CN103490127B - Three-passband filter - Google Patents
Three-passband filter Download PDFInfo
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- CN103490127B CN103490127B CN201310428908.8A CN201310428908A CN103490127B CN 103490127 B CN103490127 B CN 103490127B CN 201310428908 A CN201310428908 A CN 201310428908A CN 103490127 B CN103490127 B CN 103490127B
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- electric impedance
- step electric
- quarter
- line
- passband filter
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Abstract
A kind of three-passband filter being applied to the communications field disclosed by the invention comprises the dielectric substrate being provided with grounding through hole, be positioned at the main line of dielectric substrate upper surface and be positioned at the metal ground layer of dielectric substrate lower surface, main line is formed by the quarter-wave step electric impedance resonator cascade that two distribute axisymmetricly, two quarter-wave step electric impedance resonators are connected by grounding through hole, two quarter-wave step electric impedance resonators connect I/O feeder line respectively, each step electric impedance resonator comprises three end to end transmission lines, the interlude being positioned at middle transmission line is loaded with open circuited transmission line.This three-passband filter has centre frequency and bandwidth is easy to features such as controlling, frequency selectivity is high, band interval dynamics is high, volume is small-sized.
Description
Technical field
The invention belongs to technical field of micro communication, be specifically related to a kind of compact type three-passband filter of planar microstrip structure.
Background technology
Along with the fast development of multiband, multi-standard wireless communication system, to the high selectivity of multi-band bandpass filter frequency and miniaturizedly propose higher requirement.
Realize the screening of three band signals, traditional method is the screening that employing three single-pass band filters realize respectively to each passband signal, the feature simple possible of this method, but underintegration, cannot meet radio communication small size, light-weighted demand for development.Therefore designing a kind of can " high selectivity, miniaturization " three-passband filter of effective integration be when previous important topic.
The implementation of three-passband filter has a variety of, at present more common structure and corresponding feature as follows: (1) realizes three-passband filter structure by two groups or three groups of resonator parallel connections, adopt public input/output port, often organize resonator and produce a passband or two passbands, the deficiency of this filter construction is that it is complicated, volume is large; (2) realize three-passband filter by introducing transmission zero in single-pass band or double-passband filter, but this filter there is baroque problem equally and design difficulty is larger.
Summary of the invention
The object of the invention is to overcome the problems referred to above of the prior art, provide a kind of structure simple, be convenient to processing and the planar microstrip compact type three-passband filter that frequency selectivity is good, isolation is high.
For solving the problems of the technologies described above, the present invention by the following technical solutions:
A kind of planar microstrip compact type three-passband filter, comprise the dielectric substrate being provided with grounding through hole, be positioned at the main line of dielectric substrate upper surface and be positioned at the metal ground layer of dielectric substrate lower surface, described main line is formed by the quarter-wave step electric impedance resonator cascade that two distribute axisymmetricly, two quarter-wave step electric impedance resonators are connected by grounding through hole, two quarter-wave step electric impedance resonators connect I/O feeder line respectively, it is characterized in that: each step electric impedance resonator comprises three end to end transmission lines, the interlude being positioned at middle transmission line is loaded with open circuited transmission line,
End is positioned at and the transmission line be not connected with grounding through hole is helix structure in described step electric impedance resonator.
Further, described open circuited transmission line is helix structure.
Further, described I/O feeder line is the microstrip line that characteristic impedance is 50 ohm.
Further, described I/O feeder line is tap structure.
Compared with prior art, the beneficial effect of the planar microstrip compact type three-passband filter of the present invention's proposition is as follows:
First, planar microstrip compact type three-passband filter of the present invention realizes by loading open circuited transmission line respectively at two quarter-wave step electric impedance resonators of cascade, after determining quarter-wave step electric impedance resonator, can be control effectively to the centre frequency of passband and bandwidth by the length of controlled loading open-circuit line and loading position;
Secondly, in planar microstrip compact type three-passband filter of the present invention, form electromagnetic coupled between the transmission line of two step electric impedance resonators, grounding through hole is pass through magnetic coupling between two step electric impedance resonators, facts have proved, this structure can produce six transmission zeros near the both sides of filter passband, makes filter have higher frequency selective characteristic and isolation;
Again, planar microstrip compact type three-passband filter of the present invention is planar structure, circuit structure is compact, by the fractional transmission line of open circuited transmission line and step electric impedance resonator is designed to helix structure, further increases space availability ratio, reduces circuit size;
Finally, planar microstrip compact type three-passband filter structure of the present invention is simple, is easy to processing.
Accompanying drawing explanation
Fig. 1 is the structural representation of planar microstrip compact type three-passband filter of the present invention;
Fig. 2 is the frequency response curve of the planar microstrip compact type three-passband filter in embodiment.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
As shown in Figure 1, the planar microstrip compact type three-passband filter in the present embodiment comprise be provided with grounding through hole 11 dielectric substrate 1, be positioned at the main line of dielectric substrate 1 upper surface and be positioned at the metal ground layer 3 of dielectric substrate lower surface.Main line is formed by two the quarter-wave step electric impedance resonator distributed axisymmetricly 21,21 ＇ cascades, and two step electric impedance resonators 21 and 21 ＇ are connected by grounding through hole 11 and are grounded.Step electric impedance resonator 21 comprises three end to end transmission lines 211,212 and 213; Step electric impedance resonator 21 ＇ comprises three end to end transmission line 211 ＇, 212 ＇ and 213 ＇, wherein, electromagnetic coupled is formed between transmission line 212 and 212 ＇ and between 213 and 213 ＇, grounding through hole 11 provides magnetic coupling, effectively can control filter bandwidht by the electromagnetic coupling strengths between adjustment step electric impedance resonator 21 and 21 ＇, effectively can control the outer transmission zero of filter band by electric coupling and magnetic coupling ratio in adjustment electromagnetic coupled simultaneously.The interlude being positioned at transmission line 212 and 212 ＇ in the middle of step electric impedance resonator 21,21 ＇ being loaded with open circuited transmission line 4 and 4 ＇, can effectively the higher order resonances mould of quarter-wave step electric impedance resonator 21 or 21 ＇ being moved to low frequency end by loading open circuited transmission line 4,4.Step electric impedance resonator 21 and 21 ＇ of two cascades form the three-passband filter of the present embodiment together with open circuited transmission line 4,4 ＇, this three-passband filter can realize the screening of three different frequency range signals, makes same radio-frequency front-end can support the work of multiple communication standards of different frequency.
In order to improve space availability ratio further, reduce circuit size, and then reduce filter size, open circuited transmission line 4,4 ＇ here and transmission line 213,213 ＇ all adopts helix structure.
Two quarter-wave step electric impedance resonator 21,21 ＇ connect I/O feeder line 5,5 ＇ respectively, and I/O feeder line 5,5 ＇ in the present embodiment all adopts tap structure, and is the microstrip line that characteristic impedance is 50 ohm.
Figure 2 shows that the frequency response curve of the planar microstrip compact type three-passband filter in the present embodiment, the curve S in figure
11for the characteristic curve of signal port reflection, curve S
21for the transfer curve of signal, as seen from the figure, the centre frequency of the first passband is 1.92GHz, its three dB bandwidth is 6.4%, meets the requirement of gsm system, and insertion loss is 0.9dB, return loss is greater than 17.5dB, and this passband is at 1.66GHz and 2.65GHz place generation two transmission zero Tz
1, Tz
2; The centre frequency of the second passband is 3.50GHz, and its three dB bandwidth is 4.0%, meets the requirement of WIMAX system, and insertion loss is 1.8dB, and return loss is greater than 15.5dB, and this passband is at 3.07GHz and 3.96GHz place generation two transmission zero Tz
3, Tz
4; The centre frequency of the 3rd passband is 5.75GHz, its three dB bandwidth is 2.4%, meets the requirement of WLAN (5.7GHz) system, and insertion loss is 1.9dB, return loss is greater than 19.5dB, and this passband is at 5.40GHz and 6.17GHz place generation two transmission zero Tz
5, Tz
6.Transmission zero Tz
1, Tz
2, Tz
3, Tz
4, Tz
5, Tz
6greatly improve the frequency selectivity of filter, simultaneously transmission zero Tz
2and Tz
3improve the isolation between the first passband and the second passband, transmission zero Tz
4and Tz
5improve the isolation of the second passband and threeway interband.
Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to so special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combination of not departing from essence of the present invention according to these technology enlightenment disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.
Claims (4)
1. a three-passband filter, comprise the dielectric substrate being provided with grounding through hole, be positioned at the main line of dielectric substrate upper surface and be positioned at the metal ground layer of dielectric substrate lower surface, described main line is formed by the quarter-wave step electric impedance resonator cascade that two distribute axisymmetricly, two quarter-wave step electric impedance resonators are connected by grounding through hole, two quarter-wave step electric impedance resonators connect I/O feeder line respectively, it is characterized in that: each step electric impedance resonator comprises three end to end transmission lines, the interlude being positioned at middle transmission line is loaded with open circuited transmission line, end is positioned at and the transmission line be not connected with grounding through hole is helical structure in described step electric impedance resonator.
2. three-passband filter according to claim 1, is characterized in that: described open circuited transmission line is helical structure.
3. three-passband filter according to claim 1, is characterized in that: described I/O feeder line is the microstrip line that characteristic impedance is 50 ohm.
4. the three-passband filter according to claim 1 or 3, is characterized in that: described I/O feeder line is tap structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310428908.8A CN103490127B (en) | 2013-09-18 | 2013-09-18 | Three-passband filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310428908.8A CN103490127B (en) | 2013-09-18 | 2013-09-18 | Three-passband filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103490127A CN103490127A (en) | 2014-01-01 |
| CN103490127B true CN103490127B (en) | 2015-08-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310428908.8A Expired - Fee Related CN103490127B (en) | 2013-09-18 | 2013-09-18 | Three-passband filter |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107317589A (en) * | 2017-06-16 | 2017-11-03 | 京信通信系统（中国）有限公司 | Micro-strip combiner and its radio circuit |
| CN114639930B (en) * | 2022-02-25 | 2023-05-30 | 中国电子科技集团公司第十研究所 | High passband isolation's dual-passband filter |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1529923A (en) * | 2001-06-13 | 2004-09-15 | Resonator and filter comprising same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI353080B (en) * | 2008-03-25 | 2011-11-21 | Ralink Technology Corp | Second order band-pass filter and wireless apparat |
| CN102509823B (en) * | 2011-10-26 | 2015-04-15 | 京信通信系统（中国）有限公司 | Double-passband micro-strip filter |
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2013
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1529923A (en) * | 2001-06-13 | 2004-09-15 | Resonator and filter comprising same |
Non-Patent Citations (5)
| Title |
|---|
| A New Tri-Band Bandpass Filter Based on Stub-Loaded Step-Impedance Resonator;Wei-Yu Chen等;《Microwave and Wireless Components Letters, IEEE》;20120319;第179-181页及图1-图5 * |
| A Wide-Stopped Microstrip Bandpass Filter Using Mixed Electric and Magnetic Coupled Resonators;Fei Cheng等;《Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC), 2013 》;20130725;第66-68页及图4、图5 * |
| Design of a New Tri-Band Microstrip BPF Using Combined Quarter-Wavelength SIRs;Ching-Her Lee等;《IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS》;20061030;第16卷(第11期);全文 * |
| Dual-band bandpass filter using embedded spiral resonator and broadside-coupled meander slot-line;X.Luo等;《ELECTRONICS LETTERS》;20100805;第46卷(第6期);全文 * |
| Transmission-Line Filters With Capacitively Loaded Coupled Lines;Chih-Ming Tsai等;《IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES》;20030429;第51卷(第5期);全文 * |
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| CN103490127A (en) | 2014-01-01 |
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