WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Citation - WoS: 4Citation - Scopus: 5Diffraction of Electromagnetic Waves by a Planar Interface Between Perfectly Absorbing and Anomalously Transmitting Metasurface Half-Planes(Elsevier Gmbh, 2019) Umul, Yusuf ZiyaThe interaction process of electromagnetic waves by a planar interface between perfectly absorbing and anomalously refracting metasurface half-planes is investigated. First of all, the scattered geometric optics field is obtained from the difference of the total geometric optics and initial waves. The diffracted fields are determined by using a relation between the scattered geometric optics and diffraction waves at the transition boundaries. It consists of the diffraction fields of perfectly absorbing and anomalously refracting metasurface half-screens. The behaviors of the total, total geometric optics and diffracted waves are studied numerically.Article Citation - WoS: 1Citation - Scopus: 1Interaction of Electromagnetic Waves by a Cylindrical Parabolic Mesh Reflector(Elsevier Gmbh, 2019) Umul, Yusuf ZiyaA cylindrical parabolic reflector, composed of mesh grid, is modeled by a resistive surface. The analysis of the scattered waves is performed by the physical optics integral, which was developed for resistive surfaces. The integral is evaluated asymptotically for large values of the wave-number in high-frequencies. The geometrical optics and diffracted fields are obtained by the methods of stationary phase and edge point respectively. The uniform forms of the diffracted waves are derived. The total wave and its components are investigated numerically for different values of surface resistivity.Article Citation - WoS: 10Citation - Scopus: 11Wave Diffraction by the Junction Between Resistive and Soft-Hard Half-Screens(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaThe scattering process of planes waves by a junction between resistive and soft/hard half-planes is investigated. First of all, the initial and total geometrical optics fields are determined by considering the related geometries. The scattered geometrical optics wave is obtained by subtracting the initial field from the total geometrical optics wave. The diffracted fields are derived by taking into account the behaviour of the geometrical optics wave at the reflection and shadow boundaries. The uniform expressions of the diffracted waves are constructed with the aid of the uniform theory of diffraction. The total field expressions are examined numerically. (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Scattering of Waves by a Soft-Hard Half-Plane Between Isorefractive Medium(Taylor & Francis Ltd, 2017) Umul, Yusuf ZiyaThe scattering of plane waves by a soft-hard half-plane residing between isorefractive medium is studied. The scattered geometrical optics fields are obtained by subtracting the initial geometrical optics fields from the total geometrical optics waves. The diffracted fields are determined by considering the structure of the scattered geometrical optics waves. The uniform expressions for the diffracted fields are derived. The behaviour of the total waves is investigated numerically.Article Citation - WoS: 5Citation - Scopus: 5Wave Diffraction by a Right-Angled Interface Between Resistive Half and Whole Planes(Elsevier Gmbh, Urban & Fischer verlag, 2018) Umul, Yusuf ZiyaThe interaction phenomenon of electromagnetic plane waves by a right angled interface between whole and half screens with different resistivities is studied. The construction, under examination, is considered in order to model various corner discontinuities between transmissive surfaces for indoor wireless communications. First of all, the initial waves, which occur in the absence of the diffracting edge, are determined. Then the scattered geometrical optics fields are obtained by subtracting the initial waves from the total geometrical optics fields. The diffracted field is constructed directly from the scattered geometrical optics wave by a new method. The resultant field expressions are examined numerically.Article Citation - WoS: 1Citation - Scopus: 1Wedge Diffraction Model in Gravitational Lensing by Cosmic Strings(Elsevier Gmbh, 2018) Umul, Yusuf ZiyaA cosmic string forms a conical topology, which enables a diffraction phenomenon by a wedge with an inner angle, equals to the double of the deficit angle. A wedge, on the edge of which the string is located, is defined in the flat space-time. The radiated wave from a star is represented by two plane waves, propagating on the two surfaces of the wedge for grazing incidence. The uniform expressions of the diffracted waves are obtained and investigated numerically. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - Scopus: 1Diffraction of Waves by a Conductive Half-Plane(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaThe scattering process of plane waves by a conductive half-plane is investigated. The scattered geometrical optics waves are obtained by subtracting the incident field from the total geometrical optics waves. The physical optics integral is constructed from the scattered geometrical optics fields. The diffracted waves are evaluated by the application of the edge point method to the physical optics integral. A correction field is added to the diffracted waves in order to satisfy the conductive boundary conditions on the surfaces of the half plane. The uniform diffracted fields are evaluated and the resultant scattered waves are compared with the literature numerically. (C) 2016 Elsevier GmbH. All rights reserved.Article Wave Diffraction by a Metallic Half-Plane(Elsevier Gmbh, Urban & Fischer verlag, 2016) Umul, Yusuf ZiyaThe scattering problem of plane waves by a half-screen with different face impedance is obtained with a geometrical optics-physical optics based method. The kernel of the physical optics integral is redefined by using coefficients that guarantee the satisfaction of the boundary condition on the surface of the scatterer. The uniform diffraction fields are obtained and the behavior of the scattered waves is investigated numerically for different values of the surface impedance. (C) 2015 Elsevier GmbH. All rights reserved.Article Scattering of Waves by an Aperture in an Impedance Screen(Elsevier Gmbh, Urban & Fischer verlag, 2012) Umul, Yusuf ZiyaThe transmission and diffraction of waves by an aperture in an impedance screen is investigated. The Senior's solution of the scattering problem of waves by an impedance half-plane is transformed into a physical optics type integral. The obtained method is applied to the transmission problem of waves by a slit in an impedance screen. The results are compared with the aperture problem in black and conducting screens numerically. (C) 2012 Elsevier GmbH. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 9Babinet's Principle in the Fraunhofer Diffraction by a Finite Thin Wire(Elsevier Gmbh, Urban & Fischer verlag, 2011) Umul, Yusuf ZiyaThe scattered waves by a thin finite wire are evaluated by using the Rayleigh-Sommerfeld integral in the Fraunhofer approximation. The scattered fields by the complementary thin wire are also obtained with the aid of the Babinet's principle. The scattering integrals are evaluated directly. It is shown that Babinet's principle holds excellently for this problem. The scattered fields are examined numerically. (C) 2010 Elsevier GmbH. All rights reserved.