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基于NURBS建模的抛面天线波束赋形.docx

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基于NURBS建模的抛面天线波束赋形 Abstract: ThispaperdiscussesthebeamshapingofaparabolicantennausingNURBSmodelingtechniques.TheNURBS(Non-UniformRationalB-Spline)approachprovidesexcellentcontroloverthecurvatureoftheantennareflectorsurface,whichcanbeusedtoshapetheradiationpatternoftheantenna.ThepaperreviewsthetheorybehindNURBScurvesandsurfaces,andprovidesanoverviewofhowthesesurfacescanbeusedtomodelthereflectorofaparabolicantenna.Finally,thepaperpresentsacasestudyinwhichtheNURBSmodelingmethodisusedtodesignandsimulatethebeamshapingofaparabolicantenna,demonstratingtheefficacyofthisapproach. Introduction: Parabolicantennasarewidelyusedinthefieldoftelecommunicationsfortheirhighgain,directivityandnarrowbeamwidth.Theradiationpatternofaparabolicantennacanbeshapedbyadjustingthecurvatureofthereflectorsurface.Conventionally,parabolicreflectorsaredesignedusingsmoothcurvessuchasconicsectionsandcirculararcs,whichcanbeaccuratelydefinedbygeometricequations.However,theseequationsdonotprovidesufficientflexibilityintheshapeofthereflectorrequiredtoachieveadesiredradiationpattern. Non-UniformRationalB-Splines(NURBS)areamodelingtechniquethatprovideahighdegreeofflexibilityandprecisioninthecontrolofsurfaceshape,andarewell-suitedforantennadesign.NURBScurvesandsurfacesaredefinedmathematicallyusingcontrolpoints,weightsandknotvectors,whichcanbemanipulatedtocontrolthegeometryofthesurface.Inthispaper,wepresentamethodforthemodelingofparabolicreflectorsurfacesusingNURBScurvesandsurfaces. TheoryofNURBS: NURBSareatypeofsplinefunctionusedtorepresentsmoothlyvaryingcurvesandsurfaces.Theyaredefinedasaweightedsumofbasisfunctions,whichareconstructedfrompolynomials,makingthembothflexibleandprecise.TheNURBSbasisfunctionsprovideamethodofinterpolationthatallowsthesurfacetopassthroughasetofcontrolpoints.Theweightsattachedtoeachcontrolpointdeterminetheinfluenceofthatpointontheshapeofthesurface. Theknotvectorisasequenceofparametervaluesthatdividethecurveorsurfaceintosegments.Theknotvectordefinesthedegreeofcontinuitybetweenthecur