WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Citation - WoS: 2Citation - Scopus: 8Scattering of Electromagnetic Waves by an Impedance Sheet Junction in Anisotropic Plasma(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe diffraction of electromagnetic plane waves by the edge discontinuity of an impedance sheet junction, which is located in an anisotropic plasma, is investigated. The problem is solved by the integral theory of diffraction. The scattering integral is obtained from the scattered geometric optics wave. The diffracted fields are derived by the edge point evaluation of the scattering integral. The evaluated field expressions are analyzed numerically.Article Propagation and Diffraction of Surface Plasmons on a Resistive Half-Plane(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaThe propagation, radiation and diffraction characteristics of surface plasmons, on a discontinuous dielectric layer, are investigated. The layer is modeled by a resistive surface. The physical optics based formulation of the surface waves is taken into account. The physical optics integral includes the propagating and diffracting fields. These wave components are evaluated asymptotically and their behaviors are studied numerically.Article Citation - WoS: 1Citation - Scopus: 2Physical Optics Approach To Wave Diffraction by a Perfect Electromagnetic Conductor Half-Plane(Springer, 2021) Umul, Yusuf ZiyaThe scattering of electromagnetic plane waves by a perfect electromagnetic conductor is investigated. The method of physical optics is used for the analysis of the problem. The reflected fields by a whole-plane are taken into account. The surface electric and magnetic current densities are constructed with the aid of the incident wave and the reflected field from the whole-surface. The scattering integrals are obtained for the electric and magnetic vector potentials. The scattered electric and magnetic fields are expressed in terms of the vector potentials. The scattering integrals are evaluated asymptotically for large values of the wave-number. Some numerical results are given.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: 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 Modified Theory of Physical Optics Approach To Impedance Surfaces for Skew Incidence(Elsevier Gmbh, 2020) Umul, Yusuf ZiyaA three dimensional modified theory of physical optics integral is constructed for the impedance surfaces, illuminated by a plane wave for skew incidence. The scalar fields are taken into account. The kernel of the physical optics integral is evaluated by using a relation with the geometric optics waves and stationary phase evaluation of the integral. The obtained surface integral is applied to the diffraction problem of waves by an impedance half-plane. The scattered fields are investigated numerically.Article Citation - WoS: 7Citation - Scopus: 9Rubinowicz Transform of the Mtpo Surface Integrals(Elsevier Science Bv, 2008) Umul, Yusuf Z.The surface integral of the modified theory of physical optics is reduced to a line integral by using the Rubinowicz transform for the incident scattered fields by an arbitrary aperture in a black surface. The integral theorem of Kirchhoff is applied to the scattering geometry and the diffracted fields are expressed in terms of a line integral along the contour of the diffracting edge. (C) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Exact Form of the Physical Optics Integral(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaThe exact structure of the physical optics integral is obtained. With this aim, the rigorous solution of the diffraction problem of waves by a perfectly conducting half-plane is considered. The Fresnel integrals of the incident and reflected scattered fields are transformed into the physical optics integrals by defining a suitable variable transform. The relation of the obtained integral with the modified theory of physical optics is discussed. (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 5Modified Theory of Physical Optics and the Correction Terms of the Physical Theory of Diffraction(Elsevier Gmbh, 2018) Umul, Yusuf ZiyaThe methods of physical optics and physical theory of diffraction are reviewed for electromagnetic waves. The Fermat principle and its' modified version are investigated and the necessity of the introduction of a variable unit vector is put forth. The scattering integrals of modified theory of physical optics are reviewed in this context. Recent comments on the modified theory of physical optics are discussed and refuted clearly. A proof is given on the nature of the physical theory of diffraction's correction terms. The proof is visualized with some numerical simulations.