Liquid crystal holographic metasurface antenna

Abstract

The invention provides a liquid crystal holographic metasurface antenna which is composed of a plurality of identical liquid crystal holographic metasurface panels and a monopole antenna feed source, the liquid crystal holographic metasurface panels are designed by adopting a liquid crystal display processing technology, and a hole is prevented from being formed in the center of a liquid crystal glass plate through a block splicing mode. The monopole antenna feed source is placed at the central hole, the processing difficulty is reduced, the directional diagram and the polarization state of the antenna can be flexibly controlled by independently controlling the liquid crystal dielectric constant of each unit, the control of the directional diagram and the control of the polarization are mutually independent, and the degree of freedom of antenna reconstruction is improved.

Description

Technical Field

[0001] The invention belongs to the field of reconfigurable antennas, in particular to a liquid crystal holographic metasurface antenna which can realize beam scanning and polarization switching. Background Art

[0002] With the development of communication technology, the functional requirements for antennas are becoming more and more complex. Traditional non-reconfigurable antennas with a single performance are gradually unable to meet the application requirements of communication systems. Reconfigurable antennas can flexibly change the antenna radiation performance by changing the antenna structure itself to meet the real-time needs of communication systems. In terms of the changed antenna radiation performance, reconfigurable antennas can be divided into frequency reconfigurable, pattern reconfigurable, polarization reconfigurable, etc. In terms of reconfiguration capability, reconfigurable antennas can be divided into single-performance reconfigurable and multiple-performance hybrid reconfigurable.

[0003] In the current common reconfigurable antenna design, electronically controlled components such as PIN diodes, varactor diodes, MEMS devices, etc. are generally used to achieve antenna reconstruction. The modulation freedom of such components is limited, continuous modulation cannot be achieved, and the power loss at high frequencies is large, which will cause more serious heating and cost problems. Holographic antenna is a new type of artificial impedance modulation antenna, which has the advantages of low profile, conformal, easy integration, simple feeding structure, good control over radiation pattern and polarization, and has been widely studied by scientific researchers at home and abroad. At present, most holographic antennas are non-reconfigurable antennas and reconfigurable antennas loaded with PIN diodes. It is difficult to achieve high modulation efficiency and aperture efficiency, and it is not suitable for high-frequency applications.

[0004] Liquid crystal material is an anisotropic tunable material between solid and liquid. By changing the bias voltage applied to the liquid crystal material, the liquid crystal can present different dielectric constants. The liquid crystal has low power consumption and continuous modulation capability. In summary, based on the application requirements of reconfigurable antennas and the characteristics of liquid crystal materials, it is of great significance to design reconfigurable antennas based on liquid crystal materials. Summary of the invention

[0005] In response to the problems existing in the prior art, the present invention provides a liquid crystal holographic metasurface antenna, which realizes the beam scanning and polarization switching of the antenna by setting the dielectric constant of the liquid crystal. It has the advantages of low profile, low power consumption, easy processing, simple reconstruction method and simple feed structure.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A liquid crystal holographic metasurface antenna comprises a monopole antenna feed and Q liquid crystal holographic metasurface panels, wherein: The Q liquid crystal holographic metasurface panels are sequentially staggered and spliced ​​along the circumferential direction to generate a slot for placing a monopole antenna feed at the center, Q ≥ 3; Each liquid crystal holographic metasurface panel includes liquid crystal holographic metasurface units arranged in a periodic array, and the liquid crystal holographic metasurface unit includes an upper glass substrate, a patch electrode, a liquid crystal layer, a common ground electrode and a lower glass substrate stacked in sequence from top to bottom.

[0007] Furthermore, the ground of the monopole antenna feed is a common ground electrode, and the height of the monopole antenna feed is adjusted by exciting the coaxial connector located on the back of the common ground electrode to adjust the operating frequency.

[0008] Furthermore, the antenna beam pointing is determined by the dielectric constant of the liquid crystal, and beam scanning is achieved by setting the distribution of the dielectric constant of the liquid crystal layer.

[0009] Furthermore, the polarization state of the antenna is determined by the dielectric constant of the liquid crystal, and polarization switching is achieved by setting the distribution of the dielectric constant of the liquid crystal layer.

[0010] Furthermore, in each liquid crystal holographic metasurface panel, the common ground electrode of all liquid crystal holographic metasurface units is applied with the same voltage, and the patch electrodes are applied with independent voltages.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention adopts liquid crystal material to realize holographic antenna, which can realize continuous regulation and can more effectively realize the beam scanning and polarization switching performance of the antenna; the antenna regulation has low power consumption, is easy to integrate, has a simple bias network, and has better application performance in high frequencies; by setting the liquid crystal dielectric constant, the beam pointing and polarization state can be independently regulated at the same time, the antenna has strong reconstruction capability and a wide range of applications; a mature process based on glass plate encapsulation of liquid crystal is adopted, and the central opening of the liquid crystal plate is avoided by splicing multiple plates, and it has good air tightness, stability and processing feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the three-dimensional structure of the liquid crystal holographic metasurface antenna in an embodiment of the present invention; FIG2 (a) is a schematic top view of a liquid crystal holographic metasurface splicing structure in an embodiment of the present invention; FIG2( b ) is a schematic top view of another liquid crystal holographic metasurface splicing structure in an embodiment of the present invention; Figure 3 Schematic diagram of the three-dimensional structure of a monopole antenna feed source in an embodiment of the present invention; Figure 4 Schematic diagram of reflection coefficient of a monopole antenna feed in an embodiment of the present invention; Figure 5Schematic diagram of the three-dimensional structure of a single liquid crystal holographic metasurface panel in an embodiment of the present invention; Figure 6 Schematic diagram of the three-dimensional structure of a liquid crystal holographic metasurface unit in an embodiment of the present invention; Figure 7 Schematic diagram of a curve showing a change in surface impedance of a liquid crystal holographic metasurface unit as a function of a liquid crystal constant in an embodiment of the present invention; Figure 8 Schematic diagram of the dielectric constant distribution of liquid crystal corresponding to the vertical polarized beam pointing to 0° during beam scanning in an embodiment of the present invention; Fig. 9 Schematic diagram of the distribution of the dielectric constant of liquid crystal corresponding to the vertical polarized beam pointing to 15° during beam scanning in an embodiment of the present invention; Fig.10 Schematic diagram of the distribution of the dielectric constant of liquid crystal corresponding to the vertical polarized beam pointing at 30° during beam scanning in an embodiment of the present invention; Fig.11 Schematic diagram of the dielectric constant distribution of liquid crystal corresponding to a vertically polarized beam pointing at 45° during beam scanning in an embodiment of the present invention; Fig.12 Schematic diagram of the gain pattern of the liquid crystal holographic metasurface antenna used for beam scanning in an embodiment of the present invention; Fig.13 Schematic diagram of the distribution of the dielectric constant of the liquid crystal corresponding to the vertical polarization beam pointing to 30° during polarization switching in an embodiment of the present invention; Fig.14 Schematic diagram of the distribution of dielectric constant of liquid crystal corresponding to the horizontal polarized beam pointing to 30° during polarization switching in an embodiment of the present invention; Fig.15 Schematic diagram of the distribution of the dielectric constant of the liquid crystal corresponding to the left-handed circularly polarized beam pointing to 30° during polarization switching in an embodiment of the present invention; Fig.16 Schematic diagram of the distribution of the dielectric constant of the liquid crystal corresponding to the right-handed circularly polarized beam pointing to 30° during polarization switching in an embodiment of the present invention; Fig.17 Schematic diagram of the gain pattern of the liquid crystal holographic metasurface antenna when used for polarization switching in an embodiment of the present invention.

[0013] Among them: 1. Monopole antenna feed; 2. Liquid crystal holographic metasurface panel; 3. Liquid crystal holographic metasurface unit; 4. Upper glass substrate; 5. Patch electrode; 6. Liquid crystal layer; 7. Common ground electrode; 8. Lower glass substrate. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0016] like Figure 1 As shown, a liquid crystal holographic metasurface antenna structure of the present invention is proposed, including: a monopole antenna feed 1, a liquid crystal holographic metasurface panel 2. In order to ensure the feasibility of the polarization switching of the antenna and keep the beam scanning performance of the antenna in the forward and reverse directions consistent, one of the necessary conditions is to make the monopole antenna feed 1 located at the center of the entire liquid crystal holographic metasurface antenna structure. Based on processing technology considerations, the liquid crystal holographic metasurface panel 2 adopts a double-layer glass substrate encapsulation structural design. The processing difficulty of the liquid crystal panel with a hole in the center is relatively large. In order to improve the feasibility of processing, Q blocks of liquid crystal holographic metasurface panels 2 are spliced, Q ≥ 3, to avoid panel openings and realize the center placement of the feed.

[0017] As shown in Figure 2 (a) and Figure 2 (b), a schematic diagram of the splicing structure of the monopole antenna feed 1 and the liquid crystal holographic metasurface panel 2 is proposed, where Figure 2 (a) corresponds to Q=3, and Figure 2 (b) corresponds to Q=4. As mentioned above, as long as Q pieces of liquid crystal holographic metasurface panels 2 can be spliced ​​into a position with a middle hole in a point contact or surface contact manner to place the monopole antenna feed 1, the specific antenna structure design is introduced below using Q=4 as an example. The length of a single liquid crystal panel is 42mm and the width is 40mm. The four liquid crystal holographic metasurface panels 2 are spliced ​​in sequence with an offset width of 2mm. Through splicing, a square groove located in the center is generated, which is 2mm long and 2mm wide. The overall structure of the liquid crystal holographic metasurface antenna is 82mm long and 82mm wide.

[0018] like Figure 3 As shown, it is a schematic diagram of the three-dimensional structure of the monopole antenna feed 1 in the present invention, with a height of 2.5 mm and a diameter of 1 mm.

[0019] like Figure 4 As shown, it is a schematic diagram of the reflection coefficient of the monopole antenna feed 1 in the present invention. The working bandwidth of the monopole antenna feed 1 is 43.77%, and there is good impedance matching at the center frequency.

[0020] like Figure 5As shown, it is a schematic diagram of the three-dimensional structure of a single liquid crystal holographic metasurface panel 2 in an embodiment of the present invention. The metasurface is composed of M×N liquid crystal holographic metasurface units 3 arranged periodically. In this embodiment, the number of liquid crystal holographic metasurface units 3 included in a single liquid crystal holographic metasurface panel 2 is 21×20.

[0021] like Figure 6 As shown, the structure of the liquid crystal holographic metasurface unit 3 in the embodiment of the present invention includes an upper glass substrate 4, a patch electrode 5, a liquid crystal layer 6, a common ground electrode 7 and a lower glass substrate 8 stacked in sequence from top to bottom. In the embodiment of the present invention, the material of the upper glass substrate 4 and the lower glass substrate 8 is selected as Corning's EagleXG glass, with a dielectric constant of 5.2, a thickness of 0.5mm, and a size of 2mm×2mm; the size of the patch electrode 5 is 1.8mm×1.8mm; the dielectric constant of the liquid crystal layer 6 varies in the range of 2.46-3.73, the thickness of the liquid crystal layer 6 is 0.18mm, and the liquid crystal layer 6 is encapsulated by the upper glass substrate 4 and the lower glass substrate 8, the patch electrode 5 is located on the lower side of the upper glass substrate 4, and the common ground electrode 7 is located on the upper side of the lower glass substrate 8. In the liquid crystal holographic metasurface panel 2, the common ground electrode 7 of all liquid crystal holographic metasurface units 3 is applied with the same voltage, and the patch electrode 5 of each liquid crystal holographic metasurface unit 3 is applied with an independent voltage, so that the independent voltage control of each liquid crystal holographic metasurface unit 3 is realized, and the liquid crystal dielectric constant is affected by the voltage, so that the independent control capability of the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3 is obtained. The ground of the monopole antenna feed 1 is also the common ground electrode 7, which is excited by the coaxial connector located on the back of the common ground electrode 7, and the height of the monopole antenna feed 1 can be adjusted to adjust the operating frequency.

[0022] like Figure 7 As shown, it is a schematic diagram of the surface impedance curve of the liquid crystal holographic metasurface unit 3 according to the liquid crystal constant in the embodiment of the present invention. The unit impedance change curve represents the modulation capability of the liquid crystal holographic metasurface unit 3. When the liquid crystal dielectric constant increases, the surface impedance of the liquid crystal holographic metasurface unit 3 increases accordingly. The liquid crystal dielectric constant varies in the range of 2.46-3.73, and the surface impedance modulation range of the liquid crystal holographic metasurface unit 3 is 186.68j ohms-269.80j ohms.

[0023] Figure 8-Figure 12 The liquid crystal dielectric distribution and gain pattern results of the liquid crystal holographic metasurface antenna of the present invention when used for beam scanning, wherein: like Figure 8 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the vertical polarized beam pointing to 0° during beam scanning in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig. 9 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the vertical polarization beam pointing to 15° during beam scanning in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.10 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the vertical polarized beam pointing to 30° during beam scanning in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.11 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the vertical polarized beam pointing to 45° during beam scanning in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3. The center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.12 As shown in the figure, it is a schematic diagram of the gain pattern of the liquid crystal holographic metasurface antenna used for beam scanning in an embodiment of the present invention, the scanning angles are 0°, 15°, 30° and 45° respectively, and the antenna polarization state is fixed to vertical polarization. When the beam scanning angle is 0°, the beam peak gain is 15.96dB; when the beam scanning angle is 15°, the beam peak gain is 17.42dB; when the beam scanning angle is 30°, the beam peak gain is 15.20dB; when the beam scanning angle is 45°, the beam peak gain is 17.11dB.

[0024] Figure 13-Figure 17 is the liquid crystal dielectric distribution and gain pattern results when the liquid crystal holographic metasurface antenna is used for polarization switching, where: like Fig.13 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the vertical polarization beam pointing to 30° during polarization switching in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.14 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the horizontal polarization beam pointing to 30° during polarization switching in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.15As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the left-handed circularly polarized beam pointing to 30° during polarization switching in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.16 As shown, it is a schematic diagram of the distribution of the liquid crystal dielectric constant corresponding to the right-handed circularly polarized beam pointing to 30° during polarization switching in an embodiment of the present invention. The color of each square in the figure represents the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit 3, the center square is the location of the feed source, and the liquid crystal dielectric constant varies in the range of 2.46-3.73; like Fig.17 As shown in the figure, it is a schematic diagram of the gain pattern of the liquid crystal holographic metasurface antenna used for polarization switching in an embodiment of the present invention. The polarization states of the antenna are vertical polarization, horizontal polarization, left-hand circular polarization and right-hand circular polarization, and the beam pointing angle is fixed at 30°. When the polarization state is vertical polarization, the gain of the main polarization component is 15.20dB; when the polarization state is horizontal polarization, the gain of the main polarization component is 14.40dB; when the polarization state is vertical polarization, the gain of the main polarization component is 16.16dB; when the polarization state is vertical polarization, the gain of the main polarization component is 16.93dB.

[0025] The liquid crystal holographic metasurface antenna in the embodiment of the present invention has a simple liquid crystal control method, an easy-to-integrate feeding structure, can achieve beam scanning at a larger angle, can switch between four polarization states (vertical polarization, horizontal polarization, left-hand circular polarization, and right-hand circular polarization), and has a higher radiation gain.

[0026] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid crystal holographic metasurface antenna, characterized in that: It comprises a monopole antenna feed source (1) and Q liquid crystal holographic metasurface panels (2), wherein: The Q liquid crystal holographic metasurface panels (2) are sequentially staggered and spliced ​​along the circumferential direction to generate a slot for placing a monopole antenna feed source (1) at the center, Q ≥ 3; Each liquid crystal holographic metasurface panel (2) comprises liquid crystal holographic metasurface units (3) arranged in a periodic array, wherein the liquid crystal holographic metasurface units (3) comprise an upper glass substrate (4), a patch electrode (5), a liquid crystal layer (6), a common ground electrode (7), and a lower glass substrate (8) stacked in sequence from top to bottom.

2. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that: The ground of the monopole antenna feed source (1) is a common ground electrode (7), and the height of the monopole antenna feed source (1) is adjusted to adjust the operating frequency through the excitation of a coaxial connector located on the back of the common ground electrode (7).

3. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that: The antenna beam direction is determined by the liquid crystal dielectric constant, and beam scanning is achieved by setting the liquid crystal dielectric constant distribution of the liquid crystal layer (6).

4. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that: The polarization state of the antenna is determined by the liquid crystal dielectric constant, and polarization switching is achieved by setting the liquid crystal dielectric constant distribution of the liquid crystal layer (6).

5. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that: In each liquid crystal holographic metasurface panel (2), the common ground electrode (7) of all liquid crystal holographic metasurface units (3) is applied with the same voltage, and the patch electrodes (5) are applied with independent voltages.

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