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Conference Object Citation - Scopus: 2Design and Fabrication of Ka Band Circular Horn Antenna;(2012) Danaci,S.; Gürtekin,E.; Özyurt,E.; Kara,A.In this paper, design and fabrication of a circular horn antenna is presented. The antenna is designed for experimental use at Ka band. The design process includes feeding structure for coaxial line and geometrical parameters of the antenna. The bandwidth of the antenna is measured as 2.25GHz, (S 11 ≤-10dB) which satisfies the requirements of targeted experimental study. A reference monopole is also designed for the measurements of antenna parameters. Antenna radiation pattern is measured with the reference monopole antenna using a VNA (S12) instead of typical signal generator/spectrum analyzer pair. Accuracy of antenna parameters along with the errors made in fabrication process is also discussed in the paper. © 2012 IEEE.Conference Object Citation - Scopus: 20Design and Development of a Remote and Virtual Environment for Experimental Training in Electrical and Electronics Engineering(2010) Kara,A.; Aydin,E.; Ozbek,M.E.; Cagiltay,N.European Remote Radio Laboratory (ERRL) has been developed by the support of European Commission. It intends to provide remote access to high cost devices remotely, and perform experiments in radio frequency (RF), communications and microwave domains of Electrical ad Electronics Engineering. The system has been operational for two years, and been integrated into curriculum of some courses. In this work, the hardware and software structures of the system are presented. Then, experimental content and the motivations in the design of the system are discussed. ©2010 IEEE.Article Citation - Scopus: 11Modelling of Shadowing Loss Due To Huge Non-Polygonal Structures in Urban Radio Propagation(Electromagnetics Academy, 2008) Kara,A.; Yazgan,E.Ray tracing algorithms rely on two dimensional or three dimensional database. They use ray optical techniques referred to as the uniform theory of diffraction (UTD) using building database given as polygons. Building geometries can also be modelled as having non-planar geometries, and this would be important in modeling of shadowing loss due to curved structures in urban radio propagation. To demonstrate modelling of buildings as non-polygonal geometries, a particular building composition involving 3D cruved geometries is chosen, and shadowing loss for this building composition is studied via UTD ray tracing. Building structure considered in this study involves main canonical shapes of non-planar geometries including cone, cylinder and sphere. Single and multiple interaction of surface diffractions, effect of creeping waves are taken into consideration in the analysis. © 2008, Electromagnetics Academy.Conference Object Citation - Scopus: 4Distance Laboratory Applications Errl: a Study on Radio Communication in Electronic Field(2008) Aydin,C.Ç.; Türkmen,G.; Özyurt,E.; Aydm,E.U.; Çaǧiltay,N.E.; Özbek,M.E.; Kara,A.In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes important everyday, the indispensable elements of teaching and education, laboratories must be reachable via remote connection. Consequently, the education that is going to be given to the students will be more flexible with respect to place and time constraints and students can reach laboratory facilities at any time and anywhere not only in lectures and practical hours. In this study, European Remote Radio Laboratory (ERRL) which is a distance remote Radio Frequency (RF) laboratory designed for electrical-electronics students, is described generally. The software architecture, infrastructure and experiment that can be done with a remote connection have been described.Article Citation - Scopus: 9Multipath Exploitation in Emitter Localization for Irregular Terrains(Czech Technical University, 2019) Dalveren,Y.; Kara,A.Electronic Support Measures (ESM) systems have many operational challenges while locating radar emitter's position around irregular terrains such as islands due to multipath scattering. To overcome these challenges, this paper addresses exploiting multipath scattering in passive localization of radar emitters around irregular terrains. The idea is based on the use of multipath scattered signals as virtual sensor through Geographical Information System (GIS). In this way, it is presented that single receiver (ESM receiver) passive localization can be achieved for radar emitters. The study is initiated with estimating candidate multipath scattering centers over irregular terrain. To do this, ESM receivers' Angle of Arrival (AOA) and Time of Arrival (TOA) information are required for directly received radar pulses along with multipath scattered pulses. The problem then turns out to be multiple-sensor localization problem for which Time Difference of Arrival (TDOA)-based techniques can easily be applied. However, there is high degree of uncertainty in location of candidate multipath scattering centers as the multipath scattering involves diffuse components over irregular terrain. Apparently, this causes large localization errors in TDOA. To reduce this error, a reliability based weighting method is proposed. Simulation results regarding with a simplified 3D model are also presented. © 2019 RADIOENGINEERING.Conference Object Citation - Scopus: 2Miniaturized 2.4 Ghz Antenna Design for Uav Communication Link;(Institute of Electrical and Electronics Engineers Inc., 2020) Yilmaz,V.S.; Kara,A.; Aydin,E.In 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. © 2020 IEEE.Conference Object Pilot Remote Experiment in the Errl: Measurement of Scattering Parameters(2007) Özen,M.; Aydin,E.U.; Kara,A.A remote laboratory platform enables the learners to access physical instruments at distant location and to perform experiments remotely via the Internet. This paper focuses on a pilot remote laboratory experiment on measurement of scattering parameters (s parameters) by using vector network analyzer (VNA) in the ERRL (European Remote Radio Laboratory) platform. The results of the pilot experiment are presented, and discussed shortly. © 2007 IEEE.Conference Object Citation - Scopus: 1Development of a low cost radio controller for Tele operation systems: Crane controller design as an industry sponsored undergraduate research(2013) Kaynaköz,G.; Daǧdeviren,B.; Kapusuz,K.Y.; Kara,A.This study presents some of the design and development stages of a radio control system for dense interference environments. All design and development stages were conducted by undergraduate students, with an undergraduate research project sponsored by a local company. The study starts with an overview of the system including choice of main components and modules. Then, it discusses the design stages of the system from analog to digital conversion to driving circuit of the targeted mechanical system (crane), and provides some preliminary results and conclusions. One of the design criteria in the project was minimization of the cost and size, and the preliminary results have shown that the prototype could compete with many commercial equivalents.Conference Object Citation - Scopus: 1Analysis of Measurement Instrumentation Delay in Modular Experimental Radar at C Band(Institute of Electrical and Electronics Engineers Inc., 2018) Abdulrazigh,M.Y.A.; Uzundurukan,E.; Kara,A.Unlike 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. © 2018 IEEE.Conference Object Citation - Scopus: 7Software Technologies, Architectures and Interoperability in Remote Laboratories(2010) Özbek,M.E.; Kara,A.; Ataş,M.A remote laboratory aims to provide access to remote lab equipment over the internet. The design and development of the client software is subject to various requirements. In this paper we discuss these requirements and propose solutions. Implementations are demonstrated for some remote experiments developed in the ERRL project. An XML format for experimental results is proposed as an attempt towards standardization of remote laboratory interfaces and enhancing the interoperability of diverse remote laboratory applications. ©2010 IEEE.
