WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653

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Institution Author: search.filters.institutionAuthor.Eyyuboglu, Halil T.Subject: search.filters.subject.Random Phase Screen

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Correction of Amplitude Distortions for Truncated Bessel Beam and Ser Estimation for 4ask
    (Taylor & Francis Ltd, 2016) Eyyuboglu, Halil T.
    We apply amplitude corrections to a truncated Bessel beam that has propagated through turbulent atmosphere modelled by random phase screens. These corrections are realized via transmitting an unmodulated beam in parallel to the one carrying the 4 amplitude shift keying (ASK) modulated message signal. On the receiver side, the amplitude corrections are obtained by dividing the intensity of the unmodulated beam by its free space equivalence. The corrections are then used to restore the amplitude distortions of the beam carrying the 4ASK modulated message signal and in the determination of decision boundaries for the received 4ASK symbols. The success of the system is visually inspected by comparing the received intensity profiles before and after the application of corrections. Furthermore, simulation analysis of symbol error rate (SER) is made, where the proposed set-up is found to be quite insensitive to wavelength difference between the unmodulated and modulated beams. On the other hand, the difference in the structure constant values of these two beams seems to have profound effect on system performance.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 17
    Scintillation Analysis of Hypergeometric Gaussian Beam Via Phase Screen Method
    (Elsevier, 2013) Eyyuboglu, Halil T.
    We give a scintillation treatment of hypergeometric Gaussian beams via the use of random phase screens. In particular, we analyse the on-axis, point-like and aperture averaged power scintillation characteristics of this beam that cannot be undertaken easily by analytic means. Within the range of examined source and propagation parameters, our evaluations show that there will be less scintillation, with increasing hollowness at small source sizes and zero topological charge. At larger source sizes or topological charges, this is reversed and decreasing hollowness will reduce scintillation. More or less the same trend is observed for aperture averaging such that at small source sizes and zero topological charge, increased hollowness will result in lower scintillation. At larger source size and topological charges, there will be a transition from the case of smaller values of hollowness giving rise to less scintillation at smaller aperture openings to the case of larger values of hollowness giving rise to less scintillation at larger aperture openings. In general nonzero topological charges will produces more scintillations, both in on-axis and aperture averaged cases. (C) 2013 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 30
    Citation - Scopus: 31
    Estimation of Aperture Averaged Scintillations in Weak Turbulence Regime for Annular, Sinusoidal and Hyperbolic Gaussian Beams Using Random Phase Screen
    (Elsevier Sci Ltd, 2013) Eyyuboglu, Halil T.
    Using the random phase screen method, aperture averaged scintillations for annular, sinusoidal and hyperbolic Gaussian beams are estimated. Prior to this estimation, the designed random phase screen setup is tested against the known results of the existing literature from the aspects of receiver intensity distribution, point-like scintillation index and aperture averaged scintillation of spherical and Gaussian beam waves. Having obtained satisfactory results, we then proceed to estimate aperture averaged scintillations for annular, sinusoidal and hyperbolic Gaussian beams. Our findings indicate that at a fixed aperture radius of 5 cm, sine Gaussian beam exhibits the highest scintillation, annular Gaussian beam has on the other hand has the lowest scintillations. When examined against varying aperture sizes, the scintillation ordering of beams does not change. Furthermore, although larger aperture sizes achieve substantial scintillation reductions, the rate of reductions gradually become smaller. (C) 2013 Elsevier Ltd. All rights reserved.