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Fundamentals of the Physical Theory of Diffraction 2007
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Preface The physical theory of diffraction (PTD) is a high-frequency asymptotic technique for the investigation of antennas and scattering problems. This monograph presents the first complete and comprehensive description of the modern PTD based on the concept of elementary edge waves (EEWs). Its subject is the diffraction of acoustic andelectromagneticwavesbyperfectlyreflectingobjectslocatedinahomogeneous losslessmedium. The basic idea of PTD is that:The diffracted field is considered as the radiation generated by the scattering sources (currents) induced on the objects. The so-called uniform and nonuniform scattering sources are introduced in PTD. Uniform sources are defined as sources induced on the infinite plane tangent to the object at a source point.Nonuniformsourcesarecausedbyanydeviationofthescatteringsurfacefrom thetangentplane.Forlarge convex objects with sharp edges, the basic contributions to the scattered field are produced by the uniform sources and by those nonuniform sourcesthatconcentratenearedges(oftencalledfringesources). Theintegrationofuniformsourcesleadstothephysicaloptics(PO)approxima- tionforthescatteredfield.ThePTDisthenaturalextensionofthePOapproximation, taking into accounttheadditional field createdbythenonuniform/fringe sources. Thisbookprovideshigh-frequencyasymptoticsforfringescatteringsourcesand for the scattered field in the far zone. Scattering characteristics are calculated for a variety of objects, such as strips, polygonal cylinders, cones, bodies of revolution withnonzeroGaussiancurvature(includingparaboloidsandsphericalsegments),and finitecircular cylinderswithflatbases. Thetitleofthebookunderlinesthefactthatagreatdealofattentionistobegiven to scattering physics. The derived analytic expressions clearly explain the physical structureofthescatteredfieldanddescribe,indetail,allofthereflectedanddiffracted rays and beams, as well as the fields in the vicinity of caustics and foci.Also, a new fundamentalcomponentofthefield,theso-calledshadowradiation,isintroduced.It isshownthatthiscomponentcontainshalf ofthetotalscatteredpower.Thephysical manifestations of the shadow radiation are the well-known phenomena of Fresnel diffraction andforwardscattering. Plotted numeric results supplement the theory and provide visualizations of the individualcontributionsofdifferentpartsofthescatteringobjectstothetotaldiffracted field.Detailedcommentsexplainallcriticalstepsintheanalyticandnumericcalcula- tionstofacilitatetheirexaminationandutilizationbyreaders.Allchaptersarefollowed by problems for independent investigations, which will be helpful in studying PTD, especiallyfor students. This book is intended for researchers working on antennas and scattering prob- lemsinindustryanduniversitylaboratories.Itcanalsobeusefulforteachingavariety ofuniversitycourses,thatincludetopicsonhigh-frequencyasymptotictechniquesin diffractiontheory.Universityinstructorsandgraduatestudentswillbenefitfromthis bookaswell. Download link：http://www.isload.com.cn/store/a4egq72doduid [ Last edited by zhq025 on 2008-1-16 at 10:56 ] |
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简单回复
juntsing2楼
2008-01-02 21:04
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谢谢分享！