A low frequency filter

Abstract

The present invention discloses a low-frequency filter, including a plurality of resonators arranged in a cavity, wherein the resonator includes a disk-shaped portion; in two adjacent resonators, the disk-shaped portion of one resonator extends outward to directly below or directly above the disk-shaped portion of the other resonator, so that the two adjacent resonators form a capacitive coupling, replacing the inductive coupling between two adjacent resonators in a conventional filter. In addition to the capacitive coupling between the resonator and the cover plate, the present invention also adds the capacitive coupling between adjacent resonators. Under the same single cavity size conditions, the structure of the present invention can significantly reduce the frequency of the single cavity and improve the Q value of the single cavity. The coupling between adjacent resonators is also mainly capacitive coupling, and the resonator is provided with a coupling tuning avoidance hole for easy debugging. The present invention has a simple structural design, convenient processing, simple debugging, and light weight, and is suitable for 5G miniaturized products, fully meeting the requirements of 5G communication base station construction for miniaturization of functional modules.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency communication, and in particular to a low-frequency filter. Background Art

[0002] As a key component of the RF front-end of a mobile base station, the performance of the transceiver filter directly affects the quality of communication. With the development of mobile communication networks and the application of massive MIMO antennas in 5G communication systems, the number of front-end filters will increase significantly, which puts higher requirements on the miniaturization, lightweight and integration of the filters.

[0003] In the prior art, the coaxial cavity filter relies on the capacitive coupling between the resonator disk and the cover plate to reduce the frequency. Generally, when the frequency requirement is low, it is mainly achieved by increasing the diameter of the resonator disk, reducing the distance between the resonator disk and the cover plate, turning down the resonator disk, and dielectric loading. When the structural size is small and the space is limited, it is difficult to achieve the requirements of low frequency and high Q value. In addition, windows are opened between adjacent cavities to achieve inductive coupling. When the inductive coupling is not strong enough due to space and size constraints, reinforcement or metal sheets are added between the two resonators to enhance the coupling. This makes it more difficult to achieve low frequency requirements, and the Q value of a single cavity will also be reduced. Summary of the invention

[0004] The object of the present invention is to provide a low-frequency filter, comprising a cavity, in which a plurality of resonators are arranged; the resonator comprises: a columnar portion, and a disk-shaped portion located at the top of the columnar portion; the characteristic is that: among two adjacent resonators, the disk-shaped portion of one resonator extends outward to just below or just above the disk-shaped portion of the other resonator, so that the two adjacent resonators form capacitive coupling, replacing the inductive coupling between the two adjacent resonators in a conventional filter.

[0005] Preferably, the disc-shaped portion extends outwardly to form a folded edge, and the disc-shaped portion has one, two or more folded edges, and at least one folded edge extends to directly below or directly above an adjacent disc-shaped portion.

[0006] Preferably, the folded edge is folded upward or downward; the folded edge is folded twice or more.

[0007] Preferably, a first tuning rod is provided between two adjacent resonators.

[0008] Preferably, the folded edge directly opposite to the first tuning rod is provided with an avoidance hole for the first tuning rod to pass through.

[0009] Preferably, the disc-shaped portion is circular or polygonal.

[0010] Preferably, the polygon is a square.

[0011] Preferably, the top of the cavity is closed by a cover plate, and the resonator is capacitively coupled to the cover plate; and the first tuning rod is arranged on the cover plate.

[0012] Preferably, the cover plate is also provided with a second tuning rod directly facing the resonator.

[0013] Preferably, the cover plate is provided with screw holes for installing the first tuning rod and the second tuning rod, and the first tuning rod and the second tuning rod are respectively threadedly connected to the corresponding screw holes.

[0014] Preferably, the cover plate is fixedly connected to the cavity by fastening screws; and radio frequency connectors are respectively provided at both ends of the cavity.

[0015] The low-frequency filter of the present invention has the following advantages and beneficial effects:

[0016] In addition to the capacitive coupling between the resonator and the cover plate, the structure of the present invention also increases the capacitive coupling between adjacent resonators. Under the same single cavity size conditions, the structure of the present invention can significantly reduce the single cavity frequency and improve the single cavity Q value. The coupling between adjacent resonators is also mainly capacitive coupling. The resonator is provided with a coupling tuning avoidance hole for easy debugging.

[0017] The structural method of the present invention makes it easier to realize a low-frequency filter product with a small structural size and a high Q value. The structural design of the present invention is simple, the processing is convenient, the debugging is simple, and the weight is light. It is suitable for 5G miniaturized products and fully meets the requirements of 5G communication base station construction for the miniaturization of functional modules.

[0018] The filter of the present invention has simple processing and installation methods, which brings convenience to the assembly, debugging and maintenance of the filter, thereby improving efficiency and reducing costs.

[0019] Capacitive coupling is performed between two adjacent resonators through a coupling window. In order to ensure that the coupling window is capacitive, the present invention extends the disk-shaped portion of one resonator outward to just below or just above the disk-shaped portion of another resonator, thereby realizing a capacitive coupling coupling window. The smaller the distance of the coupling window, the stronger the capacitive coupling strength.

[0020] In addition, the coupling strength between two adjacent resonators can also be tuned by adjusting the first tuning rod located between the two adjacent resonators. The first tuning rod is arranged directly above the coupling windows of the two adjacent resonators. The deeper the first tuning rod extends into the cavity, the weaker the capacitive coupling strength between the two adjacent resonators. This can improve space utilization, make equipment simpler, increase structural and performance stability, and also greatly improve intermodulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is an appearance diagram of the filter of the present invention;

[0022] Figure 2 is an exploded diagram of the filter of the present invention;

[0023] Figures 3 to 9 is a schematic diagram of the disk-shaped portion and the folded edge of the resonator;

[0024] Fig.10 is a schematic diagram of the coupling window between two adjacent resonators. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0026] The technical solutions specifically implemented in the present invention are as follows:

[0027] like Figures 1 to 10 As shown, a low-frequency filter comprises a cavity 1, in which a plurality of resonators 2 are arranged; the resonator 2 comprises: a columnar portion 21, and a disc-shaped portion 22 located at the top of the columnar portion 21; the top of the cavity 1 is closed by a cover plate 3, and the resonator 2 is capacitively coupled with the cover plate 3;

[0028] Two adjacent resonators 2, wherein the disk-shaped portion 22 of one resonator 2 extends outward to directly below or directly above the disk-shaped portion 22 of the other resonator 2, so that the two adjacent resonators 2 form a capacitive coupling, replacing the inductive coupling between the two adjacent resonators in a conventional filter;

[0029] More specific:

[0030] The disc-shaped portion 22 is as follows Figure 3 The square shape shown in FIG. 1 is a square shape, but it should be noted that the disc-shaped portion 22 may also be Figure 4 The circular shape shown;

[0031] The disc-shaped portion 22 extends outward to form a folded edge 23;

[0032] The folded edge 23 is folded downward (such as Figure 3 As shown), it should be noted that the folded edge 23 can also be Figure 5 Fold upward as shown;

[0033] The folded edge 23 is folded twice (such as Figure 3 As shown), it should be noted that the folded edge 23 can also be Figure 6 The one shown has been folded many times;

[0034] The disc-shaped portion 22 is provided with a folded edge 23 (such as Figure 3 As shown, it should be noted that the disc-shaped portion 22 may also be provided with two folded edges 23 (as shown in FIG. Figure 7As shown) or multiple folded edges 23 (as shown Figure 8 The three fold edges 23 shown, such as Fig. 9 The four folded edges 23 shown in the figure), and at least one folded edge 23 extends to the bottom or top of the adjacent disc-shaped portion 22;

[0035] A first tuning rod 41 is provided between two adjacent resonators 2, and the first tuning rod 41 is provided on the cover plate 3; a folded edge 23 directly opposite to the first tuning rod 41 is provided with an avoidance hole 24 for the first tuning rod 41 to pass through;

[0036] The cover plate 3 is also provided with a second tuning rod 42 facing the resonator 2;

[0037] The cover plate 3 is provided with screw holes 31 for installing the first tuning rod 41 and the second tuning rod 42. The first tuning rod 41 and the second tuning rod 42 are respectively threadedly connected to the corresponding screw holes 31;

[0038] The cover plate 3 is fixedly connected to the cavity 1 by means of fastening screws 5 ; radio frequency connectors 6 are also provided at both ends of the cavity 1 .

[0039] Two adjacent resonators 2 are capacitively coupled via a coupling window 7. To ensure that the coupling window 7 is capacitive, the present invention extends the disk-shaped portion 22 of one resonator 2 outward to just below or just above the disk-shaped portion 22 of the other resonator 2, thereby realizing a capacitively coupled coupling window 7. The smaller the distance of the coupling window 7, the stronger the capacitive coupling strength.

[0040] In addition, the coupling strength between two adjacent resonators 2 can also be tuned by adjusting the first tuning rod 41 located between the two adjacent resonators 2. The first tuning rod 41 is arranged directly above the coupling window 7 of the two adjacent resonators 2. The deeper the first tuning rod 41 extends into the cavity 1, the weaker the capacitive coupling strength between the two adjacent resonators 2. This can improve space utilization, make equipment simpler, increase structural and performance stability, and also greatly improve intermodulation.

[0041] In addition to the capacitive coupling between the resonator 2 and the cover plate 3, the structure of the present invention also increases the capacitive coupling between adjacent resonators 2. Under the same single cavity size conditions, the structure of the present invention can significantly reduce the single cavity frequency and improve the single cavity Q value. The coupling between adjacent resonators 2 and resonators 2 is also mainly capacitive coupling. The resonator 2 is provided with a coupling tuning avoidance hole 24 for easy debugging.

[0042] The structural method of the present invention makes it easier to realize a low-frequency filter product with a small structural size and a high Q value. The structural design of the present invention is simple, the processing is convenient, the debugging is simple, and the weight is light. It is suitable for 5G miniaturized products and fully meets the requirements of 5G communication base station construction for the miniaturization of functional modules.

[0043] The filter of the present invention has simple processing and installation methods, which brings convenience to the assembly, debugging and maintenance of the filter, thereby improving efficiency and reducing costs.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-frequency filter, comprising a cavity, in which a plurality of resonators are arranged; the resonators include a disc-shaped portion; characterized in that: Two adjacent resonators, wherein the disk-shaped portion of one resonator extends outward to directly below or directly above the disk-shaped portion of the other resonator, so that the two adjacent resonators form capacitive coupling; The disc-shaped portion extends outwardly to form a folded edge, and the disc-shaped portion has one, two or more folded edges; The folded edge is folded upward or downward; and the folded edge is folded twice or more; A first tuning rod is provided between two adjacent resonators; The folded edge directly facing the first tuning rod is provided with an avoidance hole for the first tuning rod to pass through; The disc-shaped portion is circular or polygonal; the polygon is square; The top of the cavity is closed by a cover plate, and the resonator is capacitively coupled to the cover plate; the first tuning rod is arranged on the cover plate; The cover plate is also provided with a second tuning rod directly facing the resonator; The cover plate is provided with screw holes for installing the first tuning rod and the second tuning rod, and the first tuning rod and the second tuning rod are respectively threadedly connected with the corresponding screw holes.

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