Browsing by Author "Aydin, Elif"
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Article Citation Count: 1CALCULATION OF RESONANT FREQUENCIES OF A SHORTING PIN-LOADED ETMA WITH ANN(Wiley-blackwell, 2014) Can, Sultan; Aydın, Elif; Aydin, Elif; Department of Electrical & Electronics Engineering[No Abstract Available]Article Citation Count: 6Comparative assessment of electromagnetic simulation tools for use in microstrip antenna design: Experimental demonstrations(Wiley, 2019) Yılmaz, Vadi Su; Yilmaz, Vadi Su; Bilgin, Gülsima; Kara, Ali; Aydın, Elif; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringThis paper presents a better understanding of the use of finite integration techniques (FIT) and finite element method (FEM) in different types of microstrip antennas in order to determine which numerical method gives relatively more accurate results. Although the theoretical formulation based on Maxwell's equations of both FEM and FIT are approached from different aspects in the literature, there is still a lack of comparison of the same antenna type using different numerical methods employing FEM and FIT. Therefore, in this study, FEM and FIT were applied to two different types of microstrip antennas, and their simulation and experimental results was compared. For the first antenna demonstration, a multilayer structure was chosen to achieve one of the significant parameters. Then, a microstrip antenna with a compact structure was used in the second demonstration. Using these two antennas, the accuracy of FEM and FIT in different structures were compared and all simulated return loss and gain results were verified by the measured results. The experimental demonstrations show that FEM performs better for both types of microstrip antennas while FIT provides an adequate result for two-layer microstrip antennas.Article Citation Count: 8Computation and optimization of resonant frequency and input impedance of a coax-fed circular patch microstrip antenna(John Wiley & Sons inc, 2007) Aydın, Elif; Aydin, Elif; Yazgan, Erdem; Department of Electrical & Electronics EngineeringMicrostrip antennas are important elements of today's wireless communication networks. In their various applications, it is critical to provide wide hand operation around the resonant frequency providing good impedance match between the antenna element and the feed. In this study, new, simple, arid accurate computation of resonant frequency and input impedance of double-layered, coaxial fed circular disk microstrip antenna with air gap is performed. In the analysis, new effective radius and permittivity expressions are used in simple and modified form including modal effects. Then, a new approach is proposed to provide input impedance matching (it resonant frequency via the application of microgenetic algorithm for wide hand operation. The accuracy of theoretical calculations and impedance matching approach are presented for various,structural parameters and operational modes of the antenna. (C) 2007 Wiley Periodicals, Inc.Article Citation Count: 6Implementing consecutive project-based learning in an antenna and propagation course(Sage Publications Ltd, 2016) Aydın, Elif; Kalaycı, Elif; Department of Business; Department of Electrical & Electronics EngineeringIn this study, a 'consecutive-project-based learning' structure applied to the antennas and propagation course is introduced. The first project, carried out with the faculty of management, aims to familiarize the teams with the challenges of 'real life tender-like conditions'. In the following three projects, teams perform their assigned antenna projects. Each team researches the theoretical background, studies the main parameters of antennas and evaluates them. After designing, simulating, specifying the testing requirements of the antennas, each team makes one financial and one time budget. At the end of the term, each team makes a presentation to a jury. Finally, a questionnaire is conducted to evaluate the achievement of the outcomes. This paper focuses on the first two projects because they constitute the critical stages of the course as the first project enables inexperienced students to discover the issues they might face in a 'real world' project and draw lessons from that experience to be used in the more comprehensive following project. The first project's aim is to equip the inexperienced students with elementary knowledge on working in a team; paying attention to time, budget, project phases and people management issues so that they can use that knowledge in the second project, thus learning takes place as a product of consecutive projects. Statistical information on the students' academic performances is analyzed to observe if this course has improved their academic performance. The results indicate that 'consecutive-project-based learning' is an effective method in antennas and propagation course.Conference Object Citation Count: 17Maintenance, sustainability and extendibility in virtual and remote laboratories(Elsevier Science Bv, 2011) Kara, Ali; Özbek, Mehmet Efe; Aydın, Elif; Aydin, Elif; Çağıltay, Nergiz; Department of Electrical & Electronics Engineering; Software EngineeringThis 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. (C) 2011 Published by Elsevier Ltd.Article Citation Count: 4Miniaturised antenna at a sub-GHZ band for industrial remote controllers(inst Engineering Technology-iet, 2019) Yılmaz, Vadi Su; Bilgin, Gulsima; Bilgin, Gülsima; Aydın, Elif; Kara, Ali; Electrical-Electronics Engineering; Department of Electrical & Electronics EngineeringThis study presents the design and the fabrication of a miniaturised sub-GHz antenna for remote control applications. Miniaturisation techniques were examined to identify the most appropriate topology for sub-GHz band requirements. First, the design parameters of the antenna were determined, and then, a commercial electromagnetic simulation tool was used for the design and optimisation phases. Then, measurements of the fabricated antenna were undertaken. Parametric studies with several iterations were performed to achieve the best possible results. Second, the effects of the box in which the antenna could be placed were examined as most of such antennas are enclosed by plastic boxes. For this purpose, material properties of a typical industrial box available in the market were studied initially, and the most appropriate material of the box was used in simulations. 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 adequate size for industrial remote controllers.Article Citation Count: 0A Miniaturized Multi-layer Microstrip Antenna for Linear Wireless Sensor Network Monitoring Systems(Gazi Univ, 2022) Bilgin, Gülsima; Aydın, Elif; Kara, Ali; Aydin, Elif; Kara, Ali; Department of Electrical & Electronics EngineeringThis article presents a sub-GHz ISM band microstrip patch antenna based on the use of multilayer compact structure, which overcomes the shortcomings of typical microstrip antennas such as low gain and high resonant frequency. The antenna was simulated using an electromagnetic simulator, ANSYS HFSS, and fabricated on two different substrates: RT Duroid 5880 and FR4 epoxy with a compact size of 100 x 100 x 8 mm3 (0.29 lambda x 0.29 lambda x 0.02 lambda). The simulated results of the antenna were then compared with the measured ones, and the two were observed to have a reasonable agreement. The proposed antenna operates in the sub-GHz license-free ISM band (862-875 MHz), with a gain value of 2.92 dB. Two prototypes of the proposed antenna were fabricated and used in a Linear Wireless Sensor Networks (LWSNs) monitoring system. Results show that the proposed antenna is a good candidate for those types of LWSNs systems.Article Citation Count: 9Modified resonant frequency computation for tunable equilateral triangular microstrip patch(Ieice-inst Electronics information Communications Eng, 2010) Aydın, Elif; Can, Sultan; Department of Electrical & Electronics EngineeringIn this paper, a new closed form expression is developed to accurately estimate the resonant frequency of an equilateral triangular patch. The proposed computation is also extended to the two-layer structure in order to define the air-gap tuning effect on the resonant frequency. The theory established in this paper is compared with the experimental and theoretical results available in the literature. The results of this study show a considerable improvement achieved over the previous theories within very small percentage errors for almost all cases.Article Citation Count: 4NEURAL NETWORK BASED RESONANT FREQUENCY SOLVER FOR RECTANGULAR-SHAPED SHORTING PIN-LOADED ANTENNAS(Wiley, 2013) Can, Sultan; Aydın, Elif; Aydin, Elif; Department of Electrical & Electronics EngineeringThis study presents an artificial neural network (ANN) estimation of the operating frequencies of shorting pin-loaded rectangular microstrip patch antennas. A feed forward back propagation multilayer perceptron neural network structure is applied in the study. The results are compared with the ones in the literature and the FEM based simulation results. The results of the operating frequencies obtained by using this method are in very good agreement with the experimental results presented in the literature. Several antennas are also simulated by a finite element method based solver and these results are also compared with the results of the proposed neural network model. The average error of the lower frequency obtained by this study has a decrement of 2.025% when compared to the FEM based simulation software and for the upper frequency this difference is 6.835%. The effects of permittivity of the antenna, size of the dimensions of the rectangular patch, and the shorting pin position are also evaluated. In the light of the ANN model and the relations obtained two antennas in the same shape are produced and the results of these antennas are presented as well. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3025-3028, 2013Article Citation Count: 0A new model for indoor propagation prediction using genetic algorithm(Ieice-inst Electronics information Communications Eng, 2008) Aydın, Elif; Department of Electrical & Electronics EngineeringIn this study, a new, simple and accurate computation of the received signal strength (RSS) level for indoor environment is performed. The genetic algorithm (GA) approach is used for prediction of the RSS. The proposed model is formed on the knowledge of measurements without requiring any detail of the environment. The model provides a time efficient method to estimate RSS dynamically at any location in the test environment. The accuracy of the measurement results and the genetic algorithm approach are presented for three distinct transmitters located at different positions.Article Citation Count: 9A new RF and Microwave Engineering course enriched with advanced technologies(Wiley, 2012) Aydın, Elif; Çağıltay, Nergiz; Department of Electrical & Electronics Engineering; Software EngineeringIn 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. (C) 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 634645, 2012Article Citation Count: 9Operating frequency calculation of a shorting pin-loaded ETMA(Wiley-blackwell, 2012) Aydın, Elif; Can, Sultan; Department of Electrical & Electronics EngineeringThis article presents the calculation of upper and lower operating frequencies with the expressions of effective side length, effective permittivity, and correction factor to develop accurate lower and upper operating frequencies of a single feed, a shorting pin-loaded equilateral triangular patch, that is, analyzed through a cavity model. To insert permittivity and shorting pin position effects correction factor expressions are determined empirically for both upper and lower frequencies. The various positions of the shorting pin, substrate thickness and side length properties are considered by calculating both upper and lower frequencies. The results from this study are compared with research in the literature comprising results from both experimental and transmission line models. (C) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:14321435, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26838Article Citation Count: 29Requirements for Remote RF Laboratory Applications: An Educators' Perspective(Ieee-inst Electrical Electronics Engineers inc, 2009) Aydın, Elif; Kara, Ali; Oktem, Rusen; Çağıltay, Nergiz; Alexandru, Marian; Reiner, Bodo; Department of Electrical & Electronics Engineering; Software EngineeringThis 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.Article Citation Count: 10An RFID based indoor tracking method for navigating visually impaired people(Tubitak Scientific & Technological Research Council Turkey, 2010) Aydın, Elif; Aydin, Elif; Department of Electrical & Electronics EngineeringThis paper tackles the RFID based tracking problem in an obscured indoor environment. The proposed solution is an integral part of a navigation aid for guiding visually impaired people in a store. It uses RF signal strengths and is based on the Bayes Decision Theory. An observation vector is formed by received radio signal strength indication values, transmitted from three transmitters at distinct frequencies in the UHF band. The indoor area is divided into square grids, where each grid is considered as a class. The problem of tracking is expressed as classifying the observed radio signal strengths to the most likely class. A classification rule is formulated by incorporating a priori assumptions appropriate for the studied model. The proposed approach is tested in a laboratory environment. The results prove that the proposed approach is promising in tracking especially when the tracked person is guided by a system.Article Citation Count: 18Seven Principles of Instructional Content Design for a Remote Laboratory: A Case Study on ERRL(Ieee-inst Electrical Electronics Engineers inc, 2011) Ekin, Cansu Çiğdem; Aydin, Elif; Aydın, Elif; Kara, Ali; Alexandru, Marian; Çağıltay, Nergiz; Computer Engineering; Department of Electrical & Electronics Engineering; Software EngineeringThis paper discusses the results of a study of the requirements for developing a remote radio frequency (RF) laboratory for electrical engineering students. It investigates students' preferred usage of the technical content of a state-of-the-art RF laboratory. The results of this study are compared to previous findings, which dealt with other user groups (technicians in technical colleges and engineers in the RF domain). Based on the results of these analyses, seven essential principles for designing and developing such a laboratory were identified. As a case study, these principles were then implemented into a remote laboratory system. In this paper, the implementation examples are also provided and discussed. The primary aim of this study is to guide remote laboratory platform developers toward the most effective instructional design. This study also determined, from the remote laboratory system case study, what the requirements are of such a laboratory from the students' perspective.