HFSSv9边界条件和激励设置培训

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1、BoundaryandExcitationTrainingFebruary20031BoundaryConditionsWhyareTheyCritical?Formostpracticalproblems,thesolutiontoMaxwell’sequationsrequiresarigorousmatrixapproachsuchastheFiniteElementMethod(FEM)whichisusedbyAnsoftHFSS.ThewaveequationsolvedbyAnsof

2、tHFSSisderivedfromthedifferentialformofMaxwell’sequations.Fortheseexpressionstobevalid,itisassumedthatthefieldvectorsare:single-valued,bounded,andhavea¶BÑ´E=-continuousdistribution(alongwiththeirderivatives)¶t¶DÑ´H=J+Alongboundariesofmediaoratsources,

3、¶tFieldvectorsarediscontinuousÑ×D=rDerivativesofthefieldvectorshavenomeaningÑ×B=0BoundaryConditionsdefinethefieldbehavioracrossdiscontinuousboundaries2BoundaryConditionsWhydoICare?TheyForcethefieldstoalignwiththedefinitionoftheboundaryconditionAsauser

4、IshouldbeaskingWhatassumptions,aboutthefields,dotheboundaryconditionsmake?Aretheseassumptionsappropriateforthestructurebeingsimulated?ModelScope/ComplexityTheinfinitespaceoftherealworldneedstobemadefiniteAnsoftHFSSBackgroundorOuterboundaryWhenappliedp

5、roperly,theycanbeusedtoreducethecomplexitySolutionTimeComputerResourcesFailuretounderstandboundaryconditionsmayleadtoinconsistentresults3BoundaryConditionsApplicationofBoundaryConditions-Case1EmulatelaboratorymeasurementsVerification/Validationbeforep

6、roductionPicturecourtesyofTektronixPicturecourtesyofDelphi4BoundaryConditionsApplicationofBoundaryConditions-Case2Isolatepartofastructure(i.e.Excitingarbitrarytransmissionlines)NotphysicallypossibletomeasureinthelaboratoryFull-Waveanalysisnotrequiredf

7、ortotalsystemOrtotalsystemtoocomplexDesignwork/ComponentleveloptimizationPostproductionproblemsolvingTotalSystemIsolatedComponent–ViaTransition5BoundaryConditionsWhatareCommonAnsoftHFSSBoundaryConditions?SourcesWavePorts(External)LumpedPorts(Internal)

8、SurfaceApproximationsLargelytheusersresponsibilitySymmetryPlanesPerfectElectricorMagneticSurfacesRadiationSurfacesBackgroundorOuterSurfaceMaterialPropertiesBoundarybetweentwodielectricsTransparenttotheuserFiniteConductivityofaconductor6Example