Microstrip Dual-Path Coupled Resonator Filter

Abstract

The present invention relates to the field of wireless communication technologies, and provides a microstrip dual-path coupled resonator filter. The microstrip dual-path coupled resonator filter includes a metal layer, a silicon substrate stacked on the metal layer, and a filter structure stacked on the silicon substrate; the filter structure passes through the silicon substrate and is electrically connected to the metal layer; the filter structure includes two microstrip transmission lines stacked and fixed on the silicon substrate and oppositely arranged along a first direction, two open-circuit microstrip resonators, a short-circuit resonator, and a tightly coupled feeding structure; the two microstrip transmission lines and the two open-circuit microstrip resonators are arranged in an interleaved manner, and the open-circuit microstrip resonators and the short-circuit resonator are spaced from the two microstrip transmission lines respectively; each microstrip transmission line is configured with two tightly coupled feeding structures, and the other ends of the two tightly coupled feeding structures are respectively connected to the two open-circuit microstrip resonators. The microstrip dual-path coupled resonator filter of the present invention has high integration and reliability.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly to a microstrip dual-path coupled resonator filter. Background Art

[0002] Filters are essential components in multi-band wireless communication. With the rapid development of wireless communication technologies, modern communication systems have increasingly strict requirements for the performance of filters. As an important component in a communication system, the performance of a filter directly affects the overall working efficiency and quality of the system. Existing filter technologies have some deficiencies, such as narrow frequency bands, large insertion losses, poor out-of-band rejection, etc. These defects limit the application of filters in broadband communication systems, especially in applications in the microwave and millimeter-wave bands that require high performance and low losses, where the performance of traditional filters cannot meet the requirements.

[0003] Currently, microstrip filters are widely used in various communication devices due to their advantages such as small volume, light weight, and easy integration. Commonly used microstrip filters include an intermediate dielectric substrate, a front single-section stepped impedance resonator, a front feeder line, a back ground metal, and a defected ground structure etched on the ground metal on the back. By designing the front single-section stepped impedance resonator to achieve low-pass filtering characteristics, this low-pass filtering has high frequency selection characteristics, and then combined with the defected ground structure etched on the back, using the notch characteristics of the defected ground structure, a low-pass filter with a wide stopband and high frequency selection characteristics is achieved by reasonably designing the size and number of the defected ground structure.

[0004] However, existing microstrip filters still face many challenges in design and manufacturing. The above-mentioned structures are more likely to lead to complex design, high manufacturing process requirements, poor device performance and reliability, etc. Summary of the Invention

[0005] Aiming at the above deficiencies of the prior art, the present invention proposes a microstrip dual-path coupled resonator filter to solve the problems of complex structure and poor reliability of existing microstrip dual-path coupled resonator filters.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An embodiment of the present invention provides a microstrip dual-path coupled resonator filter. The microstrip dual-path coupled resonator filter includes a metal layer, a silicon substrate stacked on the metal layer, and a filter structure stacked on the silicon substrate; the filter structure passes through the silicon substrate and is electrically connected to the metal layer;

[0008] The filter structure includes two microstrip transmission lines stacked and fixed on the silicon substrate and oppositely arranged in a first direction, two open - circuit microstrip resonators stacked on the silicon substrate and oppositely arranged in a second direction, a short - circuit resonator connected between the two open - circuit microstrip resonators, and a tightly - coupled feeding structure; the two microstrip transmission lines and the two open - circuit microstrip resonators are arranged in an interleaved manner, and the open - circuit microstrip resonators and the short - circuit resonator are spaced apart from the two microstrip transmission lines respectively; each microstrip transmission line is configured with two tightly - coupled feeding structures, and one end of each of the two tightly - coupled feeding structures is respectively connected to the microstrip transmission line, and the other end of each of the two tightly - coupled feeding structures is respectively connected to the two open - circuit microstrip resonators; the two microstrip transmission lines are used as the feeding ports of the filter structure.

[0009] The short - circuit resonator includes a short - circuit resonator body in a rhombus structure, a plurality of through - holes penetrating the short - circuit resonator body, and two first metal lines respectively extending reversely from opposite sides of the short - circuit resonator body along the second direction. One end of each of the two first metal lines far from the short - circuit resonator body is fixedly connected to the two open - circuit microstrip resonators. The inner surfaces of all the through - holes are plated with copper, and the through - holes penetrate the silicon substrate and are connected to the surface of the metal layer close to the silicon substrate.

[0010] Preferably, the short - circuit resonator body is made of a ring - shaped rhombus metal sheet.

[0011] Preferably, the first direction is perpendicular to the second direction, the filter structure is an axisymmetric structure with the straight line where the first metal line is located as the axis, and the filter structure is an axisymmetric structure with the straight line where the microstrip transmission line is located as the axis.

[0012] Preferably, the microstrip transmission line includes a transmission line body arranged on the silicon substrate and extending along the first direction, and a first connection portion extending from the transmission line body toward the side close to the short - circuit resonator; one end of the tightly - coupled feeding structure is connected to the first connection portion.

[0013] Preferably, the open - circuit microstrip resonator includes an open - circuit microstrip resonator body stacked on the silicon substrate and extending along the second direction, and a second connection portion extending from the open - circuit microstrip resonator body toward the side close to the short - circuit resonator; the second connection portion is fixed to the other end of the tightly - coupled feeding structure, and one end of the second connection portion close to the short - circuit resonator is fixed to the first metal line.

[0014] Preferably, each tightly - coupled feeding structure includes a second metal line and a third metal line that are parallel and spaced apart from each other.

[0015] In each of the two tightly coupled feeding structures configured for each microstrip transmission line, the first connecting portion includes a first contact portion and a second contact portion formed by the corresponding transmission line body extending respectively towards the directions close to the two tightly coupled structures. One ends of the two second metal wires close to the first connecting portion are respectively fixed to the first contact portion and the second contact portion, and the other ends of the two second metal wires away from the first connecting portion are respectively spaced from the corresponding two open - circuit microstrip resonators; one ends of the two third metal wires close to the first connecting portion are respectively spaced from the first connecting portion, and the other ends of the two third metal wires away from the first connecting portion are respectively fixedly connected to the two open - circuit microstrip resonators.

[0016] Preferably, the included angle formed at the connection of the third metal wire and the open - circuit microstrip resonator is an acute angle.

[0017] Preferably, the width and length of the microstrip transmission line are defined as W1 and L1 respectively, where W1 is 0.25 mm and L1 is 0.5 mm;

[0018] The width and length of the open - circuit microstrip resonator body are defined as W2 and L2 respectively, where W2 is 0.18 mm and L2 is 0.29 mm;

[0019] The lengths of the short - axis diagonal and the long - axis diagonal of the short - circuit resonator body are defined as W3 and L3 respectively, where W3 is 0.31 mm and L3 is 0.62 mm;

[0020] The second metal wire and the third metal wire have the same length, and are both defined as L4, L4 is 0.81 mm; the width of the second metal wire is defined as W4, W4 is 0.03 mm; the width of the third metal wire is defined as W5, W5 is 0.02 mm; the spacing between the second metal wire and the third metal wire is defined as S4, S4 is 0.03 mm.

[0021] Preferably, the silicon substrate is made of a high - resistivity silicon substrate with a dielectric constant of 11.9; the metal layer is made of copper material, and the filter structure is made of copper material.

[0022] Preferably, the through - hole is tubular, there are 32 through - holes, and they are arranged neatly and evenly directly below the short - circuit resonator body.

[0023] In the embodiments of the present invention, compared with the related art, by using a microstrip transmission line as the feeding port, signals can be effectively transmitted; the designs of the open-circuit microstrip resonator and the diamond-shaped short-circuit resonator improve the frequency selectivity and out-of-band rejection ability of the filter; the tightly coupled feeding structure further reduces the insertion loss and increases the bandwidth; meanwhile, the application of the silicon substrate enables the entire filter to have good thermal stability and mechanical stability. By using the silicon-based MEMS processing technology, the filter has high integration and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be described in detail below with reference to the accompanying drawings. Through the detailed description in combination with the following drawings, the above or other aspects of the present invention will become clearer and easier to understand. In the drawings:

[0025] Figure 1 is a schematic structural diagram of a microstrip dual-path coupled resonator filter provided by an embodiment of the present invention;

[0026] Figure 2 is a top view of a microstrip dual-path coupled resonator filter provided by an embodiment of the present invention;

[0027] Figure 3 is a schematic dimension diagram of a microstrip dual-path coupled resonator filter provided by an embodiment of the present invention;

[0028] Figure 4 is a performance simulation diagram of a microstrip dual-path coupled resonator filter provided by an embodiment of the present invention.

[0029] Among them, 100, microstrip dual-path coupled resonator filter; 1, metal layer; 2, filter structure; 21, microstrip transmission line; 211, transmission line body; 212, first connection part; 2121, first contact part; 2122, second contact part; 22, open-circuit microstrip resonator; 221, open-circuit microstrip resonator body; 222, second connection part; 23, short-circuit resonator; 231, short-circuit resonator body; 232, via hole; 233, first metal wire; 24, tightly coupled feeding structure; 241, second metal wire; 242, third metal wire; 3, silicon substrate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0031] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those of ordinary skill in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] Please refer to Figure 1 - Figure 2 As shown, an embodiment of the present invention provides a microstrip dual-path coupled resonator filter 100, and the microstrip dual-path coupled resonator filter 100 includes a metal layer 1, a silicon substrate 3 stacked on the metal layer 1, and a filter structure 2 stacked on the silicon substrate 3; the filter structure 2 passes through the silicon substrate 3 and is electrically connected to the metal layer 1.

[0034] The filter structure 2 includes two microstrip transmission lines 21 stacked and fixed on the silicon substrate 3 and oppositely arranged along a first direction, two open - circuit microstrip resonators 22 stacked on the silicon substrate 3 and oppositely arranged along a second direction, a short - circuit resonator 23 connected between the two open - circuit microstrip resonators 22, and a tightly - coupled feeding structure 24. The two microstrip transmission lines 21 and the two open - circuit microstrip resonators 22 are arranged in an interleaved manner, and the open - circuit microstrip resonators 22 and the short - circuit resonator 23 are spaced apart from the two microstrip transmission lines 21 respectively. Each of the microstrip transmission lines 21 is configured with two of the tightly - coupled feeding structures 24, and one end of each of the two tightly - coupled feeding structures 24 is respectively connected to the microstrip transmission line 21, and the other end of each of the two tightly - coupled feeding structures 24 is respectively connected to the two open - circuit microstrip resonators 22; the two microstrip transmission lines 21 are used as the feeding ports of the filter structure 2.

[0035] The short - circuit resonator 23 includes a short - circuit resonator body 231 in a rhombic structure, a plurality of through - holes 232 penetrating the short - circuit resonator body 231, and two first metal lines 233 respectively extending reversely from opposite sides of the short - circuit resonator body 231 along the second direction. One end of each of the two first metal lines 233 away from the short - circuit resonator body 231 is fixedly connected to the two open - circuit microstrip resonators 22 respectively. The inner surfaces of all the through - holes 232 are plated with copper, and the through - holes 232 penetrate the silicon substrate 3 and are connected to the surface of the metal layer 1 close to the silicon substrate 3. Plating the inner wall of the through - hole 232 enables the short - circuit resonator 23 to be electrically connected to the metal layer 1. By using the microstrip transmission line 21 as the feeding port, signals can be effectively transmitted; the design of the open - circuit microstrip resonator 22 and the rhombic short - circuit resonator 23 improves the frequency selectivity and out - of - band rejection ability of the filter. Connecting the microstrip transmission line 21 and the open - circuit microstrip resonator 22 through the tightly - coupled feeding structure 24 further reduces the insertion loss and increases the bandwidth. At the same time, the application of the silicon substrate 3 makes the entire filter have good thermal stability and mechanical stability. By using the silicon - based MEMS processing technology, the filter has high integration and reliability.

[0036] Among them, the MEMS processing technology (Microelectromechanical systems, MEMS) is a micro - structure processing technology ranging from the nanoscale to the millimeter scale.

[0037] In this embodiment, the short - circuit resonator body 231 is made of a ring - shaped rhombic metal sheet.

[0038] In this embodiment, the first direction is perpendicular to the second direction. The filter structure 2 is an axisymmetric structure with the straight line where the first metal wire 233 is located as the axis, and the filter structure 2 is an axisymmetric structure with the straight line where the microstrip transmission line 21 is located as the axis. The overall structure formed by the plurality of tightly coupled feeding structures 24 is spaced corresponding to the outer peripheral side of the short - circuit resonator 23, thereby forming a diamond - shaped tightly coupled feeding structure 24, further reducing the insertion loss.

[0039] In this embodiment, the microstrip transmission line 21 includes a transmission line body 211 disposed on the silicon substrate 3 and extending along the first direction, and a first connection portion 212 extending from the transmission line body 211 toward the side close to the short - circuit resonator 23; one end of the tightly coupled feeding structure 24 is connected to the first connection portion 212.

[0040] In this embodiment, the open - circuit microstrip resonator 22 includes an open - circuit microstrip resonator body 221 stacked on the silicon substrate 3 and extending along the second direction, and a second connection portion 222 extending from the open - circuit microstrip resonator body 221 toward the side close to the short - circuit resonator 23. The second connection portion 222 is fixed to the other end of the tightly coupled feeding structure 24, and one end of the second connection portion 222 close to the short - circuit resonator 23 is fixed to the first metal wire 233.

[0041] In this embodiment, each of the tightly coupled feeding structures 24 includes a second metal wire 241 and a third metal wire 242 that are parallel and spaced from each other.

[0042] Among the two tightly coupled feeding structures 24 configured for each microstrip transmission line 21, the first connection portion 212 includes a first contact portion 2121 and a second contact portion 2122 formed by the corresponding transmission line body 211 extending toward the directions close to the two tightly coupled structures respectively; one ends of the two second metal wires 241 close to the first connection portion 212 are respectively fixed to the first contact portion 2121 and the second contact portion 2122, and the other ends of the two second metal wires 241 away from the first connection portion 212 are spaced from the two open - circuit microstrip resonators 22 respectively. One ends of the two third metal wires 242 close to the first connection portion 212 are spaced from the corresponding first connection portion 212 respectively, and the other ends of the two third metal wires 242 away from the first connection portion 212 are fixedly connected to the two open - circuit microstrip resonators 22 respectively.

[0043] In this embodiment, the included angle formed at the connection between the third metal wire 242 and the open - circuit microstrip resonator 22 is an acute angle.

[0044] In this embodiment, referring to the appendix Figure 1 - Figure 3As shown, define the width and length of the microstrip transmission line 21 as W1 and L1 respectively, where W1 is 0.25 mm and L1 is 0.5 mm.

[0045] Define the width and length of the open - circuit microstrip resonator body 221 as W2 and L2 respectively, where W2 is 0.18 mm and L2 is 0.29 mm.

[0046] Define the lengths of the minor - axis diagonal and major - axis diagonal of the short - circuit resonator body 231 as W3 and L3 respectively, where W3 is 0.31 mm and L3 is 0.62 mm.

[0047] Define that the lengths of the second metal wire 241 and the third metal wire 242 are the same, both being L4, where L4 is 0.81 mm; the width of the second metal wire 241 is W4, where W4 is 0.03 mm; the width of the third metal wire 242 is W5, where W5 is 0.02 mm; the spacing between the second metal wire 241 and the third metal wire 242 is S4, where S4 is 0.03 mm.

[0048] Specifically, by determining the type of metal material and the type of the material of the silicon substrate 3, determining the length and width of the microstrip transmission line 21, the length and width of the open - circuit microstrip resonator 22, the size of the short - circuit resonator 23, the length, width and spacing of the two parallel metal wires of the tight - coupling feeding structure 24, and the size and thickness of the silicon substrate 3, a band - pass filter with wide - band, low insertion loss, and high out - of - band rejection that can be used for chip integration can be obtained.

[0049] Refer to the appendix Figure 4 As shown, this figure shows the S - parameter simulation curve measured by simulation. It can be seen from the figure that the operating frequency of the microstrip dual - path coupled resonator filter 100 is 20 GHz to 55 GHz, there are three different resonance points in the passband, the filtering insertion loss is less than 0.7 dB, the out - of - band rejection is below 30 dB, and the passband flatness is less than 0.2 dB.

[0050] In this embodiment, by adjusting the width of the microstrip transmission line 21, a microstrip transmission line 21 with a characteristic impedance corresponding to the frequency can be obtained, which plays a role in feeding and impedance matching in the design of the filter structure 2. By adjusting the length and width of the open-circuit microstrip resonator 22, when it acts as an open-circuit microstrip line, it is equivalent to a corresponding reactance value, playing a role in resonance at the corresponding frequency in the overall design of the filter structure 2. The size of the rhombic short-circuit resonator 23 is a key parameter for the short-circuit resonator 23 to be equivalent to a corresponding reactance value, playing a role in resonance at the corresponding frequency in the overall design of the filter. The open-circuit microstrip resonator 22 is directly connected to the rhombic short-circuit resonator 23, which can be equivalent to a series-parallel circuit of an inductor and a capacitor, used to realize band-pass filtering. The tightly coupled feeding structure 24 is a key link in the feeding structure, which not only restricts the resonance frequency of the filter, but also affects the insertion loss within the passband of the filter. By precisely controlling the parameters of the open-circuit microstrip resonator 22 and the rhombic short-circuit resonator 23, a broadband band-pass filter with an arbitrary frequency range can be obtained, and due to this connection method, a filter prototype with a higher out-of-band rejection degree can be obtained. In addition, the dual-path coupling structure increases the overall Q value of the filter. Therefore, the designed filter has obvious characteristics of low insertion loss and high out-of-band rejection among all broadband filters.

[0051] In this embodiment, the silicon substrate 3 is made of a high-resistance silicon substrate with a dielectric constant of 11.9; the metal layer 1 is made of copper material, and the filter structure 2 is made of copper material.

[0052] In this embodiment, the through hole 232 is tubular, and there are 32 through holes 232, which are arranged neatly and evenly directly below the short-circuit resonator body 231.

[0053] Specifically, in order to achieve excellent band-pass filtering performance and integration ability with the silicon-based chip, the silicon substrate 3 uses a high-resistance silicon substrate with a dielectric constant of 11.9. The metal layer 1 and the filter structure 2 are selected as pure copper with a high conductivity. The number of through holes 232 below the rhombic short-circuit resonator 23 is 32, and they are arranged neatly and evenly below the rhombic annular copper sheet. The through hole 232 is hollow and its inner surface is plated with metallic copper; both the type of metal material and the type of material of the silicon substrate 3 will affect the performance of the filter.

[0054] It should be noted that each of the embodiments described above with reference to the accompanying drawings is only used to illustrate the present invention rather than to limit the scope of the present invention. Those of ordinary skill in the art should understand that any modification or equivalent replacement made to the present invention without departing from the spirit and scope of the present invention shall be covered within the scope of the present invention. In addition, unless otherwise specified in the context, a word in the singular form includes the plural form, and vice versa. In addition, unless otherwise specified, all or part of any embodiment can be used in combination with all or part of any other embodiment.

Claims

1. A microstrip dual-path coupled resonator filter, characterized in that, The microstrip dual-path coupled resonator filter includes a metal layer, a silicon substrate stacked on the metal layer, and a filter structure stacked on the silicon substrate; the filter structure passes through the silicon substrate and is electrically connected to the metal layer; The filter structure includes two microstrip transmission lines stacked and fixed on the silicon substrate and oppositely arranged along a first direction, two open-circuit microstrip resonators stacked on the silicon substrate and oppositely arranged along a second direction, a short-circuit resonator connected between the two open-circuit microstrip resonators, and a tightly coupled feeding structure; The two microstrip transmission lines and the two open-circuit microstrip resonators are arranged in an interleaved manner, and the open-circuit microstrip resonators and the short-circuit resonator are respectively spaced from the two microstrip transmission lines; Each microstrip transmission line is configured with two of the tightly coupled feeding structures, and one end of each of the two tightly coupled feeding structures is respectively connected to the microstrip transmission line, and the other end of each of the two tightly coupled feeding structures is respectively connected to the two open-circuit microstrip resonators; the two microstrip transmission lines are used as the feeding ports of the filter structure; The short-circuit resonator includes a short-circuit resonator body in a diamond structure, a plurality of through holes penetrating the short-circuit resonator body, and two first metal lines respectively extending reversely from opposite sides of the short-circuit resonator body along the second direction. One end of each of the two first metal lines away from the short-circuit resonator body is fixedly connected to the two open-circuit microstrip resonators. The inner surfaces of all the through holes are plated with copper, and the through holes penetrate the silicon substrate and are connected to the surface of the metal layer close to the silicon substrate.

2. The microstrip dual-path coupled resonator filter according to claim 1, characterized in that The short-circuit resonator body is made of a ring-shaped diamond metal sheet.

3. The microstrip dual-path coupled resonator filter according to claim 1, characterized in that, The first direction and the second direction are perpendicular to each other. The filter structure is an axisymmetric structure with the straight line where the first metal line is located as the axis, and the filter structure is an axisymmetric structure with the straight line where the microstrip transmission line is located as the axis.

4. The microstrip dual-path coupled resonator filter according to claim 1, characterized in that, The microstrip transmission line includes a transmission line body disposed on the silicon substrate and extending along the first direction, and a first connection portion extending from the transmission line body toward the side close to the short-circuit resonator; one end of the tightly coupled feeding structure is connected to the first connection portion.

5. The microstrip dual-path coupled resonator filter according to claim 4, characterized in that, The open-circuit microstrip resonator includes an open-circuit microstrip resonator body stacked on the silicon substrate and extending along the second direction, and a second connection portion extending from the open-circuit microstrip resonator body toward the side close to the short-circuit resonator; the second connection portion is fixed to the other end of the tightly coupled feeding structure, and one end of the second connection portion close to the short-circuit resonator is fixed to the first metal line.

6. The microstrip dual-path coupled resonator filter according to claim 5, wherein Each of the tightly coupled feeding structures includes a second metal line and a third metal line that are parallel and spaced from each other; In each of the two tightly coupled feeding structures configured for each microstrip transmission line, the first connecting portion includes a first contact portion and a second contact portion formed by extending the corresponding transmission line body in directions close to the two tightly coupled feeding structures respectively. One ends of the two second metal wires close to the first connecting portion are respectively fixed to the first contact portion and the second contact portion, and the other ends of the two second metal wires away from the first connecting portion are respectively spaced from the corresponding two open - circuit microstrip resonators; one ends of the two third metal wires close to the first connecting portion are respectively spaced from the first connecting portion, and the other ends of the two third metal wires away from the first connecting portion are respectively fixedly connected to the two open - circuit microstrip resonators.

7. The microstrip dual-path coupled resonator filter according to claim 6, wherein The included angle formed at the connection between the third metal wire and the open - circuit microstrip resonator is an acute angle.

8. The microstrip dual-path coupled resonator filter according to claim 6, wherein Define the width and length of the microstrip transmission line as W1 and L1 respectively, where W1 is 0.25 mm and L1 is 0.5 mm; Define the width and length of the open - circuit microstrip resonator body as W2 and L2 respectively, where W2 is 0.18 mm and L2 is 0.29 mm; Define the lengths of the short - axis diagonal and the long - axis diagonal of the short - circuit resonator body as W3 and L3 respectively, where W3 is 0.31 mm and L3 is 0.62 mm; The second metal wire and the third metal wire have the same length, and are both defined as L4, L4 is 0.81 mm; define the width of the second metal wire as W4, W4 is 0.03 mm; define the width of the third metal wire as W5, W5 is 0.02 mm; define the spacing between the second metal wire and the third metal wire as S4, S4 is 0.03 mm.

9. The microstrip dual-path coupled resonator filter according to claim 1, wherein The silicon substrate is made of a high - resistivity silicon substrate with a dielectric constant of 11.9; the metal layer is made of copper material, and the filter structure is made of copper material.

10. The microstrip dual-path coupled resonator filter according to claim 1, wherein The through - hole is tubular, there are 32 through - holes, and they are arranged neatly and evenly directly below the short - circuit resonator body.

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