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    Hybrid neural network optimization for feed point determination in antenna design
    (CEUR-WS, 2018) Ozkaya U.; Seyfi L.
    In this paper, coaxially feed rectangular microstrip antenna is designed for WIFI communication in accordance with IEEE 802.11a standard between 5.15 GHz and 5.725 GHz. Feeding position of coaxial probe significantly affected antenna characteristics. Optimum feeding point should be selected in 2-D patch plane on the purpose of better antenna characteristics. The model is used to solve the optimization problem. It has three input variables which are antenna parameters as resonance frequency, bandwidth and return loss; on the otherhand, two output such as x and y coordinates of feeding position. Also, error function is updated by proposed artificial intelligence algorithms. Unlike conventional methods, contemporary artificial intelligent algorithms have been proposed for the antenna design. Genetic Algorithm (GA), Spider Monkey Optimization (SMO) and Grey Wolf Optimizer (GWO) are preferred for optimization. According to comparison of these results, optimal antenna for WIFI Protocol is designed. Copyright held by the author(s).
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    SAR values in a homogenous human head model
    (2011) Seyfi L.; YaldIz E.
    The purpose of this chapter is to present how to determine and reduce specific absorption rate (SAR) on mobile phone user. Both experimental measurement technique and a numerical computing method are expressed here. Furthermore, an application on reduction of SAR value induced in human head is carried out with numerical computing. Mobile phone working at 900 MHz frequency shielded with copper is considered in order to furnish reduction of SAR in simulations which are conducted to calculate the maximum SAR values in Matlab programming language using two dimensional (2D) Finite Difference Time Domain (FDTD) method. Calculations are separately made for both 1 g and 10 g. Head model structure is assumed uniform. © 2011 Springer Science+Business Media B.V.