Browsing by Subject "Singular integral equations"
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Item Open Access Analysis of a thin, penetrable, and nonuniformly loaded cylindrical reflector illuminated by a complex line source(Institution of Engineering and Technology, 2017) Oğuzer, T.; Kuyucuoglu, F.; Avgin, I.; Altıntaş, A.A thin, penetrable, and cylindrical reflector is illuminated by the incident field of a complex source point. The scattered field inside the reflector is not considered and its effect is modelled through a thin layer generalised boundary condition (GBC). The authors formulate the structure as an electromagnetic boundary value problem and two resultant coupled singular integral equation system of equations are solved by using regularisation techniques. The GBC provides us to simulate the thin layer better than the resistive model which is applicable only for very thin sheets. Hence, the more reliable data can be obtained for high-contrast and low-loss dielectric material. The scattering and absorption characteristics of the front-fed and offset reflectors are obtained depending on system parameters. Also, the effects of the edge loading are examined for both E- and Hpolarisations. The convergence and the accuracy of the formulation are verified in reasonable computational running time.Item Open Access Analysis of the elliptic-profile cylindrical reflector with a non-uniform resistivity using the complex source and dual-series approach: H-polarization case(Springer, 2013) Oğuzer, T.; Altintaş, A.; Nosich, A. I.An elliptic-profile reflector with varying resistivity is analyzed under the illumination by an H-polarized beam generated by a complex-source-point (CSP) feed. The emphasis is done on the focusing ability that is potentially important in the applications in the optical range related to the partially transparent mirrors. We formulate the corresponding electromagnetic boundary-value problem and derive a singular integral equation from the resistive-surface boundary conditions. This equation is treated with the aid of the regularization technique called Riemann Hilbert Problem approach, which inverts the stronger singular part analytically, and converted to an infinite-matrix equation of the Fredholm 2nd kind. The resulting numerical algorithm has guaranteed convergence. This type of solution provides more accurate and faster results compared to the known method of moments. In the computations, a CSP feed is placed into a more distant geometrical focus of the elliptic reflector, and the near-field values at the closer focus are plotted and discussed. Various far-field radiation patterns including those for the non-uniform resistive variation on the reflector are also presented.Item Open Access Test of accuracy of the generalized boundary conditions in the scattering by thin dielectric strips(IEEE, 2014-05) Nosich, A. I.; Shapoval, O. V.; Sukharevsky, Ilya O.; Altıntaş, AyhanThe two-dimensional (2D) scattering of the E and H-polarized plane electromagnetic waves by a free-standing thinner than the wavelength dielectric strip is considered numerically. Two methods are compared: singular integral equations (SIE) on the strip median line obtained from the generalized boundary conditions for a thin dielectric layer and Muller boundary integral equations (BIE) for arbitrarily thick strip. The comparison shows the domain of acceptable accuracy of approximate model derived for thin dielectric strips. © 2014 IEEE.Item Open Access Validity of generalized boundary conditions and singular integral equation method in the scattering of light by thin dielectric strips(IEEE, 2014) Shapoval O. V.; Sukharevsky, Ilya O.; Altıntaş, AyhanWe consider the two-dimensional (2D) scattering of a plane wave of light by a thin flat dielectric nanostrip. Empirical method of generalized boundary conditions and singular integral equations on the strip median line is compared with Muller boundary integral equations method that does not assume the strip thickness to be small. The conclusions are achieved about the validity of approximate models for thin dielectric strips.Item Open Access Wave scattering by one and many thin material strips: singular integral equations, Meshless Nystrom discretization, and periodicity caused resonances(IEEE, 2014) Shapoval, O. V.; Sukharevsky, Ilya. O.; Altıntaş, Ayhan; Sauleau, R.; Nosich, A. I.We consider the medial-line singular-integral equation technique for the analysis of the scattering by multiple thin material strips. Their discretization is performed using the Nystrom-type scheme that guarantees convergence. Numerical study of the scattering by periodic arrays of a few hundred or more strips reveals specific high-Q resonances caused by the periodicity.