CN209766611U - Miniature cavity filter for digital optical fiber repeater - Google Patents
Miniature cavity filter for digital optical fiber repeater Download PDFInfo
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- CN209766611U CN209766611U CN201822253605.8U CN201822253605U CN209766611U CN 209766611 U CN209766611 U CN 209766611U CN 201822253605 U CN201822253605 U CN 201822253605U CN 209766611 U CN209766611 U CN 209766611U
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Abstract
The utility model discloses a miniaturized cavity filter for a digital optical fiber repeater, which comprises a filter cavity (1) and a filter cover plate (2), wherein the filter cavity (1) and the filter cover plate (2) form a band-pass filtering unit (3), the band-pass filtering unit (3) comprises 6 coaxial resonant cavities (4), and the coaxial resonant cavities (4) comprise coaxial resonant rods (5); the non-adjacent coaxial resonant cavities (4) are separated by an isolation rib (6), and the adjacent coaxial resonant cavities (4) are separated by a coupling window (7); a first coaxial resonant cavity (8) of the band-pass filtering unit is communicated with a signal input port (9), and a sixth coaxial resonant cavity (10) of the band-pass filtering unit is communicated with a signal output port (11); a cross-coupling structure (12) is arranged between the third resonance rod and the sixth resonance rod. The utility model discloses beneficial effect does: the cross-coupling structure is adopted, the structure is compact, the performance is excellent, and the miniaturization of the digital optical fiber repeater is facilitated.
Description
Technical Field
The utility model relates to a digital communication equipment field especially relates to a digital optic fibre repeater is with miniaturized cavity filter.
Background
With the rapid development of mobile communication business in China, the number of mobile communication users is continuously increased, so that cellular planning is smaller and smaller, and base station positions are lower and lower; on the other hand, with the high-rise of urban construction, high-rise buildings are emerging continuously, and shadow areas of mobile communication signals are formed behind or in the middle of the high-rise buildings due to the shadow effect of wireless transmission. In addition, during the construction process of the mobile base station, the main lobe of the antenna radiation field pattern has a large downward inclination angle due to the interference problem of the adjacent cells, so that the signal can not be effectively received by the middle upper part of a high-rise building. In addition, due to the shielding effect of buildings and the like on electromagnetic waves, mobile communication signals cannot be normally received in some closed large buildings such as tunnels, subways, underground malls, entertainment cities, parking lots, hotels, office buildings and the like. The digital optical fiber repeater is a brand new system solution for extending the radio frequency part of a base station to serve a plurality of cells by means of digital processing, digital optical transmission, software radio technology and the like, effectively overcomes some technical defects and shortcomings of the original analog optical fiber repeater, and increasingly becomes a necessary choice in the process of network construction and optimization.
The CDMA cavity filter is positioned in a far-end machine of the CDMA optical fiber repeater with diversity function, a receiving antenna in a communication system sends a received electric signal into the band-pass filter, the band-pass filter filters a downlink signal and other interference signals and then accesses the uplink signal into an independent uplink diversity receiving radio frequency link, the uplink signal is transmitted to a near end after being subjected to series processing such as amplification, photoelectric conversion, modulation and the like, and the uplink signal is sent to a base station diversity interface for receiving after being subjected to corresponding radio frequency processing at the near end. Therefore, a base station double-antenna receiving link is formed, so that the base station is more sensitive to receiving mobile phone signals, and mobile phone signals farther away from the base station can be transmitted to the base station in a coverage range.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome prior art's shortcoming, provide a resonance unit few, small, the outband restraines height, is applied to the miniaturized CDMA cavity filter of diversity reception digital optic fibre repeater.
The purpose of the utility model is realized through the following technical scheme: a miniaturized cavity filter for a digital optical fiber repeater comprises a filter cavity and a filter cover plate; the band-pass filtering unit comprises six coaxial resonant cavities, and the coaxial resonant cavities comprise CDMA resonant rods; the non-adjacent coaxial resonant cavities are separated by an isolation rib, and the adjacent coaxial resonant cavities are separated by a coupling window; the first resonant cavity of the band-pass filtering unit is communicated with the signal input port, and the sixth resonant cavity of the band-pass filtering unit is communicated with the signal output port; according to design parameter requirements, a cross coupling structure is arranged between the third resonance rod and the sixth resonance rod, the left side and the right side of the passband comprise a pair of transmission zeros, a double-pole structure is formed, and the double-pole structure has the characteristics of few resonance units, small size, high out-of-band rejection and the like.
The band-pass filtering unit of the miniaturized cavity filter for the digital optical fiber repeater is a CDMA800 uplink signal band-pass filtering unit, six resonance rods are arranged in the band-pass filtering unit, and a signal input port to a signal input port sequentially pass through a first resonance rod, a second resonance rod, a third resonance rod, a fourth resonance rod, a fifth resonance rod and a sixth resonance rod.
Coupling screws are arranged between the coupling windows of the miniaturized cavity filter for the digital optical fiber repeater.
The size of the resonance rod of the miniaturized cavity filter for the digital optical fiber repeater is 43.5mm in height, 10mm in outer diameter, 8mm in inner diameter and 25mm in disc diameter of the resonance rod.
In the band-pass filtering unit of the miniaturized cavity filter for the digital optical fiber repeater, the sizes of coupling windows through which signals sequentially pass from a signal input port to a signal output port are as follows: 18.5mm, 15.5mm, 15mm, 15.5mm, 18.5mm, realize the band-pass filtering function to CDMA band-pass signal, namely passband 824-835MHz signal.
And a cross coupling structure is arranged between the third resonance rod and the sixth resonance rod.
The utility model has the advantages of it is following: the utility model provides a miniaturized cavity filter for a digital optical fiber repeater, which comprises a filter cavity and a filter cover plate, wherein the cavity and the cover plate form a band-pass filtering unit; the band-pass filter unit comprises 6 coaxial resonant cavities, and the coaxial resonant cavities comprise CDMA resonant rods, so that an uplink signal received by the receiving antenna is sent into the band-pass filter, the band-pass filter filters a downlink signal and other interference signals and then accesses the uplink signal into an independent uplink diversity receiving radio frequency link, a base station double-antenna receiving link is formed, and the diversity receiving function is realized in the optical fiber digital repeater system. The CDMA filter comprises a cross coupling structure, has the characteristics of less resonance units, small volume, high out-of-band rejection and the like, and is beneficial to the miniaturization of a repeater system.
Drawings
Fig. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of a bandpass filter unit shown in FIG. 1;
In the figure, 1-a filter cavity, 2-a filter cover plate, 3-a band-pass filtering unit, 4-coaxial resonant cavities, 5-coaxial resonant rods, 6-isolation ribs, 7-coupling windows, 8-a first coaxial resonant cavity, 9-a signal input port, 10-a sixth coaxial resonant cavity, 11-a signal output port, 12-a cross-coupling structure, 13-a coupling screw and 14-a resonant rod disk.
Detailed Description
The invention will be further described with reference to the accompanying drawings, but the scope of the invention is not limited to the following description.
As shown in fig. 1-2, a miniaturized cavity filter for a digital optical fiber repeater, which comprises a filter cavity 1 and a filter cover plate 2, is characterized in that: the cavity 1 and the cover plate 2 form a band-pass filtering unit 3; the band-pass filtering unit 3 comprises 6 coaxial resonant cavities 4, the coaxial resonant cavities 4 comprise coaxial resonant rods 5, and the coaxial resonant rods 5 are provided with resonant rod disks 14; the non-adjacent coaxial resonant cavities 4 are separated by isolation ribs 6, and the adjacent coaxial resonant cavities 4 are separated by coupling windows 7; the first coaxial resonant cavity 8 of the band-pass filtering unit is communicated with the signal input port 9, the sixth coaxial resonant cavity 10 of the band-pass filtering unit is communicated with the signal output port 11, and a cross-coupling structure 12 is arranged between the third resonant rod and the sixth resonant rod.
A digital optic fibre repeater is with miniaturized cavity filter's band-pass filter unit 3 is CDMA800 upward signal band-pass filter unit, establishes six coaxial resonance poles 5 in, signal input port to signal input port loop through first resonance pole, second resonance pole, third resonance pole, fourth resonance pole, fifth resonance pole, sixth resonance pole, first resonance pole, second resonance pole, third resonance pole, fourth resonance pole, fifth resonance pole, sixth resonance pole encircle cross coupling structure 12 anticlockwise in proper order and distribute.
The number of coaxial resonant rods 5 in the band-pass filtering unit 3 is the order of the band-pass filter, and when the order is increased, the out-of-band rejection is increased, but the insertion loss is deteriorated; as the bandwidth increases, the rejection near the passband decreases, but the insertion loss becomes better. The order of the band-pass filter cavity is six according to the rectangular coefficient requirement. The size of the resonant rod determines the passband center frequency of the filter, and the cavity cover plate, the tuning screw and the open end of the resonant rod form a loading capacitor, so that the size of the coaxial resonant cavity and the size of the resonant rod can be effectively shortened by the capacitor loading coaxial resonant cavity structure, specific factors such as the quality factor and the power capacity of the coaxial resonant cavity are considered, the size of each coaxial resonant rod is obtained after HFSS simulation optimization of three-dimensional electromagnetic simulation software, the height of each coaxial resonant rod is 43.5mm, the outer diameter of each coaxial resonant rod is 10mm, the inner diameter of each coaxial resonant rod is 8mm, and the diameter of a disc of each resonant rod is 25 mm.
The band-pass filtering unit 3 adopts a coupling coaxial resonant cavity structure, and starts from a low-pass prototype filter, and realizes the mutual cascade connection of the resonant cavities by an impedance converter through frequency conversion, thereby obtaining each performance index of the band-pass filter. The band-pass filter cavity is based on the direct coupling cavity filter theory, and a transmission curve of Chebyshev function response is realized by cascading multiple stages of coaxial resonant cavities. The coaxial resonant cavity is a quarter-wavelength coaxial line with one short-circuited end, the equivalent circuit of the coaxial resonant cavity is a parallel resonant circuit, the resonant circuit can achieve higher quality factor because the electromagnetic field energy of the resonant circuit is almost completely sealed in the cavity and almost has no radiation loss, and the coaxial resonant cavity filter has the characteristics of small insertion loss, high out-of-band suppression, high power bearing and the like.
Coupling screws 13 are arranged on the coupling windows 7, and the coupling screws 13 penetrate into the filter cavity 1 from the lower part of the filter cover plate 2 and are used for adjusting the coupling strength, so that the length and the diameter of the coupling screws 13 can be increased, and the coupling strength among the coaxial resonant cavities can be increased. The coupling strength of each coaxial resonant rod determines the bandwidth of the filtering passband, the band-pass filtering cavity in the utility model adopts windowing between coaxial resonant cavities to form magnetic coupling, the protruding part of the isolation rib in each filtering cavity is the coupling windowing part between the resonant cavities, the larger the window is, the stronger the coupling degree is, the corresponding coupling coefficient is confirmed by utilizing the simulation of HFSS simulation software, the method is that for the mutually coupled double-cavity structure, scanning the parameters of the coupling structure size to obtain a group of corresponding coupling window size curves when the size of the coupling window changes, the size of the coupling window is selected according to the point of the corresponding coupling coefficient, in the band-pass filter unit 3, the signal passes through each coupling window 7 from the signal input port 9 to the signal output port 11 in turn, the sizes of the first coupling window, the second coupling window, the third coupling window, the fourth coupling window and the fifth coupling window are respectively as follows: 18.5mm, 15.5mm, 15mm, 15.5mm, 18.5 mm.
The utility model discloses the theory of operation does: when the access antenna end receives a signal, the signal is input into a CDMA band-pass filter cavity consisting of six CDMA resonant rods through a CDMA band-pass signal input port, and the CDMA band-pass filter cavity filters out-of-band signals in CDMA uplink signals and then outputs the out-of-band signals from a signal output port 11; the band-pass filter filters the downlink signal and other interference signals, then the uplink signal is accessed into an independent uplink diversity reception radio frequency link, and then the uplink signal is transmitted to the near end after series processing, and is transmitted to the diversity interface of the base station for reception after the near end is processed by the corresponding radio frequency. Thus, a base station double-antenna receiving link is formed, the influence of channel fading is reduced, and the reliability of transmission and the sensitivity of base station receiving are improved. The CDMA band-pass filter has compact structure and excellent performance index, and is favorable for the miniaturization of a diversity reception CDMA repeater system.
Claims (7)
1. The utility model provides a miniaturized cavity filter is used to digital optic fibre repeater which characterized in that: the filter comprises a filter cavity (1) and a filter cover plate (2), wherein the filter cavity (1) and the filter cover plate (2) are combined to form a band-pass filtering unit (3); 6 coaxial resonant cavities (4) are arranged in the band-pass filtering unit (3), coaxial resonant rods (5) are arranged in the coaxial resonant cavities (4), and resonant rod discs (14) are arranged on the coaxial resonant rods (5); the non-adjacent coaxial resonant cavities (4) are separated by an isolation rib (6), and the adjacent coaxial resonant cavities (4) are separated by a coupling window (7); a first coaxial resonant cavity (8) of the band-pass filtering unit (3) is communicated with a signal input port (9), and a sixth coaxial resonant cavity (10) of the band-pass filtering unit (3) is communicated with a signal output port (11); a cross coupling structure (12) is arranged between the third resonance rod and the sixth resonance rod of the band-pass filtering unit (3).
2. the miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: the band-pass filtering unit (3) is a CDMA800 uplink signal band-pass filtering unit.
3. The miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: the coaxial resonant rod (5) passing between the signal input port (9) and the signal output port (11) is sequentially a first resonant rod, a second resonant rod, a third resonant rod, a fourth resonant rod, a fifth resonant rod and a sixth resonant rod.
4. The miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: coupling screws (13) are arranged between the coupling windows (7).
5. The miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: the height of the coaxial resonance rod (5) is 43.5mm, the outer diameter is 10mm, and the inner diameter is 8 mm.
6. The miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: the resonance rod disc (14) has a diameter of 25 mm.
7. The miniaturized cavity filter for the digital optical fiber repeater according to claim 1, wherein: in the band-pass filtering unit (3), the sizes of coupling windows (7) through which signals sequentially pass from a signal input port (9) to a signal output port (11) are as follows: 18.5mm, 15.5mm, 15mm, 15.5mm, 18.5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822253605.8U CN209766611U (en) | 2018-12-29 | 2018-12-29 | Miniature cavity filter for digital optical fiber repeater |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822253605.8U CN209766611U (en) | 2018-12-29 | 2018-12-29 | Miniature cavity filter for digital optical fiber repeater |
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| CN209766611U true CN209766611U (en) | 2019-12-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113131898A (en) * | 2019-12-30 | 2021-07-16 | 深圳市大富科技股份有限公司 | Filter and communication equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113131898A (en) * | 2019-12-30 | 2021-07-16 | 深圳市大富科技股份有限公司 | Filter and communication equipment |
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