CN116053736A - Cavity filter - Google Patents

Abstract

The invention relates to a cavity filter, which comprises a metal cavity, a tuning screw, a dielectric base and a ceramic dielectric body, wherein the dielectric base and the ceramic dielectric body are arranged in the metal cavity; the dielectric base is arranged at the bottom of the metal cavity, the ceramic dielectric body is arranged on the dielectric base, the dielectric base supports the ceramic dielectric body, and the periphery of the ceramic dielectric body is not contacted with the inner wall of the metal cavity; the outer side surface of the ceramic dielectric body is provided with an isolation groove, the isolation groove is concavely arranged from the corresponding outer side surface to the center of the ceramic dielectric body, the isolation groove does not extend into the center of the ceramic dielectric body, the ceramic dielectric body is divided into a plurality of dielectric units through the isolation groove, and the dielectric units are arranged around the center of the ceramic dielectric body; the ceramic dielectric body is also provided with a frequency hole, and the tuning screw rod extends into the frequency hole and is not contacted with the inner wall of the frequency hole. The invention has compact structure, high performance and miniaturization of the filter.

Description

Cavity filter

[ field of technology ]

The invention relates to the technical field of wireless communication radio frequency, in particular to a cavity filter.

[ background Art ]

With the rapid development of wireless communication industry and the increasing shortage of radio spectrum resources, particularly the urgent need for high quality 5G communication, wireless communication devices come with new opportunities and challenges. As an important component of the rf front-end, filters are used to transmit the desired signal with low loss in the passband and suppress the undesired signal in the limited stopband, with performance directly affecting the overall performance of the communication system. In addition, the requirements for energy saving and emission reduction of the wireless communication system and the trend requirements for miniaturization, high performance and the like of the system are met, and miniaturization and high performance of the filter are required to keep pace with the trend.

The traditional cavity filter is not easy to destroy, but has large volume and large loss, and cannot meet the requirements of miniaturization and high performance of the existing wireless communication system and high-quality 5G. A high-k dielectric filter can achieve lower loss and smaller volume; but pure dielectric filters are vulnerable, for example: ceramic dielectric filters are fragile. Therefore, research on how to combine the advantages of both, achieving miniaturization and high performance of the filter is necessary.

[ invention ]

The invention aims to provide a cavity filter which has a compact structure, keeps high performance and is miniaturized.

The cavity filter comprises a metal cavity, a tuning screw rod, a dielectric base and a ceramic dielectric body, wherein the dielectric base and the ceramic dielectric body are arranged in the metal cavity; the dielectric base is arranged at the bottom of the metal cavity, the ceramic dielectric body is arranged on the dielectric base and supported by the dielectric base, and the periphery of the ceramic dielectric body is not contacted with the inner wall of the metal cavity; the outer side surface of the ceramic dielectric body is provided with an isolation groove, the isolation groove is concavely arranged from the corresponding outer side surface to the center of the ceramic dielectric body, and the isolation groove does not extend into the center of the ceramic dielectric body; the ceramic dielectric body is divided into a plurality of media by a separation groove

The dielectric units are arranged around the center of the ceramic dielectric body; the ceramic dielectric body 5 is also provided with a frequency hole, and the tuning screw rod extends into the frequency hole and is not contacted with the inner wall of the frequency hole.

As an optimal technical scheme, the isolation groove is a through groove or a blind groove penetrating through the ceramic dielectric body in the height direction, and the cross section of the isolation groove is rectangular, T-shaped or cross-shaped.

As a preferable technical scheme, the ceramic dielectric body is square and is provided with four isolation grooves and four dielectric units, so that two mutually perpendicular degenerate modes of resonance frequencies are formed.

0 as a preferable technical scheme, the frequency hole is a round hole, and the frequency hole is arranged on the medium sheet

And the frequency holes are arranged in the direction from the top of the ceramic dielectric body to the bottom of the metal cavity, and are through holes or blind holes.

As an optimal technical scheme, the number of the frequency holes is two, and the frequency holes are respectively arranged at two sides of any isolation groove

Or the centers of the two dielectric units 5 respectively arranged at any side of the ceramic dielectric body.

As a preferable technical scheme, the outer surface of the ceramic dielectric body is not coated with a metal layer, or only one of the upper surface or the lower surface of the ceramic dielectric body is coated with the metal layer.

Preferably, the depth of the recess of the isolation groove from the outer side to the center of the ceramic dielectric body exceeds 3 mm.

0 as a preferable technical scheme, the medium base is a one-piece integral formed by alumina or teflon materials.

As a preferable technical scheme, the medium base is fixed in the central area of one inner wall surface of the metal cavity through a fastener or a connecting piece.

As an optimal technical scheme, the cavity filter is formed by mutually connecting the side surfaces of a plurality of metal cavities.

The invention accommodates the ceramic dielectric body in a metal cavity, and the ceramic dielectric body is provided with the isolation groove and the frequency hole, so that the overall structure is compact, and the miniaturization of the filter is realized while the high performance is maintained.

[ description of the drawings ]

Fig. 1 is a schematic perspective view of a cavity filter according to a first embodiment of the present invention;

FIG. 2 is a schematic top view of the cavity filter of FIG. 1;

FIG. 3 is a schematic perspective view of a dielectric base and ceramic dielectric body of the cavity filter of FIG. 1;

FIG. 4 is a perspective view of a dielectric base of the cavity filter of FIG. 1;

FIG. 5 is a schematic cross-sectional view of the media base of FIG. 4;

fig. 6 is a schematic top view of a cavity filter according to a second embodiment of the present invention;

fig. 7 is a schematic top view of a cavity filter according to a third embodiment of the present invention;

fig. 8 to 10 are schematic top views of a metal cavity and a ceramic dielectric body according to other embodiments of the present invention, respectively.

[ detailed description ] of the invention

The invention is further described below with reference to the drawings and examples.

Embodiment one:

referring to fig. 1 to 3, the present invention provides a cavity filter 100 including a metal cavity 1, a tuning screw 3, a dielectric base 5 accommodated in the metal cavity 1, and a ceramic dielectric body 8.

Wherein:

the medium base 5 is arranged at the bottom of the metal cavity 1; the ceramic dielectric body 8 is disposed on the dielectric base station 5, and the ceramic dielectric body 8 is supported by the dielectric base station 5. The outer periphery of the ceramic dielectric body 8 does not contact the inner wall of the metal cavity 1. As shown in fig. 3, in this embodiment, the outer surface of the ceramic dielectric body 8 is not coated with a metal layer; the ceramic dielectric body 8 exposes the ceramic material. It will be appreciated that the structure of the cavity filter 100 does not require the ceramic dielectric body 8 to have a grounding property, yet maintains its stable and good performance.

The inner wall of the metal cavity 1 is coated with a metal layer. Preferably, the metal layer is an integrated metal layer structure formed by coating one of silver, gold or copper. The outer side surface of the ceramic dielectric body 8 is provided with a separation groove 81, the separation groove 81 is concavely arranged from the corresponding outer side surface to the center of the ceramic dielectric body 8, namely, the separation groove 81 is arranged towards the center of the ceramic dielectric body 8, and the separation groove 81 does not extend into the center of the ceramic dielectric body 8. The ceramic dielectric body 8 is partitioned into a plurality of dielectric units 80 by a partition groove 81, and the plurality of dielectric units 80 are arranged around the center of the ceramic dielectric body 8. Specifically, the isolation groove 81 is recessed more than 3 mm from the outer side toward the center of the ceramic dielectric body 8, but does not interrupt the connection of the plurality of dielectric units 80; the plurality of media units 80 are still a one-piece unitary body.

Preferably, the ceramic dielectric body 8 is square with four isolation trenches 81 and four dielectric elements 80, thereby forming two mutually perpendicular degenerate modes of resonance frequencies. Specifically, four isolation grooves 81 are symmetrically provided on four sides of the square ceramic dielectric body 8, respectively. The isolation groove 81 is a through groove or a blind groove penetrating the ceramic dielectric body 8 in the height direction.

The ceramic dielectric body 8 is also provided with a frequency hole 83, and the tuning screw 3 extends into the frequency hole 83 and is not in contact with the inner wall of the frequency hole 83. Specifically, the frequency holes 83 are provided from the top surface of the ceramic dielectric body 8 toward the bottom of the metal cavity 1, which are through holes or blind holes. Preferably, the frequency holes 83 are circular holes.

As shown in fig. 1 to 3, in the present embodiment, there are two frequency holes 83, and the two frequency holes 83 are respectively provided in the center of the dielectric unit 80 on both sides of any one of the isolation grooves 81. And two frequency holes 83 extend into a tuning screw 3, respectively, for frequency tuning.

Referring to fig. 4 and 5, in the present embodiment, the dielectric base 5 is a one-piece unitary body molded of alumina or teflon material. The dielectric base 5 is fixed to the inner wall surface of the bottom of the metal cavity 1 by a fastener such as a screw. For example, the dielectric base 5 is provided with an axial mounting hole 52 for a screw to pass through, and preferably, the mounting hole 52 has a larger inner diameter at an upper section and a smaller inner diameter at a lower section, so that a step 54 is formed, and the nut of the screw can be accommodated in the upper section and limited by the step 54. In an alternative scheme, the medium base 5 can be fixed on the inner wall surface of the bottom of the metal cavity 1 through a connecting piece such as adhesive or soldering tin.

It should be noted that the cavity filter 100 can also be combined into a cascade structure, and any one of four sides of the plurality of metal cavities 1 of the cavity filter 100 is connected to each other, thereby forming a cascade structure.

Embodiment two:

referring to fig. 6, the main difference between this embodiment and the first embodiment is that two frequency holes 83 are respectively provided at the corners of two dielectric elements 80 on either side of the ceramic dielectric body. And frequency holes 83 at corners of the two dielectric units 80 are also respectively extended with a tuning screw 3.

Embodiment III:

referring to fig. 7, this embodiment is different from the first and second embodiments in that a through hole 85 is further provided in the center of the ceramic dielectric body 8, and the through hole 85 facilitates fastening of the dielectric base 5 to the inner wall surface of the bottom of the metal cavity 1 by a fastener such as a screw. Simultaneously, one of the upper surface or the lower surface of the ceramic dielectric body 8 is coated with a metal layer; the other surfaces of the ceramic dielectric body 8 are not yet coated with a metal layer.

Embodiment four:

referring to fig. 8, this embodiment differs from the third embodiment in that the surface of the ceramic dielectric body 8 is not coated with a metal layer.

Referring to fig. 9 and 10, in other embodiments, the shape of the isolation groove 81 may be variously designed. The isolation groove 81 may be designed in a rectangular shape, a T-shape, or a cross shape. As shown in fig. 8, the cross section of the isolation groove is rectangular; FIG. 9 shows a cross section of the isolation trench having a T-shape; as shown in fig. 10, the isolation groove has a cross-shaped cross section.

When the rectangular, T-shaped or cross-shaped isolation groove 81 is used in cooperation with the through hole 85 in the center of the ceramic dielectric body 8, the through hole 85 is preferably a circular hole.

The cavity filter 100 of all the above embodiments has a compact structure, achieves miniaturization of the volume, and has high performance. The size of the circular hole of the frequency hole 83 and the length of the tuning screw 3 extending into the frequency hole 83 can be adjusted to adjust the resonant frequency and the coupling amount of the filter and two mutually perpendicular degenerate modes.

The foregoing examples only illustrate preferred embodiments of the invention, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that modifications and improvements can be made without departing from the spirit of the invention, such as combining different features of the various embodiments, which are all within the scope of the invention.

Claims (10)

1. The cavity filter comprises a metal cavity and a tuning screw rod, and is characterized by further comprising a dielectric base and a ceramic dielectric body which are arranged in the metal cavity; the dielectric base is arranged at the bottom of the metal cavity, the ceramic dielectric body is arranged on the dielectric base and supported by the dielectric base, and the periphery of the ceramic dielectric body is not contacted with the inner wall of the metal cavity; the outer side surface of the ceramic dielectric body is provided with an isolation groove, the isolation groove is concavely arranged from the corresponding outer side surface to the center of the ceramic dielectric body, and the isolation groove does not extend into the center of the ceramic dielectric body; the ceramic dielectric body is divided into a plurality of dielectric units through isolating grooves, and the dielectric units are arranged around the center of the ceramic dielectric body; the ceramic dielectric body is also provided with a frequency hole, and the tuning screw rod extends into the frequency hole and is not contacted with the inner wall of the frequency hole.

2. The cavity filter of claim 1, wherein the isolation trench is a through trench or a blind trench extending through the ceramic dielectric in a height direction, and the cross section of the isolation trench is rectangular, T-shaped or cross-shaped.

3. The cavity filter of claim 1, wherein said ceramic dielectric body is square with four said isolation trenches and four said dielectric elements, thereby forming two mutually perpendicular degenerate modes of resonance frequencies.

4. The cavity filter according to claim 1, wherein the frequency holes are round holes, the frequency holes are arranged in the dielectric unit, the frequency holes are arranged in a direction from the top of the ceramic dielectric body to the bottom of the metal cavity, and the frequency holes are through holes or blind holes.

5. The cavity filter of claim 1, wherein the number of the frequency holes is two, and the frequency holes are respectively arranged at the centers of the dielectric units at two sides of any isolation groove or at the corners of the two dielectric units at any side of the ceramic dielectric body.

6. The cavity filter of claim 1, wherein no metal layer is applied to an outer surface of the ceramic dielectric body or only one of an upper surface or a lower surface of the ceramic dielectric body.

7. The cavity filter of claim 1, wherein the isolation trenches are recessed to a depth of more than 3 millimeters from the outer side toward the center of the ceramic dielectric body.

8. The cavity filter of claim 1, wherein the dielectric base is a one-piece monolith formed of alumina or teflon material.

9. The cavity filter according to claim 8, wherein said dielectric base is fixed to a central region of an inner wall surface of the metal cavity by a fastener or a connector.

10. The cavity filter of claim 1, wherein the cavity filter is a cascade structure formed by interconnecting sides of a plurality of metal cavities.

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