WO2017113170A1

WO2017113170A1 - Cavity filter

Info

Publication number: WO2017113170A1
Application number: PCT/CN2015/099825
Authority: WO
Inventors: 茹志云; 陈启泰
Original assignee: 深圳市大富科技股份有限公司
Priority date: 2015-12-30
Filing date: 2015-12-30
Publication date: 2017-07-06
Also published as: CN107615573A

Abstract

Disclosed is a cavity filter, comprising: a cavity, provided with an opening on one surface thereof; a cover plate, used for sealing the cavity, wherein the cover plate comprises a cover plate body and a threaded sleeve fixed to the cover plate body, and a threaded hole is provided in the threaded sleeve; a tuning threaded rod, threadedly connected to the threaded hole. The threaded hole comprises a smooth wall thread-free area close to the cavity and an internal thread area away from the cavity; the hardness of the material of the threaded sleeve is greater than that of the cover plate body. The present invention can reduce the passive intermodulation interference produced between a tuning threaded rod and a cover plate.

Description

Cavity filter

【技术领域】[Technical Field]

The present invention relates to the field of filters, and more particularly to a cavity filter.

【背景技术】【Background technique】

Passive intermodulation products are produced when two or more signals are mixed in a non-linear passive device such as a duplexer, connector. In a multi-frequency environment, the number of intermodulation products varies with the number of transmission channels and passive intermodulation (English name: Passive) Inter Modulation, English abbreviation: PIM) increases dramatically as the product order increases. The generation of PIM (Passive Intermodulation) interference in communication systems basically comes from two passive nonlinearities: contact nonlinearity and material nonlinearity. The contact nonlinearity is the main reason for the intermodulation, and it is more difficult to solve.

In passive cavity filters, PIM caused by contact nonlinearity mainly includes: 1) looseness and sliding of metal contacts and the presence of oxide layers and contaminants; 2) point contact caused by non-360 degree joints on the joint surface Mechanical effects; 3) caused by contact with different material devices.

In current cavity filters, the tuning screw and the cover are threaded, and the threads on the cover are directly tapped through the tap. Since the thread is helical, the solid adjustment screw is actually a gradual, non-linear contact at the end of the cover thread. The combination of the tuning screw and the cover plate is the largest current density in the entire resonant cavity, and finally the combination of the tuning screw and the resonant surface of the cover plate generates a strong intermodulation source, which generates strong passive intermodulation interference.

Therefore, it is desirable to provide a cavity filter to solve the above technical problems.

【发明内容】 [Summary of the Invention]

The technical problem to be solved by the present invention is to provide a cavity filter capable of reducing passive intermodulation interference of a cavity filter.

In order to solve the above technical problem, a technical solution adopted by the present invention is to provide a cavity filter, the cavity filter includes: a cavity, the cavity is open on one side, and a cover plate for covering the cavity and the cover The utility model comprises a cover body and a threaded sleeve fixed to the cover body, wherein the threaded sleeve is provided with a threaded hole; the tuning screw is screwed with the threaded hole, the threaded hole comprises a smooth wall toothless area close to the cavity and an internal thread away from the cavity The material hardness of the threaded sleeve is greater than the material hardness of the cover body.

Wherein, the pitch of the thread on the internal thread area is less than or equal to 0.35 mm.

Wherein, the pitch of the thread on the internal thread area is equal to 0.35 mm.

Wherein, the cover plate comprises a cover body and a threaded sleeve fixed to the cover body, the threaded hole is formed on the threaded sleeve, and the material hardness of the threaded sleeve is greater than the material hardness of the cover body.

The material of the threaded sleeve is copper, and the material of the cover body is aluminum.

Wherein, the entire surface of the tuning screw is externally threaded.

Wherein, one end of the threaded sleeve close to the cavity is flush with the surface of the cover plate close to the cavity, and one end of the threaded sleeve away from the cavity is flush with the surface of the cover plate away from the cavity.

Wherein, the tuning screw comprises a first section and a second section arranged along the length direction thereof and sequentially along the direction of the cavity, the outer surface of the first section is provided with an external thread, the surface of the second section is smooth, and the outer diameter of the second section Less than the outer diameter of the first section, the end of the edentulous region adjacent to the cavity is provided with a ring of protrusions.

Wherein, one end of the threaded sleeve close to the cavity is flush with the surface of the cover plate close to the cavity, and one end of the threaded sleeve away from the cavity extends beyond the surface of the cover plate away from the cavity.

Wherein, the cavity filter further comprises a nut fixedly sleeved on the tuning screw.

Wherein, the cavity filter further comprises a gasket sleeved on the tuning screw and located between the nut and the cover.

Wherein the cavity comprises a bottom surface and a sidewall perpendicular to the bottom surface, the resonant rod is fixed to the bottom surface and the resonant rod has an upper opening facing the tuning screw and having an inner diameter larger than the outer diameter of the tuning screw.

Wherein, the bottom surface has a boss, the resonant rod has a lower opening toward the bottom surface, the lower opening is sleeved on the boss, and the tuning rod is fixed to the boss by screws.

Wherein, the upper opening is cylindrical and concentric with the tuning screw.

Wherein, between the dentless zone and the internal thread zone: 0 < D1 - D2 < 0.5 mm, wherein D1 is the inner diameter of the edentulous zone, and D2 is the inner diameter of the internal thread zone.

The beneficial effects of the present invention are: different from the prior art, the present invention provides that the threaded hole on the cover plate is arranged to include a smooth wall toothless region corresponding to the strong electric field region and an internal thread region corresponding to the weak electric field region, It can eliminate the passive intermodulation interference caused by the gradual nonlinear metal contact in the current-sensitive strong electric field region when the tuning screw and the screw hole contact rotation adjustment, thereby improving the intermodulation straight-through rate of the cavity filter product.

【附图说明】 [Description of the Drawings]

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

2 is a schematic structural view of a cavity filter according to a second embodiment of the present invention.

【具体实施方式】【detailed description】

The invention will now be described in detail in conjunction with the drawings and embodiments.

Please refer to FIG. 1. FIG. 1 is a schematic structural diagram of a cavity filter according to a first embodiment of the present invention. In the present embodiment, the cavity filter includes a cavity 10 that is open on one side, a cover plate 11 that covers the cavity 10, and a tuning screw 14 that is screwed to a threaded hole 13 provided in the cover plate 11.

The cover plate 11 includes a cover body 111 and a threaded sleeve 112 fixed to the cover body 111. The threaded hole 13 is formed on the threaded sleeve 112, and the material hardness of the threaded sleeve 112 is greater than the material hardness of the cover body 111. The fine teeth that are tapped on the threaded sleeve 112 of the hard material are relatively stable and have high strength, so that the strength of the threaded hole 13 is high, and the upper thread is not easily damaged. More preferably, the material of the threaded sleeve 112 is copper, and the material of the cover body 111 is aluminum. Of course, in other embodiments, the cover body 111 and the threaded sleeve 112 may also be of other materials.

Preferably, the cavity filter further includes a resonant rod 12 that is fixed inside the cavity 10. In other embodiments, the cavity filter may also not include the resonant rod 12.

The threaded bore 13 includes a smooth, toothless region 131 proximate the cavity 10 and an internally threaded region 132 remote from the cavity. Preferably, when the cavity filter is in operation, the cover plate 11 is formed along its thickness and adjacent the cavity The weak electric field region and the strong electric field region, which are sequentially distributed in the 10 direction, the threaded hole 13 includes a smooth wall toothless region 131 corresponding to the strong electric field region and an internal thread portion 132 corresponding to the weak electric field region. The strong electric field region and the weak electric field region are formed by the skin effect, and the strong electric field is distributed on the side surface of the cap plate 11 close to the cavity 11 and the resonance rod 12. The inner wall of the edentulous region of the threaded hole 13 is smooth, and no thread is provided.

Preferably, the pitch of the threads on the internally threaded portion 132 is less than or equal to 0.35 mm, that is, the teeth of the tuning screw 14 and the cover plate 11 are short pitched fine teeth. More preferably, the pitch of the threads on the internally threaded region 132 is equal to 0.35 mm. For example, the M5 screw uses a pitch of 0.35 to make the two fit tighter, thus reducing the nonlinear effect caused by the spiral gradation. Of course, in other embodiments, the pitch of the threads on the internally threaded region 132 may also be the value of the pitch of the other fine teeth.

Preferably, the entire surface of the tuning screw 14 is externally threaded. Preferably, one end of the threaded sleeve 112 near the cavity 10 is flush with the surface of the cover plate 11 near the cavity 10, and one end of the threaded sleeve 112 away from the cavity 10 is flush with the surface of the cover plate 11 away from the cavity 10, ie, As shown in FIG. 1, the upper surface of the threaded sleeve 112 is flush with the upper surface of the cover plate 11, and the lower surface of the threaded sleeve 112 is flush with the lower surface of the cover plate 11. Of course, in other embodiments, the end of the threaded sleeve 112 near the cavity 10 and the surface of the cover 11 adjacent to the cavity 10 may not be flush, and the end of the threaded sleeve 112 away from the cavity 10 and the cover 11 away from the cavity 10 The surface can also be uneven,

Preferably, the cavity filter further includes a nut 15 that is fixedly sleeved on the tuning screw 14.

Preferably, the cavity filter further includes a gasket 16 that is sleeved on the tuning screw 14 and located between the nut 15 and the cover plate 11. More preferably, the washer 16 is located between the nut 15 and the threaded sleeve 112.

Preferably, the cavity 10 includes a bottom surface 101 and a side wall 102 perpendicular to the bottom surface 101, the resonant rod 12 is fixed to the bottom surface 101 and the resonant rod 12 has an upper opening 141 that faces the tuning screw 14 and has an inner diameter greater than the outer diameter of the tuning screw 14.

Preferably, the bottom surface 101 has a boss 1011, the resonant rod 12 has a lower opening toward the bottom surface, the lower opening is sleeved on the boss 1011, and the tuning rod 12 is fixed to the boss 1011 by screws 17.

Preferably, the upper opening 141 is cylindrical and concentric with the tuning screw 14.

Preferably, between the toothless zone 131 and the internally threaded zone 132: 0 < D1 - D2 < 0.5 mm, wherein D1 is the inner diameter of the edentulous zone 131 and D2 is the inner diameter of the internally threaded zone 132. Preferably, D1-D2 = 0.35 mm.

Preferably, the length H of the edentulous zone is 0.5 mm, although other length values may be used in other embodiments.

Please refer to FIG. 2. FIG. 2 is a schematic structural diagram of a cavity filter according to a second embodiment of the present invention. In the present embodiment, the difference from the first embodiment of the present invention is that the tuning screw 24 includes a first segment 241 and a second segment 242 disposed along its length direction and sequentially along the direction toward the cavity 20, first The outer surface of the segment 241 is provided with an external thread, the second segment 242 has a smooth surface, the outer diameter of the second segment 242 is smaller than the outer diameter of the first segment 241, and the end of the toothless region 131 adjacent to the cavity 20 is provided with a ring of protrusions 21. One end of the threaded sleeve 212 near the cavity 20 is flush with the surface of the cover plate 21 near the cavity 20, and one end of the threaded sleeve 212 away from the cavity 20 extends beyond the surface of the cover plate 21 away from the cavity 20, that is, the upper surface of the threaded sleeve 212 is beyond On the upper surface of the cover plate 21, the lower surface of the threaded sleeve 212 is flush with the lower surface of the cover plate 21.

The invention can eliminate the current in the adjustment of the tuning screw and the screw hole contact rotation by setting the threaded hole on the cover plate to include the smooth wall toothless region corresponding to the strong electric field region and the internal thread region corresponding to the weak electric field region. The sensitive strong electric field region has passive intermodulation interference caused by the gradual nonlinear metal contact, thereby improving the intermodulation straight-through rate of the cavity filter product.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims

A cavity filter, characterized in that the cavity filter comprises:

a cavity, the cavity being open on one side;

a cover plate for covering the cavity, the cover plate comprising a cover body and a threaded sleeve fixed to the cover body, wherein the threaded sleeve is provided with a threaded hole;

a tuning screw threadedly coupled to the threaded bore, the threaded bore including a smooth wall toothless region adjacent the cavity and an internal threaded region remote from the cavity, the threaded sleeve having a material hardness greater than the cover The material hardness of the main body.
The cavity filter according to claim 1, wherein a pitch of the thread on the internally threaded portion is less than or equal to 0.35 mm.
The cavity filter of claim 2 wherein the pitch of the threads on the internally threaded region is equal to 0.35 mm.
The cavity filter according to claim 1, wherein the threaded sleeve is made of copper, and the cover body is made of aluminum.
A cavity filter according to any one of claims 1 to 4, wherein the entire surface of the tuning screw is externally threaded.
The cavity filter according to claim 5, wherein an end of the threaded sleeve adjacent to the cavity is flush with a surface of the cover plate adjacent to the cavity, and the threaded sleeve is away from the cavity One end of the body is flush with the surface of the cover plate away from the cavity.
The cavity filter according to any one of claims 1 to 3, wherein the tuning screw includes a first segment and a second segment disposed along a length direction thereof and sequentially in a direction close to the cavity, the first The outer surface of the segment is provided with an external thread, the surface of the second segment is smooth, the outer diameter of the second segment is smaller than the outer diameter of the first segment, and the toothless region is provided with a ring near the end of the cavity. Raised.
The cavity filter according to any one of claims 1 to 7, wherein an end of the threaded sleeve close to the cavity is flush with a surface of the cover plate adjacent to the cavity, the thread An end of the sleeve away from the cavity extends beyond the surface of the cover away from the cavity.
A cavity filter according to any one of claims 1 to 3, wherein the cavity filter further comprises a nut that is fixedly sleeved on the tuning screw.
The cavity filter of claim 9 wherein said cavity filter further comprises a gasket disposed over said tuning screw and between said nut and said cover.
The cavity filter according to any one of claims 1 to 3, wherein the cavity comprises a bottom surface and a side wall perpendicular to the bottom surface, the resonance rod is fixed to the bottom surface and the resonance The rod has an upper opening that faces the tuning screw and has an inner diameter that is greater than the outer diameter of the tuning screw.
The cavity filter according to claim 11, wherein the bottom surface has a boss, the resonant rod has a lower opening facing the bottom surface, and the lower opening is sleeved on the boss, and The tuning rod is fixed to the boss by a screw.
The cavity filter of claim 11 wherein said upper opening is cylindrical and concentric with said tuning screw.
The cavity filter according to claim 1, wherein the between the toothless region and the internal thread region satisfy: 0 < D1 - D2 < 0.5 mm, wherein D1 is the edentulous region The inner diameter, D2, is the inner diameter of the internally threaded region.