WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Citation - WoS: 8Citation - Scopus: 9Diffraction of Waves by an Impedance Half-Plane(Elsevier Science Bv, 2013) Umul, Y. Z.The solution of the diffraction problem of waves by an impedance half-plane that satisfies the impedance boundary condition is obtained for the first time in the literature. A reflection coefficient which is the function of the angular and spatial variables in the polar coordinates is defined and its exact expression is obtained with the aid of the impedance boundary condition. The resultant diffraction field is compared with the solution of Malyuzhinets numerically and their differences are stressed. The structures of the total scattered, geometrical optics and diffracted waves are also investigated. (C) 2013 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 2Wave Diffraction by a Thin Lossy Dielectric Half-Plane(Elsevier Gmbh, 2021) Umul, Yusuf ZiyaThe scattering of electromagnetic waves by a thin lossy dielectric half-plane is investigated. With this aim, the interaction process of waves with a dielectric layer is studied. The reflection and transmission coefficients are obtained in the limiting case, which is defined when the thickness of the layer is sufficiently smaller than the wavelength. The diffracted waves by the half-plane are evaluated using the method of transition boundary. Some numerical results are given. We will study the interaction problem of electromagnetic waves by a thin lossy dielectric half-plane in this paper. It will be supposed that the width of the dielectric layer is sufficiently smaller than the wavelength of the incident field. In the literature, such a structure is modeled by the resistive boundary conditions [1]. The scattering of waves by a resistive half-plane has been investigated in the literature by some authors [2-9]. Rawlins [10] solved the diffraction problem of plane waves by a thin dielectric half-screen by using approximate boundary conditions. Anderson [11] studied the same scenario and obtained a solution with the method of dual integral equation. A Wiener-Hopf approach was applied by Chakrabarti [12] to the dielectric half-plane, illuminated by a plane electromagnetic wave. Senior and Volakis [13] derived approximate boundary conditions for a thin dielectric layer and applied them to the diffraction problem, under consideration, for magnetic polarization [14]. We will take into consideration a lossy dielectric layer with finite width d and derive the reflected and transmitted electromagneticArticle Citation - WoS: 1Citation - Scopus: 1Wave Diffraction by a Perfect Magnetic Conductor Half-Plane Between Free Space and Anisotropic Plasma(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe diffraction of magnetic polarized electromagnetic plane waves by a perfect magnetic conductor half-screen, located between free space and anisotropic plasma, is studied. The method of transition boundary is used for the solution of the problem. The scattered GO wave is obtained. The diffracted fields are derived with the aid of the scattered GO wave. The uniform expressions of the edge diffracted waves are derived. The behaviors of the evaluated fields are investigated numerically.Article Citation - WoS: 2Citation - Scopus: 3Diffraction by an Interface Between Perfect Electromagnetic Conductor and Conductive Surfaces(Elsevier Gmbh, 2021) Umul, Yusuf ZiyaThe interaction of electromagnetic plane waves by a planar interface between conductive and perfect electromagnetic conductor half-planes is investigated. The method of transition boundary is used for the solution of the problem. The geometry, under consideration, is divided into two parts by using a relation, obtained for a perfect electromagnetic conductor half-plane. After obtaining the diffracted fields for sub-problems, they are combined into a single field for the coand cross-polarized waves. The behaviors of the total field and its components are analyzed numerically.Article Citation - WoS: 1Citation - Scopus: 1Diffraction by an Anomalously Perfect Reflecting Metasurface Half-Plane(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe scattering process of plane waves by a half-plane, composed of anomalously perfect reflecting surfaces, is investigated. The solution of the problem is obtained in an original way. The boundary condition of the problem is also taken into account in the construction of the edge diffracted field. The limiting case of the problem is the diffraction of waves by a perfect electric conductor half plane. The obtained field expression are analyzed numerically.Article Wave Diffraction by an Impedance Wedge(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaA new diffraction field expression is proposed for a wedge with different face impedances. The modified theory of physical optics based diffraction coefficient is taken into account. The reflection coefficients are expressed in terms of the split functions that occur in the double integral solution of the resistive half-plane problem. The effects of wedge's each faces are represented separately. The uniform field expression is obtained and compared with the literature for a right-angled impedance wedge numerically.Article Citation - Scopus: 1The Factorization Process in the Modified Theory of Physical Optics(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe factorization process is integrated to the procedure of the modified theory of physical optics. The scattering integral for the diffraction problem of waves by a soft half-plane is taken into account. The values of the kernel is obtained for two special values of the scattering angle beta. By considering the behavior of the integrand at these special values, a technique for the factorization process is determined. The new approach is applied to the problems of hard, impedance and conductive half-screens.Article Citation - WoS: 8Citation - Scopus: 8Scattering of Waves by a Perfect Electric Conductor Half-Screen in an Anisotropic Medium(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe scattering process of electromagnetic plane waves by a perfect electric conductor half-plane, in an anisotropic medium, is studied. The technique, used for the solution of the problem, is the method of transition boundary. The values of an unknown function, which constructs the diffracted wave, are found at the reflection and shadow boundaries. The function is determined by applying a factorization process with the reciprocity principle. A new diffraction field is derived by the mentioned method. Some numerical results are given.Article Citation - WoS: 4Citation - Scopus: 5Surface Wave Contribution in Physical Optics Type Scattering Integrals(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe contribution of the poles in a real valued physical optics integral is investigated. First of all, a complex integral of scattered waves is taken into account. The edge diffracted and surface wave components are evaluated by the methods of saddle point and Cauchy integral theorem. The physical optics integral is constructed with the aid of the asymptotic expressions of the edge diffraction field. A second PO integral is obtained for the surface waves. The theory is applied to an impedance half-plane.Article Diffraction of Waves by a Discontinuous Edge Contour(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaAn edge contour which is discontinuous is taken into account. The geometric optics and edge diffracted waves are obtained for the oblique incidence of a plane wave. The discontinuity in the geometry is expressed in terms of a unit step function. By using a property of the Fresnel function, the corner diffracted field is expressed.