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Conference Object Citation - WoS: 2Citation - Scopus: 3Design Considerations for Sub-Ghz Multilayer Microstrip Antenna for Near Ground Communication Links in Rural Areas(Ieee, 2017) Bilgin, Gulsima; Yilmaz, Vadi Su; Aydin, Elif; Kara, Ali; Department of Electrical & Electronics Engineering; Electrical-Electronics EngineeringThis paper presents some preliminary results of design and development of sub-GHz multilayer microstip antenna for use in near ground communication applications. In design stage of the antenna, iterative approach was applied. Firstly, a two layer microstrip antenna design process is presented. Next, the corners of the patch were cut, and a vertical wall on all sides of the antenna were introduced. In this way, both the size and resonant freqeuncy can be tuned. Moreover, as an application specific requirement, it is intended to embed this antenna into a metal box in order to protect it from man-made and natural environmental effects. This was also studied, and effects of the embedding ground on the antenna characteristics were examined. It is shown that the designed antenna provides -27dB resturn loss, and 7.3dB peak gain at 915MHz with the dimension of 150x200x13mm. Some preliminary measurements have proven the simulations.Conference Object Citation - WoS: 2New Wavelet-Based Features for the Recognition of Jittered and Stagger Pri Modulation Types(Ieee, 2015) Gencol, Kenan; Kara, Ali; At, NurayIn dense electronic warfare environments, numerous emitters can be active simultaneously and an interleaved stream of pulses in natural time of arrival order is received by the Electronic Support Measures (ESM) receiver. It is the task of the ESM system to de-interleave this mixed pulse sequence and thus to identify the surrounding threatening emitters. In this processing, pulse repetition interval (PRI) modulation recognition has a significant role due to the fact that it can reveal the hidden patterns inside pulse repetition intervals and thus help identify the emission source and its functional purpose. In this paper, we propose new wavelet-based features for the recognition of jittered and stagger PRI modulation types. The recognition of these types are heavily based on histogram features. Experimental results show that the proposed feature set have very high recognition rates and outperform histogram based methods.Conference Object Citation - WoS: 1An Industry Sponsored Undergraduate Research (ur) Experience: Preliminary Study on Fulfillment of Program Outcomes and Industry Requirements(Ieee, 2014) Kapusuz, Kamil Yavuz; Kara, AliThis study presents educational results of an industry sponsored undergraduate research (UR) project. The aim of the study is to show how such project works contribute to students in acquiring qualifications or skills necessary by the industry, and abilities regarding with program outcomes of accreditation organisations. The study is based on quantitative (surveys) and qualitative (self descriptions) data collected from senior students who worked in 9 months UR project sponsored by a company in Radio frequency (RF) and Communications domain. The preliminary results showed that an industry sponsored undergraduate research project may serve to both short term (industry requirements) and longer term (program outcomes) expectations in undergraduate curriculum of engineering departments.Conference Object Design of Low-Cost Modular Rf Front End for Rf Fingerprinting of Bluetooth Signals(Ieee, 2017) Uzundurukan, Emre; Ali, Aysha M.; Kara, AliFor RF fingerprinting of wireless devices, data acquisition has a critical role. Because of this, highly sophisticated devices arc used for data capturing or acquisition. In this paper, design of a RF receiver front end with modular components is presented. This design contains filtering and down conversion processing of Bluetooth signals for cellular phones. Moreover, AWR VSS and MATLAB have been used for simulating the down converter circuit. With this simulation, effects of components that used in the design on recorded signal have been observed. In this work in progress paper, only high SNR conditions are considered.Conference Object Miniaturized 2.4 Ghz Antenna Design for Uav Communication Link(Ieee, 2020) Yilmaz, Vadi Su; Kara, Ali; Aydin, ElifIn many communications applications, unlike conventional antennas, lightweight, flexible, small antennas that can adapt to mechanical and industrial constraints are required. In this study, the results of antenna design operating at 2.4 GHz are presented for use in Unmanned Aerial Vehicle (UAV) tele command links. In the parametric and optimization studies carried out on the antenna, it is aimed to increase the gain while keeping the size as small as possible. The requirements of the industry, such as light, aesthetics, miniature and high gain aspects of the antenna were targeted in the design process. Finally, an antenna of 55.2x88 mm size and 7dB gain was achieved using commercial electromagnetic design tools. The designed antenna become satisfying industrial requirements with these features.Conference Object Citation - WoS: 2Citation - Scopus: 3An Experimental Study on the Influence of Human Movement in Indoor Radio Channel at 28ghz(Ieee, 2021) Benzaghta, Mohamed; Coruk, Remziye Busra; Yalcinkaya, Bengisu; Kara, AliHuman activities around the communication link in an indoor environment have a significant impact on millimeter-wave (mmWave) communication systems, which are used for the new generation of communication networks (5G). Therefore, it is essential to evaluate short range indoor links from the link blockage point of view. This paper presents the propagation measurements in the presence of human activity, for a short range indoor office environment communication link at 28 GHz. During the experimental measurements, the human activity of three and six persons were observed for three different antenna height combinations. The human blockage (shadowing effect) is characterized in terms of the shadowing event duration, temporal fading, as well as overall attenuation. The results reported by this experimental study is believed to be vital in designing future mmWave communication systems that can overcome the deep fades caused by human blockage in short indoor communication links. Yet, this paper constitutes a part of an ongoing research study, further detailed results will be foreseen to present the precise effect of human movements around the propagation link at 28GHz.Conference Object Citation - WoS: 1Analysis of Measurement Instrumentation Delay in Modular Experimental Radar at C Band(Ieee, 2018) Abdulrazigh, Mahfoud Y. A.; Uzundurukan, Emre; Kara, AliUnlike pulsed radars, Frequency-Modulated Continuous Wave (FMCW) radar emits continuously very low power levels with the same signal to noise ratio (SNR) of an equivalent pulsed radar. FMCW can measure range and speed of the target. In modular design of such radar, time delay is experienced due to modular components such as low-noise amplifiers (LNA), antennas and, especially, cables. This time delay causes frequency shifts in the measured beat frequency resulting a range measurement error. Therefore, this time delay has to be studied for accuracy of measurements. In this study, experimental results of range measurement errors of a FMCW radar operating at C band are presented. Considering time delay of modular components, a range error of approximately 0.1m was obtained within a range of 10m.Conference Object Citation - WoS: 3Comparative Analysis of Tdoa-Based Localization Methods in the Presence of Sensor Position Errors(Ieee, 2017) Dalveren, Yaser; Kara, AliIt is widely known that localization of emitters can be efficiently achieved by time difference of arrival (TDOA) techniques in a multiple sensor system. Several studies have been proposed in the literature to improve the localization accuracy of TDOA techniques. Among these, very few of them have considered the error in the sensor positions although the accuracy of localization is very sensitive to sensor position errors. In this study, existing TDOA-based localization methods in the presence of sensor position errors are briefly discussed, and then they are comparatively analyzed for specific scenarios. To this end, simulations are performed to compare the localization accuracy of the methods, specifically, with high level of sensor positional errors. It is intended to decide an efficient and robust estimator to be used for an ongoing research on passive localization of radar emitters in dense scattering environments.Conference Object Citation - WoS: 1A Modular Fmcw Radar Rf Front End Design:simulation and Implementation(Ieee, 2014) Dagdeviren, Birkan; Kapusuz, Kamil Yavuz; Kara, AliIn this work, simulations and preliminary measurement results of an S-band FMCW radar is presented. A commercial simulation tool (AWR-VSS) has been used at system level design stage of the radar. The simulation tool provides all functions regarding with transmitter, target and receiving blocks, and it finally feeds echo signals to the digital processing block implemented in MATLAB. The target range and velocity have been derived for simple target scenario in MATLAB. Then, a modular RF front end of the radar has been designed using commercial of the shelf (COTS) components. The radar system has been proved to be working in indoor environment using measurement equipment. Moreover, design of horn antennas for transmitting and reception blocks have been demonstrated Real time signal processing functions will be developed at the next stage.Conference Object Uhf Propagation Measurements in Heavy Industry(Ieee, 2016) Tutuncu, Seyma; Kara, AliEstimating in-factory radio signal propagation characteristics accurately provides robust communication link configuration in these areas. In line with this purpose, this work here provides propagation path loss measurement results carried out in three heavy industrial environments at 315, 434, 870 ve 915 MHz frequency bands.
