26 research outputs found
Education and Human Resources Strategy for the Vision 2023 Technological Foresight study of Turkey
2007 IEEE Meeting the Growing Demand for Engineers and Their Educators 2010-2020 International Summit, MGDETE 2007 --9 November 2007 through 11 November 2007 -- Munich --This paper gives an overview of education system and R&D system in Turkey with the statistical information of public organizations. Turkey is working hard to become a technology producing competitive country in the global economy. The main tasks are to improve both the quantity and quality of education at all levels and grow highly qualified human resources. For these purposes, policy proposals are introduced which were based mainly on the Education and Human Resources Strategy Report of Vision 2023 Technology Foresight of Turkey. © 2007 IEEE
An Extension to GTD for an Edge on a Curved Perfectly Conducting Surface
The construction of a high-frequency solution for the generation of edge-diffracted space rays and edge-excited surface rays by Ana electromagnetic wave normally incident on the edge of a curved perfectly conducting surface surrounded by an homogeneous medium is considered. The solution is a collection of the results of second degree canonical problems considered by idemen e? ul. which will be cast into forms appropriate to numerical applications. Copyright © 1986 by The Institute of Electrical and Electronics Engineers, Inc
DIFFRACTION COEFFICIENTS FOR A CURVED EDGE WITH SOFT AND HARD BOUNDARY CONDITIONS.
Diffraction of high-frequency electromagnetic fields is important from both the theoretical and engineering points of view. Generally, asymptotic methods are preferred for the solution of diffraction problems because rigorous analysis is generally impossible. The diffraction of whispering gallery modes by the edge of a conducting spherical reflector with soft and hard boundary conditions is considered separately, where the incident modes are assumed to be present in the concave side of the reflector. The analysis has been done for the special case when (ka) is much larger than 1 by using the locality principle of the GTD (geometrical theory of diffraction). The results are expressed the GTD form and various coefficients for the determination of edge-excited rays and surface ray fields are extracted. It is concluded that these coefficients can be used for the determination of diffracted rays and surface ray fields excited by apertures on arbitrarily curved surfaces. These coefficients are not valid in the transition regions, but they reveal the effect of surface curvature on the diffraction phenomenon
Diffraction of a TM Whispering Gallery Mode by the Edge of a Nonperfectly Conducting Spherically Curved Sheet
Electromagnetic scattering is a function of the scatterer's material properties as well as its geometry. Therefore, it is necessary to examine the effect of the physical properties of a body on diffraction phenomena besides the geometrical properties. The aim here is to give a rigorous asymptotic solution for the diffraction of high-frequency electromagnetic fields by an edge on a spherically curved sheet having a particular impedance property. The solution is interpreted with the terminology of the geometrical theory of diffraction (GTD). Copyright © 1986 by The Institute of Electrical and Electronics Engineers, Inc
A simple computer program for microwave radio link performance analysis
A simple computer program is developed for system power budget analysis of microwave radio links. As known, such an analysis is very important in radio link network planning and optimization of the existing transmission networks. The performance of the program developed in this study is tested by applying it to Adana region and by comparing with measurement results
Scattering at the Junction Formed by a PEC Half-Plane and a Half-Plane with Anisotropic Conductivity
In this study, scattering of plane electromagnetic waves at the junction formed by a PEC half-plane and a half-plane with anisotropic conductivity is investigated. By using a Fourier transform technique, the problem is formulated into a matrix Wiener-Hopf system, and a rigorous solution is obtained. Also, to show the effect of planar physical discontinuity explicitly, four different special cases are considered where the problems are reduced into pairs of simultaneous Wiener-Hopf equations. They are decoupled via polynomial transformations and solved through the standard procedure. The diffracted fields are expressed in a form suitable for GTD applications
Transition boundary conditions for simulation of thin chiral slab
Approximate two-side boundary conditions are deduced for the simulation of a thin chiral slab. It is also shown that, even in the leading approximation, when the thickness of a slab tends to zero, the transition conditions depend on chirality parameters, which leads to the possibility of studying the influence of a chiral slab on the external field in many diffraction problems
Diffraction of an obliquely incident plane wave by a two-face impedance half plane: Wiener-Hopf approach
The problem of diffraction of plane electromagnetic waves at an imperfectly conducting half plane with different impedances on upper and lower faces for oblique (skew) incidence either leads to a Wiener-Hopf equation with a 4×4 Fourier symbol matrix for the tangential field components or to two formally decoupled Wiener-Hopf equations with 2×2 symbol matrices of the Daniele-Khrapkov form for the electric and magnetic field components perpendicular to the diffracting edge. The higher-order edge singularity of the normal field components leads to undetermined constants in the classical Wiener-Hopf solution that are used to eliminate `unphysical' leaky wave poles that appear in the final solution by the residue calculus technique. The interrelation between both formulations involves an analytic family of polynomial transformation matrices. Consideration of the range restriction of this mapping is shown to be equivalent to the pole elimination procedure
Reflection and refraction by an anisotropic metamaterial slab with diagonal anisotropy
IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, COMCAS 2015 --2 November 2015 through 4 November 2015 -- --In this paper reflection and refraction phenomena by anisotropic metamaterial slab is investigated. The incident wave is assumed as both TE and TM polarization. The slab is located inside the free space. The reflection and refraction coefficients are obtained for both transmission from free space to metamaterial and from metamaterial to free space. The geometric optic approach is used to calculate total field upper and lower region of the slab. The reflection coefficient is considered for second order reflection while refraction coefficient is for the first order transmission. The effect of sign of dielectric permittivity and permeability components are examined. © 2015 IEEE
Diffraction coefficient for a half-plane with anisotropic conductivity
The diffraction of obliquely incident plane waves by a half-plane having anisotropic conductivity is investigated. The half-plane is assumed to be perfectly conducting in one direction and to have finite conductivity in the transverse direction. The material of the half-plane is simulated by a resistive-type boundary condition with the resistivity being a constant tensor. By using the Fourier transform technique, the problem is formulated into a pair of simultaneous Wiener-Hopf equations which are decoupled by means of a polynomial transformation and then solved by standard techniques. © IEE, 1996