Cavity filter

Abstract

The utility model discloses a cavity filter, which comprises a cavity, a cover body, a circuit board and a screw rod, and is characterized in that the cavity is internally provided with a resonant cavity, and the resonant cavity is provided with a resonant column corresponding to an opening; the cover body is mounted on the cavity and is provided with a screw hole; the circuit board is arranged on the resonant column and located in the resonant cavity or completely covers an opening corresponding to the resonant cavity, the circuit board comprises a conductive through hole penetrating through the circuit board and resonant patterns arranged on the two opposite sides of the circuit board, and the resonant patterns arranged on the two opposite sides of the circuit board are correspondingly connected through the conductive through hole to form a resonator; the resonator is arranged corresponding to the resonant cavity; and the screw rod penetrates through the screw rod hole and is arranged corresponding to the resonator. Therefore, the cavity filter with an efficient construction frame is formed by integrating the resonators configured on the circuit board and matching with the cavity, the cover body and the screw rod, and the power, the frequency, the insertion loss and the coupling required by the cavity filter can realize the optimal electrical performance in a limited space, so that the cavity filter is suitable for various topological structures.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a cavity filter. Background Art

[0002] In wireless communication systems, interference from the external environment can seriously affect the performance of the entire system. Therefore, cavity filters used to select communication signals and filter out clutter or interference signals become indispensable components.

[0003] However, different communication environments require cavity filters of different specifications. The materials and sizes of the resonators required for cavity filters of different specifications cannot be unified, and may require the use of multiple processing methods (such as turning, milling, CNC processing, stretching, cold heading, etc.), resulting in high processing costs and the problem of not being able to produce modular products in large quantities. In addition, cavity filters of different specifications also have the problem of relatively unstable part sizes and complex assembly. Utility Model Content

[0004] The embodiment of the present application provides a cavity filter, which can solve the problems in the prior art that cavity filters suitable for different communication environments cannot be produced in a modularized manner in large quantities due to different specifications, and the size of parts is relatively unstable and the assembly is complicated.

[0005] In order to solve the above technical problems, this application is implemented as follows:

[0006] The present application provides a cavity filter, which includes: a cavity, a cover, a circuit board and a screw, wherein the cavity has a resonant cavity, the resonant cavity is provided with a resonant column and a corresponding opening; the cover is installed on the cavity and is provided with a screw hole; the circuit board is arranged on the resonant column and is located in the resonant cavity or completely covers the opening corresponding to the resonant cavity, the circuit board includes a conductive through hole passing through the circuit board and a resonant pattern arranged on opposite sides of the circuit board, the resonant patterns arranged on opposite sides of the circuit board are connected correspondingly through the conductive through holes to form a resonator, and the resonator is arranged corresponding to the resonant cavity; the screw passes through the screw hole and is arranged corresponding to the resonator.

[0007] In the embodiment of the present application, a cavity filter with an efficient construction framework is formed by integrating a resonator configured on a circuit board, with a cavity, a cover and a screw, wherein the cavity and the cover can be made of alloy materials, and their surfaces can be metal-plated; the resonant pattern constituting the resonator can be integrated and configured on the circuit board by sinking aluminum, copper, silver or gold; the screw can be made of alloy materials, and its surface can be passivated, metal-plated and waxed. Therefore, the power, frequency, insertion loss and coupling required by the cavity filter can also achieve optimal electrical performance in a limited space, so that it is suitable for various topological structures. At the same time, it can also solve the problems in the prior art that cavity filters suitable for different communication environments cannot be mass-produced modularly due to different specifications, the size of parts is relatively unstable and the assembly is complicated. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are configured to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0009] Figure 1 It is a three-dimensional schematic diagram of a first embodiment of a cavity filter according to the present application;

[0010] Figure 2 for Figure 1 A cross-sectional schematic diagram of a cavity filter;

[0011] Figure 3 is a three-dimensional schematic diagram of a second embodiment of a cavity filter according to the present application;

[0012] Figure 4 for Figure 3 A cross-sectional schematic diagram of a cavity filter;

[0013] Figure 5 It is a three-dimensional schematic diagram of a third embodiment of a cavity filter according to the present application;

[0014] Figure 6 for Figure 5 A cross-sectional schematic diagram of a cavity filter;

[0015] Figure 7 is a three-dimensional schematic diagram of a fourth embodiment of a cavity filter according to the present application;

[0016] Figure 8 for Figure 7 An exploded schematic diagram of the cavity filter;

[0017] Fig. 9 for Figure 7 A top view of a circuit board;

[0018] Fig.10for Figure 7 A bottom view of a circuit board;

[0019] Fig.11 for Fig. 9 A schematic cross-sectional view of the AA line segment shown;

[0020] Fig.12 A schematic cross-sectional view of an embodiment of a circuit board of the present application; and

[0021] Fig.13 for Figure 8 Simulation characteristic curves of the transmission coefficient and reflection coefficient of the cavity filter. DETAILED DESCRIPTION

[0022] The following will be used in conjunction with the accompanying drawings to illustrate the embodiments of the present utility model. In these drawings, the same reference numerals represent the same or similar components or method flows.

[0023] It must be understood that the words "comprise", "include", etc. used in this specification are configured to indicate the existence of specific technical features, values, method steps, job processing and / or components, but do not exclude the addition of more technical features, values, method steps, job processing, components, or any combination of the above.

[0024] It should be understood that when a component is described as being "connected" or "coupled" to another component, it may be directly connected or coupled to the other component, and intermediate components may be present. Conversely, when a component is described as being "directly connected" or "directly coupled" to another component, there are no intermediate components.

[0025] See also Figure 1 and Figure 2 , Figure 1 is a three-dimensional schematic diagram of a first embodiment of a cavity filter according to the present application, Figure 2 for Figure 1 A cross-sectional diagram of a cavity filter. Figure 1 and Figure 2As shown, the cavity filter 1 includes: a cavity 11, a cover 12, a circuit board 13 and a screw 14. The cavity 11 has a resonant cavity 111, and the resonant cavity 111 is provided with a resonant column 1111 and a corresponding opening 1112; the cover 12 is installed on the cavity 11 and is provided with a screw hole 121; the circuit board 13 is arranged on the resonant column 1111 and is located in the resonant cavity 111, the circuit board 13 includes a conductive through hole 131 passing through the circuit board 13 and a resonant pattern 132 arranged on opposite sides of the circuit board 13, the resonant patterns 132 arranged on opposite sides of the circuit board 13 are connected correspondingly through the conductive through hole 131 to form a resonator 133, and the resonator 133 is arranged corresponding to the resonant cavity 111; the screw 14 passes through the screw hole 121 and is arranged corresponding to the resonator 133 (that is, the screw 14 is a tuning screw, and the length of the screw 14 passing through the screw hole 121 is adjustable for adjusting the resonant frequency).

[0026] The resonant patterns 132 disposed on opposite sides of the circuit board 13 may be connected correspondingly through a plurality of conductive through holes 131. It should be noted that in order to avoid Figure 2 The drawing is too complicated, and only two conductive through holes 131 are drawn as representatives; the cavity 11 and the cover 12 only need to have metal surfaces. Therefore, various materials (for example, alloy materials) can be used for modular production in large quantities, and the surface can be plated with metal (for example, silver, copper or gold); the resonant patterns 132 arranged on the opposite sides of the circuit board 13 can be patterned and integrated on the circuit board 13 by aluminum, copper, silver or gold, which is conducive to large-scale modular production and does not have the problem of complex assembly; the shapes of the resonant patterns 132 arranged on the opposite sides of the circuit board 13 and correspondingly connected can be the same or different, and the shapes of the resonant patterns 132 arranged on the opposite sides of the circuit board 13 can be circular, square, triangular, polygonal or other irregular shapes, and the actual shape can be designed according to the requirements of the cavity filter 1.

[0027] In this embodiment, the number of the resonant cavity 111, the resonant pattern 132 arranged on opposite sides of the circuit board 13, the resonator 133, the screw 14 and the screw hole 121 can be one each to form a single-cavity filter; the height H1 of the resonant column 1111 can be lower than the height H2 of the side wall 1113 of the resonant cavity 111, and the circuit board 13 is located in the resonant cavity 111 and welded to the resonant column 1111; the screw 14 can be a self-locking screw; the shapes of the resonant patterns 132 arranged on opposite sides of the circuit board 13 and correspondingly connected can be the same; but this embodiment is not used to limit the present application.

[0028] For example, see Figure 3 and Figure 4 , Figure 3 is a three-dimensional schematic diagram of a second embodiment of a cavity filter according to the present application, Figure 4 for Figure 3A cross-sectional diagram of a cavity filter. Figure 3 and Figure 4 Examples and Figure 1 and Figure 2 The difference between the embodiments is that Figure 3 and Figure 4 The screw 14 of the embodiment may be a common screw (ie, a conventional screw); see Figure 5 and Figure 6 , Figure 5 is a three-dimensional schematic diagram of a third embodiment of a cavity filter according to the present application, Figure 6 for Figure 5 A cross-sectional diagram of a cavity filter. Figure 5 and Figure 6 Examples and Figure 1 and Figure 2 The difference between the embodiments is that Figure 5 and Figure 6 The circuit board 13 completely covers the opening 1112, the cover body 12 is provided with a cavity 122, the side wall 1221 of the cavity 122 is connected to the circuit board 13, and the circuit board 13 is arranged between the cavity 11 and the cover body 12, wherein, Figure 5 and Figure 6 The sidewalls 1221 of the cavity 11 and the recessed cavity 122 can be soldered to the two opposite sides of the circuit board 13 facing the cavity 11 and the cover 12 through solder paste, and the circuit board 13 can be selectively soldered to the resonant column 1111 through solder paste.

[0029] See also Figures 7 to 11 , Figure 7 is a three-dimensional schematic diagram of a fourth embodiment of a cavity filter according to the present application, Figure 8 for Figure 7 Exploded diagram of the cavity filter. Fig. 9 for Figure 7 A top view of the circuit board. Fig.10 for Figure 7 Bottom view of the circuit board, Fig.11 for Fig. 9 The cross-sectional diagram of the AA line segment is shown in FIG. Figures 7 to 11 As shown, the cavity filter 2 includes: a cavity 21, a cover 22, a circuit board 23 and a plurality of screws 24 (for example, twenty-one screws 24), the cavity 21 has a plurality of resonant cavities 211 (for example, nine resonant cavities 211), each resonant cavity 211 is provided with a resonant column 2111 and a corresponding opening 2112, and the heights of all the resonant columns 2111 are consistent; the cover 22 is mounted on the cavity 21 and is provided with a plurality of screw holes 221 (for example, twenty-one screw holes 221) and a concave cavity, the side wall of the concave cavity is connected to the circuit board 23, and the circuit board 23 is arranged between the cavity 21 and the cover 22 (similar to Figure 2As shown); the circuit board 23 is arranged on each resonant column 2111 and completely covers the opening 2112 corresponding to each resonant cavity 211. The circuit board 23 includes a plurality of conductive through holes 231 penetrating the circuit board 23, a plurality of resonant patterns 232 (for example, nine resonant patterns 232) arranged on opposite sides of the circuit board 23, and a grounding frame 234 arranged on opposite sides of the circuit board 23. The grounding frame 234 surrounds the plurality of resonant patterns 232 located on the same side. The plurality of resonant patterns 232 arranged on opposite sides of the circuit board 23 and corresponding to each other are connected through a plurality of conductive through holes 231 to form a plurality of resonators 233 (for example, nine resonators 233). The plurality of resonators 233 are arranged corresponding to the plurality of resonant cavities 211 (that is, the number of resonant cavities 211 and resonator 233 is the same and they are arranged one to one). Adjacent resonant cavities 211 are connected to each other. The grounding frames 234 arranged on opposite sides of the circuit board 23 and corresponding to each other are connected through a plurality of conductive through holes 231 (as shown). Figures 8 to 10 ; a portion of the plurality of screw rods 24 (for example, nine screw rods 24) passes through the corresponding screw rod holes 221 and is disposed opposite to the corresponding resonator 233 to adjust the resonant frequency; another portion of the plurality of screw rods 24 (for example, ten screw rods 24) passes through the corresponding screw rod holes 221 and the corresponding openings 235 on the circuit board 23, and extends into the corresponding resonant cavity 211 to adjust the coupling amount; another portion of the plurality of screw rods 24 (for example, two screw rods 24) passes through the screw rod holes 221 and is disposed opposite to the corresponding cross-coupling patterns 236 to adjust the coupling amount (the description of the cross-coupling patterns 236 will be described in detail later); the lengths of all the screw rods 24 passing through the corresponding screw rod holes 221 are adjustable.

[0030] The number and configuration positions of the resonant cavity 211, the screw 24, the screw hole 221, the conductive through hole 231, the resonator 233 and the opening 235 can be adjusted according to the signal transmission path of the cavity filter 2 and other requirements. Figures 8 to 11 The drawing is too complex and is omitted. Figures 8 to 10 The plurality of conductive through holes 231 correspondingly connect the plurality of resonant patterns 232 disposed on opposite sides of the circuit board 23, Fig.11 Only four conductive through holes 231 are drawn as representatives; in this embodiment, the shapes of the multiple resonant patterns 232 arranged on the opposite sides of the circuit board 23 and correspondingly connected may be different, and the shapes and configuration positions of the grounding frames 234 arranged on the opposite sides of the circuit board 23 and correspondingly connected may be the same; in this embodiment, the multiple resonant patterns 232 are integrated on the same circuit board 23, but this embodiment is not used to limit the present application. For example, in other embodiments, the multiple resonant patterns 232 may be arranged on multiple circuit boards that are independent of each other, located in different resonant cavities 211 and soldered on corresponding resonant columns 1111.

[0031] In one embodiment, the periphery of the cavity 21 is provided with a plurality of threaded grooves 212, the periphery of the cover 22 is provided with a plurality of connecting ears 223 provided with threaded holes 222, and the periphery of the circuit board 23 is provided with a plurality of positioning ears 238 provided with positioning holes 237. The cavity filter 2 may also include a plurality of screws 25, and the plurality of connecting ears 223 provided with threaded holes 222, the plurality of positioning ears 238 provided with positioning holes 237, and the plurality of threaded grooves 212 are connected by a plurality of screws 25 to lock the circuit board 23 between the cavity 21 and the cover 22. Therefore, when the cavity filter 2 fails and needs to repair or replace the circuit board 23, it can be easily disassembled and repeatedly assembled for use. Among them, the number and configuration positions of the threaded grooves 212, the connecting ears 223, the positioning ears 238, and the screws 25 can be adjusted according to actual needs.

[0032] In one embodiment, the cavity 21 and the sidewalls of the concave cavity may be soldered to the ground frames 234 disposed on opposite sides of the circuit board 23 by solder paste.

[0033] In one embodiment, the circuit board 23 may further include a cross-coupling pattern 236 (i.e., a flying rod) disposed on opposite sides of the circuit board 23. The cross-coupling patterns 236 disposed on opposite sides of the circuit board 23 are correspondingly connected through a plurality of conductive through-holes 231, and the two resonators 233 located on both sides of the cross-coupling pattern 236 generate capacitive cross-coupling. Among them, the number, shape, and configuration position of the cross-coupling pattern 236 may be designed according to the actual needs of the cavity filter 2. Therefore, the cross-coupling pattern 236 may be patterned and integrated on the circuit board 23 by using aluminum, copper, silver, or gold, which is conducive to large-scale modular production and does not involve the problem of complex assembly. It should be noted that in this embodiment, the shapes of the cross-coupling patterns 236 disposed on opposite sides of the circuit board 23 and correspondingly connected may be different; for example, Fig. 9 In the top view of FIG. 1 , the cross-coupling pattern 236 located on the same side is spaced apart from the resonant pattern 232 adjacent to the two ends thereof that generates capacitive cross-coupling. Fig.10 The cross-coupling pattern 236 located on the same side in the bottom view of FIG. 1 is integrated with the resonant pattern 232 adjacent to both ends thereof for generating capacitive cross-coupling.

[0034] In one embodiment, the cavity filter 2 may further include an input connector 26 and an output connector 27, which are disposed in the cavity 21 or the cover 22 and are respectively coupled to different resonators 233. Figures 7 to 11As can be seen from the figure, the input connector 26 and the output connector 27 are arranged on the outer bottom surface of the cavity 21, and two transmission strip lines 239 are also arranged on the side of the circuit board 23 facing the input connector 26 and the output connector 27. One end of each transmission strip line 239 is provided with an opening 235, and the other end of each transmission strip line 239 is connected to a resonant pattern 232. The connecting rod 261 of the input connector 26 and the connecting rod 271 of the output connector 27 pass through different openings 235 respectively and couple different resonators 233 through the transmission strip lines 239. Among them, the input connector 26 is used to input signals to the cavity filter 2, and the output connector 27 is used to output signals filtered by the cavity filter 2.

[0035] In one embodiment, the shapes of the resonant patterns 232 disposed on two opposite sides of the circuit board 23 and connected correspondingly may be the same or different.

[0036] In one embodiment, the resonant patterns 232 disposed on opposite sides of the circuit board 23 may have a circular, square, triangular, polygonal or other irregular shapes.

[0037] In one embodiment, the resonant patterns 232 disposed on opposite sides of the circuit board 23 are correspondingly connected through a plurality of conductive through holes 231. The greater the density of the conductive through holes 231 connecting the resonant patterns 232, the greater the quality factor (Q value) of the resonator 233. Specifically, the denser the conductive through holes 231 connecting the resonant patterns 232, the more obvious the improvement of the Q value. However, when the spacing between adjacent conductive through holes 231 is less than or equal to one eighth of the wavelength of the resonant frequency of the cavity filter 2, the influence on the Q value will gradually decrease.

[0038] In one embodiment, the circuit board 23 can be any one of a single-layer board, a double-layer board, and a multi-layer board. The more layers the circuit board 23 has, the smaller the quality factor (Q value) of the resonator 233. In other words, the more layers the circuit board 23 has, the worse the Q value of the resonator 233 will be.

[0039] In one embodiment, the circuit board 23 may be a multilayer board and may include a plurality of wiring layers 31 and a plurality of dielectric layers 32 that are stacked alternately. The plurality of dielectric layers 32 may be made of the same material or different materials. The plurality of wiring layers 31 are electrically connected to the plurality of resonant patterns 232 and the ground frame 234 disposed on opposite sides of the circuit board 23 through a plurality of conductive through holes 33 that penetrate the dielectric layer 32 (e.g., Fig.12 As shown, Fig.12 This is a cross-sectional diagram of an embodiment of a circuit board of the present application. It should be noted that in order to avoid Fig.12 The drawing is too complex, and only four conductive vias 33 are drawn as a representative).

[0040] In one embodiment, the more the number of the wiring layers 31 is, the greater the quality factor (Q value) of the resonator 233 is.

[0041] See also Figure 8 and Fig.13 , Fig.13 for Figure 8 The simulation characteristic curve of the transmission coefficient (S21) and reflection coefficient (S11) of the cavity filter, where: Fig.13 The horizontal axis is frequency, and the unit is Hertz (Hz); Fig.13 The left vertical axis is the transmission coefficient (S21), in decibels (dB); Fig.13 The right vertical axis is the reflection coefficient (S11), in decibels (dB); Fig.13 The solid line is the simulation characteristic curve of the reflection coefficient; Fig.13 The dotted line is the simulation characteristic curve of the transmission coefficient. Figure 8 and Fig.13 As shown, the cavity filter 2 uses nine resonators 233 / nine resonant cavities 211, and loads four transmission poles (at the low end (i.e. Fig.13 The left side of the Fig.13 Two zero points are generated on the right side of the cavity filter 2), which satisfies the passband low loss characteristics of the cavity filter 2 and presents the characteristics of a bandpass filter.

[0042] In summary, by integrating the resonator configured on the circuit board, matching the cavity, cover and screw, a cavity filter with an efficient construction frame is formed, wherein the cavity and cover can be made of alloy material, and their surfaces can be metal-plated; the resonant pattern constituting the resonator can be integrated on the circuit board by aluminum, copper, silver or gold; the screw can be made of alloy material, and its surface can be passivated, metal-plated and waxed. Therefore, the power, frequency, insertion loss and coupling required by the cavity filter can also achieve optimal electrical performance in a limited space, so that it is suitable for various topological structures. At the same time, it can also solve the problems in the prior art that cavity filters suitable for different communication environments cannot be mass-produced modularly due to different specifications, the size of parts is relatively unstable and the assembly is complicated. In addition, the cross-coupling pattern (i.e., flying rod) can also be patterned and integrated on the circuit board.

[0043] Although the present invention is described using the above embodiments, it should be noted that these descriptions are not configured to limit the present invention. On the contrary, the present invention covers obvious modifications and similar arrangements that are obvious to those skilled in the art. Therefore, the scope of the claims should be interpreted in the broadest way to include all obvious modifications and similar arrangements.

Claims

1. A cavity filter, characterized in that: include: A cavity, wherein a resonant cavity is provided in the cavity, and the resonant cavity is provided with a resonant column and a corresponding opening; A cover body, mounted on the cavity and provided with a screw hole; A circuit board is arranged on the resonant column and is located in the resonant cavity or completely covers the opening corresponding to the resonant cavity, the circuit board includes a conductive through hole penetrating the circuit board and resonant patterns arranged on opposite sides of the circuit board, the resonant patterns arranged on opposite sides of the circuit board are connected correspondingly through the conductive through holes to form a resonator, and the resonator is arranged corresponding to the resonant cavity; as well as A screw rod passes through the screw rod hole and is arranged corresponding to the resonator.

2. The cavity filter according to claim 1, characterized in that: The height of the resonant column is lower than the height of the side wall of the resonant cavity. The circuit board is located in the resonant cavity and is welded on the resonant column.

3. The cavity filter according to claim 1, characterized in that: The circuit board completely covers the opening, the cover body is provided with a concave cavity, the side wall of the concave cavity is connected to the circuit board, and the circuit board is arranged between the cavity and the cover body.

4. The cavity filter according to claim 3, characterized in that: The number of the resonant cavities, the conductive through holes and the resonant patterns arranged on opposite sides of the circuit board is multiple, the number of the resonant cavities is the same as the number of the resonators and they are arranged one-to-one, adjacent resonant cavities are connected to each other, the circuit board completely covers the opening corresponding to each resonant cavity, and the circuit board also includes a grounding frame arranged on opposite sides of the circuit board, the grounding frames arranged on opposite sides of the circuit board are correspondingly connected through multiple conductive through holes, and the grounding frame surrounds the multiple resonant patterns located on the same side.

5. The cavity filter according to claim 4, characterized in that: The number of the screw holes and the screws is multiple and they are arranged one to one, a part of the multiple screws passes through the corresponding screw holes and is arranged opposite to the corresponding resonator; another part of the multiple screws passes through the corresponding screw holes and the corresponding openings on the circuit board and extends into the corresponding resonant cavity.

6. The cavity filter according to claim 4, characterized in that: The periphery of the cavity is provided with a plurality of threaded grooves, the periphery of the cover body is provided with a plurality of connecting ears provided with threaded holes, the periphery of the circuit board is provided with a plurality of positioning ears provided with positioning holes, and the cavity filter further comprises a plurality of screws, and the plurality of connecting ears provided with threaded holes, the plurality of positioning ears provided with positioning holes and the plurality of threaded grooves are connected by the plurality of screws to lock the circuit board between the cavity and the cover body.

7. The cavity filter according to claim 4, characterized in that: The cavity and the side walls of the concave cavity are welded to the grounding frames arranged on opposite sides of the circuit board through solder paste.

8. The cavity filter according to claim 4, characterized in that: The circuit board also includes cross-coupling patterns arranged on opposite sides of the circuit board. The cross-coupling patterns arranged on opposite sides of the circuit board are correspondingly connected through a plurality of conductive through holes, and the two resonators located on both sides of the cross-coupling pattern generate capacitive cross-coupling.

9. The cavity filter according to claim 4, characterized in that: It also includes an input connector and an output connector, which are arranged in the cavity or the cover and are respectively coupled to different resonators.

10. The cavity filter according to claim 4, characterized in that: The circuit board is any one of a single-layer board, a double-layer board, and a multi-layer board. The more layers the circuit board has, the smaller the quality factor of the resonator.

11. The cavity filter according to claim 4, characterized in that: The circuit board includes a plurality of wiring layers and a plurality of dielectric layers which are stacked alternately, and the plurality of dielectric layers are made of the same material or different materials.

12. The cavity filter according to claim 11, characterized in that: The greater the number of the plurality of wiring layers, the greater the quality factor of the resonator.

13. The cavity filter according to claim 4, characterized in that: The resonant patterns arranged on opposite sides of the circuit board are correspondingly connected through a plurality of the conductive through holes. The greater the density of the conductive through holes connecting the resonant patterns, the greater the quality factor of the resonator.

14. The cavity filter according to claim 1, characterized in that: The resonant patterns disposed on two opposite sides of the circuit board and connected correspondingly may have the same or different shapes.

15. The cavity filter according to claim 1, characterized in that: The resonant patterns disposed on opposite sides of the circuit board may have shapes including a circle, a square, a triangle, or a polygon.

16. The cavity filter according to claim 1, characterized in that: The screw is a self-locking screw.

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