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Öğe ASYMMETRIC TRANSMISSION OF LINEARLY POLARIZED WAVES AND DYNAMICALLY WAVE ROTATION USING CHIRAL METAMATERIAL(Emw Publishing, 2013) Dincer, Furkan; Sabah, Cumali; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Erdiven, UtkuThe asymmetric transmission of the linearly polarized waves at normal incidence through the lossy anisotropic chiral structure is demonstrated. The proposed chiral metamaterial structure is composed of hi-layered discontinuous cross-wire-strips, and it is utilized in order to realize polarization rotation. Firstly, the theoretical relations between the incident polarization and the polarization rotation are derived using transmission matrices. Secondly, a strong and dynamically asymmetric transmission of linearly polarized electromagnetic wave through the chiral metamaterial has been demonstrated for microwave region, both by simulation and experimentally. The experiment results are in good agreement with the simulation ones. It can be seen from the results that the proposed chiral metamaterial structure can be used to design novel polarization control devices for several frequency regions.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 Based Multifunctional Sensor Applications(Emw Publishing, 2014) Karaaslan, Muharrem; Bakir, MehmetIn this work, sensor abilities of a chiral metamaterial based on split ring resonators with double splits (SRDS) are demonstrated both theoretically and experimentally in X band range. This study is based on transmission measurements and simulations monitoring the resonance frequency changes with respect to the thickness of the sensing layer and permittivity values. Experimental and simulated results show that the resonance frequency of the chiral metamaterial based SRDS sensor is linearly related to the permittivity and the thickness of the sensor layer which creates a suitable approach for sensing environment and organic parameters. When the sensor layer filled with the related material, changes in the tissue temperature, sand humidity and calcium chloride density lead to resonance frequency changes. The physical mechanisms are explained by using both equivalent circuit model and the fundamental sensitivity theorem of chiral sensors. This is the first study investigating a sensing mechanism based on the chiral metamaterials in X band range.Öğe Chiral metamaterial design using optimized pixelated inclusions with genetic algorithm(Spie-Soc Photo-Optical Instrumentation Engineers, 2015) Akturk, Cemal; Karaaslan, Muharrem; Ozdemir, Ersin; Ozkaner, Vedat; Dincer, Furkan; Bakir, Mehmet; Ozer, ZaferChiral metamaterials have been a research area for many researchers due to their polarization rotation properties on electromagnetic waves. However, most of the proposed chiral metamaterials are designed depending on experience or time-consuming inefficient simulations. A method is investigated for designing a chiral metamaterial with a strong and natural chirality admittance by optimizing a grid of metallic pixels through both sides of a dielectric sheet placed perpendicular to the incident wave by using a genetic algorithm (GA) technique based on finite element method solver. The effective medium parameters are obtained by using constitutive equations and S parameters. The proposed methodology is very efficient for designing a chiral metamaterial with the desired effective medium parameters. By using GA-based topology, it is proven that a chiral metamaterial can be designed and manufactured more easily and with a low cost. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)Öğe Chiral Metamaterials with Strong and Dynamically Optical Activity(Ieee, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Sabah, Cumali; Delihacioglu, KemalIn this study, chiral metamaterial that creates strong optical activity and dynamical circular dichroism due to geometry of the structure (gammadion-bilayer cross-wires) is presented. It includes the gammadion with discontinuous bilayer cross wire patterned on opposite sides. The designed chiral metamaterial offers easier fabrication and more efficient result. Also, transmission and reflection coefficients, theta and chirality coefficient of the medium are independently analyzed. It provides strong and dynamical optical activity due to the high chirality. The experimental results match with the results of the numerical study.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 Giant Circular Dichroism in Chiral Metamaterials(Ieee, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Erdiven, Utku; Sabah, CumaliWe demonstrate numerically and experimentally that uniaxial chiral metamaterial creates giant optical activity and circular dichroism due to the large chirality. Also, transmission and reflection coefficients, circular dichroism and chirality values are separately examined and evaluated. The presented chiral designs are combined of the discontinuous bilayer cross-wire patterned on opposite sides. It offers a much simpler geometry and more efficient results. The experimental results are in good agreement with the numerical simulations.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.
