CN110767969A

CN110767969A - Cavity filter

Info

Publication number: CN110767969A
Application number: CN201810843649.8A
Authority: CN
Inventors: 周虹; 沈楠; 毛胤电; 余万里
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2018-07-27
Filing date: 2018-07-27
Publication date: 2020-02-07
Also published as: WO2020019867A1

Abstract

The embodiment of the invention discloses a cavity filter, and belongs to the technical field of communication electronics. The cavity filter comprises a shell, a resonator and a resonator carrier, wherein the resonator carrier is fixed at the bottom of the shell, the resonator is arranged in the shell and fixed on the resonator carrier, and the resonant frequency point of the cavity filter is determined by adjusting the length of the resonator extending into the shell. By adopting the embodiment of the invention, the tuning screw rod and the locking nut on the side of the cover plate are eliminated, so that the cavity filter has lighter weight and smaller volume; and because the tuning region no longer is limited to the apron side, but adjusts to the cavity bottom, and the apron is the airtight cavity effect of pure promptly, stretches into the inside length of cavity through the syntonizer of adjustment cavity bottom, and then adjusts resonance frequency point scope, has increased the tuning space scope, compares traditional adjusting resonance frequency point at the apron side, and frequency tuning is more sensitive, and adjustable frequency range is bigger.

Description

Cavity filter

Technical Field

The embodiment of the invention relates to the technical field of communication electronics, in particular to a cavity filter.

Background

Commercial requirements of a 5G Massive MIMO (large-scale Multiple-Input Multiple-Output) technology for mobile communication become larger and larger, and as the number of channels increases, the size and weight of a base station system architecture also increase. However, considering the limited machining size of the structural member and the difficulty of outfield construction, the size and weight of the base station system framework cannot be increased linearly, and the requirements for miniaturization and light weight are more and more urgent. The cavity filter is used as a passive module of the base station system framework and used for selecting communication signal frequency and filtering out clutter or interference signals outside the communication signal frequency, and the size and weight of the cavity filter directly influence the development of miniaturization and light weight of the base station system framework.

A single-cavity structure of a cavity filter in the prior art is shown in fig. 1, and comprises a cavity 11, a cover plate 12, a tuning screw 13, a lock nut 14, and a resonator 15. The resonator 15 is fixed at the bottom of the cavity 11 through a locking screw, and the tuning screw 13 penetrates through the cover plate 12 to extend into the cavity 11 and is locked on the cover plate through a locking nut 14. The tuning screw 13 is rotated the length deep inside the cavity 11 to accomplish frequency tuning. The cavity filter is debugged from the side of the cover plate 12, has more internal components, complex structure and larger weight and volume, and can not meet the requirements of miniaturization and light weight of a base station system framework.

Disclosure of Invention

In view of this, an object of the embodiments of the present invention is to provide a cavity filter, so as to solve the problems that in the prior art, there are many internal components, the structure is complex, the weight and the volume are both large, and the requirements of miniaturization and light weight of a base station system architecture cannot be met.

The technical scheme adopted by the embodiment of the invention for solving the technical problems is as follows:

according to a first aspect of the embodiments of the present invention, there is provided a cavity filter, including a housing, a resonator, and a resonator carrier, where the resonator carrier is fixed at the bottom of the housing, the resonator is disposed in the housing and fixed on the resonator carrier, and a resonant frequency point of the cavity filter is determined by adjusting a length of the resonator extending into the housing.

According to the cavity filter disclosed by the embodiment of the invention, a cover plate side tuning screw and a locking nut are omitted, so that the cavity filter is lighter in weight and smaller in volume; and because the tuning region no longer is limited to the apron side, but adjusts to the cavity bottom, and the apron is the airtight cavity effect of pure promptly, stretches into the inside length of cavity through the syntonizer of adjustment cavity bottom, and then adjusts resonance frequency point scope, has increased the tuning space scope, compares traditional adjusting resonance frequency point at the apron side, and frequency tuning is more sensitive, and adjustable frequency range is bigger.

Drawings

FIG. 1 is a schematic structural diagram of a single cavity of a cavity filter in the prior art;

fig. 2 is a schematic structural diagram of a single cavity of a cavity filter according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a single cavity of another cavity filter according to a second embodiment of the present invention;

FIG. 4 is a side and top view of the resonator carrier of FIG. 3;

FIG. 5 is a schematic view of a second embodiment of the present invention with a spacer;

fig. 6 is a schematic structural diagram of a single cavity of another cavity filter according to a third embodiment of the present invention.

The implementation, functional features and advantages of the objects of the embodiments of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the embodiments of the present invention clearer and more obvious, the embodiments of the present invention are described in further detail below with reference to the accompanying drawings and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the invention and are not limiting of the embodiments of the invention.

Referring to fig. 2, a single cavity of the cavity filter includes a housing 21, a resonator 22, and a resonator carrier 23, where the resonator carrier 23 is fixed at the bottom of the housing 21, the resonator 22 is disposed in the housing 21 and fixed on the resonator carrier 23, and a resonant frequency point of the cavity filter is determined by adjusting a length of the resonator 22 extending into the housing 23.

The housing 21 includes a cover 211 and a cavity 212. The upper opening of the cavity 212, the thickness of the sidewall and the bottom of the cavity are set according to the performance reliability of the cavity filter, and the specific material characteristics can be selected according to actual requirements. The cover plate 211 is disposed on an upper end surface of the cavity 212, and is used for sealing the cavity 212 and preventing signal leakage.

In practical applications, the cover plate 211 may be fixed on the cavity 212 by screws, or may be fixed on the cavity 212 by a welding method, such as laser welding, solder paste welding, or high-frequency induction welding.

In practical applications, the resonator 22 and the resonator carrier 23 may be fixed together by riveting or screwing, or may be fixed together by external welding, such as laser welding, solder paste welding, or high frequency induction welding.

The mating area of the resonator 22 with the resonator carrier 23 may be of a male-female design (as referred to with locating posts and holes) for coarse positioning during the interaction.

In practical applications, the resonator carrier 23 and the cavity 212 may be fixed by riveting or screwing, or by welding, such as laser welding, solder paste welding or high-frequency induction welding;

the resonator carrier 23 may be made of stainless steel, brass, or the like, and may have a material selected according to hardness, elasticity, expansion coefficient, and heat dissipation requirements. The resonator carrier 23 may be made of a material or have a structural design that facilitates heat dissipation, thereby reducing the temperature inside the cavity and optimizing the heat dissipation capacity.

To further ensure good grounding, the resonator carrier 23 may be provided with a conductive plating on the surface, which may be a silver plating, or a copper-silver hybrid plating, or the like.

In practical applications, the shapes and materials of the cavity 212, the cover 211, and the resonator 22 are not limited, and may be aluminum oxide or plastic. In order to ensure good electrical performance characteristics, conductive plating may be provided on the cavity 212, the cover plate 211, and the inner region of the resonator 22, and the conductive plating may be silver plating, or copper-silver mixed plating.

In order to produce a good tuning effect, the central axes of the cavity 212, the resonator 22 and the resonator carrier 23 coincide with each other, i.e. their centers are on the same central axis.

In practical application, in order to avoid metal chips falling into the bottom in the production process and enhance signal isolation, the outer side of the bottom of the cavity body can be pasted with a spacer, the spacer can be tinfoil paper, plastic films with other back adhesives and the like, and the spacer can meet the characteristic that the filter is not warped and not fallen after being baked for a long time in a high-temperature working state.

In practice, the bottom of the resonator 22 and the resonator carrier 23 may or may not be flush with the outer edge of the bottom of the housing 21.

Compared with the prior art, the cavity filter of the embodiment omits a cover plate side tuning screw rod and a locking nut, so that the cavity filter has lighter weight and smaller volume; and because the tuning region no longer is limited to the apron side, but adjusts to the cavity bottom, and the apron is the airtight cavity effect of pure promptly, stretches into the inside length of cavity through the syntonizer of adjustment cavity bottom, and then adjusts resonance frequency point scope, has increased the tuning space scope, compares traditional adjusting resonance frequency point at the apron side, and frequency tuning is more sensitive, and adjustable frequency range is bigger. On the other hand, the resonator is fixed at the bottom of the cavity through the resonator carrier, the assembly form is more flexible, and compared with the mode that the resonator is fixed at the bottom of the cavity in an integrated die-casting or stamping mode, the rejection rate is reduced.

On the basis of the foregoing embodiments, the second embodiment of the present invention provides another cavity filter, referring to fig. 3 to 4, the cavity filter may include a plurality of cavities, wherein each single cavity includes: a shell 31, a resonator 32 and a resonator carrier 33, wherein the resonator carrier 33 is fixed at the bottom of the shell 31, the resonator 32 is arranged in the shell 31 and fixed on the resonator carrier 33, and the resonance frequency point of the cavity filter is determined by the length adjustment of the resonator 22 extending into the shell 33.

The housing 31 includes a cover 311 and a cavity 312. The upper end of the cavity 312 is open, a T-shaped rib is arranged on the side wall of the cavity 312, and a tin melting groove 3121 is left at the upper end of the T-shaped rib. The cover plate 211 is disposed on an upper end surface of the cavity 212 and is used for sealing the cavity 212 and preventing signal leakage.

The resonator carrier 33 is provided with a fixed edge 331 and a deformation zone 332, the deformation zone 332 and the cross section of the fixed edge 331 forming an "n" shaped structure. A plurality of connecting pieces 333 are disposed between the deformation region 332 and the fixing edge 331, the fixing edge 331 is at the bottom of the cavity 312, the deformation region 332 faces the inside of the cavity 312, and the resonator 32 is fixed on the deformation region 332.

The "n" shaped structure is formed by the connection piece 333 being drawn toward the inside of the housing 31 by tensile deformation when the deformation region 332 is struck by an external device during the manufacturing process of the cavity filter. In this embodiment, in order to ensure good deformation of the connecting pieces, the thickness of the deformation region 332 can be thinner than that of the fixing edge 331, and meanwhile, the connecting pieces 333 can be hollowed out in pairs, which is not only beneficial to better deformation, but also beneficial to excessive deformation adjustment when the deformation is excessive, for example, when the deformation region 332 extends into the cavity 312 is excessive, the deformation region 332 is pulled outwards by the hollowed part of the tool extending into the connecting pieces, so as to adjust the internal deformation of the deformation region extending into the cavity 312. In practice, one or more hollow holes may be provided in the deformation region 332 to facilitate adjustment of excess deformation when excess deformation occurs. When an external device strikes the deformation zone 332, the shape of the connecting piece 333 is deformed and elongated, so that the deformation zone 332 extends into the cavity 312.

In practical application, the size and density of the connecting sheet 333 need to be designed in consideration of deformation amount, and after the knocking deformation is completed, the deformation area 332 will not be changed due to the weight of a single resonator 32 during transportation.

In this embodiment, the fixing edge 331 of the resonator carrier 33 is fixed at the bottom of the cavity 312 by means of press-riveting, the resonator 32 is fixed on the resonator carrier 33 by means of welding, and in order to crack the welding position between the resonator 32 and the resonator carrier 33 during press-riveting, the welding area is disposed on a boss 334 of the deformation area 332 (see fig. 4), and a positioning groove is disposed at the top end of the boss 334.

The resonator 32 is provided with a bottom pillar 321, and the bottom of the bottom pillar 321 is provided with a guide pillar corresponding to the positioning groove of the boss.

The cavity filter of the present embodiment can be mounted in the following manner:

firstly, the end face of the guide post at the bottom of the resonator 321 is brushed with solder paste, the resonator carrier 33 is roughly positioned with the resonator 321 through the positioning groove on the boss 334, the outer part of the tool fixture is pressed in place, and the tool fixture is placed into welding equipment with set temperature and time.

After the welding is completed, the fixing edge 331 of the resonator carrier 33 to which the resonator 32 is fixed is press-riveted to the bottom of the cavity 312 by using a tool holder.

Then, the cover 311 is installed. And brushing solder paste on the cover plate 311 by using a steel mesh (the melting point of the solder paste is far lower than that of the solder paste selected by the bottom column welding of the resonator), reversely buckling the cavity 312 with the internal assembly completed on the cover plate 311, pressing the cover plate in place by using a tool clamp, and putting the cover plate into welding equipment with set temperature and time to complete welding.

In practical application, the cover plate 311 may be provided with air holes, and the tin-containing groove 3121 on the cavity 312 may be omitted.

In this embodiment, the single chamber of cavity filter only needs to carry out a lap welding, accomplishes the syntonizer welding of higher temperature in the outside, can avoid the cavity silvered film to be heated the easy yellow problem. If the silver plating technology is mature, the single cavity can be added with one more welding.

Referring to fig. 5, in order to avoid the falling of metal chips into the bottom deformation region 332 during the production process and to enhance signal isolation, a spacer 34 may be adhered to the outer side of the bottom of the cavity, and the spacer 34 may be a tin foil paper, or other adhesive-backed plastic film, etc., as long as the spacer satisfies the characteristics of no warpage and no falling after being baked for a long time under the high-temperature working state of the filter.

The cavity filter of the embodiment cancels the tuning screw rod and the locking nut on the cover plate side, so that the cavity filter has lighter weight and smaller volume; and because the tuning region no longer is limited to the apron side, but adjusts to the cavity bottom, and the apron is the airtight cavity effect of pure promptly, stretches into the inside length of cavity through the syntonizer of adjustment cavity bottom, and then adjusts resonance frequency point scope, has increased the tuning space scope, compares traditional adjusting resonance frequency point at the apron side, and frequency tuning is more sensitive, and adjustable frequency range is bigger. On the other hand, the resonator is fixed at the bottom of the cavity through the resonator carrier, the assembly form is more flexible, and compared with the mode that the resonator is fixed at the bottom of the cavity in an integrated die-casting or stamping mode, the rejection rate is reduced.

On the basis of the foregoing embodiment, a third embodiment of the present invention provides another cavity filter, where a schematic structural diagram of a single cavity of the cavity filter is shown in fig. 6, and the cavity filter includes: a shell 61, a resonator 62 and a resonator carrier 63, wherein the resonator carrier 63 is fixed at the bottom of the shell 61, the resonator 62 is arranged in the shell 61 and fixed on the resonator carrier 63, and the resonance frequency point of the cavity filter is determined by adjusting the length of the resonator 62 extending into the shell 63.

The housing includes a cover 611 and a cavity 612. The upper end of the cavity 612 is open, a T-shaped separating rib is arranged on the side wall of the cavity 612, and a tin melting groove is reserved at the upper end of the T-shaped separating rib. The cover plate 611 is disposed on the upper end surface of the cavity 612, and is used for sealing the cavity 612 and preventing signal leakage.

The resonator carrier 63 has an "i" shaped longitudinal cross-sectional profile with a threaded through bore along the longitudinal axis. The concave part of the I-shaped outline forms a clamping groove which is matched with the clamping position at the bottom of the cavity 62.

The resonator 62 is provided with a bottom pillar 621, and the bottom pillar 621 is provided with a rotary thread corresponding to the threaded through hole of the resonator carrier 63, and the rotary thread can realize self-locking with the threaded through hole of the resonator carrier 63. The filter 62 is fixed to the resonator carrier 63 by the bottom pillar 621.

first, the resonator carrier 63 is clinched to the bottom of the cavity 612.

The post 621 of the resonator 62 is then passed into the cavity 612 with selected threads thereon engaging the threaded through-hole of the resonator carrier 63 and with the post 621 extending from the resonator carrier 63. The length of the resonator 62 extending into the cavity 612 is adjusted by rotating the bottom pillar 621 from the outside of the cavity 612, so that the distance between the resonator 62 and the cover plate 611 is adjusted, and the resonance frequency point is adjusted. After the frequency is tuned in place, the portion of the resonator 62 extending beyond the resonator carrier is trimmed to remain flush with the bottom of the cavity 612.

Finally, a cover plate 611 is installed. The cover plate 611 is brushed with solder paste through a steel mesh (the melting point of the solder paste is far lower than that of solder paste selected by welding the bottom columns of the resonators), the cavity with the assembled inner part is reversely buckled on the cover plate, a tool clamp is adopted to be pressed in place, and the cover plate is placed into welding equipment with set temperature and time to complete welding.

In practical application, the cover plate 611 may also be provided with air holes, and at this time, the tin-containing groove on the cavity 612 may be omitted.

In this embodiment, it is assumed that the size of a single cavity of the cavity filter is: the diameter is 10mm and the height is 10.5mm, tuning is carried out through the bottom pillar 621 of the resonator 62, so that the distance d between the top end of the resonator 62 and the cover plate is set to be 0.5mm, and the single-cavity resonance frequency point can reach 3.4 Ghz. On the premise of the same size of the single cavity and the resonator, if the single-cavity structure scheme of fig. 1 is adopted, the resonance frequency point is about 3.8GHz, and the Q value of the single-cavity quality factor is also poorer. If 3.4GHz is to be reached, the size of a single cavity of the cavity filter in FIG. 1 needs to be increased by more than 2mm in the height direction for nut locking, namely the size of the single cavity: diameter 10mm and height 12.5 mm. Therefore, under the condition that the resonance frequency points are the same, the single cavity adopting the embodiment of the invention has smaller size and lighter weight. And because the tuning region no longer is limited to the cover plate side, but is adjusted to the bottom of the cavity 612, namely the cover plate 611 only has the effect of a pure closed cavity, the resonator 62 at the bottom of the cavity 612 is adjusted to extend into the cavity 612, so that the range of the resonant frequency point is adjusted, the tuning space range is enlarged, and compared with the traditional method of adjusting the resonant frequency point at the cover plate side, the frequency tuning is more sensitive, and the adjustable frequency range is larger. On the other hand, the resonator is fixed at the bottom of the cavity through the resonator carrier, the assembly form is more flexible, and compared with the mode that the resonator is fixed at the bottom of the cavity in an integrated die-casting or stamping mode, the rejection rate is reduced.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, and are not intended to limit the scope of the embodiments of the invention. Any modifications, equivalents and improvements that may occur to those skilled in the art without departing from the scope and spirit of the embodiments of the present invention are intended to be within the scope of the claims of the embodiments of the present invention.

Claims

1. The cavity filter is characterized by comprising a shell, a resonator and a resonator carrier, wherein the resonator carrier is fixed at the bottom of the shell, the resonator is arranged in the shell and fixed on the resonator carrier, and the resonant frequency point of the cavity filter is determined by adjusting the length of the resonator extending into the shell.

2. The cavity filter of claim 1, wherein the resonator carrier is provided with a fixing edge and a deformation region, the deformation region and the fixing edge form an "n" shaped structure in cross section, the fixing edge is fixed at the bottom of the housing, the deformation region faces the inside of the housing, and the resonator is fixed on the deformation region.

3. The cavity filter of claim 2, wherein a plurality of tabs are provided between the deformation region and the fixed edge.

4. The cavity filter of claim 1, wherein said resonator carrier is provided with a threaded through hole, said filter is provided with a bottom post, said bottom post is provided with a rotating thread that mates with said threaded through hole, and said filter is secured to said resonator carrier by said bottom post.

5. The cavity filter of claim 4, wherein the resonators and the bottom of the resonator carrier are flush or non-flush with an outside edge of the bottom of the housing.

6. The cavity filter of any one of claims 1 to 5, wherein the bottom of the housing is provided with spacers on the outside.

7. The cavity filter of any one of claims 1 to 5, wherein the resonator carrier surface is provided with a conductive plating.

8. The cavity filter of any one of claims 1 to 5, wherein central axes of the housing, resonator and resonator carrier coincide with each other.