ansoft hfssboundary and excitation training外语英文电子书

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

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

3、FieldvectorsarediscontinuousÑ×D=rDerivativesofthefieldvectorshavenomeaningÑ×B=0BoundaryConditionsdefinethefieldbehavioracrossdiscontinuousboundaries2BoundaryConditionsWhydoICare?TheyForcethefieldstoalignwiththedefinitionoftheboundaryconditionAsauserIsh

4、ouldbeaskingWhatassumptions,aboutthefields,dotheboundaryconditionsmake?Aretheseassumptionsappropriateforthestructurebeingsimulated?ModelScope/ComplexityTheinfinitespaceoftherealworldneedstobemadefiniteAnsoftHFSSBackgroundorOuterboundaryWhenappliedprope

5、rly,theycanbeusedtoreducethecomplexitySolutionTimeComputerResourcesFailuretounderstandboundaryconditionsmayleadtoinconsistentresults3BoundaryConditionsApplicationofBoundaryConditions-Case1EmulatelaboratorymeasurementsVerification/Validationbeforeproduc

6、tionPicturecourtesyofTektronixPicturecourtesyofDelphi4BoundaryConditionsApplicationofBoundaryConditions-Case2Isolatepartofastructure(i.e.Excitingarbitrarytransmissionlines)NotphysicallypossibletomeasureinthelaboratoryFull-Waveanalysisnotrequiredfortota

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

8、ApproximationsLargelytheusersresponsibilitySymmetryPlanesPerfectElectricorMagneticSurfacesRadiationSurfacesBackgroundorOuterSurfaceMaterialPropertiesBoundarybetweentwodielectricsTransparenttotheuserFiniteConductivityofaconductor6Example