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  • Küçük Resim Yok
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    A programmable digital metasurface structure designed using ANN technique
    (Taylor & Francis Ltd, 2023) Altintarla, Gizem; Unal, Emin; Altintas, Olcay; Gencoglan, Duygu N.; Colak, Sule; Nazeri, Amir H.; Alkurt, Fatih Ozkan
    In this paper, an 8-bit programmable digital metasurface is designed in the operating frequency range from 4 to 7 GHz. A monopole antenna operating at 5 GHz is characterised by using a metasurface structure as the ground plane. Various combinations of the metasurface structure are examined by altering the state of each unit-cell between `ON (1)' and `OFF (0)' in the coding matrix. The purpose of the 8-bit programmable digital metasurface is to control the electromagnetic wave effectively in the frequency range of interest. Dynamically controllable metasurface structure is utilised to change the unit cells' configurations. In addition, the proposed adjustable metasurface is capable to control the monopole antenna directivity, gain and main lobe magnitude, efficiently. According to various via conditions, different metasurface-based antenna parameters such as return loss (S11), radiation pattern, directivity and surface current distribution are investigated by means of the commercial numerical simulation software, CST microwave studio. Employing the simulation results of the metasurface-based antennas, the artificial neural network (ANN) data set is obtained. 128 activation conditions are trained and tested by Levenberg Marquart learning algorithm. During the ANN procedure, MATLAB is used to obtain accurate results by changing the rate of test and training data set.
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    Öğe
    A study on electronically controllable beamforming monopole antenna for telecommunication applications
    (Taylor & Francis Ltd, 2023) Alkurt, Fatih Ozkan; Unal, Emin; Palandoken, Merih; Altintarla, Gizem; Abdulkarim, Yadgar I.; Hasar, Ugur Cem; Karaaslan, Muharrem
    The design, analysis, and prototyping of an electronically controllable beamforming monopole antenna (ECBMA), which could be a good candidate for ceil-mounted wireless telecommunication systems, are reported. The proposed ECBMA targeting the 2.45 GHz center frequency is based on the 'on-off' ground reflectors, which are connected to the main ground layer by twelve RF switches to implement digital logic states. There are twelve ground reflectors symmetrically positioned over azimuthal angle direction in the ECBMA structure controlled by RF switches and a microcontroller unit, thus resulting in a pattern change when the states of the switches change logically. The designed ECBMA has the following three main features. First, it has a good and stable reflection coefficient (S11) characteristic at the 2.45 GHz centre frequency. Second, it has a wideband characteristic between 2.15 and 2.85 GHz (700 MHz operational bandwidth). Third, it has the capability to create single, double, or multi-beam characteristics (multi-purpose) which is a highly desired feature in many modern wireless communication systems mainly suitable for indoor applications. The prototype of our ECBMA is fabricated, and the performance analysis is investigated experimentally and S11 and radiation characteristics have good performance and are in good agreement with the simulation results. The proposed ECBMA has a good candidate for wireless telecommunication purposes such as WLAN, ISM, Wi-Fi, Bluetooth and other RF peripherals like indoor applications.