An ultra-wideband wilkinson power divider based on liquid crystal material

Abstract

The application provides a liquid crystal material-based ultra-wideband Wilkinson power divider, and relates to the technical field of microwaves, wherein the impedance matching between transmission lines is completed by designing the length and characteristic impedance of the transmission lines and adopting a specific isolation resistor structure, and the uniform distribution and isolation of microwave signals in a multilayer medium including a liquid crystal layer are realized.The power divider is modeled and simulated in three-dimensional electromagnetic field simulation software, and the simulation result shows that the overall insertion loss is less than 3.6dB, and the relative bandwidth reaches 100%.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency and microwave electronics, and specifically relates to an ultrawideband Wilkinson power divider based on liquid crystal materials. Background Technology

[0002] Power dividers were invented in the 1940s. Since then, researchers have made various attempts to optimize their performance, designing power dividers with different structures. Common power dividers include Wilkinson power dividers, Bagley polygonal power dividers, and Gysel power dividers. Among them, Wilkinson power dividers have been widely used in the field of microwave communications due to their superior performance, becoming one of the most widely used microwave passive devices.

[0003] In 1960, the Wilkinson power divider was invented by EJ Wilkinson. As a resistive power divider, the Wilkinson power divider has a higher isolation characteristic compared to the T-type power divider. In 1968, SBCOHN first proposed using multi-stage stepped impedance transformation to extend the bandwidth of the Wilkinson power divider. He explained the principle through odd-even mode analysis and provided design methods and results. Subsequent researchers could design high-performance broadband Wilkinson power dividers simply by referring to tables. In 1977, NOBUO NAGAI first proposed a planar power divider structure. Replacing the previous coaxial cable structure with a planar transmission line and isolation resistor made it easier to manufacture and integrate, leading to the widespread application of PCB-based power dividers. Summary of the Invention

[0004] To address the aforementioned technical problems and achieve signal distribution and isolation in the presence of a variable dielectric constant medium, this invention provides an ultrawideband Wilkinson power divider based on liquid crystal materials. This divider enables equal power distribution of microwave signals in a multilayer medium, including a liquid crystal layer, and offers advantages such as low loss, high isolation, and a wide operating bandwidth.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An ultrawideband Wilkinson power divider based on liquid crystal material includes, from bottom to top, a lower ground plane, a dielectric substrate, a lower glass substrate, a liquid crystal layer, an upper glass substrate, and an upper ground plane, wherein,

[0007] Between the dielectric substrate and the lower glass substrate, there are also metal strip units and chip resistor units, and the signal is evenly distributed and isolated through the metal strip units and chip resistor units;

[0008] The metal strip unit includes multiple strip lines connected in sequence, each with a different line width;

[0009] The surface mount resistor unit includes multiple resistors for isolation, which are distributed between the strip lines of the metal strip and have different impedances.

[0010] Furthermore, the impedance transformation section of the metal strip unit adopts a Chebyshev multi-section matched transformer to design the characteristic impedance, with a transformation order of N.

[0011] Furthermore, the number of surface mount resistors is the same as the transformation order N mentioned in the previous step, the size of the surface mount resistors is the same, and the impedance values ​​are different.

[0012] Furthermore, the lower glass substrate and the upper glass substrate have the same relative permittivity and thickness.

[0013] Furthermore, the metal strip unit comprises multiple metal strips connected in sequence, wherein,

[0014] The first metal strip is a straight strip line, with one end serving as an input port and the other end connected to the second metal strip;

[0015] The second metal strip is a rectangular frame-shaped strip with one end open, and the first metal strip is connected to the closed end of the rectangular frame-shaped strip of the second metal strip.

[0016] The third metal strip is a T-shaped strip line, which includes a rectangular strip line with one end open and two parallel straight strip lines connected to the one end open. The third metal strip is connected to the second metal strip through the two parallel straight strip lines of the third metal strip.

[0017] The fourth metal strip is a T-shaped strip line, which includes a rectangular strip line with openings at both ends and two parallel straight strip lines connected to one of the openings. The fourth metal strip is connected to the third metal strip through the two parallel straight strip lines of the fourth metal strip.

[0018] The fifth metal strip consists of two symmetrically placed inverted L-shaped strips. The short sides of the two inverted L-shaped strips are parallel and connected to the other end opening of the rectangular frame strip of the fourth metal strip. The long sides of the two inverted L-shaped strips extend away from each other, serving as the left output port and the right output port.

[0019] Furthermore, the chip resistor unit includes three chip resistors: the first chip resistor is located between two parallel straight strip lines of the third metal strip, the second chip resistor is located between two parallel straight strip lines of the fourth metal strip, and the third chip resistor is located between the short sides of two inverted L-shaped strip lines of the fifth metal strip.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] Based on transmission line theory and impedance transformation design, this invention realizes an ultrawideband Wilkinson power divider based on liquid crystal material. This structure can adapt to the variable dielectric constant characteristics of liquid crystal layers in multilayer dielectric layers, and has the advantages of low insertion loss, high isolation and ultrawide operating bandwidth. The overall insertion loss is less than 3.6dB. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a three-dimensional structural schematic diagram of an ultrawideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0024] Figure 2 This is a top view of an ultrawideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0025] Figure 3 This is a side view of an ultrawideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0026] Figure 4 This is a schematic diagram of S11 of the ultra-wideband Wilkinson power divider under different liquid crystal dielectric constants in an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of S21 for the ultra-wideband Wilkinson power divider under different liquid crystal dielectric constants in an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of S23 for the ultra-wideband Wilkinson power divider in an embodiment of the present invention under different liquid crystal dielectric constants.

[0029] Figure label:

[0030] 1. Dielectric substrate, 2. Lower glass substrate, 3. Liquid crystal layer, 4. Upper glass substrate, 5. Lower ground plane, 6. Upper ground plane, 7. Metal strip unit, 701. First metal strip, 702. Second metal strip, 703. Third metal strip, 704. Fourth metal strip, 705. Fifth metal strip, 8. Surface mount resistor unit, 801. First surface mount resistor, 802. Second surface mount resistor, 803. Third surface mount resistor, 901. Left output port, 902. Right output port, 10. Input port. Detailed Implementation

[0031] 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 clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The ultra-wideband Wilkinson power divider based on liquid crystal material of this invention can be regarded as a signal power distribution structure based on transmission lines. It achieves signal distribution by designing the length and characteristic impedance of the transmission lines. This structure exhibits bandpass characteristics and is often used in the feed network of antenna arrays. Setting isolation resistors between the metal strips can improve the isolation of the output port, and increasing the impedance transformation order of the power divider can also effectively increase the operating bandwidth of the power divider.

[0033] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, but this is not intended to limit the present invention.

[0034] like Figures 1-3 The diagram shows a three-dimensional schematic, top view, and side view of the ultra-wideband Wilkinson power divider based on liquid crystal material according to the present invention. It includes, from bottom to top, a lower ground plane 5, a dielectric substrate 1, a lower glass substrate 2, a liquid crystal layer 3, an upper glass substrate 4, and an upper ground plane 6, stacked sequentially. The dielectric substrate 1 is made of Rogers 4350 material, with a thickness of 0.258 mm and a relative permittivity of 3.66. The lower glass substrate 2 and the upper glass substrate 4 both have a relative permittivity of 5.5 and a thickness of 0.1 mm. The liquid crystal layer 3 has a relative permittivity between 2.46 and 3.57 and a thickness of 0.1 mm. The liquid crystal in the liquid crystal layer 3 is an anisotropic material, and its relative permittivity can continuously change with the bias voltage.

[0035] like Figures 2-3As shown, the ultra-wideband Wilkinson power divider of this invention has an order of 3 and also includes a metal strip unit 7 and a surface mount resistor unit 8. The impedance transformation section of the metal strip unit 7 adopts a Chebyshev multi-section matched converter to design the characteristic impedance. The metal strip unit 7 and the surface mount resistor unit 8 are located between the dielectric substrate 1 and the lower glass substrate 2. The metal strip unit 7 includes multiple metal strips connected in sequence. The first metal strip 701 is a straight strip line, with one end serving as the input port 10 and the other end connected to the second metal strip 702. The second metal strip 702 is a rectangular frame-shaped strip line with one open end. The first metal strip 701 and the second metal strip 702 are connected to the closed end of the rectangular frame-shaped strip line. The third metal strip 703 is a T-shaped strip line, which includes a rectangular frame-shaped strip line with one open end and a strip line connected to the open end. The third metal strip 703 and the second metal strip 702 are connected by two parallel straight-line strips through the T-shaped strip of the third metal strip 703. The fourth metal strip 704 is a T-shaped strip, which includes a rectangular strip with openings at both ends and two parallel straight-line strips connected to one of the openings. The fourth metal strip 704 and the third metal strip 703 are connected by two parallel straight-line strips of the fourth metal strip 704. The fifth metal strip 705 consists of two symmetrically placed inverted L-shaped strips. The short sides of the two inverted L-shaped strips are parallel and connected to the other opening of the rectangular strip of the fourth metal strip 704. The long sides of the two inverted L-shaped strips extend away from each other, serving as the left output port 901 and the right output port 902. The signal enters the metal strip unit 7 from input port 10, is split in two after passing through the first metal strip 701, and then sequentially passes through the second, third, fourth, and fifth metal strips 702, 703, 704, and 705 to reach the left output port 901 and the right output port 902. The linewidths of the first, second, third, fourth, and fifth metal strips 701, 702, 703, 704, and 705 are different, being 0.26 mm, 0.059 mm, 0.12 mm, 0.192 mm, and 0.26 mm, respectively; among them, the lengths of the second, third, and fourth metal strips 702, 703, and 704 are all one-quarter of the dielectric wavelength, which is 13 mm.

[0036] like Figures 2-3As shown, the surface mount resistor unit 8 includes three surface mount resistors. The first surface mount resistor 801 is located between two parallel straight lines of the third metal strip 703, the second surface mount resistor 802 is located between two parallel straight lines of the fourth metal strip 704, and the third surface mount resistor 803 is located between the short sides of the two inverted L-shaped lines of the fifth metal strip 705, used to improve the isolation of the power divider. The resistance values ​​of the first surface mount resistor, the second surface mount resistor, and the third surface mount resistor 801, 802, and 803 are different, being 105Ω, 211Ω, and 400Ω respectively.

[0037] like Figure 4 The diagram shown is a schematic of S11 for the ultra-wideband Wilkinson power divider under different liquid crystal dielectric constants in an embodiment of the present invention. The liquid crystal dielectric constants are 2.46, 2.66, 2.86, 3.06, 3.26, 3.46, and 3.57. Under different liquid crystal dielectric constants, the return loss of the power divider is less than -15dB.

[0038] like Figure 5 The diagram shows the insertion loss S21 between the input port 10 and the left output port 901 and right output port 902 of the ultra-wideband Wilkinson power divider in this embodiment of the invention under different liquid crystal dielectric constants. The liquid crystal dielectric constants are 2.46, 2.66, 2.86, 3.06, 3.26, 3.46 and 3.57. Under different liquid crystal dielectric constants, the insertion loss of the power divider is greater than -3.6dB.

[0039] like Figure 6 The diagram shows the isolation S23 between output port 901 and output port 902 of the ultra-wideband Wilkinson power divider under different liquid crystal dielectric constants in an embodiment of the present invention. The liquid crystal dielectric constants are 2.46, 2.66, 2.86, 3.06, 3.26, 3.46, and 3.57. Under different liquid crystal dielectric constants, the isolation of the power divider is less than -15dB.

[0040] This invention is a power divider based on liquid crystal materials, which enables equal power distribution of signals in a medium containing liquid crystal layers and glass layers without the need for cross-layer propagation. It also maintains good transmission characteristics when the dielectric constant of the liquid crystal changes, solving the problem that the implementation of cross-layer signal transmission is complicated and has high loss because holes cannot be drilled in the liquid crystal layer and glass layer.

[0041] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this invention.

Claims

1. An ultrawideband Wilkinson power divider based on liquid crystal material, characterized in that, It includes, from bottom to top, a lower ground plane, a dielectric substrate, a lower glass substrate, a liquid crystal layer, an upper glass substrate, and an upper ground plane, wherein, Between the dielectric substrate and the lower glass substrate, there are also metal strip units and chip resistor units, and the signal is evenly distributed and isolated through the metal strip units and chip resistor units; The metal strip unit includes multiple strip lines connected in sequence, each with a different line width; The surface mount resistor unit includes multiple resistors for isolation, which are distributed between the strip lines of the metal strip and have different impedances.

2. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 1, characterized in that, The impedance transformation section of the metal strip unit adopts a Chebyshev multi-section matched transformer to design the characteristic impedance, with a transformation order of N.

3. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 2, characterized in that, The number of surface mount resistors is the same as the transformation order N, the surface mount resistors are all the same size, and their impedances are all different.

4. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 1, characterized in that, The lower glass substrate and the upper glass substrate have the same relative permittivity and thickness.

5. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 1, characterized in that, The metal strip unit comprises multiple metal strips connected in sequence, wherein... The first metal strip is a straight strip line, with one end serving as an input port and the other end connected to the second metal strip; The second metal strip is a rectangular frame-shaped strip with one end open, and the first metal strip is connected to the closed end of the rectangular frame-shaped strip of the second metal strip. The third metal strip is a T-shaped strip line, which includes a rectangular strip line with one end open and two parallel straight strip lines connected to the one end open. The third metal strip is connected to the second metal strip through the two parallel straight strip lines of the third metal strip. The fourth metal strip is a T-shaped strip line, which includes a rectangular strip line with openings at both ends and two parallel straight strip lines connected to one of the openings. The fourth metal strip is connected to the third metal strip through the two parallel straight strip lines of the fourth metal strip. The fifth metal strip consists of two symmetrically placed inverted L-shaped strips. The short sides of the two inverted L-shaped strips are parallel and connected to the other end opening of the rectangular frame strip of the fourth metal strip. The long sides of the two inverted L-shaped strips extend away from each other, serving as the left output port and the right output port.

6. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 1, characterized in that, The chip resistor unit includes three chip resistors: the first chip resistor is located between two parallel straight strips of the third metal strip, the second chip resistor is located between two parallel straight strips of the fourth metal strip, and the third chip resistor is located between the short sides of two inverted L-shaped strips of the fifth metal strip.

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