Cavity filter

Abstract

The application discloses a cavity filter, comprising a shell, an input resonator and an output resonator; the shell has a containing cavity and is provided with an input through hole and an output through hole which are communicated with the containing cavity; the input resonator and the output resonator are located in the containing cavity and are fixed to the shell; the input resonator comprises a first sheet resonant body, an input end and a first branch which are extended outward from one side of the first sheet resonant body, the input end and the first branch are connected with each other or are spaced apart from each other, and the input end extends out of the shell through the input through hole; the output resonator comprises a second sheet resonant body and an output end which is extended outward from one side of the second sheet resonant body, the output end extends out of the shell through the output through hole, and the first branch is used for generating a resonant peak. Therefore, the cavity filter has the function of suppressing far-end harmonics and can meet the requirements of miniaturization and light weight.

Description

[0001] This application is a divisional application of Chinese patent application No. 202210840530.1, filed on July 18, 2022, entitled "Cavity Filter". Technical Field

[0002] This application relates to the technical field of filters, and more particularly to a cavity filter. Background Technology

[0003] Cavity filters used to select communication signal frequencies and filter out noise or interference signals outside the communication signal frequencies typically include a cavity, a resonant rod, a cover plate, and a tuning screw. The cover plate and the cavity form a resonant cavity. The resonant rod is located at the bottom of the cavity and is cylindrical. The cover plate, in conjunction with the tuning screw, adjusts the coupling frequency of the cavity filter.

[0004] Because cavity filters generate harmonics at integer multiples of the fundamental frequency, harmonic suppression of cavity filters has always been a concern for those skilled in the art. Existing cavity filters generally use cascaded low-pass filters (e.g., candied hawthorn low-pass filters, sheet-like low-pass filters) to suppress far-end harmonics. However, cavity filters that suppress far-end harmonics by adding an extra low-pass filter have the following disadvantages: (1) more cavity materials, more complex assembly, and higher cost; (2) the low-pass filter requires space in the cavity filter, making it impossible for the cavity filter to achieve optimal performance; (3) the addition of an extra low-pass filter increases the insertion loss of the cavity filter; and (4) it is impossible to design the cavity filter to be smaller and lighter.

[0005] Therefore, how to provide a solution to the above-mentioned technical problems is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] This application provides a cavity filter that can solve the problems of existing cavity filters that suppress far-end harmonics by adding a low-pass filter, such as high cost, inability to achieve optimal performance, increased insertion loss, and inability to be lightweight and miniaturized due to the additional low-pass filter.

[0007] To solve the above-mentioned technical problems, this application is implemented as follows:

[0008] This application provides a cavity filter. The cavity filter includes: a housing, an input resonator, and an output resonator; the housing has a cavity and is provided with an input through-hole and an output through-hole communicating with the cavity; the input resonator and the output resonator are located in the cavity and fixed to the housing; the input resonator includes a first sheet-like resonant body, an input end extending outward from one side of the first sheet-like resonant body, and a first spur, the input end and the first spur are connected to each other or spaced apart from each other, and the input end extends out of the housing through the input through-hole; the output resonator includes a second sheet-like resonant body and an output end extending outward from one side of the second sheet-like resonant body, the output end extends out of the housing through the output through-hole, and the first spur is used to generate a resonance peak.

[0009] In the embodiments of this application, by setting the first stub of the input resonator and using the first stub to generate the resonance peak, the cavity filter has the function of suppressing far-end harmonics. Moreover, due to its simple structure and the absence of a low-pass filter, the cavity filter reduces material costs, simplifies the manufacturing process, lowers costs, and provides good performance stability and consistency. Therefore, it can meet the requirements of miniaturization and lightweighting. Attached Figure Description

[0010] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0011] Figure 1 An exploded view of a first embodiment of the cavity filter according to this application;

[0012] Figure 2 for Figure 1 A diagram of the cavity filter combination;

[0013] Figure 3 for Figure 1 A bottom view of the cavity filter;

[0014] Figure 4 for Figure 1 A schematic diagram of the input resonator;

[0015] Figure 5 for Figure 1 A schematic diagram of the output resonator;

[0016] Figure 6 An exploded view of a second embodiment of the cavity filter according to this application;

[0017] Figure 7 for Figure 6 A diagram of the cavity filter combination;

[0018] Figure 8 for Figure 6Side view of the cavity filter;

[0019] Figure 9 for Figure 6 A schematic diagram of the input resonator;

[0020] Figure 10 for Figure 6 A schematic diagram of the output resonator;

[0021] Figure 11 An exploded view of a third embodiment of the cavity filter according to this application;

[0022] Figure 12 for Figure 11 A diagram of the cavity filter combination;

[0023] Figure 13 for Figure 11 A bottom view of the cavity filter;

[0024] Figure 14 for Figure 11 A schematic diagram of the input resonator;

[0025] Figure 15 for Figure 11 A schematic diagram of the output resonator;

[0026] Figure 16 for Figure 11 A schematic diagram of the structure of the intermediate resonator;

[0027] Figure 17 for Figure 12 A cross-sectional view along line segment AA';

[0028] Figure 18 for Figure 1 Simulation curves of S-parameters for a cavity filter without the first and second stubs; and

[0029] Figure 19 for Figure 1 The simulation curves of the S-parameters of the cavity filter. Detailed Implementation

[0030] The embodiments of the present invention will be described below with reference to the accompanying drawings. In these drawings, the same reference numerals denote the same or similar components or method flows.

[0031] It must be understood that the use of terms such as "comprising" or "including" in this specification is intended to indicate the presence of specific technical features, values, method steps, work processes and / or components, but does not preclude the addition of more technical features, values, method steps, work processes, components, or any combination thereof.

[0032] It is important to understand that when a component is described as "connected" or "coupled" to another component, it can be a direct connection or coupling to other components, and there may be intermediate components. Conversely, when a component is described as "directly connected" or "directly coupled" to another component, there are no intermediate components.

[0033] Please see Figures 1 to 3 , Figure 1 An exploded view of a first embodiment of the cavity filter according to this application. Figure 2 for Figure 1 A diagram of the cavity filter combination. Figure 3 for Figure 1 A bottom view of the cavity filter. (See attached image.) Figures 1 to 3 As shown, the cavity filter 100 includes a housing 110, an input resonator 120, and an output resonator 130. The housing 110 may include a base plate 117, a side wall 118, and a cover plate 119. It should be noted that, to illustrate the internal assembly of the housing 110 of the cavity filter 100, [details omitted]. Figure 2 The cover plate 119 of the shell 110 is omitted from the drawing.

[0034] The housing 110 has a receiving cavity 112 and is provided with an input through hole 114 and an output through hole 116 communicating with the receiving cavity 112. The input resonator 120 and the output resonator 130 are located in the receiving cavity 112 and fixed to the housing 110. Specifically, the side wall portion 118 is connected to the bottom plate portion 117 around it. The side wall portion 118 and the bottom plate portion 117 form the receiving cavity 112 and the opening 90. One side of the cover plate portion 119 covers and is fixed to the opening 90. The input resonator 120 and the output resonator 130 are fixed to the bottom plate portion 117. The input through hole 114 and the output through hole 116 are provided in the bottom plate portion 117.

[0035] Please see Figures 1 to 5 , Figure 4 for Figure 1 A schematic diagram of the input resonator. Figure 5 for Figure 1A schematic diagram of the output resonator is shown. In this embodiment, the input resonator 120 includes a first sheet-like resonant body 122, an input terminal 124 extending outward from one side of the first sheet-like resonant body 122, and a first branch 126. The first branch 126 extends outward from the same side of the first sheet-like resonant body 122 as the input terminal 124, and / or the first branch 126 extends outward from the input terminal 124 (i.e., the input terminal 124 and the first branch 126 are connected to or spaced apart from each other). The input terminal 124 passes through an input through-hole 114. The output resonator 130 extends out of the housing 110 and includes a second sheet-like resonant body 132, an output terminal 134 extending outward from one side of the second sheet-like resonant body 132, and a second branch 136, wherein the second branch 136 extends outward from the same side of the output terminal 134 on the second sheet-like resonant body 132 and / or the second branch 136 extends outward from the output terminal 134 (i.e., the output terminal 134 and the second branch 136 are connected to each other or spaced apart from each other), and the output terminal 134 extends out of the housing 110 through the output through hole 116.

[0036] Therefore, the cavity filter 100 can extend out of the housing 110 through the input terminal 124 of the input resonator 120 via the input through-hole 114 and the output terminal 134 of the output resonator 130 via the output through-hole 116, thus realizing a simple structure of the filter port. Furthermore, since the input through-hole 114 and the output through-hole 116 are located on the bottom plate portion 117 of the housing 110, the input terminal 124 and the output terminal 134 can be directly surface-mounted to an external circuit board.

[0037] In this embodiment, the lengths of both the first branch 126 and the second branch 136 are one-quarter wavelengths of the resonant frequency of the cavity filter 100. Since the first branch 126 extends outward from one side of the first sheet-like resonant body 122 and / or extends outward from the input end 124 (i.e., the first branch 126 and the first sheet-like resonant body 122 are integrally formed), and the second branch 136 extends outward from one side of the second sheet-like resonant body 132 and / or extends outward from the output end 134 (i.e., the second branch 136 and the second sheet-like resonant body 132 are integrally formed), and the lengths of both the first branch 126 and the second branch 136 are one-quarter wavelengths of the resonant frequency of the cavity filter 100, the cavity filter 100 has the function of suppressing far-end harmonics.

[0038] In this embodiment, after an external electrical signal enters the cavity filter 100, the signal is transmitted from the input terminal 124 of the input resonator 120 to the output terminal 134 of the output resonator 130. Specifically, after the external electrical signal enters the cavity filter 100 from the input terminal 124, it first passes through the first stub 126 of the input resonator 120, then through the first sheet-like resonant body 122, and then through coupling to the second sheet-like resonant body 132, then to the second stub 136, and finally output from the output terminal 134 of the output resonator 130. Since the first stub 126 and the second stub 136 can generate resonance peaks, the cavity filter 100 can suppress far-end harmonics.

[0039] The number of first branches 126 and second branches 136 can be multiple. It should be noted that the more first branches 126 and second branches 136 there are, the better the harmonic suppression effect of the cavity filter 100. The actual number of first branches 126 and second branches 136 can be adjusted according to the spatial size of the cavity filter 100 (i.e., the spatial size of the accommodating cavity 112). In this embodiment, the number of first branches 126 can be two (i.e., first branches 126a and 126b), and the number of second branches 136 can be three (i.e., second branches 136a, 136b, and 136c). The first branches 126a, 126b, 136a, 136b, and 136c generate five resonant peaks to suppress the far-end harmonics of the cavity filter 100.

[0040] In addition, the shapes of the first branch 126 and the second branch 136 can be arbitrary, but their lengths must be one-quarter of the resonant frequency of the cavity filter 100 in order to achieve the effect of suppressing the far-end harmonics of the cavity filter 100.

[0041] In this embodiment, the first branch 126a includes a first extension segment 81 extending outward from one side of the first sheet-like resonant body 122 (i.e., the first branch 126a and the input terminal 124 are spaced apart from each other), the first branch 126b includes a second extension segment 82 extending outward from the input terminal 124 and a third extension segment 83 extending from the end of the second extension segment 82 away from the input terminal 124 (i.e., the first branch 126b and the input terminal 124 are connected to each other), and the second branch 136a includes a first extension segment 81 extending outward from one side of the second sheet-like resonant body 132. The extended fourth extension 84a (i.e., the second branch 136a is spaced apart from the output terminal 134), the second branch 136b includes a fourth extension 84b extending outward from one side of the second sheet-like resonant body 132 (i.e., the second branch 136b is spaced apart from the output terminal 134), and the second branch 136c includes a fifth extension 85 extending outward from the output terminal 134 and a sixth extension 86 extending from the end of the fifth extension 85 away from the output terminal 134 (i.e., the second branch 136c is connected to the output terminal 134). The lengths of the first extension 81, the second extension 82, and the third extension 83, the fourth extension 84a, the fourth extension 84b, and the fifth extension 85 and the sixth extension 86 are all one-quarter wavelength of the resonant frequency of the cavity filter 100.

[0042] In this embodiment, the input resonator 120 and the output resonator 130 are sheets with metal surfaces or metal sheets. Therefore, the cavity filter 100 can achieve capacitive coupling without a physical capacitive structure, thereby achieving a low-end transmission zero. When the input resonator 120 and the output resonator 130 are metal sheets, they can be directly cut from metal plates; when the input resonator 120 and the output resonator 130 are sheets with metal surfaces, they can be injection molded from plastic material and then electroplated; the thickness of the input resonator 120 and the output resonator 130 can be, but is not limited to, 0.5 mm to 1 mm.

[0043] In one embodiment, the first sheet-like resonant body 122 and the second sheet-like resonant body 132 each include a resonant rod 50. Each resonant rod 50 includes an upright section 52 and an extension section 54. The extension section 54 extends outward from one side of the upright section 52. The input end 124 and the output end 134 extend outward from the opposite side of the upright section 52 of the first sheet-like resonant body 122 and the second sheet-like resonant body 132 relative to the extension section 54, respectively. A first branch 126 extends outward from the upright section 52 of the first sheet-like resonant body 122 or from the input end 124. A second branch 136 extends outward from the upright section 52 of the second sheet-like resonant body 132 or from the output end 134. In one embodiment, the first extension section 81 of the first branch 126a extends outward from one side of the upright section 52 of the first sheet-like resonant body 122; and / or the second extension section 82 of the first branch 126b extends outward from the input end 124. In one embodiment, the fourth extension 84a of the second branch 136a extends outward from one side of the upright section 52 of the second sheet-like resonant body 132; and / or the fifth extension 85 of the second branch 136b extends outward from the output end 134.

[0044] In one embodiment, the first sheet-like resonant body 122 and the second sheet-like resonant body 132 each include a plurality of resonant rods 50 and one or more connecting rods 60. The connecting rods 60 connect two adjacent resonant rods 50 (i.e., one or more connecting rods 60 connect two adjacent resonant rods 50 among the plurality of resonant rods 50). The first sheet-like resonant body 122 and the second sheet-like resonant body 132 may include the same or different numbers of resonant rods 50, which can be adjusted according to actual needs. Furthermore, in the first sheet-like resonant body 122 or the second sheet-like resonant body 132, the plurality of resonant rods 50 may have different or the same external shapes and structures, which can be adjusted according to actual needs.

[0045] The first sheet-shaped resonant body 122 and the second sheet-shaped resonant body 132 each include three resonant rods 50 and two connecting rods 60. The resonant rods 50 included in the first sheet-shaped resonant body 122 have different external shapes, and the resonant rods 50 included in the second sheet-shaped resonant body 132 also have different external shapes.

[0046] It should be noted that each resonant rod 50 included in the first sheet-like resonant body 122 and the second sheet-like resonant body 132 is based on its included upright section 52, and then extends outward with different extension sections according to the requirements of the resonant frequency (that is, each resonant rod 50 includes an upright section 52 fixed to the housing 110, and each resonant rod 50 can adjust the resonant frequency through different extension sections). For example, the resonant rod 50 includes an upright section 52, an extension section 54 extending from one or both sides of the upright section 52, another extension section 56 extending from the extension section 54 in a direction away from the upright section 52, and yet another extension section 58 extending from the other extension section 56 away from the extension section 54 in a parallel manner to the extension section 54. The end of the upright section 52 away from the extension section 54 is connected to the bottom plate portion 117 of the housing 110.

[0047] In this embodiment, the input resonator 120 includes the outermost resonator 50 from the plurality of resonator bars 50 (i.e., Figure 4 The leftmost resonant rod 50) includes an input terminal 124 and a first branch 126a extending outward from one side of its upright section 52, and a first branch 126b extending outward from the input terminal 124; the output resonator 130 includes the outermost resonant rod 50 (i.e., the leftmost resonant rod 50) Figure 5 The leftmost resonant rod 50 has an output end 134, second branches 136a and 136b, and a second branch 136c extending outward from the output end 134, along with the upright section 52. In one embodiment, the extension section 54, the first extension section 81 of the first branch 126a, and the second extension section 82 of the first branch 126b extend in the same direction; in another embodiment, the extension section 54, the first extension section 81 of the first branch 126a, and the second extension section 82 of the first branch 126b extend beyond the extension section 54 in the same direction. In one embodiment, the extension segment 58, the fourth extension segment 84a of the second branch 136a, the fourth extension segment 84b of the second branch 136b, and the fifth extension segment 85 of the second branch 136c extend in the same extending direction; in another embodiment, the extension segment 58, the fourth extension segment 84a of the second branch 136a, the fourth extension segment 84b of the second branch 136b, and the fifth extension segment 85 of the second branch 136c extend beyond the extension segment 58 in the extending direction.

[0048] In one embodiment, the cavity filter 100 may further include an isolation plate 140 located within the accommodating cavity 112, separating the input resonator 120 and the output resonator 130. The isolation plate 140 has at least one notch 70. Therefore, the cavity filter 100 can obtain different resonant frequencies by varying the number and position of the isolation plates 140 and their notches 70. The isolation plate 140 can be directly cut from a sheet of metal.

[0049] In one embodiment, the cavity filter 100 may further include an input device 150 and an output device 160. The input device 150 and the output device 160 are respectively engaged with the input through-hole 114 and the output through-hole 116 of the housing 110. The input end 124 passes through the input device 150 and extends out of the housing 110, and the output end 134 passes through the output device 160 and extends out of the housing 110. The input device 150 and the output device 160 may be insulating brackets and can be engaged with the input through-hole 114 and the output through-hole 116 of the housing 110 by mechanical or adhesive means.

[0050] Please see Figures 6 to 8 , Figure 6 This is an exploded view of a second embodiment of the cavity filter according to this application. Figure 7 for Figure 6 A diagram of the cavity filter combination. Figure 8 for Figure 6 A side view of the cavity filter. (See image.) Figures 6 to 8 As shown, the cavity filter 200 includes a housing 210, an input resonator 220, and an output resonator 230. The housing 210 may include a base plate 217, a side wall 218, and a cover plate 219. It should be noted that, to illustrate the internal assembly of the housing 210 of the cavity filter 200, [details omitted]. Figure 7 The cover plate 219 of the shell 210 is omitted from the drawing.

[0051] The housing 210 has a cavity 212 and is provided with an input through-hole 214 and an output through-hole 216 communicating with the cavity 212. The input resonator 220 and the output resonator 230 are located in the cavity 212 and fixed to the housing 210. Specifically, the side wall portion 218 is connected to the base plate portion 217 around it. The side wall portion 218 and the base plate portion 217 form the cavity 212 and the opening 92. One side of the cover plate portion 219 covers and is fixed to the opening 92. The input resonator 220 and the output resonator 230 are fixed to the base plate portion 217, and the input through-hole 214 and the output through-hole 216 are provided in the side wall portion 218. Therefore, the electrical connection position between the cavity filter 200 and the external circuit is located on its side.

[0052] Please see Figures 6 to 7 and Figures 9 to 10 , Figure 9 for Figure 6 A schematic diagram of the input resonator. Figure 10 for Figure 6A schematic diagram of the output resonator is shown below. In this embodiment, the input resonator 220 includes a first sheet-like resonant body 222 and an input end 224 and a first branch 226 extending outward from one side of the first sheet-like resonant body 222 (i.e., the input end 224 and the first branch 226 are spaced apart from each other). The input end 224 extends out of the housing 210 through an input through-hole 214. The output resonator 230 includes a second sheet-like resonant body 232 and an output end 234 and a second branch 236 extending outward from one side of the second sheet-like resonant body 232 (i.e., the output end 234 and the second branch 236 are spaced apart from each other). The output end 234 extends out of the housing 210 through an output through-hole 216. The lengths of both the first branch 226 and the second branch 236 are one-quarter wavelength of the resonant frequency of the cavity filter 200. The cavity filter 200 can achieve a simple filter port structure by extending the input terminal 224 of the input resonator 220 through the input through-hole 214 and the output terminal 234 of the output resonator 230 through the output through-hole 216. Furthermore, since the first segment 226 is integrally formed with the first sheet-like resonant body 222, and the second segment 236 is integrally formed with the second sheet-like resonant body 232, and the lengths of both the first segment 226 and the second segment 236 are one-quarter wavelength of the resonant frequency of the cavity filter 200, the cavity filter 200 has the function of suppressing far-end harmonics.

[0053] The input resonator 220 and the output resonator 230 have the same external structure, while the external structures of the first sheet-like resonant body 222 and the second sheet-like resonant body 232 can be designed according to the actual resonant frequency requirements.

[0054] In one embodiment, the cavity filter 200 may further include an isolation plate 240 located in the accommodating cavity 212 and separating the input resonator 220 and the output resonator 230, the isolation plate 240 having at least one notch 72.

[0055] In one embodiment, the cavity filter 200 may further include an input device 250 and an output device 260, which are respectively connected to the input through hole 214 and the output through hole 216 of the housing 210. The input end 224 passes through the input device 250 and extends out of the housing 210, and the output end 234 passes through the output device 260 and extends out of the housing 210.

[0056] Please see Figures 11 to 13 , Figure 11 This is an exploded view of a third embodiment of the cavity filter according to this application. Figure 12 for Figure 11 A diagram of the cavity filter combination. Figure 13 for Figure 11 A bottom view of the cavity filter. (See attached image.) Figures 11 to 13As shown, the cavity filter 300 includes a housing 310, an input resonator 320, an output resonator 330, and an intermediate resonator 370. The housing 310 may include a base plate 317, a side wall 318, and a cover plate 319. It should be noted that, to illustrate the internal assembly of the housing 310 of the cavity filter 300, [details omitted]. Figure 12 The cover plate 319 of the shell 310 is omitted from the drawing.

[0057] The housing 310 has a cavity 312 and is provided with an input through hole 314 and an output through hole 316 communicating with the cavity 312. The input resonator 320, the output resonator 330 and the intermediate resonator 370 are located in the cavity 312 and fixed to the housing 310. Coupled between any two of the input resonator 320, the output resonator 330 and the intermediate resonator 370. Specifically, the side wall portion 318 is connected to the base plate portion 317 around it. The side wall portion 318 and the base plate portion 317 form the cavity 312 and the opening 96. One side of the cover plate portion 319 covers and is fixed to the opening 96. The input resonator 320, the output resonator 330 and the intermediate resonator 370 are fixed to the base plate portion 317. The input through hole 314 and the output through hole 316 are provided in the base plate portion 317.

[0058] Please see Figures 11 to 17 , Figure 14 for Figure 11 A schematic diagram of the input resonator. Figure 15 for Figure 11 A schematic diagram of the output resonator. Figure 16 for Figure 11 A schematic diagram of the structure of the intermediate resonator. Figure 17 for Figure 12A cross-sectional view along line segment AA'. In this embodiment, the input resonator 320 includes a first sheet-like resonant body 322, an input end 324 extending outward from one side of the first sheet-like resonant body 322, first branches 326a and 326b, and a first branch 326c extending outward from the input end 324. The input end 324 extends out of the housing 310 through an input through-hole 314. The output resonator 330 includes a second sheet-like resonant body 332, an output end 334 extending outward from one side of the second sheet-like resonant body 332, second branches 336a and 336b, and a second branch 336c extending outward from the output end 334. The output end 334 extends out of the housing 310 through an output through-hole 316. The intermediate resonator 370 may include multiple resonant rods 10 and one or more connecting rods 20. The connecting rods 20 connect two adjacent resonant rods 10. The multiple resonant rods 10 may have different or the same external shape and structure, and can be adjusted according to actual needs. Among them, the lengths of the first branch 326a, the first branch 326b, the first branch 326c, the second branch 336a, the second branch 336b, and the second branch 336c are all one-quarter wavelength of the resonant frequency of the cavity filter 300.

[0059] Since the first segments 326a, 326b, and 326c are integrally formed with the first sheet-like resonant body 322, and the second segments 336a, 336b, and 336c are integrally formed with the second sheet-like resonant body 332, and the lengths of the first segments 326a, 326b, 326c, 336a, 336b, and 336c are all one-quarter wavelength of the resonant frequency of the cavity filter 300, the cavity filter 300 has the function of suppressing far-end harmonics.

[0060] The external structure of the input resonator 320, the output resonator 330, and the intermediate resonator 370 can be designed according to the actual resonant frequency requirements.

[0061] In one embodiment, the input resonator 320 and the output resonator 330 are spaced apart along a first direction F; the intermediate resonator 370 is spaced apart from the input resonator 320 and the output resonator 330 along a second direction S perpendicular to the first direction F, and is located between the input resonator 320 and the output resonator 330 in the first direction F. In other words, in the second direction S, the intermediate resonator 370 partially overlaps with the input resonator 320 or the output resonator 330. Therefore, coupling can be generated between the output resonator 330 and the intermediate resonator 370, and between the input resonator 320 and the intermediate resonator 370.

[0062] In one embodiment, the cavity filter 300 further includes an isolation plate 340 located in the accommodating cavity 312, which divides the accommodating cavity 312 into a first cavity 312a, a second cavity 312b, and a third cavity 312c. The input resonator 320 is located in the first cavity 312a, the output resonator 330 is located in the second cavity 312b, and the intermediate resonator 370 is located in the third cavity 312c.

[0063] In one embodiment, the cavity filter 300 may further include an input device 350 and an output device 360, which are respectively connected to the input through hole 314 and the output through hole 316 of the housing 310. The input end 324 passes through the input device 350 and extends out of the housing 310, and the output end 334 passes through the output device 360 ​​and extends out of the housing 310.

[0064] Please see Figure 18 and Figure 19 , Figure 18 for Figure 1 Simulation curves of S-parameters for a cavity filter without the first and second stubs. Figure 19 for Figure 1 The simulation curves of the S-parameters of the cavity filter. Figure 18 and Figure 19 In the graph, the horizontal axis represents frequency in gigahertz (GHz), and the vertical axis represents attenuation in decibels (dB). From Figure 18 and Figure 19 As can be seen, in the far-end frequency range (9 GHz to 18 GHz), there are no first branch 126 and second branch 136. Figure 1 The cavity filter exhibits relatively poor attenuation at frequencies of 10.028 GHz, 10.920 GHz, and 14.456 GHz, where far-end suppression is poor. Figure 1 The cavity filter 100 exhibits poor attenuation at frequencies of 9.664 GHz, 13.448 GHz, and 14.808 GHz, with the former showing a significantly larger attenuation. Therefore, it can be concluded that the cavity filter 100 with the first stub 126 and the second stub 136 has the function of suppressing far-end harmonics.

[0065] In summary, by setting the first branch of the input resonator and the second branch of the output resonator, and by ensuring that the lengths of both the first and second branches are one-quarter of the resonant frequency of the cavity filter, the cavity filter of this application has the function of suppressing far-end harmonics. Furthermore, due to its simple structure and the absence of a low-pass filter, the cavity filter reduces material costs, simplifies the manufacturing process, lowers costs, and provides good performance stability and consistency. Therefore, it can meet the requirements of miniaturization and lightweight design.

[0066] While the present invention has been described using the above embodiments, it should be noted that these descriptions are not intended to limit the invention. Rather, this invention encompasses 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 possible sense to include all obvious modifications and similar arrangements.

Claims

1. A cavity filter, characterized in that, include: A housing having a receiving cavity, the housing having an input through hole and an output through hole communicating with the receiving cavity; An input resonator, located within the accommodating cavity and fixed to the housing, includes a first sheet-like resonant body, an input terminal extending outward from one side of the first sheet-like resonant body, and a first branch, wherein the input terminal and the first branch are connected to or spaced apart from each other, and the input terminal extends out of the housing through the input through-hole; and An output resonator is located in the accommodating cavity and fixed to the housing, and includes a second sheet-like resonant body and an output end extending outward from one side of the second sheet-like resonant body, wherein the output end extends out of the housing through the output through hole; The first segment is used to generate a resonance peak.

2. The cavity filter as described in claim 1, characterized in that, The output resonator further includes a second segment extending outward from one side of the second sheet-like resonant body. The output terminal is connected to or spaced apart from the second segment, wherein the first segment and the second segment are each used to generate a resonant peak.

3. The cavity filter as described in claim 2, characterized in that, There are multiple first branches and multiple second branches.

4. The cavity filter as described in claim 2, characterized in that, The first segment includes a first extension segment extending outward from one side of the first sheet-like resonant body, or includes a second extension segment extending outward from the input end and a third extension segment extending from the end of the second extension segment away from the input end; the second segment includes a fourth extension segment extending outward from one side of the second sheet-like resonant body, or includes a fifth extension segment extending outward from the output end and a sixth extension segment extending from the end of the fifth extension segment away from the output end.

5. The cavity filter as described in claim 4, characterized in that, The first sheet-like resonant body and the second sheet-like resonant body each include a plurality of resonant rods. Each of the plurality of resonant rods includes an upright section and an extended section. The extended section extends outward from one side of the upright section. The input end and the output end extend outward from the other side of the upright section of the first sheet-like resonant body and the second sheet-like resonant body relative to the extended section, respectively. The first extension segment extends outward from one side of the upright segment of the first sheet-like resonant body and / or the second extension segment extends outward from the input end, the fourth extension segment extends outward from one side of the upright segment of the second sheet-like resonant body and / or the fifth extension segment extends outward from the output end.

6. The cavity filter as described in claim 2, characterized in that, The first sheet-shaped resonant body and the second sheet-shaped resonant body each include a plurality of resonant rods, each of the plurality of resonant rods including an upright section connected to the housing; in the input resonator, the input end extends outward from one side of the upright section of the outermost of the plurality of resonant rods and is connected to the first support section; In the output resonator, the output end and the second branch extend outward from one side of the upright section of the outermost of the plurality of resonant rods.

7. The cavity filter as described in claim 2, characterized in that, The input resonator and the output resonator are configured to receive external electrical signals through the input terminal, transmit the electrical signals through the first stub and the first sheet resonant body, transmit them through coupling to the second sheet resonant body, transmit them through the second stub, and output them from the output terminal.

8. The cavity filter as described in claim 1, characterized in that, It also includes an isolation plate located in the accommodating cavity and separating the input resonator and the output resonator, the isolation plate having at least one notch.

9. The cavity filter as described in claim 1, characterized in that, It also includes an input device and an output device, the input device and the output device respectively engaging with the input through hole and the output through hole of the housing, the input end passing through the input device and extending out of the housing, and the output end passing through the output device and extending out of the housing.

10. The cavity filter as claimed in claim 1, characterized in that, It also includes an intermediate resonator, located in the accommodating cavity and fixed to the housing; any two of the input resonator, the output resonator and the intermediate resonator are coupled together.

11. The cavity filter as described in claim 10, characterized in that, It also includes an isolation plate located in the accommodating cavity, which divides the accommodating cavity into a first cavity, a second cavity, and a third cavity. The input resonator is located in the first cavity, the output resonator is located in the second cavity, and the intermediate resonator is located in the third cavity.

12. The cavity filter as described in claim 10, characterized in that, The input resonator and the output resonator are arranged at intervals along a first direction; the intermediate resonator is spaced apart from the input resonator and the output resonator along a second direction perpendicular to the first direction, and is located between the input resonator and the output resonator in the first direction.

13. The cavity filter as described in claim 1, characterized in that, The housing further includes a bottom plate, a side wall, and a cover plate. The side wall is connected to the bottom plate, and the side wall and the bottom plate form the accommodating cavity and the opening. One side of the cover plate covers and is fixed to the opening. The input resonator and the output resonator are fixed to the bottom plate. The input through hole and the output through hole are disposed on the bottom plate or the side wall.

14. The cavity filter as claimed in claim 1, characterized in that, The first sheet-shaped resonant body and the second sheet-shaped resonant body each include a plurality of resonant rods and one or more connecting rods, wherein the one or more connecting rods connect two adjacent resonant rods among the plurality of resonant rods.

15. The cavity filter as claimed in claim 1, characterized in that, The first sheet-like resonant body and the second sheet-like resonant body each include a plurality of resonant rods. Each of the plurality of resonant rods includes an upright section and an extended section, and the extended section extends outward from one side of the upright section.

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