Dual-band terahertz liquid crystal phase shifter for phased antenna and manufacturing method of dual-band terahertz liquid crystal phase shifter

Abstract

The invention relates to the technical field of terahertz wave regulation and control, in particular to a dual-band terahertz liquid crystal phase shifter for a phased antenna and a manufacturing method, and the dual-band terahertz liquid crystal phase shifter comprises an upper dielectric substrate and a lower dielectric substrate; a liquid crystal layer is arranged between the upper dielectric substrate and the lower dielectric substrate; a resonant structure is arranged between the upper dielectric substrate and the liquid crystal layer; a metal layer is arranged between the liquid crystal layer and the lower dielectric substrate; the resonant structure comprises a patch unit; the resonant structure and the metal layer are connected with a power supply; voltage is applied to the resonant structure and the metal layer to control the deflection state of liquid crystal molecules in the region so as to regulate and control the phase parameter of the terahertz wave; different phase shifts are achieved by applying different voltages.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz wave regulation and control, and in particular to a dual-band terahertz liquid crystal phase shifter for a phased antenna and a manufacturing method thereof. Background Art

[0002] Liquid crystal is an organic compound between solid and liquid. Due to its special electromagnetic properties, it is widely used in electromagnetic wave control devices. Liquid crystal molecules have both liquid fluidity and crystal anisotropy, so they are widely used in electromagnetic wave control devices. Under the action of an external electric field, nematic liquid crystal molecules are easily deflected, and their dielectric properties will change accordingly; so electromagnetic waves can be controlled by applying power; current single-frequency antennas can no longer meet the needs of modern communications, and dual-frequency antennas have become a better choice because they can cover two frequency bands at the same time; however, the operating frequency of traditional dual-frequency antennas is fixed and cannot be controlled once the design is completed; compared with radio frequency and microwave bands, terahertz waves have rich spectrum resources, stronger directionality and higher transmission rate, which makes them show great potential in fields such as communications and radar; existing phased antennas cannot achieve phase control of dual-frequency bands of terahertz waves.

[0003] After searching, the applicant found that the Chinese patent document with publication number 110739537A disclosed a high-density and high-integration millimeter-wave tile-type phased array antenna T component on January 31, 2020, aiming to provide a T component design scheme with reliable performance, easy integration and low profile. The present invention is implemented by the following scheme: the RF signal is directly fed from the common end at the bottom of the lower cavity of the T component through the RF coaxial connector, and directly transitions to the T-junction. The single chip integrates the functions of power pre-amplification, power division network, amplitude and phase control, serial-to-parallel conversion, power management and digital control. The GaAs power amplifier chips corresponding to the number of channels are cascaded to form a multi-channel 2.5-dimensional heterogeneous scalable sub-array unit. The low-frequency signal network directly controls the single chip and GaAs power amplifier of the T component to realize the phase shift, amplitude attenuation and power amplification of the multi-channel signals. The processed signal is sent to the filtering function layer of the multi-layer circuit board at the upper end of the T component through the vertical interconnection structure of the coplanar waveguide to coaxial conversion. The filtered signal is finally sent to the microstrip patch antenna to transmit the RF signal; the device also cannot solve the above technical problems.

[0004] Therefore, in order to improve or solve at least one of the above problems, it is necessary to provide a dual-band terahertz liquid crystal phase shifter for a phased antenna and a manufacturing method thereof, which can realize phase control of a dual-band terahertz wave. Summary of the invention

[0005] The object of the present invention is to provide a dual-band terahertz liquid crystal phase shifter for a phased antenna and a manufacturing method thereof, which can realize phase control of dual-band terahertz waves.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a dual-band terahertz liquid crystal phase shifter for a phased antenna, comprising an upper dielectric substrate and a lower dielectric substrate; a liquid crystal layer is provided between the upper dielectric substrate and the lower dielectric substrate; a resonant structure is provided between the upper dielectric substrate and the liquid crystal layer; a metal layer is provided between the liquid crystal layer and the lower dielectric substrate; the resonant structure comprises a patch unit; and the resonant structure and the metal layer are both connected to a power supply.

[0007] The patch unit includes a first connecting patch and a second connecting patch; the first connecting patch and the second connecting patch are cross-arranged; an upper patch is provided at one end of the first connecting patch, and a lower patch is provided at the other end of the first connecting patch; a left patch is provided at one end of the second connecting patch, and a right patch is provided at the other end of the second connecting patch.

[0008] The upper patch and the lower patch both include a first connecting section; the first connecting section is connected to the first connecting patch; a first long arm is provided at one end of the first connecting section, and a first short arm is provided at the other end of the first connecting section; the left patch and the right patch both include a second connecting section; the second connecting section is connected to the second connecting patch; a second long arm is connected to one end of the second connecting section, and a second short arm is connected to the other end of the second connecting section.

[0009] The upper patch and the lower patch are arranged rotationally symmetrically according to the intersection of the first connecting patch and the second connecting patch; the left patch and the right patch are arranged rotationally symmetrically according to the intersection of the first connecting patch and the second connecting patch; and a plurality of the patch units are arranged periodically on the upper dielectric substrate.

[0010] The metal layer includes a metal patch; the metal patch is arranged on the lower dielectric substrate.

[0011] A polyimide film is provided on the side of the resonant structure close to the liquid crystal layer; a polyimide film is provided on the side of the metal layer close to the liquid crystal layer; and polystyrene microspheres are provided at both ends of the liquid crystal layer.

[0012] The patch unit and the metal patch are both copper patches; the liquid crystal layer is nematic liquid crystal; the upper dielectric substrate and the lower dielectric substrate are both quartz plates.

[0013] A method for manufacturing the dual-band terahertz liquid crystal phase shifter for a phased antenna comprises the following steps:

[0014] S1: copper is plated on the upper dielectric substrate and the copper is etched into a resonant structure;

[0015] S2: copper is plated on the lower dielectric substrate and the copper is etched into a metal layer;

[0016] S3: filling a liquid crystal layer between the resonant structure and the metal layer; connecting the resonant structure and the metal layer to a power source.

[0017] In S1: the first connection patch and the second connection patch are arranged vertically; the upper patch and the lower patch are arranged 180° rotationally symmetrically according to the intersection of the first connection patch and the second connection patch; the left patch and the right patch are arranged 180° rotationally symmetrically according to the intersection of the first connection patch and the second connection patch; a plurality of patch units are arranged periodically on the upper dielectric substrate, the period length is P, and the number of periods is a positive integer greater than 1;

[0018] In S2, a metal patch is plated on the lower dielectric substrate; the left and right sides of the metal patch are indented by a certain interval.

[0019] In S3, a liquid crystal layer is filled between the resonant structure and the metal layer, and a small amount of polystyrene microspheres are respectively arranged at both ends of the liquid crystal layer; the thickness of the liquid crystal layer is controlled by the diameter of the polystyrene microspheres; a polyimide film is spin-coated between the resonant structure and the metal layer and the liquid crystal layer; the polyimide film and the liquid crystal layer are frictionally oriented; the liquid crystal layer is sealed with epoxy resin; the upper dielectric substrate and the resonant structure are combined and bonded to the combination of the metal layer and the lower dielectric substrate.

[0020] The beneficial effects of this application are:

[0021] The present application provides a dual-band terahertz liquid crystal phase shifter structure for a phased antenna, which applies voltage to a resonant structure and a metal layer, and applies an electric field to a liquid crystal layer between the resonant structure and the metal layer, causing the liquid crystal molecules to deflect, thereby changing the dielectric constant of the liquid crystal in the area, thereby achieving regulation of the phase parameters of two-band terahertz waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 Schematic diagram of the structure of the dual-band terahertz liquid crystal phase shifter used for phased antenna.

[0024] Figure 2 Schematic diagram of the structure of the patch unit of the dual-band terahertz liquid crystal phase shifter used for phased antenna.

[0025] Figure 3Schematic diagram of the structure of the metal layer of the dual-band terahertz liquid crystal phase shifter used for phased antenna.

[0026] Figure 4 This is a cross-sectional view of the dual-band terahertz liquid crystal phase shifter used for phased antenna when it is not powered on.

[0027] Figure 5 This is a cross-sectional view of the dual-band terahertz liquid crystal phase shifter used for phased antenna when full bias voltage is applied.

[0028] Figure 6 This is a simulated phase shift dot-line diagram of the dual-band terahertz liquid crystal phase shifter used for phased antenna at 230-290GHz in the initial state and full-bias state of the liquid crystal.

[0029] Figure 7 This is a simulated phase shift dot-line diagram of the dual-band terahertz liquid crystal phase shifter used for phased antenna at 320-370GHz in the initial state and full-bias state of the liquid crystal.

[0030] Figure 8 This is a simulated phase shift dot-line diagram of the dual-band terahertz liquid crystal phase shifter used for phased antenna at different dielectric constants at 230-290GHz.

[0031] Fig. 9 This is a simulated phase shift dot-line diagram of the dual-band terahertz liquid crystal phase shifter used for phased antenna at different dielectric constants at 320-370GHz.

[0032] The marks in the above figure are:

[0033] The markings in the figure are:

[0034] 1. Upper dielectric substrate,

[0035] 2. Lower dielectric substrate,

[0036] 3. Liquid crystal layer,

[0037] 4. Resonant structure,

[0038] 5. Metal layer, 501, metal patch,

[0039] 6. First connecting patch, 601. Upper patch, 602. Lower patch, 603. First connecting section, 604. First long arm, 605. First short arm,

[0040] 7. Second connecting patch, 701. Left patch, 702. Right patch, 703. Second connecting section, 704. Second long arm, 705. Second short arm. DETAILED DESCRIPTION

[0041] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and facilitating their implementation.

[0042] Figure 1 The dual-band terahertz liquid crystal phase shifter for a phased antenna shown includes an upper dielectric substrate 1 and a lower dielectric substrate 2; a liquid crystal layer 3 is provided between the upper dielectric substrate 1 and the lower dielectric substrate 2; a resonant structure 4 is provided between the upper dielectric substrate 1 and the liquid crystal layer 3; a metal layer 5 is provided between the liquid crystal layer 3 and the lower dielectric substrate 2; the resonant structure 4 includes a patch unit; the resonant structure 4 and the metal layer 5 are both connected to a power supply; the resonant structure 4 and the metal layer 5 are used as resonant structures and also as electrodes for deflecting the liquid crystal.

[0043] By applying voltage to the resonant structure 4 and the metal layer 5, an electric field is applied to the liquid crystal layer 3 between the resonant structure 4 and the metal layer 5 to cause the liquid crystal molecules to deflect, thereby changing the dielectric constant of the liquid crystal in the area, and then realizing the regulation of the phase parameters of the two-band terahertz waves; the liquid crystal phase shifter is realized by applying different voltages to the resonant structure 4 and the metal layer 5 to adjust the phase change.

[0044] like Figure 2 The patch unit shown includes a first connecting patch 6 and a second connecting patch 7; the first connecting patch 6 and the second connecting patch 7 are arranged crosswise; an upper patch 601 is provided at one end of the first connecting patch 6, and a lower patch 602 is provided at the other end of the first connecting patch 6; a left patch 701 is provided at one end of the second connecting patch 7, and a right patch 702 is provided at the other end of the second connecting patch 7.

[0045] The resonant structure 4 includes multiple patch units; the patch unit can be a windmill-shaped patch unit 2.1; the first connecting patch 6 and the second connecting patch 7 are fixedly connected and are a cross-shaped structure; the upper patch 601 and the lower patch 602 have the same structure and are fixedly connected to the two ends of the first connecting patch 6; the left patch 701 and the right patch 702 have the same structure and are fixedly connected to the two ends of the second connecting patch 7.

[0046] The upper patch 601 and the lower patch 602 both include a first connecting section 603; the first connecting section 603 is connected to the first connecting patch 6; a first long arm 604 is provided at one end of the first connecting section 603, and a first short arm 605 is provided at the other end of the first connecting section 603; the left patch 701 and the right patch 702 both include a second connecting section 703; the second connecting section 703 is connected to the second connecting patch 7; a second long arm 704 is connected to one end of the second connecting section 703, and a second short arm 705 is connected to the other end of the second connecting section 703.

[0047] In this embodiment, the length of the first connecting section 603 is L1=180μm, and the width is W1=43μm; the length of the first long arm 604 is L3=58μm, and the width is W3=95μm; the length of the first short arm 605 is L2=18μm, and the width is W2=24μm; the upper patch 601 and the lower patch 602 are each indented by Y=6μm; the length of the second connecting section 703 is L1r=150μm, and the width is W1r=58μm; the length of the second long arm 704 is L3r=13μm, and the width is W3r=100μm; the length of the second short arm 705 is L2r=33μm, and the width is W2r=22μm; the length of the first connecting patch 6 is L4=13μm; and the width of the second connecting patch 7 is W4=13μm.

[0048] The upper patch 601 and the lower patch 602 are rotationally symmetrically arranged according to the intersection of the first connection patch 6 and the second connection patch 7; the left patch 701 and the right patch 702 are rotationally symmetrically arranged according to the intersection of the first connection patch 6 and the second connection patch 7; and multiple patch units are periodically arranged on the upper dielectric substrate 1.

[0049] The resonant structure 4 is formed by periodically arranging the windmill-shaped patch units 2.1, the period length is P, and the number of periods is a positive integer greater than 1.

[0050] like Figure 3 The metal layer 5 shown includes a metal patch 501 ; the metal patch 501 is disposed on the lower dielectric substrate 2 .

[0051] The metal patch 501 is a rectangular metal patch 501, plated on a quartz plate with a period of P = 450μm; the left and right indents of the metal patch 501 are X = 6μm, and the width is P = 450μm; multiple metal patches 501 are arranged at equal intervals on the lower dielectric substrate 2, similar to the structure of a grating, and the phase shifter can be controlled.

[0052] A polyimide film is provided on the side of the resonant structure 4 close to the liquid crystal layer 3 ; a polyimide film is provided on the side of the metal layer 5 close to the liquid crystal layer 3 ; polystyrene microspheres are provided at both ends of the liquid crystal layer 3 .

[0053] The liquid crystal type of the liquid crystal layer 3 is nematic liquid crystal, and the thickness is controlled by the diameter of a small amount of polystyrene microspheres distributed at the edge of the liquid crystal layer 3; the diameter of the polystyrene microspheres in this embodiment is 40 μm, so the thickness of the liquid crystal layer 3 can be controlled to be 40 μm; a layer of polyimide film is spin-coated on the surface of the resonant structure 4 and the metal layer 5, and an initial horizontal orientation is provided to the liquid crystal through friction orientation.

[0054] The patch unit and the metal patch 501 are both copper patches; the liquid crystal layer 3 is a nematic liquid crystal; the upper dielectric substrate 1 and the lower dielectric substrate 2 are both quartz plates.

[0055] The resonant structure 4 and the metal layer 5 are both made of copper with a thickness of 0.5 μm; the upper dielectric substrate 1 and the lower dielectric substrate 2 are both made of quartz glass with a thickness of 315 μm; a liquid crystal layer 3 is filled between the resonant structure 4 and the metal layer 5 with a thickness of 40 μm.

[0056] A method for manufacturing a dual-band terahertz liquid crystal phase shifter for a phased antenna comprises the following steps:

[0057] S1: copper is plated on the upper dielectric substrate 1, and a resonant structure 4 is processed by ultraviolet lithography;

[0058] S2: copper is plated on the lower dielectric substrate 2, and a metal layer 5 is processed by ultraviolet lithography;

[0059] S3: filling the liquid crystal layer 3 between the resonance structure 4 and the metal layer 5; connecting the resonance structure 4 and the metal layer 5 to a power source.

[0060] In S1, copper is first plated on the upper dielectric substrate 1, and then the copper of the upper dielectric substrate 1 is processed into a resonant structure 4; in S2, copper is first plated on the lower dielectric substrate 2, and then the copper of the lower dielectric substrate 2 is processed into a metal layer 5; S3: a liquid crystal layer 3 is filled between the resonant structure 4 and the metal layer 5; the resonant structure 4 and the metal layer 5 are connected to a power source, so that a voltage is applied to the resonant structure 4 and the metal layer 5.

[0061] In S1: the first connection patch 6 and the second connection patch 7 are arranged vertically; the upper patch 601 and the lower patch 602 are arranged 180° rotationally symmetrically according to the intersection of the first connection patch 6 and the second connection patch 7; the left patch 701 and the right patch 702 are arranged 180° rotationally symmetrically according to the intersection of the first connection patch 6 and the second connection patch 7; a plurality of patch units are arranged periodically on the upper dielectric substrate 1, the period length is P, and the number of periods is a positive integer greater than 1;

[0062] In S2, a metal patch 501 is plated on the lower dielectric substrate 2; the left and right sides of the metal patch 501 are indented by a certain interval.

[0063] In S3, a liquid crystal layer 3 is filled between the resonant structure 4 and the metal layer 5, and a small amount of polystyrene microspheres are respectively arranged at both ends of the liquid crystal layer 3; the thickness of the liquid crystal layer 3 is controlled by the diameter of the polystyrene microspheres; a polyimide film is spin-coated between the resonant structure 4 and the metal layer 5 and the liquid crystal layer 3; the polyimide film and the liquid crystal layer 3 are frictionally oriented; the liquid crystal layer 3 is sealed with epoxy resin; the copper plated on the upper dielectric substrate 1 is processed into the resonant structure 4, and the copper plated on the lower dielectric substrate 2 is processed into the metal layer 5.

[0064] The specific workflow of the present invention is as follows:

[0065] When a y-polarized electromagnetic wave is incident in the Z direction, the phase of the reflected wave will change when the deflection state of the liquid crystal molecules is changed by voltage; the metal layer 5 in the phase shifter unit is used as the basis; when voltage is applied to the metal layer 5 and the resonant structure 4 above, a vertical electric field exists in the region, and the biased vertical electric field makes the long axis direction of the liquid crystal molecules in the region parallel to the electric field direction; when the region is not powered, the long axis direction of the liquid crystal molecules is perpendicular to the electric field direction. When the resonant structure 4 and the metal layer 5 are in the unpowered state, the dielectric constant of the liquid crystal is the smallest, and the side cross-section of the dual-band liquid crystal-based terahertz phase shifter is shown in FIG. Figure 4 When the full bias voltage is applied to the resonant structure 4 and the metal layer 5, the dielectric constant of the liquid crystal is the largest, and the side cross-sectional view of the dual-band liquid crystal-based terahertz phase shifter is as shown. Figure 5 As shown, at this time, the liquid crystal molecules become vertical due to the influence of the electric field.

[0066] In this embodiment, the phase shift curve of the phase shifter is as follows: Figure 6 As shown, it can be seen that when the dielectric constant is from ε = 2.47 to 3.37, the phase shift of the dual-band liquid crystal phase shifter is greater than 180° between 254 GHz and 269 GHz, and the maximum phase shift is 264° at 261 GHz; Figure 7 As shown, when the dielectric constant increases from ε=2.47 to 3.31, the phase shift of the dual-band liquid crystal phase shifter is greater than 180° between 337 GHz and 355 GHz, and the maximum phase shift is 241° at 346 GHz; Figure 8 It is the simulated phase shift point-line diagram under different dielectric constants at 230-290GHz;

[0067] Fig. 9 It is a simulated phase shift point-line diagram under different dielectric constants at 320-370GHz.

[0068] The present application controls the deflection state of the liquid crystal molecules in the region by applying voltage to the resonant structure 4 and the metal layer 5 to achieve phase parameter regulation of the terahertz wave; different phase shifts are achieved by applying different voltages.

[0069] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A dual-band terahertz liquid crystal phase shifter for a phased antenna, characterized in that: The invention comprises an upper dielectric substrate (1) and a lower dielectric substrate (2); a liquid crystal layer (3) is provided between the upper dielectric substrate (1) and the lower dielectric substrate (2); a resonant structure (4) is provided between the upper dielectric substrate (1) and the liquid crystal layer (3); a metal layer (5) is provided between the liquid crystal layer (3) and the lower dielectric substrate (2); the resonant structure (4) comprises a patch unit; and the resonant structure (4) and the metal layer (5) are both connected to a power source.

2. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to claim 1, characterized in that: The patch unit comprises a first connecting patch (6) and a second connecting patch (7); the first connecting patch (6) and the second connecting patch (7) are arranged crosswise; an upper patch (601) is arranged at one end of the first connecting patch (6), and a lower patch (602) is arranged at the other end of the first connecting patch (6); a left patch (701) is arranged at one end of the second connecting patch (7), and a right patch (702) is arranged at the other end of the second connecting patch (7).

3. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to claim 2, characterized in that: The upper patch (601) and the lower patch (602) both include a first connecting section (603); the first connecting section (603) is connected to the first connecting patch (6); a first long arm (604) is provided at one end of the first connecting section (603), and a first short arm (605) is provided at the other end of the first connecting section (603); the left patch (701) and the right patch (702) both include a second connecting section (703); the second connecting section (703) is connected to the second connecting patch (7); one end of the second connecting section (703) is connected to the second long arm (704), and the other end of the second connecting section (703) is connected to the second short arm (705).

4. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to any one of claims 2 to 3, characterized in that: The upper patch (601) and the lower patch (602) are arranged rotationally symmetrically according to the intersection of the first connecting patch (6) and the second connecting patch (7); the left patch (701) and the right patch (702) are arranged rotationally symmetrically according to the intersection of the first connecting patch (6) and the second connecting patch (7); and a plurality of the patch units are arranged periodically on the upper dielectric substrate (1).

5. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to claim 4, characterized in that: The metal layer (5) comprises a metal patch (501); the metal patch (501) is arranged on the lower dielectric substrate (2).

6. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to claim 5, characterized in that: A polyimide film is provided on the side of the resonant structure (4) close to the liquid crystal layer (3); a polyimide film is provided on the side of the metal layer (5) close to the liquid crystal layer (3); and polystyrene microspheres are provided at both ends of the liquid crystal layer (3).

7. A dual-band terahertz liquid crystal phase shifter for a phased antenna according to any one of claims 5 to 6, characterized in that: The patch unit and the metal patch (501) are both copper patches; the liquid crystal layer (3) is nematic liquid crystal; and the upper dielectric substrate (1) and the lower dielectric substrate (2) are both quartz plates.

8. A method for manufacturing a dual-band terahertz liquid crystal phase shifter for a phased antenna according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: copper is plated on an upper dielectric substrate (1), and the copper is etched into a resonant structure (4); S2: copper is plated on the lower dielectric substrate (2), and the copper is etched into a metal layer (5); S3: filling a liquid crystal layer (3) between the resonant structure (4) and the metal layer (5); connecting the resonant structure (4) and the metal layer (5) to a power source.

9. The manufacturing method according to claim 8, characterized in that: In S1: the first connecting patch (6) and the second connecting patch (7) are arranged vertically; the upper patch (601) and the lower patch (602) are arranged 180° rotationally symmetrically according to the intersection of the first connecting patch (6) and the second connecting patch (7); the left patch (701) and the right patch (702) are arranged 180° rotationally symmetrically according to the intersection of the first connecting patch (6) and the second connecting patch (7); a plurality of patch units are arranged periodically on the upper dielectric substrate (1), the period length is P, and the number of periods is a positive integer greater than 1; In S2, a metal patch (501) is plated on the lower dielectric substrate (2); the left and right sides of the metal patch (501) are indented by a certain interval.

10. The manufacturing method according to claim 9, characterized in that: In the S3, a liquid crystal layer (3) is filled between the resonant structure (4) and the metal layer (5), and a small amount of polystyrene microspheres are respectively arranged at both ends of the liquid crystal layer (3); the thickness of the liquid crystal layer (3) is controlled by the diameter of the polystyrene microspheres; a polyimide film is spin-coated between the resonant structure (4) and the metal layer (5) and the liquid crystal layer (3); the polyimide film and the liquid crystal layer (3) are rubbing-oriented; the liquid crystal layer (3) is sealed with epoxy resin; the upper dielectric substrate (1) and the resonant structure (4) are combined and bonded to the combination of the metal layer (5) and the lower dielectric substrate (2).

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