Browsing by Author "Umul, YZ"

Now showing 1 - 6 of 6

Diffraction by a black half plane: Modified theory of physical optics approach
(Optical Soc Amer, 2005) Umul, YZ; Umul, Yusuf Ziya; 42699
The scattered fields from a black half plane which absorbs all the incoming electromagnetic energy are evaluated by defining a new modified theory of physical optics surface current. This current eliminates the reflected fields, coming from the first stationary point of the reflection integral and only creates a reflected diffracted field. The incident scattered fields are found from the same integral, written for the perfectly conducting half plane. The scattered fields are evaluated by using the stationary phase method and edge point technique. The evaluated fields are plotted numerically. (c) 2005 Optical Society of America.
Equivalent functions for the Fresnel integral
(Optical Soc Amer, 2005) Umul, YZ; Umul, Yusuf Ziya; 42699
Fresnel integral is modeled with three equivalent functions. The first function is derived by considering the sum of the first term of the Fresnel integral's asymptotic expansion {(F) over cap (x)} and an exponential function which approaches to infinity at the zero of the Fresnel function's argument and has the properties of a unit step function. The second one is the sum of a unit step function and the transition function defined for the simplified uniform theory of diffraction. The third function considers directly eliminating the infinity coming from (F) over cap (x). The amplitude and the phase of Fresnel integral and its equivalent functions are compared numerically. The result is applied to the modified theory of physical optics solution of the diffraction of edge waves from a half plane problem. (c) 2005 Optical Society of America.
Modified theory of physical optics
(Optica Publishing Group, 2004) Umul, YZ; Umul, Yusuf Ziya; 42699
A new procedure for calculating the scattered fields from a perfectly conducting body is introduced. The method is defined by considering three assumptions. The reflection angle is taken as a function of integral variables, a new unit vector, dividing the angle between incident and reflected rays into two equal parts is evaluated and the perfectly conducting (PEC) surface is considered with the aperture part, together. This integral is named as Modified Theory of Physical Optics (MTPO) integral. The method is applied to the reflection and edge diffraction from a perfectly conducting half plane problem. The reflected, reflected diffracted, incident and incident diffracted fields are evaluated by stationary phase method and edge point technique, asymptotically. MTPO integral is compared with the exact solution and PO integral for the problem of scattering from a perfectly conducting half plane, numerically. It is observed that MTPO integral gives the total field that agrees with the exact solution and the result is more reliable than that of classical PO integral. (C) 2004 Optical Society of America.
Modified theory of physical optics approach to wedge diffraction problems
(Optica Publishing Group, 2005) Umul, YZ; Umul, Yusuf Ziya; 42699
The problem of diffraction from a perfectly conducting wedge is examined with the modified theory of physical optics (MTPO). The exact wedge diffraction coefficient is compared with the asymptotic edge waves of MTPO integral and related surface currents are evaluated. The scattered electric fields are expressed by using these current components. The total, incident and reflected diffracted fields are compared with the exact series solution of the wedge problem, numerically. (C) 2005 Optical Society of America.
Modified theory of the physical-optics approach to the impedance wedge problem
(Optical Soc Amer, 2006) Umul, YZ; Umul, Yusuf Ziya; 42699
The problem of a wedge with equal face impedances is examined with a modified theory of physical optics. The surface integral is constructed by use of the impedance boundary condition. The aperture equivalent current is estimated from the behavior of the reflected diffracted field. The integrals obtained are evaluated asymptotically and compared with the exact solution numerically. (c) 2006 Optical Society of America.
Simplified uniform theory of diffraction
(Optica Publishing Group, 2005) Umul, YZ; Umul, Yusuf Ziya; 42699
Simple exponential functions that approach zero for reflection and shadow boundaries are considered to cancel the infinite values of diffraction coefficients at these regions. This method is applied to a wedge diffraction coefficient, and the resultant uniform coefficient is compared with the exact diffracted fields numerically. (c) 2005 Optical Society of America.