Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Subject: search.filters.subject.Metamaterial

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  • Article
    Citation - WoS: 34
    Citation - Scopus: 37
    Metamaterial antenna designs for a 5.8-GHz Doppler radar
    (IEEE, 2020) Yılmaz, Hasan Önder; Yaman, Fatih
    The aim of this paper is to investigate applicability and the effectiveness of the metamaterial-based antennas for a 5.8-GHz Doppler radar. Thus, a double negative index metamaterial structure is designed as a transmitter antenna and a near-zero index medium is integrated with a patch antenna for the receiver. Significant improvements in bandwidth for the transmitter, slight improvements in gain and in directivity for the receiver, and typically size reduction for both antennas are obtained. It is shown that return loss, radiation pattern, and gain measurement results of the newly designed antennas agree well with the simulations for a desired frequency band. The last part of the study is devoted to express the adaptation of the antennas for a low-power radar system whose aim is to reconstruct the velocity of the human, indoor as well as behind the wall, from the shift in the received frequency. The accuracy of the velocity measurements and field test results of the radar with the metamaterial antennas are reported.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 13
    Fourcross Shaped Metamaterial Filters Fabricated From High Temperature Superconducting Ybco and Au Thin Films for Terahertz Waves
    (IOP Publishing Ltd., 2017) Demirhan, Yasemin; Alaboz, Hakan; Nebioğlu, Mehmet Ali; Mulla, B.; Akkaya, M.; Altan, Hakan; Sabah, Cumali; Özyüzer, Lütfi
    In this study, we present a new, unique fourcross shaped metamaterial terahertz (THz) filter fabricated from both gold thin films and YBa2Cu3O7-δ high Tc superconducting thin films. A commercial electromagnetic simulation software, CST Microwave Studio, is used to design and optimize the metamaterial filter structures. The proposed fourcross shaped rectangular filter structure consists of periodic metallic rings where strip lines are located at the sides of the ring. Fourcross metamaterial filters are fabricated by using e-beam lithography and ion beam exhing techniques. Terahertz time-domain spectroscopy measurements validated the design predictions for both the center frequencies and bandwidths of the resonances due to the fourcross structures. The resonance switching of the transmission spectra was investigated by lowering the temperature below the critical transition temperature. This resonance switching effect is not observed in filters made up of metals. This novel fourcross rectangular resonator with a temperature-dependent resonance behavior holds great potential for active, tunable and low loss THz devices for imaging, sensing, and detection applications.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    An Indium Tin Oxide Metasurface Filter for Terahertz Applications: Design, Fabrication, and Characterization
    (World Scientific Publishing Co. Pte Ltd, 2017) Nebioğlu, Mehmet Ali; Takan, Taylan; Altan, Hakan; Demirhan, Yasemin; Alaboz, Hakan; Özyüzer, Lütfi; Sabah, Cumali
    In this paper, using a cross-shaped complementary Indium Tin Oxide (ITO)-based metasurface design, the transmission of THz radiation is shown to be filtered within the 3 dB level from maximum in the frequency range of interest (333 GHz). Various metasurface structures primarily composed of cross-shaped openings with a 400 micron unit cell size are patterned on top of 1750 micron thick fused silica substrates. They are patterned using UV lithography methods after the films were grown using DC sputtering. The fabricated structures were characterized using Terahertz Time Domain Spectroscopy (THz-TDS) measurement technique. The measured transmission agrees well with the simulation of the structure for four different samples with different geometries. These results suggest that metasurface and/or metamaterial patterns based on ITO in visibly transparent media can be utilized for filtering of frequencies in the long wavelength spectrum. These types of filters can be very useful in the near future for THz communication and security applications. ©