CN112436255B - anti-5G base station interference filter - Google Patents
anti-5G base station interference filter Download PDFInfo
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- CN112436255B CN112436255B CN202011156662.XA CN202011156662A CN112436255B CN 112436255 B CN112436255 B CN 112436255B CN 202011156662 A CN202011156662 A CN 202011156662A CN 112436255 B CN112436255 B CN 112436255B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/212—Frequency-selective devices, e.g. filters suppressing or attenuating harmonic frequencies
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
- H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
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Abstract
The invention discloses a 5G base station interference resistant filter, which comprises a cavity and a cover plate hermetically connected with the cavity, wherein a plurality of input ports and a plurality of output ports are symmetrically arranged at two sides of the cavity, a dendritic isolation plate is arranged in the cavity, the cavity is symmetrically arranged into a first resonant cavity, a second resonant cavity, a third resonant cavity and a fourth resonant cavity which are sequentially communicated by taking the dendritic isolation plate as a symmetry, a plurality of sections of chain-type rods extend to the output ports from the input ports along the first resonant cavity, the second resonant cavity, the third resonant cavity and the fourth resonant cavity, resonators are arranged on nodes of the plurality of sections of chain-type rods, gaps are reserved between the cavity and the cover plate, heat-conducting silica gel is filled in the gaps, and an electromagnetic shielding film is coated on the inner surface layer of the cover plate. The device designed by the invention can achieve the design targets of low insertion loss, low return loss, high out-of-band rejection performance, high power capacity and smaller size through debugging.
Description
Technical Field
The invention relates to the technical field of microwave communication, in particular to a 5G base station interference resisting filter.
Background
According to the requirement of 5G construction, a 3400 MHz-3500 MHz frequency band is allocated to a Chinese telecommunication 5G base station for use, a 3500 MHz-3600 MHz frequency band is allocated to a Chinese Unicom 5G base station for use, and a C frequency band satellite use frequency band is changed from 3400 MHz-4200 MHz to 3700 MHz-4200 MHz. Because the 5G base station has high transmitting power and adopts the high-gain beam forming antenna, the low-noise frequency conversion amplifier (LNB) can generate saturated interference after the 5G base station strong interference signal working at the frequency band of 3400 MHz-3600 MHz enters the C-frequency band satellite receiving system. In order to solve the problem of interference of a 5G base station working at a frequency band of 3400 MHz-3600 MHz to a satellite earth station at a frequency band C, an anti-5G base station interference filter is required to be designed to suppress a 5G interference signal.
The anti-5G base station interference filter is a device additionally arranged behind a satellite receiving antenna feed source. In order to reduce the influence on the link budget capacity of the satellite receiving system after the filter is added, the filter is required to have the characteristics of low insertion loss and low return loss. In order to reduce the influence of interference signals of the 5G base station and enhance the flexibility of deployment of the 5G base station, the filter is required to have high suppression performance outside a 3700 MHz-4200 MHz passband. The strong interference signal of the 5G base station has high power after being amplified by the satellite receiving antenna, and a filter is required to have the characteristic of high power capacity in order to avoid puncturing related devices. In order to reduce the safety influence on the bearing and wind resistance of the small satellite receiving antenna after the filter is added, the filter is required to have the characteristic of small size.
On one hand, if the insertion loss of filtering is ensured to be small, the stage number N of the filter is less, the quality factor Q of a resonant cavity of the filter is large, and the actual bandwidth BW of the filter is large; on the other hand, a high out-of-band rejection performance is required, the larger the filter order N needs to be. Therefore, the restriction relation exists between the insertion loss and the out-of-band rejection index in the filter design, and the higher the band-pass and out-of-band rejection of the filter is, the more filter stages are required, and the larger the insertion loss is. How to balance the performance of insertion loss and out-of-band rejection by designing a suitable filter structure is a problem to be overcome in the art.
The filter has low insertion loss and high out-of-band rejection performance, and the key technical difficulty of the invention is that the out-of-band rejection is improved by reasonably setting a transmission zero point in the design of the filter, and the insertion loss of equipment is reduced by adjusting the quality factor Q of a resonant cavity of the filter, so that the design goal is realized by the two methods.
Chinese patent, publication No.: CN204361233U, published: 2015, 5.27.5.2015, an anti-interference filter is disclosed, which comprises a shell and a cavity in the shell, wherein one side outside the shell is provided with two joints arranged in the front-back direction, each joint is respectively connected with a front connecting rod and a rear connecting rod arranged in the left-right direction in the cavity, the front connecting rod is provided with at least two resonators at intervals in the left-right direction, and the rear connecting rod is provided with at least two resonators at intervals in the left-right direction; a partition board is arranged between the two connecting rods, an installation space is arranged between the partition board and/or the partition board and the other side face of the shell, a resonator is arranged in the installation space, the number of transmission zero points is small due to the chain design of the resonators in the device, and the band-pass external inhibition performance is low.
Disclosure of Invention
The invention aims to solve the problem of interference of a 5G base station working in a frequency band of 3400-3600 MHz to a satellite earth station in a frequency band C, and provides a 5G base station interference resisting filter with a pass band of 3700-4200MHz, wherein the 5G base station interference resisting filter has the characteristics of low insertion loss, low return loss, high out-of-band rejection performance, high power capacity and small size.
In order to achieve the technical purpose, the invention provides a technical scheme that the 5G base station interference resistant filter comprises a cavity and a cover plate hermetically connected with the cavity, wherein a plurality of input ports and a plurality of output ports are symmetrically arranged on two sides of the cavity, a dendritic isolation plate is arranged in the cavity, the cavity is symmetrically provided with a first resonant cavity, a second resonant cavity, a third resonant cavity and a fourth resonant cavity which are sequentially communicated, a plurality of sections of chain-type rods extend to the output ports from the input ports along the first resonant cavity, the second resonant cavity, the third resonant cavity and the fourth resonant cavity, resonators are arranged on nodes of the plurality of sections of chain-type rods, a gap is reserved between the cavity and the cover plate, heat-conducting silica gel is filled in the gap, and an electromagnetic shielding magnetic film is coated on the inner surface layer of the cover plate.
In this scheme, interference filter is a confined metal cavity, and overall dimension is 122 × 98.5 × 69.9 millimeters, and the clearance intussuseption that leaves between cavity and the apron is filled with heat conduction silicon, can spill the heat through the apron, and the internal surface coating of apron has shielding external electromagnetic interference that electromagnetic shield magnetic film can be fine simultaneously, is provided with the syntonizer on the multisection chain pole, can constitute a plurality of zero points and filter structure, the equipment debugging of being convenient for.
Preferably, the multi-section chain-type rod is a ten-section chain-type rod, the multi-section chain-type rod has eleven nodes, a first resonator, a second resonator, a third resonator, a fourth resonator, a fifth resonator, a sixth resonator, a seventh resonator, an eighth resonator, a ninth resonator, a tenth resonator and an eleventh resonator are sequentially arranged on the nodes of the multi-section chain-type rod extending from the input port to the output port, the fifth resonator is located right below the dendrite spacer, the first resonator is located in the first resonant cavity chamber and close to the input port, and the eleventh resonator is located in the first resonant cavity chamber and close to the output port.
Preferably, the second resonator, the third resonator, the fourth resonator and the fifth resonator form a first CQ topology, and the first CQ topology is disposed in the second resonant cavity chamber. Two transmission zero points are formed on the left side and the right side of the first CQ topological structure, and the band-pass external suppression performance is obviously improved.
Preferably, the seventh resonator, the eighth resonator, the ninth resonator and the tenth resonator form a second CQ topology; the first CQ topology is disposed within the third resonant cavity chamber. Two transmission zero points are formed on the left side and the right side of the second CQ topological structure, and the band-pass external suppression performance is obviously improved.
Preferably, the first CQ topology and the second CQ topology are symmetrically arranged on two sides of the dendrite, and the symmetrically arranged CQ topologies form four transmission zeros outside the band pass. The four transmission zeros can obviously enhance the suppression capability outside the band pass; the design and simulation evaluation of relevant parameters are completed through microwave circuit simulation software according to the out-of-band rejection performance of the CQ topological structure, and the design and simulation evaluation are repeatedly adjusted for many times, and performance indexes are analyzed through a visual curve, so that the design target of the out-of-band rejection performance of the filter is finally realized.
Preferably, a first cross-coupling device is further disposed in the second resonant cavity, the cross-coupling device includes a first cross-coupler and a second cross-coupler, and the first cross-coupler and the second cross-coupler are sequentially connected in series through a flying bar and extend into the semi-sealed cavity of the first CQ topology.
Preferably, a second cross-coupling device is further disposed in the second resonant cavity, the cross-coupling device includes a third cross-coupler and a fourth cross-coupler, and the third cross-coupler and the fourth cross-coupler are sequentially connected in series through a flying bar and extend into the semi-sealed cavity of the second CQ topology.
Preferably, the first resonant cavity and the fourth resonant cavity are identical in structural shape.
Preferably, the second and third resonant chambers are identical in structural shape.
Preferably, the input port and the output port are both waveguide ports WR 229.
The invention has the beneficial effects that: in the design of the filter, the insertion loss of equipment is reduced by adjusting the quality factor Q of the resonant cavity of the filter; the resonant cavity quality factor Q finishes design and simulation evaluation of related parameters through electromagnetic compatibility simulation software, and the main method is to achieve the optimal coupling matching target of the coaxial and waveguide ports of the filter by adjusting parameters such as the distance between the resonator and the cavity; through repeated adjustment design and simulation evaluation, the performance indexes are analyzed through a visual curve, and finally the design target of the out-of-band rejection performance of the filter finally reaches the design target of wide pass band frequency (3700 and 4200MHz), low insertion loss (less than or equal to 0.4dB), low return loss (less than or equal to 20.8dB), high out-of-band rejection performance (75dB), high power capacity (more than or equal to 500W) and small size.
Drawings
Fig. 1 is a schematic structural diagram of a filter for resisting 5G base station interference according to the present invention.
Fig. 2 is a graph of simulation results of a 5G base station interference resistant filter of the present invention.
FIG. 3 is a model diagram of an electromagnetic compatibility simulation design of a 5G base station interference resistant filter according to the present invention.
The notation in the figure is:
Detailed Description
For the purpose of better understanding the objects, technical solutions and advantages of the present invention, the following detailed description of the present invention with reference to the accompanying drawings and examples should be understood that the specific embodiment described herein is only a preferred embodiment of the present invention, and is only used for explaining the present invention, and not for limiting the scope of the present invention, and all other embodiments obtained by a person of ordinary skill in the art without making creative efforts shall fall within the scope of the present invention.
Example 1:
as shown in fig. 1, a schematic structural diagram of a 5G base station interference resistant filter includes a main body including a cavity and a cover plate hermetically connected to the cavity, a plurality of input ports and a plurality of output ports are symmetrically disposed at two sides of the cavity, a dendrite spacer is disposed in the cavity, the cavity is symmetrically disposed into a first resonant chamber, a second resonant chamber, a third resonant chamber, and a fourth resonant chamber, which are sequentially communicated with each other, a plurality of sections of chain-like rods extend from the input ports to the output ports along the first resonant chamber, the second resonant chamber, the third resonant chamber, and the fourth resonant chamber, resonators are disposed at nodes of the plurality of sections of chain-like rods, a gap is left between the cavity and the cover plate, the gap is filled with a silica gel for heat conduction, and an electromagnetic shielding magnetic film is coated on an inner surface layer of the cover plate; both the input port and the output port are waveguide ports WR 229; the first resonance cavity and the fourth resonance cavity are identical in structural shape; the second resonant cavity and the third resonant cavity are identical in structural shape.
In this embodiment, the interference filter is a closed metal cavity, the overall dimension is 122 × 98.5 × 69.9 mm, the gap left between the cavity and the cover plate is filled with heat-conducting silicon, heat can be dissipated through the cover plate, meanwhile, the inner surface of the cover plate is coated with an electromagnetic shielding magnetic film, so that external electromagnetic interference can be well shielded, and the multi-section chain-type rod is provided with a resonator, so that a plurality of zero points and a filter structure can be formed, and the debugging of equipment is facilitated.
The multi-section chain type rod is a ten-section chain type rod, the multi-section chain type rod is provided with eleven nodes, a first resonator, a second resonator, a third resonator, a fourth resonator, a fifth resonator, a sixth resonator, a seventh resonator, an eighth resonator, a ninth resonator, a tenth resonator and an eleventh resonator are sequentially arranged on the nodes of the multi-section chain type rod extending from the input port to the output port, the fifth resonator is located right below the dendritic isolation plate, the first resonator is located in the first resonant cavity chamber and close to the input port, and the eleventh resonator is located in the first resonant cavity chamber and close to the output port.
The second resonator, the third resonator, the fourth resonator and the fifth resonator form a first CQ topological structure, and the first CQ topological structure is arranged in the second resonant cavity chamber; the seventh resonator, the eighth resonator, the ninth resonator and the tenth resonator form a second CQ topological structure; the first CQ topology is arranged in a third resonant cavity chamber; the first CQ topological structure and the second CQ topological structure are symmetrically arranged on two sides of the dendritic isolation board, and the symmetrically arranged CQ topological structures enable four transmission zeros to be generated outside a band pass (3700 and 4200 MHz). The outer shape forms four transmission zeros. The four transmission zeros can obviously enhance the suppression capability outside the band pass; the design and simulation evaluation of relevant parameters are completed by the out-of-band rejection performance of the CQ topological structure through microwave circuit simulation software, the design and simulation evaluation are repeatedly adjusted for many times, the performance index is analyzed through a visual curve, and the design target of the out-of-band rejection performance of the filter is finally realized, and a filter model established in the electromagnetic compatibility simulation design software is shown in figure 3, and parameters such as the distance between a resonator 19 and a cavity 18 are designed through adjustment. As shown in the circuit simulation result curve of FIG. 2, it can be seen that the design index of the out-of-band rejection performance greater than 75dB is realized in the 5G communication frequency band of 3400 MHz-3600 MHz.
A first cross coupling device is further arranged in the second resonant cavity and comprises a first cross coupler and a second cross coupler, and the first cross coupler and the second cross coupler are sequentially connected in series through flying rods and extend into a semi-sealed cavity of the first CQ topological structure; and a second cross coupling device is also arranged in the second resonant cavity chamber, and comprises a third cross coupler and a fourth cross coupler which are sequentially connected in series through a flying rod and extend into the semi-sealed cavity of the second CQ topological structure.
The mathematical theoretical formula for adjusting the quality factor in the electromagnetic compatibility simulation design model diagram is as follows:
the filter insertion loss is calculated as formula (1):
in equation (1):
insertion loss (dB)
N: order of filter
F0: center frequency of filter
Q: quality factor of filter resonant cavity
BW: actual bandwidth of the filter
Formula (1) shows that to ensure small insertion loss of filtering, the number of filter stages N is small, the quality factor Q of the filter cavity is large, and the actual bandwidth BW of the filter is large.
The filter out-of-band rejection performance is calculated as formula (2):
T＝10*log(1+ε*(cosh(N*acosh(F))2) Formula (2)
In equation (2):
t: out-of-band rejection performance (dB)
Epsilon: in-band fluctuation
N: order of filter
F: suppressing frequency
The suppression frequency F in equation (2) is calculated as in equation (3):
in equation (3):
Δ F: bandwidth of operation
F0: center frequency
F3: cut-off frequency
As can be seen from equation (2), the higher the out-of-band rejection performance is required, the larger the filter order N is required. Therefore, the restriction relation exists between the insertion loss and the out-of-band rejection index in the filter design, the higher the out-of-band rejection of the filter is, the more the filter stages are needed, and the larger the insertion loss is, and the insertion loss of the equipment is reduced by adjusting the quality factor Q of the resonant cavity of the filter in the filter design; the resonant cavity quality factor Q finishes design and simulation evaluation of related parameters through electromagnetic compatibility simulation software, and the main method is to achieve the optimal coupling matching target of the coaxial and waveguide ports of the filter by adjusting parameters such as the distance between the resonator and the cavity.
The above-mentioned embodiments are preferred embodiments of the anti-5G base station interference filter of the present invention, and not intended to limit the scope of the present invention, and the scope of the present invention includes and is not limited to the embodiments, and all equivalent changes in shape and structure according to the present invention are within the scope of the present invention.
Claims (7)
1. A5G base station interference resistant filter comprises a cavity and a cover plate hermetically connected with the cavity, and is characterized in that a plurality of input ports and a plurality of output ports are symmetrically arranged on two sides of the cavity, dendritic isolation plates are arranged in the cavity, the cavity is symmetrically arranged into a first resonant cavity, a second resonant cavity, a third resonant cavity and a fourth resonant cavity which are sequentially communicated, a plurality of sections of chain-type rods extend to the output ports from the input ports along the first resonant cavity, the second resonant cavity, the third resonant cavity and the fourth resonant cavity, resonators are arranged on nodes of the plurality of sections of chain-type rods, gaps are reserved between the cavity and the cover plate, heat-conducting silica gel is filled in the gaps, and an electromagnetic shielding film is coated on the inner surface layer of the cover plate;
the multi-section chain type rod is a ten-section chain type rod, the multi-section chain type rod is provided with eleven nodes, and a first resonator, a second resonator, a third resonator, a fourth resonator, a fifth resonator, a sixth resonator, a seventh resonator, an eighth resonator, a ninth resonator, a tenth resonator and an eleventh resonator are sequentially arranged on the nodes of the multi-section chain type rod extending from the input port to the output port;
the seventh resonator, the eighth resonator, the ninth resonator and the tenth resonator form a second CQ topological structure; the second CQ topology is arranged in a third resonant cavity chamber;
the second resonator, the third resonator, the fourth resonator and the fifth resonator form a first CQ topological structure, and the first CQ topological structure is arranged in the second resonant cavity chamber;
the first CQ topological structure and the second CQ topological structure are symmetrically arranged on two sides of the dendritic isolation plate;
the first resonator is located in the first resonant chamber and the eleventh resonator is located in the fourth resonant chamber.
2. The filter of claim 1, wherein the filter is configured to resist interference from 5G base stations:
the symmetrical CQ topology results in four transmission zeros outside the bandpass.
3. The filter of claim 1, wherein the filter is configured to resist interference from 5G base stations:
and a first cross coupling device is also arranged in the second resonant cavity and comprises a first cross coupler and a second cross coupler, and the first cross coupler and the second cross coupler are sequentially connected in series through flying rods and extend into the semi-sealed cavity of the first CQ topological structure.
4. The filter of claim 3, wherein the filter is configured to resist interference from 5G base stations:
and a second cross coupling device is also arranged in the second resonant cavity and comprises a third cross coupler and a fourth cross coupler, and the third cross coupler and the fourth cross coupler are sequentially connected in series through flying rods and extend into the semi-sealed cavity of the second CQ topological structure.
5. The filter of claim 1, wherein the filter is configured to resist interference from 5G base stations:
the first resonant cavity and the fourth resonant cavity are identical in structural shape.
6. The filter of claim 1, wherein the filter is configured to resist interference from 5G base stations:
the second resonance cavity and the third resonance cavity are identical in structural shape.
7. The filter of claim 1, wherein the filter is configured to resist interference from 5G base stations: the input and output ports are waveguide ports WR 229.
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| CN109888444A (en) * | 2019-04-17 | 2019-06-14 | 江苏贝孚德通讯科技股份有限公司 | Tunable filter and adjustable duplexer |
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| US5841330A (en) * | 1995-03-23 | 1998-11-24 | Bartley Machines & Manufacturing | Series coupled filters where the first filter is a dielectric resonator filter with cross-coupling |
| KR100313717B1 (en) * | 1999-09-13 | 2001-11-15 | 최춘권 | Band Pass Filter of Dielectric Resonator Type Having Symmetrically Upper and Lower Notch Points |
| CN202094257U (en) * | 2011-05-30 | 2011-12-28 | 南京东恒通信科技有限公司 | GSM (Global System for Mobile Communications) base station filter |
| CN107615577B (en) * | 2015-12-30 | 2020-03-24 | 深圳市大富科技股份有限公司 | Resonance rod assembly, cavity filter and communication equipment comprising cavity filter |
| CN110854489A (en) * | 2019-11-25 | 2020-02-28 | 成都赛纳赛德科技有限公司 | Waveguide cavity filter |
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| CN109888444A (en) * | 2019-04-17 | 2019-06-14 | 江苏贝孚德通讯科技股份有限公司 | Tunable filter and adjustable duplexer |
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| Title |
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| 湖北大学学报;刘哲伟等;《湖北大学学报》;20190304;第41卷(第2期);第163-167、181页 * |
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