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Öğe Comparison of Free Space Measurement Using a Vector Network Analyzer and Low-Cost-Type THz-TDS Measurement Methods Between 75 and 325 GHz(Springer, 2017) Ozturk, Turgut; Morikawa, Osamu; Unal, Ilhami; Uluer, IhsanSpecifications of two measurement systems, free space measurement using a vector network analyzer and low-cost-type terahertz time-domain spectroscopy using a multimode laser diode, have been compared in the frequency region of millimeter/sub-THz waves. In the comparison, accuracy, cost, measurement time, calculation time, etc. were considered. Four samples (Rexolite, RO3003, Ultralam 3850HT-design, and L1000HF) were selected for the comparison of the specifications of the two methods. The acquired data was used to compute the complex permittivity of measured materials. The extracted results by free space measurement agreed well to the ones obtained by low-cost-type terahertz time-domain spectroscopy. This result proves free space measurement that can be assessed as a new method of material characterization in the sub-THz region successfully worked. Furthermore, free space measurement was proved to be suitable for a measurement in a narrow frequency range. On the other hand, low-cost-type terahertz time-domain spectroscopy has features not only low cost but also measurement capability in wide frequency range.Öğe Development of extraction techniques for dielectric constant from free-space measured S-parameters between 50 and 170 GHz(Springer, 2017) Ozturk, Turgut; Elhawil, Amna; Uluer, Ihsan; Guneser, Muhammet TahirThis paper is a comprehensive study on Newton-Raphson technique used in millimeter wave frequencies for material characterization. Various algorithms are used for extracting the complex permittivity of a material from measured S-parameters. Efficiency of the methods depends on the initial guess and the accuracy of measured S-parameters for each thickness and frequency band. In this paper, we suggest the initial-value estimation method that helps to estimate a proper value for starting the algorithm. Moreover, an alternative extraction process is modelled that does not require new measured S-parameters or extracting process for each frequency band and thickness with a composed database. The estimation process is conducted partially as V (50-75 GHz), W (75-110 GHz), and D (110-170 GHz) frequency bands.Öğe Development of Measurement and Extraction Technique of Complex Permittivity Using Transmission Parameter S 21 for Millimeter Wave Frequencies(Springer, 2017) Ozturk, Turgut; Hudlicka, Martin; Uluer, IhsanThis study provides an overview of measured S-parameters and its processing to extract the dielectric properties of materials such as Teflon, PMMA, and PVC which are preferred for materials characterization process. In addition, a correction model is presented for transmission parameter (S (21)) to obtain the dielectric constant with high accuracy. A non-destructive and non-contact free space measurement method has been used to measure S-parameters of thin samples in the low THz frequency range. S-parameters are measured in free space by vector network analyzer supported with two frequency extenders. Additionally, the parabolic mirrors are used to collimate the generated beam in wide frequency range. Furthermore, a standard filter process is performed to remove the undesired ripples in signal using singular spectrum analyzer before the implementation of extraction process. Newton-Raphson extraction technique is used to extract the material complex permittivity as a function of the frequency in Y-band (325-500 GHz).Öğe Effects of Electrical Properties on Determining Materials for Power Generation Enhancement in TEG Modules(Springer, 2019) Ozturk, Turgut; Kilinc, Enes; Uysal, Fatih; Celik, Erdal; Kurt, HuseyinThis study aimed to increase the energy efficiency of thermoelectric generators designed by considering the electrical properties of p- and n-type semiconductor materials for reducing the costs associated with the experiments, errors, and long production processes. Accordingly, the estimation of the energy amount to be produced by the thermoelectric materials was achieved by different doping elements using three different parameters such as skin-depth, electrical conductivity and dielectric constant. Additionally, the findings were supported by experimental results. In contrast to the conventionally used black-box type approach and estimation methods, an inference was obtained on the actual values of the materials.Öğe Estimation of Complex Permittivity for Solids and Liquids at sub-THz Frequency Range(Ieee, 2018) Ozturk, TurgutIn this paper, two different extraction techniques are presented to estimate the complex permittivity of materials with high level accuracy. The performances of presented models are discussed to illustrate their potential for obtaining the dielectric properties and composing a database which will is used to identify the unknown materials easily. Furthermore, the composed data base can be used to classify the liquids as safe or unsafe. Moreover, the relationship of between S-parameters and permittivity are showed using estimating methods. The proposed model gives better results as well as analytical and numerical extraction techniques.Öğe Experimental Studies Based on Classification of Explosive and Non-Explosive Liquids(Ieee, 2017) Ozturk, Turgut; Sayiniti, Aysun; Unal, IlhamiNowadays, since the explosive liquids can easily be obtained by mixing simple substances, the electromagnetic methods developed for safety purposes have gained acceleration. In this study; liquids which may be explosive with chemical explosion, combustion and combination, as well as, non-explosive liquids which may be found inside baggages in airports are used to measure electromagnetic responses ranging from 1-50 GHz and complex dielectric permeability coefficients are calculated with commercial software. Explosive and non-explosive liquids are classified a with the help of three different algorithms such as PLS, PCA and K-Means.Öğe Extracting the dielectric constant of materials using ABC-based ANNs and NRW algorithms(Taylor & Francis Ltd, 2016) Ozturk, Turgut; Elhawil, Amna; Dugenci, Muharrem; Unal, Ilhami; Uluer, IhsanFive different Nicolson-Ross-Weir (NRW) extracting techniques are used to extract the dielectric constants of Teflon, Rexolite, Glass (borosilicate and soda-lime), Paper, and Ultralam 3850HT from S-parameters. The results of these extraction techniques are used to train the Artificial Neural Networks. In order to improve the accuracy of the results, the weights of ANNs are calculated using artificial bee colony estimation method. The results are compared with that obtained using NRW, Newton-Raphson, and genetic algorithm. The obtained results indicate that the proposed model gives good extracted parameters as compared with the previously published results.Öğe The Importance of Mode Spacing of Multimode Laser Diode to Generate the THz Signal(Ieee, 2018) Ozturk, Turgut; Guneser, Muhammet TahirWhen examined Time Domain Spectroscopy system which uses multimode laser diodes (MLD) for THz signal generation, the importance of mode spacing of MLD is remarkable. When the previous studies are compared with each other, it has been determined that the wavelength distance between each mode of MLD should be small. In this context, the optical spectrum analyzer (OSA), which examine the mode spacing, can be used to predict the success of the MLD in the THz signal generation. Thus, in order to be able to choose the most suitable MLD (cheap and compact) to be used in a TDS system, the mode spacing analysis will be sufficed.Öğe Improving the Energy Management of a Solar Electric Vehicle(Univ Suceava, Fac Electrical Eng, 2015) Guneser, Muhammet Tahir; Erdil, Erzat; Cernat, Mihai; Ozturk, TurgutA solar electric vehicle (SEV) is an electric vehicle (EV) with onboard photovoltaic cells charging a set of batteries for extended driving range. This study aimed to improve the energy management system of a SEV, called YILDIZ, using a fuzzy logic control system (FLC). A MATLAB based simulation model of three basic components of a solar car: solar cell modules, batteries and motor drive system was performed. An original FLC was developed. For proving its applicability, the performances of the SEV were tested by simulation, in accordance with the standard test drive cycle ECE-15. The characteristics obtained with the original Proportional Integral Fuzzy Logic Control (PI-FLC) were compared with those obtained with a classical Proportional Integral (PI) controller. Using the designed model, we calculated the range of YILDIZ with and without PV feeding which gave us an opportunity to study and compare both SEV and EV models on real race-track situation. Then the optimum speed, at any time, which enabled the vehicle to reach a chosen destination as quickly as possible, while fully using the available energy, was calculated. Proposed solutions tested on YILDIZ. Results of simulations were compared with YILDIZ run on the Formula-G race track in Izmit, Turkey.Öğe An Induction Motor Design for Urban Use Electric Vehicle(Ieee, 2016) Guneser, Muhammet Tahir; Dalcali, Adem; Ozturk, Turgut; Ocak, Cemil; Cernat, MihaiBecause of fossil fuel shortage and its damages on environment, electric vehicles (EV) are going to be more popular in science and car industry as well. So, EV's take an opportunity to spread over the traffic finally. But battery, which is the main energy supplier of the motor, has disadvantages as big volume and weight. Scientists try to enhance energy densities, ranges and quicken charging. All of research results force us to drive EV in a loop, close to charging stations for near future. So EV's should be designed by considering urban road and speed conditions as well. In this survey, we designed a new two pole 7,5 kW induction motor for a certain electric vehicle, which was designed to use urban drive. We considered urban traffic rules and conditions, while designing the motor. We simulated and verified analytical and finite element analysis of the designed induction motor. We also modelled and simulated the EV with the induction motor on MATLAB to observe control performance of field oriented control (FOC) on several urban use scenarios. According to our results, EV with designed motor can be realized and controlled.Öğe Influence of Rotor Slot Structure at Starting Torque and Efficiency on Urban Use EV Motor(Ieee, 2019) Guneser, Hammet Tahir; Dalcali, Adem; Ozturk, Turgut; Ocak, CemilIntensive studies are conducted on electric vehicles (EV) in recent years as alternative to fossil fuels. But range and battery problems prevent to take-off EV on the market. By designing of urban use EV can be eliminated mentioned disadvantages. But Urban traffic style has some difficulties for electrical motors (EM) such as unsteady velocity changes and stop-go along the traffic. So, starting Torque of EM becomes importer beside of weight and efficiency for urban use EVs. In this study, we proposed an induction motor (IM) with squirrel cage by optimizing rotor slot structure for higher starting torque and efficiency. The physical parameters of the rotor were defined as variables by parametric approximation method. Totally, 19008 of analyzes were performed at each point within the specified limits. Changes of the efficiency, weight, nominal and starting torque were obtained to determine optimized induction motor.Öğe InP/InGaAs Uni-Traveling-Carrier Photodiode (UTC-PD) With Improved EM Field Response(Ieee-Inst Electrical Electronics Engineers Inc, 2022) Jabeen, Maria; Haxha, Shyqyri; Flint, Ian; Ozturk, Turgut; Charlton, Martin D. B.; AbdelMalek, FathiIn this article, a unique structure of InP/InGaAs uni-traveling-carrier photodiode (UTC-PD) is proposed. Compared with the one-sided junction photodiode, the UTC-PD has the advantages of a simpler epitaxial layer structure while maintaining the characteristics of high bandwidth and high output power loss profile. Simulated results show that a large built-in electric field can be generated under illumination, which aids UTC carrier velocity. The merits of the new structure are compared to a standard UTC-PD photodiode in terms of improved electric field and carrier concentration response. It is demonstrated that the photogeneration and light absorption of UTC-PDs are improved by incorporating a step-like internal texture of cones and dots profile in the photo absorption layer. The simulated device shows a peak electrical 3-dB bandwidth of 65 GHz at a low light intensity and reverse bias voltage. The performance characteristics of 1-D and 2-D UTC-PD simulations, including internal electric field distribution, energy band diagram, carrier concentration, and power loss distribution, are carefully studied. A theoretical discussion of the working principle and key performance characteristics of a UTC-PD enhanced by heterojunction design is reported. The entire physical environment is modeled and simulated through the finite element method (FEM) using commercial software. The proposed photodiode structure configuration is designed and optimized for photodetectors for high RF frequencies at different light intensities. To the best of our knowledge, the obtained bandwidth and electric field response is the fastest among those reported for other various higher wavelength photodiodes.Öğe An Investigation of the Effect of Embedded Gold Nanoparticles in Different Geometric Shapes on the Directivity of THz Photoconductive Antennas(Eos Assoc, 2023) Karasu, Yunus Emre; Uluer, Ihsan; Ozturk, TurgutThis study aims to show how Terahertz (THz) Photoconductive Antennas (PCAs) affect the radiation directivity when gold nanoparticles of various geometric shapes are embedded in the gap region between the electrodes of THz PCAs. Three different PCAs, in the frequency range of 0.1 to 2 THz, conventional and after the addition of cylindrical, triangular, square, and hexagonal geometric gold nanoparticles to the antenna gap region between the electrodes, were built and simulated. The antenna directivity increased from 4.71 dBi to 4.92 dBi when square nanoparticles were added to the bowtie PCA, from 4.33 dBi to 4.45 dBi when triangular nanoparticles were added to the dipole PCA, and from 7.18 dBi to 7.52 dBi when square nanoparticles were added to the Vivaldi PCA.Öğe Materials classification by partial least squares using S-parameters(Springer, 2016) Ozturk, Turgut; Uluer, Ihsan; Unal, IlhamiThis paper presents a simple and usable algorithm, which is called Partial Least Squares, to classify the samples in different thicknesses and frequency range. This model employed to reconstruct the samples using S-parameters which are collected by Vector Network Analyzer in Free Space Measurement method. The relationship of between S-parameters is showed to classify the materials using proposed model. The Partial Least Squares algorithm has a good potential to classify the different samples with non-contactless and non-destructive measurement method. The classification process will be easy by using the proposed model, due to its practical and simple usage. In addition, the extraction techniques, which are Nicolson Ross Weir, Newton-Raphson, and Genetic Algorithm, are used in order to extract the dielectric constant of samples, in this study. The Newton-Raphson algorithm is selected to obtain the complex permittivity of samples since it gives best results than other extracting techniques and the results are used for classification.Öğe Materials classification by partial least squares using S-parameters (vol 27, pg 12701, 2016)(Springer, 2019) Ozturk, Turgut; Uluer, Ihsan; Unal, IlhamiThe original version of this article unfortunately published incorrectly in the definition of complex permittivity extraction given in the relation (5) of [1] due to its minus sign.Öğe Permittivity Measurements for Dielectric Lens and Dielectric Rod Antenna Designs(Ieee, 2016) Panin, Sergey B.; Unal, Ilhami; Sayinti, Aysun; Ozturk, Turgut; Tekbas, MustafaFor dielectric materials being often utilized in quasi-optical components, the permittivity was evaluated by free-space method in W-band. The obtained permittivity value was applied to designing of low aberration large aperture aspheric dielectric lens and dielectric waveguide rod antenna. These components composed the antenna system for the passive radiometric imaging in 90-100 GHz frequency range. This antenna system was experimentally demonstrated to successfully detect and recognize the metallic weapon hidden under outer clothing.Öğe Reduction of S-parameter errors using singular spectrum analysis(Amer Inst Physics, 2016) Ozturk, Turgut; Uluer, Ihsan; Unal, IlhamiA free space measurement method, which consists of two horn antennas, a network analyzer, two frequency extenders, and a sample holder, is used to measure transmission (S-21) coefficients in 75-110 GHz (W-Band) frequency range. Singular spectrum analysis method is presented to eliminate the error and noise of raw S-21 data after calibration and measurement processes. The proposed model can be applied easily to remove the repeated calibration process for each sample measurement. Hence, smooth, reliable, and accurate data are obtained to determine the dielectric properties of materials. In addition, the dielectric constant of materials (paper, polyvinylchloride-PVC, Ultralam (R) 3850HT, and glass) is calculated by thin sheet approximation and Newton-Raphson extracting techniques using a filtered S-21 transmission parameter. Published by AIP Publishing.Öğe A Review of Millimeter Wave Communication for 5G(Ieee, 2018) Seker, Cihat; Guneser, Muhammet Tahir; Ozturk, TurgutThe millimeter wave (mmWave) bands give new facilities with tremendous amount of spectrum to fifth generation (5G) mobile communication network to supply mobile data demand, which is expanding out of control. Essential differences are considered between conventional systems and mmWave communications, regarding directivity, sensitivity to blockage and high propagation loss. mmWave brings various challenges in communication on some issues such as anti-blocking, interference management, spatial reuse, dynamic control and system design for fully utilizing. In this study, we surveyed on solutions and standards for these challenges and we proposed design principles in architecture and protocols for mmWave communications. And previous studies in the literature on whether the millimeter wave band can be tested in small cell access in 5G, cellular access in 5G and wireless backhaul in 5G or not have been investigated. Also, we described prospective using areas of mmWave in 5G.
