Liquid crystal holographic metasurface antenna

Abstract

The application 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, wherein the liquid crystal holographic metasurface panel is designed by using a liquid crystal display processing technology, the center opening of the liquid crystal glass plate is avoided by means of block splicing, the monopole antenna feed is placed at the center opening, the processing difficulty is reduced, the liquid crystal dielectric constant of each unit is independently controlled, the antenna directional diagram and polarization state can be flexibly controlled, the control of the directional diagram and the control of the polarization are independent of each other, and the antenna reconstruction degree of freedom is improved.

Description

Technical Field

[0001] This invention belongs to the field of reconfigurable antennas, specifically a liquid crystal holographic metasurface antenna that can realize beam scanning and polarization switching. Background Technology

[0002] With the development of communication technology, the functional requirements for antennas are becoming increasingly complex, and traditional non-reconfigurable antennas with single performance characteristics are gradually becoming unable to meet the application requirements of communication systems. Reconfigurable antennas can flexibly change their radiation performance by altering their structure, thus meeting the real-time needs of communication systems. In terms of the changed antenna radiation performance, reconfigurable antennas can be categorized into frequency reconfigurable, pattern reconfigurable, and polarization reconfigurable antennas. In terms of reconfiguration capability, reconfigurable antennas can be divided into single-performance reconfigurable antennas and hybrid reconfigurable antennas with multiple performance characteristics.

[0003] In current common reconfigurable antenna designs, electronically controlled components such as PIN diodes, varactor diodes, and MEMS devices are generally used to achieve antenna reconfiguration. These components have limited modulation freedom, cannot achieve continuous modulation, and suffer from significant power loss at high frequencies, leading to serious heat generation and cost issues. Holographic antennas are a novel type of artificial impedance modulation antenna, possessing advantages such as low profile, conformal design, easy integration, and simple feeding structure. They also offer good control over radiation patterns and polarization, attracting widespread research from researchers both domestically and internationally. Currently, most holographic antennas are either non-reconfigurable or reconfigurable antennas with PIN diodes, making it difficult to achieve high modulation and aperture efficiencies, and they are not suitable for high-frequency applications.

[0004] Liquid crystal materials are anisotropic tunable materials that exist between solid and liquid states. By changing the bias voltage applied to the liquid crystal material, different dielectric constants can be achieved. Liquid crystals exhibit low power consumption during modulation and continuous modulation capability. In summary, based on the application requirements of reconfigurable antennas and the properties of liquid crystal materials, designing reconfigurable antennas based on liquid crystal materials is of significant importance. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a liquid crystal holographic metasurface antenna. By setting the dielectric constant of the liquid crystal, the antenna can achieve beam scanning and polarization switching. It has the advantages of low profile, low power consumption, easy processing, simple reconfiguration method, and simple feed structure.

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

[0007] A liquid crystal holographic metasurface antenna includes a monopole antenna feed and Q liquid crystal holographic metasurface panels, wherein,

[0008] The Q liquid crystal holographic metasurface panels are sequentially staggered and spliced ​​along the circumferential direction to create a slot at the center position for placing the monopole antenna feed, where Q≥3;

[0009] Each liquid crystal holographic metasurface panel includes a periodically arrayed liquid crystal holographic metasurface unit, which includes an upper glass substrate, a patch electrode, a liquid crystal layer, a common ground electrode, and a lower glass substrate stacked sequentially from top to bottom.

[0010] Furthermore, the ground of the monopole antenna feed is a common ground electrode, and the height of the monopole antenna feed is adjusted by excitation through a coaxial connector located on the back of the common ground electrode to adjust the operating frequency.

[0011] Furthermore, the antenna beam direction 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.

[0012] Furthermore, the antenna polarization state 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.

[0013] Furthermore, in each liquid crystal holographic metasurface panel, the common ground electrode of all liquid crystal holographic metasurface units is subjected to the same voltage, while the patch electrodes are subjected to independent voltages.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] This invention utilizes liquid crystal materials to realize a holographic antenna, enabling continuous control and more effectively achieving beam scanning and polarization switching performance. The antenna control boasts low power consumption, easy integration, and a simple bias network, resulting in better performance in high-frequency applications. By setting the dielectric constant of the liquid crystal, independent control of beam pointing and polarization can be achieved simultaneously, resulting in strong antenna reconfiguration capabilities and a wide range of applications. Employing mature glass-plate encapsulation technology for liquid crystals, and avoiding a central opening in the liquid crystal panel through multi-plate splicing, it offers excellent airtightness, stability, and fabrication feasibility. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of the liquid crystal holographic metasurface antenna in an embodiment of the present invention;

[0017] Figure 2(a) is a top view of the liquid crystal holographic metasurface splicing structure in an embodiment of the present invention;

[0018] Figure 2(b) is a top view of another liquid crystal holographic metasurface splicing structure in an embodiment of the present invention;

[0019] Figure 3 This is a three-dimensional structural diagram of the monopole antenna feed source in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the reflection coefficient of the monopole antenna feed in an embodiment of the present invention;

[0021] Figure 5 This is a three-dimensional structural diagram of a single liquid crystal holographic metasurface panel in an embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the three-dimensional structure of the liquid crystal holographic metasurface unit in an embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the surface impedance of the liquid crystal holographic metasurface unit as a function of the liquid crystal constant in an embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to the vertical polarization beam pointing to 0° during beam scanning in an embodiment of the present invention;

[0025] Figure 9 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a vertically polarized beam pointing at 15° during beam scanning in an embodiment of the present invention;

[0026] Figure 10 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a vertically polarized beam pointing at 30° during beam scanning in an embodiment of the present invention;

[0027] Figure 11 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a vertically polarized beam pointing at 45° during beam scanning in an embodiment of the present invention;

[0028] Figure 12 This 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;

[0029] Figure 13 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a vertical polarization beam pointing at 30° during polarization switching in an embodiment of the present invention;

[0030] Figure 14 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a horizontal polarization beam pointing at 30° during polarization switching in an embodiment of the present invention;

[0031] Figure 15 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a left-hand circularly polarized beam pointing at 30° during polarization switching in an embodiment of the present invention;

[0032] Figure 16 This is a schematic diagram of the liquid crystal dielectric constant distribution corresponding to a right-hand circularly polarized beam pointing at 30° during polarization switching in an embodiment of the present invention;

[0033] Figure 17This 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.

[0034] The components are: 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 Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] like Figure 1 As shown, this invention proposes a liquid crystal holographic metasurface antenna structure, comprising: a monopole antenna feed 1 and a liquid crystal holographic metasurface panel 2. To ensure the feasibility of antenna polarization switching and maintain consistent beam scanning performance in both forward and reverse directions, one necessary condition is that the monopole antenna feed 1 is located at the center of the entire liquid crystal holographic metasurface antenna structure. Considering manufacturing processes, the liquid crystal holographic metasurface panel 2 adopts a double-layer glass substrate encapsulation design. The fabrication of a central opening in the liquid crystal panel is challenging. To improve fabrication feasibility, Q-block liquid crystal holographic metasurface panels 2 are spliced ​​together, where Q≥3, to avoid openings in the panel and achieve central placement of the feed.

[0038] Figures 2(a) and 2(b) illustrate the schematic diagram of the splicing structure of the monopole antenna feed 1 and the liquid crystal holographic metasurface panel 2. Figure 2(a) corresponds to Q=3, and Figure 2(b) corresponds to Q=4. As mentioned earlier, as long as Q liquid crystal holographic metasurface panels 2 can be spliced ​​in a point-contact or surface-contact manner to form a position with a central hole for placing the monopole antenna feed 1, the specific antenna structure design is described below using Q=4 as an example. The length of a single liquid crystal panel is 42mm and the width is 40mm. Four liquid crystal holographic metasurface panels 2 are spliced ​​sequentially in a staggered manner with a stagger width of 2mm. Through splicing, a square slot with a length of 2mm and a width of 2mm is generated in the center. The overall length and width of the liquid crystal holographic metasurface antenna structure are 82mm and 82mm respectively.

[0039] like Figure 3The figure shown is a three-dimensional structural schematic diagram of the monopole antenna feed 1 in this invention, with a height of 2.5 mm and a diameter of 1 mm.

[0040] like Figure 4 The diagram shown is a schematic of the reflection coefficient of the monopole antenna feed 1 in this invention. The operating bandwidth of the monopole antenna feed 1 is 43.77%, and it has good impedance matching at the center frequency.

[0041] like Figure 5 The diagram shown is a three-dimensional structural schematic 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 single liquid crystal holographic metasurface panel 2 contains 21×20 liquid crystal holographic metasurface units 3.

[0042] like Figure 6 The diagram shows the structure of the liquid crystal holographic metasurface unit 3 in this embodiment of the invention, comprising, from top to bottom, 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. In this embodiment, the upper glass substrate 4 and the lower glass substrate 8 are made of Corning Eagle XG glass with a dielectric constant of 5.2, a thickness of 0.5 mm, and a size of 2 mm × 2 mm; the patch electrode 5 has a size of 1.8 mm × 1.8 mm; the dielectric constant of the liquid crystal layer 6 varies from 2.46 to 3.73, and the thickness of the liquid crystal layer 6 is 0.18 mm. 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 same voltage is applied to the common ground electrode 7 of all liquid crystal holographic metasurface units 3, while an independent voltage is applied to the patch electrode 5 of each liquid crystal holographic metasurface unit 3. This achieves independent voltage control for each liquid crystal holographic metasurface unit 3, and the dielectric constant of the liquid crystal is affected by the voltage magnitude, thus obtaining the ability to independently control the dielectric constant of the liquid crystal of each liquid crystal holographic metasurface unit 3. The ground of the monopole antenna feed 1 is also the common ground electrode 7. The operating frequency can be adjusted by adjusting the height of the monopole antenna feed 1 through excitation via the coaxial connector located on the back of the common ground electrode 7.

[0043] like Figure 7 The figure shows a schematic diagram of the surface impedance of the liquid crystal holographic metasurface unit 3 as a function of the liquid crystal constant in an embodiment of the present invention. The unit impedance variation curve characterizes 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 from 2.46 to 3.73, and the surface impedance modulation range of the liquid crystal holographic metasurface unit 3 is 186.68 J ohms to 269.80 J ohms.

[0044] Figures 8-12 The results show the liquid crystal dielectric distribution and gain pattern of the liquid crystal holographic metasurface antenna of the present invention when used for beam scanning.

[0045] like Figure 8 As shown, this is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to the vertical polarization 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0046] like Figure 9 The figure shown is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a vertically polarized beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0047] like Figure 10 The figure shown is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a vertically polarized beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0048] like Figure 11 The figure shown is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a vertically polarized beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0049] like Figure 12 The diagram shown is a schematic representation 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°, and the antenna polarization is fixed as vertical polarization. When the beam scanning angle is 0°, the peak beam gain is 15.96dB; when the beam scanning angle is 15°, the peak beam gain is 17.42dB; when the beam scanning angle is 30°, the peak beam gain is 15.20dB; and when the beam scanning angle is 45°, the peak beam gain is 17.11dB.

[0050] Figures 13-17 The results show the liquid crystal dielectric distribution and gain pattern of the liquid crystal holographic metasurface antenna used for polarization switching.

[0051] like Figure 13As shown, this is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a vertical polarization beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0052] like Figure 14 The figure shows a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a horizontal polarization beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0053] like Figure 15 As shown, this is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a left-hand circularly polarized beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0054] like Figure 16 The figure shown is a schematic diagram of the distribution of liquid crystal dielectric constant corresponding to a right-hand circularly polarized beam pointing at 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 central square is the location of the feed source. The range of liquid crystal dielectric constant variation is 2.46-3.73.

[0055] like Figure 17 The diagram shown illustrates the gain pattern of the liquid crystal holographic metasurface antenna during polarization switching in an embodiment of the present invention. The antenna polarization states are vertical polarization, horizontal polarization, left-hand circular polarization, and right-hand circular polarization, with the beam pointing angle fixed at 30°. When the polarization state is vertical, the gain of the main polarization component is 15.20 dB; when the polarization state is horizontal, the gain of the main polarization component is 14.40 dB; when the polarization state is vertical, the gain of the main polarization component is 16.16 dB; and when the polarization state is vertical, the gain of the main polarization component is 16.93 dB.

[0056] The liquid crystal holographic metasurface antenna in this embodiment of the invention has a simple liquid crystal control method, an easy-to-integrate feeding structure, can achieve beam scanning at a large angle, can switch between four polarization states (vertical polarization, horizontal polarization, left-hand circular polarization and right-hand circular polarization), and has high radiation gain.

[0057] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A liquid crystal holographic metasurface antenna, characterized in that, It includes a monopole antenna feed (1) and Q liquid crystal holographic metasurface panels (2), wherein, The Q liquid crystal holographic metasurface panels (2) are staggered and spliced ​​in a circumferential direction to create a slot at the center for placing the monopole antenna feed (1), Q≥3; Each liquid crystal holographic metasurface panel (2) includes liquid crystal holographic metasurface units (3) arranged in a periodic array. Each liquid crystal holographic metasurface unit (3) 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 from top to bottom. The common ground electrode (7) of all liquid crystal holographic metasurface units (3) is subjected to the same voltage, while the patch electrode (5) is subjected to an independent voltage. The liquid crystal holographic metasurface panel (2) achieves independent control of the liquid crystal dielectric constant of each liquid crystal holographic metasurface unit (3) by independently controlling the voltage of the patch electrode (5) of each liquid crystal holographic metasurface unit (3), thereby simultaneously achieving independent control of beam pointing and polarization state.

2. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that, The ground of the monopole antenna feed (1) is the common ground electrode (7). The height of the monopole antenna feed (1) is adjusted to regulate the operating frequency by excitation through the 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 dielectric constant of the liquid crystal, and beam scanning is achieved by setting the distribution of the dielectric constant of the liquid crystal layer (6).

4. The liquid crystal holographic metasurface antenna according to claim 1, characterized in that, The antenna polarization state 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 (6).

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