Ultra-wideband Wilkinson power divider based on liquid crystal material

Abstract

The invention provides an ultra-wideband Wilkinson power divider based on a liquid crystal material, relates to the technical field of microwaves, and completes impedance matching between transmission lines by designing the length and characteristic impedance of the transmission lines and adopting a specific isolation resistor structure. Uniform distribution and isolation of microwave signals in multiple layers of media including a liquid crystal layer are achieved. Modeling simulation is carried out on the power divider in three-dimensional electromagnetic field simulation software, the simulation result shows that the overall insertion loss of the power divider is smaller than 3.6 dB, and the relative bandwidth reaches 100%.

Description

Technical Field

[0001] The invention belongs to the field of radio frequency and microwave electronics, and in particular relates to an ultra-wideband Wilkinson power divider based on liquid crystal materials. Background Art

[0002] The power divider was invented in the 1940s. Since then, researchers have made various attempts to optimize the performance of the power divider and designed 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 and have become one of the most 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 the characteristics of high isolation compared to the T-type power divider. In 1968, SBCOHN first proposed the use of multi-stage ladder impedance transformation to expand the bandwidth of the Wilkinson power divider. The principle was explained through the odd-even mode analysis method, and the design method and design results were given. Subsequent personnel only need to look up the table to design a wide-band Wilkinson power divider with excellent performance. In 1977, NOBUO NAGAI first proposed a planar structure power divider, replacing the previous coaxial line structure with a planar transmission line and isolation resistor, which is easier to process and integrate, making PCB version power dividers widely used. Summary of the invention

[0004] In order to solve the above technical problems and realize signal distribution and isolation in the presence of a variable dielectric constant medium, the present invention provides an ultra-wideband Wilkinson power divider based on liquid crystal material, which realizes equal power distribution of microwave signals in a multi-layer medium including a liquid crystal layer, has the advantages of low loss and high isolation, and has a wide working bandwidth.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] An ultra-wideband Wilkinson power divider based on liquid crystal material comprises a lower floor, a dielectric substrate, a lower glass substrate, a liquid crystal layer, an upper glass substrate, and an upper floor stacked in sequence from bottom to top, wherein:

[0007] A metal strip unit and a chip resistor unit are also included between the dielectric substrate and the lower glass substrate, and the signal is evenly distributed and isolated through the metal strip unit and the chip resistor unit;

[0008] The metal strip unit comprises a plurality of strip lines connected in sequence, and the line widths are all different;

[0009] The chip resistor unit includes a plurality of resistors for isolation, and the resistors are distributed between the strip lines of the metal strip, and the impedances of the resistors are different.

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

[0011] Furthermore, the number of the patch resistors is the same as the transformation order N described in the previous step, the sizes of the patch resistors are the same, and the impedance sizes are different.

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

[0013] Furthermore, the metal strip unit includes a plurality of metal strips connected in sequence, wherein:

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

[0015] The second metal strip is a rectangular frame-shaped strip line with an open end, and the first metal strip is connected to the unopened end of the rectangular frame-shaped strip line of the second metal strip;

[0016] The third metal strip is a T-shaped frame strip line, wherein the T-shaped frame strip line includes a rectangular frame strip line with an opening at one end and two parallel straight strip lines connected to the opening at one end, and 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 frame-like strip line, and the T-shaped frame-like strip line includes a rectangular frame-shaped strip line with openings at both ends and two parallel straight-line strip lines connected to one of the openings, and the fourth metal strip is connected to the third metal strip through the two parallel straight-line strip lines of the fourth metal strip;

[0018] The fifth metal strip is two symmetrically placed inverted L-shaped strip lines, the short sides of the two inverted L-shaped strip lines are parallel and respectively connected to the other end openings of the rectangular frame-shaped strip line of the fourth metal strip, and the long sides of the two inverted L-shaped strip lines extend away from each other, serving as a left output port and a 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] The present invention is based on transmission line theory and impedance transformation design, and realizes an ultra-wideband Wilkinson power divider based on liquid crystal material. The structure can adapt to the variable dielectric constant characteristics of the liquid crystal layer in the multi-layer dielectric layer, and has the advantages of low insertion loss, high isolation and ultra-wide operating frequency band. The overall insertion loss is less than 3.6dB. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1 A schematic diagram of the three-dimensional structure of an ultra-wideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0024] Figure 2 A top view of an ultra-wideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0025] Figure 3 A side view of an ultra-wideband Wilkinson power divider based on liquid crystal material according to the present invention;

[0026] Figure 4 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 Schematic diagram of S21 of the ultra-wideband Wilkinson power divider under different liquid crystal dielectric constants in an embodiment of the present invention;

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

[0029] Reference numerals:

[0030] 1. Dielectric substrate, 2. Lower glass substrate, 3. Liquid crystal layer, 4. Upper glass substrate, 5. Lower floor, 6. Upper floor, 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. Chip resistor unit, 801. First chip resistor, 802. Second chip resistor, 803. Third chip resistor, 901. Left output port, 902. Right output port, 10. Input port. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The ultra-wideband Wilkinson power divider based on liquid crystal material of the present invention can be regarded as a signal power distribution structure based on transmission line, which realizes signal distribution by designing the length and characteristic impedance of the transmission line. This structure presents a bandpass characteristic and is commonly used in the feeding network of antenna array. Setting isolation resistors between 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 working bandwidth of the power divider.

[0033] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, but are not intended to limit the present invention.

[0034] like Figure 1-Figure 3 As shown, it is a three-dimensional schematic diagram, a top view and a side view of the ultra-wideband Wilkinson power divider based on liquid crystal material of the present invention, which includes a lower floor 5, a dielectric substrate 1, a lower glass substrate 2, a liquid crystal layer 3, an upper glass substrate 4, and an upper floor 6 stacked in sequence from bottom to top. Among them, the dielectric substrate 1 is made of Rogers 4350 (Rogers4350), with a thickness of 0.258mm and a relative dielectric constant of 3.66; the relative dielectric constants of the lower glass substrate 2 and the upper glass substrate 4 are both 5.5, and the thickness is 0.1mm; the relative dielectric constant of the liquid crystal layer 3 is between 2.46 and 3.57, and the thickness is 0.1mm. The liquid crystal of the liquid crystal layer 3 is an anisotropic material, and its relative dielectric constant can change continuously with the change of the bias voltage.

[0035] like Figure 2-Figure 3As shown, the order of the ultra-wideband Wilkinson power divider of the present invention is 3, and it also includes a metal strip unit 7 and a patch resistor unit 8. The impedance transformation part of the metal strip unit 7 adopts a Chebyshev multi-section matching transformer to design a characteristic impedance. The metal strip unit 7 and the patch resistor unit 8 are located between the dielectric substrate 1 and the lower glass substrate 2. The metal strip unit 7 includes a plurality of metal strips connected in sequence, wherein the first metal strip 701 is a straight strip line, one end of which is used as an input port 10, and the other end is connected to the second metal strip 702, the second metal strip 702 is a rectangular frame strip line with an open end, the first metal strip 701 is connected to the unopened end of the rectangular frame strip line of the second metal strip 702, and the third metal strip 703 is a T-frame strip line, and the T-frame strip line includes a rectangular frame strip line with an open end and a rectangular frame strip line connected to an open end. The third metal strip 703 is connected to the second metal strip 702 through two parallel straight strip lines of the T-frame strip line of the third metal strip 703. The fourth metal strip 704 is a quasi-T-frame strip line, and the quasi-T-frame strip line includes a rectangular frame strip line with openings at both ends and two parallel straight strip lines connected to one end opening. The fourth metal strip 704 is connected to the third metal strip 703 through two parallel straight strip lines of the fourth metal strip 704. The fifth metal strip 705 is two symmetrically placed inverted L-shaped strip lines, the short sides of the two inverted L-shaped strip lines are parallel and respectively connected to the other end opening of the rectangular frame strip line of the fourth metal strip 704, and the long sides of the two inverted L-shaped strip lines extend in directions away from each other, respectively, as the left output port 901 and the right output port 902. The signal enters the metal strip unit 7 from the input port 10, passes through the first metal strip 701, is split into two, and then passes through the second, third, fourth, and fifth metal strips 702, 703, 704, and 705 in sequence to reach the left output port 901 and the right output port 902. The line widths of the first, second, third, fourth, and fifth metal strips 701, 702, 703, 704, and 705 are different, which are 0.26 mm, 0.059 mm, 0.12 mm, 0.192 mm, and 0.26 mm respectively; wherein the lengths of the second, third, and fourth metal strips 702, 703, and 704 are all one-quarter of the medium wavelength, which is 13 mm;

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

[0037] like Figure 4 As shown, it is a schematic diagram of S11 under different liquid crystal dielectric constants of the ultra-wideband Wilkinson power divider in an embodiment of the present invention. The liquid crystal dielectric constant takes values ​​of 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 As shown, it is a schematic diagram of the insertion loss S21 between the input port 10 and the left output port 901 and the right output port 902 under different liquid crystal dielectric constants of the ultra-wideband Wilkinson power divider in an embodiment of the present invention. The liquid crystal dielectric constant takes values ​​of 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 As shown, it is a schematic diagram of the isolation S23 between the output port 901 and the output port 902 under different liquid crystal dielectric constants of the ultra-wideband Wilkinson power divider in an embodiment of the present invention. The liquid crystal dielectric constant takes values ​​of 2.46, 2.66, 2.86, 3.06, 3.26, 3.46, and 3.57. Under different liquid crystal dielectric constants, the power divider isolation is less than -15dB.

[0040] The present invention is a power divider based on liquid crystal materials, which can realize equal power distribution of signals in a medium including a liquid crystal layer and a glass layer without cross-layer propagation, and can maintain good transmission characteristics when the dielectric constant of the liquid crystal changes, thereby solving the problem that the implementation method of cross-layer transmission of signals is relatively complicated and has high loss because holes cannot be punched in the liquid crystal layer and the glass layer.

[0041] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. An ultra-wideband Wilkinson power divider based on liquid crystal material, characterized in that: It includes a lower floor, a dielectric substrate, a lower glass substrate, a liquid crystal layer, an upper glass substrate, and an upper floor stacked in sequence from bottom to top, wherein: A metal strip unit and a chip resistor unit are also included between the dielectric substrate and the lower glass substrate, and the signal is evenly distributed and isolated through the metal strip unit and the chip resistor unit; The metal strip unit comprises a plurality of strip lines connected in sequence, and the line widths are all different; The chip resistor unit includes a plurality of resistors for isolation, and the resistors are distributed between the strip lines of the metal strip, and the impedances of the resistors are different.

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

3. The ultra-wideband Wilkinson power divider based on liquid crystal material according to claim 1, characterized in that: The number of the patch resistors is the same as the transformation order N, the sizes of the patch resistors are the same, and the impedance sizes are 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 dielectric constant 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 a plurality of metal strips connected in sequence, wherein: The first metal strip is a straight strip line, one end of which serves as an input port and the other end of which is connected to the second metal strip; The second metal strip is a rectangular frame-shaped strip line with an open end, and the first metal strip is connected to the unopened end of the rectangular frame-shaped strip line of the second metal strip; The third metal strip is a T-shaped frame strip line, wherein the T-shaped frame strip line includes a rectangular frame strip line with an opening at one end and two parallel straight strip lines connected to the opening at one end, and 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 frame-like strip line, and the T-shaped frame-like strip line includes a rectangular frame-shaped strip line with openings at both ends and two parallel straight-line strip lines connected to one of the openings, and the fourth metal strip is connected to the third metal strip through the two parallel straight-line strip lines of the fourth metal strip; The fifth metal strip is two symmetrically placed inverted L-shaped strip lines, the short sides of the two inverted L-shaped strip lines are parallel and respectively connected to the other end openings of the rectangular frame-shaped strip line of the fourth metal strip, and the long sides of the two inverted L-shaped strip lines extend away from each other, serving as a left output port and a 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 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.

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