Multifunctional device based on nematic liquid crystal

Abstract

The invention discloses a multifunctional device based on nematic liquid crystal, which comprises an FR4 substrate, a liquid crystal interlayer and an F4B bottom plate, the FR4 substrate, the liquid crystal interlayer and the F4B bottom plate are connected in sequence, the FR4 substrate comprises an FR4 medium and a filtering feed network, and the FR4 substrate is connected with the liquid crystal interlayer at the lower end; the liquid crystal interlayer comprises a glass box and nematic liquid crystals, the nematic liquid crystals are located in the glass box, the upper end of the glass box is connected with the lower end surface of the FR4 substrate, and the lower surface of the glass box is connected with the F4B bottom plate; the F4B bottom plate comprises a copper ground and an F4B medium, the copper ground is located on the upper surface of the F4B medium, and the copper ground is connected with the lower end surface of the glass box. According to the invention, through temperature regulation and control, frequency reconfiguration and phase shift functions are realized, and the device has the advantages of low manufacturing cost, simple integration and simple phase modulation.

Description

Technical Field

[0001] The invention relates to the technical field of communication systems and instruments and meters, and in particular to a multifunctional device based on nematic liquid crystal. Background Art

[0002] The demand for tunable materials is increasing due to the rapid development of engineering and materials science. Liquid crystals (LCs) are tunable materials with unique molecular configurations and superior operational properties, playing a key role in the fields of displays, optical lenses, and switches. In addition to their significant contributions to the field of optics, LCs are increasingly gaining interest in the field of electromagnetics to promote tunable devices, including phase shifters, absorbers, phased arrays, metasurfaces, and antennas.

[0003] Filters, as an important component of electronic devices, have the basic function of selecting or eliminating specific frequency bands. Therefore, the demand for devices capable of frequency reconstruction has increased the importance of frequency reconfigurable filters. Although conventional technologies have shown superior tunability, their deployment poses great challenges and incurs considerable expenditure. In contrast, liquid crystal technology is known for its compactness, low insertion loss, and cost-effectiveness. Therefore, researchers have also explored the application of liquid crystals in realizing tunable filters. However, the operation of conventional liquid crystal filters requires a driving voltage.

[0004] Adjustable phase shifters, which are widely used in contemporary communication systems, can be combined with liquid crystals. Liquid crystal phase shifters have potential applications in satellite communications due to their high reliability in harsh environments. However, the application of electric field modulation alone does not guarantee uniform rotation of LC molecules. The disadvantage of non-uniformity has an adverse effect on the efficacy of devices such as filters and phase shifters. In addition, the use of excessively high voltages not only increases the complexity of the project, but also poses potential safety hazards.

[0005] The prior art has studied voltage modulation of liquid crystal adjustable phase shifters, but there is no multifunctional device that can simultaneously realize filtering and phase shifting functions based on the temperature regulation principle. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention discloses a multifunctional device based on nematic liquid crystal to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a multifunctional device based on nematic liquid crystal, comprising a FR4 substrate, a liquid crystal interlayer and a F4B bottom plate, wherein the FR4 substrate, the liquid crystal interlayer and the F4B bottom plate are connected in sequence.

[0008] The FR4 substrate includes an FR4 medium and a filter feed network, and the FR4 substrate is connected to the liquid crystal interlayer at the lower end;

[0009] The liquid crystal interlayer includes a glass box and a nematic phase liquid crystal, the nematic phase liquid crystal is located in the glass box, the upper end of the glass box is connected to the lower end surface of the FR4 substrate, and the lower surface of the glass box is connected to the F4B bottom plate;

[0010] The F4B bottom plate includes a copper ground and an F4B medium, wherein the copper ground is located on the upper surface of the F4B medium and is connected to the lower end surface of the glass box.

[0011] Preferably, the dielectric constant of the FR4 medium is 4.4, the dielectric loss tangent is 0.02, the medium is 28 mm long, 10 mm wide, and 1.5 mm thick.

[0012] Preferably, the filter feed network is printed at the center of the lower surface of the FR4 substrate; and one side of the FR4 substrate containing the filter feed network is connected to the liquid crystal interlayer at the lower end.

[0013] Preferably, the filtering feeding network is realized by a parallel coupling line with a width of 0.16 mm, and the coupling line includes five parallel microstrip lines with lengths of 4.61 mm, 8.45 mm, and 8.26 mm, which are placed horizontally and crossed, and are spaced 0.1 mm and 0.23 mm apart in sequence.

[0014] Preferably, the glass box is 20 mm long, 20 mm wide and 0.6 mm thick; the nematic liquid crystal is encapsulated in an interlayer provided inside the glass box, model: HSG14100-200, the liquid crystal is 20 mm long, 12 mm wide and 0.2 mm thick; a copper patch port is provided in the middle of the nematic liquid crystal seal.

[0015] Preferably, when the initial temperature of the nematic phase liquid crystal is 40°C, in parallel orientation, the dielectric constant is 9.2628, the loss tangent is 0.0041, and in vertical orientation, the dielectric constant is 36.1667, and the loss tangent is 0.0036; when the temperature is raised to 120, in parallel orientation, the dielectric constant is 13.6051, the loss tangent is 0.0096, and in vertical orientation, the dielectric constant is 13.4101, and the loss tangent is 0.0437.

[0016] Preferably, the copper ground is printed on the upper surface of the F4B medium, and the side of the F4B medium containing the copper ground is connected to the lower surface of the glass box. The F4B medium has a dielectric constant of 2.2, a dielectric loss tangent of 0.001, a length of 20 mm, a width of 20 mm, and a thickness of 3 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention provides a multifunctional device based on nematic liquid crystal. At temperatures of 40°C, 80°C and 120°C, the passband bandwidths of the device prepared based on parallel-oriented liquid crystal are 7.19-9.73 GHz, 7.18-9.69 GHz and 7.09-9.56 GHz, respectively; the corresponding passband bandwidths of the multifunctional device prepared based on vertical-oriented liquid crystal are 6.87-9.19 GHz, 6.93-9.31 GHz and 7.09-9.57 GHz, respectively.

[0019] 2. The present invention provides a multifunctional device based on nematic phase liquid crystal. When the temperature rises from 40°C to 120°C, the phase shifts of the device based on parallel-oriented liquid crystal at 7.5GHz and 9GHz are 11.85 and 19.08 respectively; the multifunctional device based on vertical-oriented liquid crystal reaches 31.89 and 47.80 respectively. The multifunctional device realizes frequency reconfiguration and phase shifting functions through temperature control, and has the advantages of low manufacturing cost, simple integration, and simple phase modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0021] In the attached picture:

[0022] Figure 1 is a schematic diagram of the overall structure of a multifunctional device based on nematic liquid crystal according to an embodiment of the present invention;

[0023] Figure 2 1 is a schematic diagram of the back side of an FR4 substrate of a multifunctional device based on nematic liquid crystal according to an embodiment of the present invention (above) and a plan view of a feeding network (below);

[0024] Figure 3 is a schematic diagram of the dielectric constant (a) and the loss tangent (b) of the nematic liquid crystal material at different temperatures according to an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of S11 and S21 scattering parameters of a multifunctional device based on nematic liquid crystal at different temperatures according to an embodiment of the present invention;

[0026] Figure 5 is a phase change spectrum of a multifunctional device based on nematic liquid crystal at different temperatures according to an embodiment of the present invention;

[0027] Numbers in the figure: 1, FR4 substrate; 2, glass box; 3, liquid crystal; 4, copper patch port; 5, copper ground; 6, F4B medium; 7, filter feeding network. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0029] Example: Figure 1 and Figure 2 As shown, a multifunctional device based on nematic liquid crystal includes a FR4 substrate 1, a liquid crystal 3 interlayer and a F4B bottom plate, wherein the FR4 substrate 1, the liquid crystal 3 interlayer and the F4B bottom plate are connected in sequence, wherein the FR4 substrate 1 includes a FR4 medium and a filter feed network 7, wherein the filter feed network 7 is printed at the center of the lower surface of the FR4 substrate 1; wherein the filter feed network 7 is implemented by a parallel coupling line, wherein the coupling line includes five parallel microstrip lines that are horizontally placed and spaced in pairs; wherein the FR4 substrate 1 includes a side of the filter feed network 7 connected to the liquid crystal 3 interlayer at the lower end; wherein the liquid crystal 3 interlayer includes a glass box 2 and a nematic liquid crystal 3, the nematic liquid crystal 3 is located in the glass box 2, the nematic liquid crystal 3 is encapsulated in an interlayer provided inside the glass box 2, a copper patch port 4 is provided in the middle of the seal of the nematic liquid crystal 3, the upper end of the glass box 2 is connected to the lower end surface of the FR4 substrate 1, and the lower surface of the glass box 2 is connected to the F4B bottom plate; the F4B bottom plate includes a copper ground 5 and a F4B medium 6, the copper ground 5 is located on the upper surface of the F4B medium 6, the copper ground 5 is printed on the upper surface of the F4B medium 6, and the side of the F4B medium 6 containing the copper ground 5 is connected to the lower surface of the glass box 2.

[0030] In the present invention, the ability of the liquid crystal material to change its dielectric anisotropy is utilized to achieve frequency reconfiguration and phase shifting functions through temperature regulation, which has several advantages such as low manufacturing cost, simple integration, and simple phase modulation.

[0031] The overall structure diagram of the multifunctional device is shown in Figure 1As shown, the FR4 substrate, the liquid crystal interlayer, and the F4B bottom plate are connected in sequence. The FR4 substrate includes a FR4 medium and a filter feed network 7 printed on the lower surface, which is connected to the glass box 2. The dielectric constant of the FR4 medium is 4.4, the dielectric loss tangent is 0.02, the medium length l2 is 28mm, the width l1 is 10mm, and the thickness h1 is 1.5mm. The liquid crystal 3 is encapsulated in the glass box 2, the model is: HSG14100-200, the liquid crystal length l4 is 20mm, the width is 12mm, and the thickness h3 is 0.2mm. The lower surface of the glass box 2 is connected to the copper ground 5, the glass box length l4 is 20mm, the width l3 is 20mm, and the thickness h2 is 0.6mm. The copper ground 5 is connected to the F4B medium 6, the dielectric constant of the F4B medium is 2.2, the dielectric loss tangent is 0.001, the length l4 is 20mm, the width l3 is 20mm, and the thickness h4 is 3mm. There is a copper patch port 4 at the sealing portion of the liquid crystal 3 .

[0032] The schematic diagram of the back side of the FR4 substrate (above) and the plan view of the feed network 7 (below) are as follows Figure 2 As shown, the feed network 7 is printed at the center of the back of the FR4 substrate. The filter feed network 7 is printed at the center of the lower surface of the substrate, and is realized by a parallel coupling line with a width w2 of 0.16 mm. The coupling line is composed of five parallel microstrip lines with lengths of d1 = 4.61 mm, d2 = 8.45 mm, and d3 = 8.26 mm, which are placed horizontally and spaced s1 = 0.1 mm and s2 = 0.23 mm in sequence.

[0033] like Figure 1 and Figure 2 As shown, the design parameters of the multifunctional device and its feeding network 7 are shown in Table 1.

[0034] parameter <![CDATA[h1]]> <![CDATA[h2]]> <![CDATA[h3]]> <![CDATA[h4]]> <![CDATA[l1]]> <![CDATA[l2]]> <![CDATA[l3]]> <![CDATA[l4]]> Value(mm) 1.5 0.2 0.6 3 10 28 20 20 parameter <![CDATA[l5]]> <![CDATA[w1]]> <![CDATA[w2]]> <![CDATA[d1]]> <![CDATA[d2]]> <![CDATA[d3]]> <![CDATA[s1]]> <![CDATA[s2]]> Value(mm) 4 0.88 0.16 4.61 8.45 8.26 0.1 0.23

[0035] like Figure 3 As shown, when the initial temperature of the nematic phase liquid crystal is 40°C, in parallel orientation, the dielectric constant is 9.2628, the loss tangent is 0.0041, and in vertical orientation, the dielectric constant is 36.1667, and the loss tangent is 0.0036; when the temperature is increased to 120, in parallel orientation, the dielectric constant is 13.6051, the loss tangent is 0.0096, and in vertical orientation, the dielectric constant is 13.4101, and the loss tangent is 0.0437.

[0036] like Figure 4 As shown in (a), at temperatures of 40°C, 80°C and 120°C, the corresponding dielectric constants are 9.2628, 10.0418 and 13.6051, respectively, and the passband bandwidths are 7.19-9.73 GHz, 7.18-9.69 GHz and 7.09-9.56 GHz, respectively. Figure 4(b) shows that the insertion loss values ​​within the operating frequency band are all above -1.82dB. Figure 4 (c) It can be seen that the dielectric constants are 37.1667, 27.0587 and 13.4101, respectively, and the corresponding passband bandwidths are 6.87~9.19GHz, 6.93~9.31GHz and 7.09~9.57GHz, respectively. Figure 4 (d) The insertion loss values ​​within the operating frequency band are all above -2.10dB.

[0037] like Figure 5 As shown in (a), when the temperature increases from 40°C to 120°C, the phase shifts of the device based on parallel-oriented liquid crystal at 7.5 GHz and 9 GHz are 11.85 and 19.08, respectively; the phase shifts of the multifunctional device based on vertical-oriented liquid crystal reach 31.89 and 47.80, respectively.

[0038] Finally, after a specific design including integrated filter phase shifters and nematic liquid crystals, the dielectric constant changed more significantly between 40°C and 120°C as the temperature rose from 40°C to 120°C, and the multifunctional device achieved more obvious frequency modulation and phase shift.

[0039] This multifunctional device achieves frequency reconfiguration and phase shifting functions through temperature control, and also has the advantages of low manufacturing cost, simple integration, and simple phase modulation.

[0040] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multifunctional device based on nematic liquid crystal, characterized in that: It includes a FR4 substrate, a liquid crystal interlayer and a F4B bottom plate, wherein the FR4 substrate, the liquid crystal interlayer and the F4B bottom plate are connected in sequence. The FR4 substrate includes an FR4 medium and a filter feed network, and the FR4 substrate is connected to the liquid crystal interlayer at the lower end; The liquid crystal interlayer includes a glass box and a nematic phase liquid crystal, the nematic phase liquid crystal is located in the glass box, the upper end of the glass box is connected to the lower end surface of the FR4 substrate, and the lower surface of the glass box is connected to the F4B bottom plate; The F4B bottom plate includes a copper ground and an F4B medium, wherein the copper ground is located on the upper surface of the F4B medium and is connected to the lower end surface of the glass box.

2. A multifunctional device based on nematic liquid crystal according to claim 1, characterized in that: The dielectric constant of the FR4 medium is 4.4, and the dielectric loss tangent is 0.

02.

3. A multifunctional device based on nematic liquid crystal according to claim 1, characterized in that: The filter feed network is printed at the center of the lower surface of the FR4 substrate; one side of the FR4 substrate containing the filter feed network is connected to the liquid crystal interlayer at the lower end.

4. A multifunctional device based on nematic liquid crystal according to claim 3, characterized in that: The filtering and feeding network is realized by a parallel coupling line, and the coupling line includes five parallel microstrip lines which are arranged horizontally and crossed and spaced in pairs.

5. The multifunctional device based on nematic liquid crystal according to claim 1, characterized in that: The nematic liquid crystal is encapsulated in an interlayer provided inside the glass box, and a copper patch port is provided in the middle of the sealing portion of the nematic liquid crystal.

6. A multifunctional device based on nematic liquid crystal according to claim 5, characterized in that: When the initial temperature of the nematic phase liquid crystal is 40°C, in parallel orientation, the dielectric constant is 9.2628 and the loss tangent is 0.0041, while in vertical orientation, the dielectric constant is 36.1667 and the loss tangent is 0.0036; when the temperature is raised to 120°C, in parallel orientation, the dielectric constant is 13.6051 and the loss tangent is 0.0096, while in vertical orientation, the dielectric constant is 13.4101 and the loss tangent is 0.0437.

7. The multifunctional device based on nematic liquid crystal according to claim 1, characterized in that: The copper ground is printed on the upper surface of the F4B medium, and the side of the F4B medium containing the copper ground is connected to the lower surface of the glass box. The dielectric constant of the F4B medium is 2.2, and the dielectric loss tangent is 0.001.

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