Browsing by Author "Umul, Y. Z."

Now showing 1 - 8 of 8

Citation - WoS: 8
Citation - Scopus: 9
Diffraction 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.
Citation - WoS: 4
Citation - Scopus: 4
ELECTRIC CHARGES THAT BEHAVE AS MAGNETIC MONOPOLES
(E M W Publishing, 2010) Umul, Y. Z.; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The memristor theory of Chua [1] provides a connection with the charge and magnetic flux in an electric circuit. We define a similar relation for the electric and magnetic flux densities in electromagnetism. Such an attempt puts forward interesting results. For example, the magnetic charges do not exist in nature however the electric charges behave as the magnetic monopoles in special media. We support our theory with the results of the recent experiments on materials named as spin ice.
Citation - WoS: 7
Citation - Scopus: 8
Fringe waves radiated by a half-plane for the boundary conditions of Neumann
(Springer Heidelberg, 2008) Umul, Y. Z.; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The fringe waves of the physical theory of diffraction are obtained in terms of Fresnel integrals for a half-plane satisfying the Neumann boundary condition. The approximate expressions of the radiated waves are also evaluated for sufficiently large wavenumbers. The fields are plotted and compared numerically.
Citation - WoS: 9
Citation - Scopus: 9
Physical optics scattering of waves by a half-plane with different face impedances
(Ieee-inst Electrical Electronics Engineers inc, 2011) Umul, Y. Z.; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The theory of physical optics is extended for the diffraction problem of waves by a half-plane with different face impedances. The kernel of the modified theory of physical optics integral is expressed in terms of the Maliuzhinets function. The resultant integral is evaluated asymptotically for large values of the wavenumber. The results are examined numerically.
Citation - WoS: 3
Radiation of scalar waves by the discontinuities in the antenna geometries
(Springer, 2010) Umul, Y. Z.; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The electrical scalar potential satisfies the Helmholtz equation for time-harmonic waves and Aharonov-Bohm showed that the electromagnetic potentials have physical reality. For these reasons, the scalar potential represents scalar wave propagation in space. The gradient of the scalar wave leads to the electric field intensity, but it does not create the magnetic field. The criteria for the radiation of the scalar waves are studied on various linear antennas. The radiation integrals of the antennas are evaluated asymptotically by taking into account the edge effects. The radiation diagrams are plotted numerically and the phase velocities of the scalar waves are investigated in the near field.
Citation - WoS: 18
Citation - Scopus: 19
Scattering by an impedance half-plane: Comparison of the solutions of Raman/Krishnan and Maliuzhinets/Senior
(Electromagnetics Acad, 2009) Umul, Y. Z.; Umul, Yusuf Ziya; Elektronik ve Haberleşme Mühendisliği
There are three approaches for the solution of the diffraction problem of plane waves by an impedance half-plane in the literature. The diffracted field expressions, obtained by the related methods, are compared numerically. The examination of the scattered field shows that the most reliable solution is the field representation of Raman and Krishnan. Since the diffracted fields of Senior and Maliuzhinets do not compensate the discontinuities of the geometrical optics waves at the transition regions.
Citation - WoS: 13
Citation - Scopus: 13
The effect of impedance boundary conditions on the potential function of the boundary diffraction wave theory
(Elsevier, 2008) Umul, Y. Z.; Umul, Yusuf Ziya; Yalcin, U.; 42699; 156567; Elektronik ve Haberleşme Mühendisliği
A novel potential function of the boundary diffraction wave theory is obtained for the impedance surfaces by the asymptotic reduction of the modified theory of physical integrals. The function is expressed in terms of the direction vectors of the incident and scattered rays. The application of the method is performed on the problem of diffraction of plane waves by an impedance half plane for oblique incidence. (c) 2007 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
The physical optics integral of creeping waves
(Taylor & Francis Ltd, 2012) Umul, Y. Z.; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The creeping waves, occurring in surface diffraction, are expressed as a physical optics surface integral. The scattering geometry and the implications of the surface integral are investigated in the context of the diffraction theory. The method is applied to the scattering problems of plane waves by an infinite parabolic conducting reflector. The results are analyzed numerically.