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We have designed and developed a metamaterial (MTM)-based multipurpose sensor structure capable of sensing moisture, liquid (ethyl alcohol-ethanol-in our case) density in pure water and the concrete aging. The structure is composed of a rectangular shape MTM cell resonator which can be adjusted to any desired frequency range depending on the application area and the material to be sensed. The material is put into a plastic rectangular pipe placed in a hole located in the middle of the structure. Depending on the response of the proposed model to the electromagnetic properties of the material under test (MUT), overall resonance frequency shifts providing the information to accurately estimate the soil moisture, concrete age and density rate of the sensed liquid samples in real time. The resonance frequency has been carefully chosen so that the MUT has a linear variation in its electromagnetic response behaviors. It is aimed for future studies to adjust the structure for designing a portable multipurpose sensor device and even adjust it to smart phones and sense the materials by simply using smart phones and a small amount of sample in high efficiency. [ABSTRACT FROM AUTHOR]

In this study, we both numerically and experimentally present a metasurface (MS) polarization converter to transform linearly polarized signal into circularly polarized one. The unit cell consists of two rectangular metallic patches placed at the crossed corners of rectangularly arranged inclusions. The results of a full-wave Electromagnetic (EM) simulator are compared to those of free space measurement using two horn antenna at microwave frequency regime. For a linearly polarized antenna, the s-parameters are obtained for both co-polarized and cross-polarized responses. The polarization quality referred to as axial ratio (AR) is expressed by the ratio of these two responses. It is found that, strong polarization conversion activity is obtained with the proposed MS at the frequency of about 3 GHz. As a result, we can generate polarization converter with a wide bandwidth, of interest for microwave filtering, coating, and especially polarization conversion devices. [ABSTRACT FROM AUTHOR]

It is well known that one of the widely used structural materials is ordinary cement mortar. Whereas the mechanical properties are sufficient as structural materials, its shielding effectiveness and prevention properties of microwave signal is insufficient due to the lack of electromagnetically conductive components. Electric Arc Furnace Slag (EAFS) is a by-product which is produced after the melting and the primary acid refining of liquid steel. It has potential to improve both mechanical and electrical properties of cement. In this study, ordinary cement mortar specimens with Electric Arc Furnace Slag are investigated. The EAFS used in this study takes part in the mortar specimens as aggregate. Electrical properties are measured by a vector network analyzer in the frequency range of 3–18 GHz. Both the reflection and transmission of the proposed specimens exposed to EM wave are evaluated by free space measurement techniques at the same frequency range. The compressive strength, flexural tensile strength and shielding effectiveness of mortars are also tested, respectively. The real part of permittivity increases with the increased EAFS content of the mortars up to dielectric constant of 40. Nearly constant and frequency independent characteristics of specimens have potential applications. Furthermore, the effective dielectric constant of permeability of the mortars is explicitly improved in the related frequency ranges with the addition of the EAF slags. The transmission prevention of the EAF slag mortars tend to increase significantly with the increasing ratio of EAF slag content. The minimum transmission is around −70 dB and the transmission below −10 dB for 40% EAF aggregate ratio in mortar which has the best mechanical properties in the entire frequency range and averagely and it is −10 dB lower than that of the cement without EAF aggregates. The shielding effectiveness is in excellent level for 80% and 100% EAFS aggregate levels and that of 40% aggregate ratio is still in a good level with a value varying between 15 dB and 20 dB. Besides, the mortars with 40% EAF slag content exhibit approximately 7 MPa higher compressive strength value and 0.9 MPa higher flexural tensile strength. [ABSTRACT FROM AUTHOR]

A metamaterial (MTM) absorber-based multifunctional sensor is numerically and experimentally realized using meander-line resonators. The proposed sensor device can be used to measure pressure, density, and humidity with perfect signal absorption characteristics at the frequency range of X band. The structure consists of a sensor layer sandwiched between two dielectric slabs. The sensor layer is used to detect unknown environmental parameters with respect to the electromagnetic responses of the material under test. A meanderline type resonator is chosen to achieve highly efficient electrical response at the related frequency range. It is well known that an MTM can be efficiently used for sensing purposes in a microwave regime if the absorption characteristic is approximately linear over the certain frequency band. The proposed model is numerically analyzed for pressure, density, and humidity sensing applications. In addition, the experimental study is carried out to prove the sensing ability of the suggested structure in the case of the density sensing application. The meander-line-based MTM absorber can be used in many application areas, such as the agriculture, medical, and defense industries. [ABSTRACT FROM AUTHOR]

We proposed metamaterial absorber having multi-type split coin resonator based on resistive loads. The numerical simulation results and experimental measurements indicate that broad band absorption with a ratio over 80% can be achieved between 3 and 8 GHz for transverse electromagnetic (TEM) polarization wave at normal incident. Besides, proposed structure is insensitive for incident angle. The electric field and surface current distributions in the absorber are investigated to understand characteristic of absorptivity. In terms of energy harvesting application, proposed structure has 82.21% absorption efficiency and 46.07% harvesting efficiency in totally. The proposed structure can be improved for some practical applications, such as energy harvesting, stealth technology and sensing due to significant features. Furthermore, proposed structure can be used in other frequency regions such as infrared, optical region and terahertz. [ABSTRACT FROM AUTHOR]

There are many studies in literature on chiral metamaterials (MTMs) to obtain large chiralities with dynamic optical activities. With this regard, this new generation planar chiral MTM study focuses on a small, non-dispersive (constant/flat) chirality admittance over an indicated frequency band which has not been investigated so far in literature. This new generation planar chiral MTM provides a small and a constant/fixed chirality which is mostly ignored by the scientists. This study numerically and experimentally investigates and examines these new generation MTMs based on circular split ring resonators (SRRs) with an increased capacitance in details. Obtained results show that the suggested structure can provide a small and constant/flat chirality admittance over a certain frequency band and hence it can be used to design myriad novel electromagnetic (EM) devices such as transmission and antireflection filters, polarization rotators for any desired frequency regions. [ABSTRACT FROM AUTHOR]

In this paper, we have designed, simulated and analyzed a new generation chiral metamaterials (MTMs) with two geometries. There are various types of chiral MTM structures in the literature and almost all of them are indented to be designed for high level of chirality. In fact, small chirality and its application areas were mostly ignored by researchers. In this sense, our study is one of the pioneer works for this type of research. Each structure based on omega resonators (ORs) with small chirality value is investigated both numerically and experimentally. The results are in very good agreement which will lead us to conclude that our structures can be easily used as devices for controlling polarization, EM wave transmission filtering, antireflection and so on for a wide range of the EM spectrum. [ABSTRACT FROM AUTHOR]

This paper presents a system based on artificial neural network (ANN) that predicts ground plane design for desired radiation properties of a monopole antenna with operation band of 4.8 to 5 GHz. The operating frequency can be adapted to any other frequency regimes. Initially, a 180 × 180 mm2 ground plane, which is composed of a copper layer, is designed and integrated to a radiative pole that creates monopole antenna configuration. The ground plane is divided into 18 rows and 18 columns as 18 × 18 matrix so that each unit cell has a square shape having 10 mm side length. Moreover, 152 different ground plane configurations are created by using logic 1 s and 0 s. Multi‐layered feed forward ANN is used along with Scale Conjugate Gradient learning algorithm to design ground plane of the monopole antenna. Simulated 152 random ground plane arrays and obtained radiation patterns are used to train ANN for the ground plane design. If a user wants to manipulate radiation, artificial neural network gives the optimum ground plane design for the desired radiation direction and gain with 91.03% accuracy. Finally, one test antenna is fabricated and experimentally measured to support the results of the simulated one. The proposed ANN model approach can be easily used for antenna applications in the antenna industry. [ABSTRACT FROM AUTHOR]

Highlights • Electromagnetic properties of the concrete with various types of fibers. • Electromagnetic properties of the concrete with various types of orientations. • Electromagnetic properties of the concrete with various types of dispersion. Abstract Including fibers in concretes improves their mechanical properties such as flexural strength, impact load resistance and limited crack propagation. The dispersion, orientation and types of the fibers placed in the concretes affect these mechanical properties. The aim of the study is to propose a standard and a novel prediction method for determining the dispersion and orientation of the concretes in which fibers are reinforced in microwave frequency range. This study demonstrates that determination of both orientation and dispersion of the fibers regardless of the fiber types in concretes is possible by extracting electromagnetic properties of the structures in microwave regime as a nondestructive method. The measurement technique requires sample under test (SUT) and two wideband linearly polarized antennas placed in the front and backside of material under the free space condition. Although there are some studies investigated the fiber content of concrete samples through certain electromagnetic techniques, the proposed novel approach concentrates on the electromagnetic behavior of the fiber reinforced concretes in a very wideband range from 3 GHz to 17 GHz. Unlike the other studies, open space measurement with the help of a vector network analyzer which is capable of measuring up to 43 GHz along with two high gain horn antennas was carried out in the laboratory environment. Time required for exact measurement of dielectric constant and loss factor of the concrete between antennas is less than a minute. A simple and confidential model is carried out to determine both orientation and dispersion of fibers in concrete by observing the changes of dielectric constant and loss factor. The determination of electromagnetic properties of concretes with fibers has potential applications for future nondestructive sensors. In addition, observation of negative dielectric constant and some other electrical properties such as low loss factor and impedance match with free space presented in the study for particular frequency intervals gives a chance for future radome applications in harsh environmental conditions. [ABSTRACT FROM AUTHOR]

Determination of the electrical properties of concretes with different water/cement ratios and investigation of the relationship between their electrical and mechanical properties is a promising technique towards improving novel nondestructive microwave based methods. In this study, this relationship between water-cement ratios/mechanical properties and electrical characteristics of various concretes is investigated in the frequency range of 3-18 GHz. The obtained data provides an accurate measurement results for the researchers to design microwave sensors operating at a constant frequency. Besides, the relationship between the electrical properties and the pressure applied to the concrete is also investigated experimentally for various cement types. The experimental study demonstrates the presumable mechanical characteristic of the concrete by using its dielectric constant values. The dielectric constant is retrieved from the reflection and transmission coefficients (which are more commonly known as scattering parameters) by using Nicolson Ross Weir (NRW) Technique. It is revealed that the most significant frequency point is 18 GHz to determine water/cement ratio and 17 GHz to differentiate applied pressure level by using dielectric constant values of the concrete. [ABSTRACT FROM AUTHOR]

In this paper, we present a wide band metasurface (MS) polarization converter which converts a linearly polarized signal to a right-handed or left-handed circularly polarized signal both numerically and experimentally. The unit cell of MS has three nested rectangular resonators which have two metallic patches at its crossed corners. The simulated and measured results are achieved by a commercial full wave EM simulator and a vector network analyzer with two horn antennas in microwave frequency regime. The S-parameters are obtained for co-polarized and cross-polarized responses and axial ratio is evaluated by the division of these two responses. The axial ratio is kept below 3 dB for efficient polarization converting activity. Correspondingly, axial ratio bandwidth of 800 MHz is obtained. The proposed MS can easily be fabricated and integrated into many desired applications by proper configurations depending on the application area and frequencies. The proposed MS has potential such as polarization converter with 0.75 efficiency in WiMAX frequency band, PMC-like treatment with a phase reflection around 0 and reflection coefficient nearly unity at some frequency points. Beside this, the three nested rectangle MSs also provide opportunities to design low profile antennas with conversion characteristics. [ABSTRACT FROM AUTHOR]

We present numerically and experimentally a dynamic chiral metamaterial (MTM) that creates strong optical activity and circular dichroism. The proposed tunable structure has a very simple and more efficient configuration which introduces flexibility to adjust its EM properties. In addition, it gives a giant negative refractive index due to the high chirality. Our experimental results confirm the strong optical activity for a wide frequency range and agree with the simulation results. Moreover, the proposed chiral MTM provides a wideband and constant/flat chirality over a certain frequency band and thus it can be concluded that the developed chiral MTM based model offers a strong optical activity in terahertz, infrared and even in visible frequencies. [ABSTRACT FROM AUTHOR]

We theoretically and numerically designed a perfect metamaterial absorber at microwave frequencies. The proposed design has a very simple geometry, wide band properties and provides perfect absorption for all polarization angles which is one of the most desired properties for an absorber structure to be used in the applications where the source polarization is unknown. In order to explain the absorption mechanism both numerical and theoretical analyses are carried out. Designed structure offers a perfect absorption at around 9.8 GHz. The resonance frequency does not change depending on the source wave polarization. In addition, it can be easily reconfigured for THz and infrared regimes for different applications such as sensors, defense systems and stealth technologies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 regimes. [ABSTRACT FROM AUTHOR]

In this study, cement additives were replaced with cement in mortar mixtures by mass. Mortar specimens were prepared with different additives and dosages which were mechanically and electromagnetically tested. According to the compressive strength test results, mortars containing ground granulated blast furnace slag had weak early age strength and strong later age compressive strengths values, mortars containing fly ash had lower compressive strength value with increasing amount of additives in the mortar mixture for both 7 and 28-day samples, mortars containing silica fume had the maximum strength values at 20% replacement level and lastly the mortars including more than 10% rice husk ash showed weaker strength behaviors with increasing amount of rice husk ash. Besides, electromagnetic responses of the mortar samples were investigated in the frequency range of 3–18 GHz. The reflection and transmission values were measured and the absorption characteristics were calculated. According to the electromagnetic test results, it is revealed that the mortars including ground granulated blast furnace slag can be utilized in the applications of high stealth technology and electromagnetic shields in a wide frequency range of communication field. An increase in the ratio of fly ash in the mortars reduces the transmission of the electromagnetic wave. Mortars including silica fume had very low values of reflection and transmission. Hence, it is expected that the absorption values must be high due to dependency of absorption to reflection and transmission, and it can be said that mortar with rice husk ash exhibits a strong absorber behavior. [ABSTRACT FROM AUTHOR]

• Mechanic and electromagnetic properties of concrete with boron ores and boron containing wastes are investigated. • Additives improved electromagnetic shielding behavior of the concretes. • Additives does not have affect mechanical properties of the concretes significantly. In this study, mechanical properties electromagnetic (EM), and shielding effectiveness of concrete samples containing boron product and wastes was investigated in details. In order to increase shielding effectiveness of concrete samples from electromagnetic waves, hardened concretes containing boron product and wastes are analyzed according to the Institute of Electrical and Electronics Engineers (IEEE) standards. In addition, the effects of the additives on the strength behaviors of the concretes are also examined to report that besides improving shielding behavior, addition of the minerals would not diminish strength parameters. As a result, the concretes containing boron product and wastes provides 3.16 to 100 times better shielding effectiveness than that of concrete containing only Portland cement which is the control sample. While the additives increase or do not affect negatively compressive strength of the concrete. As a conclusion, additives in concretes enhance shielding effectiveness without affecting the strengths parameters negatively. [ABSTRACT FROM AUTHOR]

Chiral metamaterial-based sensor is designed for sensing the change in substance ratio of chemical substances when combined with distilled water. These samples have been prepared with 10%, 50% and 90% volume fraction of methanol, ethanol, acetone, ammonia and isopropyl alcohol. The complex permittivity of the prepared samples has been measured by Agilent 85070E dielectric probe kit and compared with the simulations. In the proposed design, linear shifts with the frequency bands of more than 100 MHz are observed in different measurements. For different material sensing, pure samples have been used and their reflection coefficient measurement results have been presented. Unique side of this study is that the structure provides very clear and sensitive results and presents a new approach to the microfluidic sensor applications by using the sample holder. [ABSTRACT FROM AUTHOR]

In this study, a novel metamaterial absorber (MA) is designed and numerically demonstrated for solar energy harvesting. The structure is composed of three layers with different thicknesses. The interactions of three layers bring about the plasmonic resonances. Although the main operation frequency of the structure is chosen between 430 and 770 THz, which is the visible light regime, the proposed structure is also investigated in the ultra-violet (UV) region. One can see from the results that the proposed structure carries nearly perfect absorption capacity that is more than 91% at the whole visible light spectrum. The proposed structure even has the absorption capacity of 99% between 556 and 657 THz. In addition, the designed MA is also investigated in terms of its polarization and angle independency. Results show that the proposed structure is independent from the polarization and incident angles. Lastly, the designed structure can be considered to be used in solar energy applications as a harvester since it has an ultra-broadband absorption characteristic in visible light regime. [ABSTRACT FROM AUTHOR]

We propose a microwave imaging structure with GSM, ISM, Wi-Fi, and WiMAX operating frequencies at 1.80, 2.45, and 5.80 GHz, respectively. The suggested structure is based on a microwave antenna-inspired absorber with cavities in resonator layers. Our study, which is validated using simulation and experimental techniques, deals with the absorption of the incident electromagnetic waves at 1.80, 2.45, and 5.80 GHz for creating the image when radio frequency microwave is employed. The above-mentioned three operating frequencies, by which electromagnetic waves are radiated from three different antennas, are read via digital oscilloscope and finally these voltages are converted to 256 gray-leveled pixel values of each cell. During the experimental testing, simulated and tested values complied with each other. Small differences occurred due to calibration and testing errors. The novelty of this study is having image capability with most commonly used frequency bands by absorbing microwave energy. [ABSTRACT FROM AUTHOR]

A new metamaterial absorber (MA) having distinct properties than those given in the literature is investigated. Although several designs have been studied for achieving absorption characteristics in single-band, dual-band and multiple bands within the whole spectrum of solar light, there has been limited number of researches examining the broadband MA in the visible light section of the spectrum. The designed structure is composed of the combination of three layers having different thicknesses including a metallic substrate, dielectric and a metal layer. Due to the sandwich-like structure, it can support the plasmonic resonance. The proposed structure, which provides a maximum absorption level of 99.42% at 579.26 THz, has a high absorption rate of 99% between the frequency band 545 and 628 THz. Numerical results indicate that the proposed structure has perfect absorption which is greater than 90.98% through the whole working frequency band. The dependency of the designed structure on the polarization angle is investigated for different incident angles with TE and TM polarizations as well as the TEM mode. In addition to its potential applications such as solar cells and cloaking, the designed structure can also be considered as a color sensor and an optical frequency sensor. [ABSTRACT FROM AUTHOR]

In this study, a novel octagonal shaped metamaterial based broadband absorber is proposed for energy harvesting at WIMAX wireless communication band. The proposal has an absorption of 99.97 % at 5.5 GHz with a bandwidth of 1 GHz between 5 GHz and 6 GHz in Transverse Electric (TE) mode. Transverse Electric (TE), Transverse Magnetic (TM) and Transverse Electromagnetic (TEM) modes are studied numerically in this paper. In TM and TEM modes, proposed structure has absorption of nearly 96 % and 98 % respectively at 6 GHz. The proposed structure is polarization angle independent which is important for energy harvesting applications. Energy harvesting application is realized by using resistive loads on the design, simulations are parametrically studied on resistive loads and experimental study is realized for reflection coefficient measurement and compared with simulated results. Both experimental and simulated results are complying with each other. The proposed structure has different usage areas in stealth areas, detection and imaging. [ABSTRACT FROM AUTHOR]

A new metamaterial absorber (MA) is investigated and shown numerically for solar energy harvesting for future solar cell applications. The structure consists of two metals and one dielectric layer having different thicknesses. Owing to this combination, the structure exhibits plasmonic resonance characteristics. In the entire spectrum of visible frequency region, the obtained results show that investigated structure has perfect absorptivity which is above 91.8%. Proposed structure also has 99.87% absorption at 613.94 THz and 99% absorption between 548 and 669 THz. The proposed structure also shows both polarization and angle independency for the entire visible region. The MA based solar cell proposes high absorption with an upper ratio of 90% in the widest range of visible spectrum comparing to the studies in literature. Hence, the proposed metamaterial absorber solar cells can be used for invisibility in entire spectrum of visible light. The absorption characteristics of the solar absorber are also investigated for infrared and ultraviolet region. The enhancement of absorption of the structure will provide new type of sensors in these frequency ranges. [ABSTRACT FROM AUTHOR]

We propose the design of a multiband absorber based on multi-layered square split ring (MSSR) structure. The multi-layered metamaterial structure is designed to be used in the frequency bands such as WIMAX, WLAN and satellite communication region. The absorption levels of the proposed structure are higher than 90% for all resonance frequencies. In addition, the incident angle and polarization dependence of the multi-layered metamaterial absorber and harvester is also investigated and it is observed that the structure has polarization angle independent frequency response with good absorption characteristics in the entire working frequency band. The energy harvesting ratios of the structure is investigated especially for the resonance frequencies at which the maximum absorption occurs. The energy harvesting potential of the proposed MSSRs is as good as those of the structures given in the literature. Therefore, the suggested design having good absorption, polarization and angle independent characteristics with a wide bandwidth is a potential candidate for future energy harvesting applications in commonly used wireless communication bands, namely WIMAX, WLAN and satellite communication bands. [ABSTRACT FROM AUTHOR]

A novel broad-band polarization-independent with wide-angle metamaterial absorber(MA) is investigated and demonstrated for solar energy harvesting applications. The proposed MA is composed of two metal layers which have different thickness and a dielectric layer which is sandwiched between these metal layers. By this combination, the proposed MA indicates plasmonic resonance characteristic. Numeric results show that proposed MA has perfect absorption characteristic which is above 88.28% with wide-angle for all visible region. It shows almost perfect absorption of 98.4% at the resonance frequency of 621.76 THz and has also 90% absorption between frequencies of 445 THz and 770 THz which is nearly all visible light region. Besides, numerical results validate that the proposed 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 for solar cell applications due to have upper ratio of 90% in the widest range of visible spectrum comparing to the studies in literature. In order to show additional features of the proposed structure, parametric studies are realized and discussed. Furthermore, the absorption characteristic of proposed MA is investigated for infrared and ultraviolet region. The enhancement of absorption of the structure will provide new type of sensors in these frequency ranges. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A multi-band perfect metamaterial absorber (MA) based on a cylindrical waveguide with polarization independency is numerically presented and investigated in detail. The proposed absorber has a very simple configuration, and it operates at flexible frequency ranges within the microwave frequency regime by simply tuning the dimensions of the structure. The maximum absorption values are obtained as 99.9%, 97.5%, 85.8%, 68.2% and 40.2% at the frequencies of 1.34 GHz, 2.15 GHz, 3.2 GHz, 4.31 GHz and 5.41 GHz, respectively. The numerical studies verify that the proposed model can provide multi-band perfect absorptions at wide polarization and incident angles due to its rotational symmetry feature. We have also realized sensor and parametric study applications in order to show additional features of the suggested model. The suggested MA enables myriad potential applications in medical technologies, sensors and in defense industry etc. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

Photovoltaic 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

Abstract: 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 MA provides perfect absorption with incident angle and polarization independencies which can be used for various shielding applications. Maximum absorption rate is at for simulation and at 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. [Copyright &y& Elsevier]

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. [ABSTRACT FROM PUBLISHER]

• Sensor design, consisting of a square split-ring resonator and transmission lines. • Achieving the dielectric constants of local spirit-methanol mixtures. • Determining methanol content in the branded local spirit via resonance frequencies. • Having a bandwidth of 150 MHz with the proper sensitivity to detect methanol level. A metamaterial-based transmission line sensor was designed to determine the amount of methanol in methanol-contaminated local spirit samples both numerically and experimentally. The proposed sensor consists of a square split-ring resonator and a transmission line. The dielectric constants of four different types of branded local spirit samples were measured. Electric field distribution has been given when the sample holder was filled with branded local spirit. Then the results were compared to show that they have almost the same characteristics. After different percentages of methanol were added to the chosen branded local spirit samples their dielectric characteristics were observed. Numerical and experimental sensing studies were conducted in these methanol-branded local spirit mixtures. As the methanol content increases in the local spirit samples, the operating frequency shifts linearly. The proposed sensor has 150 MHz bandwith and is capable of determining the level of methanol content in the branded local spirit sample. [ABSTRACT FROM AUTHOR]

• Turkey is the second largest iron and steel producer in Europe. • In order to added value of the mill scale wastes, they were used in the mortars. • The novel mortars had an electromagnetic wave shielder properties. • This may be contributing the solve the scale storage problem of wastes. Electromagnetic (EM) wave shielder mortar can be produced by mixing cement, natural limestone, tap water with mill scale (mill scale-I and mill scale-II) which is one of the biggest disposal area problems of the iron-steel sector in Iskenderun, Hatay. In this paper, the detail analysis and information were presented on the influence of electromagnetic properties of mortars including iron steel industry waste mill scales to contribute the solving waste problems. The mortar samples were prepared using different volume of mill scales (5, 10, 15 and 30%) which were substituted with the natural fine aggregate. The mechanical properties (flexural and compressive strength) and the EM shielding properties (using the free space test method) of the mortars were compared with each other and also a control mortar samples. Our results indicated that the obtained mortars containing 15% mill scale had nearly same mechanical properties with the control mortar and they provided better solution for EM shielding. Especially, the mortar containing mill scale-II might be used to create novel construction material with shielding characteristics in entire wireless communication bands due to the cubic crystal structure and ferromagnetic properties of the mill scale-II. The mortar prepared using mill scale-I might be utilized to fabricate novel high strength radomes that behave as air in transmission respect. All experimental results point out that the waste mill scales are viable candidates for EM wave shielder for the buildings and will gain added value as well as solve the scale storage problem of the iron and steel industry. [ABSTRACT FROM AUTHOR]

• Metamaterial energy harvester based subwavelength-imaging structure. • Energy harvesting by metamaterials. • Image quality enhancement by metamaterials. • Various applications in energy harvesting, wave tracing, crack detection, spy device detection, medical imaging, and so on. Metamaterial energy harvester based subwavelength imaging structure is presented. Besides, 2×2 array patch antenna is designed to create incident radiated signal towards the proposed harvester structure. Harvested energy is converted to DC voltage signal by using Schottky diodes and each cell is represented by 256 grey levelled pixel value. Therefore, any incident electromagnetic wave placed in the operating frequency range can be monitorized. In the experimental study, experiments are realized with and without antenna to investigate the effects of instantaneous electromagnetic waves and the observed images. Afterwards, another experiment is conducted to observe the effects of metal plate which is located between the antenna and the harvester structure. The last experiment is performed by using a Yagi Uda antenna for sub-wavelength imaging. The proposed harvester structure can be used in various applications such as energy harvesting, incident wave tracing, crack detection, spy device detection, medical imaging, and so on. [ABSTRACT FROM AUTHOR]

In this article, a novel wide band polarization and incident angle independent metamaterial absorber (MA) and energy harvesting applications which operates at C (4GHz‐8 GHz) and X (8GHz‐12 GHz) is proposed. The unit‐cell of the proposed structure based on fractal circle loop. Four lumped resistors are mounted the structure to obtain a broad band absorption characteristics. Resistors increase the absorption characteristic of proposed MA significantly at mentioned frequency ranges. In addition, under favor of the resistors proposed MA can convert absorbed energy from incident wave to appearing power. [ABSTRACT FROM AUTHOR]

A new metamaterial absorber structure is designed and characterized both numerically and experimentally for microwave energy harvesting applications. The proposed structure includes four wheel resonators with different dimensions, from which the overall response of the structure can then be obtained by summing all the overlapping frequency responses corresponding to each dimension. The essential operation frequency range of the wheels is selected in such a way that the energy used in wireless communications and found within the environment that we live is absorbed. The dimensions are obtained using parametric study and genetic algorithm to realize wideband absorption response. When the simulation and measurement results are taken into account, it is observed that the metamaterial absorber based harvester has potential to absorb and convert microwave energy with an absorption ratio lying within the range of 80 and 99% for the frequency band of 3-5.9 and 7.3-8 GHz. The conversion efficiency of the structure as a harvester is found to be greater than 0.8 in the interval of 2-5 GHz. Furthermore, the incident angle and polarization dependence of the wheel resonator based metamaterial absorber and harvester is also investigated and it is observed that the structure has both polarization and incident angle independent frequency response with good absorption characteristics in the entire working frequency band. Hence, the suggested design having good absorption, polarization and angle independent characteristics with wide bandwidth is a potential candidate for future energy harvester using wireless communication frequency band. [ABSTRACT FROM AUTHOR]