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The analysis on sun tracking and cooling systems for photovoltaic panels
(Pergamon-Elsevier Science Ltd, 2013) Rustemli, Sabir; Dincer, Furkan; Unal, Emin; Karaaslan, Muharrem; Sabah, Cumali
This paper presents a review study on the effects of sun tracking and cooling systems. So far, many studies (and case studies too) have been analyzed and evaluated in the literature. Existing studies show that sun tracking system is significantly affecting energy generation capacity of photovoltaic panel. Other effecting parameter is the cooling system which has small effect on PV panel power generation but this totally depends on the location of installation system. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.
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, Cumali
In 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 frequency
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, Utku
The 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.
Biosensor applications of chiral metamaterials for marrowbone temperature sensing
(Taylor & Francis Ltd, 2015) Sabah, Cumali; Dincer, Furkan; Karaaslan, Muharrem; Bakir, Mehmet; Unal, Emin; Akgol, Oguzhan
In 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.
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, Cumali
We 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)
Chiral Metamaterials with Strong and Dynamically Optical Activity
(Ieee, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Sabah, Cumali; Delihacioglu, Kemal
In 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.
Design and analysis of perfect metamaterial absorber in GHz and THz frequencies
(Taylor & Francis Ltd, 2015) Dincer, Furkan; Karaaslan, Muharrem; Sabah, Cumali
The new perfect metamaterial absorber (MA) based on square resonator with gap configuration is numerically (for GHz and THz frequency regime) and experimentally (for GHz frequency regime) presented and investigated. The proposed MA has a simple configuration which introduces flexibility to adjust its metamaterial properties and easily rescale the structure for other frequency regimes. In addition, polarization and incident angle independencies of the proposed model are analyzed for the THz frequency regime. The suggested structure could achieve very high absorption at wide angles of polarization and incident angles for both transverse electric and transverse magnetic waves. At resonance frequencies, absorption results are realized around 99.99% at 5.48GHz and 99.92% at 0.865THz for their respective frequency regimes. Besides numerical results in GHz and THz frequencies, experimental results are also obtained for GHz frequency regime. The proposed MA and its variations enable myriad potential applications in areas such as defense systems, communication, stealth technologies, and so on.
Design of Polarization and Incident Angle Insensitive Dual-Band Metamaterial Absorber Based on Isotropic Resonator
(Emw Publishing, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
Polarization and incident angle independent metamaterial-based absorber (MA) which acts as a strong dual-band resonator is designed and constructed. Besides, a method to design single/dualband MA is presented in detail. The proposed model is based on isotropic ring resonator with gaps and octa-star strip (OSS) which allows maximization in the absorption because of the characteristic features of the structure. Reflection and absorption responses are obtained both numerically and experimentally and compared to each other. Two maxima in the absorption are experimentally obtained around 90% at 4.42 GHz for the first band and 99.7% at 5.62 GHz for the second band which are in good agreement with the numerical simulations (95.6% and 99.9%, respectively). The numerical studies verify that the dual-band MA can provide perfect absorption at wide angles of incidence for both transverse electric (T E) and transverse magnetic (TM) waves. The proposed model can easily be used in many potential application areas such as security systems, sensors, medical imaging technology.
Design of Polarization- and Incident Angle-Independent Perfect Metamaterial Absorber with Interference Theory
(Springer, 2014) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, Cumali
A 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.
Design of tunable and dual/multi-band metamaterial based perfect microwave absorber
(Ios Press, 2015) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Sabah, Cumali
Tunable and multi-band metamaterial (MTM) based perfect microwave absorber (MA) is designed, implemented, and characterized. Firstly, dual-band MA with has two distinct resonances is investigated both numerically and experimentally which is also tested according the incident angle and polarization independencies. Then, the modified versions of MA are investigated and compared with respect to their absorbance, mechanical tunability, and multi-band characters. As a result, the suggested MAs with perfect absorption (including incident angle and polarization independencies) display good performance among their counterparts and can be used in myriad potential applications such as high frequency and sensor applications which are also presented.
DUAL-BAND POLARIZATION INDEPENDENT METAMATERIAL ABSORBER BASED ON OMEGA RESOANATOR AND OCTA-STARSTRIP CONFIGURATION
(Emw Publishing, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Sabah, Cumali
Dual-band metamaterial absorber (MA) with polarization independency based on omega (Omega) resonator with gap and octastar strip (OSS) configuration is presented both numerically and experimentally. The suggested MA has a simple configuration which introduces flexibility to adjust its metamaterial (MTM) properties and easily re-scale the structure for other frequencies. In addition, the dualband character of the absorber provides additional degree of freedom to control the absorption band(s). Two maxima in the absorption are experimentally obtained around 99% at 4.0 GHz for the first band and 79% at 5.6 GHz for the second band which are in good agreement with the numerical simulations (99% and 84%, respectively). Besides, numerical simulations validate that the MA could achieve very high absorption at wide angles of incidence for both transverse electric (TE) and transverse magnetic (TM) waves. The proposed MA and its variations enable myriad potential applications in medical technologies, sensors, modulators, wireless communication, and so on.
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, Cumali
The 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.
Electromagnetic Energy Harvesting By Using Tunable Metamaterial Absorbers
(Ieee, 2015) Bakir, Mehmet; Karaaslan, Muharrem; Dincer, Furkan; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
In 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.
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, Cumali
We 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.
Giant Circular Dichroism in Chiral Metamaterials
(Ieee, 2013) Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Bakir, Mehmet; Erdiven, Utku; Sabah, Cumali
We 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.
Increasing Bandwidth in Antenna Applications By Using Chiral Metamaterials
(Ieee, 2015) Dincer, Furkan; Karaaslan, Muharrem; Bakir, Mehmet; Akgol, Oguzhan; Unal, Emin; Delihacioglu, Kemal; Sabah, Cumali
Chiral 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.
Multifunctional metamaterial sensor applications based on chiral nihility
(Springer, 2017) Bakir, Mehmet; Karaaslan, Muharrem; Akgol, Oguzhan; Sabah, Cumali
In 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.
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, Cumali
Chiral 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.
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, Ekrem
We 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,
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, Cumali
This 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.

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