地面、沙漠的电磁散射特性研究

《地面、沙漠的电磁散射特性研究》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、摘要摘要本文首先给出了粗糙面散射的基本理论，给出了随机粗糙面和沙丘的生成方法，介绍了粗糙面散射的基本方法基尔霍夫近似和微扰法；给出了沙漠的纵向沙丘和横向沙丘散射模型，推导了沙丘间多次散射的后向散射系数公式并分析了随波长、介电常数、高度均方根、相关长度和散射系数角分布的变化，与双尺度计算结果进行了比较。利用四成分模型计算了土壤湿度与土壤介电常数的关系，并分别用基尔霍夫近似法和微扰法计算了考虑不同土壤类型的电磁散射。基于基尔霍夫标量近似法和驻留相位近似法研究了粗糙面下方介质中的电磁透射和散射，导出了不同极化状态下

2、指数谱粗糙面透射系数计算公式并进行了数值计算和讨论。最后利用微扰法计算了分层地面模型的一阶散射场，对其进行了详细讨论并与单层模型的散射系数进行了比较。关键词：粗糙地面，沙漠，电磁散射，微扰法，分层粗糙面，透射系数AbstractInthisthesis，fundamentaltheoryofelectromagneticscatteringfromtheroughsurfaceiSintroducedforrandomroughsurfacemodelsandelectromagneticscattering

3、models，suchaSKirchhoffApproximationandSmallPerturbationApproximation．Modelsoflongitudinalduneandtransverseduneonthedesertarepresented．Backscatteringcoe伍cientofmultiplescattenngbetweendunesisderived．neinfluencesofwavelength，dielectricconstant,meansquareroot,

4、correlationlengthandslopeangularonthescatteringcoefficientfromtheroughsurfaceswithExponentialspectrumareanalyzed,andnumericalresultsarecomparedwithTwo—ScaleModelfordifferentdesertmodels．Accordingtothefour-elementmodel，therelationbetweenhumidityanddielectric

5、constantofsoiliSpresentedandelectromagneticscatteringfromsoilsurfaceiscalculatedatdifferentsoilsbyKirchhoffandSmallPerturbationMethod．BaSedonScalarApproximationandStationary—PhaseApproximation,electromagneticscatteringandtransmissioninthemediumunderroughsur

6、faceareinvestigatedandformulaeoftransmissioncoefficientsfordifferentpolarizationsarepresentedanddiscussednumerically．111ediagramofthescatteringcoefficientfordifferentpolarizationtransmissionwaveconsideringExponentialspectrum、析mvaryingofthescatteringangle，th

7、escatteringazimuthangleandthefrequencyoftheincidentwaveisobtainedbynumericalimplementation．Finally,thefirstorderelectromagneticscatteringfromlayeredmodelroughsurfacesisalsoexaminedbyapplyingtheSmallPerturbationMethodandthecomparisonofscatteringcoefficientsf

8、orthelayeredmodelandsurfacereflectionaregivenanddiscussedindetail．Keywords：Roughlandsurface，Desert，Electromagneticscattering,SPM，Layeredroughsurface，TransmissionCoefficient创新性声明本人声明所呈交的论文是我个人在导师指导下进行的研