Active dual-band liquid crystal array reflective structure

Abstract

The invention provides an active dual-band liquid crystal array reflective structure. The structure contains a first substrate layer, a first liquid crystal layer, and a second substrate layer. Each of the first substrate layer and the second substrate layer has four surface units, and components on different surface units are used to form a first reflective single cell unit and a second reflective single cell unit. When the first liquid crystal layer is not biased, the first reflective single cell unit can be used as a first reflective surface with a

Description

Technical Field

[0001] This invention relates to an active dual-frequency liquid crystal array reflective structure, and more particularly to a dual-frequency liquid crystal array reflective surface design that is easy to design, has dual-phase reconstruction, is easy to implement, and achieves the expected frequency band gain and directivity at both receiving ends. Prior Technology

[0002] Early array reflectors were mainly used in radio and radar systems, employing geometric structures and electrode units to achieve signal reflection and focusing.

[0003] The basic function of array reflectors is to control the propagation path of electromagnetic waves through a series of reflective units, thereby achieving signal enhancement, direction control, and beamforming. However, due to the high cost of curved surface construction in terms of design and cost-effectiveness, they are gradually being replaced by planar array reflector surfaces. These reflective units can have fixed electrode units or adjustable ones (by adding lumped elements such as PIN-Diodes) to adapt to different application requirements.

[0004] With the advancement of technology, array reflectors have been widely used in fields such as communications, radar, satellites, and wireless transmission, playing a vital role in communication and information dissemination in modern society. Their impact on society is mainly reflected in promoting the development and application of communication technologies and improving communication quality and efficiency.

[0005] For example, in wireless communication, array reflectors can effectively increase signal coverage and transmission rates, thereby meeting people's growing communication needs. In radar systems, array reflectors can improve the accuracy of target detection and tracking, which is of great significance in the defense and aerospace fields.

[0006] Among various types of array reflectors, dual-band liquid crystal array reflectors possess multifunctional characteristics, enabling operation and independent control on two different frequency bands. The ever-increasing demand for multifunctional and efficient antennas in modern communication and radar systems has driven the development of dual-band reflector arrays.

[0007] These reflective surfaces can operate at multiple frequencies, thus enhancing their applicability in various scenarios such as satellite communications, wireless communications, and remote sensing. The integration of liquid crystal technology further enhances the adaptability of the reflective array by allowing dynamic control of the phase response of the reflective units.

[0008] This paper proposes a dual-band liquid crystal array reflective surface structure, which can modulate different dielectric parameters of the entire liquid crystal layer to achieve the expected gain and directivity at two fixed receiving ends.

[0009] The structure proposed in this case simplifies the phase control of the independent control unit and improves and optimizes the circuit design and manufacturing cost. Although its performance is worse than that of beam scanning, the fixed dual-band reflection phase makes control and calculation relatively easy, and the appropriate reflection angle can have a wider range of applications in the living environment. In addition, the selectivity of the frequency band is also a major feature. Compared with a general dual-band reflector, the liquid crystal can adjust the passage of a certain band in real time, rather than reflecting any frequency band at all times. In the environment with extensive coverage of 5G and LOR communication, this selective design can ensure the confidentiality of any frequency band.

[0010] Compared to conventional technologies, the structure of this invention suffers from higher cell losses due to individual control of the liquid crystal layer cells, failing to meet low-loss requirements. Furthermore, the control of bias voltage variations requires extreme precision, making design difficult. In practical operation, external factors and errors significantly reduce the success rate, and achieving phase reconstruction of the reflection is also challenging. Therefore, this invention offers advantages such as ease of design, dual-phase reconstruction, ease of implementation, and the achievement of the desired frequency band gain and directivity at both receivers. Thus, this invention represents the optimal solution. Summary of the Invention

[0011] An active dual-frequency liquid crystal array reflective structure includes: a first substrate layer having a first upper surface and a first lower surface; a second substrate layer having a second upper surface and a second lower surface; a first liquid crystal layer stacked between the first substrate layer and the second substrate layer; and a plurality of first surface units arranged in an array on the first upper surface, each first surface unit having four first surface frame-shaped patches and one first surface cross-shaped patch, wherein each first surface frame-shaped patch has a first surface rectangular patch inside. Several second surface units are arranged in an array on the first lower surface. Each second surface unit has four tree-shaped patches, with any two tree-shaped patches connected together. Each tree-shaped patch has a first conductive portion and three second conductive portions, with the three parallel second conductive portions connected in series with the first conductive portion. The first conductive portion extends along a first direction, and the second conductive portions extend along a second direction, which are different from each other. Several third surface units are arranged in an array. Arranged on the second upper surface, each third surface unit has four third surface rectangular patches, and the edges of each third surface rectangular patch are connected by four third surface metal lines; several fourth surface units are arranged in an array on the second lower surface, each fourth surface unit being a fourth surface rectangular patch; wherein, the first surface frame patch, the first surface rectangular patch, the first substrate layer, the tree-shaped patch, the first liquid crystal layer, the third surface rectangular patch, and the four third surface metal lines connected to the edges of the third surface rectangular patch are... The fourth surface unit forms a first reflective unit cell. When no bias voltage is applied to the first liquid crystal layer, the center operating frequency of the first reflective unit cell is between 27 and 29 GHz. The first surface cross-shaped patch, the first substrate layer, the second surface unit, the first liquid crystal layer, the third surface unit, and the fourth surface unit form a second reflective unit cell. When an electromagnetic wave is incident on the first liquid crystal layer after a bias voltage is applied, the center operating frequency of the second reflective unit cell is between 11 and 13 GHz.

[0012] More specifically, each set of four first surface frame-shaped patches is arranged around the first surface cross-shaped patch, and there is a first surface rectangular slit between the first surface frame-shaped patch and the first surface rectangular patch.

[0013] More specifically, the three second conductive parts are arranged in ascending order of length and connected in series to the first conductive part. When any two tree-shaped patches are connected, the second conductive part with the shortest length of any tree-shaped patch is connected to the second conductive part with the longest length of the other tree-shaped patch.

[0014] More specifically, each of the four rectangular patches on the third surface is surrounded by a cross-shaped opening on the third surface metal line.

[0015] More specifically, the first surface unit, the second surface unit, the third surface unit, and the fourth surface unit are formed of metal.

[0016] More specifically, before and after applying a bias voltage to the first liquid crystal layer, the dielectric constant of the first liquid crystal layer is 2.55~3.76, and the tangent loss is 0.004~0.006.

[0017] More specifically, the length and width of the first surface frame patch are 1~3.8mm, and the length and width of the first surface rectangular patch are 0.4~1.52mm.

[0018] More specifically, the first surface cross-shaped patch has a first longitudinal portion and a first transverse portion, the length of which is 2~11mm.

[0019] More specifically, when the first liquid crystal layer is not biased, the first reflective unit cell can be used as a first reflective surface when the center operating frequency is between 27 and 29 GHz; while when the first liquid crystal layer is biased, the second reflective unit cell can be used as a second reflective surface when the center operating frequency is between 11 and 13 GHz. Simple Explanation of the Diagram

[0020] [Figure 1A] is a schematic diagram of the multi-layer structure of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 1B] is a schematic cross-sectional view of the multilayer structure of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 2A] is a schematic diagram of the single-cell design of the first surface unit of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 2B] is a schematic diagram of the single-cell design of the second surface unit of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 2C] is a schematic diagram of the single-cell design of the third surface unit of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 2D] is a schematic diagram of the single-cell design of the fourth surface unit of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 3A] is a schematic diagram of the structure of the first reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 3B] is a schematic diagram of the phase relationship between the 28GHz patch cell of the first reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 3C] is a schematic diagram showing the relationship between the variation of the 28GHz patch cell of the first reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention and the reflectivity. [Figure 4A] is a schematic diagram of the structure of the second reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 4B] is a schematic diagram of the phase relationship between the 12GHz patch cell of the second reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 4C] is a schematic diagram showing the relationship between the variation of the 12GHz patch cell of the second reflective unit cell of the active dual-frequency liquid crystal array reflective structure of the present invention and the reflectivity. [Figure 5A] is a schematic diagram of the 28GHz surface array phase distribution of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 5B] is a schematic diagram of the 12GHz surface array phase distribution of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 6A] is a polar coordinate diagram of the total gain radiation field of the reflective surface of the liquid crystal array in the 28GHz band, which is the first embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 6B] is a two-dimensional diagram of the total gain radiation field pattern of the reflective surface of the liquid crystal array in the 28GHz band, which is the first embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 7A] is a polar coordinate diagram of the gain radiation field of the reflective surface of the 28GHz band liquid crystal array in the second embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 7B] is a two-dimensional diagram of the gain radiation field pattern of the reflective surface of the 28GHz band liquid crystal array of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 8A] is a 28GHz normalized gain polar coordinate diagram of the third embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 8B] is a two-dimensional diagram of the 28GHz normalized gain of the third embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 9A] is a polar coordinate diagram of the total gain radiation field of the reflective surface of the 12GHz band liquid crystal array in the fourth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 9B] is a two-dimensional diagram of the total gain radiation field pattern of the 12GHz band liquid crystal array reflective surface of the fourth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 10A] is a polar coordinate diagram of the gain radiation field of the reflective surface of the 12GHz band liquid crystal array in the fifth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 10B] is a two-dimensional diagram of the gain radiation field pattern of the reflective surface of the 12GHz band liquid crystal array in the fifth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 11A] is a 12GHz normalized gain polar coordinate diagram of the sixth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. [Figure 11B] is a two-dimensional diagram of the 12GHz normalized gain of the sixth embodiment of the active dual-frequency liquid crystal array reflective structure of the present invention. Implementation

[0021] Other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the accompanying drawings.

[0022] Please refer to Figures 1A and 1B, which are schematic diagrams and cross-sectional views of the multilayer structure of the active dual-frequency liquid crystal array reflective structure. As shown in the figures, the active dual-frequency liquid crystal array reflective structure is mainly designed as a two-layer, four-sided circuit board. The active dual-frequency liquid crystal array reflective structure includes a first substrate layer 1, a first liquid crystal layer 2, and a second substrate layer 3, wherein the first liquid crystal layer 2 is stacked and connected between the first substrate layer 1 and the second substrate layer 3.

[0023] The first substrate layer 1 and the second substrate layer 3 are high-frequency printed circuit boards (dielectric coefficient is 3.28~3.32, tangent loss is 0.002, the thickness of the first substrate layer 1 is 1.516~1.524mm, and the thickness of the second substrate layer 3 is 0.5065~0.5095mm), but this application is not limited to this type of circuit board.

[0024] The first liquid crystal layer 2, in this embodiment, uses JNC ZOC-A018XX liquid crystal material, with a thickness of 0.1 mm, a dielectric constant of 2.55~3.76, and a loss of 0.004~0.006.

[0025] In order to apply a bias voltage to the first liquid crystal layer 2, since the first liquid crystal layer 2 is sandwiched between the first substrate layer 1 and the second substrate layer 3, in actual industry implementation, both the first substrate layer 1 and the second substrate layer 3 are designed with a metal edge around their edges. Therefore, as long as a bias voltage is applied to the metal edges of the first substrate layer 1 and the second substrate layer 3 above and below the first liquid crystal layer 2, a voltage difference can be created across the entire liquid crystal layer. This feature is a well-known technical feature in the industry, so it is not specifically marked in the figure.

[0026] In the optimal implementation, the first liquid crystal layer 2 has a dielectric constant of 2.55 and a loss of 0.004 when the liquid crystal alignment direction is parallel to the electric field direction (before a bias voltage is applied to the first liquid crystal layer); and a dielectric constant of 3.76 and a loss of 0.006 when the liquid crystal alignment direction is perpendicular to the electric field (after a bias voltage is applied to the first liquid crystal layer). However, this invention is not limited to this type of liquid crystal material.

[0027] The first liquid crystal layer 2 has adjustable dielectric properties. By applying an external voltage, the rotation of the liquid crystal molecules can be changed, thereby changing its dielectric constant and altering the phase shift of the cells.

[0028] The first substrate layer 1 has a first upper surface 11 and a first lower surface 12.

[0029] The second substrate layer 3 has a second upper surface 31 and a second lower surface 32.

[0030] The first upper surface 11 forms a plurality of first surface units 111 arranged in an array, as shown in Figure 2A. Each first surface unit 111 has four first surface frame-shaped patches 1111 and a first surface cross-shaped patch 1114, and the first surface frame-shaped patch 1111 has a first surface rectangular patch 1112 inside.

[0031] Each set of four first surface frame-shaped patches is arranged around the first surface cross-shaped patch, and a first surface rectangular slit 1113 is provided between the first surface frame-shaped patch 1111 and the first surface rectangular patch 1112.

[0032] The first lower surface 12 is formed with a plurality of second surface units 121 arranged in an array, as shown in Figures 1A and 2B. Each second surface unit 121 has four tree-shaped patches 1211, wherein any two tree-shaped patches 1211 are connected. Each tree-shaped patch 1211 has a first conductive part 12111 and three second conductive parts 12112, 12113, and 12114, wherein the three parallel second conductive parts 12112, 12113, and 12114 are connected in series with the first conductive part 12111.

[0033] The three second conductive parts 12112, 12113, and 12114 are arranged in ascending order of length and connected in series to the first conductive part 12111. When any two tree-shaped patches 1211 are connected, the second conductive part 12112 with the shortest length of any tree-shaped patch 1211 is connected to the second conductive part 12114 with the longest length of the other tree-shaped patch 1211.

[0034] The first conductive part 12111 extends along a first direction (y direction), while the second conductive part extends along a second direction (x direction). The first direction and the second direction are not the same (the two directions are not parallel).

[0035] The second upper surface 31 is formed with a plurality of third surface units 311 arranged in an array, as shown in Figure 2C. Each third surface unit 311 has four third surface rectangular patches 3111, and the edges of each third surface rectangular patch 3111 are connected to four third surface metal lines 3112.

[0036] Each set of four rectangular patches 3111 on the third surface is surrounded by a cross-shaped opening 3113 on the third surface by the metal line 3112 on the third surface.

[0037] The second lower surface 32 is formed with a plurality of fourth surface units arranged in an array, as shown in Figure 2D. Each fourth surface unit is a fourth surface rectangular patch 321, which serves as a ground to ensure total reflection of electromagnetic waves.

[0038] The first, second, third, and fourth surface units are formed of a metallic material (e.g., copper foil with a thickness of 0.0017 mm).

[0039] The first substrate layer 1, the first liquid crystal layer 2, and the second substrate layer 3 are stacked to form the active dual-frequency liquid crystal array reflective structure.

[0040] As shown in Figure 2A, the first upper surface has multiple rectangular units (Dx is 12mm, Dy is 12mm), and the original metal layer (e.g., copper foil) of the first upper surface 11 is removed by etching to form multiple first surface units 111 on the first upper surface 11.

[0041] The surface design of the first surface unit 111 includes a first surface frame patch 1111, a first surface rectangular patch 1112, a first surface rectangular slit 1113, and a first surface cross-shaped patch 1114.

[0042] The length and width of the first surface outer frame patch 1111 are 1~3.8mm (A is 1~3.8mm).

[0043] The length and width of the first surface rectangular patch 1112 are 0.4~1.52mm.

[0044] The first surface cross-shaped patch 1114 has a first longitudinal portion and a first transverse portion, the length of which is 2~10mm (B is 2~11mm).

[0045] As shown in Figure 2B, the first lower surface 12 has multiple rectangular units (Dx is 12mm, Dy is 12mm), and the original metal layer (e.g., copper foil) of the first lower surface 12 is removed by etching to form multiple second surface units 121 on the first lower surface 12.

[0046] The surface design of the second surface unit 121 has four tree-shaped patches 1211, wherein each tree-shaped patch 1211 has a first conductive part 12111 and three second conductive parts 12112, 12113, and 12114.

[0047] The length of the first conductive part 12111 is 6mm (C is 6mm), and the width is 0.1mm; while the other dimensions are D=1.55~1.6mm, E=2.35~2.4mm, F=2.75~2.8mm, H=0.25~0.3mm, I=0.45~0.5mm, J=0.55~0.6mm, K=1.15~1.2mm, M=1.2~1.25mm, N=0.6~0.65mm, O=1.45~1.5mm, and G=0.05~0.1mm.

[0048] As shown in Figure 2C, the second upper surface 31 has multiple rectangular units (Dx is 12mm, Dy is 12mm), and the original metal layer (e.g., copper foil) of the second upper surface 31 is removed by etching to form multiple third surface units 311 on the second upper surface 31.

[0049] The third surface unit 311 has a third surface rectangular patch 3111, a third surface metal line 3112, and a third surface cross-shaped opening 3113.

[0050] The length and width of the rectangular patch 3111 on the third surface are 3.75~3.8mm (P).

[0051] The length of the third surface metal line 3112 is 5.95~6mm (Q), and the width is 0.05~0.1mm (G).

[0052] As shown in Figure 2D, the second lower surface 32 has multiple rectangular units (Dx is 12mm, Dy is 12mm), and the original metal layer (e.g., copper foil) of the second lower surface 32 is removed by etching to form multiple fourth surface units on the second lower surface 32.

[0053] The fourth surface unit is a fourth surface rectangular patch 321, and the length and width of the fourth surface rectangular patch are 1.15~1.2mm.

[0054] The 12GHz design in this case uses a symmetrical cross-shaped patch with a unit size of 12mm, while the 28GHz design uses a symmetrical double-ring patch with a unit size of 6mm.

[0055] After being assembled into an array, the number of 28GHz patch cells will be four times that of 12GHz patch cells, resulting in better beamforming. Furthermore, the maximum size of the 28GHz patch cells is designed to be 3.75~3.8mm. This is to prevent them from being connected to the 12GHz cells and thus to avoid mutual coupling.

[0056] In this design, the liquid crystal layer of the 28GHz unit is set to be unbiased, while the liquid crystal layer of the 12GHz unit is set to be biased. The dimensions of the other two components are approximately half the wavelength to prevent gate lobe interference.

[0057] The conductive patches (second surface unit 121 and third surface unit 311) in this case are arranged above and below the first liquid crystal layer 2, and their shapes are fixed.

[0058] The tree-shaped patch 1211 in this case is the upper patch of three parallel unequal electric dipole patches (second conductive parts 12112, 12113, 12114). These parallel unequal electric dipole patches are connected through bias lines (first conductive parts 12111) to ensure that the voltage on each unit is consistent.

[0059] The third surface unit of this invention has a square patch with four protruding corners (third surface rectangular patch 3111 and third surface metal line 3112) to ensure that each patch can be connected to each other.

[0060] As shown in Figure 3A, the first surface frame patch 1111, the first surface rectangular patch 1112, the first substrate layer 1, the tree-shaped patch 1211, the first liquid crystal layer 2, the third surface rectangular patch 3111 and the four third surface metal lines 3112 connecting the edges of the third surface rectangular patch 3111, and the fourth surface rectangular patch 321 of the fourth surface unit form a first reflective unit cell. When no bias voltage is applied to the first liquid crystal layer 2, the center operating frequency of the first reflective unit cell is between 27 and 29 GHz.

[0061] The center point of the first surface rectangular patch 1112 corresponds to the intersection of the first conductive part 12111 and the second conductive part 12113.

[0062] In response to different operating frequencies, the first surface frame-shaped patch 1111, the first surface rectangular patch 1112, and the tree-shaped patch 1211 correspond to different operating frequencies. Their design is less than 0.5 times the wavelength, but their internal detailed parameters need to be fine-tuned based on this wavelength, and the fine-tuning range is unlimited.

[0063] When the first liquid crystal layer 2 is not biased, the first reflective unit cell can be used as a first reflective surface when the center operating frequency is between 27 and 29 GHz.

[0064] As shown in Figure 3B, the incident wave in this case is assumed to be incident at 30 degrees, and the reflection phase at 28 GHz is shown in the figure. It can be seen that with the change of the double ring and cross patch, the corresponding liquid crystal dielectric constant has a phase change of more than 330 degrees.

[0065] As shown in Figure 3C, it can be observed that the S11 parameter remains below 2dB throughout the variation of the reflection coefficient at 28GHz across the patches (first surface frame patch 1111, first surface rectangular patch 1112), indicating very low loss. This indicates that the cell has near-perfect reflection.

[0066] As shown in Figure 4A, the first surface cross-shaped patch 1114, the first substrate layer 1, the second surface unit 121, the first liquid crystal layer 2, the third surface unit 311, and the fourth surface rectangular patch 321 of the fourth surface unit form a second reflective unit cell. When an electromagnetic wave is incident on the first liquid crystal layer 2 after a bias voltage is applied, the center operating frequency of the second reflective unit cell is between 11 and 13 GHz.

[0067] The center point of the first surface cross-shaped patch 1114 corresponds to the relative center position among the four tree-shaped patches 1211.

[0068] In response to different operating frequencies, the first surface cross-shaped patch 1114 and the tree-shaped patch 1211 correspond to different operating frequencies. Their design is less than 0.5 times the wavelength, but their internal detailed parameters need to be fine-tuned based on this wavelength, and the fine-tuning range is unlimited.

[0069] When a bias voltage is applied to the first liquid crystal layer 2, the second reflective unit cell can be used as a second reflective surface when the center operating frequency is between 11 and 13 GHz.

[0070] Since the voltages connected to the second surface unit 121 and the third surface unit 311 are different, there are different voltage differences between each unit. The magnitude of the electric field formed by the voltage difference is the main factor controlling the deflection of liquid crystal molecules.

[0071] The first liquid crystal layer 2 is situated between multiple second surface units 121 and multiple third surface units 311. The upper and lower conductive layers function to ensure uniform alignment of liquid crystal molecules when the electric field is zero (external voltage is zero). Therefore, when a bias voltage is applied starting from 0 volts, the liquid crystal molecules between units deflect, changing the dielectric constant and altering the electromagnetic wave reflection phase. Thus, by combining different bias voltages of the liquid crystal with the dual-frequency patch design of the first surface unit 111, the first frequency band is matched with a first bias voltage value (e.g., 0V), and the second frequency band is matched with a second bias voltage value (e.g., 10V). After calculating the incident and reflection angles, the size of the unit is adjusted to ensure that a specific frequency band is reflected at a specific position and can operate independently and be beamformed on two different frequency bands.

[0072] As shown in Figure 4B, the incident wave in this case is assumed to be incident at 30 degrees, and the reflection phase at 12 GHz is shown in the figure. It can be seen that with the change of the double ring and cross patch, the corresponding liquid crystal dielectric constant has a phase change of more than 330 degrees.

[0073] As shown in Figure 4C, it can be observed that the S11 parameter remains below 2dB throughout the variation of the reflection coefficient at 12GHz on the patch (first surface cross-shaped patch 1114), indicating very low loss. This indicates that the cell has near-perfect reflection.

[0074] As shown in Figure 5A, this is a simulated ideal phase distribution diagram of the present invention in the 28GHz frequency band. The grayscale color gradient represents the phase value from 0 to 360 degrees, and the x and y axes represent the number of units in the unit cell. As shown in Figure 5B, this is a simulated ideal phase distribution diagram of the present invention in the 12GHz frequency band. The grayscale color gradient represents the phase value from 0 to 360 degrees, and the x and y axes represent the number of units in the unit cell.

[0075] The phase required for simulating the ideal phase distribution (phase compensation) described above can be calculated using a formula. Those with prior knowledge in this field will certainly understand the calculation process, so it will not be elaborated further.

[0076] There are six implementations in this case, and the six implementations are described below.

[0077] The first implementation is described as follows: (1) As shown in Figure 6A, it is a polar coordinate diagram of the total gain radiation field of the reflective surface of the dual-band liquid crystal array. It can be seen that in the 28GHz band, the liquid crystal has a maximum gain of 25.34dB at the 0-degree reflection angle when it is not biased, and the -3dB beamwidth is 3 degrees. (2) As shown in Figure 6B, it is a two-dimensional diagram of the total gain radiation field, where the x-axis represents the change of theta in the spherical coordinates and the y-axis represents the total gain value.

[0078] The 28GHz band liquid crystal array reflector in this case uses a 300mm obliquely incident feed to simulate plane wave incident behavior. In practice, the feed will be incident on a parabolic reflector to reflect the plane wave to the designed reflector. In addition, the antenna used in this case is linearly polarized, and the -3dB beamwidths in the E-plane and H-plane are similar, which can achieve a highly directional pencil beam.

[0079] The second implementation is described as follows: (1) As shown in Figure 7A, it is a polar coordinate diagram used to evaluate the actual performance of the reflective array system and determine the amount of signal collected and reflected. (2) As shown in Figure 7B, it is a two-dimensional graph of the gain of the reflective surface of the dual-band liquid crystal array at 28GHz. (3) As shown in the figure above, the highest point is 25.2dB, which is less than 1dB different from the total gain. This is because the substrate loss is very low and the conductive patch is set as a perfect conductor (PEC).

[0080] The third implementation is explained as follows: (1) As shown in Figure 8A, it is a polar coordinate diagram of normalized gain. As can be seen from the figure, all the side lobes except the main beam are below -10dB. (2) As shown in Figure 8B, it is a two-dimensional graph of normalized gain. It can be seen that the sidelobes are more than 10 dB different from the main beam, and the sidelobe interference is low.

[0081] The fourth implementation is explained as follows: (1) As shown in Figure 9A, it is a polar coordinate diagram of the total gain radiation field of the reflective surface of the liquid crystal array in the 12GHz band. It can be seen that under the condition of liquid crystal bias, there is a maximum gain of 20.3dB at the 45-degree reflection angle and a beamwidth of 9.6 degrees at -3dB. (2) As shown in Figure 9B, it is a two-dimensional diagram of the total gain radiation field, where the x-axis represents the change of theta in the spherical coordinates and the y-axis represents the total gain value.

[0082] The 12GHz band liquid crystal array reflector in this case has a total gain of about 20dB, which is lower than that of the 28GHz band. This is because the reflection angle is larger and the number of units is smaller. In addition, the -3dB beamwidth of the feed is larger, and the required array surface is also larger. Since the computer performance is insufficient to run a larger array, the focus will be on achieving a reflector that meets the requirements, with high performance as a secondary consideration.

[0083] The fifth implementation is explained as follows: (1) As shown in Figure 10A, it is a polar coordinate diagram. (2) As shown in Figure 10B, a two-dimensional graph of the realized gain of the dual-band liquid crystal array reflective surface at 28 GHz is displayed. (3) As shown in the figure above, the actual performance of the reflective array system is evaluated and the amount of collected and reflected signals is determined. The highest point in the figure is 25.2 dB, which is less than 1 dB different from the total gain. This is because the substrate loss is very low and the conductive patch is set as a perfect conductor (PEC).

[0084] The sixth implementation is explained as follows: (1) As shown in Figure 11A, it is a polar coordinate diagram to depict the normalized gain. As can be seen from the figure, all the side lobes except the main beam are below -10dB. (2) As shown in Figure 11B, it is a two-dimensional graph of normalized gain, which shows that the sidelobe is more than 10 dB away from the main beam and the sidelobe interference is low.

[0085] The active dual-frequency liquid crystal array reflective structure provided by this invention has the following advantages compared with other conventional technologies: (1) This invention proposes a dual-band liquid crystal array reflective surface structure, wherein the structure can modulate different dielectric parameters of the entire liquid crystal layer to achieve the expected gain and directivity at two fixed receiving ends. (2) The dual-band liquid crystal array reflective surface of this case mainly utilizes the maximum horizontal and vertical dielectric constants of liquid crystal to enable the array to respond in two corresponding frequency bands. Unlike general dual-band array surfaces, the purpose of this case is to achieve a higher degree of non-coupling between the two frequency bands and to achieve a similar effect to dual-band switching using liquid crystal. (3) The working principle of the dual-band liquid crystal array reflector in this case is based on the ability to dynamically control the phase of reflected waves from two different frequency bands using liquid crystal technology. This advanced antenna design has significant advantages in terms of flexibility, efficiency, and adaptability, making it an ideal choice for modern communication and radar applications. By utilizing the tunable characteristics of liquid crystals and the control system, the dual-band reflector array can achieve high efficiency and independent operation at multiple frequencies, meeting the growing needs of next-generation wireless systems. (4) Compared with conventional technology, the structure proposed in this case is much simpler than the independent control unit phase, and the circuit design and manufacturing cost are improved and optimized. Although the performance is worse than beam scanning, the fixed dual-band reflection phase makes control and calculation relatively easy, and the appropriate reflection angle can have more application range in the living environment. In addition, the selectivity of the frequency band is also a major feature. Compared with the general dual-band reflective surface, the liquid crystal can adjust the passage of a certain band in real time, rather than reflecting any frequency band at all times. In this environment with extensive coverage of 5G and LOR communication, this selective design can ensure the confidentiality of any frequency band. (5) Compared to individually controlled liquid crystal layer cells, which result in higher cell losses and fail to meet low-loss requirements, this invention is significantly more difficult to design due to the high precision required for controlling bias voltage changes. Furthermore, external factors and errors during actual operation can drastically reduce the success rate, and phase reconstruction is also more challenging. Therefore, compared to individually controlled liquid crystal layer cells, this invention offers advantages such as ease of design, dual-phase reconstruction, ease of implementation, and the ability to achieve the desired frequency band gain and directivity at both receivers.

[0086] The present invention has been disclosed above through the embodiments described above, but it is not intended to limit the present invention. Any person skilled in the art can make some modifications and refinements after understanding the foregoing technical features and embodiments of the present invention, without departing from the spirit and scope of the present invention. Therefore, the scope of patent protection of the present invention shall be determined by the claims attached to this specification.

[0087] 1: First substrate layer 11: First upper surface 111: First surface unit 1111: First surface frame patch 1112: Rectangular patch on the first surface 1113: Rectangular slit on the first surface 1114: First surface cross-shaped patch 12: First lower surface 121: Second surface unit 1211: Tree Patch 12111: First conductive part 12112: Second conductive part 12113: Second conductive part 12114: Second conductive part 2: First liquid crystal layer 3: Second substrate layer 31: Second upper surface 311: Third surface unit 3111: Rectangular patch on the third surface 3112: Third surface metal line 3113: Cross-shaped opening on the third surface 32: Second lower surface 321: Rectangular patch on the fourth surface

Claims

1. An active dual-frequency liquid crystal array reflective structure, comprising: A first substrate layer has a first upper surface and a first lower surface; A second substrate layer having a second upper surface and a second lower surface; A first liquid crystal layer is stacked and connected between a first substrate layer and a second substrate layer; a plurality of first surface units are arranged in an array on the first upper surface, each first surface unit having four first surface frame-shaped patches and one first surface cross-shaped patch, and each first surface frame-shaped patch having a first surface rectangular patch inside; a plurality of second surface units are arranged in an array on the first lower surface, each second surface unit having four tree-shaped patches, any two tree-shaped patches being connected, each tree-shaped patch having a first conductive portion and three second conductive portions, the three second conductive portions being arranged in parallel and connected in series to the first conductive portion; wherein the first conductive portion extends along a first direction, and the second conductive portion extends along a second direction, the first direction and the second direction being different directions; Several third surface units are arranged in an array on the second upper surface, each third surface unit having four third surface rectangular patches, and each third surface rectangular patch having four third surface metal lines connected to its edge; several fourth surface units are arranged in an array on the second lower surface, each fourth surface unit being a fourth surface rectangular patch; wherein the first surface frame patch, the first surface rectangular patch, the first substrate layer, the tree-shaped patch, the first liquid crystal layer, the third surface rectangular patch and the four third surface metal lines connected to the edges of the third surface rectangular patch, and the fourth surface unit form a first reflective unit cell, the first reflective unit cell having a center operating frequency between 27 and 29 GHz when no bias voltage is applied to the first liquid crystal layer; The first surface cross-shaped patch, the first substrate layer, the second surface unit, the first liquid crystal layer, the third surface unit, and the fourth surface unit form a second reflective unit cell. When an electromagnetic wave is incident on the first liquid crystal layer after a bias voltage is applied, the center operating frequency of the second reflective unit cell is between 11 and 13 GHz.

2. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein every four first surface frame-shaped patches are arranged around the first surface cross-shaped patch, and a first surface rectangular slit is provided between the first surface frame-shaped patch and the first surface rectangular patch.

3. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein the lengths of the three second conductive parts are arranged in ascending order and connected in series on the first conductive part, and any two dendritic patches are connected by connecting the second conductive part with the shortest length of any dendritic patch toward the second conductive part with the longest length of the other dendritic patch.

4. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein every four rectangular patches on the third surface are surrounded by a cross-shaped opening on the third surface by the metal lines on the third surface.

5. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein the first surface unit, the second surface unit, the third surface unit and the fourth surface unit are formed of metal.

6. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein the dielectric constant of the first liquid crystal layer is 2.55~3.76 before and after the first liquid crystal layer is biased, and the tangent loss is 0.004~0.

006.

7. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein the length and width of the first surface frame patch are 1~3.8mm, and the length and width of the first surface rectangular patch are 0.4~1.52mm.

8. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein the first surface cross-shaped patch has a first longitudinal portion and a first transverse portion, the length of the first longitudinal portion and the first transverse portion being 2~11mm.

9. The active dual-frequency liquid crystal array reflective structure as described in claim 1, wherein when the first liquid crystal layer is not biased, the first reflective unit cell can be used as a first reflective surface when the center operating frequency is between 27 and 29 GHz; and when the first liquid crystal layer is biased, the second reflective unit cell can be used as a second reflective surface when the center operating frequency is between 11 and 13 GHz.

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