Wideband beam-steerable microstrip patch antenna

Abstract

A broadband beam scanning antenna structure includes a first substrate layer, a second substrate layer, a third substrate layer, a liquid crystal layer, a first surface unit, a second surface unit, a third surface unit, and a fourth surface unit. The liquid crystal layer is stacked between the second substrate layer and the third substrate layer and is in contact with the third surface unit. The beam scanning angle of the broadband beam scanning antenna structure is controlled by applying a liquid crystal bias voltage to the liquid crystal layer to control the angle range of continuous scanning.

Description

Technical Field

[0001] This invention relates to a broadband beam scanning antenna structure, and more particularly to an antenna structure design with beam scanning functionality. Prior Technology

[0002] Traditional microstrip antenna technology is limited by the fact that it can only select a preset frequency and fix the beam direction, thus lacking flexibility in application. Current technological developments typically use technologies such as microelectromechanical systems (MEMS), PIN diodes, variable capacitor diodes, and liquid crystal materials to control the antenna beam in order to achieve one-dimensional beam scanning.

[0003] However, while MEMS or PIN diodes can change the beam direction, it is not continuous. Their technology involves switching the beam direction, so they cannot precisely control the beam direction and can only switch to a pre-designed beam direction. While Varactor diodes can control the beam scanning angle by adjusting the voltage to achieve continuous scanning, their operating frequency has an upper limit.

[0004] Therefore, although microstrip antennas have many advantages, the challenge of balancing wideband operation and performance remains a topic worthy of in-depth research. In particular, when combining liquid crystal materials with array structures for expansion, more challenges need to be faced, such as how to accurately apply voltage to the liquid crystal layer to change the dielectric constant of the liquid crystal to achieve beam reconfiguration.

[0005] This project utilizes the tunable dielectric constant of liquid crystal materials and combines it with the design of microstrip antennas to develop a liquid crystal antenna structure with beam scanning. This antenna design helps to further improve the accuracy and flexibility of using broadband scanning technology and reduce its system construction cost.

[0006] The main feature of this invention is that it integrates the properties of liquid crystal materials into the design of the antenna structure, and controls the direction of the beam by applying a bias voltage to the liquid crystal layer to generate an electric field to modulate the arrangement of liquid crystal molecules, thereby increasing the service area and operational flexibility. Therefore, the technology in this invention is a more powerful solution. Summary of the Invention

[0007] A broadband beam scanning antenna 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 third substrate layer having a third upper surface and a third lower surface; a liquid crystal layer stacked between the second substrate layer and the third substrate layer; a first surface unit formed on the first upper surface, the first surface unit having a large rectangular patch and four small rectangular patches, wherein any two small rectangular patches are located on one side of the large rectangular patch, and the other two small rectangular patches are located on the other side of the large rectangular patch; and a second surface unit formed on the second upper surface, the second surface unit having an elongated patch and two parasitic patch groups, the two parasitic patch groups being respectively disposed on the elongated patch of the second surface. The parasitic patch group comprises two sides of a second surface large rectangular patch, a second surface small rectangular patch, and a second surface strip patch, wherein the two ends of the second surface strip patch are respectively connected to the second surface large rectangular patch and the second surface small rectangular patch; a third surface unit is formed on the third upper surface, the third surface unit has a third surface elongated patch, and the third surface elongated patch has three I-shaped slots, the I-shape of the I-shaped slots extending along a first direction; a fourth surface unit is formed on the third lower surface, the fourth surface unit has a fourth surface strip patch, the fourth surface strip patch also extending along the first direction, and the fourth surface strip patch of the fourth surface unit is a signal feed line; and wherein the beam scanning angle of the broadband beam scanning antenna structure is controlled by applying a liquid crystal bias voltage to the liquid crystal layer to control the range of continuous scanning.

[0008] More specifically, the second surface elongated patch is a main radiating patch, while the two parasitic patch groups are used to increase bandwidth and control beam direction.

[0009] More specifically, the width of the second surface elongated patch is 18.99mm to 19.01mm, and the length of the second surface elongated patch is 8.99mm to 9.01mm.

[0010] More specifically, the width of the large rectangular patch on the second surface is 8.09mm to 8.11mm, and the length of the large rectangular patch on the second surface is 8.09mm to 8.11mm; the width of the small rectangular patch on the second surface is 2.99mm to 3.01mm, and the length of the small rectangular patch on the second surface is 2.99mm to 3.01mm; the width of the strip patch on the second surface is 3.89mm to 3.91mm, and the length of the strip patch on the second surface is 0.99mm to 1.1mm.

[0011] More specifically, the elongated patch on the third surface of the third surface unit is a grounding layer, and the strip-shaped patch on the fourth surface of the fourth surface unit is a microstrip line, while the third surface unit is used as the grounding layer for the fourth surface unit.

[0012] More specifically, the third surface unit is biased with the second surface unit to perform beam scanning.

[0013] More specifically, the first surface unit, the second surface unit, the third surface unit, and the fourth surface unit are formed of a conductive material.

[0014] More specifically, the liquid crystal material of the liquid crystal layer is ZOC-A018XX, in order to control the range of continuous scanning from -42 degrees to 42 degrees, covering a total scanning angle of 84 degrees.

[0015] More specifically, the liquid crystal material of the liquid crystal layer is GT7, in order to control the range of continuous scanning from -42 degrees to 42 degrees, covering a total scanning angle of 84 degrees.

[0016] More specifically, the liquid crystal material of the liquid crystal layer is E7, in order to control the range of continuous scanning from -52 degrees to 52 degrees, covering a total scanning angle of 104 degrees. Simple Explanation of the Diagram

[0017] [Figure 1A] is a multi-layer structure decomposition diagram of the broadband beam scanning antenna structure of the present invention. [Figure 1B] is a schematic diagram of the multi-layer structure combination of the broadband beam scanning antenna structure of the present invention. [Figure 2A] is a schematic diagram of the unit cell design of the first surface element of the broadband beam scanning antenna structure of the present invention. [Figure 2B] is a schematic diagram of the unit cell design of the second surface element of the broadband beam scanning antenna structure of the present invention. [Figure 2C] is a schematic diagram of the unit cell design of the third surface element of the broadband beam scanning antenna structure of the present invention. [Figure 2D] is a schematic diagram of the unit cell design of the fourth surface element of the broadband beam scanning antenna structure of the present invention. [Figure 3A] is a schematic diagram of the reflection loss relative to the signal frequency characteristics of the first embodiment of the broadband beam scanning antenna structure of the present invention. [Figure 3B] is a radiation field diagram of the first embodiment of the broadband beam scanning antenna structure of the present invention. [Figure 4A] is a schematic diagram of the reflection loss relative to the signal frequency characteristics of the second embodiment of the broadband beam scanning antenna structure of the present invention. [Figure 4B] is a radiation field diagram of the second embodiment of the broadband beam scanning antenna structure of the present invention. [Figure 5A] is a schematic diagram of the reflection loss relative to the signal frequency characteristics of the third embodiment of the broadband beam scanning antenna structure of the present invention. [Figure 5B] is a radiation field diagram of the third embodiment of the broadband beam scanning antenna structure of the present invention. Implementation

[0018] 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.

[0019] Please refer to Figures 1A and 1B, which are schematic diagrams of the multilayer structure of a broadband beam scanning antenna. As shown in the figures, the design of this broadband beam scanning antenna structure is mainly a three-layer, four-sided circuit board. The broadband beam scanning antenna structure includes a first substrate layer 1, a second substrate layer 2, a third substrate layer 3, a first surface unit 4, a second surface unit 5, a third surface unit 6, a fourth surface unit 7, and a liquid crystal layer 8.

[0020] The first substrate layer 1 has a first upper surface 11 and a first lower surface 12.

[0021] The second substrate layer 2 has a second upper surface 21 and a second lower surface 22.

[0022] The third substrate layer 3 has a third upper surface 31 and a third lower surface 32.

[0023] The first substrate layer 1, the second substrate layer 2 and the third substrate layer 3 are double-sided circuit boards (e.g., dielectric constant of 3.33±0.08 and dielectric loss of 0.0025), but this invention is not limited to this type of circuit board.

[0024] The first surface unit 4, the second surface unit 5, the third surface unit 6, and the fourth surface unit 7 are formed of conductive materials (such as copper foil, gold foil, or indium tin oxide or other metal oxide conductors).

[0025] The liquid crystal layer 8 is stacked and connected between the second substrate layer 2 and the third surface unit 6.

[0026] The liquid crystal layer 8, when the liquid crystal material is ZOC-A018XX, has the following characteristics: (1) The dielectric constant is 2.55~3.76 and the dielectric loss is 0.004~0.007. (2) In the optimal implementation, when the liquid crystal molecules are horizontal with respect to the electric field direction, the dielectric constant is 3.76 and the dielectric loss is 0.004 (after the liquid crystal layer is biased); while when the liquid crystal molecules are perpendicular with respect to the electric field direction, the dielectric constant is 2.55 and the dielectric loss is 0.007 (before the liquid crystal layer is biased), but this invention is not limited to this type of liquid crystal material.

[0027] The liquid crystal layer 8, when the liquid crystal material is E7, has the following characteristics: (1) The dielectric constant is 2.72~3.17 and the dielectric loss is 0.033~0.05. (2) In the optimal implementation, when the liquid crystal molecules are horizontal with respect to the electric field direction, the dielectric constant is 3.17 and the dielectric loss is 0.033 (after the liquid crystal layer is biased); while when the liquid crystal molecules are perpendicular with respect to the electric field direction, the dielectric constant is 2.72 and the dielectric loss is 0.05 (before the liquid crystal layer is biased), but this invention is not limited to this type of liquid crystal material.

[0028] The liquid crystal layer 8, when the liquid crystal material is GT7, has the following characteristics: (1) The dielectric constant is 2.72~3.17 and the dielectric loss is 0.033~0.05. (2) In the optimal implementation, when the liquid crystal molecules are horizontal with respect to the electric field direction, the dielectric constant is 3.53 and the dielectric loss is 0.0064 (after the liquid crystal layer is biased); while when the liquid crystal molecules are perpendicular with respect to the electric field direction, the dielectric constant is 2.46 and the dielectric loss is 0.0116 (before the liquid crystal layer is biased), but this invention is not limited to this type of liquid crystal material.

[0029] The liquid crystal layer 8 changes its dielectric properties due to the change of electric field, thereby changing the characteristics of the antenna beam. The principle is that when the liquid crystal material is not in contact with the applied voltage, the liquid crystal molecules will align according to the orientation direction. At this time, because the liquid crystal molecules are perpendicular to the direction of the electric field, it is called the vertical state. The liquid crystal at this time has the dielectric constant and dielectric loss of the vertical state.

[0030] When the liquid crystal contact material comes into contact with an applied voltage, and this voltage is greater than the critical voltage, the electric field will drive the liquid crystal molecules to turn so that the liquid crystal molecules are aligned with the direction of the electric field. In other words, the liquid crystal molecules are aligned with the electric field. At this time, the liquid crystal has a dielectric constant and dielectric loss in a parallel state.

[0031] Therefore, in the absence of an electric field, the liquid crystal molecules of the liquid crystal layer 8 are aligned with the y-axis due to the presence of the alignment film; while under a horizontal electric field (the electric field direction is along the y-axis or x-axis), the liquid crystal molecules are aligned with the y-axis due to the presence of the alignment film; and under a vertical electric field (the electric field direction is along the z-axis), the liquid crystal molecules are horizontal to the direction of the electric field.

[0032] As shown in Figure 2A, the first surface unit 4 is formed on the first upper surface 11. The first upper surface 11 is formed by etching a metal layer (e.g., copper foil with a thickness of 35 μm) to form multiple first surface units 4 arranged in an array (only a single one is presented in this case).

[0033] The dimensions of the first upper surface 11 are as follows: W sub1 is 43.5mm~44.5mm, L sub1 is 17.5mm~18.5mm, V 1 is 40mm~40.1mm, and V 2 is 12mm~12.1mm.

[0034] The first surface unit 4 has a first surface large rectangular patch 41 and four first surface small rectangular patches 42, wherein any two first surface small rectangular patches 42 are on the side of the first surface large rectangular patch 41, and the other two first surface small rectangular patches 42 are on one side of the first surface large rectangular patch 41.

[0035] The unit cell design specifications for the first surface unit 4 are as follows: (1) The W stack is 7.49mm~7.51mm, which means it can be considered as 7.5mm in reality. (2) The L stack is 8.49mm~8.51mm, which means it can be considered as 8.5mm in reality. (3) P1 is 0.99mm~1.01mm, which means it can be regarded as 1mm in reality. (4) P2 is 0.99mm~1.01mm, which means it can be regarded as 1mm in reality.

[0036] As shown in Figure 2B, the second surface unit 5 is formed on the second upper surface 21. The second upper surface 21 is formed by etching a metal layer (e.g., copper foil with a thickness of 35 μm) to form multiple second surface units 5 arranged in an array (only a single one is shown in this case).

[0037] The dimensions of the second upper surface 21 are as follows: (1) W sub2 is 49.5mm~50.5mm, which means it can be considered as 50mm in reality. (2) L sub2 is 17.5mm~18.5mm, which means it can be considered as 18mm in reality.

[0038] The second surface unit 5 has a second surface elongated patch 51 and two parasitic patch groups 52 and 53. The two parasitic patch groups 52 and 53 are respectively disposed on both sides of the second surface elongated patch 51. The parasitic patch group 52 has a second surface large rectangular patch 521 and 531, a second surface small rectangular patch 522 and 532 and a second surface strip patch 523 and 533. The two ends of the second surface strip patch 523 and 533 are respectively connected to the second surface large rectangular patch 521 and the second surface small rectangular patch 522 and 532.

[0039] The width (W ph) of the elongated patch 51 on the second surface is 18.99mm~19.01mm, and the length (L ph) of the elongated patch 51 on the second surface is 8.99mm~9.01mm; the width (W ph1) of the large rectangular patches 521 and 531 on the second surface is 8.09mm~8.11mm, and the length (L ph1) of the large rectangular patches 521 and 531 on the second surface is 8.09mm~8.11mm; the width of the small rectangular patches 522 and 532 on the second surface is 2.99mm~3.01mm, and the length of the small rectangular patches 522 and 532 on the second surface is 2.99mm~3.01mm; the width of the strip patches 523 and 533 on the second surface is 3.89~3.91mm, and the length of the strip patches 523 and 533 on the second surface is 0.99mm~1.1mm.

[0040] As shown in the figure, the unit cell design specifications of the second surface unit 5 are as follows: (1) W sub2 is 49.5mm~50.5mm, which means it can be considered as 50mm in reality. (2) L sub2 is 17.5mm~18.5mm, which means it can be considered as 18mm in reality. (3) W ph is 18.99mm~19.01mm, which means it can be regarded as 19mm in reality; where W ph is about 0.475λ. (4) L ph is 8.99mm~9.01mm, which means it can be regarded as 9mm in reality; where L ph is about 0.225λ. (5) W ph1 is 8.09mm~8.11mm, which means it can be regarded as 8.1mm in reality. (6) L ph1 is 8.09mm~8.11mm, which means it can be regarded as 8.1mm in reality. (7) d is 0.49mm~0.51mm, which means it can be regarded as 0.5mm in reality.

[0041] The elongated patch 51 on the second surface is a main radiating patch, while the two parasitic patch groups 52 and 53 are used to increase bandwidth and control beam direction.

[0042] In this case, parasitic patch groups 52 and 53 are used as parasitic patches (parasitic patch group 52 is the first parasitic patch, and parasitic patch group 53 is the second parasitic patch). The parasitic patches are placed on both sides of the main radiating patch, and the parasitic patches and the main radiating patch generate resonance through coupling, thereby forming new resonant frequency points. When these resonant frequency points are properly adjusted and combined, the bandwidth of the antenna is significantly extended.

[0043] As shown in Figures 1A and 2C, the third surface unit 6 is formed on the third upper surface 31. A metal layer (e.g., copper foil with a thickness of 35 μm) is etched on the third upper surface 31 to form multiple third surface units 6 arranged in an array (only one is shown in this case). Since the liquid crystal layer 8 is stacked on the third surface unit 6, it is shown in the figure together.

[0044] The dimensions of the third upper surface 31 are as follows: (1) W sub3 is 49.5mm~50.5mm, which means it can be considered as 50mm in reality. (2) L sub3 is 19.5mm~20.5mm, which means it can be regarded as 20.0mm in reality.

[0045] The dimensions of the liquid crystal layer 8 are as follows: (1) W lc is 40mm~40.1mm, which means it can be regarded as 40.05mm in reality. (2) L lc is 10mm~10.1mm, which means it can be regarded as 10.05mm in reality.

[0046] The third surface unit 6 is a third surface elongated patch with three I-shaped slots 61. The I-shape of the I-shaped slots extends along a first direction, as shown in Figure 1A. The first direction is the Y direction.

[0047] Of the three I-shaped slots 61 on the elongated patch of the third surface, only the central I-shaped slot 61 corresponds to the fourth surface unit 7, while the I-shaped slots 61 on the left and right sides are used to increase bandwidth.

[0048] The unit cell design specifications of the third surface unit 6, wherein the length and width of the elongated patch on the third surface are the same as those of the third upper surface 31, and the dimensions are as follows: (1) W sub3 is 49.5mm~50.5mm, which means it can be considered as 7.5mm in reality. (2) L sub3 is 19.5mm~20.5mm, which means it can be regarded as 8.5mm in reality. (3) h 1 is 1.99mm~2.01mm, which means it can be regarded as 2mm in reality. (4) g 1 is 3.64mm~3.66mm, which means it can be regarded as 3.65mm in reality. (5) h 2 is 3.99mm~4.01mm, which means it can be regarded as 4mm in reality. (6) g 2 is 0.024mm~0.26mm, which means it can be regarded as 0.25mm in reality.

[0049] As shown in Figure 2D, the fourth surface unit 7 is formed on the third lower surface 32. A metal layer (e.g., copper foil with a thickness of 35 μm) is etched on the third lower surface 32 to form multiple fourth surface units 7 arranged in an array (only a single one is shown in this case).

[0050] The dimensions of the third upper surface 31 are as follows: (1) W sub3 is 49.5mm~50.5mm, which means it can be regarded as 50.0mm in reality. (2) L sub3 is 19.5mm~20.5mm, which means it can be regarded as 20.0mm in reality.

[0051] The dimensions of the liquid crystal layer 8 are as follows: (1) W lc is 40mm~40.1mm, which means it can be regarded as 40mm in reality. (2) L lc is 10mm~10.1mm, which means it can be regarded as 10mm in reality.

[0052] The fourth surface unit 7 is a fourth surface strip patch. The unit cell design specifications of the fourth surface unit 7 are as follows: (1) Wp is 0.99mm~1.01mm, which means it can be regarded as 1mm in reality. (2) Lp is 16.09mm~16.11mm, which means it can be regarded as 16.1mm in reality.

[0053] The elongated patch on the third surface of the third surface unit 6 is a grounding layer, while the strip-shaped patch on the fourth surface of the fourth surface unit 7 is a microstrip line. The third surface unit 6 is used as the grounding layer for the fourth surface unit 7.

[0054] The fourth surface unit 7 is biased with the second surface unit 5 to perform beam scanning. The fourth surface strip patch of the fourth surface unit 7 is a signal feed line. That is, the fourth surface strip patch is used as a microstrip line and the signal is fed in using a coupling feed method. In addition, the fourth surface strip patch also extends along the first direction, as shown in Figure 1A. The first direction is the Y direction.

[0055] As shown in Figure 3A, the liquid crystal layer in this case was simulated using three liquid crystal materials (ZOC-A018XX, E7, and GT7). Its characteristics were examined using S-parameter (S11 parameter) diagrams, where the information in the diagram is as follows: (1) The reflection loss (dB) indicated by the coordinates in Figure 3A represents the absolute value of the S11 parameter (in decibels). (2) The unbiased voltage in the figure refers to the S11 parameter when no patch in the antenna is energized; since the liquid crystal molecules can be aligned in a specific direction through the liquid crystal alignment mode, the liquid crystal layer can also have the characteristic of specific alignment when unbiased. (3) The first parasitic patch in the figure refers to the S11 parameter that is changed after the first parasitic patch is powered on; when the first parasitic patch is powered on, a 20V square wave is generated by the signal generator and connected to the parasitic patch group 52 of the second surface unit 5 and the ground plane of the third surface unit 6. (4) The second parasitic patch in the figure refers to the S11 parameter that is changed after the second parasitic patch is powered on; when the second parasitic patch is powered on, a 20V square wave is generated by the signal generator and connected to the parasitic patch group 53 of the second surface unit 5 and the ground plane of the third surface unit 6.

[0056] The liquid crystal layer in this case was simulated using three liquid crystal materials (ZOC-A018XX, E7, and GT7) to examine its characteristics through radiation field diagrams. The information in the diagrams is as follows: (1) The unbiased diagram in the figure refers to the radiation pattern without powering on any patch in the antenna. (2) The first parasitic patch in the figure refers to the radiation field pattern that changes after the first parasitic patch is energized. (3) The second parasitic patch in the figure refers to the radiation field pattern that is changed after the second parasitic patch is energized.

[0057] Different liquid crystal materials (ZOC-A018XX, E7, GT7) have different liquid crystal material properties, which are summarized in Table 1 below. liquid crystal material Perpendicular to the direction of the electric field Dielectric constant (unbiased) The dielectric constant (bias voltage) parallel to the direction of the electric field. Perpendicular to the direction of the electric field Dielectric loss (unbiased) Perpendicular to the direction of the electric field Dielectric loss (bias voltage) Dielectric constant Difference Tunable ability of liquid crystal molecules ( ) ZOC-A018XX 2.72 3.17 0.05 0.45 0.45 14.20% E7 2.46 3.53 0.0116 1.07 1.07 30.31% GT7 2.55 3.76 0.007 1.21 1.21 32.18%

[0058] Table 1. Tunability of liquid crystal molecules ( ) is defined as .

[0059] When the liquid crystal material of the liquid crystal layer is ZOC-A018XX, as shown in Figure 3A, the following simulation data is available, explained below: (1) When there is no bias, its frequency range is 7.08GHz~7.62GHz, the bandwidth is 540MHz, and the bandwidth ratio is 7.2%. (2) When the first parasitic patch is biased, its frequency range is 7.07GHz~7.58GHz, the bandwidth is 510MHz, and the bandwidth ratio is 6.8%. (3) When the second parasitic patch is biased, its frequency range is 7.07GHz~7.58GHz, the bandwidth is 500MHz, and the bandwidth ratio is 6.8%.

[0060] As shown in Figure 3B, the gain is 6.94 dBi when unbiased at 0°; the gain is 6.53 dBi when the first parasitic patch is biased at 42°; and the gain is 6.57 dBi when the second parasitic patch is biased at -42°.

[0061] When the liquid crystal material of the liquid crystal layer is E7, as shown in Figure 4A, the following simulation data are available, explained below: (1) When there is no bias, its frequency range is 7.04GHz~7.61GHz, the bandwidth is 570MHz, and the bandwidth ratio is 7.6%. (2) When the first parasitic patch is biased, its frequency range is 7.03GHz~7.58GHz, the bandwidth is 550MHz, and the bandwidth ratio is 7.3%. (3) When the second parasitic patch is biased, its frequency range is 7.04GHz~7.58GHz, the bandwidth is 540MHz, and the bandwidth ratio is 7.2%.

[0062] As shown in Figure 4B, the gain is 3.96 dBi when unbiased at 0°; the gain is 4.26 dBi when the first parasitic patch is biased at 52°; and the gain is 4.26 dBi when the second parasitic patch is biased at -52°.

[0063] When the liquid crystal material of the liquid crystal layer is GT7, as shown in Figure 5A, the following simulation data is available, explained below: (1) When there is no bias, its frequency range is 7.11GHz~7.66GHz, the bandwidth is 550MHz, and the bandwidth ratio is 7.3%. (2) When the first parasitic patch is biased, its frequency range is 7.09GHz~7.61GHz, the bandwidth is 520MHz, and the bandwidth ratio is 6.9%. (3) When the second parasitic patch is biased, its frequency range is 7.08GHz~7.60GHz, the bandwidth is 520MHz, and the bandwidth ratio is 6.9%.

[0064] As shown in Figure 5B, the gain is 7.02 dBi when unbiased at 0°; the gain is 6.23 dBi when the first parasitic patch is biased at 42°; and the gain is 6.25 dBi when the second parasitic patch is biased at -42°.

[0065] Table 2 below shows the characteristics of antennas using different liquid crystal materials. The data is as follows: Table 2. Antenna Characteristics of Different Liquid Crystal Materials liquid crystal material Center frequency (GHz) Dimensions (mm) (Length * Width) bandwidth(%) Scanning angle Gain (θ=0°) ZOC-A018XX 7.5 50*20 7.2 -42° to 42° 6.94dBi E7 7.5 50*20 7.6 -52° to 52° 3.96dBi GT7 7.5 50*20 7.3 -42° to 42° 7.20dBi

[0066] The bandwidth size / center frequency shown in Table 2 refers to the bandwidth with the S11 parameter below -10dB as the reference line, and the center frequency is 7.5GHz.

[0067] The broadband beam scanning antenna structure provided by this invention has the following advantages compared with other conventional technologies: (1) This case is a design of a broadband liquid crystal antenna structure based on the combination of liquid crystal material and microstrip antenna. This design has the function of controlling beam scanning by applying liquid crystal bias voltage. This case utilizes the tunable dielectric constant characteristics of liquid crystal material and combines it with the design of microstrip antenna to develop a liquid crystal antenna structure with beam scanning. (2) The design of this case uses liquid crystal material as the control technology for antenna beam scanning, and through the use of parasitic patches and their graphic and structural design, it achieves the excellent effect of improving accuracy and flexibility and reducing the system construction cost. (3) The main feature of this case is that the characteristics of liquid crystal material are integrated into the design of antenna structure, and the direction of beam is controlled by generating an electric field by applying a bias voltage to the liquid crystal layer to modulate the arrangement of liquid crystal molecules, thereby increasing the service area of ​​the positioning system and its operational flexibility. This will provide a stronger and more powerful solution for the optimization design and performance improvement of the positioning system. (4) The liquid crystal material used in this case is ZOC-A018XX or GT7. The beam scanning angle can be continuously scanned from -42° to 42° by applying liquid crystal bias voltage, covering a total scanning angle of 84°. (5) The liquid crystal material used in this case is E7, and the beam scanning angle can be continuously scanned from -52° to 52° by applying liquid crystal bias voltage, covering a total scanning angle of 104°. (6) Compared with similar liquid crystal antenna literature, the scanning angle shown in general literature is usually only about 40°. Therefore, this invention has significantly better performance in beam scanning capability.

[0068] 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.

[0069] 1: First substrate layer 11: First upper surface 12: First lower surface 2: Second substrate layer 21: Second upper surface 22: Second lower surface 3: Third substrate layer 31: Third upper surface 32: Third lower surface 4: First surface unit 41: Large rectangular patch on the first surface 42: Small rectangular patch on the first surface 5: Second surface unit 51: Second surface elongated patch 52: Parasitic patch group 521: Large rectangular patch on the second surface 522: Small rectangular patch on the second surface 523: Second surface strip patch 53: Parasitic patch group 531: Large rectangular patch on the second surface 532: Small rectangular patch on the second surface 533: Second surface strip patch 6: Third surface unit 61: I-shaped slot 7: Fourth surface unit 8: Liquid Crystal Layer

Claims

1. A broadband beam scanning antenna 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 third substrate layer having a third upper surface and a third lower surface; a liquid crystal layer stacked between the second substrate layer and the third substrate layer; a first surface unit formed on the first upper surface, the first surface unit having a first surface large rectangular patch and four first surface small rectangular patches, wherein any two first surface small rectangular patches are located on one side of the first surface large rectangular patch, and the other two first surface small rectangular patches are located on one side of the first surface large rectangular patch; A second surface unit is formed on the second upper surface. The second surface unit has a second surface elongated patch and two parasitic patch groups. The two parasitic patch groups are respectively disposed on both sides of the second surface elongated patch. Each parasitic patch group has a second surface large rectangular patch, a second surface small rectangular patch, and a second surface strip patch. The two ends of the second surface strip patch are respectively connected to the second surface large rectangular patch and the second surface small rectangular patch. A third surface unit is formed on the third upper surface. The third surface unit has a third surface elongated patch with three I-shaped slots. The I-shape of the I-shaped slots extends along a first direction. A fourth surface unit is formed on the third lower surface. The fourth surface unit has a fourth surface strip patch that extends along the first direction and serves as a signal feed line. The beam scanning angle of the broadband beam scanning antenna structure is controlled by applying a liquid crystal bias voltage to the liquid crystal layer to control the angle range of continuous scanning.

2. The broadband beam scanning antenna structure as described in claim 1, wherein the elongated patch on the second surface is a main radiating patch, and the two parasitic patch groups are used to enhance bandwidth and control beam direction.

3. The broadband beam scanning antenna structure as described in claim 1, wherein the width of the elongated patch on the second surface is 18.99 mm to 19.01 mm and the length of the elongated patch on the second surface is 8.99 mm to 9.01 mm.

4. The broadband beam scanning antenna structure as described in claim 1, wherein the width of the large rectangular patch on the second surface is 8.09 mm to 8.11 mm, and the length of the large rectangular patch on the second surface is 8.09 mm to 8.11 mm; the width of the small rectangular patch on the second surface is 2.99 mm to 3.01 mm, and the length of the small rectangular patch on the second surface is 2.99 mm to 3.01 mm; the width of the strip patch on the second surface is 3.89 mm to 3.91 mm, and the length of the strip patch on the second surface is 0.99 mm to 1.1 mm.

5. The broadband beam scanning antenna structure as described in claim 1, wherein the elongated patch on the third surface of the third surface unit is a ground layer, and the strip patch on the fourth surface of the fourth surface unit is a microstrip line, and the third surface unit is used as the ground for the fourth surface unit.

6. The broadband beam scanning antenna structure as described in claim 4, wherein the third surface element is biased with the second surface element to perform beam scanning.

7. The broadband beam scanning antenna structure as described in claim 1, wherein the first surface element, the second surface element, the third surface element and the fourth surface element are formed of a conductive material.

8. The broadband beam scanning antenna structure as described in claim 1, wherein by applying a liquid crystal bias control to the liquid crystal layer, it is possible to control the range of continuous scanning from -42 degrees to 42 degrees, wherein the scanning angle covers a total of 84 degrees.

9. The broadband beam scanning antenna structure as described in claim 8, wherein the liquid crystal material of the liquid crystal layer is ZOC-A018XX or GT7.

10. The broadband beam scanning antenna structure as described in claim 1, wherein by applying a liquid crystal bias control to the liquid crystal layer, it is possible to control the range of continuous scanning from -52 degrees to 52 degrees, wherein the scanning angle covers a total of 104 degrees.

11. The broadband beam scanning antenna structure as described in claim 10, wherein the liquid crystal material of the liquid crystal layer is E7.

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