CN113675559A

CN113675559A - Filter and communication equipment

Info

Publication number: CN113675559A
Application number: CN202010409098.1A
Authority: CN
Inventors: 陈砚昌
Original assignee: Anhui Tatfook Technology Co Ltd
Current assignee: Anhui Tatfook Technology Co Ltd
Priority date: 2020-05-14
Filing date: 2020-05-14
Publication date: 2021-11-19

Abstract

The application discloses a filter and communication equipment. The filter includes: a housing having a first direction and a second direction perpendicular to each other; the eight filter cavities are arranged on the shell and sequentially coupled along the main coupling path, and a third filter cavity and a fifth filter cavity in the eight filter cavities are capacitively and crossly coupled to form a capacitive coupling zero point of the filter; inductive cross coupling is respectively carried out between a first filtering cavity and a third filtering cavity in the eight filtering cavities and between a fifth filtering cavity and a seventh filtering cavity in the eight filtering cavities to form two inductive coupling zeros of the filter; wherein the bandwidth of the filter is in the range of 702MHz-734 MHz. In this way, the stop-band rejection performance of the filter can be improved.

Description

Filter and communication equipment

Technical Field

The present application relates to the field of communications technologies, and in particular, to a filter and a communications device.

Background

The cavity filter is a key device of a modern mobile communication system and is widely applied to wireless communication base stations and various communication terminals; the cavity filter is composed of a radio frequency connector, a cavity, a cover plate, a plurality of resonator units and a frequency tuning and coupling strength adjusting component, wherein the resonant frequencies of the plurality of resonator units are distributed in the passband range, and the cavity filter has a blocking function on signals outside the resonant frequencies, so that the function of selecting microwave transmission signals is realized; the cavity filter has the advantages of reliable structure, wide filtering frequency band, parasitic pass band far away from a channel, high Q value, stable electrical property, good heat dissipation performance and the like.

The inventor of the present application finds, in long-term research and development work, that the stop band rejection performance of the existing cavity filter is poor.

Disclosure of Invention

The technical problem that this application mainly solved provides a wave filter and communication equipment to improve the stop band rejection performance of wave filter.

In order to solve the technical problem, the application adopts a technical scheme that: a filter is provided. The filter includes: a housing having a first direction and a second direction perpendicular to each other; the eight filter cavities are arranged on the shell and sequentially coupled along a main coupling path, and a third filter cavity and a fifth filter cavity in the eight filter cavities are capacitively and crossly coupled to form a capacitive coupling zero point of the filter; inductively cross-coupling is respectively performed between a first filtering cavity and a third filtering cavity of the eight filtering cavities and between a fifth filtering cavity and a seventh filtering cavity of the eight filtering cavities to form two inductive coupling zeros of the filter; wherein the bandwidth of the filter is in the range of 702MHz-734 MHz.

Optionally, the eight filters are sequentially arranged adjacently along the main coupling path, and the eight filter cavities are divided into two rows arranged along the second direction; the first filtering cavity, the third filtering cavity, the fifth filter and the seventh filtering cavity in the eight filtering cavities are in a row and are sequentially arranged along the first direction; a second filtering cavity, a fourth filtering cavity, a sixth filtering cavity and an eighth filtering cavity in the eight filtering cavities are in a row and are sequentially and adjacently arranged along the first direction; the projection of the center of the second filter cavity in the first direction is positioned between the projection of the center of the first filter cavity and the center of the third filter cavity in the first direction; the distance between the centers of any group of adjacent filter cavities is a preset distance. The eight filter cavities are divided into two rows arranged along the second direction, and each row of filter cavities is arranged along the first direction x, so that the filter can be prevented from being overlarge in size along the first direction and the second direction; the two rows of filter cavities are arranged in a staggered manner, so that the rows of cavities of the filter are regular, and the filter is convenient to process and reduce in volume; and any group of adjacent filter cavities are distributed at equal intervals, so that the processing technology of the filter cavities can be simplified, and the cost is saved.

Optionally, first windows are respectively arranged between the first filter cavity and the third filter cavity, and between the fifth filter cavity and the seventh filter cavity; the first window is provided with an adjusting rod. And realizing the inductive cross coupling through the first window, and adjusting the coupling strength of the inductive cross coupling through an adjusting rod of the first window.

Optionally, a flying rod is arranged between the third filtering cavity and the fifth filtering cavity; the flying bar comprises a first coupling part, a second coupling part and a connecting part, wherein two ends of the connecting part are respectively connected with the first coupling part and the second coupling part. Capacitive cross coupling is achieved through the flying bar.

Optionally, the first coupling portion and the second coupling portion are disposed in a disc shape, the first coupling portion and the second coupling portion are disposed in parallel and perpendicular to the connecting portion, and the connecting portion connects a center of the first coupling portion and a center of the second coupling portion. This structure can increase the coupling area of the first coupling portion and the second coupling portion.

Optionally, the connecting portion includes a first sub-connecting portion, a second sub-connecting portion, and a third sub-connecting portion, wherein one end of the first sub-connecting portion is connected to a center of the first coupling portion, the other end of the first sub-connecting portion is connected to one end of the second sub-connecting portion, the other end of the second sub-connecting portion is connected to one end of the third sub-connecting portion, and the other end of the third sub-connecting portion is connected to a center of the second coupling portion; the size of the first sub-connecting part along the radial direction of the first coupling part is equal to the size of the third sub-connecting part along the radial direction of the first coupling part, and the size of the second sub-connecting part along the radial direction of the first coupling part is smaller than the size of the first sub-connecting part along the radial direction of the first coupling part. The structure can ensure that the size of the middle part of the connecting part is smaller than the sizes of the two ends of the connecting part so as to form a recess, and the stability between the connecting part and the support clamping seat can be increased.

Optionally, the filter further includes a supporting card seat, a through hole is formed in the supporting card seat along an axial direction of the first coupling portion, the second sub-connecting portion is disposed in the through hole in a penetrating manner, the first coupling portion is disposed in the third filtering cavity, and the second coupling portion is disposed in the fifth filtering cavity; the supporting clamping seat is provided with clamping grooves along the surfaces of two sides of the radial direction, and the clamping grooves are clamped with the cavity wall of the third filtering cavity and the cavity wall of the fifth filtering cavity. In this way, the flying bar can be fixed on the support clamping seat, and the support clamping seat is fixed on the cavity wall.

Optionally, the eight filter cavities are sequentially and adjacently arranged along the main coupling path, and a second window is arranged between any group of adjacent filter cavities; and the second window is respectively provided with an adjusting rod and a reinforcing rib. Adjusting the coupling strength between two adjacent filter cavities on the main coupling path by an adjusting rod; the coupling strength between two adjacent filter cavities on the main coupling path is improved through the reinforcing ribs.

Optionally, the filtering cavity is provided with: the resonance rod comprises a side wall and a hollow inner cavity formed by the side wall; a tuning rod, one end of the tuning rod being disposed within the hollow interior; the side walls comprise a first U-shaped side wall, a second U-shaped side wall and a third U-shaped side wall, wherein two ends of the second U-shaped side wall are respectively connected with one end of the first U-shaped side wall and one end of the third U-shaped side wall; wherein the opening direction of the second U-shaped side wall is opposite to the opening direction of the first U-shaped side wall and the opening direction of the third U-shaped side wall. The resonant frequency of the filter cavity can be adjusted by adjusting the depth of the tuning rod in the hollow inner cavity; and the structure can form a tilting tray structure at two ends of the side wall; the tilting disk structures at the two ends of the side wall can increase the signal coupling amount of the resonance rod.

In order to solve the above technical problem, the present application adopts another technical solution: a communication device is provided. The communication equipment comprises an antenna and a radio frequency unit connected with the antenna, wherein the radio frequency unit comprises the filter and is used for filtering radio frequency signals.

The beneficial effect of this application is: different from the prior art, the filter of the embodiment of the application comprises: a housing having a first direction and a second direction perpendicular to each other; the eight filter cavities are arranged on the shell and sequentially coupled along the main coupling path, and a third filter cavity and a fifth filter cavity in the eight filter cavities are capacitively and crossly coupled to form a capacitive coupling zero point of the filter; inductive cross coupling is respectively carried out between a first filtering cavity and a third filtering cavity in the eight filtering cavities and between a fifth filtering cavity and a seventh filtering cavity in the eight filtering cavities to form two inductive coupling zeros of the filter; wherein the bandwidth of the filter is in the range of 702MHz-734 MHz. The filter of the embodiment of the application can realize filtering with a bandwidth of 702MHz-734 MHz; the filter of the embodiment of the application can realize one capacitive coupling zero point, can obtain better bandwidth low-end suppression, can realize two inductive coupling zero points, and can obtain better bandwidth high-end suppression, thereby improving the stop band suppression performance of the filter.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of an embodiment of a filter according to the present application;

FIG. 2 is a schematic diagram of the topology of the filter of the embodiment of FIG. 1;

FIG. 3 is a schematic structural diagram of a tuning rod, a resonant rod and a mounting post assembly of the filter of FIG. 1;

FIG. 4 is a schematic structural diagram of a combination structure of a flying rod and a support clamping seat in the filter of FIG. 1;

FIG. 5 is a schematic structural diagram of a support clamp seat in the filter of the embodiment of FIG. 1;

FIG. 6 is a schematic diagram of an equivalent circuit configuration of the filter of the embodiment of FIG. 1;

FIG. 7 is a diagram illustrating a simulated structure of the filter of the embodiment of FIG. 1;

fig. 8 is a schematic structural diagram of an embodiment of the communication device of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first" and "second" in this application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

The present application first proposes a filter, as shown in fig. 1 to 7, fig. 1 is a schematic structural diagram of an embodiment of the filter of the present application; FIG. 2 is a schematic diagram of the topology of the filter of the embodiment of FIG. 1; FIG. 3 is a schematic structural diagram of a tuning rod, a resonant rod and a mounting post assembly of the filter of FIG. 1; FIG. 4 is a schematic structural diagram of a combination structure of a flying rod and a support clamping seat in the filter of FIG. 1; FIG. 5 is a schematic structural diagram of a support clamp seat in the filter of the embodiment of FIG. 1; FIG. 6 is a schematic diagram of an equivalent circuit configuration of the filter of the embodiment of FIG. 1; fig. 7 is a schematic diagram of a simulation structure of the filter of the embodiment of fig. 1. The filter 10 of the present embodiment includes: a housing 11 and eight filter chambers a1-A8, wherein the housing 11 has a first direction x and a second direction y perpendicular to each other; eight filter cavities a1-A8 are arranged on the housing 11, eight filter cavities a1-A8 are coupled in sequence along a main coupling path, and a third filter cavity A3 and a fifth filter cavity a5 in the eight filter cavities a1-A8 are capacitively cross-coupled to form a capacitive coupling zero of the filter 10; inductive cross coupling is respectively performed between a first filtering cavity A1 and a third filtering cavity A3 in the eight filtering cavities A1-A8 and between a fifth filtering cavity A5 and a seventh filtering cavity A7 in the eight filtering cavities A1-A8 to form two inductive coupling zeros of the filter 10; wherein the bandwidth of the filter 10 ranges from 702MHz to 734 MHz.

Wherein, eight filter chambers A1-A8 include: the filter comprises a first filter cavity A1, a second filter cavity A2, a third filter cavity A3, a fourth filter cavity A4, a fifth filter cavity A5, a sixth filter cavity A6, a seventh filter cavity A7 and an eighth filter cavity A8.

The filter cavity is a communication device for frequency selection and signal suppression, the filter cavity mainly plays a role in frequency control, and the filter cavity is required by the communication device related to frequency transmission and reception.

Different from the prior art, the filter 10 of the embodiment can realize filtering with a bandwidth of 702MHz-734 MHz; the filter 10 of the present embodiment can realize one capacitive coupling zero to obtain better bandwidth low-end rejection, and can realize two inductive coupling zeros to obtain better bandwidth high-end rejection, so that the stop-band rejection performance of the filter 10 can be improved.

Alternatively, as shown in fig. 1, eight filter cavities a1-A8 are arranged adjacently in sequence along the main coupling path, and eight filter cavities a1-A8 are divided into two columns arranged along the second direction y; a first filter cavity A1, a third filter cavity A3, a fifth filter cavity A5 and a seventh filter cavity A7 of the eight filter cavities A1-A8 are in a row and are sequentially arranged along a first direction x; a second filtering cavity A2, a fourth filtering cavity A4, a sixth filtering cavity A6 and an eighth filtering cavity A8 in the eight filtering cavities A1-A8 are in a row and are sequentially arranged along a first direction x; the projection of the centre of the second filter chamber a2 in the first direction x is located between the centre of the first filter chamber a1 and the projection of the centre of the third filter chamber A3 in the first direction x.

From the above analysis, the eight filter cavities a1-A8 are divided into two rows arranged along the second direction y, and each row of filter cavities is arranged along the first direction x, so that the filter 10 can be prevented from being too large in the first direction x and the second direction y; and the two rows of filter cavities are arranged in a staggered manner, so that the rows of cavities of the filter 10 are regular, and the filter is convenient to process and reduce in size.

The distance between the centers of any group of adjacent filter cavities is a preset distance, namely the filter cavities are distributed at equal intervals, so that the processing technology of the filter cavities can be simplified, and the cost is saved.

As shown in fig. 1 and 3, the eight filter cavities a1-A8 are provided with the resonant rod 20 and the tuning rod 30; the resonant rod 20 comprises a side wall 210 and a hollow inner cavity 220 formed by the side wall 210, and one end of the tuning rod 30 is arranged in the hollow inner cavity 220; the resonant frequency of the filter cavity can be adjusted by adjusting the depth of the tuning rod 30 within the hollow interior 220.

The resonant rod 20, the hollow cavity 220 and the tuning rod 30 of the present embodiment are coaxially disposed.

Optionally, as shown in fig. 3, the side wall 210 includes a first U-shaped side wall 211, a second U-shaped side wall 212 and a third U-shaped side wall 213, two ends of the second U-shaped side wall 212 are respectively connected to one end of the first U-shaped side wall 211 and one end of the third U-shaped side wall 213; wherein the opening direction of the second U-shaped sidewall 212 is opposite to the opening direction of the first U-shaped sidewall 211 and the opening direction of the third U-shaped sidewall 213. This structure enables the formation of a tray-flipping structure at both ends of the sidewall 210.

The tilting structure at both ends of the sidewall 210 can increase the signal coupling amount of the resonant bar 20.

Alternatively, the eight filter cavities a1-A8 of the present embodiment may be metal filter cavities, and the resonant rod 20 may be a metal resonant rod.

The material of the resonant rod 20 of the present embodiment may be hpb59-1 lead brass. Of course, in other embodiments, the resonant rod may be an M8 or M4 screw rod, and the like, and is made of silver material, and the like.

The eight filter cavities A1-A8 are the same in size, so that the production is convenient, and the cost is saved. The radii of the eight filter cavities a1-A8 may be less than 29mm, e.g., 28mm, 27mm, 26mm, etc.

Optionally, as shown in fig. 3, a mounting post 40 is further disposed on the housing 11, and the sidewall 210 is fixed on the mounting post 40. The resonant rod 20 is fixed to the housing 11 by a mounting post 40.

Further, a mounting hole (not shown) may be formed in the bottom of the sidewall 210, one end of the mounting post 40 is fixed to the housing 11, and the other end of the mounting post 40 is mounted in the mounting hole, so as to fix the resonant rod 20 to the mounting post 40; the mounting holes may be through holes, the mounting holes may be threaded holes, and the mounting posts 40 are studs. In other embodiments, the mounting hole may also be a blind hole.

Further, the filter 10 further includes a cover plate (not shown) covering the eight filter cavities a1-A8, and the other end of the tuning rod 30 is disposed on the cover plate, wherein the tuning rod 30 may be a metal screw.

The coupling zero is also referred to as a transmission zero. The transmission zero is the transmission function of the filter is equal to zero, namely, the electromagnetic energy cannot pass through the network on the frequency point corresponding to the transmission zero, so that the full isolation effect is achieved, the suppression effect on signals outside the passband is achieved, and the high isolation among the multiple passbands can be better achieved.

Optionally, in this embodiment, first windows are respectively disposed between the first filter cavity a1 and the third filter cavity A3, and between the fifth filter cavity a5 and the seventh filter cavity a7, and the inductive cross coupling is implemented through the first windows.

Alternatively, to adjust the coupling strength of the inductive cross-coupling, an adjustment bar 51 may be arranged at the first window. For example, the adjustment lever 51 is provided at the first window between the first filter chamber a1 and the third filter chamber A3, and at the first window between the fifth filter chamber a5 and the seventh filter chamber a7, respectively.

In other embodiments, to improve the coupling strength of the inductive cross-coupling, a metal coupling rib may be disposed at the first window.

Optionally, a fly rod 60 may be provided between third filter chamber A3 and fifth filter chamber a 5. Capacitive cross coupling is achieved by flying bar 60.

Alternatively, as shown in fig. 1 and 4, the flying bar 60 of the present embodiment includes: the first coupling portion 610, the second coupling portion 620, and the connection portion 630, both ends of the connection portion 630 are connected to the first coupling portion 610 and the second coupling portion 620, respectively.

Alternatively, as shown in fig. 4, the first coupling portion 610 and the second coupling portion 620 are disposed in a disc shape, the first coupling portion 610 and the second coupling portion 620 are disposed in parallel and perpendicular to the connection portion 630, and the connection portion 630 connects a center of the first coupling portion 610 and a center of the second coupling portion 620. This structure can increase the coupling area of the first and

second coupling parts

610 and 620.

Alternatively, as shown in fig. 4, the connection portion 630 includes a first sub-connection portion 631, a second sub-connection portion (not shown), and a third sub-connection portion 632, wherein one end of the first sub-connection portion 631 is connected to the center of the first coupling portion 610, the other end of the first sub-connection portion 631 is connected to one end of the second sub-connection portion, the other end of the second sub-connection portion is connected to one end of the third sub-connection portion 632, and the other end of the third sub-connection portion 632 is connected to the center of the second coupling portion 620; wherein, the dimension of the first sub-connection portion 631 along the radial direction of the first coupling portion 610 is equal to the dimension of the third sub-connection portion 632 along the radial direction of the first coupling portion 610, and the dimension of the second sub-connection portion along the radial direction of the first coupling portion 610 is smaller than the dimension of the first sub-connection portion 631 along the radial direction of the first coupling portion 610. This structure enables the middle portion of the coupling portion 630 to have a smaller size than both ends to form a recess, which can increase stability between the coupling portion 630 and the support socket 70.

Optionally, as shown in fig. 1, 4 and 5, the filter 10 further includes: a support clamping seat 70, wherein a through hole 71 is arranged on the support clamping seat 70 along the axial direction of the first coupling part 610, the second sub-connecting part is arranged in the through hole 71 in a penetrating way, the first coupling part 610 is arranged in the third filtering cavity A3 to form a coupling capacitance with the resonant rod 20 in the third filtering cavity A3, and the second coupling part 620 is arranged in the fifth filtering cavity A5 to form a coupling capacitance with the resonant rod 20 in the fifth filtering cavity A5; clamping grooves 72 are formed in the surfaces of two sides of the support clamping seat 70 in the radial direction, and the clamping grooves 72 are clamped with the cavity wall of the third filter cavity A3 and the cavity wall of the fifth filter cavity A5 so as to fix the flying bar 60 and the support clamping seat 70. In this way, the fly rod 60 can be fixed to the support clamp 70, and the support clamp 70 can be fixed to the cavity wall.

The flying bar 60 of the present embodiment can be implemented by a metal probe, and the support holder 70 is implemented by PTFE or engineering plastic.

As shown in fig. 1, the eight filter cavities a1-A8 are arranged adjacently in sequence along the main coupling path, a second window (not shown) is arranged between any group of adjacent filter cavities, and electromagnetic energy is transmitted between two adjacent filter cavities on the main coupling path through the second window. For example, second windows are respectively disposed between the first filter cavity a1 and the second filter cavity a2, between the second filter cavity a2 and the third filter cavity A3, between the third filter cavity A3 and the fourth filter cavity a4, between the fourth filter cavity a4 and the fifth filter cavity a5, between the fifth filter cavity a5 and the sixth filter cavity A6, between the sixth filter cavity A6 and the seventh filter cavity a7, and between the seventh filter cavity a7 and the eighth filter cavity A8.

The filter 10 of the present embodiment further includes a plurality of adjustment rods 50 and a plurality of reinforcing ribs 80.

To adjust the coupling strength between two adjacent filter cavities on the main coupling path, an adjustment lever 50 may be provided at the second window, for example, a second window between the first filter cavity a1 and the second filter cavity a2, a second window between the second filter cavity a2 and the third filter cavity A3, a second window between the third filter cavity A3 and the fourth filter cavity a4, a second window between the fourth filter cavity a4 and the fifth filter cavity a5, a second window between the fifth filter cavity a5 and the sixth filter cavity A6, a second window between the sixth filter cavity A6 and the seventh filter cavity a7, and a second window between the seventh filter cavity a7 and the eighth filter cavity A8, respectively.

To improve the coupling strength between two adjacent filter cavities on the main coupling path, reinforcing ribs 80 may be provided at the second window, for example, a second window between the first filter cavity a1 and the second filter cavity a2, a second window between the second filter cavity a2 and the third filter cavity A3, a second window between the third filter cavity A3 and the fourth filter cavity a4, a second window between the fourth filter cavity a4 and the fifth filter cavity a5, a second window between the fifth filter cavity a5 and the sixth filter cavity A6, a second window between the sixth filter cavity A6 and the seventh filter cavity a7, and a second window between the seventh filter cavity a7 and the eighth filter cavity A8, respectively.

Further, as shown in fig. 1, the filter 10 of the present embodiment further includes: an input port (not shown) connected to the first filter chamber a1 of the filter 10 and an output port (not shown) connected to the eighth filter chamber A8 of the filter 10.

The input port and the output port are taps, the input port is connected with the resonance rod 20 in the first filter cavity A1, and electromagnetic signals are input into the first filter cavity A1; the output port is connected to the resonant rod 20 in the eighth filter chamber A8, and outputs the electromagnetic signal in the eighth filter chamber A8.

The equivalent circuit of the filter 10 of this embodiment is shown in fig. 6, where the impedance Z1 at the input port is about 50 ohms, and the impedance Z2 at the output port is about 50 ohms; in order to ensure the transmission of electromagnetic signals between the filter cavities a1-A8 of the filter 10, impedance adjusters ZV are required to be respectively arranged between the input port and the first filter cavity a1, between adjacent filter cavities on the main coupling path, between non-cascaded filter cavities forming cross coupling, and between the eighth filter cavity A8 and the output port, so as to realize impedance matching.

The simulation result of the filter 10 of the present embodiment is shown in fig. 7, and it can be known from fig. 7 that the bandwidth of the filter 10 of the present embodiment is about 702MHz-734 MHz; as shown in the frequency band curve S1, there are a low-end coupling zero point a and two high-end coupling zero points b and c; the suppression of the frequency point 703MHz (m1) is-0.963 dB, and the suppression of the frequency point 733MHz (m2) is-1.493 dB, so that the filter 10 has the characteristic of small in-band loss (less than 1.55 dB); and the suppression of the frequency point 693MHz (m3) is-59.189 dB, the suppression of the frequency point 743MHz (m4) is-51.951 dB, and the suppression of the frequency point 758MHz (m5) is-85.143 dB, so that the filter 10 has the performance of strong anti-interference capability (the suppression of 10MHz outside a passband is more than 45dB, and the suppression of 25MHz frequency band outside the passband is more than 80 dB).

The filter 10 of the embodiment is an 8-order microwave filter applied to a 5G mobile communication system, the working frequency band of the filter is 702MHz-734, and the filter has the characteristics of small in-band loss (less than 4.55dB) and strong anti-interference capability (the suppression of the frequency band of 25MHz outside a pass band is greater than 45dB, and the suppression of the frequency band of 10MHz outside the pass band is greater than 80 dB).

The filter of the embodiment of the application has low loss, and can ensure low energy consumption of the communication module; the filter is designed by combining 8-order resonant cavities, and a coupling zero structure is introduced, so that the filter has strong anti-interference capability and can ensure that a communication system is not interfered by stray signals; the filter has the advantages of simple design scheme, low cost, good structure and electrical property stability; the filter can meet the use of the current latest 5G mobile communication system, and the filter mainly relates to a 700MHz frequency band.

The present application further provides a communication device, as shown in fig. 8, fig. 8 is a schematic structural diagram of an embodiment of the communication device of the present application. The communication device of the present embodiment includes an antenna 32 and a radio frequency unit 31 connected to the antenna 32, the radio frequency unit 31 includes a filter 10 as shown in the above-mentioned embodiment, and the filter 10 is used for filtering a radio frequency signal.

In other embodiments, the rf Unit 31 may be integrated with the Antenna 32 to form an Active Antenna Unit (AAU).

Different from the prior art, the filter of the embodiment of the application comprises: a housing having a first direction and a second direction perpendicular to each other; the eight filter cavities are arranged on the shell and sequentially coupled along the main coupling path, and a third filter cavity and a fifth filter cavity in the eight filter cavities are capacitively and crossly coupled to form a capacitive coupling zero point of the filter; inductive cross coupling is respectively carried out between a first filtering cavity and a third filtering cavity in the eight filtering cavities and between a fifth filtering cavity and a seventh filtering cavity in the eight filtering cavities to form two inductive coupling zeros of the filter; wherein the bandwidth of the filter is in the range of 702MHz-734 MHz. The filter of the embodiment of the application can realize filtering with a bandwidth of 702MHz-734 MHz; the filter of the embodiment of the application can realize one capacitive coupling zero point, can obtain better bandwidth low-end suppression, can realize two inductive coupling zero points, and can obtain better bandwidth high-end suppression, thereby improving the stop band suppression performance of the filter.

The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. A filter, characterized in that the filter comprises:

a housing having a first direction and a second direction perpendicular to each other;

the eight filter cavities are arranged on the shell and sequentially coupled along a main coupling path, and a third filter cavity and a fifth filter cavity in the eight filter cavities are capacitively and crossly coupled to form a capacitive coupling zero point of the filter; inductively cross-coupling is respectively performed between a first filtering cavity and a third filtering cavity of the eight filtering cavities and between a fifth filtering cavity and a seventh filtering cavity of the eight filtering cavities to form two inductive coupling zeros of the filter;

wherein the bandwidth of the filter is in the range of 702MHz-734 MHz.

2. The filter of claim 1, wherein the eight filters are arranged adjacent to each other in sequence along the main coupling path, and the eight filter cavities are divided into two columns arranged along the second direction;

the first filtering cavity, the third filtering cavity, the fifth filter and the seventh filtering cavity in the eight filtering cavities are in a row and are sequentially arranged along the first direction; a second filtering cavity, a fourth filtering cavity, a sixth filtering cavity and an eighth filtering cavity in the eight filtering cavities are in a row and are sequentially and adjacently arranged along the first direction;

the projection of the center of the second filter cavity in the first direction is positioned between the projection of the center of the first filter cavity and the center of the third filter cavity in the first direction;

the distance between the centers of any group of adjacent filter cavities is a preset distance.

3. The filter according to claim 2, wherein a first window is respectively arranged between the first filter cavity and the third filter cavity and between the fifth filter cavity and the seventh filter cavity;

the first window is provided with an adjusting rod.

4. The filter of claim 2, wherein a fly rod is arranged between the third filter cavity and the fifth filter cavity;

the flying bar comprises a first coupling part, a second coupling part and a connecting part, wherein two ends of the connecting part are respectively connected with the first coupling part and the second coupling part.

5. The filter according to claim 4, wherein the first coupling portion and the second coupling portion are disposed in a shape of a disk, the first coupling portion is disposed parallel to the second coupling portion and perpendicular to the connecting portion, and the connecting portion connects a center of the first coupling portion and a center of the second coupling portion.

6. The filter according to claim 5, wherein the connection portion comprises a first sub-connection portion, a second sub-connection portion and a third sub-connection portion, wherein one end of the first sub-connection portion is connected to a center of the first coupling portion, the other end of the first sub-connection portion is connected to one end of the second sub-connection portion, the other end of the second sub-connection portion is connected to one end of the third sub-connection portion, and the other end of the third sub-connection portion is connected to a center of the second coupling portion;

the size of the first sub-connecting part along the radial direction of the first coupling part is equal to the size of the third sub-connecting part along the radial direction of the first coupling part, and the size of the second sub-connecting part along the radial direction of the first coupling part is smaller than the size of the first sub-connecting part along the radial direction of the first coupling part.

7. The filter according to claim 6, further comprising a supporting card seat, wherein a through hole is formed in the supporting card seat along an axial direction of the first coupling portion, the second sub-connecting portion is disposed in the through hole in a penetrating manner, the first coupling portion is disposed in the third filtering cavity, and the second coupling portion is disposed in the fifth filtering cavity;

the supporting clamping seat is provided with clamping grooves along the surfaces of two sides of the radial direction, and the clamping grooves are clamped with the cavity wall of the third filtering cavity and the cavity wall of the fifth filtering cavity.

8. The filter according to claim 2, wherein the eight filter cavities are arranged adjacently in sequence along the main coupling path, and a second window is arranged between any group of the filter cavities arranged adjacently;

and the second window is respectively provided with an adjusting rod and a reinforcing rib.

9. The filter of claim 1, wherein the filter cavity is provided with:

the resonance rod comprises a side wall and a hollow inner cavity formed by the side wall;

a tuning rod, one end of the tuning rod being disposed within the hollow interior;

the side walls comprise a first U-shaped side wall, a second U-shaped side wall and a third U-shaped side wall, wherein two ends of the second U-shaped side wall are respectively connected with one end of the first U-shaped side wall and one end of the third U-shaped side wall; wherein the opening direction of the second U-shaped side wall is opposite to the opening direction of the first U-shaped side wall and the opening direction of the third U-shaped side wall.

10. A communication device, characterized in that the communication device comprises an antenna and a radio frequency unit connected to the antenna, the radio frequency unit comprising a filter according to any of claims 1-9 for filtering a radio frequency signal.