Browsing by Author "AYDIN, Elif"
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Item A New RF and Microwave Engineering Course Enriched With Advanced Technologies(2010-02-08) AYDIN, Elif; ÇAĞILTAY, NergizIn this study, a curriculum model including recent developments and technologies in the Radio Frequency (RF) and Microwave Engineering field by using a blended approach is proposed. This study covers the description of the content of theoretical and hands on applications, the integration model of the technological tools into the proposed curriculum, and the instructional approaches used in the new course design. The main goal of the course is to prepare students for future professional careers in RF and Microwave Engineering by supporting them with new instructional technologies. The secondary goal of the course is to better prepare the students for the sequence of senior courses in the Electrical and Electronics Engineering program of Atilim University. The course is structured with a balance between theory and laboratory, including remote and in lab measurement experiments as well as modeling and designing microwave components by means of computer tools and design fabrication. The newly designed course is implemented at the Atilim University. The study also reports the first semester implementation.Item A REMOTE LABORATORY FOR TRAINING IN RADIO COMMUNICATIONS: ERRL(IEEE, 2007-08-10) KARA, Ali; AYDIN, Elif; ÖKTEM, Ruşen; ÇAĞILTAY, NergizThis paper presents, first, a short survey of remote laboratory initiatives in electrical and computer engineering, and then discusses design and development phases of remote laboratory environment on radio communications, the ERRL (European Remote Radio Laboratory). As being the first attempt in establishing of such a large scale remote laboratory on radio communications, ERRL enables access to high technology RF equipments and setups through the Internet. The software structure, target groups and experimental set ups of ERRL are shortly discussed. First attempts on implementation of pilot experiments are discussed.Item A WEB BASED TRAINING MODULE FOR TEACHING DIGITAL COMMUNICATIONS(2015-06-02) KARA, Ali; ERDEM, Cihangir; ÖZBEK, Mehmet Efe; ÇAĞILTAY, Nergiz; AYDIN, ElifAn interactive module which simulates a digital transmission link from one end to the other has been designed. Using the module, a user may enter a short audio/message signal using microphone of a PC, and then follows processes on the signal at each stage of the digital transmission link. The user can also analyze the signal at every stage of the link, and compare the performance of various modulation schemes used in the link, and finally may see how the audio signal is corrupted by noise in the transmission link. In this way, from source point to destination point of the signal, the user may study various stages such as analog to digital conversion, analysis of effects of Gaussian noise on the message signal.Item AN EXPERIMENTAL STUDY ON NEAR GROUND RADIO PROPAGATION AT 900 MHZ(2022-01-21) BİLGİÇ, BURCU; KARA, Ali; AYDIN, ElifThe aim of this study is to analyze outdoor radio signal propagation according to experimental results. This thesis includes empirical data gathered from outdoor links on suburban and urban areas in Ankara. Path loss measurements at sub GHz are presented in five different outdoor environments. Path loss measurements were taken at different receiver and transmitter antenna heights. Furthermore, curve fittings arose from measurements over Line of Sight (LOS) and Non-Line of Sight (NLOS) links in outdoor environments are provided. This study clarifies the efficient usage of wireless devices in different outdoor links. This thesis provides cataloging about different antenna heights and different terrain path loss modeling and creating formulas by using curve fitting. A new model involving antenna height effects and terrain effects on path loss is presented. Also, previous literature models are compared with the presented models.Item An Indoor Navigation Aid Designed for Visually Impaired People(2008 34th Annual Conference of IEEE Industrial Electronics, 2008-08-09) ÖKTEM, Ruşen; AYDIN, Elif; ÇAĞILTAY, NergizThis work introduces the hardware architecture and general principles of a portable indoor navigation system for guiding visually impaired people. It operates through wireless communication between a compact hardware interface unit carried by the user, a central processing unit and an active RFID unit. The RFID unit collects signals as regard to the position of the user, the central system processes those signals to estimate the position of the user and proposes a route and direction for the user to follow, whereas hardware interface unit provides interaction. The orienteering of the user is obtained by a tactile compass.Item COMPARISONS OF COMPUTER-BASED PROPAGATION MODELS WITH EXPERIMENTAL DATA COLLECTED IN AN URBAN AREA AT 1800 MHz(2017-09-06) ACAR, Tarık; AYDIN, ElifNowadays a lot of models are set for the efficient and economic usage of frequency band which is a limited source. In this thesis, propagation models, developed and accepted in literature for this purpose, were studied. These are Free Space Path Loss (Fspl) + RMD (Epstein-Peterson), COST-HATA and COST-WI models. The district chosen for the model application has an irregular structure style. In the application of Free Space Path Loss (Fspl) + RMD (Epstein-Peterson), RTV Plan software is used; the other models were applied by calculations. In order to compare the success of the models, electric field strength measurements were taken in the chosen district (Mustafa Kemal Mahallesi-ANKARA), firstly at the random coordinate and secondly coordinates tracking on a single line. As a conclusion, measured values were compared with the results which were taken from the mentioned models with graphical presentations and the most appropriate model is tried be found and as another aim of the thesis study, a correction factor was generated as a modification for COST – HATA propagation model.Item Design and development of a remote and virtual environment for experimental training in Electrical and Electronics Engineering(2010 9th International Conference on Information Technology Based Higher Education and Training (ITHET), 2010-05-09) KARA, Ali; AYDIN, Elif; ÖZBEK, Mehme Efe; ÇAĞILTAY, NergizEuropean 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 and 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.Item DESIGN AND FABRICATION OF MINIATURIZED MICROSTRIP ANTENNAS AT 900 MHZ FOR INDUSTRIAL REMOTE CONTROLLERS(2022-02-14) Yılmaz, Vadi Su; KARA, Ali; AYDIN, ElifThis thesis explores the efficiency of miniaturization techniques for sub-GHz band remote control applications through simulations and measurements. First, the theory of microstrip antenna is studied and introduced at the beginning of the thesis. For the design process, a finite element method based simulation tool is used, multiple patches are designed accordingly. The miniaturization techniques are applied on the designed antennas. The antennas that satisfy the desired criteria are produced. The necessary measurements are subsequently made on the fabricated antennas, validity of the techniques is discussed. The effects of the box in which the antenna to be placed were examined as most of such antennas are enclosed by plastic boxes. Finally, a polyamide box with appropriate size was fabricated, and the designed antenna was placed inside the box and the measurements were conducted. The measurement results show that the designed antenna provides resonance at the targeted license-free band with appropriate size for industrial remote controllers.Item DESIGN OF MULTIBAND MICROSTRIP ANTENNAS(2022-02-28) GEBREEL, NADA F .SAAD; AYDIN, ElifMulti-band antenna has received great attention in wireless communication systems due to its pattern and polarization. Its capability of varying its operating frequency enables us to accommodate more than one service by using the same antenna. There is an increasing demand for lower-cost reconfigurable antennas that can be easily integrated. This thesis discusses the designs of multi-band antenna in which the designs are divided into parts. The first design is characterized by four patches without slot and with slot connected to the feed line of 2.4GHz, 3.1 GHz and 4.2 GHz. The design with the slot was the result of manufacturing a mismatch with the HFSS program. The frequency resonance was converted from 4.2 GHz to 3.1 GHz with errors of 0.07 and 0.16. The second design is divided into multi-band antenna designs in which we utilize a coaxial probe feed. We worked on the latest manufacturing design which contains two frequencies, namely 1.6 GHz and 3.6 GHz. In this thesis, We simulated and fabricated all the designed antennas. Measurement results were similar to the simulation results.Item DESIGN OF SMALL DUAL BAND SLOT ANTENNA(2017-01-07) Bubraig, Mabroka; AYDIN, ElifIn telecommunication, a micro-strip antenna (i.e., a printed antenna) usually means an antenna fabricated utilizing microstrip methods on a printed circuit board (PCB), with a continuous metal layer attached to the inverse side of the substrate which forms a ground plane. They are for the most part utilized at microwave frequencies. Microstrip antennas have turned out to be extremely mainstream in recent decades due to their thin planar profile which can be incorporated into the surfaces of customer items, aircraft, and missiles; their simplicity of fabrication using printed circuit techniques; the simplicity of integrating the antenna on the same board with the rest of the circuit, and the possibility of adding active devices such as microwave integrated circuits to the antenna itself to make active antennas. Antennas cover a wide range of applications in different areas, such as mobile communication, satellite navigation, internet services, automobiles, and radars. In this thesis, we simulated and fabricated small dual band slot antenna with a small size and good outcomes. The design parameters of the antenna used the transmission line model, and HFSS electromagnetic software was used for the simulation process.Item DESIGN OF VARIOUS MULTIBAND SLOT ANTENNAS(2022-02-28) MAHMOUD, WAFA MUSTAFA LAMIN; AYDIN, ElifIn these days, microstrip antennas cover a wide range of application in various areas, such as internet services, mobile communication, and satellite navigation. Microstrip antenna consists of two metal layers and a substrate. In the two metal layers, the top layer is called the patch and the bottom layer is called the ground. Between the patch and the ground there is the substrate layer which has a certain dielectric constant and thickness. The goal of this work is presenting a way of getting multi-band antennas for Wi-Fi devices and Wireless Communication System. These bands of frequency cover the standard IEEE 802.11b/g (2.4-2.485GHz) and IEEE 802.11a (5.15- 5.35GHz) for WLAN applications and 2.5 GHz (2.5-2.69GHZ), 3.5 GHz (3.3- 3.8GHz) and 5 GHz (5.25-5.85GHz) for Wi-MAX applications. We have used two different designs using program of software HFSS that has been used for simulation process. The multiband slot antennas have been simulated and manufactured by using two types of feeds. Firstly, the design of the antenna used the microstrip feed line and then we used the coplanar (CPW-Fed). Multi-band microstrip antennas were designed and simulated in terms of the return loss (S11) and the gain. These designs were fabricated and their return loss were measured and compared with the simulation results.Item Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field(Optimization of Electrical and Electronic Equipment, 2008-08-04) AYDIN, Cansu Çiğdem; ÖZYURT, Erdem; AYDIN, Elif; ÇAĞILTAY, Nergiz; ÖZBEK, Efe; ALPARSLAN, CerenIn 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.Item Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field(IEEE, 2008-05-24) AYDIN, Cansu Çiğdem; ÖZYURT, E.; AYDIN, Elif; ÇAĞILTAY, Nergiz; ÖZBEK, Mehmet Efe; ALPARSLAN, Ceren; KARA, AliIn 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.Item How to Teach Usage of Equipments in a Remote Laboratory(IEEE, 2007-08-10) ALPARSLAN, Nimet Ceren; ÇAĞILTAY, Nergiz; ÖZEN, Mustafa; AYDIN, ElifEuropean Remote Radio Laboratory (ERRL) is an e learning project for students, teachers and technicians of the universities who will use the very important devices of this laboratory remotely. These devices are very expensive to buy and can be broken easily while they have been using by the people who does not really know how to use them professionally. As a solution we have developed an e-learning system which aims to support the ERRL learners while studying on how to use equipments in the system. The system is developed according to the electronic performance support systems (EPSS) approach. An EPSS is a computer-based, well structured system which improves the performance of individuals. It is an electronic infrastructure that contains, stores and distributes personal (individual) or corporate knowledge to enable people to reach necessary levels of performance in the fastest possible time and with minimum teaching support of other people. This paper discusses how the content for such a system is developed and how this content is interactively used in the EPSS platform. The technical details of the developed EPSS are also discussed in this study. We believe that this paper will help instructional system designers for designing different alternatives to improve learners’ performance.Item Maintenance, sustainability and extendibility in virtual and remote laboratories(Social and Behavioral Sciences, 2011-08-10) KARA, Ali; ÖZBEK, Mehmet Efe; ÇAĞILTAY, Nergiz; AYDIN, ElifThis study presents discussions on sustainability of Virtual and Remote Laboratories (VRL), and provides challenges toward maintenance of VRLs. Technical and pedagogical issues in extension and sustenance of VRLs are discussed with the experiences of the authors gained in the development of a VRL system, European Remote Radio Laboratory (ERRL) platform. Moreover, the study presents actions to be taken in sustenance plan and expendability of VRL system with the advances in Information and Communication Technologies (ICT) and educational technologies along with the needs of educators and learners in formal education.Item OPTIMAL EXCLUSION ZONE ESTIMATION FOR CO-EXISTENCE OF GEOSTATIONARY AND NON-GEOSTATIONARY SATELLITE NETWORKS(2022-06-20) ÖZTÜRK, Faik; AYDIN, Elif; KARA, AliIn this thesis, the co-existence downlink interference from a typical Low Earth Orbit (LEO) constellation to earth stations of Geostationary Earth Orbit (GEO) satellites is analysed by performing minimization of Exclusion Zone (EZ) on the equatorial region. Using the Genetic Algorithm (GA), a multi-objective optimization problem (MOP) is formulated for non-dominant solutions set based on Exclusive Angle (EA) minimization and bandwidth utilization of the LEO communication link. At transmission bit rates of 100 Mbps and 200 Mbps, it is shown that the EA can be reduced up to % 21.3 and % 19.6, respectively, when compared to the initial anchor point. For the LEO communication system, the proposed optimal operational setting minimizes interference risk to the GEO satellite system as well as ensuring Quality of Service (QoS). Additionally, analysis and comparative evaluation of interference mitigation methods for coexisting Non-Geostationary Earth (NGEO) and Geostationary Earth (GEO) systems are discussed. Afterwards, the quantitative performance assessment of Spatial Isolation (SI), Power Control (PC), and Spatial Isolation-Based Link Adaptation (SILA) methodologies is performed. When compared to SI and PC techniques, the SILA technique utilizes the EA methodology more effectively. In various operating settings, the EA can be reduced up to % 8 for 100 Mbps and % 8.5 for 200 Mbps transmission bit rates when the PC method and the SILA method are combined. The performance assessment presented in this study may assist the satellite operator or decision-maker in determining the suitable mitigation strategy to apply in the event of co-existence interference.Item Principles for the Design of a Remote Laboratory: A Case Study on ERRL(IEEE, 2010-04-13) ÇAĞILTAY, Nergiz; AYDIN, Elif; KARA, AliRemote laboratories are getting very popular in engineering education programs. However, there are not many studies addressing the requirements and design issues of such laboratories. This paper discusses the results of a study of the requirements for developing a remote Radio Frequency (RF) laboratory for university students. This study draws on the perspectives of the students at the university, department of electrical engineering. The results are based on a research study established by 111 engineering students from France, Germany, Romania and Turkey. It investigates how students would like to use the technical content of a state of the art RF laboratory. The result of this study is also compared with the previous outcomes showing perspectives of the other learner groups of such laboratories; engineers and technicians in the technical colleges on the Radio Frequency (RF) domain. Considering the outcomes developed so far, some principles that need to be considered while designing and developing such a laboratory have been proposed. As a case study the proposed principles are implemented in a remote laboratory project. In this paper, the details of user requirements of such laboratories, the proposed principles and the implementation examples are all provided and discussed. Primarily, the general aim of this study is to guide remote laboratory platform developers towards the most effective design of their platforms.Item RADAR CROSS SECTION MEASUREMENT OF VARIOUS OBJECTS WITH 77-81 GHZ AUTOMOTIVE RADAR AND ASSESSMENT OF RADAR CROSS SECTION SIMULATION TOOLS(2022-12-19) SEZGİN, Deniz; AYDIN, Elif; KARA, AliIn this thesis, two of the most widely used computational EM methods which are being used for RCS prediction have been explained and compared. The methods involved in this comparison are Electric Field Integral Equation (EFIE) with Method of Moments (MoM) solution and Shooting and Bouncing Rays (SBR), which is a hybrid method consists of the combination of PO and GO. First of all, background informa tion about classical theory of electromagnetism and Radar Cross Section (RCS) and also the connection between them were presented. Then theoretical concepts were given for IE and SBR methods since this comparison also includes theoretical knowledge. Three targets were used in the measurements so that these methods could be compared with each other experimentally. RCS measurement were performed with a 77-81 GHz Commercial Off-The-Shelf (COTS) Frequency Modulated Continuous Wave (FMCW) radar system. In accordance with measurements, simulations were also performed at 77 GHz with both SBR and EFIE methods using two different commercial tools. Good agreement was found between measurement and simulation results, also it was observed that depending on the task both methods have various advantages over themselves.Item Remote laboratory development as an action research: A case study(2012-06-11) ÇAĞILTAY, Nergiz; TOKDEMİR, Gül; AYDIN, Elif; KARA, AliThis work presents a case study about how action research (AR) has been conducted in developing a real-life educational system. An explanation is given of the modified implementation of the classical AR methodology, based on the requirements of a remote laboratory system developed for the vocational training of students in higher education. This study reports a successful implementation of AR stages which established for the development process of a remote laboratory system along with the design of several research questions explored in each step of the system development process. It is believed that the outcomes of the study will help AR implementers to organize their research objectives, more appropriately, by addressing the organizational problems. The results of this study are also expected to guide the AR implementers to better integrate their research in solving domain specific practical problems.Item Requirements for Remote RF Laboratory Applications: An Educators’ Perspective(IEEE TRANSACTIONS ON EDUCATION, 2009-02-10) ÇAĞILTAY, Nergiz; AYDIN, Elif; ÖKTEM, Ruşen; KARA, Ali; ALEXANDRU, Marian; REINER, BodoThis paper discusses the results of a study of the requirements for developing a remote RF laboratory. This study draws on the perspectives of educators in university electrical engineering departments and in technical colleges, on the teaching of the radio frequency (RF) domain. The study investigates how these educators would like the technical content of a state of the art RF laboratory to be designed. As far as the authors know, no publication exists in the literature that investigates the requirements and needs of remote laboratories in that particular field. The outcomes of this work are expected to guide remote laboratory platform developers towards the most effective design of their platforms. The analysis of the results showed that educators would like the technical content of the laboratory to cover basic communication techniques, microwave circuits and devices, antennas and propagation, RF technology, and radio system design aspects of modern telecommunication systems. They would therefore like the laboratory instrumentation to be designed to that end. The educators also reported the need for advanced experimental setups which require expensive RF measurement devices. The discrepancy between university and technical college views was also considered in this paper.