阅读说明：本技术 枝节加载的快速响应型电调谐液晶移相器 (Quick response type electric tuning liquid crystal phase shifter with branch loading ) 是由 苏治国 王其鹏 殷弋帆 于 2021-08-27 设计创作，主要内容包括：本发明提供了一种枝节加载的快速响应型电调谐液晶移相器,包括第一介质基材、液晶基材及第二介质基材,所述的第一介质基材、液晶基材和第二介质基材依次叠合在一起；所述的第一介质基材的下表面设置有上导体层,所述的第二介质基材的上表面设置有下导体层。该液晶移相器具有品质因数高、偏置线阻抗高、工艺上易于实现、可量产、损耗低、便于小型化、和阵列集成等特点。(The invention provides a quick response type electrically tuned liquid crystal phase shifter with branch loading, which comprises a first medium base material, a liquid crystal base material and a second medium base material, wherein the first medium base material, the liquid crystal base material and the second medium base material are sequentially stacked together; the lower surface of the first dielectric substrate is provided with an upper conductor layer, and the upper surface of the second dielectric substrate is provided with a lower conductor layer. The liquid crystal phase shifter has the characteristics of high quality factor, high bias line impedance, easiness in realization of the process, mass production, low loss, convenience in miniaturization, array integration and the like.)

1. A quick response type electric tuning liquid crystal phase shifter with branch loading is characterized in that: the liquid crystal display panel comprises a first medium base material (1), a liquid crystal base material (2) and a second medium base material (3), wherein the first medium base material (1), the liquid crystal base material (2) and the second medium base material (3) are sequentially stacked together;

an upper conductor layer (14) is arranged on the lower surface of the first dielectric substrate (1), and the upper conductor layer (14) comprises a central conductor (10), a left coplanar waveguide (11), a right coplanar waveguide (12), a feed pad (13) and a bias line (130);

the left coplanar waveguide (11) consists of a first conduction band (111) and a first ground plate (112) which is symmetrically arranged on two sides of the first conduction band by taking the first conduction band as a center;

the right coplanar waveguide (12) consists of a second conduction band (121) and a second ground plate (122) which is symmetrically arranged on two sides of the second conduction band by taking the second conduction band as a center;

the central conductor (10) is located between the left coplanar waveguide (11) and the right coplanar waveguide (12) and is connected to the first conduction band (111) of the left coplanar waveguide (11) and to the second conduction band (121) of the right coplanar waveguide (12);

the feeding pad (13) is positioned at the lower edge of the right side of the first dielectric substrate (1) and is connected with the central conductor (10) through a bias line (130); the left coplanar waveguide (11) and the right coplanar waveguide (12) have the same structure, and the first ground plate (31) of the left coplanar waveguide (11) is gradually opened, so that the gap between the first ground plate (31) of the left coplanar waveguide and the first conduction band (111) of the left coplanar waveguide is gradually enlarged;

a lower conductor layer (30) is arranged on the upper surface of the second dielectric substrate (3), the lower conductor layer (30) comprises a first grounding plate (31) and a second grounding plate (32), and a gap (33) exists between the first grounding plate (31) and the second grounding plate (32); etching a slot (311) on the first grounding plate (31) along the vertical projection of the bias line (130), wherein a plurality of first grounding equipotential lines (34) are arranged along the slot (311) and cross over the slot (311); a second grounding equipotential line (35) is arranged at a position which crosses the gap (33) and is close to the slot (311), and the second grounding equipotential line (35) is connected with the first grounding plate (31) and the second grounding plate (32);

the edge of the first grounding plate (31) close to the gap (33) is provided with a plurality of upper branches (312), the edge of the second grounding plate (32) close to the gap (33) is provided with a plurality of lower branches (321), and the upper branches (312) and the lower branches (321) are distributed in a staggered manner.

2. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 1, wherein: the width of the slot (311) is larger than that of the bias line (130).

3. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 2, wherein: the central conductor (10) is directly connected with the first conduction band (111) of the left coplanar waveguide and the second conduction band (121) of the right coplanar waveguide or is connected with the width gradually changed.

4. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 3, wherein: the first ground plate (112) of the left coplanar waveguide is gradually away from the central conductor (10) in an exponential or linear distribution.

5. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 4, wherein: the distance or the length of the upper branch (312) and the lower branch (321) is gradually changed at the position close to the left coplanar waveguide (11) and the right coplanar waveguide (12).

6. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 5, wherein: when the upper conductor layer (14) and the lower conductor layer (30) are overlapped, the central conductor (10) is partially overlapped with the upper branch sections (312) and the lower branch sections (321) respectively.

7. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 6, wherein: the central conductor (10) is partially overlapped with the orthographic projections of the upper branch sections (312) and the lower branch sections (321) on the lower conductor layer (30).

8. The stub-loaded fast response electrically tuned liquid crystal phase shifter of claim 7, wherein: the upper branch knot (312) and the lower branch knot (321) are rectangular, triangular, trapezoidal or any other polygon, and the upper branch knot (312) and the lower branch knot (321) are the same or different in shape but cannot be connected.

Technical Field

The invention relates to the field of phase shifters, in particular to a quick response type electrically tuned liquid crystal phase shifter with branch loading.

Background

With the development of modern wireless communication systems, phase shifters are used as important components of phased array antennas, and are rapidly developing in the directions of miniaturization, low cost, low loss, high integration and the like.

Liquid crystal materials are widely used in phase shifter and antenna array design due to their advantages of electrically adjustable dielectric properties and low price. Compared with switch-type phase shifters such as MEMS and PIN diodes, liquid crystal phase shifters generally have the advantages of low cost, continuously adjustable phase, and easy integration. Therefore, designing a high performance liquid crystal phase shifter is becoming one of the hot spots in recent years.

The response time of the liquid crystal phase shifter is proportional to the square of the liquid crystal thickness, so in general, the liquid crystal thickness (distance between electrodes) below 5um is an important guarantee for the liquid crystal phase shifter to realize the millisecond-level fast response. At present, the reported fast response liquid crystal phase shifter is mainly implemented by a Load Line (Load Line), and can be classified into: coplanar waveguide (CPW) type phase shifters, microstrip line type phase shifters, and the like.

The existing solutions of the CPW phase shifter mainly include two types: (1) loading a metal bridge above the CPW, connecting the metal bridge with the ground plates on two sides of the CPW through a metal through hole, and respectively applying different voltages to the central conductor and the ground plates on two sides of the CPW after filling liquid crystal between the CPW and the upper layer metal bridge to obtain continuously adjustable phase shift; (2) loading a suspension electrode structure above the CPW, filling liquid crystal between the CPW and the suspension electrode, connecting a CPW central conductor and two side grounding plates through an Indium Tin Oxide (ITO) metal wire with the line width of 10um, and providing bias voltage for the upper suspension electrode and the lower CPW by using bias wires with the same line width so as to prepare an electrically adjustable phase shifter; although the above schemes can achieve a quality factor (FoM) of about 60 DEG/dB, the difficulty of implementing metal through holes in liquid crystal is high, and mass production cannot be achieved; in addition, the ITO metal line with the line width of 10um is easy to break, so that the yield of the phase shifter is greatly reduced, and the signal leakage is easily caused by the bias introduction mode.

In addition, the microstrip line type phase shifter ensures the stable transmission of electromagnetic waves by adopting a tail end coupling mode, and can realize FoM of about 30 degrees/dB; however, in addition to the bias line for receiving the applied dc voltage, the structure needs to additionally introduce a bias line to connect the metal conductors on the same layer; in order to reduce metal loss, a bias line for connecting metal conductors on the same layer can only be arranged on the outer side of the phase shifting structure, so that the physical size of the phase shifter is greatly increased, and the miniaturization of the structure cannot be realized. Meanwhile, the relatively low FoM of the phase shifter cannot meet the design goal of low loss of the communication system. Therefore, the liquid crystal phase shifter with high quality factor, miniaturization and easy processing has important practical application value.

Disclosure of Invention

The invention provides a quick response type electrically tuned liquid crystal phase shifter with branch loading in order to solve the existing problems, and aims to realize a miniaturized electrically tuned liquid crystal phase shifter which has high quality factor, high bias line impedance and easy processing without using a metal through hole and an ITO narrow bias line.

The invention relates to a quick response type electrically tuned liquid crystal phase shifter with branch loading, which comprises a first medium base material, a liquid crystal base material and a second medium base material, wherein the first medium base material, the liquid crystal base material and the second medium base material are sequentially stacked together.

The lower surface of the first dielectric substrate is provided with an upper conductor layer, and the upper conductor layer comprises a central conductor, a left coplanar waveguide, a right coplanar waveguide, a feed pad and a bias line;

the left coplanar waveguide consists of a first conduction band and a first grounding plate which is symmetrically arranged at two sides of the first conduction band by taking the first conduction band as a center;

the right coplanar waveguide consists of a second conduction band and a second grounding plate which is symmetrically arranged at two sides of the second conduction band by taking the second conduction band as a center;

the central conductor is positioned between the left coplanar waveguide and the right coplanar waveguide and is connected with a first conduction band of the left coplanar waveguide and a second conduction band of the right coplanar waveguide;

the feed pad is positioned at the lower edge of the right side of the first dielectric substrate and is connected with the central conductor through a bias line; the left coplanar waveguide and the right coplanar waveguide have the same structure, and the first ground plate of the left coplanar waveguide is gradually opened, so that the gap between the first ground plate of the left coplanar waveguide and the first conduction band of the left coplanar waveguide is gradually enlarged, and the smooth transition of impedance is ensured.

A lower conductor layer is arranged on the upper surface of the second dielectric substrate and comprises a first grounding plate and a second grounding plate, and a gap is formed between the first grounding plate and the second grounding plate and is not connected with the first grounding plate; etching a slot on the first grounding plate along the vertical projection of the bias line, and arranging a plurality of first grounding equipotential lines along the slot and crossing the slot; a second grounding equipotential line is arranged at a position which crosses the gap and is close to the slot, and the second grounding equipotential line is connected with the first grounding plate and the second grounding plate;

the edge of the first ground plate close to the gap is provided with a plurality of upper branches, the edge of the second ground plate close to the gap is provided with a plurality of lower branches, and the upper branches and the lower branches are distributed in a staggered mode.

The width of the slot is larger than that of the bias line, so that the impedance value of a transmission line formed by the bias line and the conductor layer is increased, and radio-frequency signals in the central conductor are prevented from entering the bias line.

The central conductor can be directly connected with the first conduction band of the left coplanar waveguide and the second conduction band of the right coplanar waveguide, and can also be connected with the left coplanar waveguide and the right coplanar waveguide in a gradually-changed manner.

The first ground plate of the left coplanar waveguide is gradually far away from the central conductor in an exponential distribution or a linear distribution.

And the upper branch and the lower branch ensure the impedance matching of the phase shifter in a mode of gradually changing the distance or the length at the positions close to the left coplanar waveguide and the right coplanar waveguide.

When the upper conductor layer is laminated with the lower conductor layer, the central conductor is partially overlapped with the upper branch knot and the lower branch knot respectively.

The central conductor is partially overlapped with the orthographic projections of the upper branch knot and the lower branch knot on the lower conductor layer.

The upper branch knot and the lower branch knot are in a rectangular shape, a triangular shape, a trapezoidal shape or any other polygonal shape, and the upper branch knot and the lower branch knot are in the same or different shapes but cannot be connected with each other.

The fast response type electric tuning liquid crystal phase shifter with branch loading adopts a CPW port to feed, and realizes impedance matching transition between the CPW and the coplanar waveguide (OCPW) by gradually opening a CPW flaring ground and alternate branches with gradually changed length or gradually changed distance; because the thickness of the liquid crystal substrate can be as thin as several microns, when an external direct current voltage acts on the central conductor and the grounding plates on two sides of the OCPW through the bias lines, the central conductor and the upper and lower overlapped parts of the branch sections, the dielectric constant of the liquid crystal changes within the time of millisecond magnitude, so that the phase of electromagnetic wave transmission is changed rapidly, and differential phase shift is generated. In addition, in order to prevent electromagnetic wave signals from entering the bias line to cause signal leakage, reduce the line width of the bias line and increase the width of a slot below the orthographic projection of the bias line, the method can be used for improving the impedance value of a transmission line formed by the bias line and a conductor layer, and the composite method can reduce the requirement on the over-narrow line width of the bias line, thereby improving the process stability.

The branches are loaded in a staggered manner, the structural layout is reasonable, and the electromagnetic wave can be more easily transmitted, so that the loss of the phase shifter is low, and the quality factor is high; a plurality of grounding equipotential lines are arranged in the phase shifter to ensure that the same layer electrode potentials are equal, the whole size is not increased, and the structure is easy to miniaturize.

Compared with the prior art, the invention has the beneficial effects that:

therefore, the liquid crystal phase shifter has the characteristics of high quality factor, high bias line impedance, easiness in realization of the process, mass production, low loss, convenience in miniaturization, array integration and the like.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention;

FIG. 2 is a schematic view of a conductive layer structure on a lower surface of a first dielectric substrate according to the present invention;

FIG. 3 is a schematic view of a conductive layer structure on the upper surface of a second dielectric substrate according to the present invention;

FIG. 4 is a schematic diagram of the lamination of upper and lower conductor layers according to the present invention;

FIG. 5 is a graph showing the results of experimental simulation of the reflection coefficient (S11) of the liquid crystal phase shifter according to the present invention;

FIG. 6 is a graph showing the experimental simulation results of the transmission coefficient (S21) of the liquid crystal phase shifter according to the present invention;

FIG. 7 is a graph showing the phase shift angle and FoM of the liquid crystal phase shifter according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

As shown in fig. 1-4, the invention discloses a fast response electrically tuned liquid crystal phase shifter with branch loading, which comprises a first dielectric substrate 1, a liquid crystal substrate 2 and a second dielectric substrate 3;

the lower surface of the first dielectric substrate 1 is provided with an upper conductor layer 14, and the upper conductor layer 14 comprises a central conductor 10, a left coplanar waveguide 11, a right coplanar waveguide 12, a feed pad 13 and a bias line 130;

the left coplanar waveguide 11 is composed of a first conduction band 111 and a first ground plate 112 symmetrically arranged on both sides of the first conduction band 111 with the first conduction band 111 as the center;

the right coplanar waveguide 12 is composed of a second conducting strip 121 and a second ground plate 122 symmetrically arranged on both sides of the second conducting strip 121 with the second conducting strip 121 as the center;

a central conductor 10 is located between said left coplanar waveguide 11 and said right coplanar waveguide 12 and is connected to a first conduction band 111 of said left coplanar waveguide 11 and to a second conduction band 121 of said right coplanar waveguide 12;

the feeding pad 13 is positioned at the lower edge of the right side of the first dielectric substrate 1 and is connected with the central conductor 10 through a bias line 130; the left coplanar waveguide 11 and the right coplanar waveguide 12 have the same structure, and the first ground plate 112 of the left coplanar waveguide 11 is gradually opened, so that the gap between the first ground plate 112 of the left coplanar waveguide and the first conduction band 111 of the left coplanar waveguide is gradually enlarged to ensure the smooth transition of impedance; similarly, the second ground plate 122 of the right coplanar waveguide 12 is gradually opened, so that a gap between the second ground plate 122 of the right coplanar waveguide 12 and the second conduction band 121 of the right coplanar waveguide 12 is gradually enlarged to ensure smooth transition of impedance;

a lower conductor layer 30 is arranged on the upper surface of the second dielectric substrate 3, the lower conductor layer 30 comprises a first grounding plate 31 and a second grounding plate 32, and a gap 33 is formed between the first grounding plate 31 and the second grounding plate 32 and is not connected with the first grounding plate 31 and the second grounding plate 32; the first grounding plate 31 is etched with a slot 311 along the vertical projection of the bias line, a plurality of first grounding equipotential lines 34 are arranged along the slot 311 and cross over the slot 311, so as to keep the potentials of the first grounding plate 31 at the two sides of the slot 311 equal and suppress the unwanted mode;

a second ground equipotential line 35 is disposed in the gap 33, across the gap 33 and near the slot 311, and the second ground equipotential line 34 is connected to the first ground plane 31 and the second ground plane 32 for keeping the potentials of the first ground plane 31 and the second ground plane 32 equal;

the first ground plate 31 has a plurality of upper branches 312 near the edge of the slot 33 and facing the slot, the second ground plate 32 has a plurality of lower branches 321 near the edge of the slot 33 and facing the slot, and the upper branches 312 and the lower branches 321 are distributed in a staggered manner.

Three dielectric substrates, namely a first dielectric substrate 1, a liquid crystal substrate 2 and a second dielectric substrate 3, are sequentially stacked from top to bottom.

The width of the slot 311 is larger than the width of the bias line 130, so that the impedance of the transmission line formed by the bias line 130 and the lower conductor layer 30 is increased, and the rf signal in the central conductor 10 is prevented from entering the bias line 130.

The central conductor 10 may be directly connected to the first conduction band of the left coplanar waveguide and the second conduction band of the right coplanar waveguide, or may be connected to each other with a gradually changing width.

The first ground plate 112 of the left coplanar waveguide may be exponentially or linearly distributed gradually away from the center conductor 10.

The upper branches 312 and the lower branches 321 have a certain amount of overlap with the orthographic projection of the central conductor 10 on the lower conductor layer 30.

The upper branch and the lower branch are close to the left coplanar waveguide and the right coplanar waveguide and ensure the impedance matching of the phase shifter in a gradual change mode;

the method specifically comprises the following steps: at the position close to the left coplanar waveguide 11, the lengths of the upper branch 312 and the lower branch 321 gradually increase from left to right, or the distance between the upper branch 312 and the lower branch 321 gradually decreases from left to right; near the right coplanar waveguide 12, the lengths of the upper branch 312 and the lower branch 321 gradually increase from right to left, or the distance between the upper branch 312 and the lower branch 321 gradually decreases from right to left, so as to ensure the impedance matching of the phase shifter.

The upper branch node 312 and the lower branch node 321 may be rectangular, triangular, trapezoidal or any other polygon, and the upper branch node 312 and the lower branch node 321 may have different shapes but cannot be connected; when the branch knots are different in shape, the design flexibility is enhanced, and the performance is improved to a certain degree.

The width of the gap 33 may be smaller than the width of the central conductor 10, depending on the thickness of the liquid crystal layer and its dielectric constant, when the impedance requirements of the system to the phase shifter are low.

The distance between upper branch node 312 and lower branch node 321 may be periodic or aperiodic.

The central conductor 10 is at the part where the vertical projection with the upper branch 312 and the lower branch 321 overlaps, and the line width of the central conductor 10 may be wider than the non-overlapping part; the central conductor 10 may be directly connected to the non-overlapping portion or may be connected to the non-overlapping portion at the portion overlapping with the vertical projection of the upper branch 312 and the lower branch 321.

The phase shift portion (the portion formed by the central conductor 10 and the first ground plate 31 and the second ground plate 32 of the loading stub) based on the OCPW may be any other shape based on the linear shape, such as a straight shape, a bent shape, and a spiral shape.

The fast response type electric tuning liquid crystal phase shifter loaded with the branch adopts a CPW port for feeding, and realizes impedance matching transition between the CPW and the OCPW by gradually opening a CPW flaring ground and alternate branches with gradually changed lengths or gradually changed distances; because the thickness of the liquid crystal substrate can be as thin as several microns, when an external direct current voltage acts on the central conductor and the grounding plates on two sides of the OCPW through the bias lines, the central conductor and the upper and lower overlapped parts of the branch sections, the dielectric constant of the liquid crystal changes within the time of millisecond magnitude, so that the phase of electromagnetic wave transmission is changed rapidly, and differential phase shift is generated.

In addition, in order to prevent electromagnetic wave signals from entering the bias line to cause signal leakage, the line width of the bias line is reduced, the slot width below the orthographic projection of the bias line is increased, and the impedance value of a transmission line formed by the bias line and the conductor layer is improved; the composite method can reduce the requirement on the over-narrow line width of the bias line, thereby improving the process stability.

The branches are loaded in a staggered manner, the structural layout is reasonable, and the electromagnetic wave can be more easily transmitted, so that the loss of the phase shifter is low, and the quality factor is high; a plurality of grounding equipotential lines are arranged in the phase shifter to ensure that the same layer electrode potentials are equal, the whole size is not increased, and the structure is easy to miniaturize.

The metal material in the invention is selected to be copper, the thickness of the copper is 0.005mm, and in order to prevent the copper exposed in the air from being oxidized, a layer of gold with the thickness of about 0.02um is generally required to be plated on the copper.

The first dielectric substrate 1 and the second dielectric substrate 3 are borosilicate glass with dielectric constant as related electrical parameterε _r=4.6, loss tangent tanδAnd 0.01, wherein the thicknesses of the first dielectric substrate 1 and the second dielectric substrate 3 are both 0.5 mm.

The relative electric parameter of the liquid crystal substrate 2 is that the variation range of the dielectric constant is more than or equal to 2.7ε _rNot more than 3.8, and tan of loss tangent variation range of 0.0121 not more thanδLess than or equal to 0.0050 and 4um thick.

In actual processing, a frame is arranged between the first medium substrate 1 and the second medium substrate 3 and around the liquid crystal substrate 2, and a crystal filling opening is reserved; the frame is made of Epoxy resin (Epoxy) and the related electrical parameter is dielectric constantε _r=3.82, loss tangent tanδAnd (5) the coefficient of expansion is about 2.6-3 and the coefficient of expansion is 0.01.

In addition, in order to improve the alignment capability of the liquid crystal molecules, it is generally required to cover a layer of Polyimide (PI) with a thickness of about 0.01um above the lower conductor layer 30 and rub it to generate grooves, so that the liquid crystal molecules are orderly arranged along the grooves.

Fig. 5 and 6 are S-parameter diagrams of the phase shifter:

as can be seen from FIG. 5, when the dielectric constant is changed, the reflection coefficient is kept below-13 dB in the range of 12-16 GHz, which shows that the phase shifter has strong impedance matching capability and wide operating bandwidth.

As can be seen from fig. 6, the insertion loss of the phase shifter increases with an increase in the dielectric constant, but remains substantially above-4.5 dB, indicating that the loss of the phase shifter is low.

Fig. 7 shows the phase shift angle and FoM of the phase shifter, and it can be seen from fig. 7 that the phase shifter achieves a phase shift of more than 360 ° and a FoM of nearly 100 °/dB at 14.125 GHz.

While the invention has been described in terms of its preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.