T. Sengor

Imaging of perfect conducting bodies by surface currents

Explicit expressions for the scattering of rotational symmetric high-frequency fields by a perfect conducting spherical sheet are obtained by surface currents induced on the cap. The results explain the contribution of surface currents to the scattered field and provide a method of obtaining the configurations of scatterers. The results can be used to describe an object by measurements at different points and check them with each other and analytical results.<<ETX>>

Electromagnetically equivalent dynamic model of seismic and atmospheric and ionospheric conjoined network of Turkey: The State Space Approach

This research concerns itself with modeling the seismicity-related geo-data as the self-optimization process of an electromagnetically equivalent device and developing a less accurate but fast model. The electromagnetically equivalent device model is extended as considering the whole Earth like a complete system. The crustal structures are considered as a complex network of distributed circuits involving slot antenna arrays, open waveguides, cavities, transmission strip lines, attenuators, frequency converters, dividers, couplings in the electromagnetically equivalent device model of the complete system of Earth (EEDMCSE). The variations at the geo-data taken at any port of the EEDMCSE give some functional relationships on the electromagnetic characteristics of the distributed complex network explained above. The approach is applied to Marmara and Aegean Regions of Anatolia.

Properties of inflective nano wires

The wave phenomena around inflection points are studied from a new point of view in order to coordinate inflective shapes analytically. The inflective coordinate systems are used to compute the exact solutions. The differential equations obtained using these recently introduced coordinate systems are solved by extending the usual separation method. These extensions bring out new, special functions and series, and the achieved results give the exact meaning of physics related with inflection points. In addition, the electromagnetic wave is calculated around inflection point. The approach is extended to the nano-scale.

Determination of the Behavior of Moving Human Body from the Scattered Field Data by using FDTD Method

This paper is a study on obtaining the necessary data for a possible design of an electronic system, which is used to give an output related to the behavior and goal of a moving human body. It is intended to obtain the characteristics of scattered field from several classified movement; i.e., normal, disquieted, and/or suspicious, in a closed three-dimensional region; i.e., a warehouse, which is under control. The problem is modeled with an inverse scattering approach. The time domain solutions related with electromagnetic waves scattered from human body moving with different behaviors are obtained by FDTD method

Waves in time and frequency dependable anisotropic cold plasma

This paper is a study about the frequency dependence and time varying characteristics in anisotropic materials. The perspective of the work includes convenient transformations for waves in dispersive and anisotropic materials and considers most types of such environments. The solution is obtained with the aid of tensor formalism. The cold plasma is modeled according to the introduced approach. The application of the method is given for a time varying and frequency dependent; i.e., TVFD cold plasma

Field of a circular loop near a symmetrical spherical cap

The field of a thin circular loop antenna symmetrically placed near a conducting spherical cap is computed. The total field is expressed in terms of three modal expansions in three different regions. Most of the unknown coefficients are obtained analytically. Some are solved numerically by using point matching. The same problem is also solved numerically by the Method of Moments, where the surface of the cap is approximated by planar triangular patches. Computed results obtained by both methods are in excellent agreement.

Well posed inversion mechanisms

This paper is a study of topological direct and inverse scattering. We discuss an exact and compact inversion method. The aim is to image the bodies with one to one correspondence. For this purpose we study the surface waves travelling on 3D curved surfaces with several singularities and extend some of the topological approaches. We construct the rules of topological diffraction. Those rules construct the law of topological diffraction (LTD). Multiple diffractions and near field calculations are taken into consideration. Approaches based on surface theory give the extraction of the physical mechanisms. Those extractions are used to obtain the field distribution. Following this the law of topological inversion (LTI) is obtained and constructed. With those rules we construct a well-posed inversion method, that is, the physical and surface theory of inverse scattering (PASTIS).

The exact computational solution approach by integral representation with an application to radiation characteristics of aperture antennas

A treatise of a new computational approach was constructed in this paper. The extraction mechanism is focused on the exact evaluations of radiated field by integral representations. The approach of integral representations gives an incomplete set of equations, however; this difficulty was passed by extending boundary conditions with a matching algorithm through integral representations. The equations are solved with a scenario managing algorithm by iterative reconfigurations of radiated field. The method is explained with the radiation problem of circular aperture by illustrations. The approach is suitable for optimization purposes of antenna design.

Necessary and sufficient conditions of exact target sensing

An exact method for imaging perfectly conducting bodies by means of high-frequency scattered field data is determined. A surface wave traveling on a three-dimensional curved body is treated. The explicit contributions of various diffraction phenomena to surface current are used to obtain the method. The method for exactly determining the configurations of convex bodies is given by results which explain the contribution of surface currents to the scattered field. The uniqueness condition for the solution of the inverse problem is obtained.<<ETX>>

High frequency radar cross section prediction

The essentials of a method developed to obtain the cross section of perfectly conducting targets by considering the surface current components induced on the bodies is presented. This approach treats the surface traveling wave phenomenon, allowing it to be included in RCS (radar cross section) computations for complex objects.<<ETX>>