CN114300822A - Cavity filter - Google Patents
Cavity filter Download PDFInfo
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- CN114300822A CN114300822A CN202111683360.2A CN202111683360A CN114300822A CN 114300822 A CN114300822 A CN 114300822A CN 202111683360 A CN202111683360 A CN 202111683360A CN 114300822 A CN114300822 A CN 114300822A
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- 239000000523 sample Substances 0.000 claims abstract description 19
- 238000013461 design Methods 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract description 4
- 230000008569 process Effects 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 description 9
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Abstract
The invention relates to the field of filters, and particularly discloses a cavity filter which comprises a box body, a fine adjustment assembly and two feed heads; the two feed heads are arranged on one side of the box body, and a coupling probe is arranged in each feed head; at least two filtering cavities are arranged in the box body, a partition plate is arranged between every two adjacent filtering cavities, and the two coupling probes penetrate through the box body and are arranged in the two adjacent filtering cavities; a resonator is arranged in each filtering cavity, a tuning screw is arranged in each resonator, and two ends of each tuning screw are connected with the box body; the baffle is provided with a coupling window, and the fine adjustment assembly is arranged in the coupling window. According to the cavity filter, through the structural design of the cavity filter, the size of the cavity filter is smaller under the same performance, the cavity filter is easy to process and convenient to integrate and install, and the passband range and the basic performance of the cavity filter can be adjusted through the fine adjustment component.
Description
Technical Field
The invention relates to the field of filters, in particular to a cavity filter.
Background
The filter filters electromagnetic wave signals, allows required signals to pass through and suppresses unnecessary signals, and mainly aims to solve the problem of interference between wireless communication systems with different frequency bands and different forms. The cavity filter is one of microwave filters, and its cavity is generally made up by integrally cutting metal, so that it is firm in structure, and possesses good frequency-selecting filtering action in circuit and electronic high-frequency system, and can inhibit out-of-band useless signal and noise. The base station needs a high-power and high-stability filter product, and is one of the largest application markets of the filters. With the rapid development of modern communication technology, communication frequency resources are more and more tense, microwave frequency bands are relatively crowded and intervals are more and more dense, which has higher requirements on the performance of microwave filters used for base stations, low-pass band insertion loss, high-impedance band rejection, high-power capacity, broadband application and the like become main technical indexes, and the miniaturization of volume, the reduction of cost and the shortening of design cycle by a rapid design method also become key technical requirements.
The modern cavity filter design generally adopts a network synthesis method, one important link of the synthesis method is to select a proper approximation function, and Chebyshev is called as an optimal approximation function; however, the transmission zero of the filter designed by the approximation function is at infinity, the suppression effect at the edge of the passband is poor, and the filter order needs to be increased to increase the out-of-band suppression, so that the size of the filter is increased definitely, which is contrary to the development trend of high performance and miniaturization of the filter; therefore, it is necessary to introduce a transmission zero near the passband range, which can improve the out-of-band rejection characteristics of the cavity filter.
The existing cavity filter usually increases out-of-band rejection by increasing the number of cavities, and satisfies the effect of passband edge rejection, so that the filter is inconvenient to effect and adjust all the time, and the out-of-band rejection is poor, so that the cavity filter is large in size, complex in structure, difficult to process and adjust, and not beneficial to industrial production.
Disclosure of Invention
The invention provides a cavity filter, aiming at solving the problems of large volume, complex structure, difficult processing and adjustment and difficult industrial production of the existing cavity filter.
The technical scheme adopted by the invention is a cavity filter, which comprises: the feed device comprises a box body, a fine adjustment assembly and two feed heads;
the two feed heads are arranged on one side of the box body, and a coupling probe is arranged in each feed head;
at least two filtering cavities are arranged in the box body, a partition plate is arranged between every two adjacent filtering cavities, and the two coupling probes penetrate through the box body and are arranged in the two adjacent filtering cavities;
a resonator is arranged in each filtering cavity, a tuning screw is arranged in each resonator, the tuning screw penetrates through the resonators, and two ends of each tuning screw are connected with the box body;
the diaphragm is provided with a coupling window, the fine tuning assembly is arranged in the coupling window, and the fine tuning assembly is used for adjusting the passband range and the basic performance of the cavity filter.
Preferably, the fine tuning assembly comprises a transverse tuning rod, the transverse tuning rod penetrates through the coupling window, and the middle part of the transverse tuning rod is fixedly connected with the partition plate.
Preferably, when the number of the filter cavities is more than two, two of the filter cavities are arranged in the box body in a group along the transverse direction, and a plurality of groups of two filter cavities are arranged in the longitudinal direction.
Preferably, the coupling window is arranged on the partition plate between the adjacent filter cavities, and only one coupling window is arranged between the adjacent filter cavities.
Preferably, when the coupling window is provided in plurality, the lateral tuning rod is provided only in the coupling window between two of the coupling probes.
Preferably, the fine adjustment assembly further comprises a window section adjusting rod, the window section adjusting rod is arranged in the middle of the coupling window which is not provided with the transverse tuning rod, the window section adjusting rod is parallel to the adjacent partition plate, and one end of the window section adjusting rod is movably connected with the box body.
The invention also discloses a fourth-order cavity filter, which comprises: the feed device comprises a box body, a fine adjustment assembly and two feed heads;
the two feed heads are arranged at the front end of the box body, and a coupling probe is arranged in each feed head;
the box body is internally provided with four filtering cavities, namely a first filtering cavity and a fourth filtering cavity which are positioned at the front end of the box body, a second filtering cavity and a third filtering cavity which are positioned on the rear side surface of the box body, and a partition plate is arranged between every two adjacent filtering cavities;
the two coupling probes respectively penetrate through the box body and are respectively introduced into the first filtering cavity and the fourth filtering cavity;
resonators are arranged in the four filter cavities, tuning screws are arranged in the resonators, the tuning screws penetrate through the resonators, and two ends of each tuning screw are connected with the box body;
each partition plate is provided with a coupling window, and the coupling window is used for communicating two filtering cavities adjacent to the partition plate;
the fine tuning component is arranged in the coupling window and used for adjusting the passband range and the basic performance of the cavity filter.
Preferably, the fine tuning assembly comprises a transverse tuning rod, the transverse tuning rod is arranged between the first filtering cavity and the fourth filtering cavity, and the middle part of the transverse tuning rod is fixedly connected with the partition plate.
Preferably, the fine adjustment assembly further comprises three window section adjusting rods, the window section adjusting rods are arranged in the coupling windows without the transverse tuning rods, the window section adjusting rods are parallel to the partition plates, and one ends of the window section adjusting rods are movably connected with the box body.
The invention has the beneficial effects that:
the coupling window is arranged on the partition plate, the fine tuning assembly is arranged in the coupling window and used for adjusting the passband range and the basic performance of the cavity filter, so that the filter is smaller in size under the same performance, easy to process and convenient to integrate and install.
Preferably, the fine tuning assembly comprises a transverse tuning rod, the transverse tuning rod penetrates through the coupling window, the middle part of the transverse tuning rod is fixedly connected with the partition plate, and when a plurality of coupling windows are arranged, the transverse tuning rod is only arranged in the coupling window between the two coupling probes; the transmission zero point is arranged near the passband of the filter, the out-of-band rejection characteristic of the filter is improved, and the channel selectivity of the cavity filter is improved while the order and the volume of the filter are not improved.
Drawings
The invention will be further described with reference to the accompanying drawings, in which:
FIG. 1 is an external schematic view of a cavity filter according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of the interior of a cavity filter according to one embodiment of the present invention;
FIG. 3 is a top view of the interior of a cavity filter according to one embodiment of the invention;
FIG. 4 is an equivalent circuit diagram of a cavity filter without a transverse tuning rod according to another embodiment of the present invention;
fig. 5 is an equivalent circuit diagram of a cavity filter with a transverse tuning rod added according to another embodiment of the present invention;
FIG. 6 is a graph of the effect of the height of the tuning rod on the filter insertion loss according to another embodiment of the present invention;
FIG. 7 is a graph of the effect of the diameter of the tuning rod on the filter insertion loss according to another embodiment of the present invention;
FIG. 8 is a graph of the effect of the length of the tuning rod on the cavity filter insertion loss according to another embodiment of the present invention;
fig. 9 is a graph of the insertion loss of a cavity filter without the addition of a lateral tuning rod according to another embodiment of the present invention;
fig. 10 is a graph of the insertion loss of a cavity filter with the addition of a transverse tuning rod according to another embodiment of the present invention.
In the figure: 1. a transverse tuning rod; 2. a resonator; 3. a partition plate; 4. an upper cover; 5. a base; 6. a feed head; 7. a coupling probe; 8. a window section adjusting rod; 9. a tuning screw; 501. a first filter cavity; 502. a second filter cavity; 503. a third filter cavity; 504. and a fourth filter cavity.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
One embodiment of the present invention generally provides a filter for a frequency range of 800MHz-1500 MHz. In the embodiment, the transverse tuning rod 1 is added between the inner adjacent cavities, and the cavity filter is provided with a transmission zero near a pass band according to the size of the cavity filter and the length, position and diameter of the transverse tuning rod 1, so that the order and volume of the filter are not required to be increased to improve the channel selectivity, and when the signals in the pass band of the filter are ensured to be smooth and not pass through, the frequency signals outside the pass band are steeply reduced in the stop band, and the out-of-band rejection level of the cavity filter is improved.
The cavity filter disclosed in this embodiment includes: the device comprises a box body, a fine adjustment component and two feed heads 6;
the two feed heads 6 are arranged on one side of the box body, and a coupling probe 7 is arranged in each feed head 6;
at least two filtering cavities are arranged in the box body, a partition plate 3 is arranged between every two adjacent filtering cavities, and the two coupling probes 7 penetrate through the box body and are arranged in the two adjacent filtering cavities respectively;
a resonator 2 is arranged in each filter cavity, a tuning screw 9 is arranged in each resonator 2, the tuning screw 9 penetrates through the resonators 2, and two ends of each tuning screw 9 are connected with the box body;
and a coupling window is arranged on the partition plate 3, the fine tuning assembly is arranged in the coupling window, and the fine tuning assembly is used for adjusting the pass band range and the basic performance of the cavity filter.
Preferably, the fine tuning assembly comprises a transverse tuning rod 1, the transverse tuning rod 1 penetrates through the coupling window, and the middle part of the transverse tuning rod 1 is fixedly connected with the partition plate 3.
Preferably, when the number of the filter cavities is more than two, two of the filter cavities are arranged in the box body in a group along the transverse direction, and a plurality of groups of two filter cavities are arranged in the longitudinal direction.
Preferably, the coupling window is arranged on the partition plate 3 between the adjacent filter cavities, and only one coupling window is arranged between the adjacent filter cavities.
Preferably, when the coupling window is provided in plurality, the lateral tuning rod 1 is provided only in the coupling window between two of the coupling probes 7.
Preferably, the fine adjustment assembly further comprises a window section adjusting rod 8, the window section adjusting rod 8 is arranged in the middle of the coupling window which is not provided with the transverse tuning rod 1, the window section adjusting rod 8 is parallel to the adjacent partition plate 3, and one end of the window section adjusting rod 8 is movably connected with the box body.
Referring to fig. 1 to 3, as another embodiment of the present invention, this embodiment specifically discloses a fourth-order cavity filter, and the passband frequency range is 800MHZ to 1.5 GHz; the size range of the cavity filter of the embodiment is as follows: the length is 80mm-150mm, the width is 80mm-150mm, and the height is 30mm-50 mm; electromagnetic wave signals enter the cavity filter from one feed head 6, form stable field distribution in the cavity filter, and enter other equipment through the other feed head 6 of the cavity filter.
A fourth order cavity filter of this embodiment includes: the device comprises a box body, a fine adjustment component and two feed heads 6;
the two feed heads 6 are arranged at the front end of the box body, and a coupling probe 7 is arranged in each feed head 6;
the box body is internally provided with four filtering cavities, namely a first filtering cavity 501 and a fourth filtering cavity 504 which are positioned at the front end of the box body, and a second filtering cavity 502 and a third filtering cavity 503 which are positioned on the rear side surface of the box body, and a partition plate 3 is arranged between every two adjacent filtering cavities;
the two coupling probes 7 respectively penetrate through the box body and are respectively introduced into the first filtering cavity 501 and the fourth filtering cavity 504;
each partition plate 3 is provided with a coupling window, and the coupling window is used for communicating two adjacent filtering cavities with the partition plate 3;
the fine tuning component is arranged in the coupling window and used for adjusting the passband range and the basic performance of the cavity filter.
Preferably, the fine tuning assembly comprises a transverse tuning rod 1, the transverse tuning rod 1 is arranged between the first filter cavity 501 and the fourth filter cavity 504, and the middle part of the transverse tuning rod 1 is fixedly connected with the partition plate 3.
Preferably, the fine adjustment assembly further comprises three window section adjusting rods 8, the window section adjusting rods 8 are arranged in the coupling window which is not provided with the transverse tuning rod 1, the window section adjusting rods 8 are parallel to the partition plate 3, and one end of each window section adjusting rod 8 is movably connected with the box body.
The transmission zero point of the cavity filter without the transverse tuning rod 1 inside is at infinity, the suppression effect at the edge of a pass band is poor, and the filtering effect at a stop band is not optimal, so that partial energy of frequency points near the pass band enters the cavity filter through the feed head 6 and then enters other equipment, and the performance of the filter is influenced. At the moment, the passband selectivity can be improved by increasing the order of the filter, so that the out-of-band rejection characteristic of the cavity filter is improved, but the size and the cost of the cavity filter are increased, and the cavity filter is not beneficial to engineering use.
The box body of this embodiment is divided into upper cover 4 and base 5, all forms by a monoblock metalworking, and wherein first filter chamber 501, second filter chamber 502, third filter chamber 503 and fourth filter chamber 504 all are the recess of cutting out in base 5.
In this embodiment, coupling windows are disposed between the first filter cavity 501 and the second filter cavity 502, between the second filter cavity 502 and the third filter cavity 503, and between the third filter cavity 503 and the fourth filter cavity 504, and the sectional area of the coupling window is adjusted by the window section adjusting rod 8.
In the embodiment, the transverse tuning rod 1 is arranged between the first filtering cavity 501 and the fourth filtering cavity 504 inside the fourth-order cavity filter, and the length, the position and the diameter of the tuning rod are adjusted according to the size of the cavity filter, so that the first filtering cavity 501 and the fourth filtering cavity 504 are coupled, the cavity filter has a transmission zero point near a passband frequency, and the out-of-band rejection characteristic of the cavity filter is improved without increasing the order number and the volume of the filter.
Referring to fig. 4-10, which are further embodiments of the present invention, the cavity filter of this example is 95mm by 93mm by 42.5mm in size, with a passband in the range of 920MHz to 960 MHz.
From the field theory, the following can be taken:
obtaining a coupling coefficient k between adjacent cavities; wherein ε is a dielectric constant, μ is a permeability, E1And E2And H1And H2Respectively the field components inside the two resonant cavities. Accordingly, the coupling coefficient k between adjacent cavities is adjusted by adjusting the window section adjusting rod 8 and the transverse tuning rod 1, and the basic performance of the cavity filter is further adjusted.
Referring to fig. 4 and 5, the transverse tuning rod 1 of the present embodiment plays a role of adding a coupling circuit in an equivalent circuit of the fourth-order cavity resonator 2, and the height, length, and diameter of the transverse tuning rod 1 all affect the performance of the fourth-order cavity resonator 2.
Referring to fig. 6 to 8, in the present embodiment, the height, length, and diameter of the transverse tuning rod 1 are optimized by using simulation software, so as to improve the performance of the cavity filter. The dimension of the tuning rod of the cavity filter is optimized by using HFSS simulation software, and it can be found that when the height of the tuning rod (the distance between the center of the tuning rod and the bottom surface of the cavity filter) is 28.5mm, the transmission zero point is closer to the pass band of the filter, the insertion loss is rapidly reduced outside the pass band, and the out-of-band rejection characteristic of the filter is better; the out-of-band rejection effect of the cavity filter is not obvious when the diameter of the tuning rod is changed, and the radius of the tuning rod can be 1.5mm-2.3 mm; the longer the tuning rod length is, the closer the transmission zero point of the cavity filter is to the passband, the insertion loss also drops rapidly at the frequency near the passband, the tuning rod cannot be lengthened infinitely due to the limitation of the size of the cavity filter, and the tuning rod length of the embodiment is set to be 23.5 mm.
Referring to fig. 9 and 10, by using HFSS simulation software to simulate whether the cavity filter of the present embodiment adds the transverse tuning rod 1, it can be found that after the transverse tuning rod 1 is added, the transmission zero of the cavity filter is near the passband frequency, and the out-of-band rejection level of the cavity filter is significantly improved.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (9)
1. A cavity filter, comprising: the feed device comprises a box body, a fine adjustment assembly and two feed heads;
the two feed heads are arranged on one side of the box body, and a coupling probe is arranged in each feed head;
at least two filtering cavities are arranged in the box body, a partition plate is arranged between every two adjacent filtering cavities, and the two coupling probes penetrate through the box body and are arranged in the two adjacent filtering cavities;
a resonator is arranged in each filtering cavity, a tuning screw is arranged in each resonator, the tuning screw penetrates through the resonators, and two ends of each tuning screw are connected with the box body;
the diaphragm is provided with a coupling window, the fine tuning assembly is arranged in the coupling window, and the fine tuning assembly is used for adjusting the passband range and the basic performance of the cavity filter.
2. The cavity filter of claim 1, wherein the fine tuning assembly comprises a lateral tuning rod, the lateral tuning rod penetrates through the coupling window, and a middle portion of the lateral tuning rod is fixedly connected to the partition.
3. The cavity filter according to claim 2, wherein when the number of the filter cavities is more than two, two of the filter cavities are arranged in the box body in a group of two filter cavities in the transverse direction, and a plurality of groups of two filter cavities are arranged in the longitudinal direction.
4. The cavity filter according to claim 3, wherein the coupling window is disposed on the partition between the adjacent filter cavities, and only one coupling window is disposed between the adjacent filter cavities.
5. The cavity filter according to claim 4, wherein when the coupling window is provided in plurality, the lateral tuning rod is provided only in the coupling window between two of the coupling probes.
6. The cavity filter of claim 5, wherein the fine tuning assembly further comprises a window section adjusting rod, the window section adjusting rod is disposed in the middle of the coupling window without the transverse tuning rod, the window section adjusting rod is parallel to the adjacent partition plate, and one end of the window section adjusting rod is movably connected to the box body.
7. A fourth order cavity filter, comprising: the feed device comprises a box body, a fine adjustment assembly and two feed heads;
the two feed heads are arranged at the front end of the box body, and a coupling probe is arranged in each feed head;
the box body is internally provided with four filtering cavities, namely a first filtering cavity and a fourth filtering cavity which are positioned at the front end of the box body, a second filtering cavity and a third filtering cavity which are positioned on the rear side surface of the box body, and a partition plate is arranged between every two adjacent filtering cavities;
the two coupling probes respectively penetrate through the box body and are respectively introduced into the first filtering cavity and the fourth filtering cavity;
resonators are arranged in the four filter cavities, tuning screws are arranged in the resonators, the tuning screws penetrate through the resonators, and two ends of each tuning screw are connected with the box body;
each partition plate is provided with a coupling window, and the coupling window is used for communicating two filtering cavities adjacent to the partition plate;
the fine tuning component is arranged in the coupling window and used for adjusting the passband range and the basic performance of the cavity filter.
8. The fourth-order cavity filter according to claim 7, wherein the fine tuning assembly comprises a lateral tuning rod, the lateral tuning rod is disposed between the first filtering cavity and the fourth filtering cavity, and a middle portion of the lateral tuning rod is fixedly connected to the partition plate.
9. The fourth-order cavity filter according to claim 8, wherein the fine tuning assembly further comprises three window section adjusting rods, the window section adjusting rods are disposed in the coupling windows without the transverse tuning rods, the window section adjusting rods are parallel to the partition plate, and one ends of the window section adjusting rods are movably connected to the box body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111683360.2A CN114300822A (en) | 2021-12-31 | 2021-12-31 | Cavity filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111683360.2A CN114300822A (en) | 2021-12-31 | 2021-12-31 | Cavity filter |
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| Publication Number | Publication Date |
|---|---|
| CN114300822A true CN114300822A (en) | 2022-04-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202111683360.2A Pending CN114300822A (en) | 2021-12-31 | 2021-12-31 | Cavity filter |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101471472A (en) * | 2007-12-27 | 2009-07-01 | 奥雷通光通讯设备（上海）有限公司 | Coupling structure of filter |
| CN102544650A (en) * | 2012-01-05 | 2012-07-04 | 西安电子科技大学 | Coaxial resonant cavity mixed coupling method |
| CN102683769A (en) * | 2011-06-15 | 2012-09-19 | 吴芬 | Cavity filter, duplexer, combiner and transmission zero frequency debugging method for cavity filter |
| CN203260702U (en) * | 2013-04-16 | 2013-10-30 | 深圳光启创新技术有限公司 | Cavity filter |
| CN213425159U (en) * | 2020-11-09 | 2021-06-11 | 华沣通信科技有限公司 | Coaxial cavity filter of hollow capacitive coupling rod |
-
2021
- 2021-12-31 CN CN202111683360.2A patent/CN114300822A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101471472A (en) * | 2007-12-27 | 2009-07-01 | 奥雷通光通讯设备（上海）有限公司 | Coupling structure of filter |
| CN102683769A (en) * | 2011-06-15 | 2012-09-19 | 吴芬 | Cavity filter, duplexer, combiner and transmission zero frequency debugging method for cavity filter |
| CN102544650A (en) * | 2012-01-05 | 2012-07-04 | 西安电子科技大学 | Coaxial resonant cavity mixed coupling method |
| CN203260702U (en) * | 2013-04-16 | 2013-10-30 | 深圳光启创新技术有限公司 | Cavity filter |
| CN213425159U (en) * | 2020-11-09 | 2021-06-11 | 华沣通信科技有限公司 | Coaxial cavity filter of hollow capacitive coupling rod |
Non-Patent Citations (1)
| Title |
|---|
| 周建梅: ""腔体滤波器耦合结构理论和关键技术的研究"", 《中国优秀硕士学位论文全文数据库信息科技辑》 * |
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Address after: No. 8 Qishan Road, Shiqi Town, Panyu District, Guangzhou City, Guangdong Province, 510000, 150 Applicant after: Radio and TV Measurement and Testing Group Co.,Ltd. Address before: 511450 150, No. 8, Qishan Road, Shiqi Town, Panyu District, Guangzhou City, Guangdong Province Applicant before: GUANGZHOU GRG METROLOGY & TEST Co.,Ltd. |
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Application publication date: 20220408 |