Browsing by Author "Kalender, Gizem"

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Application of dielectric resonator based metamaterial in waveguide coupler
(Institute of Electrical and Electronics Engineers Inc., 2016) Gizem Kalender; Emine Yeşim Zoral; Mustafa Seçmen; Zoral, E. Yesim; Secmen, Mustafa; Kalender, Gizem
In this study an implementation of the metamaterial structure is used in a waveguide directional coupler. For this purpose a four-hole waveguide directional coupler in X-band is designed. Then the block of dielectric-resonator array is inserted between isolation port and holes of the coupler and the performances of the coupler with and without dielectric resonators are compared in terms of the coupling and isolation. The obtained results show that the coupler with dielectric resonators significantly improves the coupling and isolation performances at a new operation frequency band at which the traditional coupler does not work. Therefore the metamaterial structure attains multi-band characteristics to the coupler. Besides this new frequency band can be shifted by arranging the distance between the dielectric resonators and holes. Finally it is also observed that the bandwidth of the new frequency band can be increased by using more dielectric resonators in the array. © 2017 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Effective Permittivity and Permeability of Dielectric Resonator Arrays in Rectangular Waveguide for Metamaterial Applications
(IEEE, 2015) Gizem Kalender; Mustafa Secmen; Yesim Zoral; Secmen, Mustafa; Zoral, Yesim; Kalender, Gizem
The study describes the effective permittivity and permeability calculation of dielectric resonator arrays embedded in a WR90 rectangular waveguide structure. The scattering parameters are extracted and verified with full-wave simulations and measurements within 8-14 GHz. Then the effective permittivity and permeability values are acquired with the retrieval method. The results reveal that the structure shows double negative (DNG) characteristics at some frequencies when the distance between resonators is close enough. Therefore the structure can be considered in the design of metamaterial applications.
Citation - WoS: 1
Citation - Scopus: 1
Metamaterial Characteristics of Dielectric Resonator Arrays in Rectangular Waveguide and Free space
(IEEE, 2015) Gizem Kalender; Mustafa Secmen; Emine Yesim Zoral; Zoral, Emine Yesim; Secmen, Mustafa; Kalender, Gizem
The study demonstrates the metamaterial characteristics of the arrays containing dielectric resonators by evaluating the permittivity and permeability coefficients of the array structures in rectangular waveguide and free space. For this purpose the array with two closely spaced dielectric resonators is setup and placed both in a rectangular waveguide and free space one by one. The scattering parameters in both structures are extracted with full-wave simulations (CST Microwave Studio) and supported with measurement results. Then the effective relative permittivity and permeability values are obtained with the deembedding technique and retrieval method. According to the results the structures show double negative (DNG) characteristics at some frequencies. Therefore the array with dielectric resonators is shown to have metamaterial characteristics. Besides the DNG frequencies of both (waveguide and free space) structures are found to be consistent to each other. This means that the metamaterial behaviour of the dielectric resonator array is highly insensitive to the wave excitation where TE10 and TEM modes are excited in rectangular waveguide and free space respectively.