Power distribution networks, liquid crystal antennas, and communication equipment

Abstract

Embodiments of the present invention provide a power distribution network, a liquid crystal antenna including the power distribution network, and a communication device including the liquid crystal antenna. The power distribution network is configured for use in the liquid crystal antenna and includes multiple cascaded power dividers. Each power divider includes a first microstrip line, a transmission medium region, and a reference electrode, wherein the tangent of the dielectric loss angle of the transmission medium in the transmission medium region is smaller than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal antenna.

Description

Technical Field

[0001] This invention generally relates to the field of communication technology. More specifically, this invention relates to a power distribution network, a liquid crystal antenna including the power distribution network, and a communication device employing the liquid crystal antenna. Background Technology

[0002] In a typical liquid crystal array antenna system, the power distribution network distributes the input power evenly to multiple output ports through a cascaded one-to-two power divider. The power distribution network is typically required to feed the array elements without disrupting or minimally affecting the continuity of other structures. Power dividers can be classified into microstrip power dividers and cavity power dividers based on their structure. Microstrip power dividers are commonly used in liquid crystal array antennas. Compared to cavity power dividers, microstrip power dividers offer higher isolation and integration, but suffer from higher insertion loss. Therefore, there is a need in this field for a low-loss power distribution network suitable for high-efficiency liquid crystal antennas. Summary of the Invention

[0003] In view of this, one aspect of the present invention provides a power distribution network configured for use in a liquid crystal antenna, and includes: a plurality of cascaded power dividers, each power divider including a first microstrip line, a transmission medium region, and a reference electrode, wherein the tangent of the dielectric loss angle of the transmission medium in the transmission medium region is less than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal antenna.

[0004] According to some embodiments of the present invention, the first microstrip line includes a plurality of microstrip lines with different impedances, and each power divider further includes a first impedance transformer electrically coupled between the first microstrip lines with different impedances.

[0005] According to some embodiments of the present invention, the transmission medium in the transmission medium region is air.

[0006] According to some embodiments of the present invention, the width of the first microstrip line satisfies the following formula: in, This represents the characteristic impedance of the first microstrip line. This represents the effective dielectric constant of the transmission medium in the transmission medium region. This represents the permeability of the transmission medium in the transmission medium region. Indicates the width of the first microstrip line. This indicates the thickness of the transmission medium region.

[0007] Another aspect of the present invention provides a liquid crystal antenna. The liquid crystal antenna includes a first substrate and a second substrate disposed opposite to each other; a plurality of radiating elements disposed on a side of the first substrate away from the second substrate; any of the aforementioned power distribution networks configured to feed electromagnetic signals to the plurality of radiating elements; and a phase shifter. The phase shifter includes: a plurality of liquid crystal regions disposed between the first substrate and the second substrate; a reference electrode disposed between the first substrate and the plurality of liquid crystal regions; and a second microstrip line disposed between the second substrate and the plurality of liquid crystal regions. The plurality of liquid crystal regions correspond one-to-one with the plurality of radiating elements, and each radiating element and the orthographic projection of the corresponding liquid crystal region on the second substrate at least partially overlap. The transmission medium region of each power divider is disposed between adjacent liquid crystal regions, the reference electrode of each power divider is disposed between the first substrate and the transmission medium region, and the first microstrip line of each power divider is disposed between the second substrate and the transmission medium region. The tangent of the dielectric loss angle of the transmission medium in the transmission medium region of each power divider is less than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal region.

[0008] According to some embodiments of the present invention, the transmission medium region and the adjacent liquid crystal region are separated by a barrier.

[0009] According to some embodiments of the present invention, the retaining wall is made of sealing adhesive.

[0010] According to some embodiments of the present invention, the liquid crystal antenna further includes a second impedance transformer electrically coupled between adjacent first and second microstrip lines.

[0011] According to some embodiments of the present invention, the width of the second microstrip line satisfies the following formula: in, This represents the characteristic impedance of the second microstrip line. This represents the effective dielectric constant of the liquid crystal in the liquid crystal region. This represents the permeability of the liquid crystal in the liquid crystal region. Indicates the width of the first microstrip line. This indicates the thickness of the liquid crystal region.

[0012] Another aspect of the present invention provides a communication device that employs any of the aforementioned liquid crystal antennas.

[0013] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention in any way. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. It should be noted that the dimensions shown in the drawings are merely schematic and are not intended to limit the present invention in any way.

[0015] Figure 1 A schematic top view of a conventional liquid crystal antenna is shown.

[0016] Figure 2 A top view schematically illustrating a liquid crystal antenna including a power distribution network according to an embodiment of the present invention is shown.

[0017] Figure 3 The schematic diagram illustrates the following along Figure 2 A cross-sectional view of the liquid crystal antenna along the A-A' direction.

[0018] Figure 4 The schematic diagram illustrates the following along Figure 2 A cross-sectional view of the liquid crystal antenna in the B-B' direction.

[0019] Figure 5 The simulation results of the transmission loss of microstrip lines in liquid crystal are shown.

[0020] Figure 6 The simulation results show the transmission loss of microstrip lines in air.

[0021] The accompanying drawings illustrate specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Figure 1 A schematic top view of a conventional liquid crystal antenna is shown. (As...) Figure 1 As shown, the liquid crystal antenna 100 includes a plurality of radiating elements 101, a power distribution network, and a phase shifter. The power distribution network includes a plurality of cascaded power dividers 104, each power divider 104 including microstrip lines 105, 105', and a corresponding portion of a liquid crystal region 103 enclosed by a sealing adhesive 102. The power distribution network is configured to feed electromagnetic signals to each of the radiating elements 101.

[0024] In an exemplary embodiment, further, to prevent energy loss during transmission, when the power divider 104 includes microstrip lines 105 and 105' with different impedances, such as Figure 1 As shown, the power divider 104 also includes an impedance transformer 106 electrically coupled between microstrip lines 105 and 105' with different impedances in order to match the characteristic impedances of microstrip lines 105 and 105'.

[0025] In addition, as those skilled in the art will understand, the liquid crystal antenna 100 should also include other components that enable it to function properly, such as a reference electrode that forms an electric field with the microstrip lines 105, 105' to adjust the orientation of liquid crystal molecules, and a controller that provides a low-frequency voltage signal to the microstrip lines 105, 105' to control the orientation of liquid crystal molecules accordingly.

[0026] In such Figure 1 In the liquid crystal antenna 100 shown, the reference electrode, microstrip line 107, and liquid crystal region 103 function as a phase shifter. In the liquid crystal antenna 100, a power distribution network feeds electromagnetic signals of equal amplitude and in phase to each radiating element 101. The phase shifter changes the phase of the fed electromagnetic signal by altering the dielectric constant of the liquid crystal, and the phase-changed electromagnetic signal is transmitted through the radiating element 101. By applying different voltages to the liquid crystal molecules corresponding to each radiating element 101 via the microstrip line 107 and the reference electrode, the liquid crystal molecules will deflect to different degrees, thereby causing different phase changes in the fed electromagnetic signal.

[0027] However, the inventors of this invention recognize that, in situations such as Figure 1 In the liquid crystal antenna shown, phase shifting is achieved through the liquid crystal, therefore, electromagnetic signal loss in the liquid crystal is unavoidable. However, the power divider is only used for transmitting electromagnetic signals with equal amplitude and in phase, and does not require phase shifting. Therefore, in situations such as... Figure 1 In the liquid crystal antenna 100 shown, using liquid crystal, which has a large transmission loss, as the transmission medium increases the transmission medium loss of the liquid crystal antenna.

[0028] In view of this, embodiments of the present invention provide a power distribution network. Figure 2 A schematic top view of a liquid crystal antenna 200 including a power distribution network according to an embodiment of the present invention is shown. Figure 3 The schematic diagram illustrates the following along Figure 2 A cross-sectional view of the liquid crystal antenna 200 in the A-A' direction, and Figure 4 The schematic diagram illustrates the following along Figure 2 A cross-sectional view of the liquid crystal antenna 200 in the B-B' direction. (See figure.) Figures 2-4As shown, the liquid crystal antenna 200 includes a first substrate 201 and a second substrate 202 disposed opposite to each other. A plurality of radiating elements 203 are disposed on the side of the first substrate 201 away from the second substrate 202. The liquid crystal antenna 200 includes a power distribution network configured to feed electromagnetic signals to the plurality of radiating elements 203. The power distribution network includes a plurality of cascaded power dividers 205. Each power divider 205 includes a transmission medium region 208, a first microstrip line 211 disposed between the second substrate 202 and the transmission medium region 208, and a reference electrode 206 disposed between the first substrate 201 and the transmission medium region 208. Figure 2 As shown, the transmission medium regions 208 of the plurality of power dividers 205 are continuous with each other. Further, the liquid crystal antenna 200 includes a phase shifter. The phase shifter includes a plurality of liquid crystal regions 204 disposed between the first substrate 201 and the second substrate 202, a reference electrode 206 disposed between the first substrate 201 and the plurality of liquid crystal regions 204, and a second microstrip line 207 disposed between the second substrate 202 and the plurality of liquid crystal regions 204. The second microstrip line 207 is configured to cooperate with the reference electrode 206 to control the orientation of liquid crystal molecules in each liquid crystal region 204.

[0029] Specifically, each of the plurality of liquid crystal regions 204 corresponds one-to-one with the plurality of radiating elements 203, and the orthographic projection of each radiating element 203 and the corresponding liquid crystal region 204 on the second substrate 202 at least partially overlaps, and the transmission medium region 208 is disposed between adjacent liquid crystal regions 204, such as... Figure 3 and Figure 4 As shown. Moreover, the tangent of the dielectric loss angle of the transmission medium in the transmission medium region 208 of each power divider 205 is less than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal region 204.

[0030] It should be pointed out that, although Figure 2 The illustration schematically depicts a 2x2 liquid crystal array antenna, but the concept of the present invention is not limited to this, and can be applied to liquid crystal antennas comprising any number of array elements. Furthermore, the concept of the present invention is applicable not only to liquid crystal microstrip antennas, but also to transceiver-integrated liquid crystal phased array antennas.

[0031] In the above embodiments of the present invention, a liquid crystal region is provided in the area where the phase shifter function needs to be implemented to ensure the large-angle phase shifting function of the phase shifter. In other areas, the power distribution network uses a different transmission medium than the liquid crystal, which has a smaller dielectric loss angle than the liquid crystal. As used herein, the term "dielectric loss angle," also known as the dielectric phase angle, is the ratio of the amount of power distributed to the amount of power not distributed in the dielectric under AC voltage, and reflects the magnitude of energy loss per unit volume within the dielectric. Compared to... Figure 1The liquid crystal antenna 100 shown can significantly reduce the transmission loss generated by the liquid crystal in the power distribution network by replacing the transmission medium in the area other than the area where the phase shifter function needs to be implemented with a transmission medium with a smaller dielectric loss angle (i.e., less energy loss per unit volume) in the area where the liquid crystal antenna 200 is shown. This is achieved while ensuring that the input signal is evenly distributed to each array element with equal amplitude and phase.

[0032] In an exemplary embodiment, such as Figure 2 and Figure 4 As shown, the first microstrip line 211 includes multiple microstrip lines 211 and 211' with different impedances, and each power divider 205 also includes a first impedance transformer 209 electrically coupled between the first microstrip lines 211 and 211' with different impedances. When the load impedance and the characteristic impedance of the microstrip line are unequal, or when two microstrip lines with different characteristic impedances are connected, the transmitted signal will be reflected, resulting in transmission loss. Therefore, an impedance transformer can be used between the load requiring impedance matching and the microstrip line or between two microstrip lines to achieve impedance matching, thereby reducing transmission loss. Therefore, as used herein, the term "impedance transformer" can also be called an impedance matching device. Figure 2 In the 2x2 liquid crystal array antenna shown, the input signal is transmitted to each array element in equal amplitude and phase through a cascaded one-to-two power divider. At each branch point, a first impedance transformer 209 is set to achieve impedance matching of the power distribution network.

[0033] In some example embodiments, the transmission medium in the transmission medium region 208 is air. In other words, the transmission medium region 208 is filled with air. In this way, the manufacturing process of the liquid crystal antenna can be simplified and the manufacturing cost of the liquid crystal antenna can be reduced.

[0034] Optionally, such as Figure 2 As shown, the transmission medium region 208 and the adjacent liquid crystal region 204 can be separated by a barrier 210. In an exemplary embodiment, the barrier 210 can be made of sealing adhesive. For example, during the manufacturing process, different transmission medium regions inside the array antenna are isolated and distinguished by sealing adhesive, and liquid crystal is dripped into the region where the phase shifter function needs to be implemented, thereby ensuring the large-angle phase shifting function of the phase shifter.

[0035] In particular, in an exemplary embodiment, the width of the first microstrip line can satisfy the following formula: in, This represents the characteristic impedance of the first microstrip line. This represents the effective dielectric constant of the transmission medium in transmission medium region 208. This represents the permeability of the transmission medium in transmission medium region 208. Indicates the width of the first microstrip line. This indicates the thickness of the transmission medium region 208.

[0036] Similarly, in an exemplary embodiment, the width of the second microstrip line 207 can satisfy the following formula: in, This represents the characteristic impedance of the second microstrip line 207. This represents the effective dielectric constant of the liquid crystal in liquid crystal region 204. This represents the permeability of the liquid crystal in liquid crystal region 204. This indicates the width of the second microstrip line 207. This indicates the thickness of the liquid crystal region 204.

[0037] In an exemplary embodiment, such as Figure 3 and 4 As shown, the liquid crystal antenna 200 may optionally include a first alignment layer 212 located between the liquid crystal region 204 and the second substrate 202, and a second alignment layer 213 located between the liquid crystal region 204 and the first substrate 201. The first alignment layer 212 and the second alignment layer 213 cooperate with each other to set the initial alignment of the liquid crystal region 204.

[0038] Figure 5 and Figure 6 Simulation results of transmission loss for microstrip lines using liquid crystal and air as the transmission medium are shown respectively. Since power distribution networks are mainly composed of microstrip lines, the main difference between different power distribution networks lies in the length of the microstrip lines. The transmission loss of a microstrip line is linearly related to its length. Therefore, the loss of a power distribution network including microstrip lines of different lengths can be inferred from the loss of a microstrip line of a fixed length. (Comparison) Figure 5 and Figure 6 It can be seen that, under the same power distribution network structure, the transmission loss of microstrip lines differs significantly between these two different transmission media. For example, as... Figure 5 and Figure 6 As shown, at a frequency of 12.5 GHz, the transmission loss of air transmission medium is reduced by 2.2111 dB compared to liquid crystal transmission medium. Therefore, converting part of the liquid crystal into air will greatly improve the transmission efficiency of microstrip lines.

[0039] Turning Figure 4Due to the change in transmission medium, the widths of the first microstrip line 211 and the second microstrip line 207 differ even with the same thickness and characteristic impedance under different transmission media. To reduce transmission loss, a second impedance transformer 215 can be added at the connection between the first microstrip line 211 and the second microstrip line 207. The second impedance transformer 215 starts at the baffle 210, and its length and linewidth are determined by the dielectric constant of the baffle 210 (specifically, the sealing adhesive). That is, different types of baffles 210 correspond to second impedance transformers 215 of different lengths and widths.

[0040] Furthermore, embodiments of the present invention also provide a communication device that employs any of the aforementioned liquid crystal antennas.

[0041] In such communication equipment, a liquid crystal area is provided in the region where the phase shifter function is required to ensure the large-angle phase shift capability of the phase shifter. In other regions, the power distribution network uses a different transmission medium than the liquid crystal, which has a lower dielectric loss angle than the liquid crystal. By replacing the transmission medium in regions other than the area where the phase shifter function is required with a transmission medium with a smaller dielectric loss angle (i.e., lower energy loss per unit volume), the power distribution network of the liquid crystal antenna in the communication equipment can significantly reduce the transmission loss generated by the liquid crystal in the power distribution network while ensuring that the input signal is evenly distributed to each array element with equal amplitude and phase.

[0042] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising," "including," etc., mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The terms "connection," "coupled," etc., are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. It should be noted that, without conflict, the features in the above embodiments can be used in any combination.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A liquid crystal antenna, comprising: Power distribution networks, including: Multiple cascaded power dividers, wherein each power divider includes a first microstrip line, a transmission medium region, a reference electrode, and a first impedance transformer; Phase shifter, including liquid crystal area and second microstrip line; Second impedance transformer; and Frame sealing adhesive Wherein, the tangent of the dielectric loss angle of the transmission medium in the transmission medium region is smaller than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal region, and the first microstrip line and the second microstrip line have different widths. The first microstrip line includes multiple microstrip lines with different impedances. The first impedance converter is electrically coupled between the first microstrip lines with different impedances, and the second impedance converter is electrically coupled between adjacent first microstrip lines and second microstrip lines. The transmission medium region is separated from the adjacent liquid crystal region by the sealing adhesive.

2. The liquid crystal antenna according to claim 1, wherein, The transmission medium in the transmission medium area is air.

3. The liquid crystal antenna according to claim 1, wherein, The width of the first microstrip line satisfies the following formula: in, This represents the characteristic impedance of the first microstrip line. This represents the effective dielectric constant of the transmission medium in the transmission medium region. This represents the permeability of the transmission medium in the transmission medium region. Indicates the width of the first microstrip line. This indicates the thickness of the transmission medium region.

4. A liquid crystal antenna, comprising: A first substrate and a second substrate arranged opposite to each other; Multiple radiating elements disposed on the side of the first substrate away from the second substrate; A power distribution network configured to feed electromagnetic signals to the plurality of radiating elements, the power distribution network comprising a plurality of cascaded power dividers, wherein each power divider includes: A transmission medium region is disposed between the first substrate and the second substrate; A first microstrip line is disposed between the second substrate and the transmission medium region; A first reference electrode disposed between the first substrate and the transmission medium region; and First impedance transformer, Phase shifter, the phase shifter comprising: Multiple liquid crystal regions are disposed between the first substrate and the second substrate; A second reference electrode is disposed between the first substrate and the plurality of liquid crystal regions; and A second microstrip line is disposed between the second substrate and the plurality of liquid crystal regions; Second impedance transformer; and Frame sealing adhesive The plurality of liquid crystal regions correspond one-to-one with the plurality of radiating elements, and the orthographic projection of each radiating element and the corresponding liquid crystal region on the second substrate at least partially overlaps, and the transmission medium region of each power divider is disposed between adjacent liquid crystal regions. Wherein, the tangent of the dielectric loss angle of the transmission medium in the transmission medium region is smaller than the tangent of the dielectric loss angle of the liquid crystal in the liquid crystal region, and the first microstrip line and the second microstrip line have different widths. The first microstrip line includes multiple microstrip lines with different impedances. The first impedance converter is electrically coupled between the first microstrip lines with different impedances, and the second impedance converter is electrically coupled between adjacent first microstrip lines and second microstrip lines. The transmission medium region and the adjacent liquid crystal region are separated by the sealing adhesive.

5. The liquid crystal antenna according to claim 4, wherein, The width of the second microstrip line satisfies the following formula: in, This represents the characteristic impedance of the second microstrip line. This represents the effective dielectric constant of the liquid crystal in the liquid crystal region. This represents the permeability of the liquid crystal in the liquid crystal region. Indicates the width of the second microstrip line. This indicates the thickness of the liquid crystal region.

6. A communication device comprising a liquid crystal antenna according to any one of claims 1-3 or any one of claims 4-5.

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