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Öğe Asymmetric transmission of linearly polarized electromagnetic waves using chiral metamaterials with constant chirality over a certain frequency band(World Scientific Publ Co Pte Ltd, 2014) Dincer, Furkan; Karaaslan, Muharrem; Akgol, Oguzhan; Unal, Emin; Sabah, CumaliIn this study, a dynamic chiral metamaterial (MTM) structure leading to an asymmetric electromagnetic (EM) wave transmission for linear polarization is presented. The structure is composed of square-shaped resonator with gaps on both sides of a dielectric substrate with a certain degree of rotation. The dynamic structure is adjustable via various parameters to fit any desired frequency ranges. Theoretical and experimental analysis of the proposed structure are conducted and given in detail. The suggested model can provide constant chirality over a certain frequency band and thus, it can be used to design myriad novel devices such as EM transmission and antireflection filters, and polarization rotators for desired frequencyÖğe Asymmetric transmission of linearly polarized light through dynamic chiral metamaterials in a frequency regime of gigahertz-terahertz(Spie-Soc Photo-Optical Instrumentation Engineers, 2014) Ozer, Zafer; Dincer, Furkan; Karaaslan, Muharrem; Akgol, OguzhanIn a lossy media, anisotropic chiral metamaterial (MTM) structures with normal incidence asymmetric transmission of linearly polarized electromagnetic (EM) waves are investigated and analyzed in both microwave and terahertz frequency regimes. The proposed lossy structures are used to perform dynamic polarization rotation and consist of square-shaped resonators with gaps on both sides of dielectric substrates with a certain degree of rotation. Asymmetric transmission of a linearly polarized EM wave through the chiral MTMs is realized by experimental and numerical studies. The dynamic structures are adjustable via various parameters to be tuned for any desired frequency regimes. From the obtained results, the suggested structure can be used to design new polarization control devices for desired frequency regimes. (c) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.Öğe Biosensor applications of chiral metamaterials for marrowbone temperature sensing(Taylor & Francis Ltd, 2015) Sabah, Cumali; Dincer, Furkan; Karaaslan, Muharrem; Bakir, Mehmet; Unal, Emin; Akgol, OguzhanIn this paper, we have designed, simulated, and analyzed a microwave biosensor based on chiral metamaterials (MTMs) to detect pig biological tissues which are widely used as a trial for medical explorations and researches. There are various types of biosensor structures based on MTMs in the literature. However, only a limited number of study is conducted on biosensors based on chiral MTMs; therefore, our study is one of the pioneer works for this type of research. The proposed diamond-shaped resonator-based structures are numerically investigated and analyzed in detail in the microwave frequency regime. The results are in good agreement which lead us to conclude that our structure can be easily used as an effective instrument for biosensing applications in medical technologies.Öğe Chiral metamaterial structures with strong optical activity and their applications(Spie-Soc Photo-Optical Instrumentation Engineers, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, CumaliWe numerically and experimentally introduce a chiral metamaterial (MTM) showing strong optical activity, dynamical circular dichroism, and mechanical tunability because of its efficient design. The proposed chiral MTM structure is composed of bi-layered discontinuous cross-wire-strips, and utilized in order to realize polarization rotation. It provides a giant negative refractive index and a large chirality. We also present a detailed numerical analysis in order to explain the physical interpretation of the designed structure mechanism with a parametric study. Moreover, an MTM absorber application of the proposed chiral MTM is presented to show an additional feature of the model. The introduced chiral design offers a much simpler geometry and more efficient results. In addition, the structure provides chiral nihility unlike the other chiral MTM studies in the literature. The experimental results of the fabricated prototype are in good agreement with the numerical simulations. As a result, the suggested chiral MTM enables myriad potential applications in polarization converters, radar, and military technologies. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)Öğe Design of Polarization- and Incident Angle-Independent Perfect Metamaterial Absorber with Interference Theory(Springer, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, CumaliA perfect metamaterial absorber is realized and its properties are theoretically, numerically and experimentally investigated at microwave frequencies. In addition, polarization and incident angle independencies are also tested for the structure. Theoretical, numerical and experimental results show that the proposed model has many advantages compared to those in the literature, such as perfect absorption, polarization and incident angle independencies, very simple design, and operation over a sufficiently wide band. A simple configuration is chosen for the proposed model so that it can be easily tuned for other frequency regimes to realize new absorbers for applications such as sensors and stealth technology.Öğe Design of two axes sun tracking controller with analytically solar radiation calculations(Pergamon-Elsevier Science Ltd, 2015) Yilmaz, Saban; Ozcalik, Hasan Riza; Dogmus, Osman; Dincer, Furkan; Akgol, Oguzhan; Karaaslan, MuharremPhotovoltaic systems have gained a great deal of interest in the world and these studies performed on this subject have been gaining more and more importance. In order to design new PV systems that will be installed to operate in more efficient and more feasible way, it is necessary to analyze parameters like solar radiation values, the angle of incidence of the genus, temperature etc. Therefore, in this study, theoretical works have been performed for solar radiation and angle of incidence values of any location, plus an experimental study was carried out on a system tracking the sun in two axes and in a fixed system. The performed prototype is also adapted into a PV system with 4.6 kW power. Theoretical data are consistent with the data obtained from the PV system with 4.6 kW power. This study will be an important guide for the future PV power stations. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Electromagnetic energy harvesting and density sensor application based on perfect metamaterial absorber(World Scientific Publ Co Pte Ltd, 2016) Bakir, Mehmet; Karaaslan, Muharrem; Dincer, Furkan; Akgol, Oguzhan; Sabah, CumaliThe proposed study presents an electromagnetic (EM) energy harvesting and density sensor application based on a perfect metamaterial absorber (MA) in microwave frequency regime. In order to verify the absorption behavior of the structure, its absorption behavior is experimentally tested along with the energy harvesting and sensing abilities. The absorption value is experimentally found 0.9 at the resonance frequency of 4.75 GHz. In order to harvest the EM energy, chips resistors are used. In addition, the suggested model is analyzed for its dependency on polarization angles. The results show that the perfect MA can be easily and efficiently used for EM energy harvesting applications. Moreover, as an additional feature of the model, we also realized a density sensor application. It can be seen that this structure can be used as a multi-functional device and configured for many other sensing applications.Öğe Electromagnetic Energy Harvesting By Using Tunable Metamaterial Absorbers(Ieee, 2015) Bakir, Mehmet; Karaaslan, Muharrem; Dincer, Furkan; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, CumaliIn this study, electromagnetic (EM) energy harvesting by using metamaterial absorber is numerically explained. Operation frequency is 2.40 GHz since it is the industrical scientific and medical (ISM) band. This band is especially chosen due to most of the customer electronic devices are working in this band. Split ring resonator that have two splits on it used in this study, chip resistors are placed on these splits for wireless energy transfer to the devices. 83.6% efficient electromagnetic energy harvesting is theoretically realized.Öğe Flexible chiral metamaterials with dynamically optical activity and high negative refractive index(World Scientific Publ Co Pte Ltd, 2015) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, CumaliWe demonstrate numerically and experimentally chiral metamaterials (MTMs) based on gammadion-bilayer cross-wires that uniaxially create giant optical activity and tunable circular dichroism as a result of the dynamic design. In addition, the suggested structure gives high negative refractive index due to the large chirality in order to obtain an efficient polarization converter. We also present a numerical analysis in order to show the additional features of the proposed chiral MTM in detail. Therefore, a MTM sensor application of the proposed chiral MTM is introduced and discussed. The presented chiral designs offer a much simpler geometry and more efficient outlines. The experimental results are in a good agreement with the numerical simulation. It can be seen from the results that, the suggested chiral MTM can be used as a polarization converter, sensor, etc. for several frequency regimes.Öğe Increasing Bandwidth in Antenna Applications By Using Chiral Metamaterials(Ieee, 2015) Dincer, Furkan; Karaaslan, Muharrem; Bakir, Mehmet; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, CumaliChiral metamaterials are such materials that cannot be found in the nature and show exotic properties as negative refraction index. One of the most important properties of chiral metamaterials is to show optical activity by changing the polarization of the electromagnetic wave. In this way, an electromagnetic wave can be directed and can be controlled. Furthermore, cross coupling is created between electric field and magnetic field in the chiral medium In this study, focusing gain and effects on the antenna applications are searched. Since chiral metamaterials have exotic properties, they have advantages in antennas, gain, bandwidth and designing small material dimensions. 1 GHz bandwidth is obtained in this study.Öğe Multifunctional metamaterial sensor applications based on chiral nihility(Springer, 2017) Bakir, Mehmet; Karaaslan, Muharrem; Akgol, Oguzhan; Sabah, CumaliIn this paper, chiral nihility based pressure, density, temperature and moisture content metamaterial sensor applications are investigated in detail. A chiral nihility'' medium in which both the permittivity and the permeability tend to zero is investigated. Gammadion shaped resonators particularly designed for chiral nihility are introduced. Bandwidths and signal strengths show admissible results. Simulation and experimental results prove that chiral nihility occurred at the resonance frequencies when medium parameters are retrieved. The pressure and density sensor applications of the proposed sensor study are realized both numerically and experimentally, and the obtained results show good agreements with each other.Öğe New generation planar chiral metamaterials with small and constant chirality over a certain frequency band(World Scientific Publ Co Pte Ltd, 2015) Dincer, Furkan; Karaaslan, Muharrrem; Akgol, Oguzhan; Unal, Emin; Demirel, Ekrem; Sabah, CumaliChiral metamaterial (MTM) researchers generally concentrate and aim to obtain large chirality with optical activity in certain frequencies. However, new generation planar chiral MTM which have small and constant/flat chirality over a certain frequency band have not queried by this time in literature. In fact, this area is mostly ignored by researchers. This study, first one according to best of our knowledge in the literature, is investigating the small and constant/fixed chirality and focuses on the new generation planar chiral MTM based on circular split ring resonators (SRRs), in details. It can be seen from the results that the proposed model can provide small and constant/flat chirality over a certain frequency band and thus it can be used to design myriad novel devices such as polarization rotators, and electromagnetic transmission and antireflection filters for several frequency regions.Öğe Perfect metamaterial absorber with polarization and incident angle independencies based on ring and cross-wire resonators for shielding and a sensor application(Elsevier Science Bv, 2014) Sabah, Cumali; Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Demirel, EkremWe report the design, characterization and experimental verification of a perfect metamaterial absorber (MA) based on rings and cross wires (RCWs) configurations that operate in the microwave regime. The suggested [VIA provides perfect absorption with incident angle and polarization independencies which can be used for various shielding applications. Maximum absorption rate is 99.9% at 2.76 GHz for simulation and 99.4% at 2.82 GHz for experiment, respectively. The experimental results of the fabricated prototype are in good agreement with the numerical simulations. We also present a numerical analysis in order to explain physical interpretation of MA mechanism in detail. Moreover, a sensor application of the proposed MA is introduced to show additional feature of the model. As a result, proposed MA enables myriad potential applications in S band radar and medical technologies. (c) 2014 Elsevier By. All rights reserved,Öğe Polarization and angle independent perfect metamaterial absorber based on discontinuous cross-wire-strips(Taylor & Francis Ltd, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Demirel, Ekrem; Sabah, CumaliThis study presents design, fabrication, and measurement of a metamaterial absorber (MA) based on discontinuous cross-wire-strip (CWS) resonators. This suggested that MA has a simple geometry configuration and introduces perfect absorption approximately 99.79% at 3.42 GHz for simulation and 99.72% at 3.44 GHz for experiment. In addition, the designed model can be used to realize the broadband absorber for desired frequency ranges. Besides, numerical simulations validate that the MA could achieve very high absorptions at wide angles of incidence for both transverse electric and transverse magnetic waves. The experimental results are in good agreement with the numerical simulations. Moreover, this study presents a numerical analysis in order to explain physical interpretation of MA mechanisms in detail. The proposed model and its variations enable myriad potential applications such as stealth and radar technologies.Öğe Polarization Angle Independent Perfect Metamaterial Absorbers for Solar Cell Applications in the Microwave, Infrared, and Visible Regime(Emw Publishing, 2014) Dincer, Furkan; Akgol, Oguzhan; Karaaslan, Muharrem; Unal, Emin; Sabah, CumaliWe design, characterize, and analyze a new kind of metamaterial (MTM) absorber (MA) in different frequency regions for the solar cell applications. This MTM based structure is particularly presented in a range of the solar spectrum in order to utilize the solar energy effectively. The proposed MTM based solar cell provides perfect absorption for both infrared and visible frequency ranges and can be used for the realization of more efficient new solar cells. The structure is also tested in terms of the polarization angle independency. The suggested MA has a simple configuration which introduces flexibility to adjust its MTM properties to be used in solar cells and can easily be re-scaled for other frequency ranges. Our experimental results in microwave frequencies confirm the perfect absorption for the resonance frequency and agree with the simulation results. This means that the developed MA for solar cells will offer perfect absorption in infrared and even in visible frequencies.Öğe Polarization-insensitive FSS-based perfect metamaterial absorbers for GHz and THz frequencies(Amer Geophysical Union, 2014) Sabah, Cumali; Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, OguzhanNew perfect frequency selective surface (FSS) metamaterial absorbers (MAs) based on resonator with dielectric configuration are numerically presented and investigated for both microwave and terahertz frequency ranges. Also, to verify the behaviors of the FSS MAs, one of the MAs is experimentally analyzed and tested in the microwave frequency range. Suggested FSS MAs have simple configuration which introduces flexibility to adjust their FSS metamaterial properties and to rescale the structure easily for any desired frequency range. There is no study which simultaneously includes microwave and terahertz absorbers in a single design in the literature. Besides, numerical simulations verify that the FSS MAs could achieve very high absorption levels at wide angles of incidence for both transverse electric and transverse magnetic waves. The proposed FSS MAs and their variations enable many potential application areas in radar systems, communication, stealth technologies, and so on.
