A microstrip resonator with double-in and double-out structure and a microwave filter

Abstract

The application discloses a double-rotation-in-rotation-out structure microstrip resonator and microwave filter, and relates to the technical field of microwave communication. The opening end of the first rotation-in-rotation-out structure and the opening end of the second rotation-in-rotation-out structure are opposite and diagonally symmetrical. The first rotation-in-rotation-out structure and the second rotation-in-rotation-out structure are both double-line structures, which are wound in a character-shaped manner at a set initial position, and when wound to a preset terminal position, the inner line is elongated until a U-shaped structure surrounds the part wound in the character-shaped manner. The outer lines of the two double-line structures are connected through a first microstrip line. The double-line structure is composed of two parallel microstrip lines, and the two parallel microstrip lines are connected through a preset microstrip line at the corresponding set initial position. The application aims to solve the problem that it is difficult to achieve extremely weak coupling of the resonator at a small interval, and improve the stability of the coupling.

Description

Technical Field

[0001] This application relates to the field of microwave communication technology, and in particular to a microstrip resonator and microwave filter with a dual-spin-in / spin-out structure. Background Technology

[0002] With the rapid development of wireless communication technology, more and more communication frequency bands are being developed and utilized, making the space electromagnetic environment extremely complex. The performance requirements for microwave filters in high-performance microwave receivers are also increasing. An ideal microwave filter has rectangular filtering characteristics, capable of filtering out signals in the desired frequency band and completely filtering out signals in other frequency bands. However, due to factors such as microwave losses in metallic materials, the filtering performance of practical microwave filters differs significantly from that of ideal filters. Compared to conventional metals, high-temperature superconducting materials have a surface resistivity two to three orders of magnitude lower in the microwave band, making them extremely low. Resonators and filters made from high-temperature superconducting materials offer advantages such as low loss and high frequency selectivity, significantly improving the frequency selectivity and sensitivity of microwave receivers.

[0003] Microwave receivers that process narrow-band signals in complex electromagnetic environments require highly selective microwave filters with narrow or even extremely narrow passband characteristics. The required microwave filters should have features such as low loss within the wide passband and high suppression outside the passband.

[0004] The main challenges in designing narrow-passband microwave filters include high-quality factor resonator units, sufficiently weak coupling between adjacent resonators, and sufficiently weak parasitic coupling between non-adjacent resonators. Currently, the weakly coupled resonator design method is mainly used in narrow-passband filter design both domestically and internationally.

[0005] The study of weakly coupled resonator structures mainly includes hairpin resonators, spiral resonators, open-loop resonators, step impedance resonators, clip resonators, and their combinations and variations.

[0006] Hairpin resonators: In the early research on ultra-narrowband filters, hairpin resonators were a relatively typical weakly coupled resonator. Matthaei GL, Fenzi NO, Forse RJ, et al. Hairpin-comb filters for HTS and other narrow-band applications. IEEE transactions on microwave theory and techniques, 1997, 45(8): 1226-1231. A filter composed of parallel hairpin resonators was proposed. The open ends of the four hairpin resonators are all arranged in the same direction, like a comb. The electromagnetic coupling between adjacent resonators cancels each other out, which weakens the coupling between resonators to a certain extent.

[0007] Spiral resonators: Huang F. Ultra-compact superconducting narrow-band filters using single-and twin-spiral resonators. IEEE Transactions on Microwave Theory and Techniques, 2003, 51(2): 487-491. This paper proposes the design of ultra-narrowband high-temperature superconducting filters using single-spiral and twin-spiral resonators. Spiral resonators have a compact structure and relatively localized electromagnetic field, with weak coupling between adjacent resonators, making them suitable for fabricating narrowband filters. Single-spiral resonators are small in size and have good suppression characteristics for second harmonics. The advantage of twin-spiral resonators is that they can rapidly attenuate adjacent couplings as the spacing increases.

[0008] Open-loop resonator: Yi HR, Remillard SK, Abdelmonem A. A novel ultra-compact resonator for superconducting thin-film filters. IEEE Transactions on Microwave Theory and Techniques, 2003, 51(12): 2290-2296. A branched open-loop resonator is proposed. The resonator consists of three open-loop structures. The opening direction of the second open-loop structure is opposite to that of the first and third open-loop structures. The first and second, and the second and third open-loop structures are connected by branch lines. By combining the microstrip structure with the coplanar structure, the resonator has weak coupling characteristics.

[0009] Step Impedance Resonator: Kwak JS, Jong Hyun L, Jin Pyo H, et al. Narrowpassband high-temperature superconducting filters of highly compact sizes for personal communication service applications. IEEE Transactions on Applied Superconductivity, 2003, 13(1): 17-19. A helical bent-line resonator is proposed. This resonator consists of large-area low-impedance lines on both sides and a lumped-parameter inductor in the middle. The former increases the resonator's capacitance to ground, while the latter weakens magnetic field radiation, realizing the weak coupling characteristics between resonators.

[0010] Clip-shaped resonator: Tsuzuki SMI, Shen Y, Berkowitz S. Ultra-selective 22-pole 10-transmission zero superconducting bandpass filter surpasses 50-pole Chebyshev filter. IEEE Transactions on Microwave Theory and Techniques, 2002, 50(12): 2924-2929. A clip-shaped resonator with weak coupling characteristics and high unloaded Q value is proposed. In the clip-shaped resonator, the current on the microstrip line at any symmetrical position is in the opposite direction, which weakens the magnetic field radiated outward by the resonator, thereby reducing the spacing of the resonators.

[0011] In the aforementioned resonator and filter design methods, increasing the capacitance and inductance of the resonators, reducing the mutual capacitance and inductance between resonators, or using electromagnetic coupling cancellation methods can all weaken the coupling between resonators. However, the filter size is related not only to the resonator spacing but also to the size of the resonators themselves. Both factors should be considered comprehensively in the design of ultra-narrowband filters. Further research is needed to achieve weak coupling with small spacing and to further develop compact, high-performance ultra-narrowband high-temperature superconducting filters. Summary of the Invention

[0012] The purpose of this application is to provide a microstrip resonator and microwave filter with a dual-spin-in and spin-out structure, which can solve the problem of the difficulty in achieving extremely weak coupling in resonators with small spacing and improve the stability of coupling.

[0013] To achieve the above objectives, this application provides the following solution:

[0014] In a first aspect, this application provides a microstrip resonator with a dual screw-in and screw-out structure, comprising: a first screw-in and screw-out structure and a second screw-in and screw-out structure;

[0015] The first screw-in and screw-out structure and the second screw-in and screw-out structure are arranged vertically and connected to each other; the opening ends of the first screw-in and screw-out structure and the opening ends of the second screw-in and screw-out structure are opposite in direction and are diagonally symmetrical.

[0016] The first spiral-in spiral-out structure is obtained by first double-line structure, which is wound in a back-shaped manner at a first set initial position, and when it is wound to the first set end position, the inner line of the first double-line structure is extended until it is surrounded by a U-shaped structure after the part wound in the back-shaped manner is obtained.

[0017] The second spiral-in and spiral-out structure is obtained by the second double-line structure being wound in a zigzag shape at the second preset initial position, and when the winding reaches the second preset end position, the inner line of the second double-line structure is extended until it is surrounded by a U-shaped structure after the zigzag winding part is completed.

[0018] The outer line of the first bilinear structure and the outer line of the second bilinear structure are connected by a first microstrip line; the first microstrip line is perpendicular to the outer lines of both the first and second bilinear structures.

[0019] The first set initial position and the second set initial position are different, and the first preset end position and the second preset end position are also different;

[0020] Both the first and second bilinear structures are composed of two parallel microstrip lines; the two parallel microstrip lines are connected by a preset microstrip line at corresponding initial positions; the preset microstrip line is perpendicular to the two parallel microstrip lines.

[0021] Optionally, the spacing between the two parallel microstrip lines is 0.08 mm.

[0022] Optionally, the linewidth of the microstrip line is 0.08 mm.

[0023] Optionally, the interval for the wrapping in the zigzag shape is 0.08 mm.

[0024] Optionally, the U-shaped structure in the first spiral-in / spin-out structure includes: a first part microstrip line, a second part microstrip line, and a third part microstrip line; the U-shaped structure in the second spiral-in / spin-out structure includes: a fourth part microstrip line, a fifth part microstrip line, and a sixth part microstrip line.

[0025] The first part of the microstrip line, the third part of the microstrip line, the fourth part of the microstrip line, and the sixth part of the microstrip line are all parallel to each other;

[0026] The second part of the microstrip line and the fifth part of the microstrip line are parallel to each other;

[0027] The second part of the microstrip line is perpendicular to the first part of the microstrip line and the third part of the microstrip line, respectively; the fifth part of the microstrip line is perpendicular to the fourth part of the microstrip line and the sixth part of the microstrip line, respectively.

[0028] Optionally, the length of the first part of the microstrip line is 1.68 mm; the length of the second part of the microstrip line is 1.96 mm; the length of the fifth part of the microstrip line is 1.96 mm; and the length of the sixth part of the microstrip line is 1.68 mm.

[0029] Optionally, the length of the first part of the microstrip line is 1.68 mm; the length of the second part of the microstrip line is 2.14 mm; the length of the fifth part of the microstrip line is 1.78 mm; and the length of the sixth part of the microstrip line is 1.68 mm.

[0030] Secondly, this application provides a microwave filter, including: an input feed line, an output feed line, and a coupling structure; the coupling structure is obtained by coupling at least two microstrip resonators with a dual-spin-in-spin-out structure.

[0031] Both the input feed line and the output feed line are connected to the coupling structure.

[0032] Optionally, if the coupling structure uses an asymmetric double-spin-in / spin-out microstrip resonator, the spacing between each pair of microstrip resonators is 1 mm; the asymmetric double-spin-in / spin-out microstrip resonator is a microstrip resonator in which the length of the second part of the microstrip line of the U-shaped structure is different from the length of the fifth part of the microstrip line.

[0033] Optionally, if the coupling structure uses a microstrip resonator with the same length of the second part of the U-shaped microstrip line as the fifth part of the microstrip line, then the spacing between every two microstrip resonators is 1.4 mm.

[0034] According to the specific embodiments provided in this application, this application has the following technical effects:

[0035] This application provides a microstrip resonator and microwave filter with a dual-screw-in / screw-out structure. Both the first and second screw-in / screw-out structures are formed by winding bilinear structures in a U-shape at a predetermined initial position. Upon reaching a predetermined endpoint, the inner line is extended until a U-shaped structure surrounds the U-shaped winding portion. The outer lines of the two bilinear structures are connected by a first microstrip line. Each bilinear structure consists of two parallel microstrip lines, which are connected by a predetermined microstrip line at their respective initial positions. Furthermore, the opening ends of the first and second screw-in / screw-out structures face opposite directions and are diagonally symmetrical. Due to the microstrip resonator's structural design, the spiral portion forms magnetic coupling, and the upper and lower opening ends form electrical coupling, enabling the coupling between resonators to approach a very weak value of zero, thus solving the problem of achieving extremely weak coupling in small-pitch resonators. Since the electrical and magnetic couplings between resonators cancel each other out, adjacent coupling can be further reduced, thereby improving coupling stability. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of a dual-screw-in / screw-out resonator.

[0038] Figure 2 This is a schematic diagram of a double-screw-in / screw-out resonator; where, Figure 2 (a) is a schematic diagram of the first type of double-screw-in and screw-out resonator structure; Figure 2 (b) is a schematic diagram of the second type of double-screw-in and screw-out resonator structure;

[0039] Figure 3 This is a schematic diagram of the interstage coupling structure and equivalent circuit of an asymmetric double-spin-in / spin-out resonator; where... Figure 3 (a) is a schematic diagram of the coupling structure. Figure 3 (b) is a schematic diagram of the equivalent circuit;

[0040] Figure 4 The relationship between the interstage coupling strength of an asymmetric double-spin-in / spin-out resonator and the spacing.

[0041] Figure 5 This is a circuit diagram of a 6th-order ultra-narrow bandwidth superconducting filter;

[0042] Figure 6 The diagram shows the frequency response characteristics of a 6th-order ultranarrow bandwidth superconducting filter. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] The purpose of this application is to address the limitation of resonators in compact filter circuits, which struggle to maintain weak coupling at close range. An asymmetric double-screw-in / screw-out resonator with flexible and variable structural proportions is proposed, solving the problem of achieving extremely weak coupling with small spacing and improving coupling stability. It can be used to design miniaturized and stable ultra-narrow passband superconducting microwave filters.

[0045] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] This application provides a microstrip resonator with a dual screw-in and screw-out structure, comprising: a first screw-in and screw-out structure and a second screw-in and screw-out structure.

[0047] The first and second screw-in / screw-out structures are arranged vertically and connected to each other; the opening ends of the first and second screw-in / screw-out structures are opposite in direction and are diagonally symmetrical.

[0048] The first spiral-in and spiral-out structure is formed by the first double-line structure being wound in a zigzag shape at a first set initial position, and when the winding reaches the first preset end position, the inner line of the first double-line structure is extended until it is surrounded by a U-shaped structure after the zigzag winding part is completed.

[0049] The second spiral-in and spiral-out structure is formed by the second double-line structure being wound in a zigzag shape at the second preset initial position. When the winding reaches the second preset end position, the inner line of the second double-line structure is extended until it forms a U-shaped structure that surrounds the part that was wound in the zigzag shape.

[0050] The outer line of the first bilinear structure is connected to the outer line of the second bilinear structure via a first microstrip line; the first microstrip line is perpendicular to the outer lines of both the first and second bilinear structures.

[0051] The first and second preset initial positions are different, as are the first and second preset end positions.

[0052] Both the first and second bilinear structures are composed of two parallel microstrip lines; the two parallel microstrip lines are connected by a preset microstrip line at their corresponding initial positions; the preset microstrip line is perpendicular to the two parallel microstrip lines.

[0053] The structure of a microstrip resonator with a dual-spin-in / spin-out configuration can be... Figure 1 The structure shown.

[0054] by Figure 2 (a) For example, the red-filled part is obtained by wrapping a double-line structure in a zigzag shape. Figure 2 (b) formation process and Figure 2 (a) Same.

[0055] The spacing between the two parallel microstrip lines is 0.08 mm. The linewidth of the microstrip line is 0.08 mm. The interval between the zigzag windings is 0.08 mm.

[0056] In one embodiment, the U-shaped structure in the first spiral-in / spin-out structure includes: a first part microstrip line, a second part microstrip line, and a third part microstrip line; the U-shaped structure in the second spiral-in / spin-out structure includes: a fourth part microstrip line, a fifth part microstrip line, and a sixth part microstrip line.

[0057] Among them, the first, third, fourth and sixth microstrip lines are all parallel to each other; the second and fifth microstrip lines are parallel to each other.

[0058] The second microstrip line is perpendicular to the first and third microstrip lines, respectively; the fifth microstrip line is perpendicular to the fourth and sixth microstrip lines, respectively.

[0059] At fundamental frequency resonance, the current is mainly distributed in the helical portion of the microstrip line. The currents in adjacent microstrip lines of the screw-in / screw-out resonator are opposite, and the magnetic fields generated outside the resonator are partially canceled out, resulting in weak magnetic coupling between adjacent resonators at close range. The structure of a dual screw-in / screw-out microstrip resonator is as follows: Figure 2 As shown in (a).

[0060] At this point, the length of the first microstrip line is 1.68 mm; the length of the second microstrip line is 1.96 mm; the length of the fifth microstrip line is 1.96 mm; and the length of the sixth microstrip line is 1.68 mm.

[0061] The openings at both ends of the double-screw-in and screw-out structure face to the left and right. Under the condition of small spacing between adjacent components, the resonator coupling is dominated by electrical coupling. Since the electrical coupling and magnetic coupling between the resonators cancel each other out, the adjacent coupling can be further reduced.

[0062] Asymmetric double-spin-in / spin-out resonator, such as Figure 2 As shown in (b), by optimizing the ratio of the upper and lower spiral microstrip lines, the coupling between the asymmetric double-spin-in and spin-out resonators is made to approach a very weak value of zero.

[0063] At this point, the length of the first microstrip line is 1.68 mm; the length of the second microstrip line is 2.14 mm; the length of the fifth microstrip line is 1.78 mm; and the length of the sixth microstrip line is 1.68 mm.

[0064] like Figure 2 As shown in (b), the main optimization of the asymmetric double-screw-in and screw-out resonator is the longitudinal height of the upper part of the spiral. The height of the outermost ring is optimized from 1.96 mm to 2.14 mm. The longitudinal height of each microstrip line inside the spiral is also optimized and increased accordingly, while maintaining the microstrip line width of 0.08 mm and the spacing between microstrip lines of 0.08 mm.

[0065] The longitudinal height of the lower helix, the height of the outermost ring, was optimized from 1.96mm to 1.78mm. The longitudinal height of each microstrip line inside the helix was also optimized and increased accordingly, while maintaining the microstrip line width of 0.08mm and the spacing between microstrip lines of 0.08mm.

[0066] This application also provides a microwave filter, which includes an input feed line, an output feed line, and a coupling structure; the coupling structure is obtained by coupling at least two microstrip resonators with a dual-spin-in / spin-out structure. Both the input feed line and the output feed line are connected to the coupling structure.

[0067] If the coupling structure uses an asymmetric double-spin-in / spin-out microstrip resonator, the spacing between each pair of microstrip resonators is 1 mm. An asymmetric double-spin-in / spin-out microstrip resonator is a microstrip resonator in which the length of the second part of the microstrip line in the U-shaped structure is different from the length of the fifth part of the microstrip line.

[0068] In other words, the spiral sections of adjacent resonators form magnetic coupling, and the upper and lower open ends of the resonators form electrical coupling, thus forming electrical coupling between the resonators. The coupling structure and equivalent circuit are as follows: Figure 3 As shown. Among them, Figure 3 (a) is a schematic diagram of the coupling structure. Figure 3 In (a), H1 is the first length; H2 is the second length. Figure 3 (b) is a schematic diagram of the equivalent circuit. Figure 3 In (b), L1 is the first inductor, L2 is the second inductor; C1 is the first capacitor, C2 is the second capacitor. The relationship between the coupling strength and coupling distance between the resonators of an asymmetric double-spin-in / spin-out resonator is as follows: Figure 4 As shown, an extremely weak coupling state with coupling strength approaching zero was achieved under a 1mm spacing condition.

[0069] If the coupling structure uses a microstrip resonator with the same length of the second part of the U-shaped microstrip line as the fifth part of the microstrip line, then the spacing S between every two microstrip resonators is 1.4 mm.

[0070] With an optimized spacing of 1.4 mm, the coupling coefficient (also known as coupling strength) between two adjacent resonators reaches a near-zero minimum. The coupling strength curve is shown below. Figure 4 As shown.

[0071] By employing the microwave filter coupling matrix design method, based on the proposed asymmetric double-spin-in-spin-out resonator structure, 6th-order, 8th-order, and higher-order microwave filters can be designed, exhibiting extremely narrow wide passband characteristics and high out-of-band suppression characteristics. This allows the generation of superconducting microstrip filters, whose corresponding resonators and filter circuits can be fabricated using high-temperature superconducting materials, with magnesium oxide or lanthanum aluminate substrates used for the circuit substrates.

[0072] The input feed is located on one side of the first resonator, and the output feed is located on one side of the last resonator.

[0073] After the superconducting microstrip filter is fabricated, it is installed in a metal package. The input port and output ports of the multiplexer circuit are connected by a microwave coaxial connector, and then the metal package is used for encapsulation.

[0074] This application can be used to design ultra-narrow passband superconducting filters with planar microstrip structures, offering advantages such as high design efficiency, stable design results, and ease of design expansion. In practical applications, a sixth-order ultra-narrow passband superconducting filter with an operating frequency around 2.2 GHz was designed using the design method proposed in this application. The filter circuit diagram is shown below. Figure 5 As shown.

[0075] Figure 5 The superconducting filter circuit diagram is shown below. It has a total length of 18.8 mm and a total width of 8 mm. The black lines in the filter circuit represent microstrip lines and resonators. Six resonators are arranged side-by-side in the middle, with thicker lines representing the input and output feed lines on the left and right sides. The six resonators are placed symmetrically in the center. The spacing between the three resonators from left to right is S1 = 0.72 mm, S2 = 1.14 mm, and S3 = 0.76 mm. These three resonators are vertically staggered: the first resonator is higher than the second by Y1 = 0.06 mm, the second is higher than the third by Y2 = 0.10 mm, and the third is lower than the fourth by Y3 = 0.18 mm. W1 is the linewidth of the microstrip line in the resonator, which is 0.08 mm. G1 is the spacing between the microstrip lines in the resonator, which is 0.08 mm.

[0076] The filter has a passband bandwidth of 4.2MHz, and its schematic diagram is shown below. Figure 6 As shown.

[0077] In a double-screw-in / screw-out structure, the openings at both ends face left and right. Under conditions of small spacing between adjacent resonators, the coupling between them is weak. In an asymmetric double-screw-in / screw-out resonator, by optimizing the ratio of the upper and lower spiral microstrip lines, the coupling between the asymmetric double-screw-in / screw-out resonators approaches a very weak value of zero.

[0078] In an asymmetric double screw-in / screw-out resonator, adjacent screw sections form magnetic coupling, while the upper and lower open ends of the resonator form electrical coupling, resulting in electrical coupling between the resonators. The asymmetric double screw-in / screw-out resonator maintains weak coupling strength when the resonator spacing is around 1 mm, and the coupling strength approaches zero at a spacing of 1 mm, reaching an extremely weak coupling state.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A microstrip resonator with a dual screw-in / screw-out structure, characterized in that, The microstrip resonator with a dual screw-in and screw-out structure includes: a first screw-in and screw-out structure and a second screw-in and screw-out structure; The first screw-in and screw-out structure and the second screw-in and screw-out structure are arranged vertically and connected to each other; the opening ends of the first screw-in and screw-out structure and the opening ends of the second screw-in and screw-out structure are opposite in direction and are diagonally symmetrical. The first spiral-in spiral-out structure is obtained by first double-line structure, which is wound in a back-shaped manner at a first set initial position, and when it is wound to the first set end position, the inner line of the first double-line structure is extended until it is surrounded by a U-shaped structure after the part wound in the back-shaped manner is obtained. The second spiral-in and spiral-out structure is obtained by the second double-line structure being wound in a zigzag shape at the second preset initial position, and when the winding reaches the second preset end position, the inner line of the second double-line structure is extended until it is surrounded by a U-shaped structure after the zigzag winding part is completed. The outer line of the first bilinear structure and the outer line of the second bilinear structure are connected by a first microstrip line; the first microstrip line is perpendicular to the outer lines of both the first and second bilinear structures. The first set initial position and the second set initial position are different, and the first preset end position and the second preset end position are also different; Both the first and second bilinear structures are composed of two parallel microstrip lines; the two parallel microstrip lines are connected by a preset microstrip line at corresponding initial positions; the preset microstrip line is perpendicular to the two parallel microstrip lines.

2. The microstrip resonator with a dual screw-in / screw-out structure according to claim 1, characterized in that, The spacing between the two parallel microstrip lines is 0.08 mm.

3. The microstrip resonator with a dual screw-in / screw-out structure according to claim 1, characterized in that, The microstrip line has a linewidth of 0.08 mm.

4. The microstrip resonator with a dual screw-in / screw-out structure according to claim 1, characterized in that, The interval for the wrapping in a zigzag shape is 0.08mm.

5. The microstrip resonator with a dual screw-in / screw-out structure according to claim 1, characterized in that, The U-shaped structure in the first spiral-in / spin-out structure includes: a first part microstrip line, a second part microstrip line, and a third part microstrip line; the U-shaped structure in the second spiral-in / spin-out structure includes: a fourth part microstrip line, a fifth part microstrip line, and a sixth part microstrip line. The first part of the microstrip line, the third part of the microstrip line, the fourth part of the microstrip line, and the sixth part of the microstrip line are all parallel to each other; The second part of the microstrip line and the fifth part of the microstrip line are parallel to each other; The second part of the microstrip line is perpendicular to the first part of the microstrip line and the third part of the microstrip line, respectively; the fifth part of the microstrip line is perpendicular to the fourth part of the microstrip line and the sixth part of the microstrip line, respectively.

6. The microstrip resonator with a dual screw-in / screw-out structure according to claim 5, characterized in that, The length of the first part of the microstrip line is 1.68 mm; the length of the second part of the microstrip line is 1.96 mm; the length of the fifth part of the microstrip line is 1.96 mm; and the length of the sixth part of the microstrip line is 1.68 mm.

7. The microstrip resonator with a dual screw-in / screw-out structure according to claim 5, characterized in that, The length of the first part of the microstrip line is 1.68 mm; the length of the second part of the microstrip line is 2.14 mm; the length of the fifth part of the microstrip line is 1.78 mm; and the length of the sixth part of the microstrip line is 1.68 mm.

8. A microwave filter, characterized in that, The microwave filter includes an input feed line, an output feed line, and a coupling structure; the coupling structure is obtained by coupling at least two microstrip resonators with a dual-spin-in / spin-out structure as described in any one of claims 1-7. Both the input feed line and the output feed line are connected to the coupling structure.

9. The microwave filter according to claim 8, characterized in that, If the coupling structure adopts an asymmetric double-spin-in / spin-out microstrip resonator, the spacing between each pair of microstrip resonators is 1 mm; the asymmetric double-spin-in / spin-out microstrip resonator is a microstrip resonator in which the length of the second part of the microstrip line of the U-shaped structure is different from the length of the fifth part of the microstrip line.

10. The microwave filter according to claim 8, characterized in that, If the coupling structure uses a microstrip resonator with the same length of the second part of the U-shaped microstrip line as the fifth part of the microstrip line, then the spacing between every two microstrip resonators is 1.4 mm.

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