Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651

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Publisher: search.filters.publisher.Elsevier GmbhSubject: search.filters.subject.Physical Optics

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Now showing 1 - 10 of 10
  • Article
    Citation - WoS: 2
    Citation - Scopus: 8
    Scattering of Electromagnetic Waves by an Impedance Sheet Junction in Anisotropic Plasma
    (Elsevier Gmbh, 2020) Umul, Yusuf Ziya
    The 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 Ziya
    The 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
    Wave Diffraction by an Impedance Wedge
    (Elsevier Gmbh, 2020) Umul, Yusuf Ziya
    A 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: 1
    The Factorization Process in the Modified Theory of Physical Optics
    (Elsevier Gmbh, 2020) Umul, Yusuf Ziya
    The 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: 4
    Citation - Scopus: 5
    Surface Wave Contribution in Physical Optics Type Scattering Integrals
    (Elsevier Gmbh, 2020) Umul, Yusuf Ziya
    The 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 Ziya
    A 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: 3
    Citation - Scopus: 5
    Modified Theory of Physical Optics and the Correction Terms of the Physical Theory of Diffraction
    (Elsevier Gmbh, 2018) Umul, Yusuf Ziya
    The 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.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 13
    Three Dimensional Modified Theory of Physical Optics
    (Elsevier Gmbh, 2016) Umul, Yusuf Ziya
    The three dimensional version of the modified theory of physical optics is introduced with the aid of a Green's function that satisfies the Helmholtz equation in local spherical coordinates. The algorithm which leads to the construction of the scattering integral is given. The method is applied to the three dimensional diffraction problem of plane waves by a perfectly conducting half-plane. The comparison of the resulting field expressions with the literature shows that the modified theory of physical optics leads to the exact solution. (C) 2015 Elsevier GmbH. All rights reserved.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 4
    The Physical Optics Integral on the Scatterer's Unlit Surface
    (Elsevier Gmbh, 2014) Umul, Yusuf Z.
    The scattering integrals of the modified theory of physical optics are redefined according to the illuminated and unlit surfaces of the scattering object. With this aim the canonical problem of wedge diffraction is taken into account. It is shown that the new scattering integral contain two geometrical optics and diffracted fields. One of the geometrical optics waves is the reflected field component that propagates in the real space. The other one transmits to an imaginary space through the scattering surface and does not have any influence in the real space. The diffracted waves exist in the real space and satisfy the related boundary condition on the scattering surfaces. The resultant field expressions are compared with the exact series solution of the problem numerically. (C) 2014 Elsevier GmbH. All rights reserved.
  • Article
    Scattering of Waves by an Impedance Half-Plane: Single Effect of Face Impedances
    (Elsevier Gmbh, 2013) Umul, Yusuf Ziya
    The modified theory of physical optics integral, obtained in the diffraction process of plane waves by an impedance half-plane, is decomposed into sub-integrals. The sub-integrals are evaluated asymptotically. Their physical meanings are interpreted. The different components of the scattered waves are examined numerically. (C) 2012 Elsevier GmbH. All rights reserved.