Mehmet ERTUĞRUL

Article | 2021 | Waves in Random and Complex Media ( Published online: 22 Jul 2021 )

A feasible extraction procedure is proposed to retrieve the diagonal tensor elements of the permittivity and permeability, and the magnetoelectric coupling coefficient of Omega-type biansiotropic metamaterials (MMs). The procedure is based on the state transition matrix approach and uses non-iterative closed-form expressions between constitutive parameters and scattering (S-) parameters to achieve such determination using S-parameters for normal incidence and oblique incidence of TE and TM modes (a desirable feature from practical point of view). S-parameter simulations of a bianisotropic MM slab constructed by edge-coupled resonato . . .rs are performed using a 3D electromagnetic simulator program and used to validate the proposed procedure and compare its accuracy against previously developed extraction procedures. The effects of incidence angle, S-parameter More less

Mehmet ERTUĞRUL

Article | 2023 | Waves in Random and Complex Media ( Published online: 23 Jan 2023 )

Mathematical and numerical analyses have been performed to examine the close link between Fabry–Pérot resonance and natural-resonance frequencies. For the mathematical analysis, the conditions resulting in minimum magnitudes of reflection coefficients in frequency-domain are derived for air-backed and metal-backed low-loss non-dispersive (or weakly dispersive) dielectric samples with relative complex permittivity εr and thickness L for free-space wave propagation at normal incidence. The close relation between Fabry–Pérot resonance and natural-resonance frequencies is demonstrated for three different sample scenarios as (i) no-dispe . . .rsion and lossless case (εr=4.8−j0.0 and L = 50 mm), (ii) no-dispersion and low-loss case (εr=4.8−j0.01 and L = 50 mm), and (iii) weak-dispersion and low-loss case (εr=4.8−jσ/(ωε0) and L = 50 mm where σ is the conductivity of the sample and ω is the angular frequency). It is noted that operating frequency should be increased to observe late-time natural-resonance frequencies for a sample with smaller length or vice versa More less

Ercan ÇELİK

Article | 2022 | Waves in Random and Complex Media ( Published online: 08 Nov 2022 )

We study an optimal control problem for a Schrodinger-type equation that states the motion of a charged particle in a varying electromagnetic field. The objective functional is given by an integral criterion over boundary of domain. The solvability of considered optimal control problem is proved.