Yazar "Delihacioglu, Kemal" seçeneğine göre listele

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    Chiral Metamaterials with Strong and Dynamically Optical Activity
    (Ieee, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Sabah, Cumali; Delihacioglu, Kemal
    In this study, chiral metamaterial that creates strong optical activity and dynamical circular dichroism due to geometry of the structure (gammadion-bilayer cross-wires) is presented. It includes the gammadion with discontinuous bilayer cross wire patterned on opposite sides. The designed chiral metamaterial offers easier fabrication and more efficient result. Also, transmission and reflection coefficients, theta and chirality coefficient of the medium are independently analyzed. It provides strong and dynamical optical activity due to the high chirality. The experimental results match with the results of the numerical study.
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    Design of Polarization and Incident Angle Insensitive Dual-Band Metamaterial Absorber Based on Isotropic Resonator
    (Emw Publishing, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
    Polarization and incident angle independent metamaterial-based absorber (MA) which acts as a strong dual-band resonator is designed and constructed. Besides, a method to design single/dualband MA is presented in detail. The proposed model is based on isotropic ring resonator with gaps and octa-star strip (OSS) which allows maximization in the absorption because of the characteristic features of the structure. Reflection and absorption responses are obtained both numerically and experimentally and compared to each other. Two maxima in the absorption are experimentally obtained around 90% at 4.42 GHz for the first band and 99.7% at 5.62 GHz for the second band which are in good agreement with the numerical simulations (95.6% and 99.9%, respectively). The numerical studies verify that the dual-band MA can provide perfect absorption at wide angles of incidence for both transverse electric (T E) and transverse magnetic (TM) waves. The proposed model can easily be used in many potential application areas such as security systems, sensors, medical imaging technology.
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    Electromagnetic Energy Harvesting By Using Tunable Metamaterial Absorbers
    (Ieee, 2015) Bakir, Mehmet; Karaaslan, Muharrem; Dincer, Furkan; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
    In this study, electromagnetic (EM) energy harvesting by using metamaterial absorber is numerically explained. Operation frequency is 2.40 GHz since it is the industrical scientific and medical (ISM) band. This band is especially chosen due to most of the customer electronic devices are working in this band. Split ring resonator that have two splits on it used in this study, chip resistors are placed on these splits for wireless energy transfer to the devices. 83.6% efficient electromagnetic energy harvesting is theoretically realized.
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    Increasing Bandwidth in Antenna Applications By Using Chiral Metamaterials
    (Ieee, 2015) Dincer, Furkan; Karaaslan, Muharrem; Bakir, Mehmet; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
    Chiral metamaterials are such materials that cannot be found in the nature and show exotic properties as negative refraction index. One of the most important properties of chiral metamaterials is to show optical activity by changing the polarization of the electromagnetic wave. In this way, an electromagnetic wave can be directed and can be controlled. Furthermore, cross coupling is created between electric field and magnetic field in the chiral medium In this study, focusing gain and effects on the antenna applications are searched. Since chiral metamaterials have exotic properties, they have advantages in antennas, gain, bandwidth and designing small material dimensions. 1 GHz bandwidth is obtained in this study.
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    Low profile antenna radiation enhancement with novel electromagnetic band gap structures
    (Inst Engineering Technology-Iet, 2013) Karaaslan, Muharrem; Unal, Emin; Tetik, Erkan; Delihacioglu, Kemal; Karadag, Faruk; Dincer, Furkan
    The authors design, characterise and fabricate electromagnetic band gap (EBG) structure composed of three different scale planar rectangular mushrooms for low profile antenna applications. Proof of principle demonstration of surface wave minimisation is realised between three different bands depending on mushroom numbers in one unit cell and low profile antenna radiation pattern enhancement is observed by monitoring transmission changes of surface waves using both two different numerical methods and measurements. Three different scale rectangular mushrooms show significantly better performance and wider EBG than many other EBG systems for improved antenna applications such as bow-tie and logarithmically periodic antennas.
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    TRANSMISSION TUNNELING THROUGH THE MULTILAYER DOUBLE-NEGATIVE AND DOUBLE-POSITIVE SLABS
    (Emw Publishing, 2013) Sabah, Cumali; Tastan, Haci T.; Dincer, Furkan; Delihacioglu, Kemal; Karaaslan, Muharrem; Unal, Emin
    Transmission tunneling properties and frequency response of multilayer structure are theoretically presented by using transfer matrix method. The structure is composed of double-negative and double-positive slabs which is sandwiched between two semi-infinite free space regions. Double-negative layers are realized by using Lorenz and Drude medium parameters. The transmission characteristics of the proposed multilayer structure based on the constitutive parameters, dispersion, and loss are analyzed in detail. Finally, the computations of the transmittance for multilayer structure are presented in numerical results. It can be seen from the numerical results that the multilayer structure can be used to design efficient filters and sensors for several frequency regions.
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    Transmission tunneling through the periodic sequence of double-negative and double-positive layers
    (2013) Sabah, Cumali; Tugrul Tastan, H.; Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Delihacioglu, Kemal
    Transmission tunneling based on the frequency behavior of a multilayer structure comprised of double-positive (DPG) and double-negative (DNG) layers is investigated. The structure is sandwiched between two identical half-spaces. The DNG layers are analyzed using Lorentz and Drude medium. Effects of the permittivity and permeability changes on the transmission are also examined for lossless and lossy situations. Finally, the transmission characteristics for the proposed multilayer structure are presented numerically. It can be seen that the multilayer structure may be used to design efficient filters for different frequency ranges. © 2013 IEEE.
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    Zigzag metallic conductors as frequency selective surfaces
    (Inst Engineering Technology-Iet, 2013) Delihacioglu, Kemal; Sabah, Cumali; Karaaslan, Muharrem; Unal, Emin
    Reflection and transmission properties of a new type of frequency selective surface (FSS) made of zigzag metallic elements placed periodically on a dielectric substrate are investigated theoretically for arbitrary polarisation. The electric field integral equation technique with the subdomain overlapping piecewise sinusoidal basis functions are employed to compute the unknown current coefficients induced on the metallic elements. The zigzag FSS arrays act as a low-pass filter in S-(1-5 GHz), X-(8-12 GHz) and K-u-(12-18 GHz) bands. Owing to multiple resonances the zigzag FSS arrays can be used in multiband frequency applications. Between the resonances there exist transmission windows that allow full energy transfer. By removing the first and third arms, the power reflection coefficient of three-arm zigzag FSS is compared with a freestanding strip FSS, and it is compatible with the measured and calculated results found in the literature.