CN113497315A

CN113497315A - Filter and communication equipment

Info

Publication number: CN113497315A
Application number: CN202010270843.9A
Authority: CN
Inventors: 陈砚昌
Original assignee: Shenzhen Tatfook Technology Co Ltd
Current assignee: Shenzhen Tatfook Technology Co Ltd
Priority date: 2020-04-08
Filing date: 2020-04-08
Publication date: 2021-10-12
Anticipated expiration: 2040-04-08
Also published as: CN113497315B

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 capacitive cross coupling is respectively performed between a third filter cavity and a sixth filter cavity and between a fourth filter cavity and the sixth filter cavity in the eight filter cavities to form two capacitive coupling zeros of the filter; inductively cross-coupling the sixth filtering cavity and the eighth filtering cavity in the eight filtering cavities to form an inductive coupling zero point of the filter; wherein the bandwidth range of the filter is 1884MHz-1916 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 capacitive cross coupling is respectively performed between a third filter cavity and a sixth filter cavity and between a fourth filter cavity and the sixth filter cavity in the eight filter cavities to form two capacitive coupling zeros of the filter; inductively cross-coupling a sixth filtering cavity and an eighth filtering cavity of the eight filtering cavities to form an inductive coupling zero point of the filter; wherein the bandwidth of the filter is in the range of 1884MHz-1916 MHz.

Optionally, the second to seventh filter cavities and the eighth filter cavity of the eight filter cavities are divided into two rows arranged along the second direction; a second filtering cavity, a third filtering cavity and a fourth filtering cavity of the eight filtering cavities are in a row and are sequentially arranged along the first direction; the fifth filtering cavity, the sixth filtering cavity and the eighth filtering cavity in the eight filtering cavities are in a row and are sequentially arranged along the first direction; a first filtering cavity, a second filtering cavity, an eighth filtering cavity and a seventh filtering cavity in the eight filtering cavities are arranged in a straight line; a projection of a center of the seventh filter cavity in the first direction is located between a projection of a center of the sixth filter cavity and a projection of a center of the eighth filter cavity in the first direction; the projection of the center of the eighth filter cavity in the first direction is located between the projection of the center of the third filter cavity and the projection of the center of the second filter cavity in the first direction. The second filtering cavity, the seventh filtering cavity and the eighth filtering cavity of the eight filtering cavities are divided into two rows arranged along the second direction, and each row of filtering cavities are arranged along the first direction, so that the filter can be prevented from being overlarge in size along the first direction and the second direction; and the two rows of filter cavities are arranged in a staggered manner, so that the rows of cavities of the filter are regular, the processing is convenient, and the volume of the filter is reduced.

Optionally, a first window is disposed between the sixth filtering cavity and the eighth filtering cavity; and flying rods are arranged between the third filtering cavity and the sixth filtering cavity and between the fourth filtering cavity and the sixth filtering cavity. And the inductive cross coupling is realized through the first window, and the inductive cross coupling is realized through the flying bar.

Optionally, the flying bar is arranged in a sheet shape, the flying bar includes a first coupling portion, a second coupling portion and a connecting portion, and two ends of the connecting portion are connected to the first coupling portion and the second coupling portion respectively. Simple structure and convenient processing.

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 adjacently arranged filter cavities. And electromagnetic energy is transmitted between two adjacent filter cavities on the main coupling path through the second window.

Optionally, the first window and the second window are respectively provided with an adjusting rod; and reinforcing ribs are respectively arranged on a second window between the first filtering cavity and the second filtering cavity, a second window between the second filtering cavity and the third filtering cavity, and a second window between the third filtering cavity and the fourth filtering cavity. The coupling strength of the first window and the second window is adjusted through the adjusting rod, and 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 U-shaped side wall and a hollow inner cavity formed by the U-shaped side wall; a tuning rod, one end of the tuning rod being disposed within the hollow interior. The resonant frequency of the resonant cavity can be adjusted by adjusting the depth of the tuning rod within the hollow interior.

Optionally, two ends of the U-shaped side wall are bent and extended in a direction away from the hollow inner cavity, so that disc-shaped structures are formed at two ends of the U-shaped side wall, and the disc-shaped structures are arranged in parallel with the bottom of the U-shaped side wall. The disc-shaped structures at the two ends of the U-shaped side wall can increase the signal coupling amount of the resonance rod.

Optionally, the housing is further provided with a mounting post, and the U-shaped side wall is fixed to the mounting post. The resonance rod is fixed on the shell through the mounting column.

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 capacitive cross coupling is respectively performed between a third filter cavity and a sixth filter cavity and between a fourth filter cavity and the sixth filter cavity in the eight filter cavities to form two capacitive coupling zeros of the filter; inductively cross-coupling the sixth filtering cavity and the eighth filtering cavity in the eight filtering cavities to form an inductive coupling zero point of the filter; wherein the bandwidth range of the filter is 1884MHz-1916 MHz. The filter of the embodiment of the application can realize filtering with a bandwidth of 1884MHz-1916 MHz; the filter can realize one inductive coupling zero point, can well control the high-end suppression of the filter bandwidth, obtain better high-end suppression of the bandwidth, can realize two capacitive coupling zero points, can well control the low-end suppression of the filter bandwidth, obtain better low-end suppression of the bandwidth, and therefore can improve 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 fixed seat in the filter of FIG. 1;

FIG. 5 is a schematic diagram of an equivalent circuit configuration of the filter of the embodiment of FIG. 1;

FIG. 6 is a diagram illustrating a simulated structure of the filter of the embodiment of FIG. 1;

fig. 7 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 6, 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 fixed seat in the filter of FIG. 1; FIG. 5 is a schematic diagram of an equivalent circuit configuration of the filter of the embodiment of FIG. 1; fig. 6 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 shell 11, eight filter cavities A1-A8 are sequentially coupled along a main coupling path, and capacitive cross coupling is respectively formed between a third filter cavity A3 and a sixth filter cavity A6 and between a fourth filter cavity A4 and a sixth filter cavity A6 in the eight filter cavities A1-A8 so as to form two capacitive coupling zeros of the filter 10; inductive cross coupling between the sixth filter cavity a6 and the eighth filter cavity A8 of the eight filter cavities a1-A8 to form an inductive coupling zero of the filter 10; wherein the bandwidth of the filter 10 is in the range of 1884MHz-1916 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 1884MHz-1916 MHz; the filter 10 of the present embodiment can realize one inductive coupling zero, can well control the high-end rejection of the bandwidth of the filter 10, obtain a better high-end rejection of the bandwidth, can realize two capacitive coupling zeros, can well control the low-end rejection of the bandwidth of the filter 10, and obtain a better low-end rejection of the bandwidth, and therefore, can improve the stop-band rejection performance of the filter 10.

Alternatively, as shown in fig. 1, the second filter chamber a2 to the eighth filter chamber A8 of the eight filter chambers a1-A8 are divided into two columns arranged in the second direction y; a second filter cavity A2, a third filter cavity A3 and a fourth filter cavity A4 in the eight filter cavities A1-A8 are in a row and are sequentially arranged along a first direction x; a fifth filter cavity A5, a sixth filter cavity A6 and an eighth filter cavity A8 in the eight filter cavities A1-A8 are in a row and are sequentially arranged along a first direction x; the first filter cavity A1, the second filter cavity A2, the eighth filter cavity A8 and the seventh filter cavity A7 of the eight filter cavities A1-A8 are arranged in a straight line; the projection of the centre of the seventh filter chamber a7 in the first direction x is located between the centre of the sixth filter chamber a6 and the projection of the centre of the eighth filter chamber A8 in the first direction x; the projection of the centre of the eighth filter chamber A8 in the first direction x is located between the centre of the third filter chamber A3 and the projection of the centre of the second filter chamber a2 in the first direction x.

As can be seen from the above analysis, the second filter cavity a2 to the seventh filter cavity a7 and the eighth filter cavity A8 of 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 size along 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.

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 U-shaped side wall 210 and a hollow inner cavity 220 formed by the U-shaped side wall 210, and one end of the tuning rod 30 is arranged in the hollow inner cavity 220; the resonant frequency of the resonant 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.

Alternatively, as shown in fig. 3, both ends of the U-shaped sidewall 210 are bent and extended away from the hollow cavity 220 to form a disc-shaped structure 230 at both ends of the U-shaped sidewall 210, and the disc-shaped structure 230 is disposed parallel to the bottom of the U-shaped sidewall 210.

The disk-shaped structures 230 at both ends of the U-shaped 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 the cut 1215 MS. Of course, in other embodiments, the resonant rod may be an M8 or M4 screw rod, and the like, and made of copper or silver.

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 21mm, e.g., 20mm, 19mm, 18mm, etc.

Optionally, as shown in fig. 3, a mounting post 40 is further provided on the housing 11, and the U-shaped 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 U-shaped 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, the present embodiment provides a first window between the sixth filter cavity a6 and the eighth filter cavity A8, through which the inductive cross coupling is realized.

Alternatively, to adjust the coupling strength of the inductive cross-coupling, an adjustment bar 81 may be arranged at the first window.

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 sixth filter chamber a6, and between fourth filter chamber a4 and sixth filter chamber a 6. Inductive cross-coupling is achieved by flying bar 60.

Optionally, as shown in fig. 1 and 4, the flying bar 60 of the present embodiment is in a sheet shape, which is convenient for processing. Specifically, the flying bar 60 includes: the first coupling portion 610, the second coupling portion 620 and the connecting portion 630, two ends of the connecting portion 630 are respectively connected to the first coupling portion 610 and the second coupling portion 620, and the first coupling portion 610 and the second coupling portion 620 are located on the same side of the connecting portion 630. The first coupling part 610, the connecting part 630 and the second coupling part 620 are connected in sequence to form a U-shaped fly rod 60; the first coupling part 610 is coupled to the resonance rod 20 in the third filter cavity A3 such that a coupling capacitance is formed between the first coupling part 610 and the resonance rod 20, and the second coupling part 620 is coupled to the resonance rod 20 in the sixth filter cavity a6 such that a coupling capacitance is formed between the second coupling part 620 and the resonance rod 20.

As shown in fig. 1 and 4, the filter 10 further includes: the fixing seat 70 is disposed on the housing 11, the fixing seat 70 is provided with a through hole (not shown), and the connecting portion 630 penetrates through the through hole to fix the flying bar 60 and the fixing seat 70.

The flying bar 60 of the present embodiment can be implemented by a metal probe, and the fixed seat 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.

In order to improve the coupling strength between two adjacent filter cavities on the main coupling path, reinforcing ribs 80 may be provided at the second windows, for example, the reinforcing ribs 80 may be provided at the second windows between the first filter cavity a1 and the second filter cavity a2, the second windows between the second filter cavity a2 and the third filter cavity A3, and the second windows between the third filter cavity A3 and the fourth filter cavity a4, 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. 5, 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 this embodiment is shown in fig. 6, and it can be seen from fig. 6 that the bandwidth of the filter 10 of this embodiment is about 1884MHz-1916 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 1.885GHz (m1) is-2.398 dB, and the suppression of the frequency point 1.915GHz (m2) is-2.943 dB, so that the filter 10 has the characteristic of small in-band loss (less than 3.5 dB); and the suppression of the frequency point 1.880GHz (m3) is-38.115 dB, and the suppression of the frequency point 1.920GHz (m4) is-49.548 dB, so that the filter 10 has the performance of strong anti-interference capability (the suppression of the 5MHz lower end outside the passband is more than 28dB, and the suppression of the 5MHz high end frequency band outside the passband is more than 42 dB).

The filter 10 of the present embodiment is an 8-order microwave filter applied to a 5G mobile communication system, and has a working frequency band of 879MHz to 916MHz, and has the characteristics of small in-band loss (less than 3.5dB), strong anti-interference capability (the low end 5MHz outside the passband is greater than 28dB suppression, and the high end 5MHz outside the passband is greater than 42dB suppression), small overall size, and light weight.

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 the 1800MHz frequency band.

The present application further provides a communication device, as shown in fig. 7, fig. 7 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 are sequentially coupled along the main coupling path, and capacitive cross coupling is formed between a third filter cavity and a sixth filter cavity and between a fourth filter cavity and the sixth filter cavity in the eight filter cavities respectively to form two capacitive cross coupling zeros of the filter; inductively cross-coupling the sixth filtering cavity and the eighth filtering cavity in the eight filtering cavities to form an inductive coupling zero point of the filter; wherein the bandwidth range of the filter is 1884MHz-1916 MHz. The filter of the embodiment of the application can realize filtering with a bandwidth of 1884MHz-1916 MHz; the filter can realize one inductive coupling zero point, can well control the high-end suppression of the filter bandwidth, obtain better high-end suppression of the bandwidth, can realize two capacitive coupling zero points, can well control the low-end suppression of the filter bandwidth, obtain better low-end suppression of the bandwidth, and therefore can improve 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 capacitive cross coupling is respectively performed between a third filter cavity and a sixth filter cavity and between a fourth filter cavity and the sixth filter cavity in the eight filter cavities to form two capacitive coupling zeros of the filter; inductively cross-coupling a sixth filtering cavity and an eighth filtering cavity of the eight filtering cavities to form an inductive coupling zero point of the filter;

wherein the bandwidth of the filter is in the range of 1884MHz-1916 MHz.

2. The filter according to claim 1, wherein the second through sixth and eighth filter cavities of the eight filter cavities are divided into two columns arranged in the second direction;

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

a first filtering cavity, a second filtering cavity, an eighth filtering cavity and a seventh filtering cavity in the eight filtering cavities are arranged in a straight line;

a projection of a center of the seventh filter cavity in the first direction is located between a projection of a center of the sixth filter cavity and a projection of a center of the eighth filter cavity in the first direction; the projection of the center of the eighth filter cavity in the first direction is located between the projection of the center of the third filter cavity and the projection of the center of the second filter cavity in the first direction.

3. The filter of claim 2, wherein a first window is disposed between the sixth filter cavity and the eighth filter cavity; and flying rods are arranged between the third filtering cavity and the sixth filtering cavity and between the fourth filtering cavity and the sixth filtering cavity.

4. The filter according to claim 3, wherein the flying bar is disposed in a sheet shape, the flying bar includes a first coupling portion, a second coupling portion and a connecting portion, and both ends of the connecting portion are respectively connected to the first coupling portion and the second coupling portion.

5. The filter of claim 3, wherein the eight filter cavities are sequentially arranged adjacently along the main coupling path, and a second window is arranged between any group of the adjacently arranged filter cavities.

6. The filter of claim 5, wherein the first window and the second window are respectively provided with an adjusting rod;

and reinforcing ribs are respectively arranged on a second window between the first filtering cavity and the second filtering cavity, a second window between the second filtering cavity and the third filtering cavity, and a second window between the third filtering cavity and the fourth filtering cavity.

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

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

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

8. The filter according to claim 7, wherein both ends of the U-shaped side wall are bent and extended away from the hollow inner cavity to form a disc-shaped structure at both ends of the U-shaped side wall, and the disc-shaped structure is arranged in parallel with the bottom of the U-shaped side wall.

9. The filter of claim 8, wherein the housing further comprises a mounting post, and wherein the U-shaped sidewall is secured to the mounting post.

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.