Liquid crystal phased array antenna unit and array

Abstract

The invention discloses a liquid crystal phased-array antenna unit and array, and relates to the technical field of microwave antennae, and the disclosed liquid crystal phased-array antenna unit comprises a feed module, a radiation module connected with the feed module, and a voltage bias module connected with the radiation module; wherein the feed module is coupled with the phase shifter of the radiation module. The voltage bias module is connected with the phase shifter through a bias line, and a double-fan-shaped branch isolation module is further arranged between the bias line and the phase shifter. The double-fan-shaped branch isolation module is used for isolating a radio frequency signal transmitted by the feed module and a voltage bias signal transmitted by the voltage bias module. The isolation module of the double-fan-shaped branch knot structure is used for achieving isolation of radio frequency signals, and compared with a radio frequency isolation wire, the isolation module of the double-fan-shaped branch knot structure has a higher bandwidth, so that a good radio frequency isolation effect is achieved in a wide frequency band.

Description

Technical Field

[0001] This application relates to the technical field of microwave antennas, and particularly to a liquid crystal phased array antenna unit and array. Background Art

[0002] With the rapid development of information technology, wireless communication systems need to have characteristics such as large capacity, multi-function, and ultra-wideband. The phased array antenna based on liquid crystal materials has great application prospects in the future beam scanning field. At present, the phased array antenna based on liquid crystal materials mainly powers the antenna unit through a bias line. For a small-sized liquid crystal phased array antenna, the bias line on the antenna unit will greatly affect the performance of the antenna unit, thereby affecting the overall antenna array.

[0003] In related technologies, a radio frequency isolation line is usually used to eliminate the influence of the bias line on the performance of the antenna unit, that is, to reduce the radio frequency signal on the bias line. However, the radio frequency isolation line itself is a narrowband structure, and its performance is greatly affected by the radio frequency signal frequency, resulting in an unstable isolation effect of the radio frequency isolation line. Summary of the Invention

[0004] The main purpose of this application is to provide a liquid crystal phased array antenna unit and array, aiming to solve the technical problem that the isolation effect of the radio frequency isolation line in related technologies is not stable.

[0005] To achieve the above object, this application proposes a liquid crystal phased array antenna unit, which is characterized in that the liquid crystal phased array antenna unit includes a feeding module, a radiation module connected to the feeding module, and a voltage bias module connected to the radiation module; wherein,

[0006] The feeding module is coupled to the phase shifter of the radiation module; the voltage bias module is connected to the phase shifter through a bias line, and a double-sector stub isolation module is also arranged between the bias line and the phase shifter;

[0007] The double-sector stub isolation module is used to isolate the radio frequency signal transmitted by the feeding module and the voltage bias signal transmitted by the voltage bias module.

[0008] In one embodiment, the double-sector stub isolation module is arranged at a quarter waveguide wavelength λ away from the connection point of the phase shifter and the bias line;

[0009] The double-sector stub isolation module includes two symmetrically arranged sector stubs; the central angle of the sector stub is 38°.

[0010] In one embodiment, a phase shifter, a double-sector stub isolation module, and a bias line are disposed on a phase shift layer of a radiation module. A first dielectric substrate, a ground plane, and a liquid crystal layer are sequentially disposed above the phase shift layer from top to bottom. A radiation patch is further disposed on the upper surface of the first dielectric substrate. A second dielectric substrate is disposed below the phase shift layer. Among them, coupling slits are disposed at the centers of both the liquid crystal layer and the ground plane.

[0011] The phase shift layer is configured to shift the phase of a radio frequency signal and then couple the radio frequency signal to the radiation patch through the coupling slit.

[0012] In one embodiment, the radiation patch is a square metal sheet; a pair of diagonals in the radiation patch are chamfered.

[0013] The radiation patch is used for circular polarization radiation of radio frequency signals.

[0014] In one embodiment, both the first dielectric substrate and the second dielectric substrate are glass substrates; the thicknesses of both the first dielectric substrate and the second dielectric substrate are 0.7 mm, and the relative dielectric constants are both 5.15.

[0015] In one embodiment, the thickness of the liquid crystal layer is 0.05 mm, and the adjustment range of the relative dielectric constant of the liquid crystal layer is between 2.45 and 3.5.

[0016] In one embodiment, the relative dielectric constant of the liquid crystal layer is adjusted by a voltage bias signal.

[0017] In one embodiment, the liquid crystal phased array antenna unit further includes a reflecting floor, and the reflecting floor is disposed below the second dielectric substrate.

[0018] The reflecting floor is used to reflect the backward energy of radio frequency signals.

[0019] In one embodiment, the thicknesses of both the ground plane and the radiation patch are 0.003 mm.

[0020] To achieve the above object, the present application further provides a liquid crystal phased array antenna array, and the liquid crystal phased array antenna array is composed of liquid crystal phased array antenna units according to any one of claims 1-9.

[0021] One or more technical solutions proposed by the present application have at least the following technical effects:

[0022] The liquid crystal phased array antenna unit and array provided by the present application effectively isolate the radio frequency signal transmitted by the feeding module and the voltage bias signal transmitted by the voltage bias module by introducing a double-sector stub isolation module, thereby significantly improving the isolation stability of the radio frequency signal. Compared with the traditional narrowband radio frequency isolation line, the double-sector stub isolation module of the present application has a wider operating bandwidth and a more stable isolation effect, and can effectively reduce the influence of the bias line on the performance of the antenna unit. Description of the Drawings

[0023] The accompanying drawings here are incorporated into and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the related art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the related art. Obviously, for those of ordinary skill in the art, other accompanying drawings can also be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a schematic diagram of module connections for the first embodiment of the liquid crystal phased array antenna unit of this application.

[0026] Figure 2 (a) is a schematic structural diagram of a specific implementation of radiation module one of the liquid crystal phased array antenna unit in the first embodiment. Figure 2 (b) is a detailed diagram of the phase shift layer of the radiation module.

[0027] Figure 3 (a) is a radiation gain curve graph of the radio frequency isolation line from 18 GHz to 20 GHz in the first embodiment. Figure 3 (b) is a radiation gain curve graph of the double-sector branch.

[0028] Figure 4 It is a radiation gain change graph when the relative dielectric constant of the liquid crystal layer is 2.45 and the dielectric constant is 3.5 in the first embodiment.

[0029] Figure 5 It is a radiation characteristic curve graph of the radiation module at 19 GHz.

[0030] Explanation of the reference numerals in the accompanying drawings:

[0031] 1 Radiation patch, 2 First dielectric substrate, 3 Ground plane, 4 Liquid crystal layer, 5 Phase shifter, 6 Bias line, 7 Double-sector branch isolation module, 8 Second dielectric substrate, 9 Air layer, 10 Reflection floor.

[0032] The realization of the purpose, functional features, and advantages of this application will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed implementation manners

[0033] It should be understood that the specific embodiments described here are only used to explain the technical solutions of this application and are not used to limit this application.

[0034] To better understand the technical solutions of this application, the following will be described in detail in conjunction with the accompanying drawings of the specification and the specific implementation manners.

[0035] With the development of millimeter-wave antenna technology, miniaturized array antennas have gradually come into people's view. Millimeter-wave antennas have a narrow beam and good directivity. Through the interference and superposition effects of multiple antenna elements, millimeter-wave array antennas can form a directional beam to achieve precise positioning and communication.

[0036] As a passive medium, liquid crystal has a small density and light weight, and at the same time has a large power capacity and continuous good tunability. Phased array antennas based on liquid crystal materials have great application prospects in the future beam scanning field.

[0037] Currently, phased array antennas based on liquid crystal materials are mainly powered by bias lines to the antenna elements. For small-sized liquid crystal phased array antennas, the bias lines on the elements will largely affect the performance of the antenna elements, thereby affecting the overall array antenna.

[0038] In related technologies, to eliminate the influence of bias lines on the performance of liquid crystal phased array antenna elements, radio frequency isolation lines are often used. Since the radio frequency isolation line is a narrowband structure and its performance varies greatly with frequency, the isolation effect of the radio frequency isolation line is not stable.

[0039] This application provides a solution. The isolation module with a double-sector stub structure is used to isolate radio frequency signals. Compared with the radio frequency isolation line in related technologies, it has a higher bandwidth, enabling good radio frequency isolation effects in a relatively wide frequency band, and thus ensuring the gain stability of the antenna elements in a relatively wide frequency band.

[0040] Based on this, an embodiment of this application provides a liquid crystal phased array antenna element. Refer to Figure 1 , Figure 1 which is a schematic diagram of module connections for the first embodiment of the liquid crystal phased array antenna element of this application.

[0041] In this embodiment, the liquid crystal phased array antenna element includes a feeding module, a radiation module connected to the feeding module, and a voltage bias module connected to the radiation module; among them,

[0042] the feeding module is coupled to the phase shifter of the radiation module; the voltage bias module is connected to the phase shifter through a bias line, and a double-sector stub isolation module is also arranged between the bias line and the phase shifter;

[0043] The double-sector stub isolation module is used to isolate the radio frequency signal transmitted by the feeding module and the voltage bias signal transmitted by the voltage bias module.

[0044] It should be noted that the feeding module is used to provide a radio frequency signal for the radiation module. The radiation module is used to radiate the radio frequency signal externally. The voltage bias module is connected to the phase shifter of the radiation module through a bias line to provide a voltage bias signal for the phase shifter of the radiation module, so that the phase shifter adjusts the phase of the radio frequency signal through the voltage bias signal.

[0045] In addition, it should be noted that the double-sector stub isolation module is used to isolate the radio frequency signal transmitted by the feed module and the voltage bias signal transmitted by the voltage bias module to prevent mutual interference between the radio frequency signal and the voltage bias signal, and ensure the integrity of the radio frequency signal and the accuracy of the voltage bias signal. It can be understood that if the radio frequency signal flows into the bias line, a large inductance will be formed in the bias line, causing radio frequency impedance mismatch and reducing the radiation efficiency of the radiation module. In this embodiment, the double-sector stub isolation module is used to isolate the radio frequency signal to ensure the radiation quality of the radiation module. At the same time, compared with the traditional radio frequency isolation line, the double-sector structure has a wider bandwidth, thereby ensuring the gain stability of the radiation module within a wider frequency band.

[0046] Further, referring to Figure 2 , Figure 2 is a schematic structural diagram of a specific embodiment of the radiation module of the liquid crystal phased array antenna unit in this embodiment.

[0047] In this embodiment, the phase shifter 5, the double-sector stub isolation module 7 and the bias line 6 are arranged on the phase shift layer of the radiation module. Above the phase shift layer, a first dielectric substrate 2, a ground plane 3 and a liquid crystal layer 4 are arranged in sequence from top to bottom. A radiation patch 1 is also arranged on the upper surface of the first dielectric substrate 2; a second dielectric substrate 8 is arranged below the phase shift layer; wherein, coupling slits are arranged at the centers of both the liquid crystal layer 4 and the ground plane 3.

[0048] Among them, the phase shift layer is used to shift the radio frequency signal and then couple the radio frequency signal to the radiation patch 1 through the coupling slit.

[0049] The double-sector stub isolation module includes two symmetrically arranged sector stubs, and the central angle of the sector stub is 38°.

[0050] The radiation patch 1 is a square metal sheet, and a pair of diagonals in the radiation patch are chamfered. The radiation patch is used for circular polarization radiation of the radio frequency signal.

[0051] Both the first dielectric substrate and the second dielectric substrate are glass substrates, and the thicknesses of both the first dielectric substrate and the second dielectric substrate are 0.7 mm, and the relative dielectric constants are both 5.15.

[0052] The thickness of the liquid crystal layer is 0.05 mm, and the adjustment range of the relative dielectric constant of the liquid crystal layer is between 2.45 and 3.5. The liquid crystal layer adjusts the relative dielectric constant through the voltage bias signal.

[0053] The liquid crystal phased array antenna unit further includes a reflection floor, and the reflection floor is arranged below the second dielectric substrate. The reflection floor is used to reflect the backward energy of the radio frequency signal. The thicknesses of both the ground plane and the radiation patch are 0.003 mm.

[0054] Specifically, as Figure 2 (a) shows, the radiation module of the liquid crystal phased array antenna unit is sequentially provided with a first dielectric substrate 2, a ground plane 3, a liquid crystal layer 4, a phase shifter 5, a bias line 6, a double-sector stub isolation module 7, a second dielectric substrate 8, and a reflecting ground plane 10 from top to bottom. Among them, a radiation patch 1 is arranged on the upper surface of the first dielectric substrate 2, and an air layer 9 is filled between the second dielectric substrate 8 and the reflecting ground plane 10.

[0055] Among them, coupling slits are provided at the centers of both the ground plane 3 and the liquid crystal layer 4. The feeding module first couples the radio frequency signal to the microstrip line connected to the phase shifter 5, and directly powers the phase shifter through the coupling slit, which can make the overall antenna more compact, thereby reducing the antenna profile.

[0056] The phase shifter 5 then couples the radio frequency signal to the radiation patch 1 through the coupling slits of the ground plane 3 and the liquid crystal layer 4 to achieve the radiation of the radio frequency signal.

[0057] As Figure 2 (b) shows, the phase shift layer is provided with a phase shifter 5 and a bias line 6 connected to each other, and a double-sector stub isolation module 7 is arranged at a distance of 1 / 4 waveguide wavelength λ from the connection point of the phase shifter 5 and the bias line 6.

[0058] The double-sector stub isolation module 7 includes two symmetrically arranged sector stubs. The central angle of a single sector stub is 38°, and the radius is 0.78 mm. It is arranged at a distance of 1 / 4λ from the connection point of the phase shifter and the bias line. When the radio frequency signal is transmitted to the double-sector stub, the double-sector stub is equivalent to a band-stop filter, blocking the transmission of the radio frequency signal in a certain frequency band, thereby realizing the isolation of radio frequency direct current. Furthermore, the radiation effect of the radiation module is ensured. Specifically, as Figure 3 shown, Figure 3 shows the radiation gain curve of the radio frequency signal from 18 GHz to 20 GHz (the abscissa is the frequency f, and the ordinate is the realized gain). Among them, Figure 3 (a) is the radiation gain curve of the radio frequency isolation line from 18 GHz to 20 GHz, Figure 3 (b) is the radiation gain curve of the double-sector stub.

[0059] It can be seen that within the range of dielectric constant variation, compared with the radio frequency isolation line, the radiation gain with the addition of the double-sector stub can remain stable in this frequency band.

[0060] The dielectric constant of the liquid crystal layer is controlled by a voltage bias signal. Specifically, the liquid crystal layer 4 is subjected to an alignment treatment. When no voltage bias signal is applied, the liquid crystal molecules are aligned in the same direction. When a bias voltage is applied to the phase shifter 5, the liquid crystal molecules are deflected, the dielectric constant of the liquid crystal material changes, and the resonant frequency of the corresponding liquid crystal cell changes, thereby realizing the adjustment of the radiation characteristics. A long microstrip phase shifter is adopted below the liquid crystal layer 4, and a voltage bias signal is directly added to the phase shifter through a bias line, thereby changing the dielectric constant of the liquid crystal layer. After verification, in this embodiment, a liquid crystal layer with a relative dielectric constant adjustment range of 2.45 to 3.5 is adopted. When the relative dielectric constant of the liquid crystal layer is between 2.45 and 3.5, a 360° phase modulation range can be achieved.

[0061] Referring to Figure 4 , Figure 4 (The abscissa is the phase modulation angle, and the ordinate is the actual gain) shows the radiation gain change diagrams of the liquid crystal phased array antenna element when radiating a 19 GHz RF signal with a relative dielectric constant of 2.45 and a dielectric constant of 3.5 for the liquid crystal layer.

[0062] At 19 GHz, the maximum gain difference between a relative dielectric constant of 2.45 and a dielectric constant of 3.5 is only 0.3 dB, which indicates that the double-sector stub isolation module has a good RF signal isolation effect and will not cause too much change in the radiation gain due to the change in the dielectric constant.

[0063] The shape of the radiation patch 1 is square, with a size of 0.2λ. One pair of diagonals of the patch is chamfered, and the chamfer size is 0.0038λ. This design realizes the circular polarization radiation of the RF signal.

[0064] To improve the antenna gain and reduce the antenna backward radiation, a reflector floor 10 is added 1 mm behind the second dielectric substrate 8 to reflect the backward energy.

[0065] In this embodiment, the thickness of the liquid crystal layer 4 is 0.05 mm. Both the first glass substrate 2 and the second glass substrate 8 are made of glass substrates with a relative dielectric constant of 5.15 and a thickness of 0.7 mm. The thicknesses of the upper patch 1 and the microstrip line are both 0.003 mm. The thickness of the radiation module composed of all the structures is only 9.5 mm.

[0066] It can be understood that in this example, the feeding structure adopts slot coupling feeding. First, the RF signal is coupled to the phase shifter 5. After being phase-shifted by the phase shifter 5, it is then coupled to the upper patch 1 through a slot for radiation. By applying a voltage to the phase shifter 5, the dielectric constant of the liquid crystal layer can be independently controlled.

[0067] Such as Figure 5As shown, the radiation characteristics of the radiation module of this embodiment at 19 GHz were tested. Its reflection coefficient S11 is matched in the range of 18 GHz to 20 GHz. Under different dielectric constants, it is basically lower than -10 dB, with good matching, which can ensure good matching effects when adjusting the phase after unit arraying.

[0068] The antenna described in this embodiment uses liquid crystal as the dielectric substrate. Compared with the electronic tuning devices commonly used in current array antenna units, liquid crystal has the characteristic of continuous adjustability, enabling the formed array antenna to have more accurate continuous scanning characteristics. At the same time, compared with other phase change materials such as graphene and vanadium dioxide, the preparation of liquid crystal is more convenient, and the variation law between the relative dielectric constant of the liquid crystal substrate and voltage is stable.

[0069] Furthermore, the second embodiment of the present application provides a liquid crystal phased array antenna array, which is composed of the above-mentioned liquid crystal phased array antenna units.

[0070] In this embodiment, the control circuit of the liquid crystal phased array antenna array calculates the required offset phase and the corresponding bias voltage value for each liquid crystal phased array antenna unit according to the reflection array phase compensation principle and the required antenna beam azimuth angle, and applies the bias voltage to each unit through the voltage bias module of each liquid crystal phased array antenna unit.

[0071] The planar array antenna unit based on liquid crystal material has multiple switchable states and high phase accuracy, which can improve the angle scanning accuracy and range of the formed array antenna.

[0072] The above are only some embodiments of the present application, and thus do not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application by using the content of the specification and drawings of the present application, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A liquid crystal phased array antenna unit, characterized in that: The liquid crystal phased array antenna unit includes a feeding module, a radiation module connected to the feeding module, and a voltage bias module connected to the radiation module; wherein, The feeding module is coupled to the phase shifter of the radiation module; the voltage bias module is connected to the phase shifter through a bias line, and a double-sector branch isolation module is also provided between the bias line and the phase shifter; The dual-fan branch isolation module is used to isolate the radio frequency signal transmitted by the feeding module and the voltage bias signal transmitted by the voltage bias module.

2. The liquid crystal phased array antenna unit according to claim 1, characterized in that: The double-fan-shaped branch isolation module is arranged at a distance of one quarter of the waveguide wavelength λ from the connection point between the phase shifter and the bias line; The double-fan-shaped branch isolation module includes two symmetrically arranged fan-shaped branches; the central angle of the fan-shaped branches is 38°.

3. The liquid crystal phased array antenna unit according to claim 1, characterized in that: The phase shifter, the double-sector branch isolation module and the bias line are arranged on the phase shift layer of the radiation module, and a first dielectric substrate, a grounding plate and a liquid crystal layer are arranged above the phase shift layer from top to bottom, and a radiation patch is also arranged on the upper surface of the first dielectric substrate; a second dielectric substrate is arranged below the phase shift layer; wherein coupling gaps are arranged at the centers of the liquid crystal layer and the grounding plate; The phase shift layer is used to shift the phase of the radio frequency signal and then couple the radio frequency signal to the radiation patch through the coupling gap.

4. The liquid crystal phased array antenna unit according to claim 3, characterized in that: The radiation patch is a square metal sheet; a pair of diagonal corners of the radiation patch are chamfered; The radiation patch is used for circularly polarized radiation of the radio frequency signal.

5. The liquid crystal phased array antenna unit according to claim 3, characterized in that: The first dielectric substrate and the second dielectric substrate are both glass substrates; the thickness of the first dielectric substrate and the second dielectric substrate are both 0.7 mm, and the relative dielectric constant is both 5.

15.

6. The liquid crystal phased array antenna unit according to claim 3, characterized in that: The thickness of the liquid crystal layer is 0.05 mm, and the relative dielectric constant of the liquid crystal layer can be adjusted in a range of 2.45 to 3.

5.

7. The liquid crystal phased array antenna unit according to claim 6, characterized in that: The liquid crystal layer adjusts the relative dielectric constant through the voltage bias signal.

8. The liquid crystal phased array antenna unit according to claim 3, characterized in that: The liquid crystal phased array antenna unit further includes a reflective floor, and the reflective floor is arranged below the second dielectric substrate; The reflective floor is used to reflect backward energy of the radio frequency signal.

9. The liquid crystal phased array antenna unit according to claim 3, characterized in that: The thickness of the ground plate and the radiation patch are both 0.003 mm.

10. A liquid crystal phased array antenna array, characterized in that: The liquid crystal phased array antenna array is composed of the liquid crystal phased array antenna unit according to any one of claims 1 to 9.

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