محاسبه سطح مقطع راداري يك جسم PEC با پوشش عايق داراي تقارن محوري

چكيده انگليسي :

RCS Calculation of Dielectric Coated PEC Objects with Axial Symmetry Hossein Mohammadzadeh h mohammadzadeh@ec iut ac ir Date of Submission 2013 1 21 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr Abolghasem Zeidaabadi Nezhad zeidabad@cc iut ac ir Abstract The Radar Cross Section RCS of a target has an important role in detection of targets by radar RCS includes the feature of size and geometrical shape of the target There are several methods for calculating the RCS The different electromagnetic techniques are based on Maxwell s equations These methods generally are classified into two categories The first is rigorous methods numerical technique analysis and the second is approximate methods high frequency asymptotic methods The rigorous techniques such as the Method of Moments MoM the Finite Difference Time Domain FDTD or the Finite Element Method FEM derive an exact numerical solution of the problem However these techniques are based on the discretization of the geometry in differential elements Therefore for large structures relative to the size of the wavelength the computational resource requirements increase and these techniques become limited by the availability of computational resources On the other hand the asymptotic techniques approximate Maxwell s equations to a solution whose accuracy increases with frequency The main advantage of these methods is that the computational cost remains constant as the frequency increases while as has been mentioned the accuracy of the result increases Therefore these methods are especially suitable for analyzing electrically huge problems Another advantage of asymptotic methods is physically clear expressions and concept realization to the mechanisms of radiation and scattering While use of the numerical method gives only a complete solution to the problem Such as high frequency methods are Geometrical Optics GO Physical Optics PO Geometrical Theory of Diffraction GTD Uniform Geometrical Theory of Diffraction UTD and Physical Theory of Diffraction PTD Asymptotic methods are classified into two categories the current based and the field based In the field based methods such as GO GTD and UTD since using ray concept for describing electromagnetic wave propagation field at Incident Shadow Boundary ISB and Reflection Shadow Boundary RSB is discontinuous and also field includes caustic point or line So the current based methods such as PO and PTD can be used to overcome these problems In this thesis we calculate the RCS of dielectric coated Perfect Electric Conductor PEC objects with axial symmetry But in this thesis we ignore of the diffraction field of the surface body and only calculate the scattering field from the surface body and diffraction field from the edges since the diffracted field of the surface body is related to the Green s function of the body The main advantage of the methods presented in this thesis is the use of the Stationary Phase Method SPM to calculate the PO and PTD integrals which increased speed of computation relative to the numerical integration Comparison of results achieved from the PO PTD method with numerical results achieved from FEKO software shows that the presented method is more accurate Key Words Radar Cross Section RCS Asymptotic technique Physical Optics PO approximation Physical Theory of Diffraction PTD Stationary Phase Method SPM

محمدزاده، حسين

محاسبه سطح مقطع راداري يك جسم PEC با پوشش عايق داراي تقارن محوري

روش مجانبي , تقريب PO , روش PT D , روش فاز ايستا