Calculation of the scattered fields from a pec parabolic reflector by the extended boundary diffraction wave theory


Thesis Type: Postgraduate

Institution Of The Thesis: Bursa Uludağ University, FEN BİLİMLERİ ENSTİTÜSÜ, Turkey

Approval Date: 2014

Thesis Language: Turkish

Student: Can Altıngöz

Supervisor: UĞUR YALÇIN

Abstract:

The scattered fields from a perfect conducting parabolic reflector are calculated in this study. First the diffracted fields and then the reflected fields are calculated seperately. Boundary Diffraction Wave Theory(BDWT) is a widely used approach for Electromagnetic/Optic diffraction problems. The theory needed improvements as it does not give satisfactory solutions for diffracted fields from perfect conducting and impedance surfaces, since the theory is based on opaque screen. In this work the diffracted fields from a perfect conducting parabolic reflector are calculated by the Extended Boundary Diffraction Wave Theory(EBDWT) which is developed from BDWT. A linear current source is used in this study. First the diffracted fields are calculated. A new vector potential is generated and used in the calculation of the scalar electric/magnetic field for the observation point. The field expression is taken in Helmholtz-Kirchoff integral form. By applying the Stokes theorem, the field expression can be written as the sum of the edge diffracted field and the geometrical optic field. The obtained diffracted field expression results in a non-uniform structure. The non-uniform field expression is converted to uniform structure by using the fresnel function. Secondly, the reflected field is calculated by the modified theory of physical optics approach. Finally, variation of the incoming, diffracted and reflected fields are observed for different incoming angles and different focus lengths. The diffracted and reflected fields are compared with the literature. The diffracted, reflected and the incoming fields are examined numerically by Matlab.