CN104733827A - High isolation microstrip branch line orientate coupler with short circuit section - Google Patents
High isolation microstrip branch line orientate coupler with short circuit section Download PDFInfo
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- CN104733827A CN104733827A CN201510176767.4A CN201510176767A CN104733827A CN 104733827 A CN104733827 A CN 104733827A CN 201510176767 A CN201510176767 A CN 201510176767A CN 104733827 A CN104733827 A CN 104733827A
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Abstract
Disclosed is a high isolation microstrip branch line orientate coupler with a short circuit section. On the basis of a standard microstrip branch line orientate coupler, a terminal short circuit microstrip line is arranged at a coupling terminal of the orientate coupler additionally; one end of the short circuit microstrip line is connected to a microstrip line of the coupling terminal, and the other end is in short circuit. By utilizing the power of the short circuit microstrip line reflected to an isolation terminal, the power leaked from an incident terminal is neutralized, the isolation degree of the orientate coupler is raised, the output of the coupling terminal and direct terminal are not affected by the short circuit microstrip line, but the isolation degree between an input terminal and the isolation terminal can be raised effectively in the certain bandwidth range. The orientate coupler has the advantages that structure is simple, machining is facilitated, and cost increase is avoided.
Description
Technical field
The invention belongs to microwave technical field, relate to directional coupler, be applied to various radio-frequency recognition system and wireless communication system, for a kind of with the high-isolation microstrip branch line directional coupler of short branch.
Background technology
Directional coupler is one widely used passive device in microwave and radio circuit, and the quality of its index directly affects the performance of whole system.The technical indicator of directional coupler mainly contains the degree of coupling, isolation, amplitude balance, phase balance and bandwidth of operation etc., isolation between two isolated ports of the wherein directional coupler of microstrip branch line structure is generally at 20-25dB, and in the frequency band range being greater than 1% bandwidth, isolation being brought up to more than 30dB as needed then needs to take special technical measures.
Summary of the invention
The object of the invention is to the problem for how improving directional coupler isolation, proposing a kind of microstrip branch line directional coupler with short circuit branch line,
Technical scheme of the present invention is: the high-isolation microstrip branch line directional coupler of band short branch, in the coupling port of micro-band two branch line directional coupler, a short-circuit micro-band line is set, short-circuit micro-band line is arranged on distance coupling port 1/8 wavelength place, length is 1/4 wavelength, described wavelength refers to the wavelength at directional coupler center frequency points place, the microstrip line of short-circuit micro-band line one end butt coupling port, other end short circuit.
As optimal way, the short-circuit structure of short-circuit micro-band line is: adopt metal wire directly to connect short-circuit micro-band line and metal base plate in the edge of directional coupler circuit board.
As another kind of optimal way, the short-circuit structure of short-circuit micro-band line is: adopt via structure to connect the metal base plate of short-circuit micro-band line and directional coupler circuit board.
The characteristic impedance of short-circuit micro-band line is 75 Ω ~ 100 Ω.
The present invention is based on standard microstrip two branch line directional coupler, by increasing a short circuit branch line in coupling port, i.e. short-circuit micro-band line, short-circuit micro-band line reflection is utilized to return the power of isolated port, make it to leak with entry port the power of coming to be formed and offset, thus improve the isolation of directional coupler.
The present invention proposes a kind of design for microstrip branch line structure directional coupler, the short-circuit micro-band line arranged does not affect the output of coupling port and straight-through port, and effectively the isolation between input port and isolated port can be brought up to more than 30dB in the frequency band range that band is wider than 1% simultaneously.It is simple, easy to process that this design has structure, and substantially do not increase the advantage of cost.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention
Fig. 2 is the plane graph of circuit of the present invention.
Fig. 3 measures the centre frequency that obtains when being 915MHz, the reflection coefficient of directional coupler and the frequency characteristic of isolation, also namely uses vector network analyzer to measure return loss S in the S parameter of acquisition
11, isolation S
41.
Embodiment
The present invention devises a kind of high-isolation microstrip branch line directional coupler with short branch, adopt standard microstrip branch line directional coupling structure, the microstrip line of a terminal short circuit is added in the coupling port of directional coupler, position is at distance wavelength place, port one/8, the length of this short-circuit line is quarter-wave, with the wavelength at directional coupler center frequency points place for basis, as shown in fig. 1, short circuit manner has two kinds, metal wire can be adopted directly to connect microstrip line and metal base plate in the edge of circuit board, if the edge not at circuit board then can adopt via structure to connect microstrip line and metal base plate, two kinds of connected modes bring impact can not to the performance of directional coupler.What Fig. 1 provided is the high-isolation directional coupler be made up of short branch and standard microstrip branch line directional coupler.
Fig. 1 is structural representation of the present invention, and Fig. 2 is the circuit planes figure of corresponding diagram 1, shows directional coupler input port microstrip line 1, and isolated port exports microstrip line 4, and straight-through port exports microstrip line 2, and coupling port exports microstrip line 3; Four section of 1/4 wave microstrip line 5,6,7,8 forms two branch 3dB directional couplers of standard; The short-circuit micro-band line 9 that coupling port is added; Label 10 represents the distance segment between short-circuit micro-band line and coupled end output port, and metal wire 11 connects the microstrip line on upper strata and the metal bottom surface of bottom, for realizing short circuit; Label 12 represents medium substrate, and 13 is metal base plates, does not show in accompanying drawing.
Advantage of the present invention: structure is simple, be easy to make, superior performance.Below by embodiment, enforcement of the present invention is described.
Embodiment: medium substrate 12 selects that relative dielectric constant is 2.2, thickness is 1.0 millimeters, length got by short-circuit micro-band line 9 is 62.0 millimeters, width is 0.8 millimeter, characteristic impedance is 75 Ω ~ 100 Ω, metal wire 11 length is 1 millimeter, width is 0.8 millimeter, and the characteristic impedance of input and output microstrip line 1,2,3,4 is 50 Ω, and 1/4 wave microstrip line segment 5,6,7,8 is by the design of standard two branch 3dB directional coupler.
Contrast Fig. 3, which gives the parameter curve of the directional coupler of embodiment.This directional coupler has good isolation in centre frequency as seen from the figure, owing to have employed short-circuit micro-band line, and isolation S
41can keep the isolation of more than-40dB in the bandwidth range of 10.4MHz, and the reflection coefficient of input port remains on more than-35dB.Result shows, directional coupler function admirable of the present invention, and structure is simply convenient to processing, is with a wide range of applications.
Claims (3)
1. be with the high-isolation microstrip branch line directional coupler of short branch, it is characterized in that arranging a short-circuit micro-band line in the coupling port of micro-band two branch directional coupler, short-circuit micro-band line is arranged on distance coupling port 1/8 wavelength place, length is 1/4 wavelength, described wavelength refers to the wavelength at directional coupler center frequency points place, the microstrip line of short-circuit micro-band line one end butt coupling port, other end short circuit.
2. microstrip branch line directional coupler according to claim 1, it is characterized in that the short-circuit structure of short-circuit micro-band line is: adopt metal wire directly to connect microstrip line and metal base plate realizes short circuit in the edge of directional coupler circuit board, if then do not adopted the metal base plate of metal via structures connection microstrip line and directional coupler circuit board to realize short circuit in edge.
3. microstrip branch line directional coupler according to claim 1 and 2, is characterized in that the characteristic impedance of short-circuit micro-band line is 75 Ω ~ 100 Ω.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510176767.4A CN104733827A (en) | 2015-04-14 | 2015-04-14 | High isolation microstrip branch line orientate coupler with short circuit section |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510176767.4A CN104733827A (en) | 2015-04-14 | 2015-04-14 | High isolation microstrip branch line orientate coupler with short circuit section |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104733827A true CN104733827A (en) | 2015-06-24 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510176767.4A Pending CN104733827A (en) | 2015-04-14 | 2015-04-14 | High isolation microstrip branch line orientate coupler with short circuit section |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105870566A (en) * | 2016-05-09 | 2016-08-17 | 大连海事大学 | Terminating complex impedance branch line directional coupler |
| CN109357728A (en) * | 2018-10-19 | 2019-02-19 | 北京古大仪表有限公司 | A kind of double branch directional couplers of micro-strip and radar level gauging system |
| CN112310584A (en) * | 2020-10-30 | 2021-02-02 | 广东鸿展通信技术有限公司 | Ring filter |
| CN112909473A (en) * | 2021-02-09 | 2021-06-04 | 江苏势通生物科技有限公司 | Improved annular directional coupler circuit |
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| US4127831A (en) * | 1977-02-07 | 1978-11-28 | Riblet Gordon P | Branch line directional coupler having an impedance matching network connected to a port |
| GB2152292A (en) * | 1983-12-21 | 1985-07-31 | Mitsubishi Electric Corp | Directional coupler |
| CN1183172A (en) * | 1996-03-22 | 1998-05-27 | 松下电器产业株式会社 | Low-pass. filter with directional coupler and potable telephone set using the same |
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| CN103311630A (en) * | 2012-12-29 | 2013-09-18 | 南京理工大学 | C-waveband ultra-wideband multi-octave miniature directional coupler |
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| US4127831A (en) * | 1977-02-07 | 1978-11-28 | Riblet Gordon P | Branch line directional coupler having an impedance matching network connected to a port |
| GB2152292A (en) * | 1983-12-21 | 1985-07-31 | Mitsubishi Electric Corp | Directional coupler |
| CN1183172A (en) * | 1996-03-22 | 1998-05-27 | 松下电器产业株式会社 | Low-pass. filter with directional coupler and potable telephone set using the same |
| CN2643581Y (en) * | 2003-08-29 | 2004-09-22 | 西安海天天线科技股份有限公司 | Multiband microwave small-sized mixed bridge |
| CN101102003A (en) * | 2007-07-13 | 2008-01-09 | 东南大学 | Any dual-frequency band 3dB branch directional coupler |
| CN201478429U (en) * | 2009-07-22 | 2010-05-19 | 中兴通讯股份有限公司 | Microstrip line directional coupler |
| JP2012244619A (en) * | 2011-05-19 | 2012-12-10 | Yoshihiro Konishi | Microwave circuit using distributed constant line having vertical planar structure |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105870566A (en) * | 2016-05-09 | 2016-08-17 | 大连海事大学 | Terminating complex impedance branch line directional coupler |
| CN109357728A (en) * | 2018-10-19 | 2019-02-19 | 北京古大仪表有限公司 | A kind of double branch directional couplers of micro-strip and radar level gauging system |
| CN113483856A (en) * | 2018-10-19 | 2021-10-08 | 北京古大仪表有限公司 | Microstrip double-branch directional coupler and radar level measurement system |
| CN112310584A (en) * | 2020-10-30 | 2021-02-02 | 广东鸿展通信技术有限公司 | Ring filter |
| CN112310584B (en) * | 2020-10-30 | 2021-11-05 | 广东鸿展通信技术有限公司 | Ring filter |
| CN112909473A (en) * | 2021-02-09 | 2021-06-04 | 江苏势通生物科技有限公司 | Improved annular directional coupler circuit |
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Application publication date: 20150624 |