Liquid crystal phase shifter and liquid crystal phased array antenna

Abstract

The invention provides a liquid crystal phase shifter and a liquid crystal phased array antenna. The liquid crystal phase shifter comprises a microstrip line, metal ground, liquid crystal and double-layer glass, wherein the microstrip line, the metal ground and the liquid crystal are positioned between the upper-layer glass and the lower-layer glass of the double-layer glass; the lower surface of the upper-layer glass is in contact with the upper surface of the microstrip line; the liquid crystal is clamped between the lower surface of the microstrip line and the upper surface of the metal ground; the metal ground is provided with a plurality of slots; and the lower surface of the metal ground is contacted with the upper surface of the lower-layer glass. The liquid crystal in the liquid crystal phase shifter is filled in the interlayer between the microstrip line and the metal ground, and the transmission delay of a signal on the microstrip line can be adjusted by changing the dielectric constant of the liquid crystal material, so that the phase modulation function is realized, and the functional requirements of a phased-array antenna can be met; the microstrip line and the metal ground in the liquid crystal phase shifter are simple in structure, miniaturization of the liquid crystal phase shifter can be achieved conveniently, and the requirement for the limited area of a unit channel in a phased-array antenna is met.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave phase shifting equipment, and in particular to a liquid crystal phase shifter and a liquid crystal phased array antenna. Background Art

[0002] Phased array antennas have high requirements for the time-frequency response, frequency selection, phase shift control, transmission matching and other performance of phase shifters. Phase shifters obtained using semiconductor technology have high power consumption and high cost, making them difficult to be widely used. Therefore, the existing technology has begun to integrate liquid crystal technology into phased array antennas, mainly classified into two scenarios: one is to directly apply liquid crystal holographic technology to the radiation unit of the phased array antenna, and the other is to use liquid crystal phase shifters.

[0003] However, in actual applications, liquid crystal phased array antennas based on liquid crystal holographic technology have high requirements for mechanical processing precision, are difficult to industrialize and have a low yield rate, which makes it difficult to control costs. Moreover, when holographic technology is directly applied to microwave radiation units, its bandwidth is too narrow, making it difficult to be widely used in the communication field that pursues broadband performance.

[0004] However, most of the current liquid crystal phase shifters are simple, similar to the planar structure of a planar capacitor, with low phase shift efficiency. To achieve the phase shift requirement of 0 to 360° (or 370°) (the basic requirement of most phased array antennas), a larger plane area is required to support it. When applied in millimeter wave, the plane area of ​​each unit will be even tighter, and the above-mentioned planar capacitor-type liquid crystal phase shifter cannot meet the performance and tight area requirements of the phased array antenna. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a liquid crystal phase shifter and a liquid crystal phased array antenna, in which the liquid crystal in the liquid crystal phase shifter is filled between a microstrip line and a metal ground, and the time delay of signal transmission on the transmission line can be adjusted by changing the dielectric constant of the liquid crystal material, thereby realizing the phase modulation function and meeting the performance requirements of the phased array antenna; the microstrip line and the metal ground in the liquid crystal phase shifter have a simple structure, which is convenient for miniaturizing the liquid crystal phase shifter and meeting the stringent requirements of the signal channel of the phased array antenna unit on the area; at the same time, the processing cost is low and it can be mass-produced.

[0006] In a first aspect, the present invention provides a liquid crystal phase shifter, the liquid crystal phase shifter comprising: a microstrip line, a metal ground, a liquid crystal and a double-layer glass;

[0007] The double-layer glass includes an upper layer of glass and a lower layer of glass, and a microstrip line, a metal ground, and liquid crystal are filled between the upper layer of glass and the lower layer of glass;

[0008] The lower surface of the upper glass layer contacts the upper surface of the microstrip line; liquid crystal is filled between the lower surface of the microstrip line and the upper surface of the metal ground; the metal ground is provided with a plurality of grooves; the lower surface of the metal ground contacts the upper surface of the lower glass layer.

[0009] Optionally, the groove of the metal ground is dumbbell-shaped, and the metal ground includes: a connecting portion, a first protruding portion and a second protruding portion, and the first protruding portion and the second protruding portion are connected through the connecting portion; liquid crystal is filled between the metal ground and the microstrip line, and the microstrip line spatially traverses the connecting portion corresponding to each groove structure in spatial position.

[0010] Optionally, the microstrip line and the metal ground are both copper conductors.

[0011] Optionally, the microstrip line is a planar copper line.

[0012] Optionally, the microstrip line includes a single main line and multiple short stubs; wherein the short stubs are vertically connected to the main line; liquid crystal is filled between the main line, the short stubs and the metal ground; and the short stubs are vertically arranged above adjacent grooves of the metal ground in terms of spatial position.

[0013] Optionally, the microstrip line includes an input matching region, an output matching region and a main body region; the size of the stub in the main body region is different from the size of the stub in the input matching region and the size of the stub in the output matching region;

[0014] The input matching region and the output matching region are located at two ends of the microstrip line, and the main body region is located between the input matching region and the output matching region.

[0015] Optionally, the stubs in the input matching region and the output matching region are mirror images of each other.

[0016] Optionally, the slots and the stubs are alternately arranged in space.

[0017] Optionally, the sizes of the slots in the main body region are different, and the sizes of the stubs in the main body region are different.

[0018] In a second aspect, the present invention provides a liquid crystal phased array antenna, in which the liquid crystal phase shifter mentioned in the first aspect is provided.

[0019] The present invention provides a liquid crystal phase shifter and a liquid crystal phased array antenna, the liquid crystal phase shifter includes: a microstrip line, a metal ground, a liquid crystal and a double layer of glass; wherein the double layer of glass includes an upper layer of glass and a lower layer of glass, the microstrip line, the metal ground and the liquid crystal are filled between the upper layer of glass and the lower layer of glass; the lower surface of the upper layer of glass is in contact with the upper surface of the microstrip line; the liquid crystal is filled between the lower surface of the microstrip line and the upper surface of the metal ground; the metal ground is provided with a plurality of slots; the lower surface of the metal ground is in contact with the upper surface of the lower layer of glass. The liquid crystal in the liquid crystal phase shifter is filled in the interlayer between the microstrip line and the metal ground, and the time delay of the signal transmitted on the microstrip line can be adjusted by changing the dielectric constant of the liquid crystal material, thereby realizing the phase shifting function, which can meet the functional requirements of the phased array antenna; the microstrip line and the metal ground in the liquid crystal phase shifter have a simple structure, which is convenient for miniaturization of the liquid crystal phase shifter, and meets the requirement of limited area of ​​unit channels in the phased array antenna; at the same time, the processing cost is low, and it can be mass-produced.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic structural diagram of a first liquid crystal phase shifter provided by an embodiment of the present invention;

[0024] Figure 2 A schematic structural diagram of a second liquid crystal phase shifter provided by an embodiment of the present invention;

[0025] Figure 3 A schematic structural diagram of a third liquid crystal phase shifter provided by an embodiment of the present invention;

[0026] Figure 4 A schematic structural diagram of a fourth liquid crystal phase shifter provided by an embodiment of the present invention;

[0027] Figure 5A schematic structural diagram of a fifth liquid crystal phase shifter provided in an embodiment of the present invention.

[0028] icon:

[0029] 10-microstrip line; 20-metal ground; 30-liquid crystal; 41-upper glass; 42-lower glass;

[0030] 21- slot; 21a- connection portion; 21b- first protruding portion; 21c- second protruding portion;

[0031] 11-main line; 12-stub line;

[0032] 10a-input matching area; 10b-output matching area; 10c-body area. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments below. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0034] Phased array antennas have high requirements for the time-frequency response, frequency selection, phase shift control, transmission matching and other performance of phase shifters. Phase shifters obtained using semiconductor technology have high power consumption and high cost, making them difficult to be widely used. Therefore, the existing technology has begun to integrate liquid crystal technology into phased array antennas, mainly classified into two scenarios: one is to directly apply liquid crystal holographic technology to the radiation unit of the phased array antenna, and the other is to use liquid crystal phase shifters.

[0035] Both types use a "sandwich" structure with liquid crystal filled between two layers of glass. By controlling the change in the dielectric constant of the liquid crystal, the structural capacitance and impedance are changed to achieve time-frequency response, frequency selection, phase shift control, transmission matching and other functions based on the variable capacitance structure.

[0036] However, in actual applications, liquid crystal phased array antennas based on liquid crystal holographic technology have high requirements for mechanical processing precision, are difficult to industrialize and have a low yield rate, which makes it difficult to control costs. Moreover, when holographic technology is directly applied to microwave radiation units, its bandwidth is too narrow, making it difficult to be widely used in the communication field that pursues broadband performance.

[0037] However, most of the current liquid crystal phase shifters are simple planar structures with low phase shift efficiency. To achieve the phase shift requirement of 0 to 360° (or 370°) (the basic requirement of most phased array antennas), a larger plane area is needed to support it. Especially in the application of millimeter waves, the plane area of ​​each unit will be even more limited, making it impossible to meet the phase shift range required by the phased array antenna when using liquid crystal as a phase shift material. Based on this, the present invention provides a liquid crystal phase shifter and a liquid crystal phased array antenna. The liquid crystal in the liquid crystal phase shifter is filled between the microstrip line and the metal ground. The time delay of the signal transmission on the microstrip line can be adjusted by changing the dielectric constant of the liquid crystal material, thereby realizing the phase adjustment function and meeting the functional requirements of the phased array antenna; the microstrip line and the metal ground in the liquid crystal phase shifter have a simple structure, which is convenient for miniaturization of the liquid crystal phase shifter and meets the requirement of limited area of ​​the unit channel in the phased array antenna; at the same time, the processing cost is low and it can be mass-produced.

[0038] To facilitate understanding of this embodiment, a liquid crystal phase shifter disclosed in an embodiment of the present invention is first described in detail. Figure 1 The structural schematic diagram of the first liquid crystal phase shifter shown includes: a microstrip line 10, a metal ground 20, a liquid crystal 30 and a double-layer glass; wherein the double-layer glass includes an upper glass 41 and a lower glass 42, and the microstrip line 10, the metal ground 20 and the liquid crystal 30 are located between the upper glass 41 and the lower glass 42. The lower surface of the upper glass 41 is in contact with the upper surface of the microstrip line 10; the liquid crystal 30 is filled between the lower surface of the microstrip line 10 and the upper surface of the metal ground 20; a plurality of grooves are provided on the metal ground 20; the lower surface of the metal ground 20 is in contact with the upper surface of the lower glass 42. The liquid crystal 30 is filled between the microstrip line 10 and the metal ground 20; the lower surface of the metal ground 20 is in contact with the upper surface of the lower glass 42.

[0039] Specifically, the overall structure of the liquid crystal phase shifter consists of five layers, including upper and lower glass layers, a liquid crystal material layer in the middle, a microstrip line layer, and a microstrip line metal layer. The liquid crystal material is filled in the interlayer between the microstrip line structure and the metal floor. The time delay of the signal transmission on the microstrip line can be adjusted by changing the dielectric constant of the liquid crystal material, thereby realizing the phase modulation function.

[0040] like Figure 2 In the structural schematic diagram of the second liquid crystal phase shifter shown in the figure, a plurality of slots 21 are arranged on the metal ground 20, and liquid crystal 30 is sandwiched between the slots 21 and the microstrip line 10. The slots 21 are dumbbell-shaped, including: a connecting portion 21a, a first protruding portion 21b and a second protruding portion 21c, and the first protruding portion 21b and the second protruding portion 21c are connected through the connecting portion 21a; the liquid crystal 30 is filled between the connecting portion 21a and the microstrip line 10, and the microstrip line 10 traverses the connecting portion 21a corresponding to each slot 21 in terms of spatial position.

[0041] Optionally, the microstrip line 10 and the metal ground 20 are both copper conductors.

[0042] Optionally, the microstrip line 10 is a planar copper line.

[0043] Figure 2 The microstrip line 10 in the liquid crystal phase shifter is a single planar copper line, and the microstrip line in the two glass layers is a through structure. In order to shorten the actual length of the microstrip line, a number of slotted structures are added to the metal ground along the microstrip line. These slotted structures can make the current equivalent to increasing the electrical length of the signal when passing through the slots. The working principle of this type of structure is similar to that of a low-pass filter.

[0044] like Figure 3 As shown, in order to further shorten the length of the entire structure and make the structure more compact, optionally, the microstrip line 10 includes a single main line 11 and multiple short stubs 12; wherein the short stubs 12 are vertically connected to the main line 11; the liquid crystal 30 is filled between the main line 11, the short stubs 12 and the metal ground 20; the main line 11 runs through the center of the dumbbell of each slot 21 on each metal ground 20 in spatial position; the short stubs 12 are arranged between adjacent slots 21 in spatial position.

[0045] Short stubs 12 are added on both sides of the microstrip line 10 conductor. The short stubs 12 are spatially located between every two slots 21 on the metal ground 20 to form a "loaded short stub microstrip line". Liquid crystal 30 is filled between the loaded short stub microstrip line and the metal ground with a slotted structure to produce a "loaded short stub microstrip line liquid crystal phase shifter".

[0046] The reason why the short stub structure is designed in this specific position (in the middle of the groove on the metal floor) is that the change in the dielectric constant of the liquid crystal only occurs in the part with the metal floor, and not in the part with the groove on the floor. Its effect is equivalent to adding the "extra" delay generated when the electromagnetic wave signal passes through, so that the "stub-loaded" liquid crystal phase shifter can be arranged into a limited unit channel area.

[0047] The liquid crystal is "driven" by applying a bias voltage to the microstrip line, changing its dielectric constant.

[0048] In layman's terms, this method of adding a short stub to the microstrip line and slotting the metal ground can be called the "loaded stub" method. The "loaded stub" microstrip line structure, combined with the slotted metal ground and the liquid crystal filled between the two, can make the overall structure of the liquid crystal phase shifter more compact, and can generate sufficient phase offset in a limited phased array antenna unit area to achieve the overall function of the phased array antenna.

[0049] In order to make this "loaded stub" structure better used in application scenarios with different bandwidth requirements, the mechanical structure of the stub can be appropriately adjusted, such as optimizing its length, width, position and other parameters to meet the requirements of different bandwidths. Figure 4 As shown, optionally, the microstrip line 10 includes an input matching area 10a, an output matching area 10b and a main body area 10c; the size of the short line in the main body area 10c may be different from the size of the short line in the input matching area 10a and the output matching area 10b, and may be the same in some scenarios; wherein the input matching area 10a and the output matching area 10b are located at both ends of the microstrip line 10, and the main body area 10c is located between the input matching area 10a and the output matching area 10b.

[0050] For example, when the operating frequency band of the phased array antenna corresponding to the liquid crystal phase shifter is 17.30-21.20 GHz, the first three and last three stub structures can be adjusted in size and position. At this time, the stubs in the input matching area 10a and the output matching area 10b are mirror images of each other. The size of the slots 21 in the main area 10c is the same, and the size of the stubs 12 in the main area 10c is the same. Similarly, similar bandwidth matching can be achieved by changing the period and size of the slots on the floor.

[0051] The overall size of the phase shifter is reduced by using the periodic layout of the "loaded stubs" of the microstrip line combined with appropriate size adjustment. This method of "loaded stubs" composed of periodic units can effectively reduce the overall unit structure of the liquid crystal phase shifter, which is particularly applicable in the field of phased arrays (especially millimeter wave phased arrays) where space is tight.

[0052] like Figure 5 As shown, optionally, the size of the slots 21 in the main body region 10c may be different, and the size of the stubs 12 in the main body region 10c may also be different. Figure 5 The structure shown has appropriate non-repetitive structures and size changes in the main area, which increases the complexity of the structural design, but provides greater freedom in design and also makes it feasible to achieve a larger phase shift within the same period unit.

[0053] It can be seen that the liquid crystal phase shifter in the above embodiment has the following technical effects:

[0054] 1. It can realize the miniaturization of liquid crystal phase shifter;

[0055] 2. Enable liquid crystal phase shifters to be truly applied in flat-panel phased array antennas, especially in millimeter wave communication applications;

[0056] 3. It can effectively meet the needs of communication equipment for different bandwidths, especially making special contributions to broadband communication equipment;

[0057] 4. Low processing cost. The processing technology used in this "loaded stub microstrip" liquid crystal phase shifter is basically the same as the current mature processing technology of liquid crystal displays, and there is no need for additional equipment investment;

[0058] 5. Like LCD displays, it is suitable for mass production.

[0059] In summary, the liquid crystal in the liquid crystal phase shifter is filled between the microstrip line and the metal ground, and the time delay of the signal transmission on the transmission line can be adjusted by changing the dielectric constant of the liquid crystal material, thereby realizing the phase modulation function, which can meet the performance requirements of the phased array antenna; the structure of the microstrip line and the metal ground in the liquid crystal phase shifter is simple, which is convenient for miniaturization of the liquid crystal phase shifter and meets the area requirements of the phased array antenna; at the same time, the processing cost is low and it can be mass-produced.

[0060] An embodiment of the present invention further provides a liquid crystal phased array antenna, in which the liquid crystal phase shifter mentioned in the above embodiment is disposed.

[0061] The liquid crystal phased array antenna provided in the embodiment of the present invention has the same implementation principle and technical effect of the liquid crystal phase shifter as those in the aforementioned liquid crystal phase shifter embodiment. For the sake of brief description, for parts not mentioned in this embodiment, reference may be made to the corresponding contents in the aforementioned liquid crystal phase shifter embodiment.

[0062] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0063] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0064] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0065] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present invention can essentially or in other words, the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, electronic device, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0066] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A liquid crystal phase shifter, characterized in that: The liquid crystal phase shifter comprises: a microstrip line, a metal ground, a liquid crystal and a double-layer glass; Wherein, the double-layer glass comprises an upper layer of glass and a lower layer of glass, and the microstrip line, the metal ground, and the liquid crystal are filled between the upper layer of glass and the lower layer of glass; The lower surface of the upper glass layer contacts the upper surface of the microstrip line; the liquid crystal is filled between the lower surface of the microstrip line and the upper surface of the metal ground; the metal ground is provided with a plurality of grooves; the lower surface of the metal ground contacts the upper surface of the lower glass layer.

2. The liquid crystal phase shifter according to claim 1, characterized in that: The groove of the metal ground is dumbbell-shaped, and the metal ground includes: a connecting portion, a first protruding portion and a second protruding portion, and the first protruding portion and the second protruding portion are connected through the connecting portion; the liquid crystal is filled between the metal ground and the microstrip line, and the microstrip line spatially traverses the connecting portion corresponding to each of the groove structures.

3. The liquid crystal phase shifter according to claim 1, characterized in that: The microstrip line and the corresponding metal ground are both copper conductors.

4. The liquid crystal phase shifter according to claim 3, characterized in that: The microstrip line is a planar copper line.

5. The liquid crystal phase shifter according to claim 3, characterized in that: The microstrip line includes a single main line and multiple short stubs; wherein the short stubs are vertically connected to the main line; the liquid crystal is filled between the main line, the short stubs and the metal ground; the short stubs are vertically arranged above adjacent grooves of the metal ground in terms of spatial position.

6. The liquid crystal phase shifter according to claim 5, characterized in that: The microstrip line comprises an input matching region, an output matching region and a main body region; the size of the stub in the main body region is different from the sizes of the stub in the input matching region and the output matching region; The input matching region and the output matching region are located at two ends of the microstrip line, and the main body region is located between the input matching region and the output matching region.

7. The liquid crystal phase shifter according to claim 6, characterized in that: The stubs in the input matching region and the output matching region are mirror images of each other.

8. The liquid crystal phase shifter according to claim 6, characterized in that: The slots and the stubs in the main body region are alternately arranged in space.

9. The liquid crystal phase shifter according to claim 6, characterized in that: The slots in the body region have different sizes, and the stubs in the body region have different sizes.

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

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