Microstrip line corner is microstrip line one of discontinuous structures, the craft standard of company of certain even and large communication uses the engineer that a few have experience so called experience tells you: Use “3W regular ” undertakes microstrip line corner, in order to reduce discontinuous brought reflex. However, can have everybody ever asked in reply is “3W regular ” true? Why be 3W?
The article undertook be emulationed in detail in the light of microstrip line corner, card palpability is wide for the “3W regulation that circulate ” is not the processing way with optimal function. In the meantime, we are optimized through emulating, offerred other program to be used in order to offer the circumstance reference with function index high demand.
What is microstrip discontinuous?
Microstrip line serves as a kind of the commonnest planar transmission line, go up oneself wide already application is in the century since 60 time in radio frequency circuit. Graph 1 showed sketch map of microstrip route structure. Among them W indicates microstrip line breadth, t expresses microstrip line ply, h states microstrip line arrives the referenced medium ply between, εRExpress the dielectric constant of medium.
Graph sketch map of structure of 1 microstrip route
When actual circuit wiring, because presswork board the limitation of size, often need to do a turn to fold line processing, can appear in PCB namely microstrip line corner, the microstrip line that it attributes a model is discontinuous one of structures. Document  gave out the equivalent model that microstrip line right angle discounts a turn, if the graph is shown 2 times, detailed equivalent derivation consults please document  . Because microstrip circuit dimension and working wavelengh can are likened to, so this kind of discontinuous sex can introduce parasitism reactance, cause thereby phasic with amplitude error, input and output break match, and the parasitism that exists possiblyCoupling, bring about the aggravation of circuit function then, the transmission that affects PCB circuit signal is characteristic.
Graph right angle of 2 microstrip line discounts curved sketch map and equivalent model
With 2.4G frequency paragraph for exemple, low cost designs middling to use common FR4 board, stick install 0402 enclosed capacitance or inductance to undertake impedance matchs, line of the microstrip in be being used actually to reduce and yuan what parts of an apparatus solders is discontinuous, microstrip line line is broad be close to 0.5mm as far as possible (0402 enclose width) . The impedance of character of TXline software computation of use AWR company is the structural parameter of 50Ω transmission line, it is initiative value according to this, software of reuse Ansoft HFSS is emulated to undertaking point-blank, search a reflex most the structural parameter of the hour, final computation parameter is:
T=0.035mm (1oz copper is thick)
Emulation result is shown 3 times like the graph, when W=0.484mm, reflex coefficient S11=-43.26dB, two curves in the graph state academic line is broad respectively S11 of coefficient of as wide as the line after optimizing reflex, top left corner tagged 2.4G frequency paragraph reflection coefficient reading, top right corner showed HFSS emulates a model. Calculate at theory relatively result W=0.5mm, emulation result shows classics HFSS is emulated after optimizing, s11 was reduced make an appointment with 13dB.
Graph 3 microstrip line emulates a result point-blank
Use above parameter undertook emulation to folding a turn squarely, emulation result is shown 4 times like the graph, see apparently, microstrip line right angle folded a turn to increase to make an appointment with 14dB than linear reflex, achieved – 29.82dB.
Note: Grow an influence to eliminate a line, the article is all in emulation model, microstrip line total length is equal (50mm) .
Graph 4 right angle break curved emulation result
The “3W regular ” that you want
To reduce microstrip line reflex, may a lot of engineers tell you: Follow 3W regulation.
What is 3W regulation? The circular arc that 3W regulation expresses to use radius is more than wide W of 3 times line has turn, can make turning line broad change minor, reduce discontinuous sex thereby, sweep for “ in what say on microstrip line sweep past bend ” , if pursue,5 are shown.
Graph 5 sweep sweep past bend sketch map
Undertake to this structure electromagnetism is emulated, emulation result is shown 6 times like the graph. Should sweep when sweeping past bend radius R=3W, s11=-34.6dB, when R=4W, s11 increases instead, till R=11W when, sweep the S11 ability that sweeps past bend to fall very low, achieve – 40.03dB. Can explain the article opens an one of doubt that raise right now: Why be 3W? Because,be when R=3W, s11 value can have satisfied most use requirement, if increase R again (for instance R=4W) , performance is a bit poor instead, increase very great gift to make function index adjacent till R at linear, but will take up right now very large PCB space, this is in compositive in spending higher and higher PCB position, cannot accept.
Graph 6 sweep sweep past bend to emulate optimize a result
Might as well outside trying right angle to curve 45° inclined cut
Document  was offerred other a few kinds of microstrip are discontinuous sexual compensatory a few kinds of plan, document  ,  ,  is mixed with experimental method numeric method labor the signal of bent of microstrip line right angle of different structure transmits character, the equivalent electric capacity that undertakes to microstrip line processing can reduce corner to be in cutting corner, compensate bent of microstrip line right angle thereby discontinuous sex effect, theoretic applicable of this kind of method the corner at aleatoric Zhang Jiao. Outside pointing out microstrip line right angle curves 45° in document inclined cut configuration to be able to improve signal to transmit character well and existence is optimal inclined cut rate.
Outside curving 45° squarely inclined if the graph is shown 7 times,cut configuration, graph (A) in D states microstrip line right angle bends inside corner comes outside the distance of corner, x expresses 45° outside inclined cut the distance that is in the corner outside coming, outside defining inclined cut rate: M= (X/d) &TiMes;100, the corner outside meaning microstrip line right angle to bend when M=0 is done not have by cut, and the corner outside microstrip line right angle is being meant to bend when M=100 by complete cut, distribute microstrip line into two parts from sinuosity.
Graph 7 right angle curve 45° outside inclined cut sketch map
The article also undertook emulation to this kind of plan, if emulation result pursues 8. When inclined when cutting rate =80, s11=-41.492dB, reflection is the smallest, explain this plan can get the performance with more regular than “3W better ” through optimizing. Comparative literature  ,  , [the experience in 5] is formulary, emulation result is put in certain deviation to it, still need to get optimum behavior through debugging ability actually.
Graph 8 right angle curve 45° outside inclined cut emulate optimize a result
The article leaves piece another doubt that raise right now also be readily solved: Why to choose 3W regulation? Through above emulation analysis and many document show, “ right angle curves 45° outside inclined cut ” law to be able to acquire the property that has actor more, but the effect that needs to emulate union to debug ability actually to reach expectation, the process is opposite relatively multifarious and time-consuming. Not tall to performance demand circumstance, most person can choose “3W regular ” , accelerate project plan. After all, time is money.
Offset with reflection reflection
Microstrip line is discontinuous bring about signal reflection is big, “3W regular ” and “ right angle curve 45° outside inclined cut ” two kinds of plan regard compensation as measure, did not achieve linear performance completely. WeYesThe technical exploration, get to the bottom of to detailCan you hereto only?
Contradiction always has two sides sex, Whether can we use contradictory and quits contradiction, use reflex quits reflex? Then, we from transmission line for many times catoptric viewDotSet out, offer structure of a kind of corner, adopt a bend twice, produce reflection twice, expectation can use reflection quits reflex. The structure is shown 9 times like the graph, this structure and by small make up name for ” of “ double turn, among them Γ1It is the reflection coefficient of turn of the first place, Γ2It is the reflection coefficient of turn of the 2nd place, θ is two place the transmission line between the turn is phasic, for constructive and convenient, replace with length L in emulate, w is a line wide, besides turn place, microstrip line is other everywhere width all is W, the W in be being emulated with above is worth (0.484mm) keep consistent.
Graph sketch map of structure of 9 pairs of turns
Debug through emulating optimize, when L=10mm, s11=-42.6dB, achieve the smallest, be equal almost at linear the function when. More regular than “3W ” rose to make an appointment with 8dB, outside curving 45° than “ right angle inclined cut ” law to rise to make an appointment with 2dB. Emulation result is shown 10 times like the graph, function contrast watch sees a table 1.
Graph 10 pairs of turns are emulated optimize a result
Express contrast of function of plan of turn round of 1 microstrip line
The design case that uses reflection to offset catoptric method undertakes still has a lot of, for example rank jump impedanceFilterWith wave guide flangeDish.
Good, we are summed up finally
Microstrip line is discontinuous in sexual solution, although “3W regular ” is not the program with optimal function, but in applying actually, because its do not need to undertake be emulationed in detail with debug optimize, managing develop time, accordingly, asking to be not particularly strict circumstance to function, still be the most convenient choice. “ right angle curves 45° outside inclined cut ” to be able to get very good performance not only, and space of can managing PCB, below the circumstance that undertake emulation conditionally and debugs actually, recommend use this kind of program. Plan of ” of “ double turn, although can obtain the property that rivals with linear photograph, but because its are emulated,debug difficulty big, and take up space, not be very recommend.
Send far electron wireless communication product
ZLG sends far electron the equipment such as the high-powered spectrum analyzer that product of each wireless communication passed major, vector signal analyzer checks, have an insight into each detail of wireless module signal, assure the consistency of product signal.
 Tsinghua university ” microstrip circuit ” write group. Microstrip circuit [M] . Beijing: ? ? 2017 of brume of heir Ti solid red aing concubine of an emperor: 103-104.
David M.Pozar. Microwave project (the 3rd edition) [M] . Beijing: ? ?2014 of brume of party of Qian commonplace ひ aing concubine of an emperor: 64-65, 357-358, 100.
 SilvesTeR P, benedek P. Microst Rip Discontinuity Capacitances For Right2Angle Bends, t Junction, and Crossings [J] .IEEE Trans On Microwave Theory And Techniques, 1973, 21(5):3412346.
 Douvilie R J P, james D S. Experiment Study Of Symmetric Microstrip Bends And Their Compensation [J] . IEEE Trans On Microwave Theory Tech, 1978, 26 (3) : 1752182.
 Lu Hongmin, wu Baoyi, yao Zhicheng, etc. Microstrip line right angle bends optimal inclined cut rate research [J] . Xi’an electron science and technology university journal (science edition) , 2009, 36(5):885-889.
 Wang Kewei, wang Junhong. Microstrip line corner transmits as characteristic as reflection research [J] . Microwave journal, 2006, 22(3) : 33235.
 Liang Changhong, xie Yongjun, guan Bairan. Compendious microwave [M] . Beijing: Higher education press, 2006: 172.
 Chen Peng, cao Muyun. Method of discontinuous sex compensation emulates microstrip line research [J] . Electronic science and technology, 2013, 26(3):119-121.
 Chen Wei, zhao Na, tao Xuemin. HFSS of method of discontinuous sex compensation emulates microstrip line analysis [J] . Contemporary electron technology, 2011, 34(13) : 92-94.
 Mao Jianbo, huang Zhengfeng, yang Mingwu, etc. Discontinuous sex radiate studies microstrip line [J] . The electron is measured with instrument journal, 2012, 26(5):392-397.