提出了一种新的盘荷波导耦合器数值设计方法; 通过分析Kyhl提出的耦合器调节原理, 将输入阻抗之间的相差关系转换为耦合器输入波导的边界条件关系, 由此 利用Microwave Studio的EigenMode Solver求解本征值问题来实现对耦合器 调谐、调匹配过程的模拟; 并给出一个实例来说明数值

30 6 2006 6

HIGH

ENERGY

PHYSICS

AND

NUCLEAR

PHYSICS

Vol.30,No.6

Jun.,2006

ACalculationMethodforRFCouplersDesignBasedon

NumericalSimulationbyMicrowaveStudio*

WANGRong1)

PEIYuan-JiJINKai

(UniversityofScienceandTechnologyofChina,

NationalSynchrotronRadiationLaboratory,Hefei230029,China)

AbstractAnumericalsimulationmethodforcouplerdesignisproposed.Itisbasedonthematching

procedureforthe2π/3structuregivenbyDr.R.L.Kyhl.MicrowaveStudioEigenModeSolverisusedforsuchnumericalsimulation.Thesimulationforacouplerhasbeen nishedwiththismethodandthesimulationdataarecomparedwithexperimentalmeasurements.Theresultsshowthatthisnumericalsimulationmethodisfeasibleforcouplerdesign.

KeywordsRFcoupler,microwavestudio,numericalsimulationcalculation,eigenvalue

1Introduction

ForaLinacacceleratingstructure,theRFcoupler

ratecalculationresultsanditisverytimeconsumingforthenecessarytimedomaincalculationinMAFIA.CSTMicrowaveStudio(MWS),whichisalsobasedontheFiniteIntegrationMethod(FIT),hasaveryfriendlyuserinterfacetocreateallkindsofcom-plicated3Dstructures.WiththehelpofthespecialmeshgenerationpropertiesPBA(PerfectBoundaryApproximation)andTST(ThinSheetTechnology),itwillneedlessmeshcellsforagoodmeshmodelsothatwecangetasamecalculationerrorbycostinglesstimethanthatinMAFIA.

InthispaperanovelnumericalcalculationmethodwiththeMWSEigenmodeSolverispro-posed,whichisbasedontheexperimentalmethodfortheRFcouplerdesign(thesocalledKyhlMethod).

[3]

isanimportantcomponent.AproperRFcouplermustbematchedwiththeregularfeedingwaveguideinordertofeedtheinputmicrowavepowerintotheacceleratingcavitiese ectivelybytuningthecouplingaperture,thesocalled“Match”.Itshouldalsohavesynchronousfrequencyfortheproperphaseadvanceinthewholestructurebytuningthediameterofcou-plingaperture,thesocalled“Tune”.

Originallythecouplerdesignisperformedex-perimentally.However,insuchawayitwillcostonemuchtimeevenforthosewhoareexperiencedintheRFcouplerdesign.Withthewakeandde-velopmentofnumericalelectromagneticCodes,theRFcouplerdesignbasedonnumericalsimulationbe-comespopular.Somenumericalcalculationmethodsbasedon3D-codesuchasMAFIAhadbeendiscussedindetail

[1,2]

2Basictheories

RFcouplerparametersoptimization,infact,isa

.However,bythesemeansitisinconve-processsearchingforthepropervaluesofb,handttorealizethe“Tune”and“Match”ofthecoupler.Herebisthediameterofthecouplercavity,histhe

nienttomodelacomplicated3Dstructure.Theyre-quireexperiencesingeneratingmeshmodelforaccu-