Liquid crystal microwave phased array antenna with broadband dielectric resonance

Abstract

The invention discloses a broadband dielectric resonant liquid crystal microwave phased array antenna, which belongs to the technical field of microwave phased array antennae, and comprises antenna units, each antenna unit comprises a radiation unit, a first glass substrate layer, a grounding copper layer, a liquid crystal layer, an inverted spiral microstrip phase shift layer and a second glass substrate layer, the radiation unit is located on the upper surface of the first glass substrate layer, the grounding copper layer is located on the lower surface of the first glass substrate layer, and a coupling gap is formed in the grounding copper layer; the inverted spiral micro-strip phase shift layer corresponds to the opening position so as to allow electromagnetic waves to be coupled to the radiation unit, and the inverted spiral micro-strip phase shift layer is immersed in the liquid crystal layer. According to the invention, the problem that most of the existing devices can only work in a one-dimensional plane and cannot realize broadband wide-angle scanning is solved. The phase of the antenna can be accurately regulated and controlled, the radiation performance of the antenna is improved, the flexibility and adaptability of the antenna are greatly improved while high performance is kept, and the integration level and portability of the antenna are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave phased array antennas, and in particular to a liquid crystal microwave phased array antenna with broadband dielectric resonance. Background Art

[0002] In recent years, the advancement of communications technology has placed higher demands on antenna design, and new phased array antenna design methods and concepts have become a major research hotspot. Traditional mechanical rotating phased arrays suffer from large size, poor reliability, and heavy weight, problems that can be addressed through new reconfigurable technologies.

[0003] Existing reconfigurable phased array beam scanning loading methods are primarily divided into two categories: electrical tuning and functional materials. Electrical tuning includes MEMS switches and PIN diodes, while functional materials include ferrites and liquid crystals. However, PIN diodes, which are electrically tuned devices, introduce high insertion loss at higher frequency RF signals, significantly reducing antenna radiation efficiency. Their nonlinear characteristics also easily cause distortion in broadband and high-power operation. MEMS switches require high drive voltages, typically 10-100V, and are highly sensitive to ambient operating temperature. Liquid crystals, as tunable materials, offer low loss, low drive voltage, high continuous adjustability, and strong frequency selectivity, making them another viable solution for reconfigurable technology. Therefore, liquid crystal phased array antennas hold significant research value in modern wireless communications.

[0004] With existing technologies, most liquid crystal microwave phased array antennas can only operate in a one-dimensional plane and cannot achieve broadband and wide-angle scanning. Summary of the Invention

[0005] The purpose of the present invention is to provide a liquid crystal microwave phased array antenna with broadband dielectric resonance, which uses liquid crystal as an electrically tunable medium to achieve the functions of two-dimensional scanning and reconfigurable directional pattern, and can realize broadband and wide-angle scanning, thereby solving the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A broadband dielectric resonance liquid crystal microwave phased array antenna, comprising:

[0008] Antenna units, each antenna unit comprising a radiating element, a first glass substrate layer, a grounding copper layer, a liquid crystal layer, an inverted spiral microstrip phase shift layer, and a second glass substrate layer, wherein the radiating element is located on the upper surface of the first glass substrate layer, the grounding copper layer is located on the lower surface of the first glass substrate layer, and a coupling slot is provided on the grounding copper layer;

[0009] The inverted spiral microstrip phase shift layer is located on the upper surface of the second glass substrate layer. The corresponding opening positions on the inverted spiral microstrip phase shift layer allow electromagnetic waves to couple to the radiation unit. The liquid crystal layer is composed of a high-strength epoxy resin encapsulated between the inverted spiral microstrip phase shift layer and the grounding copper layer, and the inverted spiral microstrip phase shift layer is immersed in the liquid crystal layer.

[0010] Preferably, the radiating units are arranged horizontally and vertically at equal intervals to form an array antenna. The array antenna has an axisymmetric structure in the vertical direction and a sequential structure in the horizontal direction. Each antenna unit is formed by a cascade of power dividers, and the high-frequency signal source is fed into the k connector at the head end of the power divider. The phase of each antenna unit is independently controlled by a separately led low-frequency AC bias line, wherein the inverted spiral microstrip phase shift layer and the grounded copper layer of the antenna unit are energized by a bias circuit loaded on the upper surface of the second glass substrate layer, wherein the grounded copper layer serves as the negative electrode, and the bias voltage control circuit is implemented on the periphery of the inverted spiral microstrip phase shift layer, and does not interfere with the radio frequency circuit, and the antenna structure is connected by an FPC soft strip line, and the power supply is connected to realize voltage supply.

[0011] Preferably, the radiation unit is a cube of high dielectric ceramic material and has two rectangular radiators of the same material on the upper side. Dielectric resonance generates higher-order modes outside the fundamental mode to broaden the antenna bandwidth, and mode merging realizes a large-bandwidth antenna.

[0012] Preferably, the radiation unit has radiation characteristics different from those of the metal copper layer, and reduces antenna surface wave coupling in the array to achieve large-angle scanning, so that the entire radiation unit can achieve broadband linear polarization radiation.

[0013] Preferably, the microstrip line of the inverted spiral microstrip phase shift layer is a metal copper microstrip line with a characteristic impedance of 50 ohms, which is used for impedance matching with a standard 50 ohm coaxial cable connector and is also matched with a 50 ohm impedance power divider in the array.

[0014] Preferably, the head end of the inverted spiral microstrip phase shift layer is connected to a high-frequency coupling structure for passing high-frequency signals and blocking low-frequency voltages from entering the signal source. At the same time, there is a low-pass filtering structure on the array bias circuit for passing low-frequency signals and blocking high-frequency signals from entering the power supply.

[0015] Preferably, the inverted spiral microstrip phase shift layer and the bias circuit are both present on the upper surface of the second glass substrate layer, and the spiral microstrip multiplexing high-frequency signal circuit is also fed as the positive voltage pole, and due to the presence of the high-frequency coupling structure and the low-pass filtering structure, the two frequencies do not affect each other.

[0016] Preferably, the coupling gap is a rectangular slit structure of the grounded copper layer, and the high-frequency signal at the tail end of the spiral line in the inverted spiral microstrip phase shift layer is coupled to the radiation unit through the coupling gap and radiated out, and the coupling gap is surrounded by a metal ground copper layer, which is used as a negative bias electrode.

[0017] Preferably, the inverted spiral microstrip phase shift layer and the ground copper layer are bonded together by glue, the bonding layer is a high-strength epoxy resin layer, and the liquid crystal layer is encapsulated therein.

[0018] Preferably, the liquid crystal layer includes a polyimide film layer, which is coated on the surface of the inverted spiral microstrip phase shift layer and the grounded copper layer, serving as an anchoring layer for the liquid crystal layer material to determine the orientation of the liquid crystal molecules and stabilize the initial arrangement of the liquid crystal molecules; polymer microspheres with a uniform diameter of 50 microns are present in the liquid crystal layer to control the thickness of the liquid crystal layer; when the liquid crystal layer is treated with the polyimide film anchoring layer, if no bias voltage is applied, the liquid crystal molecules are oriented in the same direction, and the liquid crystal material has the smallest dielectric constant at this time; when a bias voltage is applied to the inverted spiral microstrip phase shift layer and the grounded copper layer, the liquid crystal molecules are deflected, the dielectric constant of the liquid crystal material changes, and the phase of the corresponding inverted spiral microstrip phase shift layer changes, thereby achieving phase change of the antenna unit.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The liquid crystal layer of the present invention adjusts the phase shift of the inverted spiral microstrip phase shifter. By independently controlling the voltages on the upper and lower surfaces of the liquid crystal layer, precise control of the antenna phase can be achieved, thus meeting the requirements of multi-angle operation. The layered placement of the radiating structure and the liquid crystal phase shifter effectively addresses the performance issues associated with the electric field coupling effect of the inverted microstrip network. The lower surface of the first glass substrate layer is completely copper-plated, and a coupling gap is provided. This allows for efficient coupling between the radiating structure and the liquid crystal phase shifter structure, improving the antenna's radiation performance. Leveraging the reusability of the inverted spiral microstrip phase shifter, low-frequency power supply voltage and high-frequency signal sources are introduced into the structure. A bias circuit applies voltage to the antenna to change the dielectric constant of the liquid crystal, enabling beam control. The single-layer liquid crystal structure and compact design significantly enhance the antenna's flexibility and adaptability while maintaining high performance. This effectively reduces the volume and weight of the antenna array, further improving the antenna's integration and portability. The liquid crystal structure and dielectric resonant radiating structure address the inability of existing liquid crystal microwave phased array antennas to achieve wideband angular scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the broadband dielectric resonance liquid crystal microwave phased array antenna of the present invention;

[0022] Figure 2 A bottom view of the array structure of the broadband dielectric resonance liquid crystal microwave phased array antenna of the present invention;

[0023] Figure 3 A top view of the array structure of the broadband dielectric resonance liquid crystal microwave phased array antenna of the present invention;

[0024] Figure 4 is a top view of the inverted spiral microstrip phase shifter of the present invention;

[0025] Figure 5 This is a diagram showing the structure of the liquid crystal layer of the broadband dielectric resonance liquid crystal microwave phased array antenna of the present invention.

[0026] In the figure: 1. Radiating unit; 2. First glass substrate layer; 3. Grounding copper layer; 4. Liquid crystal layer; 5. Inverted spiral microstrip phase shift layer; 6. Second glass substrate layer; 11. Low-pass filter structure; 12. High-frequency coupling structure; 13. Coupling gap; 14. Polymer microspheres; 15. Polyimide film layer. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In order to solve the problem that most of the existing liquid crystal microwave phased array antennas can only work in one-dimensional plane and cannot achieve broadband wide-angle scanning, please refer to Figure 1-Figure 5 , this embodiment provides the following technical solutions:

[0029] A broadband dielectric resonance liquid crystal microwave phased array antenna, comprising:

[0030] Antenna units, each antenna unit includes a radiating element 1, a first glass substrate layer 2, a grounding copper layer 3, a liquid crystal layer 4, an inverted spiral microstrip phase shift layer 5 and a second glass substrate layer 6, wherein the radiating element 1 is located on the upper surface of the first glass substrate layer 2, the grounding copper layer 3 is located on the lower surface of the first glass substrate layer 2, and a coupling slot 13 is provided on the grounding copper layer 3. The radiating element 1 and the grounding copper layer 3 are connected through the coupling slot 13, and the inverted spiral microstrip phase shift layer 5 and the grounding copper layer 3 are energized through a bias line.

[0031] The inverted spiral microstrip phase shift layer 5 is located on the upper surface of the second glass substrate layer 6. The corresponding opening positions on the inverted spiral microstrip phase shift layer 5 allow electromagnetic waves to couple to the radiation unit 1. The liquid crystal layer 4 is composed of a high-strength epoxy resin encapsulated between the inverted spiral microstrip phase shift layer 5 and the ground copper layer 3, and the inverted spiral microstrip phase shift layer 5 is immersed in the liquid crystal layer 4.

[0032] In this embodiment, the radiation units 1 are arranged horizontally and vertically at equal intervals to form an array antenna. The array antenna has an axisymmetric structure in the vertical direction and a sequential structure in the horizontal direction. Each antenna unit is formed by a cascade of power dividers, and the high-frequency signal source is fed into the k connector at the head end of the power divider. The phase of each antenna unit is independently controlled by a separately derived low-frequency AC bias line. The inverted spiral microstrip phase shift layer 5 and the grounded copper layer 3 of the antenna unit are energized by a bias circuit loaded on the upper surface of the second glass substrate layer 6, wherein the grounded copper layer 3 serves as the negative electrode. The bias voltage control circuit is implemented on the periphery of the inverted spiral microstrip phase shift layer 5, does not interfere with the radio frequency circuit, and is connected to the antenna structure by an FPC soft strip line and connected to a power supply to provide voltage.

[0033] Specifically, the first glass substrate layer 2 serves as the upper support structure for the antenna unit. A high-dielectric-constant radiating element 1 is attached to its upper surface, responsible for transmitting and receiving electromagnetic waves. A liquid crystal layer 4 fills the space between the grounded copper layer 3 and the inverted spiral microstrip phase shifter layer 5. High-strength epoxy resin sealing ensures the stability and reliability of the liquid crystal material. A coupling gap 13 is designed on the grounded copper layer 3, which not only allows for effective coupling of electromagnetic waves but also ensures the electrical continuity of the structure. The second glass substrate layer 6 serves as the bottom support structure for the antenna unit. The inverted spiral microstrip phase shifter 5 on its upper surface corresponds to the opening position to allow electromagnetic waves to couple to the radiating element 1. Furthermore, the inverted spiral microstrip phase shifter 5 is placed on the upper surface of the second glass substrate layer 6 and immersed in the liquid crystal layer 4. Through its compact spiral structure, the dielectric constant of the liquid crystal can be changed when powered, thereby achieving precise phase adjustment. This design enables each antenna unit to independently control its radiation phase, providing great flexibility for beamforming and scanning.

[0034] It's important to note that liquid crystal, as a tunable dielectric material, is widely used in phase shifters and phased array antennas due to its low cost, low power consumption, low high-frequency loss, and ease of integration. While numerous liquid crystal-based phase shifters, filters, metasurfaces, and reflectarray antennas have been developed, the design of liquid crystal phased arrays remains relatively limited. Liquid crystal microwave phased array antennas combine the electrically adjustable properties of liquid crystal materials with the beam steering capabilities of phased array antennas to flexibly adjust the antenna's radiation direction and frequency across different operating frequency bands, significantly enhancing the flexibility and adaptability of antenna systems. This technology can effectively reduce the size and weight of antenna arrays, further improving the antenna's integration and portability. Among them, liquid crystal is a new type of tunable element, and its operating frequency band can be used in the microwave field. The LC molecule is an anisotropic material, and its molecular orientation can be controlled by an external electric field or the surface of the orientation layer. When an external electric field acts on the liquid crystal material, the electric field will induce the LC molecules to deflect from the main axis direction along the direction of the electric field. The loss tangent will decrease with the deflection of the molecules, and the dielectric constant will increase. Therefore, the continuous adjustability of LC depends on the applied voltage, and the voltage size affects the characteristics of the LC molecules. By replacing the dielectric materials in existing microwave topologies, such as planar topologies and waveguide structures, with LC, a tunable microwave topology can be obtained. By using the concept of an adjustable delay line, the electrical length is changed by changing the dielectric constant of LC to obtain a phase difference and realize antenna scanning.

[0035] Therefore, by utilizing the characteristic that the dielectric properties of liquid crystal materials change with voltage, the antenna scanning angle can be flexibly adjusted, greatly broadening the flexibility of antenna use. Secondly, the design of the inverted spiral microstrip phase shift layer 5 utilizes the reusability of the inverted spiral microstrip phase shift to introduce low-frequency power supply voltage and high-frequency signal source into the structure. The bias circuit loads voltage on the antenna to achieve a change in the dielectric constant of the liquid crystal and realize beam control. Finally, the symmetrical structure of the array antenna and the design of independently controlled bias lines simplify the complexity of the control system and improve the overall performance and stability of the antenna.

[0036] In this embodiment, the radiating unit 1 is a cube of high-dielectric ceramic material and has two rectangular radiators of the same material on the upper side. The dielectric resonance generates higher-order modes outside the fundamental mode to broaden the antenna bandwidth, and mode merging realizes a large-bandwidth antenna. The radiating unit 1 has different radiation characteristics from the metal copper layer. The antenna surface wave coupling is reduced in the array to achieve large-angle scanning, so that the overall radiating unit 1 can achieve broadband linear polarization radiation, thereby enhancing the radiation angle and directivity of the antenna.

[0037] Specifically, the radiation unit 1 is designed to be a cube of high dielectric ceramic material and has two rectangular radiators of the same material on the upper side. The dielectric resonance can generate higher-order modes outside the fundamental mode to broaden the antenna bandwidth, and mode merging can realize a large-bandwidth antenna. To a certain extent, it not only optimizes the distribution path of the electric field mode, but also reduces unnecessary reflections and interference. Through the above design to match the operating frequency of the antenna and the required radiation characteristics, the overall radiation unit 1 can achieve broadband linear polarization radiation, which is different from the radiation characteristics of the metal copper layer. In the array, the antenna surface wave coupling can be reduced to achieve large-angle scanning, thereby increasing the scanning angle of the antenna and reducing the cross-polarization level, thereby enhancing the antenna's anti-interference ability and signal reception quality, and improving the overall working effect of the antenna.

[0038] By adopting the above technical solution, the radiation performance of the dielectric resonant liquid crystal microwave phased array antenna has been improved. The design of high dielectric constant radiation material not only increases the bandwidth of the antenna, but also improves the scanning angle and directivity of the antenna, allowing the antenna to work better in different electromagnetic environments.

[0039] In this embodiment, the microstrip line of the inverted spiral microstrip phase shift layer 5 is a metal copper microstrip line with a characteristic impedance of 50 ohms, which is used to perform impedance matching with a standard 50 ohm coaxial cable connector and to perform matching with a 50 ohm impedance power divider in the array.

[0040] Specifically, the microstrip line of the inverted spiral microstrip phase-shift layer 5 is a metal copper microstrip line with a characteristic impedance of 50 ohms. It is used for impedance matching with a standard 50-ohm coaxial connector, enabling it to match the impedance of the 50-ohm coaxial structure and minimize signal loss and reflection during transmission, thereby ensuring signal integrity and transmission efficiency. It also serves as a power divider in the array to match the 50-ohm impedance. In actual material selection, based on actual needs, the microstrip line material can be selected from a high-conductivity metal, such as gold or tinned copper, to further reduce transmission loss and improve electrical performance. In addition, the inverted spiral design enables a compact structural layout, achieving the desired phase shift effect within a limited space, and meeting the design requirements of high-performance microwave circuits.

[0041] In this embodiment, the head end of the inverted spiral microstrip phase shift layer 5 is connected to a high-frequency coupling structure 12, which is used to pass high-frequency signals and block low-frequency voltages from entering the signal source, thereby preventing low-frequency voltages from entering the signal source and causing an impact. At the same time, there is a low-pass filtering structure 11 on the array bias circuit, which is used to pass low-frequency signals and block high-frequency signals from entering the power supply.

[0042] Specifically, the head end of the inverted spiral microstrip phase shift layer 5 is connected to a high-frequency coupling structure 12, which is used to pass high-frequency signals and block low-frequency voltages from entering the signal source; at the same time, there is a low-pass filtering structure 11 on the array bias circuit, which is used to pass low-frequency signals and block high-frequency signals from entering the power supply. The inverted spiral microstrip phase shift layer 5's design of multiplexing electrical signals of different frequencies can prevent high-frequency signals from damaging the power supply, while meeting the conditions for applying low-frequency voltages to the liquid crystal.

[0043] In this embodiment, the inverted spiral microstrip phase shift layer 5 and the bias circuit are both present on the upper surface of the second glass substrate layer 6. The spiral microstrip multiplexing high-frequency signal circuit also serves as the positive voltage electrode for power feeding. Due to the presence of the high-frequency coupling structure 12 and the low-pass filtering structure 11, the two frequencies do not affect each other.

[0044] In this embodiment, the coupling slot 13 is a rectangular slot structure of the ground copper layer 3. Through the slot, the high-frequency signal at the tail end of the spiral line in the inverted spiral microstrip phase shift layer 5 is coupled to the radiation unit 1 through the coupling slot 13 and radiated out. In addition, the coupling slot 13 is surrounded by a metal ground copper layer, which is used as a negative bias electrode.

[0045] Specifically, the coupling slot 13 adopts a rectangular design. The linear coupling slot 13 on the ground copper layer 3 can provide a more direct and effective electromagnetic coupling path, making the signal transmission between the radiating structure and the liquid crystal phase shifter structure smoother, and reducing the signal distortion and loss caused by the irregular slot shape. Specifically, the ground copper layer 3 is hollowed out to form the coupling slot 13, and the coupling slot 13 is plated with a copper layer on all sides. The coupling slot 13 is opened in a rectangular shape on the ground copper layer 3. Through the opening, the high-frequency signal at the tail end of the spiral line in the inverted spiral microstrip phase shift layer 5 is coupled to the radiating unit 1 through the coupling slot 13 and radiated out. The above design ensures smooth signal transmission, and the coupling slot 13 is completely surrounded by a metal ground copper layer, which also serves as the negative bias lead.

[0046] By adopting the above technical solution, the accuracy and consistency of the coupling gap 13 are ensured, the signal transmission loss caused by processing errors is reduced, and the copper plating improves the conductivity of the gap, so that the signal can maintain higher efficiency and stability during the transmission process, thereby enhancing the reliability of the antenna.

[0047] In this embodiment, the inverted spiral microstrip phase shift layer 5 and the ground copper layer 3 are bonded together by glue, the bonding layer is a high-strength epoxy resin layer, and the liquid crystal layer 4 is encapsulated therein.

[0048] Specifically, a ring of epoxy resin surrounds the liquid crystal layer 4, encapsulating the liquid crystal. A high-strength epoxy resin layer serves as an adhesive layer, connecting the lower surface of the first glass substrate layer 2 to the upper surface of the second glass substrate layer 6. This high-strength epoxy resin layer ensures a secure bond between the two layers, while its sealing properties effectively seal the liquid crystal layer 4 within the gap, forming a liquid crystal layer. This ring of high-strength epoxy resin prevents leakage and contamination of the liquid crystal, ensuring the long-term stability and reliability of the liquid crystal phased array antenna.

[0049] In this embodiment, the dielectric constant of the first glass substrate layer 2 and the second glass substrate layer 6 is 4.6, and the relative dielectric constant of the liquid crystal layer 4 is adjustable in the range of 2.5-3.65. By using the first glass substrate layer 2 and the second glass substrate layer 6 with a dielectric constant of 4.6 as the base material, a stable support structure with good electrical performance can be achieved.

[0050] Specifically, the liquid crystal layer 4 used is designed to have an adjustable range of relative dielectric constant between 2.5 and 3.65. The above design ensures that the response of the liquid crystal material under the action of the electric field is sensitive and controllable. The high dielectric constants of the first glass substrate layer 2 and the second glass substrate layer 6 provide stable electrical isolation and support, enabling the liquid crystal device to operate stably in complex electromagnetic environments. At the same time, its electrical performance can be quickly adjusted according to actual needs, meeting the requirements of modern communication technology for high-performance, tunable devices.

[0051] In this embodiment, the liquid crystal layer 4 includes a polyimide film layer 15, which is coated on the surface of the inverted spiral microstrip phase shift layer 5 and the grounding copper layer 3, serving as an anchor layer for the liquid crystal layer material to determine the orientation of the liquid crystal molecules and stabilize the initial arrangement of the liquid crystal molecules.

[0052] Specifically, the polyimide film layer 15 is coated on the surfaces of the inverted spiral microstrip phase-shift layer 5 and the grounding copper layer 3. Its chemical and physical properties effectively interact with the liquid crystal molecules, ensuring that the liquid crystal molecules maintain a stable alignment in their initial state. The polyimide film layer 15 acts as an anchoring layer for the liquid crystal layer, effectively fixing the initial alignment of the liquid crystal molecules and reducing disturbances in the liquid crystal alignment caused by environmental changes such as temperature and pressure, thereby ensuring consistent antenna operation under varying conditions. Furthermore, the polyimide film layer 15 also exhibits excellent insulation and chemical stability, protecting the antenna structure from potential damage such as corrosion and short circuits, thereby extending the antenna's service life.

[0053] The liquid crystal layer 4 contains polymer microspheres 14 with a uniform diameter of 50 micrometers, which are used to control the thickness of the liquid crystal layer 4 .

[0054] Specifically, polymer microspheres 14 with a uniform diameter of 50 μm are uniformly dispersed in the liquid crystal layer 4. As fillers in the liquid crystal layer 4, the polymer microspheres 14 can stabilize the physical properties of the liquid crystal. Due to their uniform distribution and consistent diameter, they provide a stable support structure and a uniform dielectric environment for the liquid crystal layer 4.

[0055] After the liquid crystal layer 4 is treated with the polyimide film layer 15 anchor layer, if no bias voltage is applied, the liquid crystal molecules are oriented in the same direction. At this time, the liquid crystal material has a minimum dielectric constant. When a bias voltage is applied to the inverted spiral microstrip phase shift layer 5 and the ground copper layer 3, the liquid crystal molecules are deflected, the dielectric constant of the liquid crystal material changes, and the phase of the corresponding inverted spiral microstrip phase shift layer 5 changes, thereby achieving a phase change of the antenna unit.

[0056] Specifically, when an external electric field acts on the inverted spiral microstrip phase-shift layer 5 and the grounded copper layer 3, the electric field induces the LC molecules to deflect from their principal axis along the direction of the electric field. The liquid crystal molecules shift from being parallel to the ground plane to being perpendicular to the ground plane. The loss tangent decreases with molecular deflection, while the dielectric constant increases. The continuous adjustability of the liquid crystal depends on the applied voltage, which affects the molecular properties of the liquid crystal. Utilizing the concept of an adjustable delay line, the spiral microstrip achieves a change in electrical length in response to a change in the liquid crystal dielectric constant. Simultaneously, this change in the liquid crystal dielectric constant produces a 360-degree phase shift in the spiral.

[0057] Specifically, in order to independently control the phase variable of each antenna unit, a 15um high-resistance bias line is guided to each independent spiral delay line. The positive bias line, the power divider, and the inverted spiral microstrip phase shift layer 5 are on the same layer, and the negative electrode and the ground copper layer 3 are on the same surface. The introduction of the bias line facilitates the application of voltage to the liquid crystal.

[0058] During actual use or operation, the liquid crystal molecules calibrated by the polyimide film layer 15 are in a stable initial state. By simply adjusting the independent bias voltage on each antenna unit, the phase of the electrical signal of a single antenna unit can be precisely controlled, thereby enhancing the flexibility and practicality of the phase shifter.

[0059] Among them, realizing the angle scanning of the array antenna requires applying different voltages to the units according to the principle of phased array beamforming to form equidistant phase differences, so as to achieve the purpose of controlling the beam deflection angle.

[0060] Specifically, the array deflection requires a progressive phase difference in each row or column of the array to deflect the beam away from the main axis. The phase difference in each row or column corresponds to the different dielectric constants of the liquid crystals and is determined by the configured bias voltage. By applying a simple low-frequency voltage to the liquid crystal layer 4 and applying different voltages to different cells, in order to achieve h-plane beam deflection, each row of liquid crystal perpendicular to the h-plane must have the same bias voltage to produce the same phase, while each column of liquid crystal parallel to the h-plane must have a different bias voltage to produce a progressive phase difference. The same applies to the e-plane, achieving two-dimensional scanning of the beam domain. This enables flexible control of the angular scanning of the radiation unit 1. The polyimide film layer 15 acts as an anchor layer, not only ensuring the stable alignment of the liquid crystal molecules when no voltage is applied, but also improving the sensitivity and accuracy of the liquid crystal layer 4's voltage response. According to actual needs, the bias voltage is adjusted to dynamically change the dielectric constant of the liquid crystal molecules, changing the signal radiation angle, thereby achieving control of signal transmission and reception.

[0061] In summary, the use of inverted microstrip helix and high-dielectric-constant ceramic radiation materials solves the problem of the existing liquid crystal microwave phased array antenna being unable to achieve wideband angle scanning; it not only improves the performance and flexibility of the antenna, but also reduces cost and power consumption, and enhances the antenna's integration and portability.

[0062] Specifically, the layered placement of the radiating structure and the liquid crystal phase shifter structure effectively resolves the performance issues associated with the inverted microstrip network due to the electric field coupling effect. The lower surface of the first glass substrate layer 2 is entirely copper-plated, and a coupling gap 13 is provided. This allows the radiating structure and the liquid crystal phase shifter structure to be efficiently coupled through the coupling gap 13, improving the antenna's radiation performance. Leveraging the reusability of the inverted spiral microstrip phase shifter layer 5, low-frequency power supply voltage and high-frequency signal sources are introduced into the structure. A bias circuit applies voltage to the antenna to change the dielectric constant of the liquid crystal, achieving beam control. By adopting a single-layer liquid crystal structure and a compact design layout, the antenna's flexibility and adaptability are greatly improved while maintaining high performance, effectively reducing the volume and weight of the antenna array and further enhancing the antenna's integration and portability.

[0063] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0064] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A broadband dielectric resonant liquid crystal microwave phased array antenna, characterized in that: include: Antenna units, each antenna unit comprising a radiation unit (1), a first glass substrate layer (2), a grounding copper layer (3), a liquid crystal layer (4), an inverted spiral microstrip phase shift layer (5), and a second glass substrate layer (6), wherein the radiation unit (1) is located on the upper surface of the first glass substrate layer (2), the grounding copper layer (3) is located on the lower surface of the first glass substrate layer (2), and a coupling gap (13) is provided on the grounding copper layer (3); The inverted spiral microstrip phase shift layer (5) is located on the upper surface of the second glass substrate layer (6); corresponding openings are provided on the inverted spiral microstrip phase shift layer (5) to allow electromagnetic waves to couple to the radiation unit (1); the liquid crystal layer (4) is composed of a high-strength epoxy resin encapsulated between the inverted spiral microstrip phase shift layer (5) and the grounding copper layer (3); and the inverted spiral microstrip phase shift layer (5) is immersed in the liquid crystal layer (4).

2. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 1, characterized in that: The radiation units (1) are arranged horizontally and vertically at equal intervals to form an array antenna. The array antenna has an axisymmetric structure in the vertical direction and a sequential structure in the horizontal direction. Each antenna unit is formed by cascading power dividers. The head end of the power divider is connected to a k connector to feed a high-frequency signal source. The phase of each antenna unit is independently controlled by a separately derived low-frequency AC bias line. The inverted spiral microstrip phase shift layer (5) and the grounding copper layer (3) of the antenna unit are energized by a bias circuit loaded on the upper surface of the second glass substrate layer (6). The grounding copper layer (3) serves as a negative electrode. The bias voltage control circuit is implemented on the periphery of the inverted spiral microstrip phase shift layer (5), and is connected to the antenna structure by an FPC soft strip line and connected to a power supply to achieve voltage supply.

3. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 2, wherein: The radiation unit (1) is made of a cubic high dielectric ceramic material and has two rectangular radiators of the same material on the upper side. Dielectric resonance generates higher-order modes outside the fundamental mode for widening the antenna bandwidth, and mode merging realizes a large-bandwidth antenna.

4. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 3, wherein: The radiation unit (1) has radiation characteristics different from those of a metal copper layer, and reduces antenna surface wave coupling in an array to achieve large-angle scanning.

5. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 4, characterized in that: The microstrip line of the inverted spiral microstrip phase shift layer (5) is a metal copper microstrip line with a characteristic impedance of 50 ohms, which is used for impedance matching with a standard 50 ohm coaxial line connector and is also matched with a 50 ohm impedance power divider in the array.

6. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 5, characterized in that: The head end of the inverted spiral microstrip phase shift layer (5) is connected to a high-frequency coupling structure (12) for passing high-frequency signals and blocking low-frequency voltages from entering the signal source. At the same time, a low-pass filter structure (11) is present on the array bias circuit for passing low-frequency signals and blocking high-frequency signals from entering the power supply.

7. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 6, characterized in that: The inverted spiral microstrip phase shift layer (5) and the bias circuit are both present on the upper surface of the second glass substrate layer (6), and the spiral microstrip multiplexing high-frequency signal circuit also serves as a voltage positive electrode for power feeding.

8. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 7, characterized in that: The coupling slot (13) is a rectangular slot structure of the ground copper layer (3), and the high-frequency signal at the tail end of the spiral line in the inverted spiral microstrip phase shift layer (5) is coupled to the radiation unit (1) through the coupling slot (13) and radiated out, and the coupling slot (13) is surrounded by a metal ground copper layer, and the metal ground copper layer is used as a bias negative electrode.

9. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 8, characterized in that: The inverted spiral microstrip phase shift layer (5) and the grounding copper layer (3) are bonded together by glue, the bonding layer is a high-strength epoxy resin layer, and the liquid crystal layer (4) is encapsulated therein.

10. The broadband dielectric resonant liquid crystal microwave phased array antenna according to claim 9, characterized in that: The liquid crystal layer (4) comprises a polyimide film layer (15), which is coated on the surfaces of the inverted spiral microstrip phase shift layer (5) and the grounding copper layer (3). Polymer microspheres (14) with a uniform diameter of 50 micrometers are present in the liquid crystal layer (4) to control the thickness of the liquid crystal layer (4).

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