of an antenna applied to a communication system is a crucial research direction in the technical field of radio frequency antennas. A metasurface antenna is a new type of antenna structure that has emerged in recent years. The metasurface has the function of amplitude and phase regulation, and can realize the direction deflection and gain improvement of electromagnetic waves. The antenna can change the antenna beam by loading the metasurface. The characteristic of arbitrarily regulating electromagnetic waves by the metasurface structure enables many traditional high-performance antennas to be replaced by metasurface antennas, and has a smaller volume and a simpler structure. At present, most metasurface antennas focus on designing a reflectarray antenna or a lens antenna. Although such antennas have good performance, they have a relatively high profile, which is not conducive to the development of antenna miniaturization. Some scholars have proposed to place the antenna feeding structure and the metasurface structure in the same horizontal plane to reduce the antenna profile. However, due to the change in the polarization mode of electromagnetic waves, the radiation efficiency of the antenna is affected, resulting in poor performance.

[0003] Therefore, the invention patent CN113745846A discloses a phase gradient metasurface antenna with a microstrip-like feeding structure, which is composed of a microstrip-like feeding structure and a radiator of the phase gradient metasurface. The microstrip feeding structure includes an SMA coaxial connector, a rectangular waveguide, a horn waveguide, and a microstrip-like line; wherein the microstrip-like line is composed of an upper metal strip, a lower metal plate, and a metal connection strip. The radiator of the phase gradient metasurface includes more than 2 metamaterial units, a dielectric substrate, and a metal ground; this antenna can reduce the antenna profile. Using the phase gradient metasurface to control the pointing of the radiation pattern can not only overcome the disadvantages of a large volume of a parabolic antenna and complex feeding of an array antenna, but also achieve the advantage of high degrees of freedom. However, the deflection angle of the antenna direction of this patent is a dual-beam. A horizontally incident electromagnetic wave is provided for the radiator of the phase gradient metasurface through a microstrip-like feeding network, and a vertical radiation is generated by exciting the metamaterial unit structure. Then, the beam angle is controlled by the phase difference between the metamaterial units. Since it adopts a deflection dual-beam form, it has the deficiency that the beam gain is not concentrated enough.

[0004] At present, in terms of realizing beam deflection of a metasurface-based antenna, how to make the antenna have the characteristics of miniaturization and wide frequency while rotating the antenna radiation beam and making the beam gain more concentrated is a problem to be solved. Summary of the Invention

[0005] The object of the present invention is to provide a metasurface-based beam reconfigurable antenna. Based on an end-fire antenna, a metasurface structure is loaded, and the phase gradient metasurface structure is used to realize the deflection of the antenna radiation beam. While the antenna has the characteristics of miniaturization and wideband based on the metasurface structure and its phase adjustment characteristics, the antenna radiation beam is rotated.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a metasurface-based beam reconfigurable antenna, which is composed of a radiator and a metasurface structure. The radiator adopts a log-periodic antenna structure, and the metasurface structure is placed on one side of the beam radiation direction of the radiator; wherein, the radiator includes a dielectric substrate (1), a first oscillator (2), a second oscillator (3), a first collector line (4) and a second collector line (5); the dielectric substrate (1) is made of polymer material, the first oscillator (2) and the first collector line (4) are located on the upper surface of the dielectric substrate (1), the second oscillator (3) and the second collector line (5) are located on the lower surface of the dielectric substrate (1), the first oscillator (2) is connected to the first collector line (4), the second oscillator (3) is connected to the second collector line (5), and the first oscillator (2) and the second oscillator (3) are arranged in a cross pattern; a feeding structure (6) intervenes from the high-frequency end; the metasurface structure is composed of a periodic array structure (7) on both sides of the dielectric substrate (1) and a metal backplane (8); the periodic array structure (7) is a metal patch, which is composed of a plurality of identical phase gradient units (9), and each phase gradient unit (9) includes a first phase structure (10), a second phase structure (11), a third phase structure (12), a fourth phase structure (13), a fifth phase structure (14), and a sixth phase structure (15) formed by the metal strips of the metal patch. From the first phase structure (10) to the sixth phase structure (15), there is a phase gradient change, providing phases of 150°, 90°, 30°, -30°, -90°, and -150° in sequence.

[0008] Further, the opening angle of the log-periodic antenna structure of the radiator where the period constant τ = 0.8 - 0.95 and the spacing factor σ = 0.08 - 0.51.

[0009] Further, the number of oscillators of the radiator The oscillator spacing d = 4 * L1 * σ, the length of the longest oscillator L1 = (1.01 - 0.519τ) * 0.0162, and the lengths of the other oscillators L n = τ * L n-1 , and the length of the collector line

[0010] Further, the periodic arrangement spacing of each phase structure of the phase gradient unit (9) in the transverse direction The periodic arrangement pitch Y in the longitudinal direction = (0.52 - 0.54)*lamda', where c = 3*10 8 m / s is the speed of light and f is the working frequency point; the symmetric center point of each phase structure is located at the center point of the rectangle defined by X and Y.

[0011] Furthermore, the width W of the metal strip of each phase structure = (0.01 - 0.02)*lamda'.

[0012] Furthermore, the first phase structure (10) is a cross-shaped structure, with the transverse length L = (0.11 - 0.13)*lamda' and the longitudinal length S1 = (0.035 - 0.045)*lamda'.

[0013] Furthermore, the second phase structure (11) is a cross-shaped structure, with the transverse length L = (0.11 - 0.13)*lamda' and the longitudinal length S2 = (0.11 - 0.14)*lamda'.

[0014] Furthermore, the third phase structure (12) is an L-shaped structure extending counterclockwise from both longitudinal ends based on the cross-shaped structure. The transverse length L of the cross-shaped structure = (0.11 - 0.13)*lamda' and the longitudinal length S2 = (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the L-shaped structure W2 = 3*W, and the second vertical segment extends inward with a length S3 = (0.013 - 0.016)*lamda'.

[0015] Furthermore, the fourth phase structure (13) is an L-shaped structure extending counterclockwise from both longitudinal ends based on the cross-shaped structure. The transverse length L of the cross-shaped structure = (0.11 - 0.13)*lamda' and the longitudinal length S2 = (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the L-shaped structure W2 = 3*W, and the second vertical segment extends inward with a length S4 = (0.049 - 0.053)*lamda'.

[0016] Furthermore, the fifth phase structure (14) is a first L-shaped structure extending counterclockwise from both longitudinal ends of a cross-shaped structure and a second L-shaped structure continuing to extend from the end of the first L-shaped structure. The transverse length L of the cross-shaped structure is (0.11 - 0.13)*lamda', and the longitudinal length S2 is (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the first L-shaped structure is W2 = 3*W, and the second vertical segment extends inward with a length S4 = (0.049 - 0.053)*lamda'; the length of the first horizontal segment of the second L-shaped structure extends outward with a length W2 = 3*W, and the second vertical segment extends outward with a length S5 = (0.013 - 0.016)*lamda'.

[0017] Furthermore, the sixth phase structure (15) is a first L-shaped structure extending counterclockwise from both longitudinal ends of a cross-shaped structure and a second L-shaped structure continuing to extend from the end of the first L-shaped structure. The transverse length L of the cross-shaped structure is (0.11 - 0.13)*lamda', and the longitudinal length S2 is (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the first L-shaped structure is W2 = 3*W, and the second vertical segment extends inward with a length S4 = (0.049 - 0.053)*lamda'; the length of the first horizontal segment of the second L-shaped structure extends outward with a length W2 = 3*W, and the second vertical segment extends outward with a length S6 = (0.049 - 0.053)*lamda'.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention designs a phase gradient metasurface structure, and the phase gradient unit adopts a gyratory bending structure. On the one hand, the gyratory bending structure increases the current path at the same operating frequency, so it is beneficial to reduce the unit size; on the other hand, within the phase gradient unit, by carefully designing the gyratory bending structure, the length of the metal line gradually increases and the phase gradually decreases, showing an increasing equal phase difference of 60° and including a 360° phase. This gradient phase-matched log-periodic antenna realizes the beam deflection of the radiator, and at the same time, the antenna has the characteristics of miniaturization and wide bandwidth. Based on the principle that electromagnetic waves can change the beam direction after passing through a discontinuous phase metasurface, this phase gradient metasurface converts the end-fire beam radiated by the antenna into a beam at 64° with the plane where the radiator is located. By adjusting the radiation angle of the antenna, the communication distance can be effectively improved and it can be applied in many occasions where the radiation angle needs to be adjusted. Moreover, the present invention is based on the radiation beam of the end-fire antenna. By loading the metasurface structure, the radiation beam of the antenna is directly deflected by the phase gradient metasurface structure. In this design, the interaction mode between the radiator and the phase gradient metasurface structure will not produce double beams, and the beam gain is more concentrated. Description of the Drawings

[0020] Figure 1 Side view of a metasurface-based beam reconfigurable antenna;

[0021] Figure 2 Top view of a metasurface-based beam reconfigurable antenna;

[0022] Figure 3 Top view of phase gradient unit 9;

[0023] Figure 4 VSWR diagram of a metasurface-based beam reconfigurable antenna provided by an embodiment of the present invention;

[0024] Figure 5 Gain pattern of a metasurface-based beam reconfigurable antenna provided by an embodiment of the present invention. Specific implementation manners

[0025] To make the above features and advantages of the present invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows.

[0026] This embodiment provides a metasurface-based beam reconfigurable antenna. The relevant dimension data of the antenna adopts the optimal dimensions to obtain an antenna with optimal performance. As Figure 1 shown, reference numeral 1 is a polymer material with a dielectric constant of 3.2. Reference numerals 2, 3, 4, 5, 6, 7, and 8 are copper.

[0027] As Figure 2 shown, the flare angle α of the log-periodic antenna is 31.6°, the period constant τ is 0.83, the spacing factor σ is 0.145, the number of elements n is 9, the spacing between adjacent elements d is 5.6 mm, the longest element L1 is 9.4 mm, and the length of the collector line Y1 is 30.1 mm. The phase gradient unit 9 forms a 4×5 periodic array.

[0028] As Figure 3 shown, in the phase gradient unit 9, Y = 8.83 mm, X = 4.41 mm, W = 0.2 mm, L = 1.83 mm, S1 = 0.71 mm, S2 = 2.06 mm, S3 = 0.25 mm, S4 = 0.87 mm, S5 = 0.25 mm, S6 = 0.87 mm, and W2 = 0.6 mm.

[0029] Figure 4 VSWR simulation results of a metasurface-based beam reconfigurable antenna provided by this embodiment, through Figure 4As can be seen from the curves in [the figure], without the metasurface loaded, within the frequency band of 7.75 GHz - 9.65 GHz, the voltage standing wave ratio (VSWR) ≤ 1.65; after loading the metasurface, within the frequency band of 7.75 GHz - 9.65 GHz, the VSWR ≤ 2. This shows that after loading the metasurface, a good VSWR can still be achieved within a wide frequency band.

[0030] Figure 5 The simulation results of the gain pattern of a beam reconfigurable antenna based on a metasurface provided in this embodiment are as follows. Through Figure 5 it can be seen that without the metasurface loaded, at 9 GHz, the antenna gain is 9.53 dB and the beam direction is 0°; after loading the metasurface, at 9 GHz, the antenna gain is 9.27 dB and the beam direction is 64°. It can be known that through the optimized best size by simulation, the VSWR and gain of the antenna at 9 GHz are both the best simulation results. From the simulation results, it can be seen that for a beam reconfigurable antenna based on a metasurface provided by the present invention, its VSWR and gain are good.

[0031] For the sake of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "upper...", etc. can be used here to describe the spatial position relationship between a device or feature shown in the figure and other devices or features. It should be understood that spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the figure is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0032] In addition, it should be noted that using words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without additional declaration, the above words have no special meaning, so it cannot be understood as a limitation to the protection scope of the present invention.

[0033] The parts not detailed in the present invention are well-known technologies to those skilled in the art.

[0034] Although the present invention has been disclosed as above with embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention. The protection scope of the present invention is defined by the claims.

Claims

1. A metasurface-based beam reconfigurable antenna, characterized in that It consists of a radiator and a metasurface structure. The radiator adopts a log-periodic antenna structure, and the metasurface structure is placed on one side of the beam radiation direction of the radiator. Among them, the radiator includes a dielectric substrate (1), a first oscillator (2), a second oscillator (3), a first collector line (4) and a second collector line (5); the dielectric substrate (1) is made of polymer material, the first oscillator (2) and the first collector line (4) are located on the upper surface of the dielectric substrate (1), the second oscillator (3) and the second collector line (5) are located on the lower surface of the dielectric substrate (1), the first oscillator (2) is connected to the first collector line (4), the second oscillator (3) is connected to the second collector line (5), and the first oscillator (2) and the second oscillator (3) are arranged in a cross pattern; a feeding structure (6) is accessed from the high-frequency end; the metasurface structure is composed of a periodic array structure (7) on both sides of the dielectric substrate (1) and a metal backplane (8); the periodic array structure (7) is a metal patch, which is composed of multiple identical phase gradient units (9). Each phase gradient unit (9) includes a first phase structure (10), a second phase structure (11), a third phase structure (12), a fourth phase structure (13), a fifth phase structure (14), and a sixth phase structure (15) formed by metal strips of the metal patch. The first phase structure (10) to the sixth phase structure (15) all include a cross-shaped structure, and from the first phase structure (10) to the sixth phase structure (15), there is a phase gradient change, providing phases of 150°, 90°, 30°, -30°, -90°, and -150° in sequence.

2. The beam reconfigurable antenna according to claim 1, characterized in that, The flare angle of the log-periodic antenna structure of the radiator where the period constant τ = 0.8 to 0.95, the spacing factor σ = 0.08 to 0.51; the number of radiators the oscillator spacing d = 4 * L1 * σ, the length of the longest oscillator L1 = (1.01 - 0.519τ) * 0.0162, and the lengths of the remaining oscillators L n = τ * L n-1 , the length of the collector 3. The beam reconfigurable antenna according to claim 1, characterized in that, The period arrangement pitch of each phase structure of the phase gradient unit (9) in the transverse direction The period arrangement pitch Y in the longitudinal direction is (0.52 - 0.54)*lamda', where c = 3*10 8 m / s is the speed of light and f is the operating frequency point; the symmetric center point of each phase structure is located at the center point of the rectangle defined by X and Y.

4. The beam reconfigurable antenna according to claim 3, wherein The width W of the metal strip of each phase structure is W=(0.01 - 0.02)*lamda'.

5. The beam reconfigurable antenna according to claim 3 or 4, characterized in that, The first phase structure (10) is a cross-shaped structure, with a transverse length L=(0.11 - 0.13)*lamda' and a longitudinal length S1=(0.035 - 0.045)*lamda'.

6. The beam reconfigurable antenna according to claim 3 or 4, characterized in that, The second phase structure (11) is a cross-shaped structure, with a transverse length L=(0.11 - 0.13)*lamda' and a longitudinal length S2=(0.11 - 0.14)*lamda'.

7. The beam reconfigurable antenna according to claim 4, wherein The third phase structure (12) is an L-shaped structure extending counterclockwise from both longitudinal ends of the cross-shaped structure. The transverse length L of the cross-shaped structure is L=(0.11 - 0.13)*lamda', and the longitudinal length S2 is S2=(0.11 - 0.14)*lamda'; the first horizontal segment length W2 of the L-shaped structure is 3*W, and the second vertical segment extends inward with a length S3=(0.013 - 0.016)*lamda'.

8. The beam reconfigurable antenna according to claim 4, characterized in that, The fourth phase structure (13) is an L-shaped structure extending counterclockwise from both longitudinal ends of the cross-shaped structure. The transverse length L of the cross-shaped structure is L=(0.11 - 0.13)*lamda', and the longitudinal length S2 is S2=(0.11 - 0.14)*lamda'; the first horizontal segment length W2 of the L-shaped structure is 3*W, and the second vertical segment extends inward with a length S4=(0.049 - 0.053)*lamda'.

9. The beam reconfigurable antenna according to claim 4, characterized in that, The fifth phase structure (14) is a first L-shaped structure extending counterclockwise from both longitudinal ends of a cross-shaped structure and a second L-shaped structure continuing to extend from the end of the first L-shaped structure. The transverse length L of the cross-shaped structure is (0.11 - 0.13)*lamda', and the longitudinal length S2 is (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the first L-shaped structure is W2 = 3*W, and the second vertical segment extends inward with a length S4 = (0.049 - 0.053)*lamda'; the length of the first horizontal segment of the second L-shaped structure extends outward with a length W2 = 3*W, and the second vertical segment extends outward with a length S5 = (0.013 - 0.016)*lamda'.

10. The beam reconfigurable antenna according to claim 4, characterized in that, The sixth phase structure (15) is a first L-shaped structure extending counterclockwise from both longitudinal ends of a cross-shaped structure and a second L-shaped structure continuing to extend from the end of the first L-shaped structure. The transverse length L of the cross-shaped structure is (0.11 - 0.13)*lamda', and the longitudinal length S2 is (0.11 - 0.14)*lamda'; the length of the first horizontal segment of the first L-shaped structure is W2 = 3*W, and the second vertical segment extends inward with a length S4 = (0.049 - 0.053)*lamda'; the length of the first horizontal segment of the second L-shaped structure extends outward with a length W2 = 3*W, and the second vertical segment extends outward with a length S6 = (0.049 - 0.053)*lamda'.

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