CN113922024A

CN113922024A - Filter and communication equipment

Info

Publication number: CN113922024A
Application number: CN202010658507.1A
Authority: CN
Inventors: 贺从虎; 马基良
Original assignee: Anhui Tatfook Technology Co Ltd
Current assignee: Anhui Tatfook Technology Co Ltd
Priority date: 2020-07-09
Filing date: 2020-07-09
Publication date: 2022-01-11

Abstract

The application discloses wave filter and communication equipment, this wave filter includes: the filter comprises a shell and a filtering branch; the shell is provided with a first direction and a second direction which are perpendicular to each other; the filtering branch is arranged on the shell and consists of nine filtering cavities which are coupled in sequence, and partial filtering cavities of the filtering branch are in cross coupling to form a cross coupling zero point of the filtering branch; the nine filter cavities of the filter branch circuit are divided into two rows arranged along the first direction. By the method, the out-of-band rejection performance of the filter can be improved, and the production cost of the filter can be reduced.

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

In a mobile communication system, a desired signal is modulated to form a modulated signal, the modulated signal is carried on a high-frequency carrier signal, the modulated signal is transmitted to the air through a transmitting antenna, the signal in the air is received through a receiving antenna, and the signal received by the receiving antenna does not include the desired signal but also includes harmonics and noise signals of other frequencies. The signal received by the receiving antenna needs to be filtered by a filter to remove unnecessary harmonic and noise signals. Therefore, the designed filter must precisely control its upper and lower limit frequencies to maintain high isolation from signals outside the pass band.

The inventor of the application finds that the setting of the coupling zero point of the existing filter is not reasonable in long-term research and development work, so that the characteristics of the filter such as out-of-band rejection are poor, the high isolation from out-of-band signals is difficult to achieve, and the size is large.

Disclosure of Invention

The present application provides a filter and a communication device to solve the above technical problems.

In order to solve the technical problem, the application adopts a technical scheme that: the filter comprises a shell and a filtering branch; the shell is provided with a first direction and a second direction which are perpendicular to each other; the filtering branch is arranged on the shell and consists of nine filtering cavities which are sequentially coupled, and partial filtering cavities are in cross coupling to form a cross coupling zero point of the filtering branch; the nine filter cavities of the filter branch circuit are divided into two rows arranged along the first direction.

Furthermore, a first filtering cavity, a second filtering cavity, a fifth filtering cavity, a sixth filtering cavity and a ninth filtering cavity of the filtering branch are in a row and are sequentially arranged along a second direction;

the third filtering cavity, the fourth filtering cavity, the seventh filtering cavity and the eighth filtering cavity of the filtering branch are in a row and are sequentially arranged along the second direction;

capacitive cross coupling elements are respectively arranged between the second filter cavity and the fourth filter cavity of the filter branch circuit, between the second filter cavity and the fifth filter cavity of the filter branch circuit, between the sixth filter cavity and the eighth filter cavity of the filter branch circuit, and between the sixth filter cavity and the ninth filter cavity of the filter branch circuit, so as to form two capacitive cross coupling zero points at the high end of the pass band of the filter branch circuit and two capacitive cross coupling zero points at the low end of the pass band; the pass band of the filtering branch circuit ranges from 2575MHz to 2615 MHz.

Furthermore, a second filter cavity of the filter branch is respectively adjacent to the first filter cavity, the third filter cavity, the fourth filter cavity and the fifth filter cavity of the filter branch;

and the sixth filtering cavity of the filtering branch is respectively adjacent to the fifth filtering cavity, the seventh filtering cavity, the eighth filtering cavity and the ninth filtering cavity of the filtering branch.

Further, the capacitive cross coupling element comprises a supporting clamping seat and a flying rod, the supporting clamping seat is respectively arranged between the second filtering cavity and the fourth filtering cavity, between the second filtering cavity and the fifth filtering cavity, between the sixth filtering cavity and the eighth filtering cavity, and between the sixth filtering cavity and the ninth filtering cavity, and the flying rod is arranged on the supporting clamping seat; one end of a flying rod arranged between the second filtering cavity and the fourth filtering cavity extends into the second filtering cavity, and the other end of the flying rod extends into the fourth filtering cavity; one end of a flying rod arranged between the second filtering cavity and the fifth filtering cavity extends into the second filtering cavity, and the other end of the flying rod extends into the fifth filtering cavity; one end of a flying rod arranged between the sixth filtering cavity and the eighth filtering cavity extends into the sixth filtering cavity, and the other end of the flying rod extends into the eighth filtering cavity; one end of a flying rod arranged between the sixth filtering cavity and the ninth filtering cavity extends into the sixth filtering cavity, and the other end of the flying rod extends into the ninth filtering cavity;

wherein, the flying bar is made of metal, and the flying bar is in the form of a sheet, and the flying bar is n-shaped.

Further, the filtering cavity is provided with a metal resonance rod and a tuning screw rod;

the metal resonance rod comprises a U-shaped side wall, a hollow inner cavity is formed in the U-shaped side wall, two ends of the U-shaped side wall bend and extend in a direction away from the hollow inner cavity so as to form disc-shaped structures at two ends of the U-shaped side wall, and one end of the tuning screw rod is arranged in the hollow inner cavity;

wherein, the filtering cavity is cylindrical, the diameter of the filtering cavity is less than 15mm, and the height of the filtering cavity is less than 17 mm.

Furthermore, the first filtering cavity, the third filtering cavity, the fifth filtering cavity, the seventh filtering cavity and the ninth filtering cavity of the filtering branch are in a row and are sequentially arranged along the second direction;

the second filtering cavity, the fourth filtering cavity, the sixth filtering cavity and the eighth filtering cavity of the filtering branch are in a row and are sequentially arranged along the second direction;

the first filter cavity and the third filter cavity of the filter branch are inductively and cross-coupled to form an inductive cross-coupling zero point at the high end of the pass band of the filter branch, and capacitive cross-coupling elements are respectively arranged between the third filter cavity and the fifth filter cavity of the filter branch and between the seventh filter cavity and the ninth filter cavity of the filter branch to form two capacitive cross-coupling zero points at the low end of the pass band of the filter branch; the pass band of the filter branch circuit ranges from 3450MHz to 3700 MHz.

Furthermore, a third filter cavity of the filter branch is respectively adjacent to the first filter cavity, the second filter cavity, the fourth filter cavity and the fifth filter cavity of the filter branch;

and the seventh filtering cavity of the filtering branch is respectively adjacent to the fifth filtering cavity, the sixth filtering cavity, the eighth filtering cavity and the ninth filtering cavity of the filtering branch.

Furthermore, the capacitive cross coupling element comprises a supporting clamping seat and a capacitive coupling probe, the supporting clamping seat is respectively arranged between the third filtering cavity and the fifth filtering cavity and between the seventh filtering cavity and the ninth filtering cavity, and the capacitive coupling probe is arranged on the supporting clamping seat; one end of a capacitive coupling probe arranged between the third filtering cavity and the fifth filtering cavity is welded with the cavity of the third filtering cavity, and the other end of the capacitive coupling probe is welded with the cavity of the fifth filtering cavity; one end of a capacitive coupling probe arranged between the seventh filtering cavity and the ninth filtering cavity is welded with the cavity of the seventh filtering cavity, and the other end of the capacitive coupling probe is welded with the cavity of the ninth filtering cavity;

the capacitive coupling probe comprises a metal sheet, and the material of the support clamping seat comprises PTFE or engineering plastics.

Furthermore, the second filter cavity and the ninth filter cavity are provided with a metal resonance rod and a first tuning screw rod;

the metal resonance rod comprises a U-shaped side wall, a first hollow inner cavity is formed in the U-shaped side wall, two ends of the U-shaped side wall bend and extend in the direction departing from the first hollow inner cavity so as to form a disc-shaped structure at two ends of the U-shaped side wall, the bottom of the U-shaped side wall is connected with a cavity of a filtering cavity where the U-shaped side wall is located, and one end of a first tuning screw rod is arranged in the first hollow inner cavity;

each of the first filtering cavity, the third filtering cavity and the eighth filtering cavity is provided with a medium resonance rod and a second tuning screw rod;

the medium resonance rod comprises a tubular side wall, and a second hollow inner cavity is formed in the tubular side wall;

one end of the second tuning screw is arranged in the second hollow inner cavity;

wherein, both ends of the tubular side wall are welded to the cavity of the filter cavity where the tubular side wall is located.

In order to solve the above technical problem, the present application further provides a communication device, which includes an antenna and a radio frequency unit connected to the antenna; the radio frequency unit comprises the filter and is used for filtering the radio frequency signal.

The application has at least the following beneficial effects: first, nine filter cavities of the filter branch are divided into two rows arranged along the first direction, so that the arrangement structure of the filter cavities is relatively regular, compared with irregular arrangement in the prior art, the arrangement mode is convenient for design and manufacture of the filter, the size of the filter can be reduced through the regular arrangement mode, and then, cross coupling zero points of the filter branches are formed through cross coupling of partial filter cavities, and the out-of-band rejection performance of the filter can be improved.

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 the structure of a filter of a first embodiment of the filter of the present application;

FIG. 2 is a schematic diagram of the topology of the filtering branches of the first embodiment of the filter of the present application;

figure 3 is a schematic diagram of the structure of the filter cavity of the first embodiment of the filter of the present application;

FIG. 4 is a schematic diagram of the structure of a capacitive cross-coupling element of a first embodiment of the filter of the present application;

FIG. 5 is a schematic diagram of the structure of the flying rod of the first embodiment of the filter of the present application;

FIG. 6 is a schematic diagram of the three-dimensional structure of a filter of a first embodiment of the filter of the present application;

FIG. 7 is a simulation of a filter according to a first embodiment of the filter of the present application;

fig. 8 is a schematic structural diagram of a filter of a second embodiment of the filter of the present application;

FIG. 9 is a schematic diagram of the topology of the filtering branches of a second embodiment of the filter of the present application;

fig. 10 is a schematic structural diagram of a third filter cavity and a fifth filter cavity of a filter branch of the second embodiment of the filter of the present application;

fig. 11 is a schematic structural diagram of a seventh filter cavity and a ninth filter cavity of a filter branch of the second embodiment of the filter of the present application;

FIG. 12 is an enlarged schematic view of a metal coupling probe and a support pedestal of a second embodiment of the filter of the present application;

figure 13 is a schematic diagram of the structure of the second filter cavity and the filter cavity of the ninth filter cavity of the second embodiment of the filter of the present application;

fig. 14 is a schematic structural view of filter cavities of the first to eighth filter cavities of the second embodiment of the filter of the present application;

FIG. 15 is a schematic diagram of the three-dimensional structure of a filter of a second embodiment of the filter of the present application;

FIG. 16 is a schematic diagram of a simulation of a filter of a second embodiment of the filter of the present application;

fig. 17 is a schematic diagram of an embodiment of a communication device of the present application.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be noted that the following examples are only illustrative of the present application, and do not limit the scope of the present application. Likewise, the following examples are only some examples and not all examples of the present application, and all other examples obtained by a person of ordinary skill in the art without any inventive step are within the scope of the present application.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Example one

Referring to fig. 1, fig. 1 is a schematic structural diagram of a filter according to a first embodiment of the present application.

As shown in fig. 1, the present embodiment provides a filter 20 including: a housing 210 and a filter branch 220. The housing 210 has a first direction W2 and a second direction L2 perpendicular to the first direction W2; the filtering branch 220 is disposed on the housing 210 and is composed of nine filtering cavities 200 coupled in sequence. Portions of the filter cavities 200 are cross-coupled to form cross-coupled zeros of the filter legs 220. Wherein the nine filter cavities 200 of the filter branch are divided into two columns arranged along the first direction W2.

As such, in the present embodiment, by dividing the nine filter cavities 200 of the filter branch 220 into two rows arranged along the first direction W2, the arrangement structure of the filter cavities 200 is relatively regular, which facilitates the design and manufacture of the filter 20 and reduces the volume of the filter 20 by the regular arrangement, compared to the irregular arrangement in the prior art.

The cross coupling zero point is also called a transmission zero point or a coupling zero point, so that zero point suppression can be realized, and the index debugging is facilitated. The cross-coupling zero point can make the transmission function of the filter 20 equal to zero, that is, the electromagnetic energy at the frequency point corresponding to the transmission zero point cannot pass through the network, so that the filter has a complete isolation effect, plays a role in inhibiting signals outside the pass band, and can better realize high isolation between the filter and a plurality of pass bands or the outside. Therefore, the cross-coupling zero point of the filtering branch 220 is formed, so that the indexes are convenient to debug, the cross-coupling zero point can play a role in inhibiting signals outside the passband, and the isolation degree between the signals inside the passband of the filter 20 and the signals outside the passband is improved.

The housing 210 may include a bottom wall, a side wall, and an upper wall to form a closed space. In the present embodiment, the casing 210 is merely illustrated for example, and the present invention is not limited thereto.

Specifically, the first filter cavity B1, the second filter cavity B2, the fifth filter cavity B5, the sixth filter cavity B6 and the ninth filter cavity B9 of the filter branch 220 are in a row and are sequentially arranged along the second direction L2; the third filter cavity B3, the fourth filter cavity B4, the seventh filter cavity B7 and the eighth filter cavity B8 of the filter branch 220 are in a row and are sequentially arranged along the second direction L2.

Referring to fig. 2, fig. 2 is a schematic diagram illustrating a topology of a filtering branch according to a first embodiment of the filter of the present application.

As shown in fig. 2, capacitive cross-coupling elements are respectively disposed between the second filter cavity B2 and the fourth filter cavity B4 of the filter branch 220, between the second filter cavity B2 and the fifth filter cavity B5 of the filter branch 220, between the sixth filter cavity B6 and the eighth filter cavity B8 of the filter branch 220, and between the sixth filter cavity B6 and the ninth filter cavity B9 of the filter branch 220, so as to form two capacitive cross-coupling zeros at the high end of the pass band of the filter branch and two capacitive cross-coupling zeros at the low end of the pass band; the pass band of the filtering branch circuit ranges from 2575MHz to 2615 MHz. The capacitive cross-coupling elements between the second filter cavity B2 and the fourth filter cavity B4 of the filter branch 220, between the second filter cavity B2 and the fifth filter cavity B5 of the filter branch 220, between the sixth filter cavity B6 and the eighth filter cavity B8 of the filter branch 220, and between the sixth filter cavity B6 and the ninth filter cavity B9 of the filter branch 220 are respectively equivalent to a capacitor C21, a capacitor C22, a capacitor C23, and a capacitor C24. Because the filter 20 is only provided with the capacitive cross coupling element, the material consistency of the filter 20 is good, and the complexity of the product is reduced. Thereby enabling to reduce the production cost.

The space utilization of the filter 20 may be improved by disposing one filter cavity 200 adjacent to a plurality of filter cavities 200, respectively, for example, the second filter cavity B2 of the filter branch 220 is disposed adjacent to the first filter cavity B1, the third filter cavity B3, the fourth filter cavity B4 and the fifth filter cavity B5 of the filter branch 220, respectively; the sixth filter cavity B6 of the filter branch 220 is respectively adjacent to the fifth filter cavity B5, the seventh filter cavity B7, the eighth filter cavity B8 and the ninth filter cavity B9 of the filter branch 220.

The space utilization of the filter 20 can be improved by reasonably setting the relative positions of the two columns of filter cavities 200, for example, the projection of the center of the third filter cavity B3 of the filter branch 220 in the second direction L2 is further located between the projection of the center of the first filter cavity B1 of the filter branch 220 in the second direction L2 and the projection of the center of the second filter cavity B2 of the filter branch 220 in the second direction L2; the projection of the center of the eighth filter cavity B8 of the filter branch 220 in the second direction L2 is further located between the projection of the center of the sixth filter cavity B6 of the filter branch 220 in the second direction L2 and the projection of the center of the ninth filter cavity B9 of the filter branch 220 in the second direction L2. In this way, the projection of the column of the third filter cavity B3 in the second direction L2 is located in the projection of the column of the ninth filter cavity B9 in the second direction L2, so that the space utilization rate of the filter 20 is improved, and the size of the filter 20 can be reduced.

Further, the space utilization rate of the filter 20 is further improved by specifically setting the arrangement form of the filter cavities 200, for example, the first filter cavity B1, the third filter cavity B3, the second filter cavity B2, the fourth filter cavity B4 and the fifth filter cavity B5 of the filter branch 220 may be sequentially arranged in an M shape; the fourth filtering cavity B4, the fifth filtering cavity B5, the seventh filtering cavity B7, the sixth filtering cavity B6 and the eighth filtering cavity B8 of the filtering branch 220 may be sequentially arranged in an M shape; the sixth filter chamber B6, the eighth filter chamber B8, and the ninth filter chamber B9 of the filter branch 220 may be arranged in sequence in a V-shape. Therefore, the filter cavities 200 are arranged regularly, and the filter cavities 200 in the row where the third filter cavity B3 is located and the filter cavities 200 in the row where the first filter cavity B1 is located are arranged in a staggered manner, so that the space utilization rate of the filter 20 is further improved.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a filter cavity of the first embodiment of the filter of the present application.

As shown in fig. 3, the filter chamber 200 is provided with a metal resonance rod 3B and a tuning screw 4B; the metal resonance rod 3B comprises a U-shaped side wall 31B, a hollow inner cavity 30B is formed in the U-shaped side wall 31B, two ends of the U-shaped side wall 31B bend and extend in a direction away from the hollow inner cavity 30B so as to form disc-shaped structures 32B at two ends of the U-shaped side wall 31B, and the bottom of the U-shaped side wall 31B is connected with the cavity of the filter cavity 200 where the U-shaped side wall 31B is located; one end of the tuning screw 4B is disposed within the hollow interior 30B. The bottom of the filter chamber 200 may be provided with a mounting post 5B, and the bottom of the U-shaped side wall 31B may be fixed to the mounting post 5B.

Based on the structure of the filter cavity 200, the power capacity of the filter 20 of the present application is larger than that of filters of other planar circuit structures.

The filter chamber 200 may be defined by the body 1B and the cover 2B. For example, the main body 1B is provided with an open groove, and the cover 2B is provided to cover the main body 1B, closing the open groove of the main body 1B, thereby forming the filter chamber 200. The cover 2B may be formed by an upper wall of the case 210, and the bottom wall 101B of the main body 1B may be formed by a bottom wall of the case 210. The cover body 2B can be provided with a screw hole, and the tuning screw rod 4B can penetrate through the screw hole.

Specifically, the metal resonant rod 3B may be made of invar steel, and the filter cavity may be a metal filter cavity. Wherein the filter cavity is also referred to as a resonant cavity and the metal filter cavity is thus also referred to as a metal resonant cavity. The filter cavity 200 of the present application may be cylindrical, and the diameter Φ of the filter cavity 200 is less than 15mm, and the height h of the filter cavity 200 is less than 17 mm.

Referring to fig. 4, fig. 4 is a schematic structural diagram of a capacitive cross-coupling element according to a first embodiment of the filter of the present application.

As shown in fig. 4, the capacitive cross-coupling element includes a support clamp 6B and a fly rod 7B. The supporting clamping seat 6B is respectively arranged between the second filter cavity B2 and the fourth filter cavity B4, between the second filter cavity B2 and the fifth filter cavity B5, between the sixth filter cavity B6 and the eighth filter cavity B8, and between the sixth filter cavity B6 and the ninth filter cavity B9. The flying bar 7B is disposed on the support holder 6B.

One end of a flying rod 7B arranged between the second filtering cavity B2 and the fourth filtering cavity B4 extends into the second filtering cavity B2, and the other end extends into the fourth filtering cavity B4; one end of a flying rod 7B arranged between the second filtering cavity B2 and the fourth filtering cavity B5 extends into the second filtering cavity B2, and the other end extends into the fifth filtering cavity B5; one end of a flying rod 7B arranged between the sixth filtering cavity B6 and the eighth filtering cavity B8 extends into the sixth filtering cavity B6, and the other end extends into the eighth filtering cavity B8; one end of the flying bar 7B arranged between the sixth filtering cavity B6 and the ninth filtering cavity B9 extends into the sixth filtering cavity B6, and the other end extends into the ninth filtering cavity B9. So that capacitive cross coupling is respectively realized between the second filter cavity B2 and the fourth filter cavity B4, between the second filter cavity B2 and the fifth filter cavity B5, between the sixth filter cavity B6 and the eighth filter cavity B8, and between the sixth filter cavity B6 and the ninth filter cavity B9.

In order to mass-produce the flying bar 7B by using the same stamping die and stamping equipment in a stamping manner, the production cost is reduced. The flying bar 7B may be made of metal, and the flying bar is in a sheet shape and n-shaped.

Further, refer to fig. 4 and 5 in combination, wherein fig. 5 is a schematic structural diagram of the flying bar of the first embodiment of the filter of the present application.

Specifically, the flying bar 7B has a third direction H2 and a fourth direction L3 that are perpendicular to each other, the third direction H2 being perpendicular to the first direction W2 and the second direction L2; the flying bar 7B includes a first coupling portion 71, a second coupling portion 73, and a connecting portion 72; the first and

second coupling parts

71 and 73 extend in the third direction H2, the connection part 72 extends in the fourth direction L3, and one end of the connection part 72 is connected to the first coupling part 71 and the other end of the connection part 72 is connected to the second coupling part 73.

Referring to fig. 4 and fig. 6 in combination, fig. 6 is a schematic three-dimensional structure diagram of a filter according to a first embodiment of the filter of the present application.

As shown in fig. 4-6, windows 300B may be respectively opened between the second filter cavity B2 and the fourth filter cavity B4, between the second filter cavity B2 and the fifth filter cavity B5, between the sixth filter cavity B6 and the eighth filter cavity B8, and between the sixth filter cavity B6 and the ninth filter cavity B9. The engaging groove 60 may be provided on the support cassette 6B such that the support cassette 6B is engaged with the window 300B through the engaging groove 60.

A window 300B may be formed between the first filter chamber B1 and the ninth filter chamber B9 coupled to the two filter chambers 200 in sequence. The first filter chamber B1 through the ninth filter chamber B9 may be coupled using windows. Thus, materials can be saved, and the production cost of the filter 20 can be reduced.

Of course, a metal coupling rib (not shown) may be disposed between at least some of the filter cavities 200 coupled in sequence, so that the coupling strength between at least some of the filter cavities 200 coupled in sequence is enhanced by the metal coupling rib.

The housing 210 is further provided with a first port (not shown) to which the first filter chamber B1 is connected and a second port (not shown) to which the ninth filter chamber B9 is connected. Wherein the first port and the second port may both be taps of the filter 20.

Referring to fig. 7, fig. 7 is a simulation diagram of a filter according to a first embodiment of the filter of the present application.

See the band curve 300 of the filter 20 shown in fig. 7. The point m1 and the point m2 are two points on the band curve 200. The frequency at point m1 is 2575.0MHz, and the rejection at point m1 is 4.31516 dB; the frequency at point m2 is 2615.0MHz and the rejection at point m2 is 3.92701 dB. Among them, the point m1 is also the lower cut-off frequency point, and the point m2 is also the upper cut-off frequency point. I.e. the passband of the filter 20 lies in the range 2575MHz-2615 MHz. The suppression at the lower-limit cutoff frequency point m1 and the upper-limit cutoff frequency point m2 is less than 5dB, that is, the suppression of the filter 20 is less than 5dB in the passband (2575MHz to 2615MHz), that is, the in-band loss of the filter 20 is small. The filter 20 generates two transmission zeros at the high end of the pass band and two transmission zeros at the low end of the pass band, so that the index of the filter 20 can be conveniently debugged, the filter can inhibit signals outside the pass band, and the isolation degree between the signals inside the pass band and the signals outside the pass band of the filter 20 is improved.

Such as return loss curve 400 of filter 20 shown in fig. 7. Where points m3 and m4 are two points on return loss curve 400. The frequency at point m3 was 2575MHz and the rejection at point m3 was 26.5492 dB. The frequency at point m4 is 2615MHz and the rejection at point m4 is 26.8199 dB. The filter 20 of the present application thus satisfies that, within the passband, the return loss of the transceiver port is greater than or equal to 16dB and the return loss of the antenna port is greater than or equal to 16 dB.

Specifically, indexes of parameters of the filter 20 corresponding to the simulation diagram shown in fig. 7 are as follows:

the maximum insertion loss is 5.2dB at normal temperature within the passband range of 2575MHz-2615 MHz;

in the passband range of 2575MHz-2615MHz, the maximum insertion loss is 6.2dB at the full temperature;

in the passband range of 2575MHz-2615MHz, the average insertion loss of any 20MHz bandwidth is less than or equal to 2.4dB at normal temperature;

in the passband range of 2575MHz-2615MHz, the average insertion loss of any 20MHz bandwidth is less than or equal to 2.5dB at full temperature;

in the passband range of 2575MHz-2615MHz, the passband ripple at full temperature is less than or equal to 4.0 dB;

within the frequency band range of 9KHz-2000MHz, the suppression is greater than or equal to 61 dB;

in the frequency band range of 2000MHz-2483.5MHz, the suppression is greater than or equal to 63 dB;

in the frequency band range of 2483.5MHz-2500MHz, the suppression is greater than or equal to 47 dB;

in the frequency band range of 2500MHz-2570MHz, the suppression is more than or equal to 42 dB;

in the frequency band range of 2620MHz-2690MHz, restrain greater than or equal to 30 dB;

in the range of 2690MHz-3200MHz, the inhibition is more than or equal to 57 dB;

within the range of 3200MHz-3400MHz, the inhibition is greater than or equal to 82 dB;

in the range of 3400MHz-3800MHz, the inhibition is greater than or equal to 58 dB;

suppression is greater than or equal to 21dB in the range of 3800MHz-5150 MHz;

in the range of 5150MHz-5270MHz, the suppression is greater than or equal to 46 dB;

in the range of 5270MHz-5350MHz, the suppression is greater than or equal to 42 dB;

in the range of 5350MHz-5850MHz, the suppression is greater than or equal to 42 dB;

suppression is greater than or equal to 20dB in the range of 5850MHz to 7900 MHz;

the suppression is greater than or equal to 10dB in the range of 7900MHz to 8000 MHz.

Therefore, the filter 20 of the present application satisfies the current use of 5G (5th Generation mobile networks, 5th Generation, also referred to as 5G technology or fifth Generation mobile communication technology), and relates to the frequency band of 2575MHz-2615 MHz.

Example two

Referring to fig. 8, fig. 8 is a schematic structural diagram of a filter according to a second embodiment of the filter of the present application.

As shown in fig. 8, the present embodiment provides a filter 10 including: a housing 110 and a filter branch 120. The housing 110 has a first direction W1 and a second direction 1L perpendicular to the first direction W1; and the filtering branch circuit 120 is arranged on the shell 110 and consists of nine filtering cavities A1-A9 which are coupled in sequence.

The housing 110 may include a bottom wall, a side wall, and an upper wall to form a closed space. In the present embodiment, the casing 110 is merely illustrated for example, and the present invention is not limited thereto.

Referring to fig. 9, fig. 9 is a schematic diagram illustrating a topology of a filtering branch according to a second embodiment of the filter of the present application.

As shown in fig. 9, the first filter cavity a1 and the third filter cavity A3 of the filter branch 120 are inductively cross-coupled to form an inductive cross-coupling zero of the filter branch 120, which is equivalent to the inductor L1 shown in fig. 9; capacitive cross-coupling elements are respectively arranged between the third filter cavity A3 and the fifth filter cavity a5 of the filter branch 120 and between the seventh filter cavity a7 and the ninth filter cavity a9 of the filter branch 120 to form two capacitive cross-coupling zeros of the filter branch 120, which are respectively equivalent to the capacitor C1 and the capacitor C2 shown in fig. 9, wherein the bandwidth range of the filter branch 120 is 3450MHz to 3700 MHz.

The coupling zero point is also called a transmission zero point, so that zero point suppression can be realized, and the debugging of indexes is facilitated. The transmission zero can make the transmission function of the filter 10 equal to zero, that is, the electromagnetic energy at the frequency point corresponding to the transmission zero can not pass through the network, thus playing a role of complete isolation, playing a role of inhibiting signals outside the pass band, and better realizing high isolation between the pass band and the outside. Therefore, an inductive cross-coupling zero is generated at the high end of the pass band by the inductive cross-coupling between the first filter cavity a1 and the third filter cavity A3 of the filter branch 120, and two capacitive cross-coupling zeros are generated at the low end of the pass band by the capacitive cross-coupling between the third filter cavity A3 of the filter branch 120 and the fifth filter cavity a5 of the filter branch 120, and the capacitive cross-coupling between the seventh filter cavity a7 of the filter branch 120 and the ninth filter cavity a9 of the filter branch 120. Therefore, coupling zero points are respectively generated at the high end and the low end of the pass band, so that the debugging index is convenient, the signals outside the pass band can be inhibited, and the isolation degree between the signals inside the pass band and the signals outside the pass band of the filter 10 is improved.

Referring to fig. 8, in particular, the nine filter cavities a1-a9 of the filter branch 120 are divided into two columns arranged along the first direction W1; the first filtering cavity a1, the third filtering cavity A3, the fifth filtering cavity a5, the seventh filtering cavity a7 and the ninth filtering cavity a9 of the filtering branch 120 are in a row and are sequentially arranged along the second direction 1L; the second filter cavity a2, the fourth filter cavity a4, the sixth filter cavity a6 and the eighth filter cavity A8 of the filter branch 120 are in a row and are sequentially arranged along the second direction 1L.

By dividing the nine filter cavities a1-a9 of the filter branch 120 into two rows arranged along the first direction W1, the arrangement structure of the filter cavities is relatively regular, which facilitates the design and manufacture of the filter 10 and reduces the volume of the filter 10 by the regular arrangement, compared to the irregular arrangement in the prior art.

The space utilization of the filter 10 may be improved by disposing one filter cavity adjacent to a plurality of filter cavities, respectively, for example, the third filter cavity A3 of the filter branch 120 is disposed adjacent to the first filter cavity a1, the second filter cavity a2, the fourth filter cavity a4 and the fifth filter cavity a5 of the filter branch 120, respectively; the seventh filtering cavity a7 of the filtering branch 120 is respectively adjacent to the fifth filtering cavity a5, the sixth filtering cavity a6, the eighth filtering cavity A8 and the ninth filtering cavity a9 of the filtering branch 120.

The space utilization of the filter 10 can be improved by reasonably setting the relative positions of the two rows of filter cavities, for example, the projection of the center of the second filter cavity a2 of the filter branch 120 in the second direction 1L is further located between the projection of the center of the first filter cavity a1 of the filter branch 120 in the second direction 1L and the projection of the center of the third filter cavity A3 of the filter branch 120 in the second direction 1L; the projection of the center of the eighth filter cavity A8 of the filter branch 120 in the second direction 1L is further located between the projection of the center of the seventh filter cavity a7 of the filter branch 120 in the second direction 1L and the projection of the center of the ninth filter cavity a9 of the filter branch 120 in the second direction 1L. In this way, the projection of the row of the second filter cavity a2 in the second direction 1L is located in the projection of the row of the first filter cavity a1 in the second direction 1L, so that the space utilization rate of the filter 10 is improved, and the size of the filter 10 can be reduced.

Further, the space utilization of the filter 10 is further improved by specifically setting the arrangement form of the filter cavities, for example, the first filter cavity a1 to the fifth filter cavity a5 of the filter branch 120 may be arranged in an M shape; the fifth filtering cavity a5 of the filtering branch 120 to the ninth filtering cavity a9 of the filtering branch 120 may be arranged in an M shape; the fourth filter chamber a4 through the sixth filter chamber a6 of the filter arm 120 may be arranged in a V-shape. Therefore, the filter cavities are arranged regularly, and the filter cavities in a row where the second filter cavity A2 is located and the filter cavities in a row where the first filter cavity A1 is located are arranged in a staggered mode, so that the space utilization rate of the filter 10 is further improved.

Referring to fig. 10 and fig. 11, fig. 10 is a schematic structural diagram of a third filter cavity and a fifth filter cavity of a filter branch of a second embodiment of the filter of the present application; fig. 11 is a schematic structural diagram of a seventh filter cavity and a ninth filter cavity of a filter branch of the second embodiment of the filter of the present application.

As shown in fig. 10 and 11, further, the capacitive cross coupling element includes a supporting clamp 130A and a capacitive coupling probe 140A, the supporting clamp 130A is respectively disposed between the third filter cavity A3 and the fifth filter cavity a5, and between the seventh filter cavity a7 and the ninth filter cavity a9, and the capacitive coupling probe 140A is disposed on the supporting clamp 130A.

As shown in fig. 10, one end of the capacitive coupling probe 140A disposed between the third filter chamber A3 and the fifth filter chamber a5 is welded to the chamber body of the third filter chamber A3, and the other end is welded to the chamber body of the fifth filter chamber a 5; as shown in fig. 11, one end of the capacitive coupling probe 140A disposed between the seventh filter chamber a7 and the ninth filter chamber a9 is welded to the chamber of the seventh filter chamber a7, and the other end is welded to the chamber of the ninth filter chamber a 9.

Referring to fig. 10 and 11 in combination, in particular, the capacitive coupling probe 140A includes a metal sheet, and the material of the support clamp 130A includes PTFE or engineering plastic. Windows may be respectively opened between the third filter chamber A3 and the fifth filter chamber a5, and between the seventh filter chamber a7 and the ninth filter chamber a9, and the support clamping seat 130A may be disposed at the windows. The support socket 130A may have a second direction 1L and a third direction H1 perpendicular to each other, wherein the third direction H1 is also perpendicular to the first direction W1.

Specifically, the cavity of each filter cavity may include a main body 100A and a cover 200A. The main body 100A is provided with an open slot, the cover body 200A covers the main body 100A, and the open slot of the main body 100A is closed to form a filtering cavity. The cover 200A may be formed of an upper wall of the case 110, and the bottom wall 101A of the main body 100A may be formed of a bottom wall of the case 110.

Referring to fig. 12, fig. 12 is an enlarged schematic view of a metal coupling probe and a supporting card seat of a second embodiment of the filter of the present application.

As shown in fig. 12, the metal coupling probe 140A includes a first coupling portion 141, a connection portion 142, and a second coupling portion 143. One end of the first coupling part 141 may be connected to one end of the connection part 142, and the other end of the connection part 142 may be connected to one end of the second coupling part 143.

Referring to fig. 10 and 12, in the metal coupling probe 140A disposed between the third filter cavity A3 and the fifth filter cavity a5, the first coupling portion 141 extends into the third filter cavity A3 and couples with the third filter cavity A3, the second coupling portion 143 extends into the fifth filter cavity a5 and couples with the fifth filter cavity a5, an end of the first coupling portion 141 away from the connecting portion 142 is welded to a cavity of the third filter cavity A3, and an end of the second coupling portion 143 away from the connecting portion 142 is welded to a cavity of the fifth filter cavity a 5. This enables a double-ended short circuit of the metal coupling probe 140A disposed between the third filter chamber A3 and the fifth filter chamber a 5.

To better secure the metal coupling probe 140A disposed between the third filter chamber A3 and the fifth filter chamber a5, the support clamp 130A disposed between the third filter chamber A3 and the fifth filter chamber a5 may include a first portion extending into the third filter chamber A3 along the second direction 1L and a second portion extending into the fifth filter chamber a5 along the second direction 1L. The metal coupling probe 140A may be disposed in the supporting socket 130A, and the first coupling portion 141 is located at the first portion, and the second coupling portion 143 is located at the second portion. An end of the first coupling part 141 away from the connecting part 142 may protrude from an end of the support socket 130A in the third direction H1, so that the end of the first coupling part 141 away from the connecting part 142 is welded with the cavity of the third filter cavity A3; an end of the second coupling part 143 away from the connection part 142 may protrude from the other end of the support socket 130A in the third direction H1, so that the end of the second coupling part 143 away from the connection part 142 is welded with the cavity of the fifth filter cavity a 5.

Specifically, an end of the first coupling part 141 remote from the connection part 142 may be welded to one of the bottom wall 101A of the third filter chamber A3 and the cover body 200A, and an end of the second coupling part 143 remote from the connection part 142 may be welded to the other of the bottom wall 101A of the fifth filter chamber a5 and the cover body 200A.

Referring to fig. 11 and 12, in the metal coupling probe 140A disposed between the seventh filter cavity a7 and the ninth filter cavity a9, the first coupling portion 141 extends into the seventh filter cavity a7 and is coupled to the seventh filter cavity a7, the second coupling portion 143 extends into the ninth filter cavity a9 and is coupled to the ninth filter cavity a9, an end of the first coupling portion 141 away from the connecting portion 142 is welded to a cavity of the seventh filter cavity a7, and an end of the second coupling portion 143 away from the connecting portion 142 is welded to a cavity of the ninth filter cavity a 9. This enables a double-ended short circuit of the metal coupling probe 140A disposed between the seventh filter cavity a7 and the ninth filter cavity a 9.

To better secure the metal coupling probe 140A disposed between the seventh filter cavity a7 and the ninth filter cavity a9, the support clamp 130A disposed between the seventh filter cavity a7 and the ninth filter cavity a9 may include a first portion extending into the seventh filter cavity a7 along the second direction 1L and a second portion extending into the fifth filter cavity a5 along the second direction 1L. The metal coupling probe 140A may be disposed in the supporting socket 130A, and the first coupling portion 141 is located at the first portion, and the second coupling portion 143 is located at the second portion. An end of the first coupling part 141 away from the connecting part 142 may protrude from an end of the support socket 130A in the third direction H1, so that the end of the first coupling part 141 away from the connecting part 142 is welded with the cavity of the seventh filter cavity a 7; an end of the second coupling part 143 away from the connection part 142 may protrude from the other end of the support cassette 130A in the third direction H1, so that the end of the second coupling part 143 away from the connection part 142 is welded with the cavity of the ninth filter cavity a 9.

Specifically, an end of the first coupling part 141 remote from the connection part 142 may be welded to one of the bottom wall 101A of the seventh filter chamber a7 and the cover body 200A, and an end of the second coupling part 143 remote from the connection part 142 may be welded to the other of the bottom wall 101A of the ninth filter chamber a9 and the cover body 200A.

Referring to fig. 13, fig. 13 is a schematic structural diagram of the second filter cavity and the filter cavity of the ninth filter cavity of the second embodiment of the filter of the present application.

The second filter cavity a2 and the ninth filter cavity a9 are provided with a first mounting post 150A, a metal resonance rod 160A and a first tuning screw 170A; the metal resonance rod 160A includes a U-shaped side wall 161A, the U-shaped side wall 161A is formed with a first hollow cavity 162A, two ends of the U-shaped side wall 161A are bent and extended in a direction away from the first hollow cavity 162A to form a disc-shaped structure 163A at two ends of the U-shaped side wall 161A, and the disc-shaped structure 163A may be parallel to the bottom of the U-shaped side wall 161A; one end of the first tuning screw 170A is disposed within the first hollow interior 162A; wherein the U-shaped sidewall 161A may be fixed to the first mounting post 150A.

First mounting post 150A may be disposed on bottom wall 101A of second filter chamber A2 and bottom wall 101A of ninth filter chamber A9. The cover 200A of the second filter cavity a2 and the cover 200A of the ninth filter cavity a9 may have a first screw hole, and the first tuning screw 170A may be disposed through the first screw hole.

Specifically, the first tuning screw 170A may be a metal tuning screw. The metal resonant rod 160A may be made of invar steel.

Referring further to fig. 14, fig. 14 is a schematic structural diagram of filter cavities from the first filter cavity, the third filter cavity to the eighth filter cavity of the second embodiment of the filter of the present application.

As shown in fig. 14, each of the first filter chamber a1, the third filter chamber A3 through the eighth filter chamber A8 is provided with a dielectric resonance rod 180A and a second tuning screw 190A; the dielectric resonance rod 180A may be a TM mode resonance rod. The dielectric resonator rod 180A may include a tubular sidewall 181A, the tubular sidewall 181A being formed with a second hollow inner cavity 182A; one end of the second tuning screw 190A is disposed within the second hollow interior cavity 182A; wherein, both ends of the tubular side wall 181A are welded to the cavity of the filter cavity where the tubular side wall 181A is located. Specifically, the tubular sidewall 181A may be disposed along the third direction H1, one end of the tubular sidewall 181A is welded to the bottom wall 101A of the cavity in which the tubular sidewall 181A is located, and the other end of the tubular sidewall 181A is welded to the cover 200A of the cavity in which the tubular sidewall 181A is located. The double-end short circuit of the dielectric resonance rod 180A can be achieved by welding both ends of the tubular side wall 181A to the cavity of the filter cavity where the tubular side wall 181A is located.

With reference to fig. 14 and fig. 13, in this embodiment, by reasonably setting the structure of the nine filter cavities a1-a9, the resonant rods inside the second filter cavity a2 and the ninth filter cavity a9 are the metal resonant rod 160A, and the resonant rods inside the first filter cavity a1, the third filter cavity A3 to the eighth filter cavity A8 are the dielectric resonant rod 180A. Since the insertion loss of the dielectric resonance rod 180A is small, the power consumption of the filter 10 can be reduced, and the first filter cavity a1, the third filter cavity A3 to the eighth filter cavity A8 can bear a larger resonance frequency. Secondly, the dielectric resonance rod 180A enables electromagnetic wave energy to be concentrated mainly around the dielectric resonance rod 180A, and the design size of the filter cavity can be reduced, thereby enabling the size of the filter 10 to be reduced.

Referring to fig. 15, fig. 15 is a schematic three-dimensional structure diagram of a filter according to a second embodiment of the filter of the present application.

As shown in fig. 15, a window 300A is formed between two filter cavities coupled in sequence from the first filter cavity a1 to the ninth filter cavity a 9. The first filter chamber a1 through the ninth filter chamber a9 may be coupled using a pure window. Thus, materials can be saved, and the production cost of the filter 10 can be reduced. The frequency-adjusting screw 400A may be provided at the window 300A between two filter chambers coupled in sequence among the first filter chamber a1 through the ninth filter chamber a 9.

Metal coupling ribs (not shown) may be disposed between two filter cavities coupled in sequence from the first filter cavity a1 to the ninth filter cavity a 9. Thus, the coupling strength of the two filter cavities coupled in sequence is enhanced by the metal coupling rib.

A window 300A may be formed between the first filter cavity a1 and the third filter cavity A3, and a metal coupling rib is disposed in the window 300A, so that the first filter cavity a1 and the third filter cavity A3 realize inductive cross coupling. A fm screw 400A may be disposed in the window 300A between the first filter chamber a1 and the third filter chamber A3.

Referring to fig. 16, fig. 16 is a simulation diagram of a filter according to a second embodiment of the filter of the present application.

See the band curve 500 of the filter branch 120 as shown in fig. 16. The point m1, the point m2, the point m3, the point m4, and the point m5 are points on the band curve 500. Here, the point m1 is a lower-limit cutoff frequency point, and the point m2 is an upper-limit cutoff frequency point. The frequency of the lower-limit cutoff frequency point m1 is 3450MHz, the frequency of the upper-limit cutoff frequency point m2 is 3700MHz, that is, the simulated bandwidth of the filter branch circuit 120 is in the range of 3450MHz to 3700 MHz. The filter 10 provided by the present application can be applied to 5G communication devices.

Wherein, the average insertion loss of the filtering branch 120 is less than 1.2dB in the bandwidth range. Wherein, the suppression (suppression, i.e. insertion loss, sometimes also referred to as loss) at the lower limit cut-off frequency point m1 is 1.926dB, and the suppression at the upper limit cut-off frequency point m2 is 1.359dB, that is, within the bandwidth range, the suppression of the filter branch 120 is less than 2.0dB, that is, the in-band loss of the filter branch 120 is small.

As shown in fig. 16, a point m3, a point m4, and a point m5 are transmission zeros. The frequency of the transmission zero point m3 is in the range of 3428 MHz-3432 MHz, and the suppression at the transmission zero point m3 is 56.525 dB. The frequency of the transmission zero point m4 is in the range of 3718 MHz-3722 MHz, and the suppression at the transmission zero point m4 is 43.651 dB. The frequency of the transmission zero point m5 is 3395 MHz-3405 MHz, and the suppression at the transmission zero point m5 is more than 70 dB. The filter 10 of the present application is therefore able to achieve good out-of-band rejection performance.

The present application further provides a communication device, as shown in fig. 17, fig. 17 is a schematic diagram of an embodiment of the communication device of the present application.

As shown in fig. 17, the communication device 30 of this embodiment includes an antenna 32 and a Radio frequency unit 31, where the antenna 32 is connected to the Radio frequency unit 31, and the Radio frequency unit 31 may be an rru (remote Radio unit). The rf unit 31 includes the filter 10 or the filter 20 disclosed in the above embodiments, and is used for filtering the rf signal.

In other embodiments, the rf unit 31 may be integrated with the Antenna 32 to form an active Antenna unit (aau).

The above embodiments are merely examples and are not intended to limit the scope of the present disclosure, and all modifications, equivalents, and flow charts using the contents of the specification and drawings of the present disclosure or those directly or indirectly applied to other related technical fields are intended to be included in the scope of the present disclosure.

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 filtering branch is arranged on the shell and consists of nine filtering cavities which are sequentially coupled, and part of the filtering cavities are in cross coupling to form a cross coupling zero point of the filtering branch;

and nine filter cavities of the filter branch circuit are divided into two rows arranged along the first direction.

2. The filter of claim 1,

the first filtering cavity, the second filtering cavity, the fifth filtering cavity, the sixth filtering cavity and the ninth filtering cavity of the filtering branch are in a row and are sequentially arranged along the second direction;

capacitive cross-coupling elements are respectively arranged between the second filter cavity and the fourth filter cavity of the filter branch, between the second filter cavity and the fifth filter cavity of the filter branch, between the sixth filter cavity and the eighth filter cavity of the filter branch, and between the sixth filter cavity and the ninth filter cavity of the filter branch, so as to form two capacitive cross-coupling zeros at the high end of the pass band and two capacitive cross-coupling zeros at the low end of the pass band of the filter branch; the pass band range of the filtering branch is 2575MHz-2615 MHz.

3. The filter of claim 2,

the second filtering cavity of the filtering branch is respectively adjacent to the first filtering cavity, the third filtering cavity, the fourth filtering cavity and the fifth filtering cavity of the filtering branch;

4. The filter of claim 3,

the capacitive cross coupling element comprises a supporting clamping seat and a flying rod, the supporting clamping seat is respectively arranged between the second filtering cavity and the fourth filtering cavity, between the second filtering cavity and the fifth filtering cavity, between the sixth filtering cavity and the eighth filtering cavity, and between the sixth filtering cavity and the ninth filtering cavity, and the flying rod is arranged on the supporting clamping seat; one end of the flying rod arranged between the second filtering cavity and the fourth filtering cavity extends into the second filtering cavity, and the other end of the flying rod extends into the fourth filtering cavity; one end of the flying rod arranged between the second filtering cavity and the fifth filtering cavity extends into the second filtering cavity, and the other end of the flying rod extends into the fifth filtering cavity; one end of the flying rod arranged between the sixth filtering cavity and the eighth filtering cavity extends into the sixth filtering cavity, and the other end of the flying rod extends into the eighth filtering cavity; one end of the flying rod arranged between the sixth filtering cavity and the ninth filtering cavity extends into the sixth filtering cavity, and the other end of the flying rod extends into the ninth filtering cavity;

the flying bar is made of metal, is in a sheet shape and is in an n shape.

5. The filter of claim 4,

the filtering cavity is provided with a metal resonance rod and a tuning screw rod;

wherein, the filtering cavity is cylindrical, just the diameter of filtering cavity is less than 15mm, the height of filtering cavity is less than 17 mm.

6. The filter of claim 1,

the first filtering cavity, the third filtering cavity, the fifth filtering cavity, the seventh filtering cavity and the ninth filtering cavity of the filtering branch are in a row and are sequentially arranged along the second direction;

the first filter cavity and the third filter cavity of the filter branch are inductively cross-coupled to form an inductive cross-coupling zero point at the high end of the pass band of the filter branch, and capacitive cross-coupling elements are respectively arranged between the third filter cavity and the fifth filter cavity of the filter branch and between the seventh filter cavity and the ninth filter cavity of the filter branch to form two capacitive cross-coupling zero points at the low end of the pass band of the filter branch; the pass band range of the filtering branch circuit is 3450 MHz-3700 MHz.

7. The filter of claim 6,

the third filtering cavity of the filtering branch is respectively adjacent to the first filtering cavity, the second filtering cavity, the fourth filtering cavity and the fifth filtering cavity of the filtering branch;

8. The filter of claim 7,

the capacitive cross coupling element comprises a supporting clamping seat and a capacitive coupling probe, the supporting clamping seat is respectively arranged between the third filtering cavity and the fifth filtering cavity and between the seventh filtering cavity and the ninth filtering cavity, and the capacitive coupling probe is arranged on the supporting clamping seat; one end of the capacitive coupling probe arranged between the third filtering cavity and the fifth filtering cavity is welded with the cavity of the third filtering cavity, and the other end of the capacitive coupling probe is welded with the cavity of the fifth filtering cavity; one end of the capacitive coupling probe arranged between the seventh filtering cavity and the ninth filtering cavity is welded with the cavity of the seventh filtering cavity, and the other end of the capacitive coupling probe is welded with the cavity of the ninth filtering cavity;

9. The filter of claim 8,

the second filtering cavity and the ninth filtering cavity are provided with a metal resonance rod and a first tuning screw rod;

the metal resonance rod comprises a U-shaped side wall, a first hollow inner cavity is formed in the U-shaped side wall, two ends of the U-shaped side wall bend and extend in a direction departing from the first hollow inner cavity so as to form disc-shaped structures at two ends of the U-shaped side wall, the bottom of the U-shaped side wall is connected with a cavity of the filtering cavity where the U-shaped side wall is located, and one end of the first tuning screw rod is arranged in the first hollow inner cavity;

the dielectric resonance rod comprises a tubular side wall, and a second hollow inner cavity is formed in the tubular side wall;

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