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ID:40848210
大小:1.19 MB
页数:13页
时间:2019-08-08
《Multipath EM scattering from breaking ocean waves at grazing incidence外文》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、RadioScience,Volume32,Number4,Pages1455-1467,July-August1997MultipathEMscatteringfrombreakingoceanwavesatgrazingincidenceJ•mesC.WestElectricalandComputerEngineering,OklahomaStateUniversity,StillwaterMarkA.SlettenNavalResearchLaboratory,Washington,D.C..Abstract.Theelectromagneticscatteringfromabre
2、akingwaterwavewithneargrazingilluminationhasbeenexaminedusingbothexperimentalmeasurementandnumericalcalculation.Thescatteringfromametalmodelofabreakingwaveof1.2mwavelengthwascharacterizedatgrazinganglesrangingfrom0øto25oandatfrequenciesrangingfrom6GHzto12GHz.Strongmultipathinterferenceisobservedi
3、ntheverticalpolarization(VV)backscatterandmuchweakerinterferenceisseeninthehorizontalpolarization(HH)backscatter.Scatteringfromthewaveprofilebothwithandwithoutthebreakingplumeshowsthattheplumeisthedominantscatteringfeature.Numericalcalculationofthescatteringfrommodifiedsurfaceprofilesshowsthatthe
4、interferenceisduetomultipathscatteringfromtheplumeandfrontfaceofthewave.HHinterferenceissubstantiallysmallerthanthatofVVbecausethescatterfromtheplumeinthemultipathdirection(towardthefrontface)isgreatlyreducedowingtotheconductingsurfaceboundaryconditions.Therelativelevelsoftheplumeandexpecteddistr
5、ibuted-surfacescatteringareconsistentwiththewave-tankmeasurementofhorizontallypolarizedseaspikesfrombreakingwavesofthisscale.1.Introductionpolarization(VV)andcanlastforperiodsofuptoElectromagneticscatteringfromtheoceansurface1s.StrongHHseaspikescanraisethebackscatterisnotwellunderstoodwhentheillu
6、minationgrazingtoabovethatatVV,behaviorthatisnotpredictedangleissmall(lessthanabout20ø).Scatteringmod-bytheBragg-resonancemechanismthatisthebasisofthetwo-scalemodel.elssuchasthetwo-scalemodelValenzuela[1968]thataccuratelypredictthescatteringatmoderategraz-Severalmechanismshavebeensuggestedtoex-in
7、ganglesfailatsmalleranglesGuinardandDaleyplainthesmall-grazingscattering,includingwedge[1970].Infact,itappearsthattheprimaryscatter-diffraction[Lyzengaetal.,1983;KalmykovandPust-ingmechanismsareentirelydifferentatmoder
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