CN103762404B - Double-frequency-band filter - Google Patents
Double-frequency-band filter Download PDFInfo
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- CN103762404B CN103762404B CN201310751861.9A CN201310751861A CN103762404B CN 103762404 B CN103762404 B CN 103762404B CN 201310751861 A CN201310751861 A CN 201310751861A CN 103762404 B CN103762404 B CN 103762404B
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- passband
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Abstract
The invention discloses a double-frequency-band filter. The double-frequency-band filter comprises an upper microstrip line, a middle medium substrate and a bottom metal floor, wherein the middle medium substrate is provided with a first grounding through hole, a second grounding through hole and a third grounding through hole, the microstrip line comprises two levels of first passband resonance units which are distributed symmetrically, two levels of second passband resonance units which are distributed symmetrically and two input/output feeder lines, the second passband resonance units are embedded inside the first passband resonance units, a first passband of the filter is composed of the two levels of first passband resonance units, and a second passband of the filter is composed of the two levels of second passband resonance units. According to the double-frequency-band filter, good double-frequency property of the filter is achieved, the structure of the filter is more compact, and the problem that a traditional double-frequency-band filter is complicated in structure, large in size and the like is solved.
Description
Technical field
The invention belongs to technical field of micro communication, be specifically related to the dual frequency filter of a kind of compact conformation, high selectivity, high-isolation.
Background technology
Along with the fast development of multiband, multi-standard wireless communication technology, the designing requirement of multi-band bandpass filter is become more and more higher.The design of traditional double-passband filter comprises: single-pass band, by introducing transmission zero in single-pass band filter, is divided into dual-passband by (1), and this filter construction is complicated, and design difficulty is large; (2) adopt stepped impedance bimodulus characteristics design double-passband filter, each passband of this filter is difficult to independent control; (3) by realizing double-passband filter at pass filter and stop-band filter cascade, this filter construction is complicated, size is large; (4) adopt the parallel connection of two single-pass band filters to realize double-passband filter, this filter advantage is to control separately each passband, but traditional implementation same structure is complicated, volume is large.Therefore, how to design high selectivity, miniaturization, high-isolation double-passband filter more and more by the concern of people.
Summary of the invention
The object of the invention is to overcome the problems referred to above of the prior art, a kind of compact conformation, miniaturization and have the dual frequency filter of high selectivity, high isolation are provided.
For solving the problems of the technologies described above, the present invention by the following technical solutions:
A kind of dual frequency filter, comprise upper strata microstrip line, be provided with the first grounding through hole, the intermediate medium substrate of the second grounding through hole and the 3rd grounding through hole and underlying metal floor, described microstrip line comprises the first symmetrical passband resonant element of two-stage, the symmetrical second passband resonant element of two-stage and two I/O feeder lines; Described first passband resonant element is formed by the first grounding through hole and with the short-circuited transmission line of its cascade, rectangle closed annular transmission line; Second passband resonant element is formed by the second grounding through hole or the 3rd grounding through hole and with the short-circuited transmission line of the second grounding through hole or the 3rd grounding through hole cascade, rectangle closed annular transmission line; The rectangle closed annular transmission line that described second passband resonant element is embedded in the first passband resonant element is inner, and two I/O feeder lines are connected on the short-circuited transmission line of the first passband resonant element.
Further, described I/O feeder line adopts tap structure.
Further, the characteristic impedance of described I/O feeder line is 50 ohm.
Compared with prior art, the invention has the beneficial effects as follows:
First, the microstrip line of dual frequency filter of the present invention comprises the first symmetrical passband resonant element of two-stage, the symmetrical second passband resonant element of two-stage, and the rectangle closed annular transmission line that the second passband resonant element is embedded in the first passband resonant element is inner, two-stage first passband resonant element forms the first passband of filter, two-stage second passband resonant element forms the second passband of filter, this design makes filter obtain good dual frequency characteristics on the one hand, make the structure of filter compacter simultaneously, overcome conventional dual band filter construction complicated, the problems such as volume is heavy,
Secondly, facts have proved, dual frequency filter of the present invention can produce 5 transmission zeros at passband annex, and the generation of transmission zero effectively can improve the isolation characteristic between the frequency selective characteristic of filter and passband.
Accompanying drawing explanation
Fig. 1 is the structural representation of dual frequency filter of the present invention;
Fig. 2 is the frequency response curve of dual frequency filter embodiment of the present invention.
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 dual frequency filter in the present embodiment comprises upper strata microstrip line 1, is provided with intermediate medium substrate 2 and the underlying metal floor 3 of the first grounding through hole 21, second grounding through hole 22 and the 3rd grounding through hole 23;
Microstrip line 1 comprises the first symmetrical passband resonant element 11,11 ＇ of two-stage, two-stage symmetrical second passband resonant element 12,12 ＇ and two I/O feeder line 13,13 ＇;
First passband resonant element 11 is made up of the short-circuited transmission line 111 of the first grounding through hole 21 and cascade, rectangle closed annular transmission line 112;
First passband resonant element 11 ＇ by the first grounding through hole 22 and cascade short-circuited transmission line 111 ＇, rectangle closed annular transmission line 112 ＇ and form;
Second passband resonant element 12 is made up of the short-circuited transmission line 121 of the second grounding through hole 22 and cascade, rectangle closed annular transmission line 122;
Second passband resonant element 12 ＇ is made up of short-circuited transmission line 121 ＇, rectangle closed annular transmission line 122 ＇ of the 3rd grounding through hole 23 and cascade;
The rectangle closed annular transmission line 112 that second passband resonant element 12 is embedded in the first passband resonant element 11 is inner, rectangle closed annular transmission line 112 ＇ that second passband resonant element 12 ＇ is embedded in the first passband resonant element 11 ＇ is inner, this structure makes the structure of filter compacter, overcomes the problems such as conventional dual band filter construction is complicated, volume is heavy;
By between the rectangle closed hoop transmission line 112 of dual frequency filter in the present embodiment and rectangle closed hoop transmission line 112 ＇, rectangle closed hoop transmission line 112 and rectangle closed hoop transmission line 212 and introduce electric coupling between rectangle closed hoop transmission line 112 ＇ and rectangle closed hoop transmission line 212 ＇, simultaneously at the first grounding through hole 21 place and the second grounding through hole 22, magnetic coupling is introduced between the 3rd grounding through hole 23, by magnetic coupling, the mutual elimination effect of electric coupling and transmission line harmonic effect just can produce 5 transmission zeros at the near pass-band of this dual frequency filter, improve frequency selectivity and the interband isolation of filter.
Article two, I/O feeder line 13,13 ＇ is connected on short-circuited transmission line 111,111 ＇ of the first passband resonant element 11,11 ＇.
Preferably, I/O feeder line 13,13 ＇ in the present embodiment adopts tap structure, and characteristic impedance is the microstrip line of 50 ohm.
Fig. 2 is the frequency response curve of the dual frequency filter of the present embodiment, comprises two curve S in figure
11, S
21, curve S
11the characteristic curve of signal port reflection, curve S
21it is the transfer curve of signal.From map analysis, the centre frequency of the first passband is 2.46GHz, and its three dB bandwidth is 12.2%, meets the requirement of wlan system, and insertion loss is 0.71dB, and return loss is greater than 27.1dB, and this passband is at 2.08GHz and 3.70GHz place generation two transmission zero TZ
1, TZ
2; The centre frequency of the second passband is 5.21GHz, and its three dB bandwidth is 4.4%, meets the requirement of wlan system, and insertion loss is 0.8dB, and return loss is greater than 15.2dB, and this passband is at 4.93GHz, 6.05GHz and 8.9GHz place generation three transmission zero TZ
3, TZ
4, TZ
5; Meanwhile, transmission zero TZ
2and TZ
3improve the isolation between the first passband and the second passband.
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 (3)
1. a dual frequency filter, it is characterized in that: comprise upper strata microstrip line, be provided with the first grounding through hole, the intermediate medium substrate of the second grounding through hole and the 3rd grounding through hole and underlying metal floor, described microstrip line comprises the second symmetrical passband resonant element of the first symmetrical passband resonant element of two-stage, two-stage and two I/O feeder lines; Described two-stage first passband resonant element is all positioned at the same side of described two I/O feeder lines; Described first passband resonant element is formed by the first grounding through hole and with the short-circuited transmission line of its cascade, rectangle closed annular transmission line, second passband resonant element is formed by the second grounding through hole or the 3rd grounding through hole and with the short-circuited transmission line of the second grounding through hole or the 3rd grounding through hole cascade, rectangle closed annular transmission line, the rectangle closed annular transmission line that described second passband resonant element is embedded in the first passband resonant element is inner, and two I/O feeder lines are connected on the short-circuited transmission line of the first passband resonant element.
2. dual frequency filter according to claim 1, is characterized in that: described I/O feeder line adopts tap structure.
3. dual frequency filter according to claim 1, is characterized in that: the characteristic impedance of described I/O feeder line is 50 ohm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310751861.9A CN103762404B (en) | 2013-12-31 | 2013-12-31 | Double-frequency-band filter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310751861.9A CN103762404B (en) | 2013-12-31 | 2013-12-31 | Double-frequency-band filter |
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| Publication Number | Publication Date |
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| CN103762404A CN103762404A (en) | 2014-04-30 |
| CN103762404B true CN103762404B (en) | 2015-07-15 |
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| CN201310751861.9A Expired - Fee Related CN103762404B (en) | 2013-12-31 | 2013-12-31 | Double-frequency-band filter |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104051828A (en) * | 2014-06-24 | 2014-09-17 | 中国科学院微电子研究所 | Minitype band-pass filter with multiple transmission zero points |
| CN104241750B (en) * | 2014-09-16 | 2017-08-29 | 电子科技大学 | A kind of double frequency band-pass filter based on defect microstrip line |
| CN106549199A (en) * | 2016-06-04 | 2017-03-29 | 南京理工大学 | Miniaturisation high-performance microstrip wave filter based on right-hand man's structure |
| CN106450610A (en) * | 2016-11-10 | 2017-02-22 | 电子科技大学 | A novel dual-passband filter |
| CN107565201B (en) * | 2017-09-13 | 2019-10-18 | 电子科技大学 | A kind of microwave oscillator with low phase noise |
| CN108232381A (en) * | 2017-12-13 | 2018-06-29 | 南京熊猫电子股份有限公司 | Multi-zero minimizes inserted double-passband filter |
| CN108598637A (en) * | 2018-04-19 | 2018-09-28 | 超视距成都科技有限责任公司 | Based on the four-step filter for intersecting embedded Stepped Impedance resonant element |
Citations (3)
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|---|---|---|---|---|
| CN102569954A (en) * | 2012-01-16 | 2012-07-11 | 电子科技大学 | Ultra-wideband microstrip filter |
| CN103035985A (en) * | 2012-12-15 | 2013-04-10 | 华南理工大学 | Toroidal cavity resonator based ultra wide band (UWB) notch filter |
| CN103035986A (en) * | 2012-12-15 | 2013-04-10 | 华南理工大学 | Ultra wide-band filter based on double minor matters loading harmonic oscillator |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20130038023A (en) * | 2011-10-07 | 2013-04-17 | 한국전자통신연구원 | Ring resonator and filter having the same |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102569954A (en) * | 2012-01-16 | 2012-07-11 | 电子科技大学 | Ultra-wideband microstrip filter |
| CN103035985A (en) * | 2012-12-15 | 2013-04-10 | 华南理工大学 | Toroidal cavity resonator based ultra wide band (UWB) notch filter |
| CN103035986A (en) * | 2012-12-15 | 2013-04-10 | 华南理工大学 | Ultra wide-band filter based on double minor matters loading harmonic oscillator |
Non-Patent Citations (1)
| Title |
|---|
| Compact dual-band bandpass filter with improved stopband characteristics;X.B. Wei 等;《Electronics Letters》;20120607;第48卷(第12期);全文 * |
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| CN103762404A (en) | 2014-04-30 |
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