Now showing items 21-40 of 47

    • Gunn oscillations in GaN channels 

      Sevik, Cem; Bulutay, Ceyhun (IOP, 2004)
      Gallium nitride with its high negative differential mobility threshold is an appealing material for high power millimetre-wave oscillators as a Gunn diode. By means of extensive ensemble Monte Carlo simulations, the dynamics ...
    • Harmonic cantilevers for nanomechanical sensing of elastic properties 

      Şahin, O.; Yaralıoğlu, G.; Grow, R.; Zappe, S. F.; Atalar, Abdullah; Quate, C.; Solgaard, O. (IEEE, 2003-06)
      We present a micromachined scanning probe cantilever, in which a specific higher order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have demonstrated that ...
    • High-resolution imaging of elastic properties using harmonic cantilevers 

      Sahin, O.; Yaralioglu, G.; Grow, R.; Zappe, S. F.; Atalar, Abdullah; Quate, C.; Solgaard, O. (Elsevier, 2004)
      We present a micromachined scanning probe cantilever, in which a specific higher-order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have fabricated such ...
    • Hybrid model for probe-fed rectangular microstrip antennas with shorting pins 

      Mutlu, Selma; Aksun, M. İrşadi (IEEE, 2000)
      For a probe-fed microstrip antenna, it is quite common to employ the cavity model to find the field distribution under the patch and other electrical properties. Therefore, a multiport analysis technique based on the cavity ...
    • Improved performance of cMUT with nonuniform membranes 

      Şenlik, Muhammed N.; Olcum, Selim; Atalar, Abdullah (IEEE, 2005-09)
      When capacitive micromachined ultrasonic transducers are immersed in water, the bandwidth of the device is limited by the membrane's second resonance frequency. At this frequency no mechanical power to immersion medium can ...
    • Interaction between a cMUT cell and a liquid medium around the parallel resonance frequency 

      Şenlik, Muhammed N.; Atalar, Abdullah; Olçum, Selim (IEEE, 2007-10)
      In this paper, we present how a capacitive micromachined ultrasonic transducer (cMUT) couples to the immersion medium, based on an accurate parametric model. We show that the velocity of cMUT membrane can be written as a ...
    • Investigation of magnetic resonances for different split-ring resonator parameters and designs 

      Aydin, K.; Bulu, I.; Guven, K.; Kafesaki, M.; Soukoulis, C. M.; Özbay, Ekmel (Institute of Physics Publishing, 2005)
      We investigate the magnetic resonance of split-ring resonators (SRR) experimentally and numerically. The dependence of the geometrical parameters on the magnetic resonance frequency of SRR is studied. We further investigate ...
    • Laser-micromachined millimeter-wave photonic band-gap cavity structures 

      Özbay, Ekmel; Tuttle, G.; McCalmont, J. S.; Sigalas, M.; Biswas, R.; Soukoulis, C. M.; Ho, K. M. (American Institute of Physics, 1995)
      We have used laser-micromachined alumina substrates to build a three-dimensional photonic band-gap crystal. The rod-based structure has a three-dimensional full photonic band gap between 90 and 100 GHz. The high resistivity ...
    • Location and curvature estimation of spherical targets using multiple sonar time-of-flight measurements 

      Barshan, B. (Institute of Electrical and Electronics Engineers, 1999-12)
      A novel, flexible, three-dimensional multisensor sonar system is described to localize the center of a generalized spherical target and estimate its radius of curvature. Point, line, and planar targets are included as ...
    • Metamaterial Absorber Based Multifunctional Sensor Application 

      Ozer Z.; Mamedov, Amirullah; Özbay, Ekmel (Institute of Physics Publishing, 2017)
      In this study metamaterial based (MA) absorber sensor, integrated with an X-band waveguide, is numerically and experimentally suggested for important application including pressure, density sensing and marble type detecting ...
    • Metamaterial-based wireless RF-MEMS strain sensors 

      Melik, Rohat; Ünal, Emre; Perkgoz, Nihan Kosku; Puttlitz, C.; Demir, Hilmi Volkan (IEEE, 2010)
      Approximately 10% of the fractures do not heal properly because of the inability to monitor fracture healing. Standard radiography is not capable of discriminating whether bone healing is occurring normally or aberrantly. ...
    • Metamaterial-based wireless strain sensors 

      Melik, R.; Unal, E.; Perkgoz, N. K.; Puttlitz, C.; Demir, Hilmi Volkan (American Institute of Physics, 2009-07-07)
      We proposed and demonstrated metamaterial-based strain sensors that are highly sensitive to mechanical deformation. Their resonance frequency shift is correlated with the surface strain of our test material and the strain ...
    • Multi-gap individual and coupled split-ring resonator structures 

      Penciu, R.S.; Aydin, K.; Kafesaki, M.; Koschny Th.; Özbay, Ekmel; Economou, E.N.; Soukoulis, C.M. (Optical Society of American (OSA), 2008)
      We present a systematic numerical study, validated by accompanied experimental data, of individual and coupled split ring resonators (SRRs) of a single rectangular ring with one, two and four gaps. We discuss the behavior ...
    • Multilevel PO algorithm for non-uniform triangulations 

      Manyas, Alp; Gürel, Levent (ESA Publications, 2006)
      Fast physical optics (FPO) algorithm provides a speedup for computing the physical optics (PO) integral over complex bodies for a range of aspect angles and frequencies. In this paper, this algorithm is further developed ...
    • Nested metamaterials for wireless strain sensing 

      Melik, R.; Unal, E.; Perkgoz, N. K.; Santoni, B.; Kamstock, D.; Puttlitz, C.; Demir, Hilmi Volkan (IEEE, 2009-12-28)
      We designed, fabricated, and characterized metamaterial-based RF-microelectromechanical system (RF-MEMS) strain sensors that incorporate multiple split ring resonators (SRRs) in a compact nested architecture to measure ...
    • A new effective side length expression obtained using a modified tabu search algorithm for the resonant frequency of a triangular microstrip antenna 

      Karaboğa, D.; Güney, K.; Kaplan, A.; Akdağli, A. (John Wiley & Sons, 1998)
      A new, very simple curve-fitting expression for the effective side length is presented for the resonant frequency of triangular microstrip antennas. It is obtained using a modified tabu search algorithm, and is useful for ...
    • Optimization and tunability of deep subwavelength resonators for metamaterial applications: complete enhanced transmission through a subwavelength aperture 

      Alici, K.B.; Bilotti F.; Vegni L.; Özbay, Ekmel (Optical Society of American (OSA), 2009)
      In the present work, we studied particle candidates for metamaterial applications, especially in terms of their electrical size and resonance strength. The analyzed particles can be easily produced via planar fabrication ...
    • Optimizing CMUT geometry for high power 

      Yamaner F.Y.; Olcum, Selim; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2010)
      Capacitive micromachined ultrasonic transducers (CMUTs) have demonstratedvarious advantages over piezoelectric transducers. However, current CMUT designsproduce low output pressures with high harmonic distortions. Optimizing ...
    • Photonic band gap in the triangular lattice of Bose-Einstein-condensate vortices 

      Taşgin, M. E.; Müstecaplioǧlu Ö. E.; Oktel, M. Ö. (2007)
      We investigate the photonic bands of an atomic Bose-Einstein condensate with a triangular vortex lattice. Index contrast between the vortex cores and the bulk of the condensate is achieved through the enhancement of the ...
    • Reflection properties of metallic photonic crystals 

      Temelkuran, B.; Özbay, Ekmel; Sigalas, M.; Tuttle, G.; Soukoulis, C. M.; Ho, K. M. (1998)
      We measured reflection-magnitude and reflection-phase properties of metallic photonic crystals. The experimental results are in good agreement with the theoretical calculations. We converted the reflection-phase information ...