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    25 April 2017, Volume 37 Issue 2 Previous Issue    Next Issue
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    Surfacecharginganalysisinducedbyelectronbeamimpactdielectric
    WANG Dan, HE Yong-Ning, LI Yun
    2017, 37 (2):  1-10.  doi: 10.16708/j.cnki.1000-758X.2017.0031
    Abstract ( 471 )   PDF (2899KB) ( 528 )   Save
    Forexistingmultipactoroccurredindielectricmicrowavecomponents,moreattentionispaidtomultipactorsourceandsuppressionfromtheaspectofresonanceandemittedelectronyield,whilethestudyaboutinfluenceofsurfacepotentialonmultipactorisrarelyreported.Secondaryelectronemissioncharacteristicswereanalyzed.Finalsurfacepotentialandelectronimpactenergywereemphaticallystudiedwhenelectronbeamwithconstantenergysostenutoimpactedthedielectricsurfacewithvariousinitialsurfacepotential.Surfacepotentialandelectronimpactenergywerecalculatedwhenthesystembecamestable.Calculateddataindicatesthatsteadystateofthesystemisremarkablyinfluencedbyprimaryenergyandthesecondcriticalenergy.Theinfluenceofsurfacepotentialonsecondaryelectronemissionwassystematicallystudiedwhenelectronswithsingleandcontinuousenergyimpactedthedielectricsurface.An-energyshiftingofcriticalenergyisrevealedwhensurfacepotentialisφ.Forelectronbeamwithcontinuousincidentenergy,impactenergyrangeisdramaticllyeffectedbysurfacepotentialofthedielectric,andtheriskofmultipactorisfurtherinfluenced.
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    Preliminarystudiesofelectronbeambombardmentinstrongelectromagneticfieldbreakdown
    Wu-Cheng, SUN Jun, CHEN Chang-Hua, HUO Shao-Fei, ZHANG Yu-Chuan, CAO Yi-Bing, XIE Jia-Ling
    2017, 37 (2):  11-16.  doi: 10.16708/j.cnki.1000-758X.2017.0027
    Abstract ( 481 )   PDF (3831KB) ( 444 )   Save
    Presently, structureoptimizationandtechnologicaltreatmentaretwomainwaystodepressthestrongelectromagn eticfieldbreakdown.Theenergydepositionabout1MeVelectronsinmetalmaterialswasinvestigatedby BetheenergylosslawandMonteCarlosimulation.Theresultsindicatethattheelectronsinthe materialofsmalleratomicnumberanddensityhavemuchlongereffectiverangeandlowerenergydepo sitiondensity.Thereby, thematerialismoreresistanttoelectronsbombardmentandthebreakdownriskcanbeeffectivelyre duced.Withthesameincidentelectronenergy,thecopper, stainlesssteelandtitaniumwereexperimentallycompared.Owingtoitshighdensity, thecopperisdestroyedmosteasily.Simultaneously,thetitaniumshowsgoodperformanceforitslow density.Thefurtherhighpowermicrowave(HPM)experimentsshowthat,with~2.8GWoutput, theoutputmicrowavepulsewidthoftheRBWOcanbeincreasedto27nsfrom18nswhenthestain lesssteelissubstitutedbythetitaniumandthepulseshorteningiseffectivelydepressed.
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    Analyticalmodelforsecondaryelectronyieldofmetals
    HE Jun, LI Jun, CAO Meng, CUI Wan-Zhao, LIU Chun-Liang
    2017, 37 (2):  12-23.  doi: 10.16708/j.cnki.1000-758X.2017.0023
    Abstract ( 480 )   PDF (1352KB) ( 483 )   Save
    Anaccuratemodelforsecondaryelectronyield(SEY)isofgreatimportanceforthecalculationofmultipactorthreshold,buttheexistingSEYmodelis deficientinsatisfyingtheneedsofaccuracyandconcisenessatthesametime.AnanalyticalmodelforSEYofmetalswaspresentedbyanalyzingtheescapingprobabilityofsecondaryelectronscombinedwiththemodifiedBetheenergylossequation.Furthermore,SEYmodelsforuncleanedandArion cleanedAgsampleswereobtainedbyfittingtheexperimentalresultswiththeanalyticalmodel.CalculationresultsshowthatthestandarddeviationbetweenSEYmodelsandexperimentalresultsofuncleanedandArioncleanedAgiswithin4%atdifferentincidentangles,whichindicatesthattheanalyticalmodelpresentedcanbeusedtoestablishtheaccurateSEYmodelofmetalsandcalculatemultipactorthresholdofspacehighpowermicrowavecomponentanddensityofelectroncloudinaccelerator.
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    Transientcharacteristicsofsecondaryelectronyieldbasedonchargingbalancemode
    FENG Guo-Bao, LI Jun, CUI Wan-Zhao, LIU Chun-Liang, CAO Meng
    2017, 37 (2):  24-31.  doi: 10.16708/j.cnki.1000-758X.2017.0030
    Abstract ( 464 )   PDF (7304KB) ( 193 )   Save
    Theessentialrelationshipbetweensecondaryelectronsemissionand chargingstatesofdielectricwasinvestigatedbasedonchargingbalancemodewithnumericalsimulat ion.BothMonteCarloandfinitedifferencetimedomainalgorithmswereadoptedfornumericalsimulat ion, consideringelasticandinelasticessentialbetweenincidentelectronsandmaterialatomsduringscatte ringprocessandcalculatingdiffusion, driftandtrapeffectsofinternalcharges.Underdifferentchargingbalancemodes, thesecondaryelectronemissionandchargingstatesofdielectricontransientchange, internaldistributionsandsaturationvalueswereanalyzedandsimulated.Theresultsshowthatchargi ngbalancemodescanbedividedintothesecondaryelectron(SE)mode,theleakageelectron(LE) modeandthecombined(CO)mode.TheSEmodecorrespondstothesurfacechargingstate,whiletheLE modecorrespondstothedeepchargingstate.WhenthechargingbalancemodechangestowardsSEmod efromLEmode,boththesecondaryelectronyieldandthenegativesurfacepotentialincreases,while variationtrendsofthetotalchargingquantityandchargingtimeconstantpresenttobeopposite asaresultofbalancemodechange.
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    Amodifiedmodelfortheemissionofsecondaryelectronsbylowenergyelectronimpact
    PENG Kai, LI Jing, ZHANG Ying-Jun, SU Chen, CUI Wan-Zhao
    2017, 37 (2):  32-38.  doi: 10.16708/j.cnki.1000-758X.2017.0039
    Abstract ( 518 )   PDF (2642KB) ( 441 )   Save
    Withthefurtherofstudyofthemultipactor,effectsoflowenergyelectronshadbecomemoreand moreimportant.Inordertosimulateandanalyzemultipactortheoryaccurately,onthebasisofresear chforsecondaryandbackscatteredelectronemissionmodel,anewmodelwasputforwardbased onsecondaryelectronyield(SEY),backscatteredelectronyield(BEY) andtheangleofelectronincidence.ConsideringthedifferenceofSEY,BEYoflowenergyelectron,a ndcompactingseveralsecondaryand backscatteredelectronyieldformulae,thenewmodelformultipact orhadabetterprecisionandapplicability.Finally,somediscussionandanalysiswasdoneforimprovingthecorrectnessandbroadeningthe applicationofthemodel.
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    Dynamiccharacteristicsofsecondaryelectronemissionofdielectricmaterials
    ZHANG Xiu-Sheng, CAO Meng, WENG Ming, WANG Fang
    2017, 37 (2):  39-47.  doi: 10.16708/j.cnki.1000-758X.2017.0038
    Abstract ( 458 )   PDF (7703KB) ( 432 )   Save
    Theresearchondynamiccharacteristicsofdielectricmaterialsis animportantpartinthefieldofsecondaryelectronemission.Bynumericalsimulationmethod,amod eloftheeffectivesecondaryelectroncollectionefficiencywasestablished andtheeffectsofmeasuringparametersonthedynamiccharacteristicswerestudied.Theresultsshow thatspaceelectricfieldandcollectorstructurehassomecorrelationontheeffectivesecondarye lectroncollectorefficiency.Theincreaseofcollectorpotentialcanimprovetheeffectivesecondary electroncollectionefficiencyandthehalfwidthtimeofthedynamicprocesswillincreaselinearly. Inaddition,thecollectorstructurecanaffectthespaceelectricfield.Bydirectlyinfluencingthe collectionefficiency,spaceelectricfieldandcollectorstructureindirectlychangethesurfacecha rgetocausethechangeofdynamiccharacteristics.Theincidentbeamcandirectlyaffectthesurfac echargeaccumulationandmakesthehalfwidthtimeincrease ordecrease.Theresultshaveimportantscientificsignificanceforrevealingthedynamicprocessofch argedmaterialandpredictingtheexperimentthataccuratelymeasuringthesecondaryelectronemission coefficients.
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    Secondaryelectronemissionpropertiesfromborondopeddiamondfilms
    LI Li-Li, DING Ming-Qing, GAO Yu-Juan, SHAO Wen-Sheng, FENG Jin-Jun
    2017, 37 (2):  48-53.  doi: 10.16708/j.cnki.1000-758X.2017.0032
    Abstract ( 558 )   PDF (3852KB) ( 444 )   Save
    Thecathodematerialsusedinelectronmultiplier,fieldemission cathodeandparticle/photondetectorhavetheproblemoflowsecondaryelectronemissionyieldand unstableemission.Tosolvethisproblem, differentboronconcentrationdiamondfilmsbymicrowaveplasmachemicalvapordepositionwereprepared .ThesurfaceofB-dopeddiamondfilmwastreatedbyHydrogenplasma.Thesecondaryelectronemissi on(SEE)fromB-dopeddiamondfilmswasinvestigated. Thescanningelectronmicroscopy(SEM)andtheRamanspectrumanalysiswereusedtoexaminethepropertiesoftheB-dopeddiamondfilm. ThemaximumSEEyieldupto18.3at1keVprimarybeamenergywasfoundundertheconditionthatthesampleswereleftinairforweeksandsubjecttonotreatmentpriortothemeasurement.Oxidationtreatmentdestroysnegativeelectronaffinity(NEA)whereasheatingupinvacuumsubstantiallybringsbackNEA.B-dopeddiamondfilmisexpectedtobeusedinelectronmultiplier,fieldemissioncathodeandparticle/photondetector.
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    TechniqueforinhibitingsecondaryelectronemissionofsilverbasedonZnOarray
    HU Tian-Cun, CAO Meng, BAO Yan, ZHANG Yong-Hui, MA Jian-Zhong, CUI Wan-Zhao
    2017, 37 (2):  54-60.  doi: 10.16708/j.cnki.1000-758X.2017.0034
    Abstract ( 629 )   PDF (13052KB) ( 215 )   Save
    WithsatellitepayloadRFpowerincreasing,traditionalmethodsof inhibitingmultipactorareunabletomeettheneedsofhighpowersatellitepayloads.Reducingthe secondaryelectronemissioncoefficientofinternalsurfaceofhighpowerRFcomponentsisanimpor tantmethodforinhibitingmutipactor.Nanoscalesilvertrappingstructurewaspreparedbyconstructing nanodimensionZnOarrays,  andtheeffectsofpreparingmethodsofseedsandzincsaltconcentration onthegrowthofZnOarrayswerestudied.TheresultsshowthathomogeneousZnOarraysareobtain edonthesamplesurfacebyusingtheUVradiationforseedssynthesizationandincreasingzincsaltconcentration.TheeffectofpackingdensityofZnOarraysonsilverfilmsconstructionwasinvest igated.ItshowsthatlowdensityZnOarraysaresuitablefordepositionofsilveronthesurface ofZnOnanorods.Therefore,  thetechnologyforpreparationoftrapstructuresilverbasedonZnOarray swasobtained,andthemaximumsecondaryelectronemissioncoefficientofsilverdecreasedby36.3% .
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    Improvingtheefficiencyofthecollectorofspacetravelingwavetubewithmicromachiningtechnology
    BAI Chun-Jiang, CUI Wan-Zhao, YE Ming, HE Yong-Ning
    2017, 37 (2):  61-65.  doi: 10.16708/j.cnki.1000-758X.2017.0037
    Abstract ( 475 )   PDF (3451KB) ( 415 )   Save
    Thesecondaryelectronyield (SEY) hasgreatinfluenceontheefficiencyofthecollectorofspacetravelingwavetube.Therefore,
    theefficiencyofcollectorwasimprovedbyreducingthesecondaryelectronyieldofthematerial′ssurfaceofcollector. TheOFHCcoppersamplewastreatedwithchemicaletching.Afterchemicaletching,somemicroporous arraystructureswereremainedonthesample.Thenthesecondaryelectronyieldofthesamplewasm easuredbythesecondaryelectronyieldmeasurementplatform.Andtheresultshowsthatcomparingwiththeoriginalsamplewhichisnottreated,themaximumofSEYdecreasesfrom1.33to0.96.And theSEYissuppressedwell.ThentheSEYcurvesobtainedfromSEYmeasurementplatformwereused  inthedesign ofSTWTcollector.TostudytheinfluenceoftheSEY,threecollectormodelswereusedtocalculate theefficiencyofthemodelswithsimulationsoftware.Itisverifiedthattheefficiencyofthe threecollectorsareimprovedfrom80.1%,57.5%,42.1%to82.55%,62.6%,59.2%,respectively.ThemethoddiscussedwillbehelpfulfortheSTWTdesign.
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    Equivalentpowerdeterminationforsingleeventmulticarriermultipactorbasedona modifieddifferentialevolutionalgorithm
    WANG Xin-Bo, ZHANG Xiao-Ning, LI Yong-Dong, LIU Chun-Liang, WANG Rui, WEI Huan, RAN Li-Xin
    2017, 37 (2):  66-72.  doi: 10.16708/j.cnki.1000-758X.2017.0033
    Abstract ( 509 )   PDF (3302KB) ( 488 )   Save
    Multipactorisoneofthemostimportantfailure   effectsforthespacebornemicrowavecomponents.Withtherapiddevelopmentofwidebandcommunication satellitesystems,themulticarriermultipactor(MM) ispaidmoreandmoreattentions.Whilethedesigncriterionwithmicrowavecomponentsforsingle carrierRFsignalisexplicit,itiscontroversialformulticarriermultipactor.Amethodtodetermine equivalentpowerforthesingleeventmulticarriermultipactorusingthemodifieddifferentialevol utionalgorithmwaspresentedtoovercomethedisadvantagesoftheconventionalempiricalformula.The powerpropertiesforthemulticarriersynthesissignalswereanalyzed,andtheenergyin20electrontransittimewasgloballyoptimized.Ineachoptimization,quadratic  interpolationwasusedtofind thelocaloptimum,thentheglobaloptimumwasobtainedbyusingthemodifiedDifferentialEvolutio nalgorithm.Itistheworstcaseforallkindsofconfigurationsandtheoptimalaveragepowercanbeusedfortheequivalentpowerinthewidebandcomponentdesign.Theproposedmethodisdemonst ratedwiththeuniformamplitudeandequallyspacedfrequencies.Theproposedapproachisalsoable toprovidereasonableequivalentpowerformulticarriersignalswithnonuniformamplitudesorthe unequallyspacedfrequencies.
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    Anovelsimulationmethodofmultipactorincomplexcomponentforsatelliteapplication
    LI Yun, CUI Wan-Zhao, ZHANG Hong-Tai, YIN Xin-She, WANG Hong-Guang, ZHANG Jian-Feng, HE Yong-Ning
    2017, 37 (2):  73-80.  doi: 10.16708/j.cnki.1000-758X.2017.0040
    Abstract ( 502 )   PDF (3025KB) ( 507 )   Save
    Withthedevelopmentofhighpowerandminiaturizationinsatellitepayload,accuratesimulationandthresholdanalysisformultipactorin   complexcomponentbecomesbottleneckproblem.Basedontheparticleincelltechnologyandthesecondaryelectronemissiontheory,athreedimensionalsimulationmethodformultipactorwaspresented.Thenumericalalgorithmwasselfconsistentsincetheinteractionbetweenelectromagneticfieldsandparticleswasproperlymodeled.Thegenerationofmultipactoris   visualized,  sothat adeepinsightintothephysicalmechanismsofthiseffectwasgained.Inordertovalidatethemethod,multipactionintheimpedancetransformerwasstudied.Byanalyzingtheevolutionoftheelectronnumbersobtainedbyourmethod,multipactorthresholdsofthesecomponentswereestimatedandthemostsensitivepositionswheremultipactoroccurswerevisualized.Theresultsshowgoodagreementwiththeexperimentalresultsandthesimulationerrorislessthan1.2dB.
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    econdaryelectronsaccumulationinspacemicrowavecomponentsanditsrelationshipwithtransmissionproperties
    ZHANG Heng, CUI Wan-Zhao, LI Yun, WANG Xin-Bo, YANG Jing
    2017, 37 (2):  81-88.  doi: 10.16708/j.cnki.1000-758X.2017.0024
    Abstract ( 410 )   PDF (5414KB) ( 405 )   Save
    Therelationshipbetweentheaccumulationofmultipactingelectronsandthevariationofthetransmissionpropertiesinmicrowavecomponentswasstudied.  Anequivalentmediamodelwasproposedtodescribetheelectronaccumulationduringmultipactor,whereeffectsoftheelectrons′accumulationwereapproximatedasamediawithspecialrelativepermittivity.Thevalueofthespecialrelativepermittivitywascalculatedequivalentlycorrespondingtotheelectrondensity.Simulationandcalculationresultsindicatethatthetransmissionpropertiesofthemicrowavecomponentsremainunchangedwhenthedensityofelectronsincreasedfrom0/m3to1×1016/m3duringmultipactor.However,thereturnlossinthepassbandfrequenciesdropped15dBwhentheelectrondensityreached1×1017/m3.Astheincreasingoftheelectrondensity,thereflectionofelectromagneticwavecausedby“equivalent  media”increasedrapidlywhichmadethetransmissionpropertiesofthemicrowavecomponentsdeterioratessharply.Thesimulationwascoincidewiththeresultsoftheoreticalanalysis,whichindicatedthatthetransmissionwasevencutoffwhenthedensityofelectronsincreasedtothemagnitudeof4×1017/m3.Inaddition,whentheelectrondensityreached4×1017/m3(inthefrequencyrangeof2.5~5GHz),therelativepermittivityofthe“equivalentmedia”wasnegativeandthetransmissioncutoff.Thisresearchishelpfultounderstandthemechanismandtheelectricalcharacteristicschangesofmicrowavecomponentsduetomultipactor,providinganeffectivetheoreticalprincipleformultipactorsuppression.
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    Multipactorsimulationalgorithmbasedonfinitedifferenceintimedomain
    ZHANG Jian-Feng, YOU Jian-Wei, WANG Hong-Guang, LI Yun, CUI Wan-Zhao, CUI Tie-Jun
    2017, 37 (2):  89-95.  doi: 10.16708/j.cnki.1000-758X.2017.0036
    Abstract ( 520 )   PDF (5722KB) ( 956 )   Save
    Traditionalmultipactorpredictionmethodbasedonplaneapproximationisfastbutinaccurate,whichcannotmeettheelectricalperformancedesignrequirementswhendevicesbecomemoreandmorecomplex.Thefinitedifferencetimedomainalgorithmisoneofthemostpopularmethodsinthecomputationalelectromagnetics.TheparticletracingalgorithmisanumericalmethodbasedontheNewton'sforcelaw. Thetwoalgorithmscanbeselfconsistentlycombinedbythediscretemeshinbothtimeandspacedomains,whichcanbeusedtopredictthemultipactorbreakdownthreshold.Inaddition,theconformalandparallelizingtechnologieswerewellstudied.Multipactorbreakdownofclassicmicrowavedevicewasanalyzedbythedevelopedalgorithm.Theerroris0.3dBcomparedwiththeexperimentsandthemaximumparallelefficiencyis83%,whichdemonstratetheaccuracyandefficiencyofthealgorithm.
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    ExperimentalresearchonanSbandinjectlockingmagnetronformultipactordischargetest
    CHEN Xiao-Jie, LIU Zhen-Long, LIU Chang-Jun
    2017, 37 (2):  96-102.  doi: 10.16708/j.cnki.1000-758X.2017.0025
    Abstract ( 486 )   PDF (7779KB) ( 211 )   Save
    S-bandinject-lockingmagnetronexperimentforthegroundmultipactordischargetestwasproposedforthelargepowermicrowavesourceofsatellite.Thedirectlyproportionalrelationbetweenthemagnetroninject-lockingbandwidthandtheinjectionratiowasstudiedbasedontheinject-lockingcontinuouswavemagnetrontheory.Themagnetronoutputpowervariedfrom389Wto1150Wbytuningthemagnetronanodecurrent.TheinjectionlockingbandwidthatSbandofthe1kWcontinuouswavemagnetronwasbroadenedto12.6MHzbyincreasingtheinjectedpower.Dual-frequencyinject-locking,spurioussuppressionandpowerdistributionwereobservedinthetwo-toneinjectionexperiments.
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    Studyonlife-testofM-typeimpregnatedcathodeforspaceTWT
    SHAO Wen-Sheng, LI Ji, YU Zhi-Qiang, CHENG Cheng, ZHANG Ke, WANG Hui, WANG Li-Shan
    2017, 37 (2):  103-107.  doi: 10.16708/j.cnki.1000-758X.2017.0035
    Abstract ( 656 )   PDF (6596KB) ( 412 )   Save
    Spacetravellingwavetube(STWT)withlonglifeplaysanimportantroleonthepoweramplifierforsatellitecommunicationsystem.ThelifeoftheSTWTismainlyrestrictedbythecathodelife.InordertoensurethattheSTWTcanhavealonginorbitoperatingtime,itisnecessarytocarryoutplentyexperimentalresearchesonthelifeofSTWTcathode,andtopredictthelifeoftheSTWTcathode.Theaccumulatinglifetesttimeis1823080hoursfor50electronguns,thelongestlifetesttimeisover65411hours.Thelifepredictionmodelwasbuiltonthebasisofthechangeoftheworkfunctionduringthelifetime.Thepredictinglifeismorethan43yearswhenthecathodeisdrawnacurrentdensityof1A/cm2at960℃b (℃b: brightnesstemperature),itismorethan22yearsat980℃b,  anditismorethan15yearsat1000℃b.ThepredictinglifeshowsthatthelonglifeSTWTcathodecanmeettherequirementsofthesatellitecommunicationsystem.
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    StudyoncommunicationperformanceimprovementusingLDPCcodeunderpassiveintermodulationinterference
    FANG Tian-Qi, HU Tian-Cun, TIAN Lu, LIU Jian-Chun
    2017, 37 (2):  108-113.  doi: 10.16708/j.cnki.1000-758X.2017.0029
    Abstract ( 418 )   PDF (3886KB) ( 526 )   Save
    Duetothetimevaryinganddiscontinuouscharacteristicsofpassiveintermodulationinterferencesignals,anovelmethodbyusingerrorcorrectingLDPCcodewasproposedtoreducetheimpactofpassiveintermodulationinterference.TheLDPCcodinganddecodingschemewasdesignedandthedecodingpartwasemphasized.Thenormalizedminsumalgorithmbasedonrowmessagepassingwasadoptedforitslowiterationtime.Pulsesat10%dutycyclewereusedtosimulatethepassiveintermodulationinterference.Thesimulationresultsshowthatthecodinggainisabout8.2dBwhentheBERis3.1dB. TheexperimentalresultsshowthattheBERis0.00269andSIRgainreaches10dBwhenSIRis2dB.
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