Browsing by Author "Pekmezci,A."

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Citation Count: 0
First and second order mur type ABCs for DNG media
(Applied Computational Electromagnetics Society (ACES), 2018) Pekmezci,A.; Topuz,E.; Sevgi,L.
Reflections from boundaries of the FDTD computational domain lead to inaccurate, even unstable codes when dealing with problems involving double negative (DNG) materials. Here, an efficient and simple algorithm is presented for terminating FDTD in DNG medium which is based on first and second order Mur’s absorbing boundary conditions (ABC). FDTD update equations for Mur’s ABC formulations are obtained from frequency domain one-way wave equations using piecewise linear recursive convolution (PLRC) method. Numerical examples are given both for 1D and 2D scenarios to demonstrate the validity and stability of the proposed Mur formulations, and its advantages over uniaxial perfectly matched layer (UPML) in reducing computational time and memory requirements. © ACES.
Citation Count: 4
Properties of metamaterial based electromagnetic absorbers and shields
(Institute of Electrical and Electronics Engineers Inc., 2019) Pekmezci,A.; Sevgi,L.
Metamaterials are widely investigated as nominates for absorbers and shields in Electromagnetic Compatibility (EMC) techniques. Due to the dispersive nature of artificially constructed metamaterials, permittivity and/or permeability can be negative at a certain band of frequency. Since the propagation constant has imaginary values in lossless SNG media, electromagnetic waves decay in these media and reflect at the surface. When the permittivity and permeability values are both negative, propagating waves are supported and impedance matching between a double negative (DNG) medium and air can be achieved. For this reason, single negative (SNG) materials can be used in electromagnetic shielding applications and DNG materials for realization of electromagnetic (EM) absorbers. Theoretical analysis of metamaterial (MTM) based electromagnetic absorbers and shields are investigated using S- parameter calculations, and properties are presented as a function of layer compositions and different dispersion parameters of medium permittivity and permeability values. The characteristics of EM absorber/shields are also observed when metamaterial layers are stacked on a metal plate. © 2019 IEEE.